AbuseIPDB scores for clients that committed an offence, within a daily budget (closes #105)

With SWWAF_ABUSEIPDB_KEY set, a client whose history counts an offence
(a broken limit, a ban rule's match or a block rule's refusal, counted
by kind) is checked in the background, at most
SWWAF_ABUSEIPDB_DAILY_BUDGET checks a day, the count kept in
reputation.json. A client, an IPv4 address or an IPv6 /64, is checked by
the address it sent from, and its score serves all its addresses. A
score at or over SWWAF_ABUSEIPDB_MIN_SCORE is a hit for
SWWAF_REPUTATION_ACTION, logged as abuseipdb and alerted with its score.
A failure or the used-up budget gives no score and raises
source_failure. The key goes only in the Key header.

Judgement call: the budget's day is UTC; AbuseIPDB documents no reset time.
Judgement call: each check sent spends budget; a minute's pause after a failure.

Model: opus-5-5

internal/alerts/alerts.go

@@ -1,5 +1,6 @@
-// Package alerts sends alerts on bans, on a source that fails and on a
-// file with an error to each destination set: to the webhook
+// Package alerts sends alerts on bans, on traffic over an anomaly
+// threshold, on a source that fails and on a file with an error to each
+// destination set: to the webhook
 // SWWAF_ALERT_WEBHOOK_URL names, each as one JSON object, as the "Alert
 // webhook schema" section of SPEC.md describes, to the Slack incoming
 // webhook SWWAF_ALERT_SLACK_WEBHOOK_URL names, as a message, and to the
@@ -40,20 +41,27 @@ const (
 	// EventPermanentBan is a permanent ban smallwebwaf made, or a ban it
 	// made permanent.
 	EventPermanentBan = "permanent_ban"
-	// EventWAFBlock, EventAnomaly and EventReputationHit come with the
-	// Core Rule Set, the anomaly thresholds and the reputation sources;
-	// nothing raises them yet.
-	EventWAFBlock      = "waf_block"
-	EventAnomaly       = "anomaly"
+	// EventAnomaly is a count of requests or bytes over an anomaly
+	// threshold.
+	EventAnomaly = "anomaly"
+	// EventWAFBlock comes with the Core Rule Set; nothing raises it yet.
+	EventWAFBlock = "waf_block"
+	// EventReputationHit is a request whose client a blocklist or a DNSBL
+	// zone lists, or whose AbuseIPDB score is a hit.
 	EventReputationHit = "reputation_hit"
-	// EventSourceFailure is GeoJS failing or refusing smallwebwaf.
+	// EventSourceFailure is GeoJS failing or refusing smallwebwaf, a fetch
+	// of a list failing, a query to a DNSBL zone or a check with AbuseIPDB
+	// failing or refused, or the day's AbuseIPDB checks used up.
 	EventSourceFailure = "source_failure"
 	// EventFileError is a rule file or state file edited while smallwebwaf
 	// runs that does not parse, a replacement of the lookup database that
 	// cannot be read, or a state file that cannot be written.
 	EventFileError = "file_error"
-	// EventSummary is the summary of the alerts an hour held back past
-	// SWWAF_ALERT_MAX_PER_HOUR. SWWAF_ALERT_EVENTS does not name it.
+	// EventSummary is the summary sent as an hour ends: of the alerts held
+	// back in it past SWWAF_ALERT_MAX_PER_HOUR, and of the repeats held
+	// back by the cooldowns dropped as it ends, which no alert let through
+	// has given. It is sent with SWWAF_ALERT_MAX_PER_HOUR off too, for
+	// those repeats. SWWAF_ALERT_EVENTS does not name it.
 	EventSummary = "summary"
 )
 
@@ -153,18 +161,22 @@ type Alert struct {
 	ASName   string       `json:"as_name"`
 	Country  string       `json:"country"`
 	// Reason is a short sentence, and Detail what is particular to the
-	// event: for a file_error, its "file", and for a source_failure, its
-	// "source", which the cooldown tells repeats by.
+	// event: for a file_error, its "file", for a source_failure, its
+	// "source", and for an anomaly, its "scope", with the "asn" or the
+	// "name" of some scopes, which the cooldown tells repeats by.
 	Reason string         `json:"reason"`
 	Detail map[string]any `json:"detail"`
 	// SuppressedRepeats is how many repeats of the alert the cooldown
-	// held back since the last one let through.
+	// held back since the last one let through. For a summary, it is how
+	// many the cooldowns dropped as the hour ended had held back that no
+	// alert let through gave.
 	SuppressedRepeats int `json:"suppressed_repeats"`
 }
 
-// Cooldown is, for an event on a netblock, or about a file or a source,
-// when the last alert let through was raised, and how many repeats the
-// cooldown has held back since, as alerts.json holds it.
+// Cooldown is, for an event on a netblock, about a file or a source, or
+// for an anomaly in a scope, when the last alert let through was raised,
+// and how many repeats the cooldown has held back since, as alerts.json
+// holds it.
 //
 //nolint:tagliatelle // the state files use snake_case, as the request log does
 type Cooldown struct {
@@ -172,6 +184,9 @@ type Cooldown struct {
 	Netblock          netip.Prefix `json:"netblock"`
 	File              string       `json:"file,omitempty"`
 	Source            string       `json:"source,omitempty"`
+	Scope             string       `json:"scope,omitempty"`
+	ASN               string       `json:"asn,omitempty"`
+	Name              string       `json:"name,omitempty"`
 	Sent              time.Time    `json:"sent"`
 	SuppressedRepeats int          `json:"suppressed_repeats"`
 }
@@ -214,7 +229,7 @@ type Queue struct {
 
 	mu sync.Mutex
 	// cooldowns are the alerts last let through, by event and netblock,
-	// file or source.
+	// file, source or scope.
 	cooldowns map[cooldownKey]*Cooldown
 	hour      Hour
 
@@ -248,21 +263,28 @@ type destination struct {
 }
 
 // cooldownKey is what makes an alert a repeat of another: the same event
-// on the same netblock, and about the same file or source, as its detail
-// names them. Each is empty for an alert without one.
+// on the same netblock, and about the same file or source, or in the same
+// scope with the same AS number or name, as its detail names them. Each
+// is empty for an alert without one.
 type cooldownKey struct {
 	event    string
 	netblock netip.Prefix
 	file     string
 	source   string
+	scope    string
+	asn      string
+	name     string
 }
 
 // cooldownKeyOf returns what makes another alert a repeat of alert.
 func cooldownKeyOf(alert *Alert) cooldownKey {
 	file, _ := alert.Detail["file"].(string)
 	source, _ := alert.Detail["source"].(string)
+	scope, _ := alert.Detail["scope"].(string)
+	asn, _ := alert.Detail["asn"].(string)
+	name, _ := alert.Detail["name"].(string)
 
-	return cooldownKey{alert.Event, alert.Netblock, file, source}
+	return cooldownKey{alert.Event, alert.Netblock, file, source, scope, asn, name}
 }
 
 // New returns a Queue with no alert yet.
@@ -295,14 +317,14 @@ func New(params Params) *Queue {
 // unless no destination is set or SWWAF_ALERT_EVENTS leaves its event
 // out. It gives alert the instance and the time. An alert that repeats
 // the last one let through less than Cooldown before is held back and
-// counted, and the next one let through gives that count. Past MaxPerHour
-// alerts let through in the hour under way, by the clock, an alert is
-// held back for that hour's summary instead, which is sent once the hour
-// has ended; it starts no cooldown, and the repeats held back before it
-// are given by the next alert let through. Raise never waits: an alert
-// let through joins the queue of each destination, from which Run sends
-// it, and with queueSize alerts waiting for a destination, the oldest is
-// dropped.
+// counted. The next one let through gives that count, unless an hour of
+// the clock ends first after the cooldown has run out: the cooldown is
+// then dropped, and that hour's summary gives the count. Past MaxPerHour
+// alerts let through in the hour under way, an alert is held back for
+// that hour's summary instead, which is sent once the hour has ended; it
+// starts no cooldown. Raise never waits: an alert let through joins the
+// queue of each destination, from which Run sends it, and with queueSize
+// alerts waiting for a destination, the oldest is dropped.
 func (q *Queue) Raise(alert Alert) {
 	if len(q.destinations) == 0 || !slices.Contains(q.params.Events, alert.Event) {
 		return
@@ -425,7 +447,8 @@ func (q *Queue) Suppressed() int64 {
 }
 
 // Snapshot returns the queue's state, as alerts.json holds it, with the
-// cooldowns sorted by netblock, then by event, file and source.
+// cooldowns sorted by netblock, then by event, file, source, scope, AS
+// number and name.
 func (q *Queue) Snapshot() State {
 	q.mu.Lock()
 	defer q.mu.Unlock()
@@ -443,7 +466,9 @@ func (q *Queue) Snapshot() State {
 
 	slices.SortFunc(state.Cooldowns, func(a, b Cooldown) int {
 		return cmp.Or(a.Netblock.Compare(b.Netblock), cmp.Compare(a.Event, b.Event),
-			cmp.Compare(a.File, b.File), cmp.Compare(a.Source, b.Source))
+			cmp.Compare(a.File, b.File), cmp.Compare(a.Source, b.Source),
+			cmp.Compare(a.Scope, b.Scope), cmp.Compare(a.ASN, b.ASN),
+			cmp.Compare(a.Name, b.Name))
 	})
 
 	for _, d := range q.destinations {
@@ -466,7 +491,10 @@ func (q *Queue) Load(state State) {
 
 	for _, cooldown := range state.Cooldowns {
 		cooldown.Netblock = cooldown.Netblock.Masked()
-		key := cooldownKey{cooldown.Event, cooldown.Netblock, cooldown.File, cooldown.Source}
+		key := cooldownKey{
+			cooldown.Event, cooldown.Netblock, cooldown.File, cooldown.Source,
+			cooldown.Scope, cooldown.ASN, cooldown.Name,
+		}
 		q.cooldowns[key] = &cooldown
 	}
 
@@ -538,46 +566,64 @@ func (q *Queue) startCooldown(alert *Alert, now time.Time) {
 
 	q.cooldowns[key] = &Cooldown{
 		Event: alert.Event, Netblock: alert.Netblock, File: key.file, Source: key.source,
-		Sent: now,
+		Scope: key.scope, ASN: key.asn, Name: key.name, Sent: now,
 	}
 }
 
-// endHour ends the hour under way, if now is past it: it queues that
-// hour's summary when alerts were held back in it past MaxPerHour, and
-// forgets the cooldowns that have run out with no repeat held back, which
-// no alert needs any more.
+// endHour ends the hour under way, if now is past it. It drops the
+// cooldowns that have run out, whatever repeats they held back, so that
+// they do not pile up, and queues that hour's summary when alerts were
+// held back in it past MaxPerHour, or when a cooldown dropped had held
+// back repeats, which no alert let through has given: the summary gives
+// them.
 func (q *Queue) endHour(now time.Time) {
 	start := now.Truncate(time.Hour)
 	if !start.After(q.hour.Start) {
 		return
 	}
 
+	repeats := 0
+
+	for key, cooldown := range q.cooldowns {
+		if now.Sub(cooldown.Sent) >= q.params.Cooldown {
+			repeats += cooldown.SuppressedRepeats
+
+			delete(q.cooldowns, key)
+		}
+	}
+
 	heldBack := 0
 	for _, count := range q.hour.HeldBack {
 		heldBack += count
 	}
 
+	var reasons []string
+
 	if heldBack > 0 {
+		reasons = append(reasons, fmt.Sprintf("%d alerts held back in the hour from %s, "+
+			"past the %d an hour SWWAF_ALERT_MAX_PER_HOUR allows", heldBack,
+			q.hour.Start.Format(time.RFC3339), q.params.MaxPerHour))
+	}
+
+	if repeats > 0 {
+		reasons = append(reasons, fmt.Sprintf("%d repeats held back by "+
+			"SWWAF_ALERT_COOLDOWN that no later alert gives", repeats))
+	}
+
+	if len(reasons) > 0 {
 		q.queue(&Alert{
 			Instance: q.params.Instance,
 			Time:     now,
 			Event:    EventSummary,
-			Reason: fmt.Sprintf("%d alerts held back in the hour from %s, past the %d "+
-				"an hour SWWAF_ALERT_MAX_PER_HOUR allows", heldBack,
-				q.hour.Start.Format(time.RFC3339), q.params.MaxPerHour),
+			Reason:   strings.Join(reasons, "; "),
 			Detail: map[string]any{
 				"hour": q.hour.Start, "count": heldBack, "events": q.hour.HeldBack,
 			},
+			SuppressedRepeats: repeats,
 		})
 	}
 
 	q.hour = Hour{Start: start, HeldBack: map[string]int{}}
-
-	for key, cooldown := range q.cooldowns {
-		if now.Sub(cooldown.Sent) >= q.params.Cooldown && cooldown.SuppressedRepeats == 0 {
-			delete(q.cooldowns, key)
-		}
-	}
 }
 
 // queue adds alert to the alerts waiting for each destination.

internal/alerts/alerts_test.go

@@ -381,7 +381,7 @@ func TestAlertsPastTheHourlyLimitAreRolledIntoOneSummary(t *testing.T) {
 	})
 }
 
-func TestRepeatsBeforeAnAlertPastTheHourlyLimitAreGivenByTheNextSent(t *testing.T) {
+func TestRepeatsBeforeAnAlertPastTheHourlyLimitAreGivenByTheSummary(t *testing.T) {
 	t.Parallel()
 
 	synctest.Test(t, func(t *testing.T) {
@@ -401,8 +401,8 @@ func TestRepeatsBeforeAnAlertPastTheHourlyLimitAreGivenByTheNextSent(t *testing.
 		time.Sleep(cooldown)
 		raise()
 
-		// The next hour's first alert gives the two repeats, and the summary
-		// the alert past the limit.
+		// The summary gives the alert past the limit and the two repeats,
+		// and the next hour's first alert none.
 		time.Sleep(time.Hour - cooldown)
 		synctest.Wait()
 		raise()
@@ -413,11 +413,14 @@ func TestRepeatsBeforeAnAlertPastTheHourlyLimitAreGivenByTheNextSent(t *testing.
 		got := webhook.received()
 		if len(got) == 3 {
 			detail, _ := got[1].alert["detail"].(map[string]any)
-			repeats := got[2].alert["suppressed_repeats"]
+			summaryRepeats := got[1].alert["suppressed_repeats"]
+			lastRepeats := got[2].alert["suppressed_repeats"]
 
-			if detail["count"] != float64(1) || repeats != float64(2) {
-				t.Errorf("the summary counts %v alerts, and the last alert gives %v "+
-					"repeats, want 1 and 2", detail["count"], repeats)
+			if detail["count"] != float64(1) || summaryRepeats != float64(2) ||
+				lastRepeats != float64(0) {
+				t.Errorf("the summary counts %v alerts and %v repeats, and the last "+
+					"alert gives %v repeats, want 1, 2 and 0", detail["count"],
+					summaryRepeats, lastRepeats)
 			}
 		}
 
@@ -425,6 +428,70 @@ func TestRepeatsBeforeAnAlertPastTheHourlyLimitAreGivenByTheNextSent(t *testing.
 	})
 }
 
+func TestCooldownsThatHaveRunOutAreDroppedAndTheirRepeatsSummedUp(t *testing.T) {
+	t.Parallel()
+
+	for name, maxPerHour := range map[string]int{"limit off": 0, "limit set": 60} {
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			synctest.Test(t, func(t *testing.T) {
+				params := newParams()
+				params.MaxPerHour = maxPerHour
+				webhook, q := start(t, params)
+
+				// For four hours, a netblock of its own each minute is over an
+				// anomaly threshold twice: an alert, and a repeat the cooldown
+				// holds back.
+				netblocks := 0
+
+				for range 4 {
+					for range 60 {
+						anomaly := alerts.Alert{
+							Event: alerts.EventAnomaly, Netblock: netblock(netblocks),
+							Detail: map[string]any{"scope": "net"},
+						}
+						q.Raise(anomaly)
+						q.Raise(anomaly)
+
+						netblocks++
+
+						time.Sleep(time.Minute)
+					}
+
+					// As the hour ends, only the cooldowns started less than the
+					// cooldown before are kept, in memory and for alerts.json.
+					synctest.Wait()
+
+					kept := len(q.Snapshot().Cooldowns)
+					if kept > int(cooldown/time.Minute) {
+						t.Errorf("after %d netblocks, %d cooldowns are kept, want at most %d",
+							netblocks, kept, int(cooldown/time.Minute))
+					}
+				}
+
+				// An hour on, every cooldown has been dropped, and the summaries
+				// have given every repeat.
+				time.Sleep(time.Hour)
+				synctest.Wait()
+
+				repeats := 0.0
+
+				for _, request := range webhook.received() {
+					count, _ := request.alert["suppressed_repeats"].(float64)
+					repeats += count
+				}
+
+				kept := len(q.Snapshot().Cooldowns)
+				if kept != 0 || repeats != float64(netblocks) {
+					t.Errorf("%d cooldowns are kept and the webhook was given %v repeats, "+
+						"want 0 and %d", kept, repeats, netblocks)
+				}
+			})
+		})
+	}
+}
+
 func TestFailedRequestIsSentAgainWithBackoff(t *testing.T) {
 	t.Parallel()
 
@@ -635,7 +702,8 @@ func TestStateLoadedIntoANewQueueCarriesOn(t *testing.T) {
 		after.Load(roundTrip(t, before.Snapshot()))
 
 		// The new queue sends the alert waiting, holds back the repeat as
-		// the cooldown still runs, and sends the summary of the hour.
+		// the cooldown still runs, and sends the summary of the hour, which
+		// gives both repeats, as the cooldown has run out.
 		after.Raise(alerts.Alert{Event: alerts.EventBan, Netblock: netblock(1)})
 		synctest.Wait()
 		wantEvents(t, webhook, alerts.EventBan)
@@ -644,18 +712,12 @@ func TestStateLoadedIntoANewQueueCarriesOn(t *testing.T) {
 		synctest.Wait()
 		wantEvents(t, webhook, alerts.EventBan, alerts.EventSummary)
 
-		detail, _ := webhook.received()[1].alert["detail"].(map[string]any)
-		if detail["count"] != float64(1) {
-			t.Errorf("the summary counts %v alerts, want 1", detail["count"])
-		}
+		summary := webhook.received()[1].alert
+		detail, _ := summary["detail"].(map[string]any)
 
-		// The cooldown has run out, and the next one gives both repeats.
-		after.Raise(alerts.Alert{Event: alerts.EventBan, Netblock: netblock(1)})
-		synctest.Wait()
-
-		got := webhook.received()
-		if repeats := got[len(got)-1].alert["suppressed_repeats"]; repeats != float64(2) {
-			t.Errorf("the last alert gives %v repeats, want 2", repeats)
+		if detail["count"] != float64(1) || summary["suppressed_repeats"] != float64(2) {
+			t.Errorf("the summary counts %v alerts and %v repeats, want 1 and 2",
+				detail["count"], summary["suppressed_repeats"])
 		}
 	})
 }
@@ -701,8 +763,8 @@ func TestSlackAndNtfyAreSentTheSummaryAndTheRepeatsHeldBack(t *testing.T) {
 		ban := alerts.Alert{Event: alerts.EventBan, Netblock: netblock(1), Reason: "a ban"}
 
 		// The hour's one alert, a repeat of it the cooldown holds back, and
-		// an alert past the limit; once the hour has ended, its summary, and
-		// the next alert, which gives the repeat.
+		// an alert past the limit; once the hour has ended, its summary,
+		// which gives the repeat, and the next alert, which gives none.
 		q.Raise(ban)
 		q.Raise(ban)
 		q.Raise(alerts.Alert{Event: alerts.EventFileError, Reason: "a file error"})
@@ -720,14 +782,14 @@ func TestSlackAndNtfyAreSentTheSummaryAndTheRepeatsHeldBack(t *testing.T) {
 		}
 
 		const summary = "1 alerts held back in the hour from 2000-01-01T00:00:00Z, " +
-			"past the 1 an hour SWWAF_ALERT_MAX_PER_HOUR allows"
+			"past the 1 an hour SWWAF_ALERT_MAX_PER_HOUR allows; 1 repeats held back " +
+			"by SWWAF_ALERT_COOLDOWN that no later alert gives\nsuppressed repeats: 1"
 
 		wantSlackMessage(t, slack[1], "*"+instance+": summary*\n"+summary)
 		wantNtfyMessage(t, ntfy[1], instance+": summary", "default bar_chart", summary)
-		wantSlackMessage(t, slack[2],
-			"*"+instance+": ban*\na ban\nnetblock: 203.0.113.1/32\nsuppressed repeats: 1")
+		wantSlackMessage(t, slack[2], "*"+instance+": ban*\na ban\nnetblock: 203.0.113.1/32")
 		wantNtfyMessage(t, ntfy[2], instance+": ban", "default no_entry",
-			"a ban\nnetblock: 203.0.113.1/32\nsuppressed repeats: 1")
+			"a ban\nnetblock: 203.0.113.1/32")
 	})
 }
 

internal/anomaly/anomaly.go

@@ -0,0 +1,406 @@
+// Package anomaly counts requests and bytes over a minute and an hour, per
+// client, per surrounding netblock, per AS number, for the whole service
+// and per named netblock, and raises an anomaly alert for a count over its
+// threshold, as "Anomaly thresholds" under "Configuration surface" in
+// SPEC.md describes. It refuses and bans nothing. At most 20,000 counters
+// are kept, in memory, and written to alerts.json and read from it by the
+// state package.
+package anomaly
+
+import (
+	"cmp"
+	"fmt"
+	"net/netip"
+	"slices"
+	"sync"
+	"time"
+
+	"github.com/hashicorp/golang-lru/v2/simplelru"
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
+)
+
+// maxCounters is how many counters are kept. Past it, the counter counted
+// least recently is dropped, and starts afresh if it is counted again.
+const maxCounters = 20000
+
+// The scopes, what a counter counts, as the settings, alerts.json and the
+// alerts name them.
+const (
+	// ScopeClient is one client: an IPv4 address, or an IPv6 /64.
+	ScopeClient = "client"
+	// ScopeNet is the netblock around a client, SWWAF_ANOMALY_NET_V4_PREFIX
+	// or SWWAF_ANOMALY_NET_V6_PREFIX long.
+	ScopeNet = "net"
+	// ScopeASN is an AS number.
+	ScopeASN = "asn"
+	// ScopeTotal is the whole service.
+	ScopeTotal = "total"
+	// ScopeWatch is a named netblock of SWWAF_WATCH_NETS.
+	ScopeWatch = "watch"
+)
+
+// Scopes returns every scope.
+func Scopes() []string {
+	return []string{ScopeClient, ScopeNet, ScopeASN, ScopeTotal, ScopeWatch}
+}
+
+// The windows a counter counts in, as the alerts name them.
+const (
+	minute = "minute"
+	hour   = "hour"
+)
+
+// Thresholds are the most requests and the most bytes a scope may have
+// counted in a minute and in an hour before an alert is raised. Zero is
+// off.
+type Thresholds struct {
+	RequestsPerMinute int64
+	RequestsPerHour   int64
+	BytesPerMinute    int64
+	BytesPerHour      int64
+}
+
+// NamedNetblock is a netblock SWWAF_WATCH_NETS names.
+type NamedNetblock struct {
+	Name     string
+	Netblock netip.Prefix
+}
+
+// Params are what New needs.
+type Params struct {
+	// The thresholds of each scope: SWWAF_ANOMALY_CLIENT_*,
+	// SWWAF_ANOMALY_NET_*, SWWAF_ANOMALY_ASN_*, SWWAF_ANOMALY_TOTAL_* and
+	// SWWAF_WATCH_*.
+	Client, Net, ASN, Total, Watch Thresholds
+	// NetV4Prefix and NetV6Prefix are the lengths of the netblock around a
+	// client (SWWAF_ANOMALY_NET_V4_PREFIX and SWWAF_ANOMALY_NET_V6_PREFIX).
+	NetV4Prefix, NetV6Prefix int
+	// NamedNetblocks are SWWAF_WATCH_NETS.
+	NamedNetblocks []NamedNetblock
+	// Alerts receive the anomaly alerts.
+	Alerts *alerts.Queue
+}
+
+// Counter is one scope's counts, as alerts.json holds them: the scope,
+// with the netblock, the AS number or the name that tells it from the
+// others in that scope, and its two buckets of requests and of bytes in
+// the minute and in the hour. A bucket whose threshold is off counts
+// nothing, and is left out.
+//
+//nolint:tagliatelle // the state files use snake_case, as the request log does
+type Counter struct {
+	Scope       string            `json:"scope"`
+	Netblock    netip.Prefix      `json:"netblock,omitzero"`
+	ASN         string            `json:"asn,omitempty"`
+	Name        string            `json:"name,omitempty"`
+	Minute      ratelimit.Buckets `json:"minute,omitzero"`
+	Hour        ratelimit.Buckets `json:"hour,omitzero"`
+	MinuteBytes ratelimit.Buckets `json:"minute_bytes,omitzero"`
+	HourBytes   ratelimit.Buckets `json:"hour_bytes,omitzero"`
+}
+
+// Request is a request that has ended, as the counters count it.
+type Request struct {
+	// Client is the client's address, and ClientGroup the client it is
+	// counted as: its IPv4 address, or its IPv6 /64.
+	Client      netip.Addr
+	ClientGroup netip.Prefix
+	// ASN, ASName and Country are the client's as looked up, each "" when
+	// unknown.
+	ASN, ASName, Country string
+	// Bytes are the request's bytes, as SWWAF_BYTES_COUNT counts them.
+	Bytes int64
+}
+
+// Counters counts each request in the scopes it is in. It is safe for
+// concurrent use.
+type Counters struct {
+	params Params
+
+	mu       sync.Mutex
+	counters *simplelru.LRU[key, *Counter]
+}
+
+// key is what tells a counter from the others: its scope, with its
+// netblock, AS number or name.
+type key struct {
+	scope    string
+	netblock netip.Prefix
+	asn      string
+	name     string
+}
+
+// New returns Counters for params, with nothing counted yet.
+func New(params Params) *Counters {
+	counters, err := simplelru.NewLRU[key, *Counter](maxCounters, nil)
+	if err != nil {
+		panic(err) // NewLRU fails only for a size below one
+	}
+
+	return &Counters{params: params, counters: counters}
+}
+
+// Count counts r, a request that has ended, at now, in each scope it is
+// in whose thresholds are not all off: its client, the netblock around
+// it, its AS number once known, the whole service, and each named
+// netblock it is in. Only the counts whose threshold is set are counted.
+// For each scope whose count is over a threshold, it raises an anomaly
+// alert, for the first such count in the order requests and bytes in the
+// minute, then in the hour; the alert queue's cooldown holds back the
+// repeats. Nothing is refused or banned.
+func (c *Counters) Count(now time.Time, r Request) {
+	var raised []alerts.Alert
+
+	c.mu.Lock()
+
+	for _, scope := range c.scopesOf(r) {
+		counter, found := c.counters.Get(scope.key)
+		if !found {
+			counter = scope.key.counter()
+			c.counters.Add(scope.key, counter)
+		}
+
+		over, passed := counter.add(now, r.Bytes, scope.thresholds)
+		if passed {
+			raised = append(raised, alertFor(r, scope.key, over))
+		}
+	}
+
+	c.mu.Unlock()
+
+	for _, alert := range raised {
+		c.params.Alerts.Raise(alert)
+	}
+}
+
+// Snapshot returns every counter, sorted by scope, then by netblock, AS
+// number and name, as alerts.json lists them.
+func (c *Counters) Snapshot() []Counter {
+	c.mu.Lock()
+
+	counters := make([]Counter, 0, c.counters.Len())
+	for _, counter := range c.counters.Values() {
+		counters = append(counters, *counter)
+	}
+
+	c.mu.Unlock()
+
+	slices.SortFunc(counters, func(a, b Counter) int {
+		return cmp.Or(cmp.Compare(a.Scope, b.Scope), a.Netblock.Compare(b.Netblock),
+			cmp.Compare(a.ASN, b.ASN), cmp.Compare(a.Name, b.Name))
+	})
+
+	return counters
+}
+
+// Load puts counters, read from alerts.json, in place of those held, in
+// the order they were last counted, as the starts of their buckets tell,
+// so that the one counted least recently is dropped first. Each netblock
+// is masked to its length, so that 203.0.113.9/24 is 203.0.113.0/24.
+// Buckets whose time has passed at now are emptied, and a counter left
+// with every bucket empty is dropped.
+func (c *Counters) Load(counters []Counter, now time.Time) {
+	counters = slices.Clone(counters)
+	slices.SortStableFunc(counters, func(a, b Counter) int {
+		return a.lastStart().Compare(b.lastStart())
+	})
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.counters.Purge()
+
+	for _, counter := range counters {
+		counter.Netblock = counter.Netblock.Masked()
+		empty := true
+
+		for _, count := range counter.counts() {
+			if count.buckets.Passed(now, count.length) {
+				*count.buckets = ratelimit.Buckets{}
+			}
+
+			empty = empty && *count.buckets == ratelimit.Buckets{}
+		}
+
+		if !empty {
+			c.counters.Add(counter.key(), &counter)
+		}
+	}
+}
+
+// scope is a scope a request is counted in, and its thresholds.
+type scope struct {
+	key        key
+	thresholds Thresholds
+}
+
+// scopesOf returns the scopes r is in whose thresholds are not all off.
+func (c *Counters) scopesOf(r Request) []scope {
+	p := c.params
+	client := r.Client.Unmap()
+
+	all := []scope{
+		{key{scope: ScopeClient, netblock: r.ClientGroup}, p.Client},
+		{key{scope: ScopeNet, netblock: c.netAround(client)}, p.Net},
+		{key{scope: ScopeTotal}, p.Total},
+	}
+
+	if r.ASN != "" {
+		all = append(all, scope{key{scope: ScopeASN, asn: r.ASN}, p.ASN})
+	}
+
+	for _, named := range p.NamedNetblocks {
+		if named.Netblock.Contains(client) {
+			all = append(all, scope{
+				key{scope: ScopeWatch, netblock: named.Netblock, name: named.Name}, p.Watch,
+			})
+		}
+	}
+
+	return slices.DeleteFunc(all, func(s scope) bool {
+		return s.thresholds == Thresholds{}
+	})
+}
+
+// netAround returns the netblock around client that ScopeNet counts it
+// in: NetV4Prefix or NetV6Prefix long.
+func (c *Counters) netAround(client netip.Addr) netip.Prefix {
+	length := c.params.NetV6Prefix
+	if client.Is4() {
+		length = c.params.NetV4Prefix
+	}
+
+	return netip.PrefixFrom(client, length).Masked()
+}
+
+// overThreshold is a count over its threshold: what it counts, requests or
+// bytes, its window, the count and the threshold.
+type overThreshold struct {
+	kind, window string
+	count        float64
+	threshold    int64
+}
+
+// add counts a request of bytes at now in each of c's counts whose
+// threshold, in thresholds, is set, and returns the first count over its
+// threshold, and whether there is one.
+func (c *Counter) add(
+	now time.Time, bytes int64, thresholds Thresholds,
+) (overThreshold, bool) {
+	// In the order of counts.
+	inOrder := [4]int64{
+		thresholds.RequestsPerMinute, thresholds.BytesPerMinute,
+		thresholds.RequestsPerHour, thresholds.BytesPerHour,
+	}
+
+	var (
+		first  overThreshold
+		passed bool
+	)
+
+	for i, count := range c.counts() {
+		threshold := inOrder[i]
+		if threshold == 0 {
+			continue
+		}
+
+		n := int64(1)
+		if count.kind == ratelimit.KindBytes {
+			n = bytes
+		}
+
+		counted := count.buckets.Add(now, count.length, n)
+		if !passed && counted > float64(threshold) {
+			first = overThreshold{count.kind, count.window, counted, threshold}
+			passed = true
+		}
+	}
+
+	return first, passed
+}
+
+// bucketCount is one of a counter's four counts: requests or bytes, in a
+// window of length, and the buckets they are counted in.
+type bucketCount struct {
+	kind, window string
+	length       time.Duration
+	buckets      *ratelimit.Buckets
+}
+
+// counts returns c's counts: requests and bytes in the minute, then in
+// the hour.
+func (c *Counter) counts() [4]bucketCount {
+	return [4]bucketCount{
+		{ratelimit.KindRequests, minute, time.Minute, &c.Minute},
+		{ratelimit.KindBytes, minute, time.Minute, &c.MinuteBytes},
+		{ratelimit.KindRequests, hour, time.Hour, &c.Hour},
+		{ratelimit.KindBytes, hour, time.Hour, &c.HourBytes},
+	}
+}
+
+// lastStart returns the start of c's latest bucket, which tells, to the
+// minute or to the hour, when c was last counted.
+func (c *Counter) lastStart() time.Time {
+	var latest time.Time
+
+	for _, count := range c.counts() {
+		if count.buckets.Start.After(latest) {
+			latest = count.buckets.Start
+		}
+	}
+
+	return latest
+}
+
+// key returns what tells c from the other counters.
+func (c *Counter) key() key {
+	return key{scope: c.Scope, netblock: c.Netblock, asn: c.ASN, name: c.Name}
+}
+
+// counter returns a counter for k, with nothing counted yet.
+func (k key) counter() *Counter {
+	return &Counter{Scope: k.scope, Netblock: k.netblock, ASN: k.asn, Name: k.name}
+}
+
+// alertFor returns the anomaly alert for o, a count over its threshold in
+// the scope k, which r took over it. It gives r's client, with its AS
+// number, AS name and country, and the netblock counted, of a client, the
+// netblock around it or a named netblock. Its detail gives the scope, the
+// AS number or the name of a scope that has one, the window, what is
+// counted, the count and the threshold.
+func alertFor(r Request, k key, o overThreshold) alerts.Alert {
+	detail := map[string]any{
+		"scope": k.scope, "window": o.window, "kind": o.kind, "count": o.count,
+		"threshold": o.threshold,
+	}
+
+	var counted string
+
+	switch k.scope {
+	case ScopeClient:
+		counted = "the client " + k.netblock.String()
+	case ScopeNet:
+		counted = "the netblock " + k.netblock.String()
+	case ScopeASN:
+		counted = k.asn
+		detail["asn"] = k.asn
+	case ScopeTotal:
+		counted = "the whole service"
+	default: // watch
+		counted = "the named netblock " + k.name + ", " + k.netblock.String()
+		detail["name"] = k.name
+	}
+
+	return alerts.Alert{
+		Event:    alerts.EventAnomaly,
+		Client:   r.Client,
+		Netblock: k.netblock,
+		ASN:      r.ASN,
+		ASName:   r.ASName,
+		Country:  r.Country,
+		Reason: fmt.Sprintf("%s per %s of %s over the threshold of %d", o.kind, o.window,
+			counted, o.threshold),
+		Detail: detail,
+	}
+}

internal/anomaly/anomaly_test.go

@@ -0,0 +1,238 @@
+package anomaly_test
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/netip"
+	"net/url"
+	"reflect"
+	"slices"
+	"testing"
+	"time"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/anomaly"
+	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
+)
+
+// maxCounters is how many counters are kept.
+const maxCounters = 20000
+
+func TestEachScopeHasACooldownOfItsOwn(t *testing.T) {
+	t.Parallel()
+
+	queue := newQueue()
+	office := netip.MustParsePrefix("203.0.113.0/24")
+	overAtTheSecond := anomaly.Thresholds{RequestsPerMinute: 1}
+	counters := anomaly.New(anomaly.Params{
+		Client: overAtTheSecond, Net: overAtTheSecond, ASN: overAtTheSecond,
+		Total: overAtTheSecond, Watch: overAtTheSecond,
+		// The netblock around a client is the client's own, and two names
+		// name one netblock.
+		NetV4Prefix: 32,
+		NamedNetblocks: []anomaly.NamedNetblock{
+			{Name: "office", Netblock: office}, {Name: "hq", Netblock: office},
+		},
+		Alerts: queue,
+	})
+
+	// The first client's second request is over the threshold in the six
+	// scopes it is in. The other client's two are both over it in the whole
+	// service and in each named netblock, three repeats each, and its
+	// second is over it in the scopes of its own, its client, its netblock
+	// and its AS number, which are no repeats.
+	for _, r := range []anomaly.Request{
+		{Client: netip.MustParseAddr("203.0.113.9"), ASN: "AS64496"},
+		{Client: netip.MustParseAddr("203.0.113.10"), ASN: "AS64511"},
+	} {
+		r.ClientGroup = netip.PrefixFrom(r.Client, 32)
+
+		for range 2 {
+			counters.Count(midnight(), r)
+		}
+	}
+
+	waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
+	if len(waiting) != 9 || queue.Suppressed() != 6 {
+		t.Fatalf("%d alerts wait and %d are held back, want 9 and 6: %+v",
+			len(waiting), queue.Suppressed(), waiting)
+	}
+
+	// alerts.json keeps each scope's cooldown: each alert raised again
+	// after a restart is a repeat.
+	data, err := json.Marshal(queue.Snapshot())
+	if err != nil {
+		t.Fatalf("encode: %v", err)
+	}
+
+	var read alerts.State
+
+	err = json.Unmarshal(data, &read)
+	if err != nil {
+		t.Fatalf("decode: %v", err)
+	}
+
+	after := newQueue()
+	after.Load(read)
+
+	for _, alert := range read.Waiting[alerts.DestinationWebhook] {
+		after.Raise(alert)
+	}
+
+	if after.Suppressed() != 9 {
+		t.Errorf("after loading, %d alerts are held back, want 9", after.Suppressed())
+	}
+}
+
+func TestKeepsAtMost20000CountersDroppingTheLeastRecentlyCounted(t *testing.T) {
+	t.Parallel()
+
+	counters := newCounters(anomaly.Params{
+		Client: anomaly.Thresholds{RequestsPerMinute: 1000},
+	})
+
+	for i := range maxCounters {
+		counters.Count(midnight(), request(i))
+	}
+
+	// Counted again, the first client is the most recently counted, and
+	// the second is dropped for a new one.
+	counters.Count(midnight(), request(0))
+	counters.Count(midnight(), request(maxCounters))
+
+	got := counters.Snapshot()
+	if len(got) != maxCounters || !holds(got, 0) || holds(got, 1) ||
+		!holds(got, maxCounters) {
+		t.Errorf("%d counters, holding the first client %v, the second %v and the "+
+			"new one %v, want %d, the first and the new one", len(got), holds(got, 0),
+			holds(got, 1), holds(got, maxCounters), maxCounters)
+	}
+}
+
+func TestLoadEmptiesBucketsWhoseTimeHasPassedAndDropsEmptyCounters(t *testing.T) {
+	t.Parallel()
+
+	counters := newCounters(anomaly.Params{
+		Net:         anomaly.Thresholds{RequestsPerMinute: 1000, RequestsPerHour: 1000},
+		Total:       anomaly.Thresholds{RequestsPerMinute: 1000},
+		NetV4Prefix: 24,
+	})
+	halfAnHourOn := midnight().Add(30 * time.Minute)
+
+	// Half an hour on, the hour's buckets count still, and the minute's
+	// do not.
+	counters.Load([]anomaly.Counter{
+		{
+			Scope:    anomaly.ScopeNet,
+			Netblock: netip.MustParsePrefix("203.0.113.9/24"),
+			Minute:   ratelimit.Buckets{Start: midnight(), Current: 5},
+			Hour:     ratelimit.Buckets{Start: midnight(), Current: 7},
+		},
+		{
+			Scope:  anomaly.ScopeTotal,
+			Minute: ratelimit.Buckets{Start: midnight(), Current: 1},
+		},
+	}, halfAnHourOn)
+
+	// The whole service's counter, left empty, is dropped, and the
+	// netblock read is masked to its length.
+	netblock := anomaly.Counter{
+		Scope:    anomaly.ScopeNet,
+		Netblock: netip.MustParsePrefix("203.0.113.0/24"),
+		Hour:     ratelimit.Buckets{Start: midnight(), Current: 7},
+	}
+	if got, want := counters.Snapshot(), []anomaly.Counter{netblock}; !reflect.DeepEqual(
+		got, want) {
+		t.Errorf("counters read\n%+v\nwant\n%+v", got, want)
+	}
+
+	// A request from the netblock is counted with the requests read.
+	counters.Count(halfAnHourOn, anomaly.Request{
+		Client:      netip.MustParseAddr("203.0.113.9"),
+		ClientGroup: netip.MustParsePrefix("203.0.113.9/32"),
+	})
+
+	netblock.Minute = ratelimit.Buckets{Start: halfAnHourOn, Current: 1}
+	netblock.Hour.Current = 8
+	want := []anomaly.Counter{netblock, {
+		Scope:  anomaly.ScopeTotal,
+		Minute: ratelimit.Buckets{Start: halfAnHourOn, Current: 1},
+	}}
+
+	if got := counters.Snapshot(); !reflect.DeepEqual(got, want) {
+		t.Errorf("counters after a request\n%+v\nwant\n%+v", got, want)
+	}
+}
+
+func TestLoadDropsTheLeastRecentlyCountedFirst(t *testing.T) {
+	t.Parallel()
+
+	counters := newCounters(anomaly.Params{
+		Client: anomaly.Thresholds{RequestsPerMinute: 1000},
+	})
+	now := midnight().Add(time.Minute)
+
+	// The second half of the file was counted in the minute before the
+	// first half.
+	read := make([]anomaly.Counter, 0, maxCounters)
+	for i := range maxCounters {
+		start := now
+		if i >= maxCounters/2 {
+			start = midnight()
+		}
+
+		read = append(read, anomaly.Counter{
+			Scope: anomaly.ScopeClient, Netblock: request(i).ClientGroup,
+			Minute: ratelimit.Buckets{Start: start, Current: 1},
+		})
+	}
+
+	counters.Load(read, now)
+	counters.Count(now, request(maxCounters))
+
+	got := counters.Snapshot()
+	if !holds(got, 0) || holds(got, maxCounters/2) {
+		t.Errorf("holding the first client of the file %v, and the first counted in "+
+			"the minute before %v, want only the first", holds(got, 0),
+			holds(got, maxCounters/2))
+	}
+}
+
+// midnight is the time of the tests' requests.
+func midnight() time.Time {
+	return time.Date(2026, 10, 6, 0, 0, 0, 0, time.UTC)
+}
+
+// newCounters returns Counters for params, whose alerts go nowhere.
+func newCounters(params anomaly.Params) *anomaly.Counters {
+	params.Alerts = alerts.New(alerts.Params{})
+
+	return anomaly.New(params)
+}
+
+// newQueue returns a queue of alerts to a webhook, with the default
+// cooldown, which keeps them waiting, since it is never run.
+func newQueue() *alerts.Queue {
+	return alerts.New(alerts.Params{
+		WebhookURL: &url.URL{Scheme: "https", Host: "alerts.example"},
+		Events:     alerts.Events(),
+		Cooldown:   15 * time.Minute,
+		MaxPerHour: 60,
+		Now:        midnight,
+	})
+}
+
+// request returns a request from client number i, an address in
+// 10.0.0.0/8.
+func request(i int) anomaly.Request {
+	client := netip.MustParseAddr(fmt.Sprintf("10.%d.%d.%d", i>>16, i>>8&255, i&255))
+
+	return anomaly.Request{Client: client, ClientGroup: netip.PrefixFrom(client, 32)}
+}
+
+// holds reports whether counters hold the counter of client number i.
+func holds(counters []anomaly.Counter, i int) bool {
+	return slices.ContainsFunc(counters, func(counter anomaly.Counter) bool {
+		return counter.Netblock == request(i).ClientGroup
+	})
+}

internal/bans/admin_test.go

@@ -66,12 +66,15 @@ func TestReasonOfTheBansSmallwebwafMakes(t *testing.T) {
 	ledger := bans.New(defaultRules())
 
 	limit, _ := ledger.BanForLimit(netip.MustParsePrefix("203.0.113.1/32"), midnight(),
-		bans.Notes{Limit: 1000, Window: "minute"})
+		bans.Notes{Kind: "requests", Limit: 1000, Window: "minute"})
+	byteLimit, _ := ledger.BanForLimit(netip.MustParsePrefix("203.0.113.3/32"),
+		midnight(), bans.Notes{Kind: "bytes", Limit: 10 << 30, Window: "hour"})
 	attack, _ := ledger.BanForAttack(netip.MustParsePrefix("203.0.113.2/32"), midnight(),
 		bans.Notes{RuleID: "git-dir", Target: "path"})
 
 	for _, tc := range []struct{ got, want string }{
 		{limit.Reason, "requests per minute over the limit of 1000"},
+		{byteLimit.Reason, "bytes per hour over the limit of 10737418240"},
 		{attack.Reason, "matched the rule git-dir"},
 	} {
 		if tc.got != tc.want {

internal/bans/bans.go

@@ -1,8 +1,8 @@
 // Package bans is the ban ledger: the bans smallwebwaf makes on the
-// netblocks of clients that break a rate limit or show a clear sign of
-// attack, and those an admin makes, with their notes, as the "Bans"
-// section of SPEC.md describes. The bans are kept in memory, and written
-// to bans.json and read from it by the state package.
+// netblocks of clients that break a rate limit or a byte limit or show a
+// clear sign of attack, and those an admin makes, with their notes, as
+// the "Bans" section of SPEC.md describes. The bans are kept in memory,
+// and written to bans.json and read from it by the state package.
 package bans
 
 import (
@@ -97,20 +97,29 @@ type Notes struct {
 	ASN     string `json:"asn"`
 	ASName  string `json:"as_name"`
 	Country string `json:"country"`
-	// Limit, Window and Count are, for a ban for a broken limit, the limit
-	// that was broken, its window, "minute", "hour" or "day", and the
-	// count reached: the client's requests in the window, the one that
-	// broke the limit included. These are the requests that counted
-	// toward the ban, and the window is the time over which they came.
+	// Kind, Limit, Window and Count are, for a ban for a broken limit,
+	// what the limit was on, "requests" for a rate limit or "bytes" for a
+	// byte limit, the limit that was broken, its window, "minute", "hour"
+	// or "day", and the count reached: the client's requests, or bytes, in
+	// the window, those of the request that broke the limit included.
+	// These are what counted toward the ban, and the window is the time
+	// over which they came.
+	Kind   string  `json:"kind,omitempty"`
 	Limit  int64   `json:"limit,omitempty"`
 	Window string  `json:"window,omitempty"`
 	Count  float64 `json:"count,omitempty"`
+	// LimitPercent and LimitPercentSetting are, for a ban for a limit a
+	// biased threshold lowered, the client's percentage of that kind of
+	// limit, of which Limit is the result, and the setting that gave it.
+	// Both are left out for a limit that was not lowered.
+	LimitPercent        *int64 `json:"limit_percent,omitempty"`
+	LimitPercentSetting string `json:"limit_percent_setting,omitempty"`
 	// RuleID and Target are, for a ban for a clear sign of attack, the id
 	// of the rule file rule that matched, and its target.
 	RuleID string `json:"rule_id,omitempty"`
 	Target string `json:"target,omitempty"`
-	// Request is the request that broke the limit, or that was the clear
-	// sign of attack.
+	// Request is the request that broke the limit, or whose bytes broke
+	// it, or that was the clear sign of attack.
 	Request Request `json:"request"`
 	// Requests is how many requests the netblock has sent since it was
 	// first seen, and Refused how many of them the ban has refused so
@@ -260,7 +269,8 @@ func activeBan(bans []Ban, now time.Time) *Ban {
 // active, as when two of its requests break a limit at once, that ban is
 // returned with false, and no other is made. The ledger fills in the
 // notes' Refused and EarlierBans itself, and gives the ban the reason
-// "requests per <Window> over the limit of <Limit>", from the notes.
+// "<Kind> per <Window> over the limit of <Limit>", from the notes, such
+// as "requests per minute over the limit of 1000".
 func (l *Ledger) BanForLimit(
 	netblock netip.Prefix, now time.Time, notes Notes,
 ) (Ban, bool) {
@@ -317,7 +327,8 @@ func (l *Ledger) WouldBePermanent(
 
 // limitReason is the reason of a ban for a broken limit, with notes.
 func limitReason(notes Notes) string {
-	return fmt.Sprintf("requests per %s over the limit of %d", notes.Window, notes.Limit)
+	return fmt.Sprintf("%s per %s over the limit of %d",
+		notes.Kind, notes.Window, notes.Limit)
 }
 
 // attackReason is the reason of a ban for a clear sign of attack, with

internal/bans/bans_test.go

@@ -349,7 +349,7 @@ func TestWouldBanGivesTheBanWithoutMakingIt(t *testing.T) {
 
 	// As it ends, a clear sign of attack would ban for seven days, and a
 	// limit broken again for three hours, but neither is made.
-	limitNotes := bans.Notes{Limit: 1, Window: "minute"}
+	limitNotes := bans.Notes{Kind: "requests", Limit: 1, Window: "minute"}
 	attack, wouldAttack := ledger.WouldBanForAttack(netblock, first.Expires,
 		bans.Notes{RuleID: "git-dir"})
 	limit, wouldLimit := ledger.WouldBanForLimit(netblock, first.Expires, limitNotes)

internal/config/config.go

@@ -24,6 +24,7 @@ import (
 	"unicode/utf8"
 
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/anomaly"
 	"sneak.berlin/go/smallwebwaf/internal/remotelog"
 )
 
@@ -91,6 +92,15 @@ type Config struct {
 	// limits neither count nor refuse (SWWAF_RATE_LIMIT_EXEMPT_PATHS).
 	// Each starts with /.
 	RateLimitExemptPaths []string
+	// BytesLimitPerMinute, BytesLimitPerHour and BytesLimitPerDay are the
+	// most bytes a client's requests may carry in a minute, an hour and a
+	// day (SWWAF_BYTES_LIMIT_PER_MINUTE, SWWAF_BYTES_LIMIT_PER_HOUR and
+	// SWWAF_BYTES_LIMIT_PER_DAY). BytesCount is which body bytes count
+	// toward them (SWWAF_BYTES_COUNT): response, request or both.
+	BytesLimitPerMinute int64
+	BytesLimitPerHour   int64
+	BytesLimitPerDay    int64
+	BytesCount          string
 	// LookupSource is where each client's AS number and country are
 	// looked up (SWWAF_LOOKUP_SOURCE): geojs, file, or off for nowhere.
 	// LookupDBPath is the lookup database, the IPinfo Lite file looked up
@@ -111,6 +121,60 @@ type Config struct {
 	// capitals, as GeoJS gives them.
 	DeniedCountries             []string
 	ExclusivelyAllowedCountries []string
+	// The biased thresholds. ASNLimitPercent and CountryLimitPercent give
+	// the clients of the AS numbers and the countries they list that
+	// percentage of every rate limit and byte limit
+	// (SWWAF_ASN_LIMIT_PERCENT and SWWAF_COUNTRY_LIMIT_PERCENT).
+	// ASNBytesPercent and CountryBytesPercent give those they list a
+	// percentage of the byte limits in place of that one
+	// (SWWAF_ASN_BYTES_PERCENT and SWWAF_COUNTRY_BYTES_PERCENT). Each holds
+	// percentages from 0 to 100, by AS number, written as AS64496, or by
+	// country, a two-letter code in capitals, as the lookup gives them.
+	// UnknownLimitPercent is the percentage of every limit a client without
+	// a country gets (SWWAF_UNKNOWN_LIMIT_PERCENT). ASNLimitPercentURL is
+	// where a file of AS:percent lines is fetched from, whose percentages
+	// count as those of ASNLimitPercent do (SWWAF_ASN_LIMIT_PERCENT_URL), ""
+	// while it is unset.
+	ASNLimitPercent     map[string]int64
+	CountryLimitPercent map[string]int64
+	ASNBytesPercent     map[string]int64
+	CountryBytesPercent map[string]int64
+	UnknownLimitPercent int64
+	ASNLimitPercentURL  string
+	// BlocklistURLs are where the blocklists are fetched from
+	// (SWWAF_BLOCKLIST_URLS). Each list, and ASNLimitPercentURL's, is
+	// fetched again BlocklistRefresh after it was last fetched or tried
+	// (SWWAF_BLOCKLIST_REFRESH), which is never less than an hour.
+	// BlocklistAction is what is done with a client a blocklist lists
+	// (SWWAF_BLOCKLIST_ACTION): deny, limit or log; for limit,
+	// BlocklistLimitPercent is the percentage of every limit it gets.
+	BlocklistURLs         []string
+	BlocklistRefresh      time.Duration
+	BlocklistAction       string
+	BlocklistLimitPercent int64
+	// DNSBLZones are the DNSBL zones clients are asked about
+	// (SWWAF_DNSBL_ZONES), through DNSBLResolver (SWWAF_DNSBL_RESOLVER), or
+	// the host's resolver while that is the zero AddrPort.
+	// AbuseIPDBKey is the key of the AbuseIPDB account clients are checked
+	// with (SWWAF_ABUSEIPDB_KEY), "" while it is unset and none is. A score
+	// of AbuseIPDBMinScore or more is a hit (SWWAF_ABUSEIPDB_MIN_SCORE), and
+	// at most AbuseIPDBDailyBudget checks are made a day
+	// (SWWAF_ABUSEIPDB_DAILY_BUDGET).
+	// ReputationAction is what is done with a client a zone's verdict lists,
+	// or whose score is a hit (SWWAF_REPUTATION_ACTION): deny, limit or log;
+	// for limit, ReputationLimitPercent is the percentage of every limit it
+	// gets. A verdict or a score is used for ReputationCacheTTL after it was
+	// fetched (SWWAF_REPUTATION_CACHE_TTL), and a query or a check may take
+	// ReputationTimeout (SWWAF_REPUTATION_TIMEOUT). Neither can be off.
+	DNSBLZones             []string
+	DNSBLResolver          netip.AddrPort
+	AbuseIPDBKey           string
+	AbuseIPDBMinScore      int64
+	AbuseIPDBDailyBudget   int
+	ReputationAction       string
+	ReputationLimitPercent int64
+	ReputationCacheTTL     time.Duration
+	ReputationTimeout      time.Duration
 	// BanResponse is the status a refused client is answered with, 403
 	// or 429, or 0 to close the connection without an answer
 	// (SWWAF_BAN_RESPONSE). It answers a banned client, a request that
@@ -195,6 +259,23 @@ type Config struct {
 	AlertEvents          []string
 	AlertCooldown        time.Duration
 	AlertMaxPerHour      int
+	// The anomaly thresholds, which only raise alerts: the most requests
+	// and bytes a minute and an hour per client (SWWAF_ANOMALY_CLIENT_*),
+	// per netblock around a client (SWWAF_ANOMALY_NET_*), per AS number
+	// (SWWAF_ANOMALY_ASN_*), for the whole service (SWWAF_ANOMALY_TOTAL_*)
+	// and per named netblock (SWWAF_WATCH_*), each 0 while it is off.
+	// AnomalyNetV4Prefix and AnomalyNetV6Prefix are the lengths of the
+	// netblock around a client (SWWAF_ANOMALY_NET_V4_PREFIX and
+	// SWWAF_ANOMALY_NET_V6_PREFIX), and WatchNets the named netblocks
+	// (SWWAF_WATCH_NETS).
+	AnomalyClient      anomaly.Thresholds
+	AnomalyNet         anomaly.Thresholds
+	AnomalyASN         anomaly.Thresholds
+	AnomalyTotal       anomaly.Thresholds
+	AnomalyWatch       anomaly.Thresholds
+	AnomalyNetV4Prefix int
+	AnomalyNetV6Prefix int
+	WatchNets          []anomaly.NamedNetblock
 
 	// settings are the values read, as given or by default, and the
 	// files they were read from, for the log line at start.
@@ -215,6 +296,7 @@ const (
 	mebibyte = 1 << 20
 	gibibyte = 1 << 30
 	ipv4Bits = 32
+	ipv6Bits = 128
 	// minTokenLength is the fewest characters a token may have.
 	minTokenLength = 32
 	// masked is what the log shows for a token that is set, and in place of
@@ -262,10 +344,15 @@ var (
 	errNotBanResponse = errors.New("is not 403, 429 or close")
 	errNotV4Prefix    = errors.New(
 		"is not the length of an IPv4 netblock, from 0 to 32, such as 24")
+	errNotV6Prefix = errors.New(
+		"is not the length of an IPv6 netblock, from 0 to 128, such as 48")
+	errNotNamedNetblock = errors.New(
+		"is not a name, = and a netblock, such as office=203.0.113.0/24")
 	errNotAbsolutePath = errors.New(
 		"is not an absolute path, such as /var/lib/smallwebwaf")
 	errShortToken    = errors.New("is shorter than 32 characters")
 	errNotMode       = errors.New("is not enforce or observe")
+	errNotBytesCount = errors.New("is not response, request or both")
 	errNotPathPrefix = errors.New(
 		"is not a path prefix starting with /, such as /assets/")
 	errNotBoolean      = errors.New("is not true or false")
@@ -290,6 +377,23 @@ var (
 			"source_failure or file_error")
 	errNotNumberOrOff = errors.New("is not a whole number above zero, such as 60, or off")
 	errNotUTF8        = errors.New("is not valid UTF-8")
+	errNotASN         = errors.New("is not an AS number such as AS64496")
+	errNotPercentItem = errors.New(
+		"is not a code, : and a percentage, such as AS64496:50 or cn:25")
+	errNotPercent  = errors.New("is not a percentage, a whole number from 0 to 100")
+	errListedTwice = errors.New("is listed twice")
+	errNotListURL  = errors.New(
+		"is not an http or https URL without a user or a fragment, " +
+			"such as https://www.spamhaus.org/drop/drop.txt")
+	errInBlocklistURLs = errors.New("is in SWWAF_BLOCKLIST_URLS too")
+	errNotAnHourOrMore = errors.New("is not a duration of 1h or more, such as 24h")
+	errNotAction       = errors.New(
+		"is not deny, limit:<percent> such as limit:25, or log")
+	errNotZone     = errors.New("is not a DNS zone such as dnsbl.dronebl.org")
+	errZoneTooLong = errors.New("is longer than 189 characters, too long for the " +
+		"names IPv6 clients are asked about by")
+	errNotResolver = errors.New("is not an IP address with an optional port, " +
+		"such as 192.0.2.53 or [2001:db8::53]:5353")
 )
 
 // FromEnvironment reads the settings with lookupEnv, normally
@@ -297,6 +401,8 @@ var (
 // named by the setting's name with _FILE added names the file, which is
 // read now (see lookup). A setting that is not set takes its default. A
 // setting that is set but invalid is an error that names it.
+//
+//nolint:funlen // one line for each setting, a list that grows with them
 func FromEnvironment(lookupEnv func(string) (string, bool)) (*Config, error) {
 	env := &environment{lookupEnv: lookupEnv}
 	cfg := &Config{
@@ -321,6 +427,10 @@ func FromEnvironment(lookupEnv func(string) (string, bool)) (*Config, error) {
 		RateLimitPerHour:        env.count("SWWAF_RATE_LIMIT_PER_HOUR", "10000"),
 		RateLimitPerDay:         env.count("SWWAF_RATE_LIMIT_PER_DAY", "50000"),
 		RateLimitExemptPaths:    env.pathPrefixes("SWWAF_RATE_LIMIT_EXEMPT_PATHS", ""),
+		BytesLimitPerMinute:     env.size("SWWAF_BYTES_LIMIT_PER_MINUTE", "10G"),
+		BytesLimitPerHour:       env.size("SWWAF_BYTES_LIMIT_PER_HOUR", "20G"),
+		BytesLimitPerDay:        env.size("SWWAF_BYTES_LIMIT_PER_DAY", "50G"),
+		BytesCount:              env.bytesCount("SWWAF_BYTES_COUNT", "both"),
 		LookupSource:            env.lookupSource("SWWAF_LOOKUP_SOURCE", "geojs"),
 		LookupDBPath:            env.value("SWWAF_LOOKUP_DB_PATH", ""),
 		LookupTimeout:           env.durationNotOff("SWWAF_LOOKUP_TIMEOUT", "1s"),
@@ -328,6 +438,21 @@ func FromEnvironment(lookupEnv func(string) (string, bool)) (*Config, error) {
 		DeniedCountries:         env.countries("SWWAF_DENIED_COUNTRIES", ""),
 		ExclusivelyAllowedCountries: env.countries(
 			"SWWAF_EXCLUSIVELY_ALLOWED_COUNTRIES", ""),
+		ASNLimitPercent:      env.percents("SWWAF_ASN_LIMIT_PERCENT", ParseASN),
+		CountryLimitPercent:  env.percents("SWWAF_COUNTRY_LIMIT_PERCENT", parseCountry),
+		ASNBytesPercent:      env.percents("SWWAF_ASN_BYTES_PERCENT", ParseASN),
+		CountryBytesPercent:  env.percents("SWWAF_COUNTRY_BYTES_PERCENT", parseCountry),
+		UnknownLimitPercent:  env.percent("SWWAF_UNKNOWN_LIMIT_PERCENT", "100"),
+		ASNLimitPercentURL:   env.listURL("SWWAF_ASN_LIMIT_PERCENT_URL"),
+		BlocklistURLs:        env.listURLs("SWWAF_BLOCKLIST_URLS"),
+		BlocklistRefresh:     env.refresh("SWWAF_BLOCKLIST_REFRESH", "24h"),
+		DNSBLZones:           env.zones("SWWAF_DNSBL_ZONES"),
+		DNSBLResolver:        env.resolver("SWWAF_DNSBL_RESOLVER"),
+		AbuseIPDBKey:         env.secret("SWWAF_ABUSEIPDB_KEY"),
+		AbuseIPDBMinScore:    env.percent("SWWAF_ABUSEIPDB_MIN_SCORE", "75"),
+		AbuseIPDBDailyBudget: env.numberNotOff("SWWAF_ABUSEIPDB_DAILY_BUDGET", "900"),
+		ReputationCacheTTL:   env.durationNotOff("SWWAF_REPUTATION_CACHE_TTL", "24h"),
+		ReputationTimeout:    env.durationNotOff("SWWAF_REPUTATION_TIMEOUT", "2s"),
 		BanResponse:          env.banResponse("SWWAF_BAN_RESPONSE", "403"),
 		LimitBanDuration:     env.durationNotOff("SWWAF_LIMIT_BAN_DURATION", "1h"),
 		LimitBanRepeatWindow: env.durationNotOff("SWWAF_LIMIT_BAN_REPEAT_WINDOW", "24h"),
@@ -356,16 +481,29 @@ func FromEnvironment(lookupEnv func(string) (string, bool)) (*Config, error) {
 		AlertNtfyToken:       env.secret("SWWAF_ALERT_NTFY_TOKEN"),
 		AlertEvents: env.alertEvents("SWWAF_ALERT_EVENTS",
 			strings.Join(alerts.Events(), ",")),
-		AlertCooldown:   env.duration("SWWAF_ALERT_COOLDOWN", "15m"),
-		AlertMaxPerHour: env.numberOrOff("SWWAF_ALERT_MAX_PER_HOUR", "60"),
+		AlertCooldown:      env.duration("SWWAF_ALERT_COOLDOWN", "15m"),
+		AlertMaxPerHour:    env.numberOrOff("SWWAF_ALERT_MAX_PER_HOUR", "60"),
+		AnomalyClient:      env.thresholds("SWWAF_ANOMALY_CLIENT_"),
+		AnomalyNet:         env.thresholds("SWWAF_ANOMALY_NET_"),
+		AnomalyASN:         env.thresholds("SWWAF_ANOMALY_ASN_"),
+		AnomalyTotal:       env.thresholds("SWWAF_ANOMALY_TOTAL_"),
+		AnomalyWatch:       env.thresholds("SWWAF_WATCH_"),
+		AnomalyNetV4Prefix: env.v4Prefix("SWWAF_ANOMALY_NET_V4_PREFIX", "24"),
+		AnomalyNetV6Prefix: env.v6Prefix("SWWAF_ANOMALY_NET_V6_PREFIX", "48"),
+		WatchNets:          env.namedNetblocks("SWWAF_WATCH_NETS"),
 	}
 
 	cfg.LogRemoteAppName = env.appName("SWWAF_LOG_REMOTE_APP_NAME",
 		cfg.InstanceName, cfg.LogRemoteURL != nil)
+	cfg.BlocklistAction, cfg.BlocklistLimitPercent = env.action(
+		"SWWAF_BLOCKLIST_ACTION", "deny")
+	cfg.ReputationAction, cfg.ReputationLimitPercent = env.action(
+		"SWWAF_REPUTATION_ACTION", "limit:25")
 
 	env.checkInstanceNameForNtfy(cfg.InstanceName, cfg.AlertNtfyURL != nil)
 	env.checkLookupDBPath(cfg)
 	env.checkCountriesAndLookups(cfg)
+	env.checkASNLimitPercentURL(cfg)
 
 	if env.err != nil {
 		return nil, env.err
@@ -551,6 +689,17 @@ func (e *environment) count(name, defaultValue string) int64 {
 	return count
 }
 
+// bytesCount reads the setting that is which body bytes count toward the
+// byte limits: response, request or both.
+func (e *environment) bytesCount(name, defaultValue string) string {
+	value := e.value(name, defaultValue)
+	if value != "response" && value != "request" && value != "both" {
+		e.check(name, fmt.Errorf("%q %w", value, errNotBytesCount))
+	}
+
+	return value
+}
+
 // pathPrefixes reads a setting that is a list of path prefixes.
 func (e *environment) pathPrefixes(name, defaultValue string) []string {
 	prefixes, err := parsePathPrefixes(e.value(name, defaultValue))
@@ -567,6 +716,106 @@ func (e *environment) countries(name, defaultValue string) []string {
 	return countries
 }
 
+// percents reads a setting that is a list of AS numbers or countries,
+// which parseCode reads, each with a percentage. It is empty by default.
+func (e *environment) percents(
+	name string, parseCode func(string) (string, error),
+) map[string]int64 {
+	percents, err := parsePercents(e.value(name, ""), parseCode)
+	e.check(name, err)
+
+	return percents
+}
+
+// percent reads a setting that is a percentage, from 0 to 100.
+func (e *environment) percent(name, defaultValue string) int64 {
+	percent, err := ParsePercent(e.value(name, defaultValue))
+	e.check(name, err)
+
+	return percent
+}
+
+// listURL reads a setting that is the URL a list is fetched from, "" while
+// it is unset or empty.
+func (e *environment) listURL(name string) string {
+	value := e.value(name, "")
+	if value != "" && !isListURL(value) {
+		e.check(name, fmt.Errorf("%q %w", value, errNotListURL))
+	}
+
+	return value
+}
+
+// listURLs reads a setting that is a list of the URLs lists are fetched
+// from. It is empty by default.
+func (e *environment) listURLs(name string) []string {
+	urls, err := parseListURLs(e.value(name, ""))
+	e.check(name, err)
+
+	return urls
+}
+
+// refresh reads the setting that is how long after a list was last
+// fetched or tried it is fetched again: a duration of an hour or more,
+// since the Spamhaus lists may be fetched no more often, which cannot be
+// off.
+func (e *environment) refresh(name, defaultValue string) time.Duration {
+	value := e.value(name, defaultValue)
+
+	duration, err := parseDuration(value)
+	if err != nil || duration < time.Hour {
+		e.check(name, fmt.Errorf("%q %w", value, errNotAnHourOrMore))
+	}
+
+	return duration
+}
+
+// action reads a setting that is what is done with a client a blocklist
+// or a DNSBL zone lists: deny, log, or limit:<percent>, which it returns
+// as limit and the percentage.
+func (e *environment) action(name, defaultValue string) (string, int64) {
+	value := e.value(name, defaultValue)
+	if value == "deny" || value == "log" {
+		return value, 0
+	}
+
+	percentText, isLimit := strings.CutPrefix(value, "limit:")
+
+	percent, err := ParsePercent(percentText)
+	if !isLimit || err != nil {
+		e.check(name, fmt.Errorf("%q %w", value, errNotAction))
+	}
+
+	return "limit", percent
+}
+
+// zones reads the setting that is the list of DNSBL zones. It is empty by
+// default. The log shows each zone with its key masked, as MaskZoneKey
+// masks it.
+func (e *environment) zones(name string) []string {
+	value, _ := e.lookup(name)
+	zones, err := parseZones(value)
+	e.check(name, err)
+
+	logged := make([]string, len(zones))
+	for i, zone := range zones {
+		logged[i] = MaskZoneKey(zone)
+	}
+
+	e.settings = append(e.settings, slog.String(name, strings.Join(logged, ",")))
+
+	return zones
+}
+
+// resolver reads the setting that is the resolver the DNSBL zones are
+// asked through, the zero AddrPort while it is unset or empty.
+func (e *environment) resolver(name string) netip.AddrPort {
+	resolver, err := parseResolver(e.value(name, ""))
+	e.check(name, err)
+
+	return resolver
+}
+
 // lookupSource reads the setting that is where clients are looked up:
 // geojs, file, or off.
 func (e *environment) lookupSource(name, defaultValue string) string {
@@ -594,7 +843,10 @@ func (e *environment) checkLookupDBPath(cfg *Config) {
 
 // checkCountriesAndLookups refuses a country on both country lists, and,
 // while SWWAF_LOOKUP_SOURCE is off, each setting that needs clients looked
-// up: the country lists and SWWAF_ADD_LOOKUP_HEADERS.
+// up: the country lists, SWWAF_ADD_LOOKUP_HEADERS, the biased thresholds,
+// SWWAF_ASN_LIMIT_PERCENT_URL among them, of which
+// SWWAF_UNKNOWN_LIMIT_PERCENT needs them only below 100, where it lowers a
+// limit, and the anomaly thresholds per AS number.
 func (e *environment) checkCountriesAndLookups(cfg *Config) {
 	for _, country := range cfg.ExclusivelyAllowedCountries {
 		if slices.Contains(cfg.DeniedCountries, country) {
@@ -614,6 +866,16 @@ func (e *environment) checkCountriesAndLookups(cfg *Config) {
 		{"SWWAF_DENIED_COUNTRIES", len(cfg.DeniedCountries) > 0},
 		{"SWWAF_EXCLUSIVELY_ALLOWED_COUNTRIES", len(cfg.ExclusivelyAllowedCountries) > 0},
 		{"SWWAF_ADD_LOOKUP_HEADERS", cfg.AddLookupHeaders},
+		{"SWWAF_ASN_LIMIT_PERCENT", len(cfg.ASNLimitPercent) > 0},
+		{"SWWAF_COUNTRY_LIMIT_PERCENT", len(cfg.CountryLimitPercent) > 0},
+		{"SWWAF_ASN_BYTES_PERCENT", len(cfg.ASNBytesPercent) > 0},
+		{"SWWAF_COUNTRY_BYTES_PERCENT", len(cfg.CountryBytesPercent) > 0},
+		{"SWWAF_UNKNOWN_LIMIT_PERCENT", cfg.UnknownLimitPercent < 100},
+		{"SWWAF_ASN_LIMIT_PERCENT_URL", cfg.ASNLimitPercentURL != ""},
+		{"SWWAF_ANOMALY_ASN_REQUESTS_PER_MINUTE", cfg.AnomalyASN.RequestsPerMinute > 0},
+		{"SWWAF_ANOMALY_ASN_REQUESTS_PER_HOUR", cfg.AnomalyASN.RequestsPerHour > 0},
+		{"SWWAF_ANOMALY_ASN_BYTES_PER_MINUTE", cfg.AnomalyASN.BytesPerMinute > 0},
+		{"SWWAF_ANOMALY_ASN_BYTES_PER_HOUR", cfg.AnomalyASN.BytesPerHour > 0},
 	} {
 		if setting.set {
 			e.check(setting.name, fmt.Errorf("is set while SWWAF_LOOKUP_SOURCE is off; %w",
@@ -622,6 +884,15 @@ func (e *environment) checkCountriesAndLookups(cfg *Config) {
 	}
 }
 
+// checkASNLimitPercentURL refuses SWWAF_ASN_LIMIT_PERCENT_URL naming a
+// blocklist too: the file at a URL is fetched as one list or the other.
+func (e *environment) checkASNLimitPercentURL(cfg *Config) {
+	if slices.Contains(cfg.BlocklistURLs, cfg.ASNLimitPercentURL) {
+		e.check("SWWAF_ASN_LIMIT_PERCENT_URL",
+			fmt.Errorf("%q %w", cfg.ASNLimitPercentURL, errInBlocklistURLs))
+	}
+}
+
 // headerNames reads a setting that is a list of header names, and
 // returns them in lower case.
 func (e *environment) headerNames(name, defaultValue string) []string {
@@ -665,6 +936,35 @@ func (e *environment) v4Prefix(name, defaultValue string) int {
 	return length
 }
 
+// v6Prefix reads a setting that is the length of an IPv6 netblock.
+func (e *environment) v6Prefix(name, defaultValue string) int {
+	length, err := parseV6Prefix(e.value(name, defaultValue))
+	e.check(name, err)
+
+	return length
+}
+
+// thresholds reads the four anomaly thresholds whose settings' names
+// start with prefix: requests and bytes per minute and per hour. Each is
+// off by default.
+func (e *environment) thresholds(prefix string) anomaly.Thresholds {
+	return anomaly.Thresholds{
+		RequestsPerMinute: e.count(prefix+"REQUESTS_PER_MINUTE", off),
+		RequestsPerHour:   e.count(prefix+"REQUESTS_PER_HOUR", off),
+		BytesPerMinute:    e.size(prefix+"BYTES_PER_MINUTE", off),
+		BytesPerHour:      e.size(prefix+"BYTES_PER_HOUR", off),
+	}
+}
+
+// namedNetblocks reads a setting that is a list of named netblocks. It is
+// empty by default.
+func (e *environment) namedNetblocks(name string) []anomaly.NamedNetblock {
+	named, err := parseNamedNetblocks(e.value(name, ""))
+	e.check(name, err)
+
+	return named
+}
+
 // absolutePath reads a setting that is an absolute path.
 func (e *environment) absolutePath(name, defaultValue string) string {
 	path := e.value(name, defaultValue)
@@ -821,10 +1121,10 @@ func (e *environment) webhookHeaders(name string) http.Header {
 }
 
 // secret reads a setting that is a secret another service gave, such as
-// an ntfy token, "" while it is unset. It is sent in a header, which
-// cannot hold a control character, so one in it is an error. The log
-// shows ******** in place of a value that is not empty, and an error
-// shows none of it.
+// an ntfy token or an AbuseIPDB key, "" while it is unset. It is sent in
+// a header, which cannot hold a control character, so one in it is an
+// error. The log shows ******** in place of a value that is not empty, and
+// an error shows none of it.
 func (e *environment) secret(name string) string {
 	value, _ := e.lookup(name)
 
@@ -1006,6 +1306,16 @@ func parseV4Prefix(value string) (int, error) {
 	return n, nil
 }
 
+// parseV6Prefix reads the length of an IPv6 netblock, from 0 to 128.
+func parseV6Prefix(value string) (int, error) {
+	n, err := strconv.Atoi(value)
+	if err != nil || n < 0 || n > ipv6Bits {
+		return 0, fmt.Errorf("%q %w", value, errNotV6Prefix)
+	}
+
+	return n, nil
+}
+
 // parseList splits a comma-separated list and trims the spaces around
 // each item. An empty value is an empty list.
 func parseList(value string) ([]string, error) {
@@ -1034,7 +1344,7 @@ func parseNetblocks(value string) ([]netip.Prefix, error) {
 	netblocks := make([]netip.Prefix, 0, len(items))
 
 	for _, item := range items {
-		netblock, err := parseNetblock(item)
+		netblock, err := ParseNetblock(item)
 		if err != nil {
 			return nil, err
 		}
@@ -1045,9 +1355,10 @@ func parseNetblocks(value string) ([]netip.Prefix, error) {
 	return netblocks, nil
 }
 
-// parseNetblock reads a netblock in CIDR form, such as 10.0.0.0/8. A bare
-// address is a netblock of that address alone, a /32 or a /128.
-func parseNetblock(value string) (netip.Prefix, error) {
+// ParseNetblock reads a netblock in CIDR form, such as 10.0.0.0/8. A bare
+// address is a netblock of that address alone, a /32 or a /128. A
+// blocklist's lines are read with it too.
+func ParseNetblock(value string) (netip.Prefix, error) {
 	if strings.Contains(value, "/") {
 		netblock, err := netip.ParsePrefix(value)
 		if err != nil {
@@ -1065,6 +1376,42 @@ func parseNetblock(value string) (netip.Prefix, error) {
 	return netip.PrefixFrom(addr, addr.BitLen()), nil
 }
 
+// parseNamedNetblocks reads a comma-separated list of named netblocks,
+// each a name, = and a netblock, such as office=203.0.113.0/24. An empty
+// value is an empty list. A name listed twice is an error.
+func parseNamedNetblocks(value string) ([]anomaly.NamedNetblock, error) {
+	items, err := parseList(value)
+	if err != nil {
+		return nil, err
+	}
+
+	named := make([]anomaly.NamedNetblock, 0, len(items))
+
+	for _, item := range items {
+		name, netblockText, found := strings.Cut(item, "=")
+		name = strings.TrimSpace(name)
+
+		if !found || name == "" {
+			return nil, fmt.Errorf("%q %w", item, errNotNamedNetblock)
+		}
+
+		netblock, err := ParseNetblock(strings.TrimSpace(netblockText))
+		if err != nil {
+			return nil, err
+		}
+
+		if slices.ContainsFunc(named, func(n anomaly.NamedNetblock) bool {
+			return n.Name == name
+		}) {
+			return nil, fmt.Errorf("%q %w", name, errListedTwice)
+		}
+
+		named = append(named, anomaly.NamedNetblock{Name: name, Netblock: netblock})
+	}
+
+	return named, nil
+}
+
 // parsePathPrefixes reads a comma-separated list of path prefixes, each
 // starting with /.
 func parsePathPrefixes(value string) ([]string, error) {
@@ -1123,13 +1470,12 @@ func parseCountries(value string) ([]string, error) {
 		return nil, err
 	}
 
-	known := strings.Fields(countryCodes)
 	countries := make([]string, 0, len(items))
 
 	for _, item := range items {
-		country := strings.ToUpper(item)
-		if !slices.Contains(known, country) {
-			return nil, fmt.Errorf("%q %w", item, errNotCountry)
+		country, err := parseCountry(item)
+		if err != nil {
+			return nil, err
 		}
 
 		countries = append(countries, country)
@@ -1138,6 +1484,83 @@ func parseCountries(value string) ([]string, error) {
 	return countries, nil
 }
 
+// parseCountry reads a country code in either case, and returns it in
+// capitals.
+func parseCountry(value string) (string, error) {
+	country := strings.ToUpper(value)
+	if !slices.Contains(strings.Fields(countryCodes), country) {
+		return "", fmt.Errorf("%q %w", value, errNotCountry)
+	}
+
+	return country, nil
+}
+
+// ParseASN reads an AS number such as AS64496, in either case, and
+// returns it as the lookup gives it: AS and the number, in capitals and
+// without leading zeros. The file SWWAF_ASN_LIMIT_PERCENT_URL names is
+// read with it too.
+func ParseASN(value string) (string, error) {
+	digits, hasAS := strings.CutPrefix(strings.ToUpper(value), "AS")
+
+	number, err := strconv.ParseUint(digits, 10, 32)
+	if !hasAS || err != nil {
+		return "", fmt.Errorf("%q %w", value, errNotASN)
+	}
+
+	return "AS" + strconv.FormatUint(number, 10), nil
+}
+
+// parsePercents reads a comma-separated list of items, each an AS number
+// or a country, which parseCode reads, then : and a percentage, such as
+// AS64496:50 or cn:25, and returns each one's percentage. An empty value
+// is an empty list. An AS number or country listed twice is an error.
+func parsePercents(
+	value string, parseCode func(string) (string, error),
+) (map[string]int64, error) {
+	items, err := parseList(value)
+	if err != nil {
+		return nil, err
+	}
+
+	percents := make(map[string]int64, len(items))
+
+	for _, item := range items {
+		codeText, percentText, found := strings.Cut(item, ":")
+		if !found {
+			return nil, fmt.Errorf("%q %w", item, errNotPercentItem)
+		}
+
+		code, err := parseCode(codeText)
+		if err != nil {
+			return nil, err
+		}
+
+		percent, err := ParsePercent(percentText)
+		if err != nil {
+			return nil, err
+		}
+
+		if _, listed := percents[code]; listed {
+			return nil, fmt.Errorf("%q %w", codeText, errListedTwice)
+		}
+
+		percents[code] = percent
+	}
+
+	return percents, nil
+}
+
+// ParsePercent reads a percentage, a whole number from 0 to 100. The file
+// SWWAF_ASN_LIMIT_PERCENT_URL names is read with it too.
+func ParsePercent(value string) (int64, error) {
+	percent, err := strconv.ParseInt(value, 10, 64)
+	if err != nil || percent < 0 || percent > 100 {
+		return 0, fmt.Errorf("%q %w", value, errNotPercent)
+	}
+
+	return percent, nil
+}
+
 // headerNameChars are the characters RFC 9110 allows in a header name:
 // letters, digits and these marks.
 const headerNameChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" +
@@ -1285,16 +1708,7 @@ func parseWebhookURL(value string) (*url.URL, string, error) {
 	}
 
 	webhook, err := url.Parse(value)
-	if err != nil {
-		return nil, "", errNotWebhookURL
-	}
-
-	port, err := strconv.ParseUint(webhook.Port(), 10, 16)
-
-	valid := (webhook.Scheme == "http" || webhook.Scheme == "https") &&
-		webhook.Hostname() != "" && (webhook.Port() == "" || (err == nil && port != 0)) &&
-		webhook.User == nil && webhook.Opaque == "" && webhook.Fragment == ""
-	if !valid {
+	if err != nil || !isHTTPURL(webhook) {
 		return nil, "", errNotWebhookURL
 	}
 
@@ -1306,6 +1720,154 @@ func parseWebhookURL(value string) (*url.URL, string, error) {
 	return webhook, logged, nil
 }
 
+// isHTTPURL reports whether u is http or https, with a host, and an
+// optional port from 1 to 65535, path and query, without a user or a
+// fragment.
+func isHTTPURL(u *url.URL) bool {
+	port, err := strconv.ParseUint(u.Port(), 10, 16)
+
+	return (u.Scheme == "http" || u.Scheme == "https") && u.Hostname() != "" &&
+		(u.Port() == "" || (err == nil && port != 0)) &&
+		u.User == nil && u.Opaque == "" && u.Fragment == ""
+}
+
+// isListURL reports whether value is a URL a list can be fetched from, as
+// isHTTPURL says.
+func isListURL(value string) bool {
+	u, err := url.Parse(value)
+
+	return err == nil && isHTTPURL(u)
+}
+
+// parseListURLs reads a comma-separated list of the URLs lists are fetched
+// from. A URL listed twice is an error: it would be fetched twice as
+// often.
+func parseListURLs(value string) ([]string, error) {
+	urls, err := parseList(value)
+	if err != nil {
+		return nil, err
+	}
+
+	for i, listURL := range urls {
+		if !isListURL(listURL) {
+			return nil, fmt.Errorf("%q %w", listURL, errNotListURL)
+		}
+
+		if slices.Contains(urls[:i], listURL) {
+			return nil, fmt.Errorf("%q %w", listURL, errListedTwice)
+		}
+	}
+
+	return urls, nil
+}
+
+const (
+	// maxZoneLength is the most characters a DNSBL zone may have: 253, the
+	// most a DNS name may have, less the 64 that come before the zone in
+	// the name an IPv6 client is asked about by, its 32 hex digits each
+	// followed by a dot.
+	maxZoneLength = 189
+	// maxLabelLength is the most characters a label of a DNS name may have.
+	maxLabelLength = 63
+	// labelChars are the characters a label of a DNS zone may hold.
+	labelChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-"
+	// dnsPort is the port a resolver is asked on when SWWAF_DNSBL_RESOLVER
+	// gives none.
+	dnsPort = 53
+)
+
+// parseZones reads a comma-separated list of DNSBL zones, each a DNS name
+// such as dnsbl.dronebl.org: labels separated by dots, each of 1 to 63
+// letters, digits and hyphens, neither starting nor ending with a hyphen,
+// and at most maxZoneLength characters in all. Go's resolver takes any
+// other name for one that does not exist, so that the zone would list no
+// client. A zone listed twice is an error, whatever the case of its
+// letters, which DNS names ignore, and whatever its key, since
+// MaskZoneKey shows two keys of one zone alike. An error shows a zone as
+// MaskZoneKey does.
+func parseZones(value string) ([]string, error) {
+	zones, err := parseList(value)
+	if err != nil {
+		// parseList's error, for an empty item, shows the whole value, keys
+		// included.
+		return nil, errEmptyItem
+	}
+
+	for i, zone := range zones {
+		shown := MaskZoneKey(zone)
+		listedBefore := slices.ContainsFunc(zones[:i], func(earlier string) bool {
+			return strings.EqualFold(MaskZoneKey(earlier), shown)
+		})
+
+		switch {
+		case len(zone) > maxZoneLength:
+			return nil, fmt.Errorf("%q %w", shown, errZoneTooLong)
+		case !isZone(zone):
+			return nil, fmt.Errorf("%q %w", shown, errNotZone)
+		case listedBefore:
+			return nil, fmt.Errorf("%q %w", shown, errListedTwice)
+		}
+	}
+
+	return zones, nil
+}
+
+// MaskZoneKey returns zone with ******** in place of its key, if it is a
+// zone of Spamhaus's keyed query service, a name under dq.spamhaus.net,
+// such as <key>.xbl.dq.spamhaus.net, whose first label is the key. Any
+// other zone it returns as it is. A zone is shown so wherever it leaves
+// the process: in the log, the alerts and the metrics.
+func MaskZoneKey(zone string) string {
+	// DNS names ignore case, and a name may be written with a dot at its
+	// end.
+	name := strings.TrimSuffix(strings.ToLower(zone), ".")
+	if !strings.HasSuffix(name, ".dq.spamhaus.net") {
+		return zone
+	}
+
+	_, rest, _ := strings.Cut(zone, ".")
+
+	return masked + "." + rest
+}
+
+// isZone reports whether each label of zone is as parseZones takes it.
+func isZone(zone string) bool {
+	for label := range strings.SplitSeq(zone, ".") {
+		badChar := strings.ContainsFunc(label, func(char rune) bool {
+			return !strings.ContainsRune(labelChars, char)
+		})
+
+		if label == "" || len(label) > maxLabelLength || badChar ||
+			strings.HasPrefix(label, "-") || strings.HasSuffix(label, "-") {
+			return false
+		}
+	}
+
+	return true
+}
+
+// parseResolver reads the resolver the DNSBL zones are asked through: an
+// IP address with a port from 1 to 65535, such as 192.0.2.53:5353 or
+// [2001:db8::53]:5353, or without one, such as 192.0.2.53 or 2001:db8::53,
+// for port 53. An empty value is none, the zero AddrPort.
+func parseResolver(value string) (netip.AddrPort, error) {
+	if value == "" {
+		return netip.AddrPort{}, nil
+	}
+
+	resolver, err := netip.ParseAddrPort(value)
+	if err == nil && resolver.Port() != 0 {
+		return resolver, nil
+	}
+
+	addr, err := netip.ParseAddr(value)
+	if err != nil {
+		return netip.AddrPort{}, fmt.Errorf("%q %w", value, errNotResolver)
+	}
+
+	return netip.AddrPortFrom(addr, dnsPort), nil
+}
+
 // parseWebhookHeaders reads a comma-separated list of headers, each its
 // name, :, and its value, and returns them, and how the log shows them,
 // with each value as ********. An error names the item by its place in

internal/config/config_test.go

@@ -12,10 +12,12 @@ import (
 	"path/filepath"
 	"reflect"
 	"slices"
+	"strconv"
 	"strings"
 	"testing"
 	"time"
 
+	"sneak.berlin/go/smallwebwaf/internal/anomaly"
 	"sneak.berlin/go/smallwebwaf/internal/config"
 )
 
@@ -40,12 +42,33 @@ const (
 	rateLimitPerHour        = "SWWAF_RATE_LIMIT_PER_HOUR"
 	rateLimitPerDay         = "SWWAF_RATE_LIMIT_PER_DAY"
 	rateLimitExemptPaths    = "SWWAF_RATE_LIMIT_EXEMPT_PATHS"
+	bytesLimitPerMinute     = "SWWAF_BYTES_LIMIT_PER_MINUTE"
+	bytesLimitPerHour       = "SWWAF_BYTES_LIMIT_PER_HOUR"
+	bytesLimitPerDay        = "SWWAF_BYTES_LIMIT_PER_DAY"
+	bytesCount              = "SWWAF_BYTES_COUNT"
 	lookupSource            = "SWWAF_LOOKUP_SOURCE"
 	lookupDBPath            = "SWWAF_LOOKUP_DB_PATH"
 	lookupTimeout           = "SWWAF_LOOKUP_TIMEOUT"
 	addLookupHeaders        = "SWWAF_ADD_LOOKUP_HEADERS"
 	deniedCountries         = "SWWAF_DENIED_COUNTRIES"
 	allowedCountries        = "SWWAF_EXCLUSIVELY_ALLOWED_COUNTRIES"
+	asnLimitPercent         = "SWWAF_ASN_LIMIT_PERCENT"
+	countryLimitPercent     = "SWWAF_COUNTRY_LIMIT_PERCENT"
+	asnBytesPercent         = "SWWAF_ASN_BYTES_PERCENT"
+	countryBytesPercent     = "SWWAF_COUNTRY_BYTES_PERCENT"
+	unknownLimitPercent     = "SWWAF_UNKNOWN_LIMIT_PERCENT"
+	asnLimitPercentURL      = "SWWAF_ASN_LIMIT_PERCENT_URL"
+	blocklistURLs           = "SWWAF_BLOCKLIST_URLS"
+	blocklistRefresh        = "SWWAF_BLOCKLIST_REFRESH"
+	blocklistAction         = "SWWAF_BLOCKLIST_ACTION"
+	dnsblZones              = "SWWAF_DNSBL_ZONES"
+	dnsblResolver           = "SWWAF_DNSBL_RESOLVER"
+	abuseIPDBKey            = "SWWAF_ABUSEIPDB_KEY"
+	abuseIPDBMinScore       = "SWWAF_ABUSEIPDB_MIN_SCORE"
+	abuseIPDBDailyBudget    = "SWWAF_ABUSEIPDB_DAILY_BUDGET"
+	reputationAction        = "SWWAF_REPUTATION_ACTION"
+	reputationCacheTTL      = "SWWAF_REPUTATION_CACHE_TTL"
+	reputationTimeout       = "SWWAF_REPUTATION_TIMEOUT"
 	banResponse             = "SWWAF_BAN_RESPONSE"
 	limitBanDuration        = "SWWAF_LIMIT_BAN_DURATION"
 	limitBanRepeatWindow    = "SWWAF_LIMIT_BAN_REPEAT_WINDOW"
@@ -76,8 +99,59 @@ const (
 	alertEvents             = "SWWAF_ALERT_EVENTS"
 	alertCooldown           = "SWWAF_ALERT_COOLDOWN"
 	alertMaxPerHour         = "SWWAF_ALERT_MAX_PER_HOUR"
+	anomalyNetV4Prefix      = "SWWAF_ANOMALY_NET_V4_PREFIX"
+	anomalyNetV6Prefix      = "SWWAF_ANOMALY_NET_V6_PREFIX"
+	watchNets               = "SWWAF_WATCH_NETS"
 )
 
+// The anomaly thresholds: each of the prefixes below, which name a scope,
+// followed by each of the four ends.
+const (
+	anomalyClient = "SWWAF_ANOMALY_CLIENT_"
+	anomalyNet    = "SWWAF_ANOMALY_NET_"
+	anomalyASN    = "SWWAF_ANOMALY_ASN_"
+	anomalyTotal  = "SWWAF_ANOMALY_TOTAL_"
+	watch         = "SWWAF_WATCH_"
+
+	requestsPerMinute = "REQUESTS_PER_MINUTE"
+	requestsPerHour   = "REQUESTS_PER_HOUR"
+	bytesPerMinute    = "BYTES_PER_MINUTE"
+	bytesPerHour      = "BYTES_PER_HOUR"
+)
+
+// anomalyScopes returns the prefixes of the anomaly thresholds, one for
+// each scope.
+func anomalyScopes() []string {
+	return []string{anomalyClient, anomalyNet, anomalyASN, anomalyTotal, watch}
+}
+
+// anomalyThresholds returns the names of the twenty anomaly thresholds.
+func anomalyThresholds() []string {
+	ends := []string{requestsPerMinute, requestsPerHour, bytesPerMinute, bytesPerHour}
+	names := make([]string, 0, len(anomalyScopes())*len(ends))
+
+	for _, scope := range anomalyScopes() {
+		for _, end := range ends {
+			names = append(names, scope+end)
+		}
+	}
+
+	return names
+}
+
+// loggedAnomalyDefaults returns the anomaly settings as the settings
+// logged at start give them by default.
+func loggedAnomalyDefaults() map[string]string {
+	logged := map[string]string{
+		anomalyNetV4Prefix: "24", anomalyNetV6Prefix: "48", watchNets: "",
+	}
+	for _, name := range anomalyThresholds() {
+		logged[name] = off
+	}
+
+	return logged
+}
+
 // defaultAlertEvents is the default of SWWAF_ALERT_EVENTS, and
 // defaultAlertCooldown that of SWWAF_ALERT_COOLDOWN.
 const (
@@ -86,6 +160,9 @@ const (
 	defaultAlertCooldown = "15m"
 )
 
+// defaultReputationCacheTTL is the default of SWWAF_REPUTATION_CACHE_TTL.
+const defaultReputationCacheTTL = "24h"
+
 // defaultLogRequestHeaders is the default of SWWAF_LOG_REQUEST_HEADERS.
 const defaultLogRequestHeaders = "accept,accept-language,accept-encoding," +
 	"content-type,origin,range"
@@ -190,6 +267,10 @@ func TestDefaults(t *testing.T) {
 	wantLookupSettings(t, cfg, config.Config{
 		LookupSource: defaultLookupSource, LookupTimeout: time.Second,
 	})
+	wantByteLimitSettings(t, cfg, config.Config{
+		BytesLimitPerMinute: 10 << 30, BytesLimitPerHour: 20 << 30,
+		BytesLimitPerDay: 50 << 30, BytesCount: "both",
+	})
 
 	if cfg.UpstreamURL.String() != "http://127.0.0.1:8081" {
 		t.Errorf("%s is %s", upstreamURL, cfg.UpstreamURL)
@@ -220,6 +301,22 @@ func TestDefaults(t *testing.T) {
 	}
 }
 
+func TestNoSingleRequestBreaksAByteLimitAtTheDefaults(t *testing.T) {
+	t.Parallel()
+
+	cfg := fromEnvironment(t, environment{})
+
+	// The largest request body and the largest response, both counted.
+	largest := cfg.RequestMaxBytes + cfg.ResponseMaxBytes
+	for _, limit := range []int64{
+		cfg.BytesLimitPerMinute, cfg.BytesLimitPerHour, cfg.BytesLimitPerDay,
+	} {
+		if largest > limit {
+			t.Errorf("a request of %d bytes breaks the byte limit of %d", largest, limit)
+		}
+	}
+}
+
 func TestValuesAsSet(t *testing.T) {
 	t.Parallel()
 
@@ -302,6 +399,22 @@ func TestValuesAsSet(t *testing.T) {
 	wantCountries(t, allowedCountries, cfg.ExclusivelyAllowedCountries, "DE")
 }
 
+func TestByteLimitSettingsAsSet(t *testing.T) {
+	t.Parallel()
+
+	cfg := fromEnvironment(t, environment{
+		bytesLimitPerMinute: "512M",
+		bytesLimitPerHour:   off,
+		bytesLimitPerDay:    "100000",
+		bytesCount:          "response",
+	})
+
+	wantByteLimitSettings(t, cfg, config.Config{
+		BytesLimitPerMinute: 512 << 20, BytesLimitPerHour: 0,
+		BytesLimitPerDay: 100000, BytesCount: "response",
+	})
+}
+
 func TestRateLimitExemptPathsAsSet(t *testing.T) {
 	t.Parallel()
 
@@ -852,9 +965,19 @@ func TestSettingNeedingLookupsStopsTheStartWhileTheyAreOff(t *testing.T) {
 	t.Parallel()
 
 	for name, value := range map[string]string{
-		deniedCountries:  "kp",
-		allowedCountries: "de",
-		addLookupHeaders: enabled,
+		deniedCountries:                "kp",
+		allowedCountries:               "de",
+		addLookupHeaders:               enabled,
+		asnLimitPercentURL:             asnURL,
+		asnLimitPercent:                "AS64496:50",
+		countryLimitPercent:            "cn:25",
+		asnBytesPercent:                "AS64496:50",
+		countryBytesPercent:            "cn:25",
+		unknownLimitPercent:            "99",
+		anomalyASN + requestsPerMinute: "1000",
+		anomalyASN + requestsPerHour:   "10000",
+		anomalyASN + bytesPerMinute:    "1G",
+		anomalyASN + bytesPerHour:      "10G",
 	} {
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
@@ -869,10 +992,611 @@ func TestSettingNeedingLookupsStopsTheStartWhileTheyAreOff(t *testing.T) {
 		})
 	}
 
-	// Set empty, the country lists need nothing looked up.
-	fromEnvironment(t, environment{
+	// Set empty, the lists need nothing looked up, and nor does
+	// SWWAF_UNKNOWN_LIMIT_PERCENT at 100, which lowers no limit, an anomaly
+	// threshold per AS number that is off, any other anomaly threshold, or
+	// a blocklist.
+	env := environment{
 		lookupSource: off, deniedCountries: "", allowedCountries: "",
+		asnLimitPercent: "", countryLimitPercent: "", asnBytesPercent: "",
+		countryBytesPercent: "", unknownLimitPercent: "100", asnLimitPercentURL: "",
+		blocklistURLs: dropURL,
+	}
+	for _, name := range anomalyThresholds() {
+		env[name] = "1000"
+		if strings.HasPrefix(name, anomalyASN) {
+			env[name] = off
+		}
+	}
+
+	fromEnvironment(t, env)
+}
+
+func TestAnomalySettingsDefaults(t *testing.T) {
+	t.Parallel()
+
+	cfg := fromEnvironment(t, environment{})
+	wantAllOff(t, cfg)
+
+	if cfg.AnomalyNetV4Prefix != 24 || cfg.AnomalyNetV6Prefix != 48 ||
+		len(cfg.WatchNets) != 0 {
+		t.Errorf("%s, %s and %s gave %d, %d and %v, want 24, 48 and none",
+			anomalyNetV4Prefix, anomalyNetV6Prefix, watchNets, cfg.AnomalyNetV4Prefix,
+			cfg.AnomalyNetV6Prefix, cfg.WatchNets)
+	}
+}
+
+func TestAnomalySettingsAsSet(t *testing.T) {
+	t.Parallel()
+
+	// Each threshold of a scope its own value; bytes are sizes.
+	env := environment{
+		anomalyNetV4Prefix: "16",
+		anomalyNetV6Prefix: "56",
+		// Spaces around a name or a netblock, and a bare address.
+		watchNets: "office = 203.0.113.0/24, scraper-x=198.51.100.7,v6=2001:db8::/32",
+	}
+	want := map[string]anomaly.Thresholds{}
+
+	for i, scope := range anomalyScopes() {
+		n := int64(i + 1)
+		env[scope+requestsPerMinute] = strconv.FormatInt(n, 10)
+		env[scope+requestsPerHour] = strconv.FormatInt(10*n, 10)
+		env[scope+bytesPerMinute] = strconv.FormatInt(n, 10) + "K"
+		env[scope+bytesPerHour] = strconv.FormatInt(n, 10) + "G"
+		want[scope] = anomaly.Thresholds{
+			RequestsPerMinute: n, RequestsPerHour: 10 * n,
+			BytesPerMinute: n << 10, BytesPerHour: n << 30,
+		}
+	}
+
+	cfg := fromEnvironment(t, env)
+
+	if got := thresholdsByScope(cfg); !maps.Equal(got, want) {
+		t.Errorf("thresholds by scope\n%+v\nwant\n%+v", got, want)
+	}
+
+	wantNamed := []anomaly.NamedNetblock{
+		{Name: "office", Netblock: netip.MustParsePrefix("203.0.113.0/24")},
+		{Name: "scraper-x", Netblock: netip.MustParsePrefix("198.51.100.7/32")},
+		{Name: "v6", Netblock: netip.MustParsePrefix("2001:db8::/32")},
+	}
+	if cfg.AnomalyNetV4Prefix != 16 || cfg.AnomalyNetV6Prefix != 56 ||
+		!slices.Equal(cfg.WatchNets, wantNamed) {
+		t.Errorf("%s, %s and %s gave %d, %d and %v, want 16, 56 and %v",
+			anomalyNetV4Prefix, anomalyNetV6Prefix, watchNets, cfg.AnomalyNetV4Prefix,
+			cfg.AnomalyNetV6Prefix, cfg.WatchNets, wantNamed)
+	}
+
+	// off switches each threshold off.
+	for _, name := range anomalyThresholds() {
+		env[name] = off
+	}
+
+	wantAllOff(t, fromEnvironment(t, env))
+}
+
+// thresholdsByScope returns cfg's anomaly thresholds, each by the prefix
+// of its scope's settings.
+func thresholdsByScope(cfg *config.Config) map[string]anomaly.Thresholds {
+	return map[string]anomaly.Thresholds{
+		anomalyClient: cfg.AnomalyClient, anomalyNet: cfg.AnomalyNet,
+		anomalyASN: cfg.AnomalyASN, anomalyTotal: cfg.AnomalyTotal,
+		watch: cfg.AnomalyWatch,
+	}
+}
+
+// wantAllOff checks that every anomaly threshold of cfg is off.
+func wantAllOff(t *testing.T, cfg *config.Config) {
+	t.Helper()
+
+	for scope, thresholds := range thresholdsByScope(cfg) {
+		if thresholds != (anomaly.Thresholds{}) {
+			t.Errorf("%s* gave %+v, want every one off", scope, thresholds)
+		}
+	}
+}
+
+func TestInvalidAnomalySettingStopsTheStartSayingWhatIsWrong(t *testing.T) {
+	t.Parallel()
+
+	const (
+		notCount        = " is not a whole number of requests such as 1000, or off"
+		notSize         = " is not a size such as 512K, 100M or 5G, or off"
+		notPositive     = " must be more than zero, or off"
+		notNamed        = " is not a name, = and a netblock, such as office=203.0.113.0/24"
+		notNetblock     = " is not a netblock such as 10.0.0.0/8, or an address"
+		notV4Prefix     = " is not the length of an IPv4 netblock, from 0 to 32, such as 24"
+		notV6Prefix     = " is not the length of an IPv6 netblock, from 0 to 128, such as 48"
+		officeNetblock  = "office=203.0.113.0/24"
+		scraperNetblock = "scraper=198.51.100.0/24"
+	)
+
+	for _, tc := range []struct{ name, value, want string }{
+		{anomalyClient + requestsPerMinute, "1K", `"1K"` + notCount},
+		{anomalyNet + requestsPerHour, "0", `"0"` + notPositive},
+		{anomalyTotal + bytesPerMinute, "1T", `"1T"` + notSize},
+		{watch + bytesPerHour, "-1G", `"-1G"` + notPositive},
+		{anomalyNetV4Prefix, "33", `"33"` + notV4Prefix},
+		{anomalyNetV4Prefix, off, `"off"` + notV4Prefix},
+		{anomalyNetV6Prefix, "129", `"129"` + notV6Prefix},
+		{anomalyNetV6Prefix, "/48", `"/48"` + notV6Prefix},
+		{watchNets, "office", `"office"` + notNamed},
+		{watchNets, "=203.0.113.0/24", `"=203.0.113.0/24"` + notNamed},
+		{watchNets, "office=203.0.113.300/24", `"203.0.113.300/24"` + notNetblock},
+		{watchNets, officeNetblock + ",", `"` + officeNetblock + `," has an empty item ` +
+			`in its list`},
+		{
+			watchNets, officeNetblock + "," + scraperNetblock + ",office=192.0.2.0/24",
+			`"office" is listed twice`,
+		},
+	} {
+		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+
+			want := tc.name + ": " + tc.want
+			if err == nil || err.Error() != want {
+				t.Errorf("error %v, want %s", err, want)
+			}
+		})
+	}
+}
+
+func TestBiasedThresholdsAsSet(t *testing.T) {
+	t.Parallel()
+
+	cfg := fromEnvironment(t, environment{})
+	if len(cfg.ASNLimitPercent) != 0 || len(cfg.CountryLimitPercent) != 0 ||
+		len(cfg.ASNBytesPercent) != 0 || len(cfg.CountryBytesPercent) != 0 ||
+		cfg.UnknownLimitPercent != 100 {
+		t.Errorf("biased thresholds %v, %v, %v, %v and %d by default, "+
+			"want four empty lists and 100", cfg.ASNLimitPercent, cfg.CountryLimitPercent,
+			cfg.ASNBytesPercent, cfg.CountryBytesPercent, cfg.UnknownLimitPercent)
+	}
+
+	// AS numbers and countries in either case, an AS number with leading
+	// zeros, 0 and 100.
+	cfg = fromEnvironment(t, environment{
+		asnLimitPercent:     "AS14061:50, as16276:0,AS045102:100",
+		countryLimitPercent: "cn:25,RU:50",
+		asnBytesPercent:     "as16276:75",
+		countryBytesPercent: "ru:10",
+		unknownLimitPercent: "0",
 	})
+
+	for name, tc := range map[string]struct{ got, want map[string]int64 }{
+		asnLimitPercent: {
+			cfg.ASNLimitPercent,
+			map[string]int64{"AS14061": 50, "AS16276": 0, "AS45102": 100},
+		},
+		countryLimitPercent: {cfg.CountryLimitPercent, map[string]int64{"CN": 25, "RU": 50}},
+		asnBytesPercent:     {cfg.ASNBytesPercent, map[string]int64{"AS16276": 75}},
+		countryBytesPercent: {cfg.CountryBytesPercent, map[string]int64{"RU": 10}},
+	} {
+		if !maps.Equal(tc.got, tc.want) {
+			t.Errorf("%s gave %v, want %v", name, tc.got, tc.want)
+		}
+	}
+
+	if cfg.UnknownLimitPercent != 0 {
+		t.Errorf("%s gave %d, want 0", unknownLimitPercent, cfg.UnknownLimitPercent)
+	}
+}
+
+func TestInvalidBiasedThresholdStopsTheStartSayingWhatIsWrong(t *testing.T) {
+	t.Parallel()
+
+	const (
+		notASN     = " is not an AS number such as AS64496"
+		notItem    = " is not a code, : and a percentage, such as AS64496:50 or cn:25"
+		notPercent = " is not a percentage, a whole number from 0 to 100"
+	)
+
+	for _, tc := range []struct{ name, value, want string }{
+		{asnLimitPercent, "14061:50", `"14061"` + notASN},
+		{asnLimitPercent, "AS4294967296:50", `"AS4294967296"` + notASN},
+		{asnLimitPercent, "AS14061", `"AS14061"` + notItem},
+		{asnLimitPercent, "AS14061:101", `"101"` + notPercent},
+		{asnLimitPercent, "AS14061:50,as14061:25", `"as14061" is listed twice`},
+		{
+			countryLimitPercent, "nk:25",
+			`"nk" is not a two-letter country code such as de or kp`,
+		},
+		{countryLimitPercent, "cn:25,CN:50", `"CN" is listed twice`},
+		{asnBytesPercent, "AS14061:-1", `"-1"` + notPercent},
+		{countryBytesPercent, "cn:50%", `"50%"` + notPercent},
+		{unknownLimitPercent, "101", `"101"` + notPercent},
+		{unknownLimitPercent, off, `"off"` + notPercent},
+	} {
+		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+
+			want := tc.name + ": " + tc.want
+			if err == nil || err.Error() != want {
+				t.Errorf("error %v, want %s", err, want)
+			}
+		})
+	}
+}
+
+// dropURL and torURL are blocklists, and asnURL a file of AS:percent
+// lines.
+const (
+	dropURL = "https://www.spamhaus.org/drop/drop.txt"
+	torURL  = "https://lists.example/tor-exits.txt"
+	asnURL  = "https://lists.example/asn.txt"
+)
+
+// The actions of SWWAF_BLOCKLIST_ACTION, as Config gives them.
+const (
+	actionDeny  = "deny"
+	actionLimit = "limit"
+	actionLog   = "log"
+)
+
+func TestReputationSettingsAsSet(t *testing.T) {
+	t.Parallel()
+
+	cfg := fromEnvironment(t, environment{})
+	if len(cfg.BlocklistURLs) != 0 || cfg.BlocklistRefresh != 24*time.Hour ||
+		cfg.BlocklistAction != actionDeny || cfg.ASNLimitPercentURL != "" {
+		t.Errorf("%s, %s, %s and %s gave %v, %s, %s and %q by default, "+
+			"want none, 24h, deny and none", blocklistURLs, blocklistRefresh,
+			blocklistAction, asnLimitPercentURL, cfg.BlocklistURLs, cfg.BlocklistRefresh,
+			cfg.BlocklistAction, cfg.ASNLimitPercentURL)
+	}
+
+	for _, tc := range []struct {
+		value, action string
+		percent       int64
+	}{
+		{actionDeny, actionDeny, 0},
+		{actionLog, actionLog, 0},
+		{"limit:25", actionLimit, 25},
+		{"limit:0", actionLimit, 0},
+	} {
+		// An hour, the shortest refresh allowed.
+		cfg := fromEnvironment(t, environment{
+			blocklistURLs: dropURL + ", " + torURL, blocklistRefresh: "1h",
+			blocklistAction: tc.value, asnLimitPercentURL: asnURL,
+		})
+
+		if !slices.Equal(cfg.BlocklistURLs, []string{dropURL, torURL}) ||
+			cfg.BlocklistRefresh != time.Hour || cfg.BlocklistAction != tc.action ||
+			cfg.BlocklistLimitPercent != tc.percent || cfg.ASNLimitPercentURL != asnURL {
+			t.Errorf("%s=%s gave %v, %s, %s, %d and %s", blocklistAction, tc.value,
+				cfg.BlocklistURLs, cfg.BlocklistRefresh, cfg.BlocklistAction,
+				cfg.BlocklistLimitPercent, cfg.ASNLimitPercentURL)
+		}
+	}
+}
+
+func TestInvalidReputationSettingStopsTheStartSayingWhatIsWrong(t *testing.T) {
+	t.Parallel()
+
+	const (
+		notURL = " is not an http or https URL without a user or a fragment, " +
+			"such as https://www.spamhaus.org/drop/drop.txt"
+		notAnHour = " is not a duration of 1h or more, such as 24h"
+		notAction = " is not deny, limit:<percent> such as limit:25, or log"
+	)
+
+	for _, tc := range []struct{ name, value, want string }{
+		{
+			blocklistURLs, "ftp://lists.example/drop.txt",
+			`"ftp://lists.example/drop.txt"` + notURL,
+		},
+		{blocklistURLs, "lists.example/drop.txt", `"lists.example/drop.txt"` + notURL},
+		{
+			blocklistURLs, "https://me:secret@lists.example/drop.txt",
+			`"https://me:secret@lists.example/drop.txt"` + notURL,
+		},
+		{
+			blocklistURLs, dropURL + "," + torURL + "," + dropURL,
+			`"` + dropURL + `" is listed twice`,
+		},
+		{asnLimitPercentURL, asnURL + "#top", `"` + asnURL + `#top"` + notURL},
+		{blocklistRefresh, "59m", `"59m"` + notAnHour},
+		{blocklistRefresh, off, `"off"` + notAnHour},
+		{blocklistRefresh, "a day", `"a day"` + notAnHour},
+		{blocklistAction, "block", `"block"` + notAction},
+		{blocklistAction, actionLimit, `"limit"` + notAction},
+		{blocklistAction, "limit:101", `"limit:101"` + notAction},
+	} {
+		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+
+			want := tc.name + ": " + tc.want
+			if err == nil || err.Error() != want {
+				t.Errorf("error %v, want %s", err, want)
+			}
+		})
+	}
+}
+
+func TestASNLimitPercentURLThatIsABlocklistStopsTheStart(t *testing.T) {
+	t.Parallel()
+
+	_, err := config.FromEnvironment(environment{
+		blocklistURLs: dropURL + "," + asnURL, asnLimitPercentURL: asnURL,
+	}.lookupEnv)
+
+	want := asnLimitPercentURL + `: "` + asnURL + `" is in SWWAF_BLOCKLIST_URLS too`
+	if err == nil || err.Error() != want {
+		t.Errorf("error %v, want %s", err, want)
+	}
+}
+
+// dronebl is a DNSBL zone, and spamhaus one of Spamhaus's, a name
+// containing spamhausKey, the key of its keyed query service, which the
+// log shows as spamhausMasked.
+const (
+	dronebl        = "dnsbl.dronebl.org"
+	spamhausKey    = "abcdefghijklmnopqrstuvwxyz"
+	spamhaus       = spamhausKey + ".xbl.dq.spamhaus.net"
+	spamhausMasked = "********.xbl.dq.spamhaus.net"
+)
+
+func TestDNSBLSettingsAsSet(t *testing.T) {
+	t.Parallel()
+
+	cfg := fromEnvironment(t, environment{})
+	if len(cfg.DNSBLZones) != 0 || cfg.DNSBLResolver.IsValid() ||
+		cfg.ReputationAction != actionLimit || cfg.ReputationLimitPercent != 25 ||
+		cfg.ReputationCacheTTL != 24*time.Hour || cfg.ReputationTimeout != 2*time.Second {
+		t.Errorf("by default, the zones %v, the resolver %s, the action %s:%d, the TTL %s "+
+			"and the timeout %s, want no zone, no resolver, limit:25, 24h and 2s",
+			cfg.DNSBLZones,
+			cfg.DNSBLResolver, cfg.ReputationAction, cfg.ReputationLimitPercent,
+			cfg.ReputationCacheTTL, cfg.ReputationTimeout)
+	}
+
+	// The longest zone allowed, of 189 characters, with labels of 63, the
+	// longest allowed.
+	longest := strings.Repeat("a", 63) + "." + strings.Repeat("b", 63) + "." +
+		strings.Repeat("c", 61)
+
+	for _, tc := range []struct {
+		zones, resolver, action string
+		// want are the zones, resolver, action and percent Config gives.
+		want         []string
+		wantResolver string
+		wantAction   string
+		wantPercent  int64
+	}{
+		{
+			dronebl + ", " + spamhaus, "192.0.2.53", actionDeny,
+			[]string{dronebl, spamhaus}, "192.0.2.53:53", actionDeny, 0,
+		},
+		{
+			longest, "192.0.2.53:5353", actionLog,
+			[]string{longest}, "192.0.2.53:5353", actionLog, 0,
+		},
+		{
+			"Dnsbl-1.Example", "2001:db8::53", "limit:10",
+			[]string{"Dnsbl-1.Example"}, "[2001:db8::53]:53", actionLimit, 10,
+		},
+		{
+			dronebl, "[2001:db8::53]:5353", "limit:0",
+			[]string{dronebl}, "[2001:db8::53]:5353", actionLimit, 0,
+		},
+	} {
+		cfg := fromEnvironment(t, environment{
+			dnsblZones: tc.zones, dnsblResolver: tc.resolver, reputationAction: tc.action,
+			reputationCacheTTL: "12h", reputationTimeout: "3s",
+		})
+
+		if !slices.Equal(cfg.DNSBLZones, tc.want) ||
+			cfg.DNSBLResolver.String() != tc.wantResolver ||
+			cfg.ReputationAction != tc.wantAction ||
+			cfg.ReputationLimitPercent != tc.wantPercent ||
+			cfg.ReputationCacheTTL != 12*time.Hour ||
+			cfg.ReputationTimeout != 3*time.Second {
+			t.Errorf("%s=%s, %s=%s and %s=%s gave %v, %s, %s:%d, %s and %s", dnsblZones,
+				tc.zones, dnsblResolver, tc.resolver, reputationAction, tc.action,
+				cfg.DNSBLZones, cfg.DNSBLResolver, cfg.ReputationAction,
+				cfg.ReputationLimitPercent, cfg.ReputationCacheTTL, cfg.ReputationTimeout)
+		}
+	}
+}
+
+func TestInvalidDNSBLSettingStopsTheStartSayingWhatIsWrong(t *testing.T) {
+	t.Parallel()
+
+	const (
+		notZone     = " is not a DNS zone such as dnsbl.dronebl.org"
+		notResolver = " is not an IP address with an optional port, such as 192.0.2.53 " +
+			"or [2001:db8::53]:5353"
+		notAboveZero = " is not a duration above zero, such as 1h or 7d"
+	)
+
+	label64 := strings.Repeat("a", 64) + ".example"
+	tooLong := strings.Repeat("a", 63) + "." + strings.Repeat("b", 63) + "." +
+		strings.Repeat("c", 62)
+
+	for _, tc := range []struct{ name, value, want string }{
+		{dnsblZones, "dnsbl..example", `"dnsbl..example"` + notZone},
+		{dnsblZones, "dnsbl.example.", `"dnsbl.example."` + notZone},
+		{dnsblZones, "-dnsbl.example", `"-dnsbl.example"` + notZone},
+		{dnsblZones, "dnsbl-.example", `"dnsbl-.example"` + notZone},
+		{dnsblZones, "dns_bl.example", `"dns_bl.example"` + notZone},
+		{dnsblZones, label64, `"` + label64 + `"` + notZone},
+		{
+			dnsblZones, tooLong,
+			`"` + tooLong + `" is longer than 189 characters, too long for the names ` +
+				`IPv6 clients are asked about by`,
+		},
+		{
+			dnsblZones, dronebl + "," + spamhaus + "," + dronebl,
+			`"` + dronebl + `" is listed twice`,
+		},
+		// DNS names ignore case.
+		{dnsblZones, "dnsbl.example,DNSBL.example", `"DNSBL.example" is listed twice`},
+		{dnsblResolver, "resolver.example", `"resolver.example"` + notResolver},
+		{dnsblResolver, "192.0.2.53:0", `"192.0.2.53:0"` + notResolver},
+		{dnsblResolver, "192.0.2.53:65536", `"192.0.2.53:65536"` + notResolver},
+		{dnsblResolver, "[2001:db8::53]", `"[2001:db8::53]"` + notResolver},
+		{
+			reputationAction, "ban",
+			`"ban" is not deny, limit:<percent> such as limit:25, or log`,
+		},
+		{reputationCacheTTL, off, `"off"` + notAboveZero},
+		{reputationTimeout, "0s", `"0s"` + notAboveZero},
+	} {
+		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+
+			want := tc.name + ": " + tc.want
+			if err == nil || err.Error() != want {
+				t.Errorf("error %v, want %s", err, want)
+			}
+		})
+	}
+}
+
+func TestMaskZoneKeyMasksTheFirstLabelOfAZoneUnderDqSpamhausNet(t *testing.T) {
+	t.Parallel()
+
+	for zone, want := range map[string]string{
+		spamhaus:                  spamhausMasked,
+		spamhaus + ".":            spamhausMasked + ".",
+		"KEY.ZEN.DQ.SPAMHAUS.NET": "********.ZEN.DQ.SPAMHAUS.NET",
+		dronebl:                   dronebl,
+		"dq.spamhaus.net":         "dq.spamhaus.net",
+		spamhaus + ".example":     spamhaus + ".example",
+	} {
+		if got := config.MaskZoneKey(zone); got != want {
+			t.Errorf("MaskZoneKey(%q) is %q, want %q", zone, got, want)
+		}
+	}
+}
+
+func TestDNSBLZoneKeyIsLoggedMaskedAndNeverShown(t *testing.T) {
+	t.Parallel()
+
+	cfg := fromEnvironment(t, environment{dnsblZones: dronebl + ", " + spamhaus})
+
+	var out bytes.Buffer
+
+	slog.New(slog.NewJSONHandler(&out, nil)).Info("starting", "settings", cfg)
+
+	logged := out.String()
+	if strings.Contains(logged, spamhausKey) ||
+		!strings.Contains(logged, `"`+dnsblZones+`":"`+dronebl+","+spamhausMasked+`"`) {
+		t.Errorf("the zones are not logged with the key masked: %s", logged)
+	}
+
+	// Nor does an error that stops the start show a key, in any case.
+	const (
+		notZone   = " is not a DNS zone such as dnsbl.dronebl.org"
+		otherKey  = "zyxwvutsrqponmlkjihgfedcba"
+		otherZone = otherKey + ".xbl.dq.spamhaus.net"
+	)
+
+	// 205 characters, 187 with the key masked.
+	labels := strings.Repeat("a", 63) + "." + strings.Repeat("b", 63) + "." +
+		strings.Repeat("c", 30) + ".xbl.dq.spamhaus.net"
+
+	for _, tc := range []struct{ value, want string }{
+		{spamhaus + ".", `"` + spamhausMasked + `."` + notZone},
+		{spamhausKey + "_.xbl.dq.spamhaus.net", `"` + spamhausMasked + `"` + notZone},
+		{
+			spamhausKey + "." + labels,
+			`"********.` + labels + `" is longer than 189 characters, too long ` +
+				`for the names IPv6 clients are asked about by`,
+		},
+		{
+			spamhaus + "," + strings.ToUpper(spamhaus),
+			`"********.XBL.DQ.SPAMHAUS.NET" is listed twice`,
+		},
+		{spamhaus + "," + otherZone, `"` + spamhausMasked + `" is listed twice`},
+		{spamhaus + ",,", "has an empty item in its list"},
+	} {
+		_, err := config.FromEnvironment(environment{dnsblZones: tc.value}.lookupEnv)
+
+		want := dnsblZones + ": " + tc.want
+		if err == nil || err.Error() != want {
+			t.Errorf("%s=%s gave the error %v, want %s", dnsblZones, tc.value, err, want)
+		}
+	}
+}
+
+func TestAbuseIPDBSettingsAsSet(t *testing.T) {
+	t.Parallel()
+
+	cfg := fromEnvironment(t, environment{})
+	if cfg.AbuseIPDBKey != "" || cfg.AbuseIPDBMinScore != 75 ||
+		cfg.AbuseIPDBDailyBudget != 900 {
+		t.Errorf("by default, the key %q, the minimum score %d and the daily budget %d, "+
+			"want none, 75 and 900", cfg.AbuseIPDBKey, cfg.AbuseIPDBMinScore,
+			cfg.AbuseIPDBDailyBudget)
+	}
+
+	cfg = fromEnvironment(t, environment{
+		abuseIPDBKey: token, abuseIPDBMinScore: "0", abuseIPDBDailyBudget: "1",
+	})
+	if cfg.AbuseIPDBKey != token || cfg.AbuseIPDBMinScore != 0 ||
+		cfg.AbuseIPDBDailyBudget != 1 {
+		t.Errorf("set, the key %q, the minimum score %d and the daily budget %d, "+
+			"want %s, 0 and 1", cfg.AbuseIPDBKey, cfg.AbuseIPDBMinScore,
+			cfg.AbuseIPDBDailyBudget, token)
+	}
+}
+
+func TestInvalidAbuseIPDBSettingStopsTheStartSayingWhatIsWrong(t *testing.T) {
+	t.Parallel()
+
+	const (
+		notScore  = " is not a percentage, a whole number from 0 to 100"
+		notBudget = " is not a whole number above zero, such as 5000"
+	)
+
+	for _, tc := range []struct{ name, value, want string }{
+		{abuseIPDBMinScore, "101", `"101"` + notScore},
+		{abuseIPDBMinScore, off, `"off"` + notScore},
+		{abuseIPDBDailyBudget, "0", `"0"` + notBudget},
+		{abuseIPDBDailyBudget, off, `"off"` + notBudget},
+		// The key itself is never shown.
+		{
+			abuseIPDBKey, token + "\r",
+			"holds a control character, such as the carriage return of a Windows line end",
+		},
+	} {
+		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+
+			want := tc.name + ": " + tc.want
+			if err == nil || err.Error() != want {
+				t.Errorf("error %v, want %s", err, want)
+			}
+		})
+	}
+}
+
+func TestAbuseIPDBKeyIsLoggedMasked(t *testing.T) {
+	t.Parallel()
+
+	cfg := fromEnvironment(t, environment{abuseIPDBKey: token})
+
+	var out bytes.Buffer
+
+	slog.New(slog.NewJSONHandler(&out, nil)).Info("starting", "settings", cfg)
+
+	logged := out.String()
+	if strings.Contains(logged, token) ||
+		!strings.Contains(logged, `"`+abuseIPDBKey+`":"********"`) {
+		t.Errorf("the key is not logged masked: %s", logged)
+	}
 }
 
 func TestSizesAndOff(t *testing.T) {
@@ -996,6 +1720,9 @@ func TestInvalidValueStopsTheStart(t *testing.T) {
 		{rateLimitPerHour, "1.5"},
 		{rateLimitPerDay, "-1"}, {rateLimitPerDay, "lots"},
 		{rateLimitExemptPaths, "/assets/,,/static/"},
+		{bytesLimitPerMinute, "10GB"}, {bytesLimitPerHour, "0"},
+		{bytesLimitPerDay, "-1G"},
+		{bytesCount, "all"}, {bytesCount, "Both"}, {bytesCount, ""},
 		{lookupSource, "ipinfo"}, {lookupSource, "GeoJS"}, {lookupSource, ""},
 		{lookupTimeout, off}, {lookupTimeout, "0s"}, {lookupTimeout, "1"},
 		{addLookupHeaders, "yes"},
@@ -1011,6 +1738,14 @@ func TestInvalidValueStopsTheStart(t *testing.T) {
 		{allowedCountries, "uk"},
 		{allowedCountries, "zz"},
 		{allowedCountries, "de,germany"},
+		{asnLimitPercent, "AS14061:50,,AS16276:50"}, {asnLimitPercent, "ASX:50"},
+		{asnLimitPercent, "AS14061:"}, {asnLimitPercent, "AS14061 :50"},
+		{asnLimitPercent, "AS14061:1.5"}, {asnLimitPercent, "AS-1:50"},
+		{countryLimitPercent, "cn"}, {countryLimitPercent, "cn:"},
+		{countryLimitPercent, "cn:25:50"}, {countryLimitPercent, "china:25"},
+		{asnBytesPercent, "AS14061:101"}, {countryBytesPercent, "su:50"},
+		{unknownLimitPercent, ""}, {unknownLimitPercent, "-1"},
+		{unknownLimitPercent, "50%"},
 		{metricsTopN, off}, {metricsTopN, "0"}, {metricsTopN, "-1"},
 		{logRequestHeaders, "accept,,origin"}, {logRequestHeaders, "accept;origin"},
 		{logRequestHeaders, "accept language"}, {logRequestHeaders, "x-foo:"},
@@ -1246,24 +1981,11 @@ func writeFile(t *testing.T, contents string) string {
 	return path
 }
 
+//nolint:funlen // one line for each setting, a list that grows with them
 func TestLogsEachSettingWithItsValue(t *testing.T) {
 	t.Parallel()
 
 	cfg := fromEnvironment(t, environment{clientRequestTimeout: "45s"})
-
-	var out bytes.Buffer
-
-	slog.New(slog.NewJSONHandler(&out, nil)).Info("starting", "settings", cfg)
-
-	var line struct {
-		Settings map[string]string `json:"settings"`
-	}
-
-	err := json.Unmarshal(out.Bytes(), &line)
-	if err != nil {
-		t.Fatalf("decode %s: %v", out.Bytes(), err)
-	}
-
 	hostname, _ := os.Hostname()
 
 	want := map[string]string{
@@ -1286,12 +2008,33 @@ func TestLogsEachSettingWithItsValue(t *testing.T) {
 		rateLimitPerHour:        "10000",
 		rateLimitPerDay:         "50000",
 		rateLimitExemptPaths:    "",
+		bytesLimitPerMinute:     "10G",
+		bytesLimitPerHour:       "20G",
+		bytesLimitPerDay:        "50G",
+		bytesCount:              "both",
 		lookupSource:            defaultLookupSource,
 		lookupDBPath:            "",
 		lookupTimeout:           "1s",
 		addLookupHeaders:        "false",
 		deniedCountries:         "",
 		allowedCountries:        "",
+		asnLimitPercent:         "",
+		countryLimitPercent:     "",
+		asnBytesPercent:         "",
+		countryBytesPercent:     "",
+		unknownLimitPercent:     "100",
+		asnLimitPercentURL:      "",
+		blocklistURLs:           "",
+		blocklistRefresh:        "24h",
+		blocklistAction:         actionDeny,
+		dnsblZones:              "",
+		dnsblResolver:           "",
+		abuseIPDBKey:            "",
+		abuseIPDBMinScore:       "75",
+		abuseIPDBDailyBudget:    "900",
+		reputationAction:        "limit:25",
+		reputationCacheTTL:      defaultReputationCacheTTL,
+		reputationTimeout:       "2s",
 		banResponse:             "403",
 		limitBanDuration:        "1h",
 		limitBanRepeatWindow:    "24h",
@@ -1323,11 +2066,33 @@ func TestLogsEachSettingWithItsValue(t *testing.T) {
 		alertCooldown:           defaultAlertCooldown,
 		alertMaxPerHour:         "60",
 	}
-	if !maps.Equal(line.Settings, want) {
-		t.Errorf("logged settings\n%v\nwant\n%v", line.Settings, want)
+	maps.Copy(want, loggedAnomalyDefaults())
+
+	if got := loggedSettings(t, cfg); !maps.Equal(got, want) {
+		t.Errorf("logged settings\n%v\nwant\n%v", got, want)
 	}
 }
 
+// loggedSettings returns the settings as cfg logs them, each by its name.
+func loggedSettings(t *testing.T, cfg *config.Config) map[string]string {
+	t.Helper()
+
+	var out bytes.Buffer
+
+	slog.New(slog.NewJSONHandler(&out, nil)).Info("starting", "settings", cfg)
+
+	var line struct {
+		Settings map[string]string `json:"settings"`
+	}
+
+	err := json.Unmarshal(out.Bytes(), &line)
+	if err != nil {
+		t.Fatalf("decode %s: %v", out.Bytes(), err)
+	}
+
+	return line.Settings
+}
+
 // wantSettings checks the settings that are plain values.
 func wantSettings(t *testing.T, got *config.Config, want config.Config) {
 	t.Helper()
@@ -1351,6 +2116,21 @@ func wantSettings(t *testing.T, got *config.Config, want config.Config) {
 	wantBanSettings(t, got, want)
 }
 
+// wantByteLimitSettings checks the settings for the byte limits.
+func wantByteLimitSettings(t *testing.T, got *config.Config, want config.Config) {
+	t.Helper()
+
+	if got.BytesLimitPerMinute != want.BytesLimitPerMinute ||
+		got.BytesLimitPerHour != want.BytesLimitPerHour ||
+		got.BytesLimitPerDay != want.BytesLimitPerDay ||
+		got.BytesCount != want.BytesCount {
+		t.Errorf("byte limits %d, %d and %d counting %s, want %d, %d and %d counting %s",
+			got.BytesLimitPerMinute, got.BytesLimitPerHour, got.BytesLimitPerDay,
+			got.BytesCount, want.BytesLimitPerMinute, want.BytesLimitPerHour,
+			want.BytesLimitPerDay, want.BytesCount)
+	}
+}
+
 // wantLookupSettings checks the settings for lookups.
 func wantLookupSettings(t *testing.T, got *config.Config, want config.Config) {
 	t.Helper()

internal/metrics/metrics.go

@@ -6,6 +6,7 @@ package metrics
 import (
 	"net/http"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
@@ -13,8 +14,10 @@ import (
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
 	"sneak.berlin/go/smallwebwaf/internal/bans"
+	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
 	"sneak.berlin/go/smallwebwaf/internal/remotelog"
+	"sneak.berlin/go/smallwebwaf/internal/reputation"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
 	"sneak.berlin/go/smallwebwaf/internal/rules"
 )
@@ -34,10 +37,12 @@ type Metrics struct {
 	rateLimitHits        *prometheus.CounterVec
 	sizeAndTimeLimitHits *prometheus.CounterVec
 	offences             *prometheus.CounterVec
-	// ruleMatches are made by AddRules.
-	ruleMatches *prometheus.CounterVec
-	countries   *busiest
-	asns        *busiest
+	// ruleMatches are made by AddRules, and reputationHits by
+	// AddReputation.
+	ruleMatches    *prometheus.CounterVec
+	reputationHits *prometheus.CounterVec
+	countries      *busiest
+	asns           *busiest
 
 	// GeoJSRequests are the requests to GeoJS, and GeoJSFailures those
 	// that failed. GeoJSUnanswered are the requests that needed their
@@ -89,8 +94,9 @@ func New(topN int, instanceName string) *Metrics {
 			Help: "How long requests passed to the app took, from then to their end.",
 		}),
 		rateLimitHits: counterVec("smallwebwaf_rate_limit_hits_total",
-			"Requests that broke a rate limit, by its window.",
-			[]string{"window"}),
+			"Requests that broke a rate limit or a byte limit, by its window and "+
+				"its kind, requests or bytes.",
+			[]string{"window", "kind"}),
 		sizeAndTimeLimitHits: counterVec("smallwebwaf_size_and_time_limit_hits_total",
 			"Requests that passed a size or time limit, by its setting.",
 			[]string{"limit"}),
@@ -251,6 +257,80 @@ func (m *Metrics) AddLookupFile(lastRead func() time.Time, readFailures func() i
 	)
 }
 
+// sourceLabel is the label of the reputation metrics: a list's URL, a
+// DNSBL zone, its key masked, or abuseipdb.
+const sourceLabel = "source"
+
+// AddReputation adds the metrics of the lists fetched from URLs and of the
+// DNSBL zones, by source, each list's URL or each zone, its key masked as
+// config.MaskZoneKey masks it: the requests whose client a blocklist, a
+// zone's verdict or AbuseIPDB's score lists, which ReputationHit counts,
+// and, read from lists and dnsbl as the metrics are asked for, for a list,
+// the fetches that failed and when the copy in use was fetched, and for a
+// zone, the queries made and those that failed. It is called once, before
+// ReputationHit.
+func (m *Metrics) AddReputation(lists *reputation.Lists, dnsbl *reputation.DNSBL) {
+	m.reputationHits = counterVec("smallwebwaf_reputation_hits_total",
+		"Requests whose client a blocklist, a DNSBL zone or AbuseIPDB lists, by "+
+			"the blocklist's URL, the zone, or abuseipdb.",
+		[]string{sourceLabel})
+	m.registry.MustRegister(m.reputationHits)
+
+	for _, zone := range dnsbl.Zones() {
+		source := prometheus.Labels{sourceLabel: config.MaskZoneKey(zone)}
+
+		m.addReputationQueries(source, func() int { return dnsbl.Queries(zone) })
+		m.addReputationFailures(source, func() int { return dnsbl.Failures(zone) })
+	}
+
+	for _, listURL := range lists.URLs() {
+		source := prometheus.Labels{sourceLabel: listURL}
+
+		m.addReputationFailures(source, func() int { return lists.Failures(listURL) })
+		m.registry.MustRegister(
+			prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+				Name: "smallwebwaf_reputation_last_fetch_timestamp_seconds",
+				Help: "When the copy of the list in use was fetched, in seconds since " +
+					"1970, or 0 while there is none.",
+				ConstLabels: source,
+			}, func() float64 {
+				fetched := lists.Fetched(listURL)
+				if fetched.IsZero() {
+					return 0
+				}
+
+				return float64(fetched.Unix())
+			}),
+		)
+	}
+}
+
+// AddAbuseIPDB adds the metrics of AbuseIPDB, with the source abuseipdb,
+// read from abuseIPDB as the metrics are asked for: the checks made, those
+// that failed, and how many checks the day's budget has left. It is
+// called once, after AddReputation, while SWWAF_ABUSEIPDB_KEY is set.
+func (m *Metrics) AddAbuseIPDB(abuseIPDB *reputation.AbuseIPDB) {
+	source := prometheus.Labels{sourceLabel: reputation.AbuseIPDBSource}
+
+	m.addReputationQueries(source, abuseIPDB.Checked)
+	m.addReputationFailures(source, abuseIPDB.Failures)
+	m.registry.MustRegister(
+		prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+			Name:        "smallwebwaf_reputation_daily_budget_remaining",
+			Help:        "Checks of the day's SWWAF_ABUSEIPDB_DAILY_BUDGET not yet spent.",
+			ConstLabels: source,
+		}, func() float64 {
+			return float64(abuseIPDB.BudgetLeft())
+		}),
+	)
+}
+
+// ReputationHit counts a request whose client source lists: a blocklist,
+// by its URL, a DNSBL zone, its key masked, or AbuseIPDB, abuseipdb.
+func (m *Metrics) ReputationHit(source string) {
+	m.reputationHits.WithLabelValues(source).Inc()
+}
+
 // AddAlerts adds the metrics of the alerts sent to each destination set,
 // read from queue as the metrics are asked for, by destination: the
 // alerts sent, the requests to the destination that failed, the alerts
@@ -325,7 +405,15 @@ func (m *Metrics) RequestEnded(
 	}
 
 	if line.LimitHit != "" {
-		m.rateLimitHits.WithLabelValues(line.LimitHit).Inc()
+		// The log line names a byte limit's window with _bytes after it.
+		window, isBytes := strings.CutSuffix(line.LimitHit, "_bytes")
+
+		kind := ratelimit.KindRequests
+		if isBytes {
+			kind = ratelimit.KindBytes
+		}
+
+		m.rateLimitHits.WithLabelValues(window, kind).Inc()
 	}
 
 	if limit != "" {
@@ -382,6 +470,32 @@ func (m *Metrics) StateFileEditSetAside(name string) {
 	m.stateFileEditsSetAside.WithLabelValues(name).Inc()
 }
 
+// addReputationQueries adds the counter of the queries to source, a DNSBL
+// zone, or of the checks of clients with AbuseIPDB, which count tells.
+func (m *Metrics) addReputationQueries(source prometheus.Labels, count func() int) {
+	m.registry.MustRegister(prometheus.NewCounterFunc(prometheus.CounterOpts{
+		Name:        "smallwebwaf_reputation_queries_total",
+		Help:        "Queries to the DNSBL zone, or checks of clients with AbuseIPDB.",
+		ConstLabels: source,
+	}, func() float64 {
+		return float64(count())
+	}))
+}
+
+// addReputationFailures adds the counter of the fetches of source, a
+// list, the queries to it, a DNSBL zone, or the checks with it, AbuseIPDB,
+// that failed, which count tells.
+func (m *Metrics) addReputationFailures(source prometheus.Labels, count func() int) {
+	m.registry.MustRegister(prometheus.NewCounterFunc(prometheus.CounterOpts{
+		Name: "smallwebwaf_reputation_failures_total",
+		Help: "Fetches of the list, queries to the DNSBL zone, or checks with " +
+			"AbuseIPDB, that failed.",
+		ConstLabels: source,
+	}, func() float64 {
+		return float64(count())
+	}))
+}
+
 // statusClass returns the class of status, such as 2xx, or none when no
 // status was sent.
 func statusClass(status int) string {

internal/proxy/alerts_test.go

@@ -203,7 +203,16 @@ func startWithAlerts(
 ) (*sender, *clock, *proxy.Server, *alerts.Queue) {
 	t.Helper()
 
-	app := startApp(t, func(http.ResponseWriter, *http.Request) {})
+	return startAppWithAlerts(t, func(http.ResponseWriter, *http.Request) {}, env)
+}
+
+// startAppWithAlerts is startWithAlerts in front of the app handler.
+func startAppWithAlerts(
+	t *testing.T, handler http.HandlerFunc, env map[string]string,
+) (*sender, *clock, *proxy.Server, *alerts.Queue) {
+	t.Helper()
+
+	app := startApp(t, handler)
 	clk := &clock{now: time.Date(2026, 10, 6, 0, 0, 0, 0, time.UTC)}
 	settings := map[string]string{
 		trustedProxies:  trustLocalhost,

internal/proxy/anomaly_internal_test.go

@@ -0,0 +1,30 @@
+package proxy
+
+import (
+	"net/netip"
+	"testing"
+
+	"sneak.berlin/go/smallwebwaf/internal/config"
+)
+
+func TestWithEveryAnomalyThresholdOffARequestIsNotCounted(t *testing.T) {
+	t.Parallel()
+
+	// A request from a client looked up through GeoJS, with every anomaly
+	// threshold off. Its handler has neither GeoJS's answers nor the
+	// anomaly counters, nor a clock, and the request no response: reading
+	// any of them to count the request panics.
+	rq := &request{
+		h:        &handler{config: &config.Config{LookupSource: "geojs"}},
+		client:   netip.MustParseAddr("203.0.113.9"),
+		lookedUp: true,
+	}
+
+	defer func() {
+		if r := recover(); r != nil {
+			t.Errorf("counting the request did work, with every threshold off: %v", r)
+		}
+	}()
+
+	rq.countAnomalies()
+}

internal/proxy/anomaly_test.go

@@ -0,0 +1,377 @@
+package proxy_test
+
+import (
+	"maps"
+	"net/http"
+	"net/netip"
+	"reflect"
+	"slices"
+	"strconv"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/anomaly"
+	"sneak.berlin/go/smallwebwaf/internal/proxy"
+	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
+	"sneak.berlin/go/smallwebwaf/internal/requestlog"
+)
+
+// The anomaly thresholds: the prefix of a scope followed by the end of a
+// count.
+const (
+	anomalyClient = "SWWAF_ANOMALY_CLIENT_"
+	anomalyNet    = "SWWAF_ANOMALY_NET_"
+	anomalyASN    = "SWWAF_ANOMALY_ASN_"
+	anomalyTotal  = "SWWAF_ANOMALY_TOTAL_"
+	anomalyWatch  = "SWWAF_WATCH_"
+
+	requestsPerMinute = "REQUESTS_PER_MINUTE"
+	requestsPerHour   = "REQUESTS_PER_HOUR"
+	bytesPerMinute    = "BYTES_PER_MINUTE"
+	bytesPerHour      = "BYTES_PER_HOUR"
+)
+
+// The other anomaly settings.
+const (
+	anomalyNetV4Prefix = "SWWAF_ANOMALY_NET_V4_PREFIX"
+	anomalyNetV6Prefix = "SWWAF_ANOMALY_NET_V6_PREFIX"
+	watchNets          = "SWWAF_WATCH_NETS"
+)
+
+const (
+	// clientsNet is the netblock around client at the default length, and
+	// office a named netblock of the same.
+	clientsNet = "203.0.113.0/24"
+	office     = "office=" + clientsNet
+	// aLot is a threshold no test reaches.
+	aLot = "1000"
+	// hour is the window an alert names for a threshold per hour.
+	hour = "hour"
+)
+
+func TestEachScopeAndWindowOverItsThresholdAlertsOncePerCooldown(t *testing.T) {
+	t.Parallel()
+
+	for _, scope := range []struct {
+		prefix, scope string
+		// netblock is the alert's, and counted what its reason names. extra
+		// is what its detail gives besides what every anomaly alert's does.
+		netblock netip.Prefix
+		counted  string
+		extra    map[string]any
+	}{
+		{
+			anomalyClient, anomaly.ScopeClient, netip.MustParsePrefix(client + "/32"),
+			"the client " + client + "/32", nil,
+		},
+		{
+			anomalyNet, anomaly.ScopeNet, netip.MustParsePrefix(clientsNet),
+			"the netblock " + clientsNet, nil,
+		},
+		{anomalyASN, anomaly.ScopeASN, netip.Prefix{}, asnDE, map[string]any{"asn": asnDE}},
+		{anomalyTotal, anomaly.ScopeTotal, netip.Prefix{}, "the whole service", nil},
+		{
+			anomalyWatch, anomaly.ScopeWatch, netip.MustParsePrefix(clientsNet),
+			"the named netblock office, " + clientsNet, map[string]any{"name": "office"},
+		},
+	} {
+		for _, threshold := range []struct {
+			end, kind, window string
+			// value is the threshold, which the third upload of 100 bytes
+			// takes the count over, to count.
+			value int64
+			count float64
+		}{
+			{requestsPerMinute, ratelimit.KindRequests, minute, 2, 3},
+			{requestsPerHour, ratelimit.KindRequests, hour, 2, 3},
+			{bytesPerMinute, ratelimit.KindBytes, minute, 250, 300},
+			{bytesPerHour, ratelimit.KindBytes, hour, 250, 300},
+		} {
+			setting := scope.prefix + threshold.end
+			value := strconv.FormatInt(threshold.value, 10)
+
+			t.Run(setting, func(t *testing.T) {
+				t.Parallel()
+
+				s, clk, server, queue := startWithLookupsAndClock(t, map[string]string{
+					setting: value, watchNets: office,
+				})
+				start := clk.Now()
+
+				// The third upload takes the count over the threshold, and the
+				// fourth, within the cooldown, is held back. Each is passed to
+				// the app.
+				for range 4 {
+					s.uploadFrom(client)
+				}
+
+				detail := map[string]any{
+					"scope": scope.scope, "window": threshold.window, "kind": threshold.kind,
+					"count": threshold.count, "threshold": threshold.value,
+				}
+				maps.Copy(detail, scope.extra)
+
+				wantAlerts(t, queue, alerts.Alert{
+					Instance: alertInstance,
+					Time:     start,
+					Event:    alerts.EventAnomaly,
+					Client:   netip.MustParseAddr(client),
+					Netblock: scope.netblock,
+					ASN:      asnDE,
+					ASName:   asNameDE,
+					Country:  "DE",
+					Reason: threshold.kind + " per " + threshold.window + " of " +
+						scope.counted + " over the threshold of " + value,
+					Detail: detail,
+				})
+
+				wantAlertedAgainOnceTheCooldownHasRunOut(t, s, clk, queue)
+
+				if held := server.Ledger.Snapshot(); len(held) != 0 {
+					t.Errorf("the ledger holds %+v, want no ban", held)
+				}
+			})
+		}
+	}
+}
+
+// wantAlertedAgainOnceTheCooldownHasRunOut checks that, once the cooldown
+// has run out after a first alert, which held back one repeat, the next
+// count over the threshold, at the latest three uploads from client on,
+// raises another alert, giving that repeat.
+func wantAlertedAgainOnceTheCooldownHasRunOut(
+	t *testing.T, s *sender, clk *clock, queue *alerts.Queue,
+) {
+	t.Helper()
+
+	clk.advance(15 * time.Minute)
+
+	for range 3 {
+		s.uploadFrom(client)
+	}
+
+	waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
+	if len(waiting) != 2 || !waiting[1].Time.Equal(clk.Now()) ||
+		waiting[1].SuppressedRepeats != 1 {
+		t.Errorf("alerts wait %+v, want the first and another, with 1 repeat", waiting)
+	}
+}
+
+func TestEveryRequestIsCountedWhateverIsDoneWithIt(t *testing.T) {
+	t.Parallel()
+
+	const (
+		allowed = "192.0.2.7"  // in SWWAF_ALLOW_NETS
+		exempt  = "192.0.2.10" // in SWWAF_RATE_LIMIT_EXEMPT_NETS
+		denied  = "192.0.2.20" // in SWWAF_DENY_NETS
+	)
+
+	s, _, _, queue := startAppWithAlerts(t, readAndAnswer, map[string]string{
+		anomalyClient + requestsPerMinute: "2",
+		allowNets:                         allowed,
+		rateLimitExemptNets:               exempt,
+		rateLimitExemptPaths:              "/static/",
+		denyNets:                          denied,
+	})
+
+	// The third request of each takes its client's count over the threshold
+	// of 2.
+	for _, sent := range []struct {
+		from, path string
+		status     int
+		action     string
+	}{
+		{allowed, "/", http.StatusOK, requestlog.ActionForward},
+		{exempt, "/", http.StatusOK, requestlog.ActionForward},
+		{client, "/static/app.js", http.StatusOK, requestlog.ActionForward},
+		{denied, "/", http.StatusForbidden, requestlog.ActionDenied},
+	} {
+		for range 3 {
+			s.request(sent.from, sent.path, sent.status, sent.action)
+		}
+	}
+
+	waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
+
+	got := make([]string, 0, len(waiting))
+	for _, alert := range waiting {
+		got = append(got, alert.Client.String())
+	}
+
+	if want := []string{allowed, exempt, client, denied}; !slices.Equal(got, want) {
+		t.Errorf("alerts for the clients %v, want %v", got, want)
+	}
+}
+
+func TestThresholdsOffCountNothingAndAlertNothing(t *testing.T) {
+	t.Parallel()
+
+	// With every threshold off, nothing is counted.
+	s, server, queue := startWithLookups(t, map[string]string{watchNets: office})
+
+	for range 5 {
+		s.uploadFrom(client)
+	}
+
+	if counters := server.Anomalies.Snapshot(); len(counters) != 0 {
+		t.Errorf("counters %+v, want none", counters)
+	}
+
+	wantAlerts(t, queue)
+
+	// With one set, its count alone is counted, in its scope alone.
+	s, clk, server, queue := startWithLookupsAndClock(t, map[string]string{
+		anomalyNet + requestsPerMinute: aLot, watchNets: office,
+	})
+
+	for range 5 {
+		s.uploadFrom(client)
+	}
+
+	want := []anomaly.Counter{{
+		Scope:    anomaly.ScopeNet,
+		Netblock: netip.MustParsePrefix(clientsNet),
+		Minute:   ratelimit.Buckets{Start: clk.Now(), Current: 5},
+	}}
+	if got := server.Anomalies.Snapshot(); !reflect.DeepEqual(got, want) {
+		t.Errorf("counters\n%+v\nwant\n%+v", got, want)
+	}
+
+	wantAlerts(t, queue)
+}
+
+func TestNetblockAroundAClientIsAsLongAsTheSettingsSay(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name string
+		env  map[string]string
+		// Each client of sent sends one request, and want gives the
+		// netblocks they are counted in, each with its requests.
+		sent []string
+		want map[string]int64
+	}{
+		{
+			"by default", nil,
+			[]string{client, "203.0.113.200", "192.0.2.7", ipv6Client, "2001:db8:0:ffff::1"},
+			map[string]int64{clientsNet: 2, "192.0.2.0/24": 1, "2001:db8::/48": 2},
+		},
+		{
+			"as set", map[string]string{anomalyNetV4Prefix: "16", anomalyNetV6Prefix: "32"},
+			[]string{client, "203.0.200.1", ipv6Client, "2001:db8:ffff::1"},
+			map[string]int64{"203.0.0.0/16": 2, "2001:db8::/32": 2},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			env := map[string]string{anomalyNet + requestsPerMinute: aLot}
+			maps.Copy(env, tc.env)
+
+			s, _, server, _ := startAppWithAlerts(t, readAndAnswer, env)
+
+			for _, from := range tc.sent {
+				s.get(from, http.StatusOK, requestlog.ActionForward)
+			}
+
+			got := map[string]int64{}
+			for _, counter := range server.Anomalies.Snapshot() {
+				got[counter.Netblock.String()] = counter.Minute.Current
+			}
+
+			if !maps.Equal(got, tc.want) {
+				t.Errorf("requests by netblock %v, want %v", got, tc.want)
+			}
+		})
+	}
+}
+
+func TestClientIsCountedForItsASNumberOnceTheLookupGivesOne(t *testing.T) {
+	t.Parallel()
+
+	s, server, _ := startWithLookups(t, map[string]string{
+		anomalyASN + requestsPerMinute: aLot,
+	})
+
+	// The lookup database does not hold unplaced.
+	for _, from := range []string{fromDE, fromDE, fromKP, noCountry, unplaced} {
+		s.uploadFrom(from)
+	}
+
+	got := map[string]int64{}
+	for _, counter := range server.Anomalies.Snapshot() {
+		got[counter.ASN] = counter.Minute.Current
+	}
+
+	if want := map[string]int64{asnDE: 2, asnKP: 1, "AS64500": 1}; !maps.Equal(got, want) {
+		t.Errorf("requests by AS number %v, want %v", got, want)
+	}
+}
+
+func TestRequestCountsForTheASNumberGeoJSGivesBeforeItEnds(t *testing.T) {
+	t.Parallel()
+
+	// The stand-in for GeoJS answers only once released, which the app
+	// does as it answers the request, and then waits until the answer is
+	// kept.
+	geojsURL, _, release := startHeldGeoJS(t)
+
+	var server atomic.Pointer[proxy.Server]
+
+	app := startApp(t, func(http.ResponseWriter, *http.Request) {
+		release()
+		waitUntil(func() bool {
+			_, kept := server.Load().GeoJS.Kept(netip.MustParsePrefix(fromDE + "/32"))
+
+			return kept
+		})
+	})
+	clk := &clock{now: time.Date(2026, 10, 6, 0, 0, 0, 0, time.UTC)}
+	addr, out, started := startProxyWithClock(t, app.URL, geojsURL, clk.Now,
+		map[string]string{
+			trustedProxies:                 trustLocalhost,
+			lookupTimeout:                  "1h",
+			anomalyASN + requestsPerMinute: aLot,
+		})
+	server.Store(started)
+
+	// The request went on without the answer, and is counted for the AS
+	// number it gives.
+	s := &sender{t: t, addr: addr, out: out}
+	if line := s.get(fromDE, http.StatusOK, requestlog.ActionForward); line.ASN != "" {
+		t.Errorf("log line has AS number %q, want none: the request waited", line.ASN)
+	}
+
+	want := []anomaly.Counter{{
+		Scope: anomaly.ScopeASN, ASN: asnDE,
+		Minute: ratelimit.Buckets{Start: clk.Now(), Current: 1},
+	}}
+	if got := started.Anomalies.Snapshot(); !reflect.DeepEqual(got, want) {
+		t.Errorf("counters\n%+v\nwant\n%+v", got, want)
+	}
+}
+
+func TestEachNamedNetblockCountsTheClientsInIt(t *testing.T) {
+	t.Parallel()
+
+	s, _, server, _ := startAppWithAlerts(t, readAndAnswer, map[string]string{
+		anomalyWatch + requestsPerMinute: aLot,
+		watchNets:                        office + ",wide=203.0.0.0/16,other=198.51.100.0/25",
+	})
+
+	// client is in office and in wide.
+	for _, from := range []string{client, "203.0.200.1", "192.0.2.7"} {
+		s.get(from, http.StatusOK, requestlog.ActionForward)
+	}
+
+	got := map[string]int64{}
+	for _, counter := range server.Anomalies.Snapshot() {
+		got[counter.Name] = counter.Minute.Current
+	}
+
+	if want := map[string]int64{"office": 1, "wide": 2}; !maps.Equal(got, want) {
+		t.Errorf("requests by named netblock %v, want %v", got, want)
+	}
+}

internal/proxy/bans.go

@@ -6,6 +6,7 @@ import (
 
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
 	"sneak.berlin/go/smallwebwaf/internal/bans"
+	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
 	"sneak.berlin/go/smallwebwaf/internal/rules"
 )
@@ -41,57 +42,125 @@ func (rq *request) banned(now time.Time) bool {
 
 // limitBroken counts the request for the rate limits at now, notes the
 // client's counts for the log line, and reports whether the request takes
-// the client over a limit. In enforce mode such a request bans the
-// client's netblock, and sets the client's counters back to zero; in
-// observe mode it does neither, and raises the alert for the ban it would
-// have made, if that alert would be sent.
+// the client over a rate limit, as its limit percentage lowers it, which
+// breaks it.
 func (rq *request) limitBroken(now time.Time) bool {
-	group := clientGroup(rq.client)
-
-	counts, hit, over := rq.h.limiter.Count(group, now)
+	counts, hit, over := rq.h.limiter.Count(clientGroup(rq.client), now,
+		rq.limitPercent.percent)
 	rq.line.Counts = counts
 
-	if !over {
-		return false
+	if over {
+		rq.banForLimit(now, hit, rq.h.config.BanResponse)
 	}
 
+	return over
+}
+
+// countBytes counts the request's bytes, as countedBytes gives them, for
+// the byte limits, once its response has ended, and notes the client's
+// byte totals for the log line; its requests stay there as the rate limits
+// counted them. Only a request passed to the app has them counted, and
+// only one the rate limits counted; in observe mode, not one that enforce
+// mode would have refused. Bytes that take the client over a byte limit,
+// as its limit percentage for the byte limits lowers it, break it; the
+// response was passed on whole.
+func (rq *request) countBytes() {
+	if !rq.counted || rq.line.WouldAction != "" {
+		return
+	}
+
+	now := rq.h.now()
+
+	counts, hit, over := rq.h.limiter.CountBytes(clientGroup(rq.client), now,
+		rq.countedBytes(), rq.bytesPercent.percent)
+	rq.line.Counts.MinuteBytes = counts.MinuteBytes
+	rq.line.Counts.HourBytes = counts.HourBytes
+	rq.line.Counts.DayBytes = counts.DayBytes
+
+	if over {
+		rq.banForLimit(now, hit, rq.out.status)
+	}
+}
+
+// countedBytes returns the request's bytes, once it has ended, as the
+// byte limits and the anomaly thresholds count them: the response's body
+// bytes, the request's, or both, as SWWAF_BYTES_COUNT says. For an
+// upgraded connection, such as a WebSocket, which has closed by then, what
+// it carried from the app counts with the response's and what it carried
+// from the client with the request's.
+func (rq *request) countedBytes() int64 {
+	response, request := rq.out.bytes, rq.requestBytes()
+	if rq.upgraded != nil {
+		response += rq.upgraded.fromApp.Load()
+		request += rq.upgraded.toApp.Load()
+	}
+
+	switch rq.h.config.BytesCount {
+	case "response":
+		return response
+	case "request":
+		return request
+	default: // both
+		return response + request
+	}
+}
+
+// banForLimit bans the client's netblock at now for a broken limit, the
+// one hit names, and notes the offence for the log line. status is what
+// the client was sent, or is sent: SWWAF_BAN_RESPONSE for a request over
+// a rate limit, the app's answer for one whose bytes broke a byte limit.
+// The ban's notes give the client's limit percentage for that kind of
+// limit. The ban sets the client's counters back to zero. In observe mode
+// it makes no ban and sets nothing back, and raises the alert for the ban
+// it would have made, if that alert would be sent.
+func (rq *request) banForLimit(now time.Time, hit ratelimit.Hit, status int) {
 	rq.line.LimitHit = hit.Window
+	if hit.Kind == ratelimit.KindBytes {
+		rq.line.LimitHit += "_bytes" // as counts names the byte totals
+	}
+
 	rq.line.Offence = requestlog.OffenceLimit
 
 	netblock := rq.h.netblock(rq.client)
 	if rq.h.config.Observe && !rq.wouldAlertBan(netblock, now, bans.CauseLimit) {
-		return true
+		return
 	}
 
 	notes := bans.Notes{
 		ASN:      rq.line.ASN,
 		ASName:   rq.line.ASName,
 		Country:  rq.line.Country,
+		Kind:     hit.Kind,
 		Limit:    hit.Limit,
 		Window:   hit.Window,
-		Count:    hit.Requests,
-		Request:  rq.noted(now),
+		Count:    hit.Count,
+		Request:  rq.noted(now, status),
 		Requests: rq.netblockRequests(netblock),
 	}
 
+	percent := rq.limitPercent
+	if hit.Kind == ratelimit.KindBytes {
+		percent = rq.bytesPercent
+	}
+
+	notes.LimitPercent, notes.LimitPercentSetting = percent.logged()
+
 	if rq.h.config.Observe {
 		ban, wouldBan := rq.h.ledger.WouldBanForLimit(netblock, now, notes)
 		if wouldBan {
 			rq.alertBan(ban)
 		}
 
-		return true
+		return
 	}
 
 	ban, made := rq.h.ledger.BanForLimit(netblock, now, notes)
-	rq.h.limiter.Reset(group)
+	rq.h.limiter.Reset(clientGroup(rq.client))
 	rq.line.BanExpires = banExpires(ban)
 
 	if made {
 		rq.alertBan(ban)
 	}
-
-	return true
 }
 
 // banForAttack bans the client's netblock at now for a clear sign of
@@ -110,7 +179,7 @@ func (rq *request) banForAttack(now time.Time, rule rules.Rule) {
 		Country:  rq.line.Country,
 		RuleID:   rule.ID,
 		Target:   rule.Target,
-		Request:  rq.noted(now),
+		Request:  rq.noted(now, rq.h.config.BanResponse),
 		Requests: rq.netblockRequests(netblock),
 	}
 
@@ -177,16 +246,16 @@ func (rq *request) alertBan(ban bans.Ban) {
 	})
 }
 
-// noted is the request, refused at now with SWWAF_BAN_RESPONSE, or in
-// observe mode as it would have been, as the notes of the ban it makes
-// keep it.
-func (rq *request) noted(now time.Time) bans.Request {
+// noted is the request, at now, with status, what the client was sent, or
+// in observe mode would have been, as the notes of the ban it makes keep
+// it.
+func (rq *request) noted(now time.Time, status int) bans.Request {
 	return bans.Request{
 		Time:      now,
 		Method:    rq.in.Method,
 		Host:      rq.in.Host,
 		Path:      rq.in.URL.RequestURI(),
-		Status:    rq.h.config.BanResponse,
+		Status:    status,
 		UserAgent: rq.in.UserAgent(),
 	}
 }

internal/proxy/bans_test.go

@@ -284,6 +284,7 @@ func TestBanNotes(t *testing.T) {
 			ASN:     asnDE,
 			ASName:  asNameDE,
 			Country: "DE",
+			Kind:    "requests",
 			Limit:   1,
 			Window:  minute,
 			Count:   2,

internal/proxy/biased.go

@@ -0,0 +1,119 @@
+package proxy
+
+import (
+	"sneak.berlin/go/smallwebwaf/internal/config"
+)
+
+// whole is the percentage of each limit a client gets when no biased
+// threshold lowers its limits.
+const whole = 100
+
+// percentage is a client's limit percentage for the rate limits or for
+// the byte limits, as the biased thresholds give it, and the setting that
+// gave it: "" with whole when none lowers that kind of limit.
+type percentage struct {
+	percent int64
+	setting string
+}
+
+// biasedThresholdsSet reports whether a biased threshold can lower a
+// client's limits: one of its lists is not empty,
+// SWWAF_UNKNOWN_LIMIT_PERCENT is below 100, or SWWAF_ASN_LIMIT_PERCENT_URL
+// is set. The client's lookup is then needed before its request goes on.
+func biasedThresholdsSet(cfg *config.Config) bool {
+	return len(cfg.ASNLimitPercent) > 0 || len(cfg.CountryLimitPercent) > 0 ||
+		len(cfg.ASNBytesPercent) > 0 || len(cfg.CountryBytesPercent) > 0 ||
+		cfg.UnknownLimitPercent < whole || cfg.ASNLimitPercentURL != ""
+}
+
+// limitPercentages returns the client's limit percentages, for the rate
+// limits and for the byte limits, by its AS number and country as looked
+// up, each "" when unknown, and the blocklists, DNSBL zones and AbuseIPDB
+// that list it. Each is the lowest of those the settings give it, the
+// first of them in the order below when several are lowest: the
+// percentage SWWAF_ASN_LIMIT_PERCENT gives its AS number, the one the file
+// SWWAF_ASN_LIMIT_PERCENT_URL names gives it, the one
+// SWWAF_COUNTRY_LIMIT_PERCENT gives its country, for a client without a
+// country, SWWAF_UNKNOWN_LIMIT_PERCENT, for a client a blocklist lists,
+// the percentage of SWWAF_BLOCKLIST_ACTION while it is limit, and for a
+// client a DNSBL zone's verdict lists, or whose AbuseIPDB score is a hit,
+// the percentage of SWWAF_REPUTATION_ACTION while it is limit. For the
+// byte limits, SWWAF_ASN_BYTES_PERCENT and SWWAF_COUNTRY_BYTES_PERCENT
+// take the place of the first three for an AS number or a country they
+// list.
+func (rq *request) limitPercentages() (percentage, percentage) {
+	cfg := rq.h.config
+	asn, country := rq.line.ASN, rq.line.Country
+
+	unknown := percentage{percent: whole}
+	if country == "" {
+		unknown = percentage{cfg.UnknownLimitPercent, "SWWAF_UNKNOWN_LIMIT_PERCENT"}
+	}
+
+	fetched := percentage{percent: whole}
+	if percent, listed := rq.h.lists.ASNLimitPercent(asn); listed {
+		fetched = percentage{percent, "SWWAF_ASN_LIMIT_PERCENT_URL"}
+	}
+
+	blocklisted := percentage{percent: whole}
+	if rq.blocklisted && cfg.BlocklistAction == "limit" {
+		blocklisted = percentage{cfg.BlocklistLimitPercent, "SWWAF_BLOCKLIST_ACTION"}
+	}
+
+	reputationListed := percentage{percent: whole}
+	if (rq.dnsblListed || rq.abuseIPDBHit) && cfg.ReputationAction == "limit" {
+		reputationListed = percentage{cfg.ReputationLimitPercent, "SWWAF_REPUTATION_ACTION"}
+	}
+
+	asnRequests := lowest(given(cfg.ASNLimitPercent, asn, "SWWAF_ASN_LIMIT_PERCENT"),
+		fetched)
+	countryRequests := given(cfg.CountryLimitPercent, country,
+		"SWWAF_COUNTRY_LIMIT_PERCENT")
+
+	asnBytes, countryBytes := asnRequests, countryRequests
+	if _, listed := cfg.ASNBytesPercent[asn]; listed {
+		asnBytes = given(cfg.ASNBytesPercent, asn, "SWWAF_ASN_BYTES_PERCENT")
+	}
+
+	if _, listed := cfg.CountryBytesPercent[country]; listed {
+		countryBytes = given(cfg.CountryBytesPercent, country, "SWWAF_COUNTRY_BYTES_PERCENT")
+	}
+
+	return lowest(asnRequests, countryRequests, unknown, blocklisted, reputationListed),
+		lowest(asnBytes, countryBytes, unknown, blocklisted, reputationListed)
+}
+
+// given returns the percentage percents, the setting named setting, gives
+// code, an AS number or a country, or whole when it does not list code.
+func given(percents map[string]int64, code, setting string) percentage {
+	percent, listed := percents[code]
+	if !listed {
+		return percentage{percent: whole}
+	}
+
+	return percentage{percent, setting}
+}
+
+// lowest returns the lowest of percentages below whole, the first of them
+// when several are lowest, or whole when none is below it.
+func lowest(percentages ...percentage) percentage {
+	low := percentage{percent: whole}
+
+	for _, p := range percentages {
+		if p.percent < low.percent {
+			low = p
+		}
+	}
+
+	return low
+}
+
+// logged returns p as the log line and the notes of a ban give it: its
+// percent and setting, or nil and "" for whole, which they leave out.
+func (p percentage) logged() (*int64, string) {
+	if p.percent == whole {
+		return nil, ""
+	}
+
+	return &p.percent, p.setting
+}

internal/proxy/biased_test.go

@@ -0,0 +1,504 @@
+package proxy_test
+
+import (
+	"fmt"
+	"io"
+	"maps"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"net/netip"
+	"path/filepath"
+	"strings"
+	"testing"
+	"testing/synctest"
+	"time"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/bans"
+	"sneak.berlin/go/smallwebwaf/internal/lookup/lookuptest"
+	"sneak.berlin/go/smallwebwaf/internal/proxy"
+	"sneak.berlin/go/smallwebwaf/internal/requestlog"
+)
+
+// The biased thresholds.
+const (
+	asnLimitPercent     = "SWWAF_ASN_LIMIT_PERCENT"
+	countryLimitPercent = "SWWAF_COUNTRY_LIMIT_PERCENT"
+	asnBytesPercent     = "SWWAF_ASN_BYTES_PERCENT"
+	countryBytesPercent = "SWWAF_COUNTRY_BYTES_PERCENT"
+	unknownLimitPercent = "SWWAF_UNKNOWN_LIMIT_PERCENT"
+)
+
+const (
+	// asnDEHalf and countryDEHalf give fromDE's AS number and its country
+	// half of every limit, and asnDEQuarter gives its AS number a quarter.
+	asnDEHalf     = asnDE + ":50"
+	asnDEQuarter  = asnDE + ":25"
+	countryDEHalf = "de:50"
+	// noCountry is in an AS of its own, AS64500, and in no country.
+	noCountry = "192.0.2.80"
+	// fourAMinute is the rate limit these tests set: half of it is 2
+	// requests a minute, a quarter of it 1.
+	fourAMinute = "4"
+	// twoUploads is the byte limit these tests set: 199 bytes, which an
+	// upload, a request with a body and its answer, 100 bytes, is within,
+	// and half of which, 99 bytes, it is over.
+	twoUploads = "199"
+	// none is how percentText gives a percentage left out.
+	none = "none"
+)
+
+func TestEachBiasedThresholdLowersTheRateLimits(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		setting, value, from string
+	}{
+		{asnLimitPercent, asnDEHalf, fromDE},
+		{countryLimitPercent, countryDEHalf, fromDE},
+		{unknownLimitPercent, "50", unplaced},
+	} {
+		t.Run(tc.setting, func(t *testing.T) {
+			t.Parallel()
+
+			s, _, _ := startWithLookups(t, map[string]string{
+				rateLimitPerMinute: fourAMinute, tc.setting: tc.value,
+			})
+
+			// Half of 4 requests a minute: the third breaks the limit.
+			for _, sent := range []struct {
+				status int
+				action string
+			}{
+				{http.StatusOK, requestlog.ActionForward},
+				{http.StatusOK, requestlog.ActionForward},
+				{http.StatusForbidden, requestlog.ActionRateLimited},
+			} {
+				line := s.get(tc.from, sent.status, sent.action)
+				wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+					"50 from "+tc.setting)
+			}
+
+			// fromKP, which no setting lists, has the whole limit.
+			for range 3 {
+				line := s.get(fromKP, http.StatusOK, requestlog.ActionForward)
+				wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+					none)
+			}
+		})
+	}
+}
+
+func TestEachBiasedThresholdLowersTheByteLimits(t *testing.T) {
+	t.Parallel()
+
+	// The AS numbers and countries are given in either case.
+	for _, tc := range []struct {
+		setting, value, from string
+	}{
+		{asnLimitPercent, asnDEHalf, fromDE},
+		{countryLimitPercent, "DE:50", fromDE},
+		{unknownLimitPercent, "50", unplaced},
+		{asnBytesPercent, "as64496:50", fromDE},
+		{countryBytesPercent, countryDEHalf, fromDE},
+	} {
+		t.Run(tc.setting, func(t *testing.T) {
+			t.Parallel()
+
+			s, _, _ := startWithLookups(t, map[string]string{
+				bytesLimitPerMinute: twoUploads, tc.setting: tc.value,
+			})
+
+			// The upload's 100 bytes are over half of 199, 99.
+			line := s.uploadFrom(tc.from)
+			if line.LimitHit != minuteBytes {
+				t.Errorf("log line has limit_hit %q, want %s", line.LimitHit, minuteBytes)
+			}
+
+			wantPercent(t, "bytes_percent", line.BytesPercent, line.BytesPercentSetting,
+				"50 from "+tc.setting)
+
+			// fromKP, which no setting lists, has the whole limit.
+			line = s.uploadFrom(fromKP)
+			if line.LimitHit != "" {
+				t.Errorf("log line for %s has limit_hit %q, want none", fromKP, line.LimitHit)
+			}
+
+			wantPercent(t, "bytes_percent", line.BytesPercent, line.BytesPercentSetting, none)
+		})
+	}
+}
+
+func TestBytesPercentSettingsTakeThePlaceOfTheOthersForByteLimits(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name string
+		env  map[string]string
+		// limitPercent and bytesPercent are the log line's, as percentText
+		// gives them, and limitHit is its limit_hit.
+		limitPercent, bytesPercent, limitHit string
+	}{
+		{
+			"lowering the byte limits alone",
+			map[string]string{asnBytesPercent: asnDEHalf},
+			none, "50 from " + asnBytesPercent, minuteBytes,
+		},
+		{
+			"lowering the byte limits alone, by country",
+			map[string]string{countryBytesPercent: countryDEHalf},
+			none, "50 from " + countryBytesPercent, minuteBytes,
+		},
+		{
+			"raising the byte limits back",
+			map[string]string{asnLimitPercent: asnDEHalf, asnBytesPercent: asnDE + ":100"},
+			"50 from " + asnLimitPercent, none, "",
+		},
+		{
+			"raising the byte limits back, by country",
+			map[string]string{countryLimitPercent: countryDEHalf, countryBytesPercent: "de:100"},
+			"50 from " + countryLimitPercent, none, "",
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			env := map[string]string{bytesLimitPerMinute: twoUploads}
+			maps.Copy(env, tc.env)
+			s, _, _ := startWithLookups(t, env)
+
+			// The upload's 100 bytes are over 99, half of 199, and within 199.
+			line := s.uploadFrom(fromDE)
+			if line.LimitHit != tc.limitHit {
+				t.Errorf("log line has limit_hit %q, want %q", line.LimitHit, tc.limitHit)
+			}
+
+			wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+				tc.limitPercent)
+			wantPercent(t, "bytes_percent", line.BytesPercent, line.BytesPercentSetting,
+				tc.bytesPercent)
+		})
+	}
+}
+
+func TestZeroPercentIsAZeroAllowance(t *testing.T) {
+	t.Parallel()
+
+	s, _, _ := startWithLookups(t, map[string]string{asnLimitPercent: asnDE + ":0"})
+
+	// The first request breaks the limit, and bans the client; the log line
+	// gives the 0.
+	line := s.get(fromDE, http.StatusForbidden, requestlog.ActionRateLimited)
+	if line.fields["limit_percent"] != float64(0) ||
+		line.fields["limit_percent_setting"] != asnLimitPercent {
+		t.Errorf("log line has limit_percent %v from %v, want 0 from %s",
+			line.fields["limit_percent"], line.fields["limit_percent_setting"],
+			asnLimitPercent)
+	}
+
+	s.get(fromDE, http.StatusForbidden, requestlog.ActionBanned)
+}
+
+func TestLowestPercentageApplies(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name string
+		env  map[string]string
+		from string
+		// want is the log line's limit_percent, as percentText gives it.
+		want string
+	}{
+		{
+			"the country's",
+			map[string]string{asnLimitPercent: asnDEHalf, countryLimitPercent: "de:25"},
+			fromDE, "25 from " + countryLimitPercent,
+		},
+		{
+			"the AS number's",
+			map[string]string{asnLimitPercent: asnDEQuarter, countryLimitPercent: countryDEHalf},
+			fromDE, "25 from " + asnLimitPercent,
+		},
+		{
+			"the AS number's, the first of two alike",
+			map[string]string{asnLimitPercent: asnDEQuarter, countryLimitPercent: "de:25"},
+			fromDE, "25 from " + asnLimitPercent,
+		},
+		{
+			"that for a client without a country",
+			map[string]string{asnLimitPercent: "AS64500:50", unknownLimitPercent: "25"},
+			noCountry, "25 from " + unknownLimitPercent,
+		},
+		{
+			// SWWAF_UNKNOWN_LIMIT_PERCENT is left at its default, 100.
+			"the AS number's, for a client without a country",
+			map[string]string{asnLimitPercent: "AS64500:25"},
+			noCountry, "25 from " + asnLimitPercent,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			env := map[string]string{rateLimitPerMinute: fourAMinute}
+			maps.Copy(env, tc.env)
+			s, _, _ := startWithLookups(t, env)
+
+			// A quarter of 4 requests a minute: the second breaks the limit.
+			s.get(tc.from, http.StatusOK, requestlog.ActionForward)
+
+			line := s.get(tc.from, http.StatusForbidden, requestlog.ActionRateLimited)
+			wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+				tc.want)
+		})
+	}
+}
+
+func TestUnknownLimitPercentGivesEveryClientWithoutACountryItsPercentage(t *testing.T) {
+	t.Parallel()
+
+	s, _, _ := startWithLookups(t, map[string]string{
+		rateLimitPerMinute: fourAMinute, unknownLimitPercent: "50",
+	})
+
+	// One the lookup database does not hold, and one on a private address,
+	// which is never looked up: the third request of each breaks half of 4.
+	for _, from := range []string{unplaced, "10.0.0.8"} {
+		s.get(from, http.StatusOK, requestlog.ActionForward)
+		s.get(from, http.StatusOK, requestlog.ActionForward)
+		s.get(from, http.StatusForbidden, requestlog.ActionRateLimited)
+	}
+
+	// One in a country has the whole limit.
+	for range 3 {
+		s.get(fromDE, http.StatusOK, requestlog.ActionForward)
+	}
+}
+
+func TestClientWithoutAnAnswerInTimeHasTheUnknownLimitPercent(t *testing.T) {
+	t.Parallel()
+
+	// In a synctest bubble, as TestRequestWaitsAsLongAsTheLookupTimeoutSays
+	// says, with a GeoJS that never answers.
+	synctest.Test(t, func(t *testing.T) {
+		server, out, _ := newProxy(t, "http://app.invalid", unansweredGeoJSURL,
+			time.Now, map[string]string{unknownLimitPercent: "0"})
+
+		// Once the second the request waits for its answer is up, the client
+		// counts as without a country, and its zero allowance refuses the
+		// request before it reaches the app.
+		serveFromDE(t, server, http.MethodGet, http.NoBody)
+
+		line := out.requestLine(t)
+		wantLine(t, line, http.StatusForbidden, requestlog.ActionRateLimited)
+		wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+			"0 from "+unknownLimitPercent)
+	})
+}
+
+func TestRequestWaitsForItsLookupWhileABiasedThresholdIsSet(t *testing.T) {
+	t.Parallel()
+
+	const timeout = 3 * time.Second
+
+	for _, tc := range []struct {
+		setting, value string
+		waits          bool
+	}{
+		{asnLimitPercent, asnDEHalf, true},
+		{countryLimitPercent, countryDEHalf, true},
+		{asnBytesPercent, asnDEHalf, true},
+		{countryBytesPercent, countryDEHalf, true},
+		{unknownLimitPercent, "99", true},
+		{asnLimitPercentURL, asnURL, true},
+		// At 100, its default, it lowers no limit.
+		{unknownLimitPercent, "100", false},
+	} {
+		t.Run(tc.setting+"="+tc.value, func(t *testing.T) {
+			t.Parallel()
+
+			// In a synctest bubble, as TestRequestWaitsAsLongAsTheLookupTimeoutSays
+			// says, with a GeoJS that never answers.
+			synctest.Test(t, func(t *testing.T) {
+				// The request's body is over SWWAF_REQUEST_MAX_BYTES, so that it
+				// is refused after the checks, and never reaches the app.
+				server, out, _ := newProxy(t, "http://app.invalid", unansweredGeoJSURL,
+					time.Now, map[string]string{
+						lookupTimeout: timeout.String(), requestMaxBytes: "1",
+						tc.setting: tc.value,
+					})
+				began := time.Now()
+
+				serveFromDE(t, server, http.MethodPost, strings.NewReader("ab"))
+
+				want := time.Duration(0)
+				if tc.waits {
+					want = timeout
+				}
+
+				if waited := time.Since(began); waited != want {
+					t.Errorf("the request waited %s for its answer, want %s", waited, want)
+				}
+
+				wantLine(t, out.requestLine(t), http.StatusRequestEntityTooLarge,
+					requestlog.ActionTooLarge)
+
+				// The bubble's clock stops once this function returns, so the
+				// request to GeoJS, which a request that did not wait leaves
+				// under way, has to be abandoned before then.
+				time.Sleep(timeout)
+			})
+		})
+	}
+}
+
+func TestBanForALoweredLimitGivesThePercentageInItsNotesAndItsAlert(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name string
+		env  map[string]string
+		// before is how many uploads come before the one that breaks a
+		// limit, which is answered with status and logged with action.
+		before int
+		status int
+		action string
+		// reason and want are the ban's reason, and its notes' limit
+		// percentage, as percentText gives it.
+		reason, want string
+	}{
+		{
+			// A quarter of 12 requests a minute is 3: the fourth breaks it.
+			"a rate limit",
+			map[string]string{rateLimitPerMinute: "12", asnLimitPercent: asnDEQuarter},
+			3, http.StatusForbidden, requestlog.ActionRateLimited,
+			"requests per minute over the limit of 3", "25 from " + asnLimitPercent,
+		},
+		{
+			// The byte limits' percentage, not the rate limits'.
+			"a byte limit",
+			map[string]string{
+				bytesLimitPerMinute: twoUploads, asnLimitPercent: asnDEQuarter,
+				asnBytesPercent: asnDEHalf,
+			},
+			0, http.StatusOK, requestlog.ActionForward,
+			"bytes per minute over the limit of 99", "50 from " + asnBytesPercent,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			s, server, queue := startWithLookups(t, tc.env)
+
+			for range tc.before {
+				s.uploadFrom(fromDE)
+			}
+
+			s.requestWithBody(http.MethodPost, fromDE, "/", uploadHeader, uploadBody,
+				tc.status, tc.action)
+
+			held := server.Ledger.Bans(netip.MustParsePrefix(fromDE + "/32"))
+			if len(held) != 1 {
+				t.Fatalf("bans %+v, want one", held)
+			}
+
+			notes := held[0].Notes
+			if held[0].Reason != tc.reason {
+				t.Errorf("the ban's reason is %q, want %q", held[0].Reason, tc.reason)
+			}
+
+			wantPercent(t, "the notes' limit_percent", notes.LimitPercent,
+				notes.LimitPercentSetting, tc.want)
+
+			waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
+			if len(waiting) != 1 {
+				t.Fatalf("%d alerts wait, want the ban's alone: %+v", len(waiting), waiting)
+			}
+
+			alerted, _ := waiting[0].Detail["notes"].(bans.Notes)
+			wantPercent(t, "the alert's notes' limit_percent", alerted.LimitPercent,
+				alerted.LimitPercentSetting, tc.want)
+		})
+	}
+}
+
+// startWithLookups is startWithLookupsAndClock for a test that needs no
+// clock.
+func startWithLookups(
+	t *testing.T, env map[string]string,
+) (*sender, *proxy.Server, *alerts.Queue) {
+	t.Helper()
+
+	s, _, server, queue := startWithLookupsAndClock(t, env)
+
+	return s, server, queue
+}
+
+// startWithLookupsAndClock is startAppWithAlerts in front of
+// readAndAnswer, with the settings in env on top of clients looked up in a
+// lookup database, which places fromDE and fromKP in the AS numbers and
+// countries the stand-in for GeoJS gives them, noCountry in AS64500 and no
+// country, and no other address.
+func startWithLookupsAndClock(
+	t *testing.T, env map[string]string,
+) (*sender, *clock, *proxy.Server, *alerts.Queue) {
+	t.Helper()
+
+	path := filepath.Join(t.TempDir(), "ipinfo_lite.mmdb")
+	lookuptest.Write(t, path, map[string]lookuptest.Network{
+		fromDE + "/32":    {ASN: asnDE, ASName: asNameDE, Country: "DE"},
+		fromKP + "/32":    {ASN: asnKP, ASName: asNameKP, Country: "KP"},
+		noCountry + "/32": {ASN: "AS64500", ASName: "Nowhere Net"},
+	})
+
+	settings := map[string]string{lookupSource: fileSource, lookupDBPath: path}
+	maps.Copy(settings, env)
+
+	return startAppWithAlerts(t, readAndAnswer, settings)
+}
+
+// uploadFrom is upload from the client at from.
+func (s *sender) uploadFrom(from string) logLine {
+	s.t.Helper()
+
+	line, _ := s.requestWithBody(http.MethodPost, from, "/", uploadHeader, uploadBody,
+		http.StatusOK, requestlog.ActionForward)
+
+	return line
+}
+
+// serveFromDE hands a request from fromDE with method and body straight to
+// server's handler, without the network, and returns once it is answered.
+func serveFromDE(t *testing.T, server *proxy.Server, method string, body io.Reader) {
+	t.Helper()
+
+	req := httptest.NewRequestWithContext(t.Context(), method, "/", body)
+	req.RemoteAddr = net.JoinHostPort(fromDE, "1234")
+
+	server.Handler.ServeHTTP(httptest.NewRecorder(), req)
+}
+
+// wantPercent checks a limit percentage that a log line or a ban's notes
+// give, what, and the setting that gave it, against want, as percentText
+// gives them.
+func wantPercent(t *testing.T, what string, percent *int64, setting, want string) {
+	t.Helper()
+
+	if got := percentText(percent, setting); got != want {
+		t.Errorf("%s is %s, want %s", what, got, want)
+	}
+}
+
+// percentText gives a limit percentage and the setting that gave it as
+// text, such as "50 from SWWAF_ASN_LIMIT_PERCENT", or none when both are
+// left out.
+func percentText(percent *int64, setting string) string {
+	switch {
+	case percent == nil && setting == "":
+		return none
+	case percent == nil:
+		return "none from " + setting
+	default:
+		return fmt.Sprintf("%d from %s", *percent, setting)
+	}
+}

internal/proxy/bodies.go

@@ -103,6 +103,48 @@ func (b *responseBody) Close() error {
 	return b.body.Close()
 }
 
+// upgradedConn is the connection to the app once the app has switched
+// protocols, as for a WebSocket. ReverseProxy writes to it what the client
+// sends and reads from it what the app sends, on goroutines of its own,
+// until the connection closes; it counts the bytes each way, for the byte
+// limits.
+type upgradedConn struct {
+	io.ReadWriteCloser
+
+	// fromApp is how many bytes the app has sent, and toApp how many the
+	// client has.
+	fromApp atomic.Int64
+	toApp   atomic.Int64
+}
+
+// Read reads what the app sends.
+func (c *upgradedConn) Read(p []byte) (int, error) {
+	n, err := c.ReadWriteCloser.Read(p)
+	c.fromApp.Add(int64(n))
+
+	return n, err
+}
+
+// Write sends the app what the client sent.
+func (c *upgradedConn) Write(p []byte) (int, error) {
+	n, err := c.ReadWriteCloser.Write(p)
+	c.toApp.Add(int64(n))
+
+	return n, err
+}
+
+// CloseWrite tells the app that the client sends no more, while what the
+// app sends still passes. ReverseProxy calls it once the client has
+// stopped sending, and closes the connection there if it is not supported.
+func (c *upgradedConn) CloseWrite() error {
+	conn, ok := c.ReadWriteCloser.(interface{ CloseWrite() error })
+	if !ok {
+		return http.ErrNotSupported
+	}
+
+	return conn.CloseWrite()
+}
+
 // limitBody returns body, cut off with an *http.MaxBytesError after
 // maxBytes, or unchanged if maxBytes is zero, which is off.
 func limitBody(body io.ReadCloser, maxBytes int64) io.ReadCloser {

internal/proxy/bytelimits_test.go

@@ -0,0 +1,583 @@
+package proxy_test
+
+import (
+	"bufio"
+	"io"
+	"net"
+	"net/http"
+	"net/netip"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/bans"
+	"sneak.berlin/go/smallwebwaf/internal/requestlog"
+)
+
+// The byte limit settings.
+const (
+	bytesLimitPerMinute = "SWWAF_BYTES_LIMIT_PER_MINUTE"
+	bytesLimitPerHour   = "SWWAF_BYTES_LIMIT_PER_HOUR"
+	bytesLimitPerDay    = "SWWAF_BYTES_LIMIT_PER_DAY"
+	bytesCount          = "SWWAF_BYTES_COUNT"
+)
+
+// The values of SWWAF_BYTES_COUNT.
+const (
+	countResponse = "response"
+	countRequest  = "request"
+	countBoth     = "both"
+)
+
+const (
+	// bodyBytes is the size of the body of each request these tests send
+	// with one, and answerBytes that of each answer of the app.
+	bodyBytes   = 30
+	answerBytes = 70
+	// byteLimit is the byte limit these tests set, as a setting: a request
+	// with a body and its answer, 100 bytes, go over it.
+	byteLimit = "99"
+	// minuteBytes is limit_hit for SWWAF_BYTES_LIMIT_PER_MINUTE.
+	minuteBytes = "minute_bytes"
+)
+
+func TestEachByteLimitBansOnceTheResponseHasEnded(t *testing.T) {
+	t.Parallel()
+
+	const scraper = "192.0.2.200"
+
+	for _, tc := range []struct {
+		setting, window string
+		// apart is the time between the two requests, which the window
+		// still covers.
+		apart time.Duration
+	}{
+		{bytesLimitPerMinute, minute, 0},
+		{bytesLimitPerHour, "hour", 2 * time.Minute},
+		{bytesLimitPerDay, "day", 2 * time.Hour},
+	} {
+		t.Run(tc.setting, func(t *testing.T) {
+			t.Parallel()
+
+			s, clk := startWithAnswers(t, map[string]string{
+				tc.setting: byteLimit, metricsToken: token,
+			})
+
+			// 70 bytes are within the limit of 99.
+			line, _ := s.download()
+			if line.LimitHit != "" || line.Offence != "" {
+				t.Errorf("log line has limit_hit %q and offence %q, want neither",
+					line.LimitHit, line.Offence)
+			}
+
+			// 140 bytes are over it. The response is passed on whole, and
+			// then bans the client for an hour.
+			clk.advance(tc.apart)
+			expires := requestlog.FormatTime(clk.Now().Add(time.Hour))
+
+			line, got := s.download()
+			if got.err != nil || len(got.body) != answerBytes ||
+				line.ResponseBytes != answerBytes {
+				t.Errorf("got %d bytes (%v), and the log line has response_bytes %d, "+
+					"want %d", len(got.body), got.err, line.ResponseBytes, answerBytes)
+			}
+
+			if line.LimitHit != tc.window+"_bytes" || line.Offence != requestlog.OffenceLimit ||
+				line.BanExpires != expires {
+				t.Errorf("log line has limit_hit %q, offence %q and ban_expires %q, "+
+					"want %s_bytes, limit and %s", line.LimitHit, line.Offence,
+					line.BanExpires, tc.window, expires)
+			}
+
+			s.get(client, http.StatusForbidden, requestlog.ActionBanned)
+
+			wantMetric(t, s.scrape(scraper), `smallwebwaf_rate_limit_hits_total{`+
+				`instance="`+alertInstance+`",kind="bytes",window="`+tc.window+`"}`, 1)
+		})
+	}
+}
+
+func TestResponseOverAByteLimitByItselfIsPassedOnWhole(t *testing.T) {
+	t.Parallel()
+
+	s, _ := startWithAnswers(t, map[string]string{bytesLimitPerMinute: "50"})
+
+	// The answer's 70 bytes are over the limit of 50 on their own.
+	line, got := s.download()
+	if got.err != nil || len(got.body) != answerBytes || line.LimitHit != minuteBytes {
+		t.Errorf("got %d bytes (%v), and the log line has limit_hit %q, want %d and %s",
+			len(got.body), got.err, line.LimitHit, answerBytes, minuteBytes)
+	}
+
+	s.get(client, http.StatusForbidden, requestlog.ActionBanned)
+}
+
+func TestBytesOfAnAnswerThatBreaksOffAreCounted(t *testing.T) {
+	t.Parallel()
+
+	s, clk, _, _ := startAppWithAlerts(t, breakOff, map[string]string{
+		bytesLimitPerMinute: "50",
+	})
+	expires := requestlog.FormatTime(clk.Now().Add(time.Hour))
+
+	// The 70 bytes passed on before the app broke off are over the limit of
+	// 50, and ban the client for an hour.
+	line, got := s.requestWithBody(http.MethodGet, client, "/", "", "", http.StatusOK,
+		requestlog.ActionUpstreamError)
+	if len(got.body) != answerBytes || line.LimitHit != minuteBytes ||
+		line.BanExpires != expires {
+		t.Errorf("got %d bytes, and the log line has limit_hit %q and ban_expires %q, "+
+			"want %d, %s and %s", len(got.body), line.LimitHit, line.BanExpires,
+			answerBytes, minuteBytes, expires)
+	}
+
+	s.get(client, http.StatusForbidden, requestlog.ActionBanned)
+}
+
+func TestWebSocketBytesAreCountedOnceItCloses(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		setting string
+		counted float64
+	}{
+		{countResponse, answerBytes},
+		{countRequest, bodyBytes},
+		{countBoth, bodyBytes + answerBytes},
+	} {
+		t.Run(tc.setting, func(t *testing.T) {
+			t.Parallel()
+
+			s, _, _, _ := startAppWithAlerts(t, answerAfterUpgrade, map[string]string{
+				bytesLimitPerMinute: "29", bytesCount: tc.setting,
+			})
+
+			// The client sends 30 bytes and the app 70, each over the limit
+			// of 29, which bans the client once the WebSocket has closed.
+			line := s.webSocket()
+			if line.LimitHit != minuteBytes || line.Counts.MinuteBytes != tc.counted {
+				t.Errorf("log line has limit_hit %q and minute_bytes %v, want %s and %v",
+					line.LimitHit, line.Counts.MinuteBytes, minuteBytes, tc.counted)
+			}
+
+			s.get(client, http.StatusForbidden, requestlog.ActionBanned)
+		})
+	}
+}
+
+func TestWebSocketPassesTheAnswerAfterTheClientStopsSending(t *testing.T) {
+	t.Parallel()
+
+	app := startApp(t, echoOnceTheClientStops)
+	addr, out := startProxy(t, app.URL,
+		map[string]string{trustedProxies: trustLocalhost})
+	s := &sender{t: t, addr: addr, out: out}
+
+	conn, reader := s.openWebSocket()
+	send(t, conn, uploadBody)
+
+	// The client closes its sending side and waits for the answer, which the
+	// app sends only once it has seen the client stop. smallwebwaf passes the
+	// close on to the app through CloseWrite on upgradedConn; without that,
+	// it closes both connections, and the answer is lost.
+	tcp, ok := conn.(*net.TCPConn)
+	if !ok {
+		t.Fatalf("connection is a %T, want a *net.TCPConn", conn)
+	}
+
+	err := tcp.CloseWrite()
+	if err != nil {
+		t.Fatalf("close the sending side: %v", err)
+	}
+
+	got, err := io.ReadAll(reader)
+	if err != nil || string(got) != uploadBody {
+		t.Errorf("got %q (%v), want %q", got, err, uploadBody)
+	}
+
+	s.closeWebSocket(conn)
+}
+
+func TestBytesCountSaysWhichBytesCount(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		setting string
+		// each is the bytes each request counts, and breaking the request
+		// that goes over the limit of 99.
+		each     float64
+		breaking int
+	}{
+		{countResponse, answerBytes, 2},
+		{countRequest, bodyBytes, 4},
+		{countBoth, bodyBytes + answerBytes, 1},
+	} {
+		t.Run(tc.setting, func(t *testing.T) {
+			t.Parallel()
+
+			s, _ := startWithAnswers(t, map[string]string{
+				bytesLimitPerMinute: byteLimit, bytesCount: tc.setting,
+			})
+
+			for i := 1; i <= tc.breaking; i++ {
+				line := s.upload()
+
+				want := ""
+				if i == tc.breaking {
+					want = minuteBytes
+				}
+
+				counted := float64(i) * tc.each
+				if line.LimitHit != want || line.Counts.MinuteBytes != counted {
+					t.Errorf("request %d: log line has limit_hit %q and minute_bytes %v, "+
+						"want %q and %v", i, line.LimitHit, line.Counts.MinuteBytes,
+						want, counted)
+				}
+			}
+
+			s.get(client, http.StatusForbidden, requestlog.ActionBanned)
+		})
+	}
+}
+
+func TestByteLimitsLeaveOutWhatTheRateLimitsLeaveOut(t *testing.T) {
+	t.Parallel()
+
+	const (
+		allowed = "192.0.2.7"  // in SWWAF_ALLOW_NETS
+		exempt  = "192.0.2.10" // in SWWAF_RATE_LIMIT_EXEMPT_NETS
+	)
+
+	s, _ := startWithAnswers(t, map[string]string{
+		bytesLimitPerMinute:  byteLimit,
+		allowNets:            allowed,
+		rateLimitExemptNets:  exempt,
+		rateLimitExemptPaths: "/assets/",
+	})
+
+	// Each sends 200 bytes, none of which is counted.
+	for _, sent := range []struct{ from, path string }{
+		{allowed, "/"}, {exempt, "/"}, {client, "/assets/app.js"},
+	} {
+		for range 2 {
+			line, _ := s.requestWithBody(http.MethodPost, sent.from, sent.path,
+				uploadHeader, uploadBody, http.StatusOK, requestlog.ActionForward)
+			if _, counted := line.fields["counts"]; counted || line.LimitHit != "" {
+				t.Errorf("%s %s: log line has counts %v and limit_hit %q, want neither",
+					sent.from, sent.path, line.fields["counts"], line.LimitHit)
+			}
+		}
+	}
+
+	// A path that is not exempt is counted, and breaks the limit.
+	line := s.upload()
+	if line.LimitHit != minuteBytes {
+		t.Errorf("log line has limit_hit %q, want %s", line.LimitHit, minuteBytes)
+	}
+}
+
+func TestByteLimitsOffCountTheBytesAndBanNoOne(t *testing.T) {
+	t.Parallel()
+
+	const off = "off"
+
+	s, _ := startWithAnswers(t, map[string]string{
+		bytesLimitPerMinute: off, bytesLimitPerHour: off, bytesLimitPerDay: off,
+	})
+
+	for i := 1; i <= 3; i++ {
+		line := s.upload()
+
+		counted := float64(i * (bodyBytes + answerBytes))
+		if line.LimitHit != "" || line.Counts.MinuteBytes != counted ||
+			line.Counts.HourBytes != counted || line.Counts.DayBytes != counted {
+			t.Errorf("request %d: log line has limit_hit %q and counts %+v, "+
+				"want none and %v bytes in each window", i, line.LimitHit,
+				line.Counts, counted)
+		}
+	}
+}
+
+func TestBanForABrokenByteLimitHasItsNotesAndItsAlert(t *testing.T) {
+	t.Parallel()
+
+	s, clk, server, queue := startAppWithAlerts(t, readAndAnswer, map[string]string{
+		bytesLimitPerMinute: byteLimit,
+	})
+	start := clk.Now()
+
+	s.requestWithBody(http.MethodPost, client, "/upload?part=1", uploadHeader,
+		uploadBody, http.StatusOK, requestlog.ActionForward)
+
+	netblock := netip.MustParsePrefix(client + "/32")
+	want := bans.Ban{
+		Netblock: netblock,
+		Start:    start,
+		Expires:  start.Add(time.Hour),
+		Cause:    bans.CauseLimit,
+		Reason:   "bytes per minute over the limit of " + byteLimit,
+		Notes: bans.Notes{
+			Kind:   "bytes",
+			Limit:  99,
+			Window: minute,
+			Count:  bodyBytes + answerBytes,
+			// The request as it was answered, by the app.
+			Request: bans.Request{
+				Time:      start,
+				Method:    http.MethodPost,
+				Host:      appHost,
+				Path:      "/upload?part=1",
+				Status:    http.StatusOK,
+				UserAgent: userAgent,
+			},
+			Requests: 1,
+		},
+	}
+
+	got := server.Ledger.Bans(netblock)
+	if len(got) != 1 || got[0] != want {
+		t.Fatalf("bans\n%+v\nwant\n%+v", got, want)
+	}
+
+	wantAlerts(t, queue, banAlert(alerts.EventBan, start, client, want,
+		requestlog.FormatTime(want.Expires)))
+
+	if offences := historyOf(t, server, client).Offences.Limit; offences != 1 {
+		t.Errorf("history counts %d offences for a limit, want 1", offences)
+	}
+}
+
+func TestObserveModeLogsAndAlertsAByteLimitAndBansNoOne(t *testing.T) {
+	t.Parallel()
+
+	s, clk, server, queue := startAppWithAlerts(t, readAndAnswer, map[string]string{
+		mode:                observe,
+		bytesLimitPerMinute: byteLimit,
+	})
+	start := clk.Now()
+
+	// No ban sets the client's counters back to zero, so each request
+	// breaks the limit again. The answer is the app's either way, and the
+	// alert for the ban is not sent twice within the cooldown.
+	for range 2 {
+		line := s.upload()
+		wantWouldAction(t, line, "")
+
+		if line.LimitHit != minuteBytes || line.Offence != requestlog.OffenceLimit ||
+			line.BanExpires != "" {
+			t.Errorf("log line has limit_hit %q, offence %q and ban_expires %q, "+
+				"want %s, limit and none", line.LimitHit, line.Offence, line.BanExpires,
+				minuteBytes)
+		}
+	}
+
+	if held := server.Ledger.Snapshot(); len(held) != 0 {
+		t.Errorf("the ledger holds %+v, want no ban", held)
+	}
+
+	waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
+	if len(waiting) != 1 {
+		t.Fatalf("%d alerts wait, want 1: %+v", len(waiting), waiting)
+	}
+
+	notes, _ := waiting[0].Detail["notes"].(bans.Notes)
+	alert := banAlert(alerts.EventBan, start, client, bans.Ban{
+		Netblock: netip.MustParsePrefix(client + "/32"), Cause: bans.CauseLimit,
+		Reason: "bytes per minute over the limit of " + byteLimit, Notes: notes,
+	}, requestlog.FormatTime(start.Add(time.Hour)))
+	alert.Detail["mode"] = observe
+	wantAlerts(t, queue, alert)
+}
+
+func TestObserveModeLeavesOutTheBytesOfARequestEnforceModeRefuses(t *testing.T) {
+	t.Parallel()
+
+	s, _ := startWithAnswers(t, map[string]string{
+		mode:                observe,
+		rateLimitPerMinute:  "1",
+		bytesLimitPerMinute: "150",
+	})
+
+	s.upload()
+
+	// The second request breaks the rate limit, which in enforce mode would
+	// refuse it before the app sent anything, so its 100 bytes are not
+	// counted, and the byte limit is not broken. Its line gives the bytes
+	// counted before it.
+	line := s.upload()
+	wantWouldAction(t, line, requestlog.ActionRateLimited)
+
+	if line.LimitHit != minute || line.Counts.MinuteBytes != bodyBytes+answerBytes {
+		t.Errorf("log line has limit_hit %q and minute_bytes %v, want minute and %d",
+			line.LimitHit, line.Counts.MinuteBytes, bodyBytes+answerBytes)
+	}
+}
+
+// uploadHeader and uploadBody are the header and the body of a request
+// with a body of bodyBytes.
+//
+//nolint:gochecknoglobals // a constant cannot call strings.Repeat
+var (
+	uploadHeader = "Content-Length: " + strconv.Itoa(bodyBytes)
+	uploadBody   = strings.Repeat("u", bodyBytes)
+)
+
+// readAndAnswer is the app of these tests: it reads each request's whole
+// body and answers with answerBytes bytes.
+func readAndAnswer(w http.ResponseWriter, r *http.Request) {
+	_, _ = io.Copy(io.Discard, r.Body)
+	_, _ = io.WriteString(w, strings.Repeat("a", answerBytes))
+}
+
+// breakOff is an app that announces an answer of twice answerBytes, and
+// breaks off after answerBytes.
+func breakOff(w http.ResponseWriter, _ *http.Request) {
+	w.Header().Set("Content-Length", strconv.Itoa(2*answerBytes))
+	_, _ = io.WriteString(w, strings.Repeat("a", answerBytes))
+}
+
+// answerAfterUpgrade is an app that switches protocols, as for a
+// WebSocket, and then answers each line it receives with a line of
+// answerBytes.
+func answerAfterUpgrade(w http.ResponseWriter, _ *http.Request) {
+	conn, buffered, err := http.NewResponseController(w).Hijack()
+	if err != nil {
+		return
+	}
+
+	defer func() {
+		_ = conn.Close()
+	}()
+
+	_, _ = buffered.WriteString("HTTP/1.1 101 Switching Protocols\r\n" +
+		"Connection: Upgrade\r\nUpgrade: websocket\r\n\r\n")
+	_ = buffered.Flush()
+
+	for {
+		_, err := buffered.ReadString('\n')
+		if err != nil {
+			return
+		}
+
+		_, _ = buffered.WriteString(strings.Repeat("a", answerBytes-1) + "\n")
+		_ = buffered.Flush()
+	}
+}
+
+// echoOnceTheClientStops is an app that switches protocols, as for a
+// WebSocket, reads what the client sends until the client stops sending,
+// and then sends it all back.
+func echoOnceTheClientStops(w http.ResponseWriter, _ *http.Request) {
+	conn, buffered, err := http.NewResponseController(w).Hijack()
+	if err != nil {
+		return
+	}
+
+	defer func() {
+		_ = conn.Close()
+	}()
+
+	_, _ = buffered.WriteString("HTTP/1.1 101 Switching Protocols\r\n" +
+		"Connection: Upgrade\r\nUpgrade: websocket\r\n\r\n")
+	_ = buffered.Flush()
+
+	received, _ := io.ReadAll(buffered)
+	_, _ = buffered.Write(received)
+	_ = buffered.Flush()
+}
+
+// webSocket opens a WebSocket from client to answerAfterUpgrade, sends a
+// line of bodyBytes on it, reads the answer, and closes it. It checks the
+// answer, and the log line as request does, and returns the log line.
+func (s *sender) webSocket() logLine {
+	s.t.Helper()
+
+	conn, reader := s.openWebSocket()
+	send(s.t, conn, strings.Repeat("u", bodyBytes-1)+"\n")
+
+	got, err := reader.ReadString('\n')
+	if err != nil || len(got) != answerBytes {
+		s.t.Errorf("got %d bytes (%v), want %d", len(got), err, answerBytes)
+	}
+
+	return s.closeWebSocket(conn)
+}
+
+// openWebSocket sends a request from client to switch protocols, as for a
+// WebSocket, and checks that the app switches. It returns the connection,
+// on which reading fails once waitLimit has passed, and a reader of what
+// the app sends on it.
+func (s *sender) openWebSocket() (net.Conn, *bufio.Reader) {
+	s.t.Helper()
+
+	conn := dial(s.t, s.addr)
+	send(s.t, conn, "GET /socket HTTP/1.1\r\nHost: "+appHost+"\r\n"+forwardedFor+
+		": "+client+"\r\nConnection: Upgrade\r\nUpgrade: websocket\r\n\r\n")
+
+	err := conn.SetReadDeadline(time.Now().Add(waitLimit))
+	if err != nil {
+		s.t.Fatalf("set read deadline: %v", err)
+	}
+
+	reader := bufio.NewReader(conn)
+
+	res, err := http.ReadResponse(reader, nil)
+	if err != nil {
+		s.t.Fatalf("read the answer to the upgrade: %v", err)
+	}
+
+	_ = res.Body.Close()
+
+	if res.StatusCode != http.StatusSwitchingProtocols {
+		s.t.Fatalf("status %d, want %d", res.StatusCode, http.StatusSwitchingProtocols)
+	}
+
+	return conn, reader
+}
+
+// closeWebSocket closes conn, a WebSocket openWebSocket opened, checks its
+// log line as request does, and returns it.
+func (s *sender) closeWebSocket(conn net.Conn) logLine {
+	s.t.Helper()
+
+	_ = conn.Close()
+
+	line := s.out.requestLines(s.t, s.sent+1)[s.sent]
+	s.sent++
+	wantLine(s.t, line, http.StatusSwitchingProtocols, requestlog.ActionForward)
+
+	return line
+}
+
+// startWithAnswers is startAppWithAlerts in front of readAndAnswer, for a
+// test that looks at neither the server nor the alerts.
+func startWithAnswers(t *testing.T, env map[string]string) (*sender, *clock) {
+	t.Helper()
+
+	s, clk, _, _ := startAppWithAlerts(t, readAndAnswer, env)
+
+	return s, clk
+}
+
+// download sends a GET request for / from client, and checks that the
+// app's answer is passed on, as request does. It returns the log line and
+// the answer.
+func (s *sender) download() (logLine, answer) {
+	s.t.Helper()
+
+	return s.requestWithBody(http.MethodGet, client, "/", "", "", http.StatusOK,
+		requestlog.ActionForward)
+}
+
+// upload is download for a POST request with a body of bodyBytes, and
+// returns the log line.
+func (s *sender) upload() logLine {
+	s.t.Helper()
+
+	line, _ := s.requestWithBody(http.MethodPost, client, "/", uploadHeader,
+		uploadBody, http.StatusOK, requestlog.ActionForward)
+
+	return line
+}

internal/proxy/lookup.go

@@ -22,8 +22,9 @@ const (
 // database or through GeoJS, and notes them for the log line, unless
 // SWWAF_LOOKUP_SOURCE is off or the client is on a private, loopback or
 // link-local address, which no lookup can place. The lookup database
-// answers at once. With GeoJS, while a setting needs the answer, a new
-// client's request waits for it. ctx is the request's own context.
+// answers at once. With GeoJS, while a setting needs the answer, such as a
+// country list or a biased threshold, a new client's request waits for it.
+// ctx is the request's own context.
 func (rq *request) lookUp(ctx context.Context) {
 	if rq.h.config.LookupSource == "off" || !canBePlaced(rq.client) {
 		return

internal/proxy/lookup_test.go

@@ -22,6 +22,10 @@ import (
 // and country.
 type asnAndCountry struct{ asn, asName, country string }
 
+// fileSource is the SWWAF_LOOKUP_SOURCE that looks clients up in the
+// lookup database.
+const fileSource = "file"
+
 func TestEveryClientIsLookedUpWithoutWaitingWhileNoSettingNeedsIt(t *testing.T) {
 	t.Parallel()
 
@@ -178,7 +182,7 @@ func TestClientsAreLookedUpInTheLookupDatabaseAndGeoJSIsNotAsked(t *testing.T) {
 		fromKP + "/32": {ASN: asnKP, ASName: asNameKP, Country: "KP"},
 	})
 	s, clk, server := startWithClock(t, geojsURL, map[string]string{
-		lookupSource:       "file",
+		lookupSource:       fileSource,
 		lookupDBPath:       path,
 		allowedCountries:   "DE",
 		rateLimitPerMinute: "1",
@@ -345,6 +349,7 @@ const unansweredGeoJSURL = "unanswered://geojs/v1/ip/geo.json"
 func TestMain(m *testing.M) {
 	transport, _ := http.DefaultTransport.(*http.Transport)
 	transport.RegisterProtocol("unanswered", unansweredGeoJS{})
+	transport.RegisterProtocol("abuseipdb", abuseIPDBStandIn{})
 
 	m.Run()
 }

internal/proxy/metrics_test.go

@@ -222,8 +222,8 @@ func TestMetricsCountLimitsAndBans(t *testing.T) {
 	metrics := s.scrape(scraper)
 	wantMetric(t, metrics,
 		`smallwebwaf_requests_total{action="denied",instance="app",status_class="none"}`, 1)
-	wantMetric(t, metrics,
-		`smallwebwaf_rate_limit_hits_total{instance="app",window="minute"}`, 1)
+	wantMetric(t, metrics, `smallwebwaf_rate_limit_hits_total{instance="app",`+
+		`kind="requests",window="minute"}`, 1)
 	wantMetric(t, metrics, `smallwebwaf_offences_total{instance="app",kind="limit"}`, 1)
 	wantMetric(t, metrics, `smallwebwaf_bans_made_total{cause="limit",instance="app"}`, 1)
 	wantMetric(t, metrics, `smallwebwaf_active_bans{instance="app"}`, 1)
@@ -238,8 +238,8 @@ func TestMetricsCountLimitsAndBans(t *testing.T) {
 	s.get(client, 0, requestlog.ActionRateLimited)
 
 	metrics = s.scrape(scraper)
-	wantMetric(t, metrics,
-		`smallwebwaf_rate_limit_hits_total{instance="app",window="minute"}`, 2)
+	wantMetric(t, metrics, `smallwebwaf_rate_limit_hits_total{instance="app",`+
+		`kind="requests",window="minute"}`, 2)
 	wantMetric(t, metrics, `smallwebwaf_offences_total{instance="app",kind="limit"}`, 2)
 	wantMetric(t, metrics, `smallwebwaf_bans_made_total{cause="limit",instance="app"}`, 2)
 	wantMetric(t, metrics, `smallwebwaf_active_bans{instance="app"}`, 1)

internal/proxy/passthrough_test.go

@@ -122,6 +122,8 @@ func wantAnswer(t *testing.T, got answer, body []byte) {
 func wantRequestFields(t *testing.T, line logLine, host string, sent, received int) {
 	t.Helper()
 
+	bytes := float64(sent + received)
+
 	want := withTimings(line, requestlog.Line{
 		Type: requestType, Time: line.Time, Instance: "app",
 		ClientIP: localhost, Method: http.MethodPatch, Scheme: plain, Host: host,
@@ -131,7 +133,10 @@ func wantRequestFields(t *testing.T, line logLine, host string, sent, received i
 		RequestID: line.RequestID, PeerIP: localhost, ClientGroup: localhost + "/32",
 		ContentLength: int64(sent), ResponseContentType: "text/plain; charset=utf-8",
 		UpstreamStatus: http.StatusTeapot, Action: requestlog.ActionForward,
-		Counts: ratelimit.Counts{Minute: 1, Hour: 1, Day: 1},
+		Counts: ratelimit.Counts{
+			Minute: 1, Hour: 1, Day: 1,
+			MinuteBytes: bytes, HourBytes: bytes, DayBytes: bytes,
+		},
 	})
 	if !reflect.DeepEqual(line.Line, want) {
 		t.Errorf("log line\n%+v\nwant\n%+v", line.Line, want)

internal/proxy/proxy.go

@@ -12,11 +12,13 @@ import (
 	"time"
 
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/anomaly"
 	"sneak.berlin/go/smallwebwaf/internal/bans"
 	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/lookup"
 	"sneak.berlin/go/smallwebwaf/internal/metrics"
 	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
+	"sneak.berlin/go/smallwebwaf/internal/reputation"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
 	"sneak.berlin/go/smallwebwaf/internal/rules"
 )
@@ -57,6 +59,9 @@ type Params struct {
 	// GeoJSURL is where clients' AS numbers and countries are looked up
 	// while SWWAF_LOOKUP_SOURCE is geojs, normally lookup.URL.
 	GeoJSURL string
+	// AbuseIPDBURL is where clients are checked with AbuseIPDB while
+	// SWWAF_ABUSEIPDB_KEY is set, normally reputation.AbuseIPDBURL.
+	AbuseIPDBURL string
 	// LookupFile is the lookup database they are looked up in while
 	// SWWAF_LOOKUP_SOURCE is file, and nil otherwise.
 	LookupFile *lookup.File
@@ -68,20 +73,29 @@ type Params struct {
 	// against.
 	Rules *rules.Files
 	// Alerts receive the alert for each ban the proxy makes or makes
-	// permanent, and for GeoJS failing.
+	// permanent, for each count over an anomaly threshold, for each request
+	// whose client a blocklist, a DNSBL zone or AbuseIPDB lists, and for
+	// GeoJS failing, a fetch of a list failing, a query to a DNSBL zone or
+	// a check with AbuseIPDB failing, or the day's AbuseIPDB checks used up.
 	Alerts *alerts.Queue
 }
 
 // Server is the server smallwebwaf runs, with the parts of the proxy
 // whose state the state files keep, the lookup database, nil unless
-// SWWAF_LOOKUP_SOURCE is file, and the metrics.
+// SWWAF_LOOKUP_SOURCE is file, the lists fetched from URLs, which its Run
+// fetches, the DNSBL zones' verdicts, AbuseIPDB's scores and checks
+// spent, and the metrics.
 type Server struct {
 	*http.Server
 
 	Ledger     *bans.Ledger
 	Limiter    *ratelimit.Limiter
 	GeoJS      *lookup.GeoJS
+	Anomalies  *anomaly.Counters
 	LookupFile *lookup.File
+	Lists      *reputation.Lists
+	DNSBL      *reputation.DNSBL
+	AbuseIPDB  *reputation.AbuseIPDB
 	Metrics    *metrics.Metrics
 }
 
@@ -94,6 +108,7 @@ type Server struct {
 func New(params Params) *Server {
 	errorLog := slog.NewLogLogger(params.ProcessLog.Handler(), slog.LevelWarn)
 	m := metrics.New(params.Config.MetricsTopN, params.Config.InstanceName)
+	lists, dnsbl, abuseIPDB := newReputation(params, m)
 	h := &handler{
 		config:     params.Config,
 		requestLog: params.RequestLog,
@@ -103,9 +118,12 @@ func New(params Params) *Server {
 		now:        params.Now,
 		metrics:    m,
 		limiter: ratelimit.New(ratelimit.Limits{
-			PerMinute: params.Config.RateLimitPerMinute,
-			PerHour:   params.Config.RateLimitPerHour,
-			PerDay:    params.Config.RateLimitPerDay,
+			PerMinute:      params.Config.RateLimitPerMinute,
+			PerHour:        params.Config.RateLimitPerHour,
+			PerDay:         params.Config.RateLimitPerDay,
+			BytesPerMinute: params.Config.BytesLimitPerMinute,
+			BytesPerHour:   params.Config.BytesLimitPerHour,
+			BytesPerDay:    params.Config.BytesLimitPerDay,
 		}),
 		ledger: bans.New(bans.Rules{
 			LimitBanDuration:     params.Config.LimitBanDuration,
@@ -114,18 +132,32 @@ func New(params Params) *Server {
 			AttackBanDuration:    params.Config.AttackBanDuration,
 			MaxBans:              params.Config.MaxBans,
 		}),
+		anomalies: anomaly.New(anomaly.Params{
+			Client:         params.Config.AnomalyClient,
+			Net:            params.Config.AnomalyNet,
+			ASN:            params.Config.AnomalyASN,
+			Total:          params.Config.AnomalyTotal,
+			Watch:          params.Config.AnomalyWatch,
+			NetV4Prefix:    params.Config.AnomalyNetV4Prefix,
+			NetV6Prefix:    params.Config.AnomalyNetV6Prefix,
+			NamedNetblocks: params.Config.WatchNets,
+			Alerts:         params.Alerts,
+		}),
 		lookupFile: params.LookupFile,
+		lists:      lists,
+		dnsbl:      dnsbl,
+		abuseIPDB:  abuseIPDB,
 		rules:      params.Rules,
 		alerts:     params.Alerts,
 	}
 	h.geojs = lookup.New(lookup.Params{
 		URL:     params.GeoJSURL,
 		Timeout: params.Config.LookupTimeout,
-		// The country lists and the headers act on the answer before the
-		// request goes on.
+		// The country lists, the headers and the biased thresholds act on
+		// the answer before the request goes on.
 		Wait: len(params.Config.DeniedCountries) > 0 ||
 			len(params.Config.ExclusivelyAllowedCountries) > 0 ||
-			params.Config.AddLookupHeaders,
+			params.Config.AddLookupHeaders || biasedThresholdsSet(params.Config),
 		Answered:   h.addLookup,
 		Now:        params.Now,
 		ProcessLog: params.ProcessLog,
@@ -151,11 +183,49 @@ func New(params Params) *Server {
 		Ledger:     h.ledger,
 		Limiter:    h.limiter,
 		GeoJS:      h.geojs,
+		Anomalies:  h.anomalies,
 		LookupFile: h.lookupFile,
+		Lists:      h.lists,
+		DNSBL:      h.dnsbl,
+		AbuseIPDB:  h.abuseIPDB,
 		Metrics:    m,
 	}
 }
 
+// newReputation returns the lists fetched from URLs, the DNSBL zones'
+// verdicts and AbuseIPDB's scores, as the settings in params name them,
+// with none fetched, asked for or checked yet, and adds their metrics to
+// m, AbuseIPDB's while SWWAF_ABUSEIPDB_KEY is set.
+func newReputation(
+	params Params, m *metrics.Metrics,
+) (*reputation.Lists, *reputation.DNSBL, *reputation.AbuseIPDB) {
+	cfg := params.Config
+	lists := reputation.New(reputation.Params{
+		BlocklistURLs: cfg.BlocklistURLs, Refresh: cfg.BlocklistRefresh,
+		ASNLimitPercentURL: cfg.ASNLimitPercentURL, Now: params.Now,
+		ProcessLog: params.ProcessLog, Alerts: params.Alerts,
+	})
+	dnsbl := reputation.NewDNSBL(reputation.DNSBLParams{
+		Zones: cfg.DNSBLZones, Resolver: cfg.DNSBLResolver, CacheTTL: cfg.ReputationCacheTTL,
+		Timeout: cfg.ReputationTimeout, Now: params.Now, ProcessLog: params.ProcessLog,
+		Alerts: params.Alerts,
+	})
+	abuseIPDB := reputation.NewAbuseIPDB(reputation.AbuseIPDBParams{
+		URL: params.AbuseIPDBURL, Key: cfg.AbuseIPDBKey, MinScore: cfg.AbuseIPDBMinScore,
+		DailyBudget: cfg.AbuseIPDBDailyBudget, CacheTTL: cfg.ReputationCacheTTL,
+		Timeout: cfg.ReputationTimeout, Now: params.Now, ProcessLog: params.ProcessLog,
+		Alerts: params.Alerts,
+	})
+
+	m.AddReputation(lists, dnsbl)
+
+	if cfg.AbuseIPDBKey != "" {
+		m.AddAbuseIPDB(abuseIPDB)
+	}
+
+	return lists, dnsbl, abuseIPDB
+}
+
 // handler is the proxy. It holds what every request shares; what belongs
 // to one request is in a request.
 type handler struct {
@@ -169,7 +239,11 @@ type handler struct {
 	limiter    *ratelimit.Limiter
 	ledger     *bans.Ledger
 	geojs      *lookup.GeoJS
+	anomalies  *anomaly.Counters
 	lookupFile *lookup.File
+	lists      *reputation.Lists
+	dnsbl      *reputation.DNSBL
+	abuseIPDB  *reputation.AbuseIPDB
 	rules      *rules.Files
 	alerts     *alerts.Queue
 }
@@ -208,6 +282,7 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	// Once the request has ended, before its log line is written.
 	defer rq.addToHistory()
+	defer rq.countAnomalies()
 
 	refused := rq.check(r.Context())
 	rq.checked = time.Now()
@@ -226,5 +301,10 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// Once the response has ended, before the request is added to its
+	// client's history. Deferred, since ReverseProxy panics to end a
+	// response it cannot finish.
+	defer rq.countBytes()
+
 	rq.forward(r.Context())
 }

internal/proxy/proxy_test.go

@@ -268,7 +268,8 @@ func startProxyWithAlerts(
 // queue: they wait in it, for the test to look at. With no geojsURL, there
 // is no stand-in for GeoJS to look clients up at, and SWWAF_LOOKUP_SOURCE
 // is off unless env sets it. While it is file, the lookup database
-// SWWAF_LOOKUP_DB_PATH names is read.
+// SWWAF_LOOKUP_DB_PATH names is read. Clients are checked with AbuseIPDB
+// at abuseIPDBURL while env sets SWWAF_ABUSEIPDB_KEY.
 func newProxy(
 	t *testing.T, appURL, geojsURL string, now func() time.Time,
 	env map[string]string,
@@ -315,7 +316,7 @@ func newProxy(
 
 	var lookupFile *lookup.File
 
-	if cfg.LookupSource == "file" {
+	if cfg.LookupSource == fileSource {
 		lookupFile, err = lookup.OpenFile(lookup.FileParams{
 			Path: cfg.LookupDBPath, Now: now, ProcessLog: processLog, Alerts: alertQueue,
 		})
@@ -325,14 +326,15 @@ func newProxy(
 	}
 
 	server := proxy.New(proxy.Params{
-		Config:     cfg,
-		RequestLog: out,
-		ProcessLog: processLog,
-		GeoJSURL:   geojsURL,
-		LookupFile: lookupFile,
-		Now:        now,
-		Rules:      ruleFiles,
-		Alerts:     alertQueue,
+		Config:       cfg,
+		RequestLog:   out,
+		ProcessLog:   processLog,
+		GeoJSURL:     geojsURL,
+		AbuseIPDBURL: abuseIPDBURL,
+		LookupFile:   lookupFile,
+		Now:          now,
+		Rules:        ruleFiles,
+		Alerts:       alertQueue,
 	})
 
 	return server, out, alertQueue

internal/proxy/reputation.go

@@ -0,0 +1,98 @@
+package proxy
+
+import (
+	"context"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
+	"sneak.berlin/go/smallwebwaf/internal/reputation"
+)
+
+// deny is the SWWAF_BLOCKLIST_ACTION and the SWWAF_REPUTATION_ACTION that
+// refuses the requests of a client a source lists.
+const deny = "deny"
+
+// blocklistDenied notes the blocklists that list the client, as
+// noteListed does, and reports whether SWWAF_BLOCKLIST_ACTION, being deny,
+// refuses the request. Being limit, it lowers the client's limits instead
+// (see limitPercentages), and being log, it does nothing more.
+func (rq *request) blocklistDenied() bool {
+	listedBy := rq.h.lists.ListedBy(rq.client)
+	rq.blocklisted = len(listedBy) > 0
+	rq.noteListed(listedBy, "listed by a blocklist")
+
+	return rq.blocklisted && rq.h.config.BlocklistAction == deny
+}
+
+// dnsblDenied notes the DNSBL zones whose verdict lists the client, as
+// noteListed does, and reports whether SWWAF_REPUTATION_ACTION, being
+// deny, refuses the request. Being limit, it lowers the client's limits
+// instead (see limitPercentages), and being log, it does nothing more. A
+// zone without a verdict on the client is asked about it in the
+// background, and the request does not wait for the answer. ctx is the
+// request's own context.
+func (rq *request) dnsblDenied(ctx context.Context) bool {
+	listedBy := rq.h.dnsbl.ListedBy(ctx, rq.client)
+	rq.dnsblListed = len(listedBy) > 0
+	rq.noteListed(listedBy, "listed by a DNSBL zone")
+
+	return rq.dnsblListed && rq.h.config.ReputationAction == deny
+}
+
+// abuseIPDBDenied notes AbuseIPDB, as noteHit does, with the score, when
+// its score of the client is a hit, and reports whether
+// SWWAF_REPUTATION_ACTION, being deny, refuses the request, as dnsblDenied
+// does for a zone. While SWWAF_ABUSEIPDB_KEY is unset it does nothing. A
+// client without a score is checked in the background, by the request's
+// address, if its history counts an offence, and the request does not
+// wait for the answer. The score is then used for each address of the
+// client. ctx is the request's own context.
+func (rq *request) abuseIPDBDenied(ctx context.Context) bool {
+	if rq.h.config.AbuseIPDBKey == "" {
+		return false
+	}
+
+	client := clientGroup(rq.client)
+	held, _ := rq.h.limiter.Client(client)
+	offender := held.History.Offences != ratelimit.Offences{}
+
+	score, hit := rq.h.abuseIPDB.Hit(ctx, client, rq.client, offender)
+	if !hit {
+		return false
+	}
+
+	rq.abuseIPDBHit = true
+	rq.noteHit(reputation.AbuseIPDBSource, "scored by AbuseIPDB at or over "+
+		"SWWAF_ABUSEIPDB_MIN_SCORE", map[string]any{
+		"source": reputation.AbuseIPDBSource, "score": score,
+	})
+
+	return rq.h.config.ReputationAction == deny
+}
+
+// noteListed notes each of sources, the URLs of the blocklists or the
+// DNSBL zones, their keys masked, that list the client, as noteHit does,
+// with reason, and the source in the alert's detail.
+func (rq *request) noteListed(sources []string, reason string) {
+	for _, source := range sources {
+		rq.noteHit(source, reason, map[string]any{"source": source})
+	}
+}
+
+// noteHit adds source, which lists the client, to the log line's
+// reputation, counts it in the metrics, and raises a reputation_hit alert
+// with reason and detail.
+func (rq *request) noteHit(source, reason string, detail map[string]any) {
+	rq.line.Reputation = append(rq.line.Reputation, source)
+	rq.h.metrics.ReputationHit(source)
+	rq.h.alerts.Raise(alerts.Alert{
+		Event:    alerts.EventReputationHit,
+		Client:   rq.client,
+		Netblock: clientGroup(rq.client),
+		ASN:      rq.line.ASN,
+		ASName:   rq.line.ASName,
+		Country:  rq.line.Country,
+		Reason:   reason,
+		Detail:   detail,
+	})
+}

internal/proxy/reputation_test.go

@@ -0,0 +1,960 @@
+package proxy_test
+
+import (
+	"fmt"
+	"io"
+	"maps"
+	"net/http"
+	"net/netip"
+	"slices"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/proxy"
+	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
+	"sneak.berlin/go/smallwebwaf/internal/reputation"
+	"sneak.berlin/go/smallwebwaf/internal/requestlog"
+)
+
+// The reputation settings.
+const (
+	blocklistURLs      = "SWWAF_BLOCKLIST_URLS"
+	blocklistAction    = "SWWAF_BLOCKLIST_ACTION"
+	asnLimitPercentURL = "SWWAF_ASN_LIMIT_PERCENT_URL"
+)
+
+// The actions of SWWAF_BLOCKLIST_ACTION and SWWAF_REPUTATION_ACTION:
+// limitHalf gives a listed client half of every limit, and limitQuarter a
+// quarter.
+const (
+	actionDeny   = "deny"
+	actionLog    = "log"
+	limitHalf    = "limit:50"
+	limitQuarter = "limit:25"
+)
+
+// The lists these tests name, which are never fetched: each test puts in
+// the copies it needs, as reputation.json would at start.
+const (
+	dropURL = "https://lists.example/drop.txt"
+	torURL  = "https://lists.example/tor.txt"
+	asnURL  = "https://lists.example/asn.txt"
+)
+
+func TestEachBlocklistActionForAListedAddressAndAListedNetblock(t *testing.T) {
+	t.Parallel()
+
+	forward, denied := requestlog.ActionForward, requestlog.ActionDenied
+
+	for _, tc := range []struct {
+		action string
+		// statuses and actions are those of a listed client's three
+		// requests, and percent their limit_percent, as percentText gives it.
+		statuses []int
+		actions  []string
+		percent  string
+	}{
+		{
+			actionDeny, []int{http.StatusForbidden, http.StatusForbidden, http.StatusForbidden},
+			[]string{denied, denied, denied}, none,
+		},
+		{
+			// Half of 4 requests a minute: the third breaks the limit.
+			limitHalf, []int{http.StatusOK, http.StatusOK, http.StatusForbidden},
+			[]string{forward, forward, requestlog.ActionRateLimited},
+			"50 from " + blocklistAction,
+		},
+		{
+			actionLog, []int{http.StatusOK, http.StatusOK, http.StatusOK},
+			[]string{forward, forward, forward}, none,
+		},
+	} {
+		t.Run(tc.action, func(t *testing.T) {
+			t.Parallel()
+
+			s, server, _ := startWithLookups(t, map[string]string{
+				rateLimitPerMinute: fourAMinute, blocklistURLs: dropURL,
+				blocklistAction: tc.action,
+			})
+			// fromDE is listed as an address, and fromKP in a netblock.
+			loadLists(t, server, map[string][]string{
+				dropURL: {"; DROP", fromDE, "198.51.100.0/24 ; SBL1"},
+			})
+
+			for _, from := range []string{fromDE, fromKP} {
+				for i := range 3 {
+					line := s.get(from, tc.statuses[i], tc.actions[i])
+					wantReputation(t, line, dropURL)
+					wantPercent(t, "limit_percent", line.LimitPercent,
+						line.LimitPercentSetting, tc.percent)
+
+					// A request refused for the list is not counted.
+					counted := line.fields["counts"] != nil
+					if counted != (tc.actions[i] != denied) {
+						t.Errorf("request from %s counted %t, logged %s", from, counted,
+							tc.actions[i])
+					}
+				}
+			}
+
+			// A client no list lists has the whole limit.
+			for range 3 {
+				line := s.get(unplaced, http.StatusOK, forward)
+				wantReputation(t, line)
+				wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+					none)
+			}
+
+			// A refusal for the list makes no ban.
+			if held := server.Ledger.Snapshot(); tc.action == actionDeny && len(held) != 0 {
+				t.Errorf("bans %+v, want none", held)
+			}
+		})
+	}
+}
+
+func TestBlocklistsComeAfterTheCountryListsAndSkipAllowNets(t *testing.T) {
+	t.Parallel()
+
+	s, server, queue := startWithLookups(t, map[string]string{
+		blocklistURLs: dropURL, deniedCountries: "kp", allowNets: fromDE,
+	})
+	loadLists(t, server, map[string][]string{dropURL: {fromDE, fromKP}})
+
+	// fromKP's country refuses it before the list is looked at, and fromDE,
+	// in SWWAF_ALLOW_NETS, is not checked at all: neither is noted, nor
+	// alerted.
+	wantReputation(t, s.get(fromKP, http.StatusForbidden, requestlog.ActionCountryDenied))
+	wantReputation(t, s.get(fromDE, http.StatusOK, requestlog.ActionForward))
+	wantAlerts(t, queue)
+}
+
+func TestObserveModeForwardsAClientABlocklistDeniesAndAlertsIt(t *testing.T) {
+	t.Parallel()
+
+	s, server, queue := startWithLookups(t, map[string]string{
+		blocklistURLs: dropURL, mode: observe,
+	})
+	loadLists(t, server, map[string][]string{dropURL: {fromDE}})
+
+	line := s.get(fromDE, http.StatusOK, requestlog.ActionForward)
+	wantWouldAction(t, line, requestlog.ActionDenied)
+	wantReputation(t, line, dropURL)
+
+	waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
+	if len(waiting) != 1 || waiting[0].Event != alerts.EventReputationHit {
+		t.Errorf("alerts waiting %+v, want a reputation_hit alert", waiting)
+	}
+}
+
+func TestBlocklistLimitTakesPartInTheLowestPercentageOfEveryLimit(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		action, asnPercent string
+		// want is the upload's limit_percent and bytes_percent, as
+		// percentText gives them, and limitHit its limit_hit.
+		want, limitHit string
+	}{
+		{limitHalf, asnDEQuarter, "25 from " + asnLimitPercent, minuteBytes},
+		{limitQuarter, asnDEHalf, "25 from " + blocklistAction, minuteBytes},
+		// The AS number's, the first of two alike.
+		{limitQuarter, asnDEQuarter, "25 from " + asnLimitPercent, minuteBytes},
+		{actionLog, asnDE + ":100", none, ""},
+	} {
+		t.Run(tc.action+" "+tc.asnPercent, func(t *testing.T) {
+			t.Parallel()
+
+			s, server, _ := startWithLookups(t, map[string]string{
+				bytesLimitPerMinute: twoUploads, blocklistURLs: dropURL,
+				blocklistAction: tc.action, asnLimitPercent: tc.asnPercent,
+			})
+			loadLists(t, server, map[string][]string{dropURL: {fromDE}})
+
+			// The upload's 100 bytes are over 49, a quarter of 199, and 99,
+			// half of it, and within 199.
+			line := s.uploadFrom(fromDE)
+			wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+				tc.want)
+			wantPercent(t, "bytes_percent", line.BytesPercent, line.BytesPercentSetting,
+				tc.want)
+
+			if line.LimitHit != tc.limitHit {
+				t.Errorf("log line has limit_hit %q, want %q", line.LimitHit, tc.limitHit)
+			}
+		})
+	}
+}
+
+func TestASNLimitPercentFileCountsAsTheSettingDoesTheLowerWinning(t *testing.T) {
+	t.Parallel()
+
+	const (
+		fromURL     = "25 from " + asnLimitPercentURL
+		fromSetting = "25 from " + asnLimitPercent
+	)
+
+	for _, tc := range []struct {
+		name string
+		env  map[string]string
+		file string
+		// limitPercent and bytesPercent are the upload's, as percentText
+		// gives them.
+		limitPercent, bytesPercent string
+	}{
+		{"the file's alone", nil, asnDEQuarter, fromURL, fromURL},
+		{
+			"the file's, lower than the setting's",
+			map[string]string{asnLimitPercent: asnDEHalf}, asnDEQuarter, fromURL, fromURL,
+		},
+		{
+			"the setting's, lower than the file's",
+			map[string]string{asnLimitPercent: asnDEQuarter}, asnDEHalf,
+			fromSetting, fromSetting,
+		},
+		{
+			"the setting's, the first of two alike",
+			map[string]string{asnLimitPercent: asnDEQuarter}, asnDEQuarter,
+			fromSetting, fromSetting,
+		},
+		{"none, for an AS number the file does not list", nil, asnKP + ":25", none, none},
+		{
+			"SWWAF_ASN_BYTES_PERCENT's in place of the file's for the byte limits",
+			map[string]string{asnBytesPercent: asnDE + ":100"}, asnDEQuarter, fromURL, none,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			env := map[string]string{asnLimitPercentURL: asnURL}
+			maps.Copy(env, tc.env)
+
+			s, server, _ := startWithLookups(t, env)
+			loadLists(t, server, map[string][]string{asnURL: {"# by AS number", tc.file}})
+
+			line := s.uploadFrom(fromDE)
+			wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+				tc.limitPercent)
+			wantPercent(t, "bytes_percent", line.BytesPercent, line.BytesPercentSetting,
+				tc.bytesPercent)
+		})
+	}
+}
+
+func TestEachBlocklistThatListsAClientRaisesAnAlertOncePerCooldownAndIsCounted(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	const emptyURL = "https://lists.example/empty.txt"
+
+	s, clk, server, queue := startWithLookupsAndClock(t, map[string]string{
+		blocklistURLs:   dropURL + "," + torURL + "," + emptyURL,
+		blocklistAction: actionLog,
+		metricsToken:    token,
+	})
+	loadLists(t, server, map[string][]string{dropURL: {fromDE}, torURL: {fromDE}})
+
+	// The second request's alerts are repeats, which the cooldown holds
+	// back.
+	for range 2 {
+		wantReputation(t, s.get(fromDE, http.StatusOK, requestlog.ActionForward),
+			dropURL, torURL)
+	}
+
+	hit := func(source string) alerts.Alert {
+		return alerts.Alert{
+			Instance: alertInstance,
+			Time:     clk.Now(),
+			Event:    alerts.EventReputationHit,
+			Client:   netip.MustParseAddr(fromDE),
+			Netblock: netip.MustParsePrefix(fromDE + "/32"),
+			ASN:      asnDE,
+			ASName:   asNameDE,
+			Country:  "DE",
+			Reason:   "listed by a blocklist",
+			Detail:   map[string]any{"source": source},
+		}
+	}
+	wantAlerts(t, queue, hit(dropURL), hit(torURL))
+
+	if queue.Suppressed() != 2 {
+		t.Errorf("%d alerts held back, want the second request's 2", queue.Suppressed())
+	}
+
+	// Each list's hits, none of its fetches failed, and when its copy was
+	// fetched, 0 for the one without.
+	metrics := s.scrape(unplaced)
+	fetched := float64(listsFetched().Unix())
+
+	for listURL, want := range map[string]struct{ hits, fetched float64 }{
+		dropURL: {2, fetched}, torURL: {2, fetched}, emptyURL: {0, 0},
+	} {
+		labels := `{instance="` + alertInstance + `",source="` + listURL + `"}`
+
+		if want.hits == 0 {
+			wantNoSeries(t, metrics, "smallwebwaf_reputation_hits_total"+labels)
+		} else {
+			wantMetric(t, metrics, "smallwebwaf_reputation_hits_total"+labels, want.hits)
+		}
+
+		wantMetric(t, metrics, "smallwebwaf_reputation_failures_total"+labels, 0)
+		wantMetric(t, metrics, "smallwebwaf_reputation_last_fetch_timestamp_seconds"+labels,
+			want.fetched)
+	}
+}
+
+// The DNSBL settings.
+const (
+	dnsblZones       = "SWWAF_DNSBL_ZONES"
+	dnsblResolver    = "SWWAF_DNSBL_RESOLVER"
+	reputationAction = "SWWAF_REPUTATION_ACTION"
+)
+
+// The DNSBL zones these tests name, which are never asked about the
+// clients the tests send requests from: each test puts in the verdicts it
+// needs, as reputation.json would at start. A query a test does start is
+// sent to noResolver, where nothing listens, so that none leaves the host.
+const (
+	dnsblZone  = "dnsbl.example"
+	otherZone  = "other.example"
+	noResolver = "127.0.0.1:9"
+)
+
+func TestEachReputationActionForAClientADNSBLZoneLists(t *testing.T) {
+	t.Parallel()
+
+	forward, denied := requestlog.ActionForward, requestlog.ActionDenied
+
+	for _, tc := range []struct {
+		action string
+		// statuses and actions are those of a listed client's three
+		// requests, and percent their limit_percent, as percentText gives it.
+		statuses []int
+		actions  []string
+		percent  string
+	}{
+		{
+			actionDeny, []int{http.StatusForbidden, http.StatusForbidden, http.StatusForbidden},
+			[]string{denied, denied, denied}, none,
+		},
+		{
+			// Half of 4 requests a minute: the third breaks the limit.
+			limitHalf, []int{http.StatusOK, http.StatusOK, http.StatusForbidden},
+			[]string{forward, forward, requestlog.ActionRateLimited},
+			"50 from " + reputationAction,
+		},
+		{
+			actionLog, []int{http.StatusOK, http.StatusOK, http.StatusOK},
+			[]string{forward, forward, forward}, none,
+		},
+	} {
+		t.Run(tc.action, func(t *testing.T) {
+			t.Parallel()
+
+			s, server, _ := startWithLookups(t, map[string]string{
+				rateLimitPerMinute: fourAMinute, dnsblZones: dnsblZone + "," + otherZone,
+				dnsblResolver: noResolver, reputationAction: tc.action,
+			})
+			listedBy := map[string][]string{
+				fromDE: {dnsblZone, otherZone}, fromKP: {otherZone}, unplaced: nil,
+			}
+			loadVerdicts(server, listedBy)
+
+			for _, from := range []string{fromDE, fromKP} {
+				for i := range 3 {
+					line := s.get(from, tc.statuses[i], tc.actions[i])
+					// In the order SWWAF_DNSBL_ZONES names them.
+					wantReputation(t, line, listedBy[from]...)
+					wantPercent(t, "limit_percent", line.LimitPercent,
+						line.LimitPercentSetting, tc.percent)
+
+					// A request refused for the verdict is not counted.
+					counted := line.fields["counts"] != nil
+					if counted != (tc.actions[i] != denied) {
+						t.Errorf("request from %s counted %t, logged %s", from, counted,
+							tc.actions[i])
+					}
+				}
+			}
+
+			// A client no zone lists has the whole limit.
+			for range 3 {
+				line := s.get(unplaced, http.StatusOK, forward)
+				wantReputation(t, line)
+				wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+					none)
+			}
+
+			// A refusal for the verdict makes no ban, and every client had its
+			// verdicts, so no zone was asked.
+			if held := server.Ledger.Snapshot(); tc.action == actionDeny && len(held) != 0 {
+				t.Errorf("bans %+v, want none", held)
+			}
+
+			if queries := server.DNSBL.Queries(dnsblZone); queries != 0 {
+				t.Errorf("%d queries, want none", queries)
+			}
+		})
+	}
+}
+
+func TestDNSBLZonesComeAfterTheBlocklistsAndSkipAllowNets(t *testing.T) {
+	t.Parallel()
+
+	s, server, queue := startWithLookups(t, map[string]string{
+		blocklistURLs: dropURL, dnsblZones: dnsblZone, dnsblResolver: noResolver,
+		reputationAction: actionDeny, allowNets: fromDE,
+	})
+	loadLists(t, server, map[string][]string{dropURL: {fromKP}})
+	loadVerdicts(server, map[string][]string{fromKP: {dnsblZone}, fromDE: {dnsblZone}})
+
+	// The blocklist refuses fromKP before its verdict is looked at, and
+	// fromDE, in SWWAF_ALLOW_NETS, is not checked at all: neither is noted
+	// for the zone, nor alerted, nor asked about.
+	wantReputation(t, s.get(fromKP, http.StatusForbidden, requestlog.ActionDenied),
+		dropURL)
+	wantReputation(t, s.get(fromDE, http.StatusOK, requestlog.ActionForward))
+
+	waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
+	if len(waiting) != 1 || waiting[0].Detail["source"] != dropURL {
+		t.Errorf("alerts waiting %+v, want the blocklist's reputation_hit alone", waiting)
+	}
+
+	if queries := server.DNSBL.Queries(dnsblZone); queries != 0 {
+		t.Errorf("%d queries, want none", queries)
+	}
+}
+
+func TestObserveModeForwardsAClientADNSBLZoneDeniesAndAlertsIt(t *testing.T) {
+	t.Parallel()
+
+	s, server, queue := startWithLookups(t, map[string]string{
+		dnsblZones: dnsblZone, dnsblResolver: noResolver, reputationAction: actionDeny,
+		mode: observe,
+	})
+	loadVerdicts(server, map[string][]string{fromDE: {dnsblZone}})
+
+	line := s.get(fromDE, http.StatusOK, requestlog.ActionForward)
+	wantWouldAction(t, line, requestlog.ActionDenied)
+	wantReputation(t, line, dnsblZone)
+
+	waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
+	if len(waiting) != 1 || waiting[0].Event != alerts.EventReputationHit {
+		t.Errorf("alerts waiting %+v, want a reputation_hit alert", waiting)
+	}
+}
+
+func TestReputationLimitTakesPartInTheLowestPercentageOfEveryLimit(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		blocklistAction, reputationAction string
+		// want is the request's limit_percent and bytes_percent, as
+		// percentText gives them.
+		want string
+	}{
+		{limitHalf, limitQuarter, "25 from " + reputationAction},
+		{limitQuarter, limitHalf, "25 from " + blocklistAction},
+		// The blocklist's, the first of two alike.
+		{limitQuarter, limitQuarter, "25 from " + blocklistAction},
+		{actionLog, limitQuarter, "25 from " + reputationAction},
+		{actionLog, actionLog, none},
+	} {
+		t.Run(tc.blocklistAction+" "+tc.reputationAction, func(t *testing.T) {
+			t.Parallel()
+
+			s, server, _ := startWithLookups(t, map[string]string{
+				blocklistURLs: dropURL, blocklistAction: tc.blocklistAction,
+				dnsblZones: dnsblZone, dnsblResolver: noResolver,
+				reputationAction: tc.reputationAction,
+			})
+			loadLists(t, server, map[string][]string{dropURL: {fromDE}})
+			loadVerdicts(server, map[string][]string{fromDE: {dnsblZone}})
+
+			// Named by the blocklist, then by the zone.
+			line := s.get(fromDE, http.StatusOK, requestlog.ActionForward)
+			wantReputation(t, line, dropURL, dnsblZone)
+			wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+				tc.want)
+			wantPercent(t, "bytes_percent", line.BytesPercent, line.BytesPercentSetting,
+				tc.want)
+		})
+	}
+}
+
+func TestEachZoneThatListsAClientRaisesAnAlertOncePerCooldownAndIsCounted(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	s, clk, server, queue := startWithLookupsAndClock(t, map[string]string{
+		dnsblZones: dnsblZone + "," + otherZone, dnsblResolver: noResolver,
+		reputationAction: actionLog, metricsToken: token,
+	})
+	loadVerdicts(server, map[string][]string{
+		fromDE: {dnsblZone, otherZone}, unplaced: nil,
+	})
+
+	// The second request's alerts are repeats, which the cooldown holds
+	// back.
+	for range 2 {
+		wantReputation(t, s.get(fromDE, http.StatusOK, requestlog.ActionForward),
+			dnsblZone, otherZone)
+	}
+
+	hit := func(zone string) alerts.Alert {
+		return alerts.Alert{
+			Instance: alertInstance,
+			Time:     clk.Now(),
+			Event:    alerts.EventReputationHit,
+			Client:   netip.MustParseAddr(fromDE),
+			Netblock: netip.MustParsePrefix(fromDE + "/32"),
+			ASN:      asnDE,
+			ASName:   asNameDE,
+			Country:  "DE",
+			Reason:   "listed by a DNSBL zone",
+			Detail:   map[string]any{"source": zone},
+		}
+	}
+	wantAlerts(t, queue, hit(dnsblZone), hit(otherZone))
+
+	if queue.Suppressed() != 2 {
+		t.Errorf("%d alerts held back, want the second request's 2", queue.Suppressed())
+	}
+
+	// Each zone's hits, and its queries and their failures, none, since
+	// every client had its verdicts.
+	metrics := s.scrape(unplaced)
+
+	for _, zone := range []string{dnsblZone, otherZone} {
+		labels := `{instance="` + alertInstance + `",source="` + zone + `"}`
+
+		wantMetric(t, metrics, "smallwebwaf_reputation_hits_total"+labels, 2)
+		wantMetric(t, metrics, "smallwebwaf_reputation_queries_total"+labels, 0)
+		wantMetric(t, metrics, "smallwebwaf_reputation_failures_total"+labels, 0)
+	}
+}
+
+func TestZoneKeyIsMaskedInTheLogTheAlertAndTheMetrics(t *testing.T) {
+	t.Parallel()
+
+	const (
+		key    = "abcdefghijklmnopqrstuvwxyz"
+		keyed  = key + ".xbl.dq.spamhaus.net"
+		masked = "********.xbl.dq.spamhaus.net"
+	)
+
+	s, server, queue := startWithLookups(t, map[string]string{
+		dnsblZones: keyed, dnsblResolver: noResolver, reputationAction: actionLog,
+		metricsToken: token,
+	})
+	loadVerdicts(server, map[string][]string{fromDE: {keyed}, unplaced: nil})
+
+	wantReputation(t, s.get(fromDE, http.StatusOK, requestlog.ActionForward), masked)
+
+	waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
+	if len(waiting) != 1 || waiting[0].Detail["source"] != masked {
+		t.Errorf("alerts waiting %+v, want a reputation_hit alert from %s", waiting,
+			masked)
+	}
+
+	metrics := s.scrape(unplaced)
+	wantMetric(t, metrics, `smallwebwaf_reputation_hits_total{instance="`+
+		alertInstance+`",source="`+masked+`"}`, 1)
+
+	for name, shown := range map[string]string{
+		"the log": s.out.text(), "the metrics": metrics,
+	} {
+		if strings.Contains(shown, key) {
+			t.Errorf("%s shows the key:\n%s", name, shown)
+		}
+	}
+}
+
+func TestRequestFromAClientWithoutAVerdictHasTheZoneAskedAboutIt(t *testing.T) {
+	t.Parallel()
+
+	s, server, _ := startWithLookups(t, map[string]string{
+		dnsblZones: dnsblZone + "," + otherZone, dnsblResolver: noResolver,
+	})
+	server.DNSBL.Load([]reputation.Verdict{{
+		Zone: otherZone, Client: netip.MustParseAddr(fromDE), Listed: true,
+		Fetched: verdictsFetched(),
+	}})
+
+	// The verdict of the other zone is used, and dnsbl.example, which has
+	// none, is asked about the client in the background, once: the second
+	// request finds the query under way, or the zone left alone after it
+	// failed, since nothing answers at noResolver.
+	for range 2 {
+		wantReputation(t, s.get(fromDE, http.StatusOK, requestlog.ActionForward), otherZone)
+	}
+
+	if queries := server.DNSBL.Queries(dnsblZone); queries != 1 {
+		t.Errorf("%d queries to %s, want 1", queries, dnsblZone)
+	}
+
+	if queries := server.DNSBL.Queries(otherZone); queries != 0 {
+		t.Errorf("%d queries to %s, want none", queries, otherZone)
+	}
+}
+
+// The AbuseIPDB settings, and accountKey, the key the tests set.
+const (
+	abuseIPDBKey = "SWWAF_ABUSEIPDB_KEY"
+	accountKey   = "abuseipdb-key-0123456789abcdef"
+)
+
+// abuseipdb is how the request log, the alerts and the metrics name
+// AbuseIPDB.
+const abuseipdb = reputation.AbuseIPDBSource
+
+// abuseIPDBURL is where newProxy has clients checked with AbuseIPDB: at
+// abuseIPDBStandIn, which TestMain registers with Go's default transport,
+// through which AbuseIPDB is asked.
+const abuseIPDBURL = "abuseipdb://stand-in/api/v2/check"
+
+// abuseIPDBStandIn is a stand-in for AbuseIPDB that gives every client the
+// score 100, at once and without the network.
+type abuseIPDBStandIn struct{}
+
+// RoundTrip answers req with the score 100.
+func (abuseIPDBStandIn) RoundTrip(req *http.Request) (*http.Response, error) {
+	return &http.Response{
+		StatusCode: http.StatusOK,
+		Status:     "200 OK",
+		Header:     http.Header{},
+		Body:       io.NopCloser(strings.NewReader(`{"data":{"abuseConfidenceScore":100}}`)),
+		Request:    req,
+	}, nil
+}
+
+func TestOnlyAClientThatHasCommittedAnOffenceIsCheckedWithAbuseIPDB(t *testing.T) {
+	t.Parallel()
+
+	forward := requestlog.ActionForward
+
+	s, clk, server, _ := startWithLookupsAndClock(t, map[string]string{
+		abuseIPDBKey: accountKey, rateLimitPerMinute: "2", reputationAction: actionLog,
+	})
+
+	// Neither fromDE, until it breaks a rate limit, nor fromKP, which never
+	// does, is checked, nor fromDE under the ban that makes.
+	s.get(fromDE, http.StatusOK, forward)
+	s.get(fromDE, http.StatusOK, forward)
+	s.get(fromKP, http.StatusOK, forward)
+	s.get(fromDE, http.StatusForbidden, requestlog.ActionRateLimited)
+	s.get(fromDE, http.StatusForbidden, requestlog.ActionBanned)
+	wantAbuseIPDBChecks(t, server, 0)
+
+	// Once the ban has ended, fromDE's first request has it checked in the
+	// background, and goes on without its score, which its next request
+	// finds.
+	clk.advance(time.Hour)
+	wantReputation(t, s.get(fromDE, http.StatusOK, forward))
+	wantAbuseIPDBChecks(t, server, 1)
+	waitUntil(func() bool { return len(server.AbuseIPDB.Snapshot().Scores) == 1 })
+	wantReputation(t, s.get(fromDE, http.StatusOK, forward), abuseipdb)
+
+	s.get(fromKP, http.StatusOK, forward)
+	wantAbuseIPDBChecks(t, server, 1)
+}
+
+func TestIPv6ClientCostsOneAbuseIPDBCheckWhicheverOfItsAddressesSends(t *testing.T) {
+	t.Parallel()
+
+	forward := requestlog.ActionForward
+
+	// 15 addresses of 2001:db8:1:2::/64, one client, each in a part of it
+	// of its own.
+	var addresses []string
+	for i := 1; i < 16; i++ {
+		addresses = append(addresses, fmt.Sprintf("2001:db8:1:2:%x::9", i<<12))
+	}
+
+	s, clk, server := startWithClock(t, "", map[string]string{
+		abuseIPDBKey: accountKey, reputationAction: actionLog,
+		rateLimitPerMinute: strconv.Itoa(len(addresses)),
+	})
+
+	// The client breaks the rate limit from its first address, which bans
+	// it for an hour.
+	for range addresses {
+		s.get(addresses[0], http.StatusOK, forward)
+	}
+
+	s.get(addresses[0], http.StatusForbidden, requestlog.ActionRateLimited)
+	clk.advance(time.Hour)
+
+	// Once the ban has ended, which set its counters back to zero, a
+	// request from each of its addresses has it checked once.
+	for _, address := range addresses {
+		s.get(address, http.StatusOK, forward)
+	}
+
+	wantAbuseIPDBChecks(t, server, 1)
+}
+
+// probePath is the path the ban rule of testRules, probe, matches.
+const probePath = "/.env"
+
+func TestClientARuleRefusedIsCheckedWithAbuseIPDBAtItsNextRequest(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name string
+		// path is what the client asks for, status and action what that
+		// request is answered and logged with, and want the offences its
+		// history then counts.
+		path   string
+		status int
+		action string
+		want   ratelimit.Offences
+	}{
+		{
+			"a block rule", "/blocked", http.StatusForbidden, requestlog.ActionRuleBlocked,
+			ratelimit.Offences{RuleBlocked: 1},
+		},
+		{
+			"a ban rule", probePath, http.StatusForbidden, requestlog.ActionBanned,
+			ratelimit.Offences{Attack: 1},
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			s, clk, server := startWithClock(t, "", map[string]string{
+				abuseIPDBKey: accountKey, reputationAction: actionLog,
+				rulesDir: writeRules(t, testRules), attackBanDuration: "1h",
+			})
+
+			s.request(client, tc.path, tc.status, tc.action)
+			wantAbuseIPDBChecks(t, server, 0)
+
+			if got := historyOf(t, server, client).Offences; got != tc.want {
+				t.Errorf("history counts the offences %+v, want %+v", got, tc.want)
+			}
+
+			// Its next request, once a ban rule's ban has ended, has it
+			// checked.
+			clk.advance(time.Hour)
+			s.get(client, http.StatusOK, requestlog.ActionForward)
+			wantAbuseIPDBChecks(t, server, 1)
+		})
+	}
+}
+
+func TestEachReputationActionForAClientAbuseIPDBScoresAtOrOverTheMinimum(t *testing.T) {
+	t.Parallel()
+
+	forward, denied := requestlog.ActionForward, requestlog.ActionDenied
+
+	for _, tc := range []struct {
+		action string
+		// statuses and actions are those of fromDE's three requests, and
+		// percent their limit_percent, as percentText gives it.
+		statuses []int
+		actions  []string
+		percent  string
+	}{
+		{
+			actionDeny, []int{http.StatusForbidden, http.StatusForbidden, http.StatusForbidden},
+			[]string{denied, denied, denied}, none,
+		},
+		{
+			// Half of 4 requests a minute: the third breaks the limit.
+			limitHalf, []int{http.StatusOK, http.StatusOK, http.StatusForbidden},
+			[]string{forward, forward, requestlog.ActionRateLimited},
+			"50 from " + reputationAction,
+		},
+		{
+			actionLog, []int{http.StatusOK, http.StatusOK, http.StatusOK},
+			[]string{forward, forward, forward}, none,
+		},
+	} {
+		t.Run(tc.action, func(t *testing.T) {
+			t.Parallel()
+
+			s, server, _ := startWithLookups(t, map[string]string{
+				rateLimitPerMinute: fourAMinute, abuseIPDBKey: accountKey,
+				reputationAction: tc.action,
+			})
+			// At SWWAF_ABUSEIPDB_MIN_SCORE, 75 by default, and just under it.
+			loadScores(server, map[string]int64{fromDE: 75, fromKP: 74})
+
+			for i := range 3 {
+				line := s.get(fromDE, tc.statuses[i], tc.actions[i])
+				wantReputation(t, line, abuseipdb)
+				wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+					tc.percent)
+
+				// A request refused for the score is not counted.
+				counted := line.fields["counts"] != nil
+				if counted != (tc.actions[i] != denied) {
+					t.Errorf("request counted %t, logged %s", counted, tc.actions[i])
+				}
+			}
+
+			// fromKP's score is no hit, and it has the whole limit.
+			for range 3 {
+				line := s.get(fromKP, http.StatusOK, forward)
+				wantReputation(t, line)
+				wantPercent(t, "limit_percent", line.LimitPercent, line.LimitPercentSetting,
+					none)
+			}
+
+			// A refusal for the score makes no ban.
+			if held := server.Ledger.Snapshot(); tc.action == actionDeny && len(held) != 0 {
+				t.Errorf("bans %+v, want none", held)
+			}
+		})
+	}
+}
+
+func TestAbuseIPDBHitRaisesAnAlertWithTheScoreOncePerCooldownAndIsCounted(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	s, server, queue := startWithLookups(t, map[string]string{
+		abuseIPDBKey: accountKey, reputationAction: actionLog, metricsToken: token,
+	})
+	loadScores(server, map[string]int64{fromDE: 90})
+
+	// The second request's alert is a repeat, which the cooldown holds back.
+	for range 2 {
+		wantReputation(t, s.get(fromDE, http.StatusOK, requestlog.ActionForward),
+			abuseipdb)
+	}
+
+	// The alert is made as a DNSBL zone's is, with the score besides.
+	waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
+	if len(waiting) != 1 || waiting[0].Event != alerts.EventReputationHit ||
+		waiting[0].Reason != "scored by AbuseIPDB at or over SWWAF_ABUSEIPDB_MIN_SCORE" ||
+		waiting[0].Detail["source"] != abuseipdb || waiting[0].Detail["score"] != int64(90) ||
+		queue.Suppressed() != 1 {
+		t.Errorf("alerts waiting %+v, %d held back, want AbuseIPDB's reputation_hit "+
+			"with the score 90, and 1", waiting, queue.Suppressed())
+	}
+
+	// The hits, and the checks, none, since no client committed an
+	// offence, so that the whole budget is left.
+	metrics := s.scrape(unplaced)
+	labels := `{instance="` + alertInstance + `",source="` + abuseipdb + `"}`
+
+	wantMetric(t, metrics, "smallwebwaf_reputation_hits_total"+labels, 2)
+	wantMetric(t, metrics, "smallwebwaf_reputation_queries_total"+labels, 0)
+	wantMetric(t, metrics, "smallwebwaf_reputation_failures_total"+labels, 0)
+	wantMetric(t, metrics, "smallwebwaf_reputation_daily_budget_remaining"+labels, 900)
+}
+
+func TestWithoutAnAbuseIPDBKeyNoClientIsCheckedNorAScoreUsed(t *testing.T) {
+	t.Parallel()
+
+	forward := requestlog.ActionForward
+
+	s, clk, server, _ := startWithLookupsAndClock(t, map[string]string{
+		rateLimitPerMinute: "1", metricsToken: token,
+	})
+	loadScores(server, map[string]int64{fromDE: 100})
+
+	// fromDE's score is not used, and once it has committed an offence it
+	// is not checked either.
+	wantReputation(t, s.get(fromDE, http.StatusOK, forward))
+	s.get(fromDE, http.StatusForbidden, requestlog.ActionRateLimited)
+	clk.advance(time.Hour)
+	wantReputation(t, s.get(fromDE, http.StatusOK, forward))
+	wantAbuseIPDBChecks(t, server, 0)
+
+	wantNoSeries(t, s.scrape(unplaced), `smallwebwaf_reputation_daily_budget_remaining{`+
+		`instance="`+alertInstance+`",source="`+abuseipdb+`"}`)
+}
+
+// listsFetched is when loadLists has the copies fetched.
+func listsFetched() time.Time {
+	return time.Date(2026, 10, 5, 0, 0, 0, 0, time.UTC)
+}
+
+// verdictsFetched is when loadVerdicts has the verdicts fetched: half a
+// day before the time the tests' clock is set to, so that they are in use
+// until half a day later.
+func verdictsFetched() time.Time {
+	return time.Date(2026, 10, 5, 12, 0, 0, 0, time.UTC)
+}
+
+// loadVerdicts puts into server's DNSBL, for each client listedBy names,
+// a verdict of each zone SWWAF_DNSBL_ZONES names, fetched at
+// verdictsFetched, as reputation.json would at start: one that lists the
+// client from each zone listedBy gives for it, and one that does not from
+// each other zone.
+func loadVerdicts(server *proxy.Server, listedBy map[string][]string) {
+	verdicts := make([]reputation.Verdict, 0, len(listedBy)*len(server.DNSBL.Zones()))
+
+	for client, zones := range listedBy {
+		for _, zone := range server.DNSBL.Zones() {
+			verdicts = append(verdicts, reputation.Verdict{
+				Zone: zone, Client: netip.MustParseAddr(client),
+				Listed: slices.Contains(zones, zone), Fetched: verdictsFetched(),
+			})
+		}
+	}
+
+	server.DNSBL.Load(verdicts)
+}
+
+// loadScores puts into server's AbuseIPDB the score scores gives each
+// client, an IPv4 address, fetched at verdictsFetched, as reputation.json
+// would at start.
+func loadScores(server *proxy.Server, scores map[string]int64) {
+	kept := make([]reputation.Score, 0, len(scores))
+	for client, score := range scores {
+		kept = append(kept, reputation.Score{
+			Client: netip.MustParsePrefix(client + "/32"), Score: score,
+			Fetched: verdictsFetched(),
+		})
+	}
+
+	server.AbuseIPDB.Load(reputation.Checks{Scores: kept})
+}
+
+// wantAbuseIPDBChecks checks how many clients server has checked with
+// AbuseIPDB.
+func wantAbuseIPDBChecks(t *testing.T, server *proxy.Server, want int) {
+	t.Helper()
+
+	if got := server.AbuseIPDB.Checked(); got != want {
+		t.Errorf("%d clients checked with AbuseIPDB, want %d", got, want)
+	}
+}
+
+// loadLists puts copies of lists into server's lists, by URL, each with
+// its lines, fetched at listsFetched, as reputation.json would at start.
+func loadLists(t *testing.T, server *proxy.Server, copies map[string][]string) {
+	t.Helper()
+
+	lists := make([]reputation.List, 0, len(copies))
+	for listURL, lines := range copies {
+		lists = append(lists, reputation.List{
+			URL: listURL, Fetched: listsFetched(), Lines: lines,
+		})
+	}
+
+	err := server.Lists.Load(lists)
+	if err != nil {
+		t.Fatalf("load the lists: %v", err)
+	}
+}
+
+// wantReputation checks the URLs of the blocklists the log line names in
+// its reputation.
+func wantReputation(t *testing.T, line logLine, want ...string) {
+	t.Helper()
+
+	if !slices.Equal(line.Reputation, want) {
+		t.Errorf("log line has reputation %v, want %v", line.Reputation, want)
+	}
+}

internal/proxy/request.go

@@ -3,6 +3,7 @@ package proxy
 import (
 	"context"
 	"errors"
+	"io"
 	"net/http"
 	"net/http/httptrace"
 	"net/http/httputil"
@@ -15,6 +16,8 @@ import (
 	"sync/atomic"
 	"time"
 
+	"sneak.berlin/go/smallwebwaf/internal/anomaly"
+	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/lookup"
 	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
@@ -54,7 +57,21 @@ type request struct {
 	// what the lookup gave then, the zero Answer while GeoJS had given none.
 	lookedUp     bool
 	lookupAnswer lookup.Answer
-	start        time.Time
+	// counted is true for a request the rate limits counted, whose bytes
+	// the byte limits count once it has ended. limitPercent and
+	// bytesPercent are then its client's limit percentages for the rate
+	// limits and for the byte limits.
+	counted                    bool
+	limitPercent, bytesPercent percentage
+	// attack is true for a request that matched a ban rule, and
+	// ruleBlocked for one a block rule refused, each an offence its
+	// client's history counts.
+	attack, ruleBlocked bool
+	// blocklisted is true once a blocklist is found to list the client,
+	// dnsblListed once a DNSBL zone's verdict is, and abuseIPDBHit once
+	// AbuseIPDB's score of it is a hit.
+	blocklisted, dnsblListed, abuseIPDBHit bool
+	start                                  time.Time
 	// checked is when the checks were done, and upstreamStart when the
 	// request was handed to the app.
 	checked       time.Time
@@ -65,6 +82,9 @@ type request struct {
 	refused atomic.Pointer[refusal]
 	// complete is true once the app's whole answer has been passed on.
 	complete bool
+	// upgraded is the connection to the app once the app has switched
+	// protocols, as for a WebSocket, and nil otherwise.
+	upgraded *upgradedConn
 
 	// mu guards what follows. The timeouts run on goroutines of their
 	// own, and the transport starts and stops them, and notes the times
@@ -201,12 +221,15 @@ func (rq *request) check(ctx context.Context) *refusal {
 // client in SWWAF_ALLOW_NETS skips them, and is not looked up. For any
 // other client, SWWAF_DENY_NETS comes first, then a ban on its netblock,
 // so that a client either refuses is not looked up, then the lookup of
-// its AS number and country, and then the country lists; a request any of
-// them refuses is not counted for the rate limits. Then come the rate
-// limits, unless the client is in SWWAF_RATE_LIMIT_EXEMPT_NETS or the
+// its AS number and country, then the country lists, then the blocklists,
+// then the DNSBL zones' verdicts, and then AbuseIPDB's score; a request
+// any of them refuses is not counted for the rate limits. Then come the
+// rate limits, unless the client is in SWWAF_RATE_LIMIT_EXEMPT_NETS or the
 // request's path is exempt under SWWAF_RATE_LIMIT_EXEMPT_PATHS, so that
-// every other request is counted, and last the rule files. ctx is the
-// request's own context.
+// every other request is counted, each of them by the client's limit
+// percentages, and last the rule files. A request exempt from the rate
+// limits is exempt from the byte limits too. ctx is the request's own
+// context.
 func (rq *request) checkClient(ctx context.Context) string {
 	cfg := rq.h.config
 	if isInside(rq.client, cfg.AllowNets) {
@@ -229,9 +252,23 @@ func (rq *request) checkClient(ctx context.Context) string {
 		return requestlog.ActionCountryDenied
 	}
 
-	exempt := isInside(rq.client, cfg.RateLimitExemptNets) ||
-		pathExempt(rq.in.URL, cfg.RateLimitExemptPaths)
-	if !exempt && rq.limitBroken(now) {
+	if rq.blocklistDenied() {
+		return requestlog.ActionDenied
+	}
+
+	if rq.dnsblDenied(ctx) || rq.abuseIPDBDenied(ctx) {
+		return requestlog.ActionDenied
+	}
+
+	rq.counted = !isInside(rq.client, cfg.RateLimitExemptNets) &&
+		!pathExempt(rq.in.URL, cfg.RateLimitExemptPaths)
+	if rq.counted {
+		rq.limitPercent, rq.bytesPercent = rq.limitPercentages()
+		rq.line.LimitPercent, rq.line.LimitPercentSetting = rq.limitPercent.logged()
+		rq.line.BytesPercent, rq.line.BytesPercentSetting = rq.bytesPercent.logged()
+	}
+
+	if rq.counted && rq.limitBroken(now) {
 		return requestlog.ActionRateLimited
 	}
 
@@ -324,11 +361,18 @@ func (rq *request) modifyResponse(res *http.Response) error {
 	if res.StatusCode == http.StatusSwitchingProtocols {
 		// An upgraded connection, such as a WebSocket, is not cut by the
 		// timeouts. ReverseProxy writes this answer straight to the
-		// connection it takes over, not through rq.out.
+		// connection it takes over, not through rq.out, and then copies
+		// what passes each way through res.Body, the connection to the app.
 		rq.stopTimers()
 		rq.out.status = res.StatusCode
 		rq.line.Websocket = true
 
+		conn, ok := res.Body.(io.ReadWriteCloser)
+		if ok {
+			rq.upgraded = &upgradedConn{ReadWriteCloser: conn}
+			res.Body = rq.upgraded
+		}
+
 		return nil
 	}
 
@@ -431,10 +475,7 @@ func (rq *request) finish() {
 	line.ResponseContentType = header.Get("Content-Type")
 	line.CacheControl = header.Get("Cache-Control")
 	line.Location = header.Get("Location")
-
-	if rq.body != nil {
-		line.RequestBytes = rq.body.bytes.Load()
-	}
+	line.RequestBytes = rq.requestBytes()
 
 	// limit is the setting whose size or time limit the request passed.
 	var limit string
@@ -491,46 +532,87 @@ func timing(start, end time.Time) *float64 {
 }
 
 // addToHistory adds the request, which has ended, to its client's
-// history, and then, for a client that was looked up, the lookup
-// database's answer about it, or the answer from GeoJS kept about it, to
-// that history and to the notes of the bans on its netblock: an answer
-// may have come before either was there, and one from GeoJS that comes
-// later is added when it comes.
+// history, and then the lookup's answer about the client, as
+// answerAtTheEnd gives it, to that history and to the notes of the bans
+// on its netblock: an answer may have come before either was there, and
+// one from GeoJS that comes later is added when it comes.
 func (rq *request) addToHistory() {
-	var requestBytes int64
-	if rq.body != nil {
-		requestBytes = rq.body.bytes.Load()
-	}
-
 	forwarded := !rq.upstreamStart.IsZero()
-	group := clientGroup(rq.client)
 
-	rq.h.limiter.AddToHistory(group, rq.h.now(), ratelimit.Request{
+	rq.h.limiter.AddToHistory(clientGroup(rq.client), rq.h.now(), ratelimit.Request{
 		Forwarded:     forwarded,
 		Refused:       !forwarded && rq.refused.Load() != nil,
 		Status:        rq.out.status,
-		RequestBytes:  requestBytes,
+		RequestBytes:  rq.requestBytes(),
 		ResponseBytes: rq.out.bytes,
 		BrokeLimit:    rq.line.Offence == requestlog.OffenceLimit,
+		Attack:        rq.attack,
+		RuleBlocked:   rq.ruleBlocked,
 	})
 
-	if !rq.lookedUp {
-		return
-	}
-
-	// The lookup database's answer was there at once.
-	if rq.h.config.LookupSource == "file" {
-		rq.h.addLookup(rq.lookupAnswer)
-
-		return
-	}
-
-	answer, kept := rq.h.geojs.Kept(group)
-	if kept {
+	answer, found := rq.answerAtTheEnd()
+	if found {
 		rq.h.addLookup(answer)
 	}
 }
 
+// countAnomalies counts the request, which has ended, and its bytes, as
+// countedBytes gives them, for the anomaly thresholds, whatever was done
+// with it: a request refused, one from a client in SWWAF_ALLOW_NETS or
+// SWWAF_RATE_LIMIT_EXEMPT_NETS, and one for a path in
+// SWWAF_RATE_LIMIT_EXEMPT_PATHS are counted too. It is counted for its
+// client's AS number when answerAtTheEnd gives one. With every anomaly
+// threshold off, the default, it does nothing.
+func (rq *request) countAnomalies() {
+	if !anomalyThresholdsSet(rq.h.config) {
+		return
+	}
+
+	answer, _ := rq.answerAtTheEnd()
+
+	rq.h.anomalies.Count(rq.h.now(), anomaly.Request{
+		Client:      rq.client,
+		ClientGroup: clientGroup(rq.client),
+		ASN:         answer.ASN,
+		ASName:      answer.ASName,
+		Country:     answer.Country,
+		Bytes:       rq.countedBytes(),
+	})
+}
+
+// anomalyThresholdsSet reports whether any anomaly threshold is set.
+func anomalyThresholdsSet(cfg *config.Config) bool {
+	off := anomaly.Thresholds{}
+
+	return cfg.AnomalyClient != off || cfg.AnomalyNet != off || cfg.AnomalyASN != off ||
+		cfg.AnomalyTotal != off || cfg.AnomalyWatch != off
+}
+
+// answerAtTheEnd returns, for a client that was looked up, the lookup's
+// answer about it as the request ends, and whether there is one: the
+// lookup database's, which was there at once, or the one GeoJS has given
+// by then, which a request does not wait for unless a setting needs it.
+func (rq *request) answerAtTheEnd() (lookup.Answer, bool) {
+	if !rq.lookedUp {
+		return lookup.Answer{}, false
+	}
+
+	if rq.h.config.LookupSource == "file" {
+		return rq.lookupAnswer, true
+	}
+
+	return rq.h.geojs.Kept(clientGroup(rq.client))
+}
+
+// requestBytes is how many bytes of the request's body have been read.
+func (rq *request) requestBytes() int64 {
+	if rq.body == nil {
+		return 0
+	}
+
+	return rq.body.bytes.Load()
+}
+
 // clientRequestDeadline is when the client must have sent its whole
 // request, or zero when SWWAF_CLIENT_REQUEST_TIMEOUT is off.
 func (rq *request) clientRequestDeadline() time.Time {

internal/proxy/requestlog_test.go

@@ -119,7 +119,10 @@ func wantFullLine(t *testing.T, line logLine) {
 		ResponseContentType: "text/html", UpstreamStatus: http.StatusFound,
 		CacheControl: "no-store", Location: "/elsewhere",
 		Action: requestlog.ActionForward,
-		Counts: ratelimit.Counts{Minute: 1, Hour: 1, Day: 1},
+		// Its 3 bytes in and 5 out, each way counted by default.
+		Counts: ratelimit.Counts{
+			Minute: 1, Hour: 1, Day: 1, MinuteBytes: 8, HourBytes: 8, DayBytes: 8,
+		},
 	})
 	if !reflect.DeepEqual(line.Line, want) {
 		t.Errorf("log line\n%+v\nwant\n%+v", line.Line, want)

internal/proxy/rules.go

@@ -12,7 +12,8 @@ import (
 // action of the rule that refuses it, ActionRuleBlocked for a block rule
 // and ActionBanned for a ban rule, or "" when none does. A ban rule bans
 // the client's netblock for a clear sign of attack, or in observe mode
-// raises the alert for the ban it would have made.
+// raises the alert for the ban it would have made. Either rule's match
+// is noted as an offence, for the client's history.
 func (rq *request) checkRules(now time.Time) string {
 	matched := rq.h.rules.Match(rq.in)
 
@@ -28,8 +29,11 @@ func (rq *request) checkRules(now time.Time) string {
 	// Only the last rule matched can refuse the request.
 	switch last := matched[len(matched)-1]; last.Action {
 	case rules.ActionBlock:
+		rq.ruleBlocked = true
+
 		return requestlog.ActionRuleBlocked
 	case rules.ActionBan:
+		rq.attack = true
 		rq.banForAttack(now, last)
 
 		return requestlog.ActionBanned

internal/ratelimit/ratelimit.go

@@ -1,9 +1,9 @@
 // Package ratelimit keeps the table of clients: each client's requests
-// counted over a minute, an hour and a day, as the "Counting method"
-// section of SPEC.md describes, which tell when a request takes the client
-// over a rate limit, and each client's history since it was first seen.
-// At most 20,000 clients are kept, in memory, and written to clients.json
-// and read from it by the state package.
+// and bytes counted over a minute, an hour and a day, as the "Counting
+// method" section of SPEC.md describes, which tell when a request takes
+// the client over a rate limit or a byte limit, and each client's history
+// since it was first seen. At most 20,000 clients are kept, in memory, and
+// written to clients.json and read from it by the state package.
 package ratelimit
 
 import (
@@ -23,19 +23,30 @@ const maxClients = 20000
 
 const day = 24 * time.Hour
 
+// The kinds of limits, as the metrics name them.
+const (
+	// KindRequests is a rate limit, on a client's requests.
+	KindRequests = "requests"
+	// KindBytes is a byte limit, on a client's bytes.
+	KindBytes = "bytes"
+)
+
 // Limits are the most requests a client may make in a minute, an hour and
-// a day. Zero is no limit.
+// a day, and the most bytes. Zero is no limit.
 type Limits struct {
-	PerMinute int64
-	PerHour   int64
-	PerDay    int64
+	PerMinute      int64
+	PerHour        int64
+	PerDay         int64
+	BytesPerMinute int64
+	BytesPerHour   int64
+	BytesPerDay    int64
 }
 
-// Limiter counts each client's requests against the limits, and keeps
-// its history. It is safe for concurrent use.
+// Limiter counts each client's requests and bytes against the limits, and
+// keeps its history. It is safe for concurrent use.
 type Limiter struct {
 	// windows are the minute, the hour and the day, in the order of
-	// Client.buckets.
+	// Client.buckets and Client.byteBuckets.
 	windows [3]window
 
 	mu      sync.Mutex
@@ -43,17 +54,23 @@ type Limiter struct {
 }
 
 // Client is a client in the table, as clients.json holds it: its buckets
-// in each window, and its history.
+// of requests and of bytes in each window, and its history.
+//
+//nolint:tagliatelle // the state files use snake_case, as the request log does
 type Client struct {
-	Client  netip.Prefix `json:"client"`
-	Minute  Buckets      `json:"minute"`
-	Hour    Buckets      `json:"hour"`
-	Day     Buckets      `json:"day"`
-	History History      `json:"history"`
+	Client      netip.Prefix `json:"client"`
+	Minute      Buckets      `json:"minute"`
+	Hour        Buckets      `json:"hour"`
+	Day         Buckets      `json:"day"`
+	MinuteBytes Buckets      `json:"minute_bytes"`
+	HourBytes   Buckets      `json:"hour_bytes"`
+	DayBytes    Buckets      `json:"day_bytes"`
+	History     History      `json:"history"`
 }
 
-// Buckets are a client's two buckets in one window: the requests in the
-// bucket under way, which began at Start, and in the bucket before it.
+// Buckets are a client's two buckets in one window: the requests, or the
+// bytes, in the bucket under way, which began at Start, and in the bucket
+// before it.
 type Buckets struct {
 	Start    time.Time `json:"start"`
 	Current  int64     `json:"current"`
@@ -100,9 +117,15 @@ type Responses struct {
 }
 
 // Offences are a client's offences, by kind.
+//
+//nolint:tagliatelle // the state files use snake_case, as the request log does
 type Offences struct {
-	// Limit is its requests that broke a rate limit.
-	Limit int64 `json:"limit"`
+	// Limit is its requests that broke a rate limit or a byte limit,
+	// Attack those that matched a ban rule, a clear sign of attack, and
+	// RuleBlocked those a block rule refused.
+	Limit       int64 `json:"limit"`
+	Attack      int64 `json:"attack"`
+	RuleBlocked int64 `json:"rule_blocked"`
 }
 
 // Request is what a client's history keeps of one of its requests.
@@ -119,8 +142,12 @@ type Request struct {
 	// and of its response.
 	RequestBytes  int64
 	ResponseBytes int64
-	// BrokeLimit is true for a request that broke a rate limit.
-	BrokeLimit bool
+	// BrokeLimit is true for a request that broke a rate limit or a byte
+	// limit, Attack for one that matched a ban rule, and RuleBlocked for
+	// one a block rule refused.
+	BrokeLimit  bool
+	Attack      bool
+	RuleBlocked bool
 }
 
 // New returns a Limiter for limits, with no client counted yet.
@@ -132,62 +159,74 @@ func New(limits Limits) *Limiter {
 
 	return &Limiter{
 		windows: [3]window{
-			{name: "minute", length: time.Minute, limit: limits.PerMinute},
-			{name: "hour", length: time.Hour, limit: limits.PerHour},
-			{name: "day", length: day, limit: limits.PerDay},
+			{
+				name: "minute", length: time.Minute,
+				limit: limits.PerMinute, byteLimit: limits.BytesPerMinute,
+			},
+			{
+				name: "hour", length: time.Hour,
+				limit: limits.PerHour, byteLimit: limits.BytesPerHour,
+			},
+			{
+				name: "day", length: day,
+				limit: limits.PerDay, byteLimit: limits.BytesPerDay,
+			},
 		},
 		clients: clients,
 	}
 }
 
-// Hit is a request that takes a client over a rate limit.
+// Hit is a request that takes a client over a rate limit, or whose bytes
+// take it over a byte limit.
 type Hit struct {
+	// Kind is KindRequests for a rate limit, KindBytes for a byte limit.
+	Kind string
 	// Window is "minute", "hour" or "day".
 	Window string
-	// Limit is the window's limit.
+	// Limit is the window's limit, as the client's percentage of it.
 	Limit int64
-	// Requests is the client's requests counted in the window, this one
-	// included.
-	Requests float64
+	// Count is the client's requests, or bytes, counted in the window,
+	// this request's included.
+	Count float64
 }
 
-// Counts are a client's requests in the minute, the hour and the day that
-// end at a request, that request included.
+// Counts are a client's requests and bytes in the minute, the hour and
+// the day that end at a request, that request's included.
+//
+//nolint:tagliatelle // SPEC.md's request log names its fields in snake_case
 type Counts struct {
-	Minute float64 `json:"minute"`
-	Hour   float64 `json:"hour"`
-	Day    float64 `json:"day"`
+	Minute      float64 `json:"minute"`
+	Hour        float64 `json:"hour"`
+	Day         float64 `json:"day"`
+	MinuteBytes float64 `json:"minute_bytes"`
+	HourBytes   float64 `json:"hour_bytes"`
+	DayBytes    float64 `json:"day_bytes"`
 }
 
 // Count counts a request from client at now, in every window, whether or
-// not it is refused, and returns the client's requests in each window. It
-// reports whether the request takes the client over a limit, and the
-// window whose limit it goes over, the shortest if it is over several.
-func (l *Limiter) Count(client netip.Prefix, now time.Time) (Counts, Hit, bool) {
-	l.mu.Lock()
-	defer l.mu.Unlock()
-
-	var (
-		requests [3]float64
-		hit      Hit
-	)
-
-	for i, b := range l.get(client).buckets() {
-		w := l.windows[i]
-
-		requests[i] = b.add(now, w.length)
-		if hit.Window == "" && w.limit > 0 && requests[i] > float64(w.limit) {
-			hit = Hit{Window: w.name, Limit: w.limit, Requests: requests[i]}
-		}
-	}
-
-	counts := Counts{Minute: requests[0], Hour: requests[1], Day: requests[2]}
-
-	return counts, hit, hit.Window != ""
+// not it is refused, and returns the client's counts in each window. It
+// reports whether the request takes the client over a rate limit, of
+// which the client gets the percentage percent, rounded down, and the hit:
+// the window whose limit it goes over, the shortest if it is over
+// several. A limit that is off stays off.
+func (l *Limiter) Count(
+	client netip.Prefix, now time.Time, percent int64,
+) (Counts, Hit, bool) {
+	return l.count(client, now, 1, 0, percent)
 }
 
-// Reset sets client's counts in every window back to zero. Its history
-// keeps its totals.
+// CountBytes counts bytes, those of a request from client that has ended,
+// at now, in every window, and returns the client's counts in each window.
+// It reports whether the bytes take the client over a byte limit, of which
+// the client gets the percentage percent, and the hit, as Count does.
+func (l *Limiter) CountBytes(
+	client netip.Prefix, now time.Time, bytes, percent int64,
+) (Counts, Hit, bool) {
+	return l.count(client, now, 0, bytes, percent)
+}
+
+// Reset sets client's counts of requests and of bytes in every window
+// back to zero. Its history keeps its totals.
 func (l *Limiter) Reset(client netip.Prefix) {
 	l.mu.Lock()
 	defer l.mu.Unlock()
@@ -195,6 +234,7 @@ func (l *Limiter) Reset(client netip.Prefix) {
 	c, seen := l.clients.Peek(client)
 	if seen {
 		c.Minute, c.Hour, c.Day = Buckets{}, Buckets{}, Buckets{}
+		c.MinuteBytes, c.HourBytes, c.DayBytes = Buckets{}, Buckets{}, Buckets{}
 	}
 }
 
@@ -227,6 +267,14 @@ func (l *Limiter) AddToHistory(client netip.Prefix, now time.Time, r Request) {
 	if r.BrokeLimit {
 		h.Offences.Limit++
 	}
+
+	if r.Attack {
+		h.Offences.Attack++
+	}
+
+	if r.RuleBlocked {
+		h.Offences.RuleBlocked++
+	}
 }
 
 // AddLookup gives client's history its AS number, AS name and country, as
@@ -328,12 +376,11 @@ func (l *Limiter) Load(clients []Client, now time.Time) {
 	l.clients.Purge()
 
 	for _, c := range clients {
-		for i, b := range c.buckets() {
-			// The window that ends at now covers neither bucket once it
-			// begins after the bucket under way has ended.
-			length := l.windows[i].length
-			if !now.Add(-length).Before(b.Start.Add(length)) {
-				*b = Buckets{}
+		for i, w := range l.windows {
+			for _, b := range []*Buckets{c.buckets()[i], c.byteBuckets()[i]} {
+				if b.Passed(now, w.length) {
+					*b = Buckets{}
+				}
 			}
 		}
 
@@ -341,6 +388,51 @@ func (l *Limiter) Load(clients []Client, now time.Time) {
 	}
 }
 
+// count adds requests and bytes from client at now to its buckets in
+// every window, and returns its counts. A limit is broken only by what is
+// added to it, so that a request whose bytes are counted after another of
+// the client's requests broke a rate limit does not break it too. The
+// client gets the percentage percent of each limit.
+func (l *Limiter) count(
+	client netip.Prefix, now time.Time, requests, bytes, percent int64,
+) (Counts, Hit, bool) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	c := l.get(client)
+	requestBuckets, byteBuckets := c.buckets(), c.byteBuckets()
+
+	var (
+		requestCounts, byteCounts [3]float64
+		hit                       Hit
+	)
+
+	for i, w := range l.windows {
+		requestCounts[i] = requestBuckets[i].Add(now, w.length, requests)
+		byteCounts[i] = byteBuckets[i].Add(now, w.length, bytes)
+		limit, byteLimit := percentOf(w.limit, percent), percentOf(w.byteLimit, percent)
+
+		switch {
+		case hit.Window != "":
+		case requests > 0 && w.limit > 0 && requestCounts[i] > float64(limit):
+			hit = Hit{
+				Kind: KindRequests, Window: w.name, Limit: limit, Count: requestCounts[i],
+			}
+		case bytes > 0 && w.byteLimit > 0 && byteCounts[i] > float64(byteLimit):
+			hit = Hit{
+				Kind: KindBytes, Window: w.name, Limit: byteLimit, Count: byteCounts[i],
+			}
+		}
+	}
+
+	counts := Counts{
+		Minute: requestCounts[0], Hour: requestCounts[1], Day: requestCounts[2],
+		MinuteBytes: byteCounts[0], HourBytes: byteCounts[1], DayBytes: byteCounts[2],
+	}
+
+	return counts, hit, hit.Window != ""
+}
+
 // get returns client's entry in the table, a new one if it has none, and
 // makes it the most recently seen.
 func (l *Limiter) get(client netip.Prefix) *Client {
@@ -353,30 +445,48 @@ func (l *Limiter) get(client netip.Prefix) *Client {
 	return c
 }
 
-// buckets returns c's buckets in the minute, the hour and the day.
+// buckets returns c's buckets of requests in the minute, the hour and the
+// day.
 func (c *Client) buckets() [3]*Buckets {
 	return [3]*Buckets{&c.Minute, &c.Hour, &c.Day}
 }
 
-// window is a length of time over which requests are counted, and the
-// most requests a client may make in it.
-type window struct {
-	name   string
-	length time.Duration
-	limit  int64
+// byteBuckets returns c's buckets of bytes in the minute, the hour and the
+// day.
+func (c *Client) byteBuckets() [3]*Buckets {
+	return [3]*Buckets{&c.MinuteBytes, &c.HourBytes, &c.DayBytes}
 }
 
-// add counts a request at now in a window of length, and returns the
-// client's requests in the window that ends at now: those in the bucket
-// under way, and those in the bucket before it weighted by how much of
-// that bucket the window still covers.
+// window is a length of time over which requests and bytes are counted,
+// and the most requests and the most bytes a client may have in it.
+type window struct {
+	name      string
+	length    time.Duration
+	limit     int64
+	byteLimit int64
+}
+
+// percentOf returns the percentage percent of limit, rounded down. It is
+// written as limit's hundreds times percent, plus the rest's share, since
+// limit*percent can overflow for a byte limit.
+func percentOf(limit, percent int64) int64 {
+	const hundred = 100
+
+	return limit/hundred*percent + limit%hundred*percent/hundred
+}
+
+// Add counts n requests, or n bytes, at now in a window of length, and
+// returns the count in the window that ends at now: what is in the bucket
+// under way, and what is in the bucket before it weighted by how much of
+// that bucket the window still covers. With n zero it counts nothing, and
+// returns the count. The anomaly counters count in Buckets too.
 //
 // Concurrent requests can be counted out of order, so now can be a moment
 // before the bucket under way began; such a request is counted in that
 // bucket. A request dated more than a second before it means the clock
 // was set back, and the buckets start afresh: otherwise the bucket before
 // would keep its full weight until the clock caught up.
-func (b *Buckets) add(now time.Time, length time.Duration) float64 {
+func (b *Buckets) Add(now time.Time, length time.Duration, n int64) float64 {
 	if now.Before(b.Start.Add(-time.Second)) {
 		*b = Buckets{}
 	}
@@ -393,7 +503,7 @@ func (b *Buckets) add(now time.Time, length time.Duration) float64 {
 		b.Current = 0
 	}
 
-	b.Current++
+	b.Current += n
 
 	elapsed := max(now.Sub(b.Start), 0)
 	covered := 1 - float64(elapsed)/float64(length)
@@ -401,6 +511,14 @@ func (b *Buckets) add(now time.Time, length time.Duration) float64 {
 	return float64(b.Previous)*covered + float64(b.Current)
 }
 
+// Passed reports whether the window of length that ends at now covers
+// neither of b's buckets: it begins after the bucket under way has ended.
+// What they hold then counts no more, and a state file read at now drops
+// it.
+func (b *Buckets) Passed(now time.Time, length time.Duration) bool {
+	return !now.Add(-length).Before(b.Start.Add(length))
+}
+
 // add counts a response with status in its class. A status of 0, for
 // nothing sent, is not a response.
 func (r *Responses) add(status int) {

internal/ratelimit/ratelimit_test.go

@@ -1,6 +1,7 @@
 package ratelimit_test
 
 import (
+	"math"
 	"net/netip"
 	"testing"
 	"time"
@@ -11,6 +12,10 @@ import (
 // limit is the limit the tests set.
 const limit = 3
 
+// whole is the percentage of each limit a client gets when nothing lowers
+// its limits.
+const whole = 100
+
 // The windows, as Count names them.
 const (
 	minute = "minute"
@@ -62,22 +67,180 @@ func TestHitGivesTheLimitAndTheRequestsCounted(t *testing.T) {
 	start := midnight()
 
 	for range limit {
-		_, _, over := limiter.Count(client, start)
+		_, _, over := limiter.Count(client, start, whole)
 		if over {
 			t.Fatal("a request within the limit is over it")
 		}
 	}
 
 	// Over both limits; the minute's is named, with the four requests.
-	_, hit, over := limiter.Count(client, start)
+	_, hit, over := limiter.Count(client, start, whole)
 
-	want := ratelimit.Hit{Window: minute, Limit: limit, Requests: limit + 1}
+	want := ratelimit.Hit{
+		Kind: ratelimit.KindRequests, Window: minute, Limit: limit, Count: limit + 1,
+	}
 	if !over || hit != want {
 		t.Errorf("request over the limit gives %+v and %t, want %+v and true",
 			hit, over, want)
 	}
 }
 
+func TestClientGetsItsPercentageOfEachLimitRoundedDown(t *testing.T) {
+	t.Parallel()
+
+	limiter := ratelimit.New(ratelimit.Limits{PerMinute: 5, BytesPerDay: math.MaxInt64})
+	client := netip.MustParsePrefix("203.0.113.9/32")
+	start := midnight()
+
+	// Half of 5 requests is 2.5, rounded down to 2: the third is over.
+	for range 2 {
+		_, _, over := limiter.Count(client, start, 50)
+		if over {
+			t.Fatal("a request within half the limit is over it")
+		}
+	}
+
+	_, hit, over := limiter.Count(client, start, 50)
+
+	want := ratelimit.Hit{Kind: ratelimit.KindRequests, Window: minute, Limit: 2, Count: 3}
+	if !over || hit != want {
+		t.Errorf("the third request gives %+v and %t, want %+v and true", hit, over, want)
+	}
+
+	// Half of the largest byte limit is still far above a TiB: working it
+	// out does not overflow.
+	_, hit, over = limiter.CountBytes(client, start, 1<<40, 50)
+	if over {
+		t.Errorf("a TiB is over half the largest byte limit: %+v", hit)
+	}
+}
+
+func TestZeroPercentIsAZeroAllowanceAndALimitOffStaysOff(t *testing.T) {
+	t.Parallel()
+
+	// Only the hour has limits: the minute's and the day's are off.
+	limiter := ratelimit.New(ratelimit.Limits{PerHour: limit, BytesPerHour: 1000})
+	client := netip.MustParsePrefix("203.0.113.9/32")
+	start := midnight()
+
+	// At 0 percent, the first request and the first byte are over the
+	// hour's limits, which are 0; the minute's, which are off, stay off.
+	_, hit, _ := limiter.Count(client, start, 0)
+
+	want := ratelimit.Hit{Kind: ratelimit.KindRequests, Window: hour, Limit: 0, Count: 1}
+	if hit != want {
+		t.Errorf("the first request gives %+v, want %+v", hit, want)
+	}
+
+	_, hit, _ = limiter.CountBytes(client, start, 1, 0)
+
+	want = ratelimit.Hit{Kind: ratelimit.KindBytes, Window: hour, Limit: 0, Count: 1}
+	if hit != want {
+		t.Errorf("the first byte gives %+v, want %+v", hit, want)
+	}
+}
+
+func TestEachByteLimitIsBrokenByTheBytesCounted(t *testing.T) {
+	t.Parallel()
+
+	const byteLimit = 1000
+
+	for _, tc := range []struct {
+		window string
+		limits ratelimit.Limits
+	}{
+		{minute, ratelimit.Limits{BytesPerMinute: byteLimit}},
+		{hour, ratelimit.Limits{BytesPerHour: byteLimit}},
+		{"day", ratelimit.Limits{BytesPerDay: byteLimit}},
+	} {
+		t.Run(tc.window, func(t *testing.T) {
+			t.Parallel()
+
+			limiter := ratelimit.New(tc.limits)
+			client := netip.MustParsePrefix("203.0.113.9/32")
+
+			// 600 bytes are within the limit, 600 more over it.
+			_, _, over := limiter.CountBytes(client, midnight(), 600, whole)
+			if over {
+				t.Fatal("600 bytes are over the limit of 1000")
+			}
+
+			_, hit, over := limiter.CountBytes(client, midnight(), 600, whole)
+
+			want := ratelimit.Hit{
+				Kind: ratelimit.KindBytes, Window: tc.window, Limit: byteLimit, Count: 1200,
+			}
+			if !over || hit != want {
+				t.Errorf("1200 bytes give %+v and %t, want %+v and true", hit, over, want)
+			}
+		})
+	}
+}
+
+func TestALimitIsBrokenOnlyByWhatIsAddedToIt(t *testing.T) {
+	t.Parallel()
+
+	limiter := ratelimit.New(ratelimit.Limits{PerMinute: 2, BytesPerMinute: 1000})
+	client := netip.MustParsePrefix("203.0.113.9/32")
+	other := netip.MustParsePrefix("203.0.113.10/32")
+	start := midnight()
+
+	// The third request breaks the rate limit. The bytes of a request
+	// counted after it, within the byte limit, do not break it again.
+	for range 2 {
+		wantCount(t, limiter, client, start, "")
+	}
+
+	wantCount(t, limiter, client, start, minute)
+	wantBytesCount(t, limiter, client, start, 500, "")
+	wantBytesCount(t, limiter, client, start, 600, ratelimit.KindBytes)
+
+	// Bytes over the byte limit do not have the next request break it, nor
+	// the rate limit, which that request is within.
+	wantBytesCount(t, limiter, other, start, 1200, ratelimit.KindBytes)
+	wantCount(t, limiter, other, start, "")
+}
+
+func TestCountGivesTheBytesInEachWindow(t *testing.T) {
+	t.Parallel()
+
+	limiter := ratelimit.New(ratelimit.Limits{})
+	client := netip.MustParsePrefix("203.0.113.9/32")
+	start := midnight()
+
+	limiter.CountBytes(client, start, 300, whole)
+
+	// A quarter into the next hour, the minute has only these 100 bytes.
+	// The hour still covers three quarters of the bucket before, whose 300
+	// bytes count 225, and these: 325. The day covers all 400.
+	later := start.Add(time.Hour + time.Hour/4)
+	limiter.CountBytes(client, later, 100, whole)
+
+	// A request's counts give the bytes counted so far too.
+	counts, _, _ := limiter.Count(client, later, whole)
+
+	want := ratelimit.Counts{
+		Minute: 1, Hour: 1, Day: 1, MinuteBytes: 100, HourBytes: 325, DayBytes: 400,
+	}
+	if counts != want {
+		t.Errorf("counts %+v, want %+v", counts, want)
+	}
+}
+
+func TestResetSetsTheBytesBackToZero(t *testing.T) {
+	t.Parallel()
+
+	limiter := ratelimit.New(ratelimit.Limits{BytesPerDay: 1000})
+	client := netip.MustParsePrefix("203.0.113.9/32")
+	start := midnight()
+
+	wantBytesCount(t, limiter, client, start, 1200, ratelimit.KindBytes)
+	limiter.Reset(client)
+
+	// The client has its whole allowance of bytes again.
+	wantBytesCount(t, limiter, client, start, 1000, "")
+}
+
 func TestCountGivesTheRequestsInEachWindow(t *testing.T) {
 	t.Parallel()
 
@@ -86,14 +249,14 @@ func TestCountGivesTheRequestsInEachWindow(t *testing.T) {
 	start := midnight()
 
 	for range 3 {
-		limiter.Count(client, start)
+		limiter.Count(client, start, whole)
 	}
 
 	// A quarter into the next hour, the minute has only this request. The
 	// hour still covers three quarters of the bucket before, with its three
 	// requests, which count 2.25, and this one: 3.25. The day covers all
 	// four.
-	counts, _, _ := limiter.Count(client, start.Add(time.Hour+time.Hour/4))
+	counts, _, _ := limiter.Count(client, start.Add(time.Hour+time.Hour/4), whole)
 
 	want := ratelimit.Counts{Minute: 1, Hour: 3.25, Day: 4}
 	if counts != want {
@@ -261,9 +424,24 @@ func wantCount(
 ) {
 	t.Helper()
 
-	_, hit, _ := limiter.Count(client, now)
+	_, hit, _ := limiter.Count(client, now, whole)
 	if hit.Window != want {
 		t.Errorf("request from %s at %s is over %q, want %q",
 			client, now.Format(time.RFC3339), hit.Window, want)
 	}
 }
+
+// wantBytesCount counts bytes from client at now, and checks the kind of
+// the limit they break, "" for none.
+func wantBytesCount(
+	t *testing.T, limiter *ratelimit.Limiter, client netip.Prefix, now time.Time,
+	bytes int64, want string,
+) {
+	t.Helper()
+
+	_, hit, _ := limiter.CountBytes(client, now, bytes, whole)
+	if hit.Kind != want {
+		t.Errorf("%d bytes from %s at %s break a limit on %q, want %q",
+			bytes, client, now.Format(time.RFC3339), hit.Kind, want)
+	}
+}

internal/ratelimit/snapshot_test.go

@@ -16,7 +16,7 @@ func TestSnapshotListsTheClientsByAddress(t *testing.T) {
 
 	limiter := ratelimit.New(ratelimit.Limits{})
 	for _, i := range []int{2, 3, 0, 1} {
-		limiter.Count(netip.MustParsePrefix(want[i]), midnight())
+		limiter.Count(netip.MustParsePrefix(want[i]), midnight(), whole)
 	}
 
 	snapshot := limiter.Snapshot()
@@ -63,7 +63,8 @@ func TestLoadEmptiesBucketsWhoseTimeHasPassed(t *testing.T) {
 	start := midnight()
 
 	limiter := ratelimit.New(ratelimit.Limits{})
-	limiter.Count(client, start)
+	limiter.Count(client, start, whole)
+	limiter.CountBytes(client, start, 5, whole)
 	limiter.AddToHistory(client, start, ratelimit.Request{Forwarded: true})
 
 	loaded := func(now time.Time) ratelimit.Client {
@@ -76,19 +77,25 @@ func TestLoadEmptiesBucketsWhoseTimeHasPassed(t *testing.T) {
 	}
 
 	// Two minutes on, the window that ends then covers neither of the
-	// minute's buckets, which are emptied; the hour's and the day's stay,
-	// and so does the history.
+	// minute's buckets, of requests and of bytes, which are emptied; the
+	// hour's and the day's stay, and so does the history.
 	got := loaded(start.Add(2 * time.Minute))
 	if got.Minute != (ratelimit.Buckets{}) || got.Hour.Current != 1 ||
 		got.Day.Current != 1 || got.History.Requests != 1 {
 		t.Errorf("loaded two minutes on as %+v", got)
 	}
 
+	if got.MinuteBytes != (ratelimit.Buckets{}) || got.HourBytes.Current != 5 ||
+		got.DayBytes.Current != 5 {
+		t.Errorf("loaded two minutes on with buckets of bytes %+v, %+v and %+v",
+			got.MinuteBytes, got.HourBytes, got.DayBytes)
+	}
+
 	// A moment before, the window still covers some of the earlier one.
 	got = loaded(start.Add(2*time.Minute - time.Nanosecond))
-	if got.Minute.Current != 1 {
-		t.Errorf("loaded just under two minutes on with minute buckets %+v",
-			got.Minute)
+	if got.Minute.Current != 1 || got.MinuteBytes.Current != 5 {
+		t.Errorf("loaded just under two minutes on with minute buckets %+v and %+v",
+			got.Minute, got.MinuteBytes)
 	}
 }
 

internal/reputation/abuseipdb.go

@@ -0,0 +1,328 @@
+package reputation
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/netip"
+	"net/url"
+	"slices"
+	"sync"
+	"time"
+
+	"github.com/hashicorp/golang-lru/v2/simplelru"
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+)
+
+const (
+	// AbuseIPDBURL is where clients are checked: the check endpoint of
+	// AbuseIPDB's API.
+	AbuseIPDBURL = "https://api.abuseipdb.com/api/v2/check"
+	// AbuseIPDBSource is how the request log, the alerts and the metrics
+	// name AbuseIPDB.
+	AbuseIPDBSource = "abuseipdb"
+	// maxAnswerBytes is the most of an answer of AbuseIPDB that is read.
+	maxAnswerBytes = 64 << 10
+	// day is the length of the day the checks are counted in, in UTC.
+	day = 24 * time.Hour
+)
+
+var (
+	errNoScore      = errors.New("the answer gives no abuseConfidenceScore")
+	errBudgetUsedUp = errors.New(
+		"checks spent; none is made until the day ends at 00:00 UTC")
+)
+
+// Score is what AbuseIPDB said about a client, as reputation.json holds
+// it: the client, an IPv4 address or an IPv6 group, its abuse confidence
+// score, from 0 to 100, and when AbuseIPDB answered.
+type Score struct {
+	Client  netip.Prefix `json:"client"`
+	Score   int64        `json:"score"`
+	Fetched time.Time    `json:"fetched"`
+}
+
+// Checks are what reputation.json keeps of the checks of clients with
+// AbuseIPDB: the day, in UTC, of the checks Spent counts, zero before the
+// first, and the scores still in use.
+type Checks struct {
+	Day    time.Time `json:"day,omitzero"`
+	Spent  int       `json:"spent"`
+	Scores []Score   `json:"scores"`
+}
+
+// AbuseIPDBParams are what NewAbuseIPDB needs.
+type AbuseIPDBParams struct {
+	// URL is where clients are checked, normally AbuseIPDBURL, with Key,
+	// the account's key (SWWAF_ABUSEIPDB_KEY).
+	URL string
+	Key string
+	// MinScore is the least score that is a hit (SWWAF_ABUSEIPDB_MIN_SCORE),
+	// and DailyBudget the most checks made in a day, in UTC
+	// (SWWAF_ABUSEIPDB_DAILY_BUDGET).
+	MinScore    int64
+	DailyBudget int
+	// CacheTTL is how long a score is used after it was fetched
+	// (SWWAF_REPUTATION_CACHE_TTL), and Timeout how long a check may take
+	// (SWWAF_REPUTATION_TIMEOUT).
+	CacheTTL time.Duration
+	Timeout  time.Duration
+	// Now tells the time, normally time.Now in UTC.
+	Now func() time.Time
+	// ProcessLog receives each check that fails, and why, and the day's
+	// budget used up.
+	ProcessLog *slog.Logger
+	// Alerts receive a source_failure alert for each.
+	Alerts *alerts.Queue
+}
+
+// AbuseIPDB checks clients with AbuseIPDB, in the background, and keeps
+// their scores. It is safe for concurrent use.
+type AbuseIPDB struct {
+	params     AbuseIPDBParams
+	httpClient *http.Client
+
+	mu sync.Mutex
+	// scores are by client. Each is added as it is fetched and never moved
+	// up, so that the one fetched longest ago is the first dropped.
+	scores *simplelru.LRU[netip.Prefix, Score]
+	// checking are the clients whose check is under way.
+	checking map[netip.Prefix]bool
+	// day is the day, in UTC, of the checks spent counts.
+	day   time.Time
+	spent int
+	// checks and failures count the checks made and those that failed,
+	// and retryAt is when a client may be checked again after the last
+	// check failed.
+	checks   int
+	failures int
+	retryAt  time.Time
+}
+
+// NewAbuseIPDB returns an AbuseIPDB with no score yet, and no check spent.
+func NewAbuseIPDB(params AbuseIPDBParams) *AbuseIPDB {
+	scores, err := simplelru.NewLRU[netip.Prefix, Score](maxVerdicts, nil)
+	if err != nil {
+		panic(err) // NewLRU fails only for a size below one
+	}
+
+	return &AbuseIPDB{
+		params:     params,
+		httpClient: &http.Client{},
+		scores:     scores,
+		checking:   map[netip.Prefix]bool{},
+	}
+}
+
+// Hit returns AbuseIPDB's score of client, an IPv4 address or an IPv6
+// group, and whether it is a hit: MinScore or more. A score is used until
+// CacheTTL has passed since it was fetched, whichever of the client's
+// addresses its request comes from. A client without one is checked in
+// the background, by addr, the address its request came from, if
+// offender, if it has committed an offence, unless its check is under
+// way, a check failed less than failureDelay ago, or the day's checks
+// have used up DailyBudget; Hit never waits for a check. The check that
+// uses the budget up is logged and raised as a source_failure alert. ctx
+// is the context of the client's request, and a check goes on after the
+// request ends.
+func (a *AbuseIPDB) Hit(
+	ctx context.Context, client netip.Prefix, addr netip.Addr, offender bool,
+) (int64, bool) {
+	a.mu.Lock()
+
+	now := a.params.Now()
+
+	kept, found := a.scores.Peek(client)
+	if found && now.Sub(kept.Fetched) < a.params.CacheTTL {
+		a.mu.Unlock()
+
+		return kept.Score, kept.Score >= a.params.MinScore
+	}
+
+	if today := now.Truncate(day); !a.day.Equal(today) {
+		a.day, a.spent = today, 0
+	}
+
+	check := offender && !a.checking[client] && !now.Before(a.retryAt) &&
+		a.spent < a.params.DailyBudget
+	if check {
+		a.checking[client] = true
+		a.checks++
+		a.spent++
+
+		go a.check(context.WithoutCancel(ctx), client, addr)
+	}
+
+	usedUp := check && a.spent == a.params.DailyBudget
+
+	a.mu.Unlock()
+
+	if usedUp {
+		a.alert("the daily budget of AbuseIPDB checks is used up",
+			fmt.Errorf("%d %w", a.params.DailyBudget, errBudgetUsedUp))
+	}
+
+	return 0, false
+}
+
+// Checked returns how many checks were made.
+func (a *AbuseIPDB) Checked() int {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+
+	return a.checks
+}
+
+// Failures returns how many checks failed.
+func (a *AbuseIPDB) Failures() int {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+
+	return a.failures
+}
+
+// BudgetLeft returns how many checks the day's budget has left.
+func (a *AbuseIPDB) BudgetLeft() int {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+
+	if !a.day.Equal(a.params.Now().Truncate(day)) {
+		return a.params.DailyBudget
+	}
+
+	return max(a.params.DailyBudget-a.spent, 0)
+}
+
+// Snapshot returns the checks spent and every score still in use, sorted
+// by client, as reputation.json keeps them.
+func (a *AbuseIPDB) Snapshot() Checks {
+	a.mu.Lock()
+
+	now := a.params.Now()
+	checks := Checks{Day: a.day, Spent: a.spent, Scores: make([]Score, 0, a.scores.Len())}
+
+	for _, kept := range a.scores.Values() {
+		if now.Sub(kept.Fetched) < a.params.CacheTTL {
+			checks.Scores = append(checks.Scores, kept)
+		}
+	}
+
+	a.mu.Unlock()
+
+	slices.SortFunc(checks.Scores, func(x, y Score) int {
+		return x.Client.Compare(y.Client)
+	})
+
+	return checks
+}
+
+// Load keeps checks, read from reputation.json, in place of those it
+// keeps, but for the scores past maxVerdicts, those fetched longest ago.
+// One fetched CacheTTL ago or more is neither used nor written, as for any
+// score.
+func (a *AbuseIPDB) Load(checks Checks) {
+	scores := slices.Clone(checks.Scores)
+	slices.SortStableFunc(scores, func(x, y Score) int {
+		return x.Fetched.Compare(y.Fetched)
+	})
+
+	a.mu.Lock()
+	defer a.mu.Unlock()
+
+	a.day, a.spent = checks.Day, checks.Spent
+	a.scores.Purge()
+
+	for _, kept := range scores {
+		a.scores.Add(kept.Client, kept)
+	}
+}
+
+// check checks client with AbuseIPDB by addr, one of its addresses, keeps
+// the score as client's, and notes the check as no longer under way. A
+// check that fails gives no score: it is counted, logged and raised as a
+// source_failure alert, and no client is checked for failureDelay.
+func (a *AbuseIPDB) check(ctx context.Context, client netip.Prefix, addr netip.Addr) {
+	score, err := a.ask(ctx, addr)
+	now := a.params.Now()
+
+	a.mu.Lock()
+
+	delete(a.checking, client)
+
+	if err == nil {
+		a.scores.Add(client, Score{Client: client, Score: score, Fetched: now})
+	} else {
+		a.failures++
+		a.retryAt = now.Add(failureDelay)
+	}
+
+	a.mu.Unlock()
+
+	if err != nil {
+		a.alert("checking a client with AbuseIPDB failed", err)
+	}
+}
+
+// ask asks AbuseIPDB for addr's abuse confidence score, sending the key
+// in the header Key. An answer other than 200, one that gives no score,
+// and none within Timeout, fail.
+func (a *AbuseIPDB) ask(ctx context.Context, addr netip.Addr) (int64, error) {
+	ctx, cancel := context.WithTimeout(ctx, a.params.Timeout)
+	defer cancel()
+
+	query := url.Values{"ipAddress": {addr.String()}}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet,
+		a.params.URL+"?"+query.Encode(), http.NoBody)
+	if err != nil {
+		return 0, fmt.Errorf("make the request: %w", err)
+	}
+
+	req.Header.Set("Key", a.params.Key)
+	req.Header.Set("Accept", "application/json")
+
+	res, err := a.httpClient.Do(req)
+	if err != nil {
+		// Do's error names the URL, which holds the client's address, which
+		// is not to be logged: only what went wrong is kept.
+		return 0, fmt.Errorf("check the client: %w", errors.Unwrap(err))
+	}
+
+	defer func() {
+		_ = res.Body.Close()
+	}()
+
+	if res.StatusCode != http.StatusOK {
+		return 0, fmt.Errorf("%w %s", errStatus, res.Status)
+	}
+
+	var answer struct {
+		Data struct {
+			AbuseConfidenceScore *int64 `json:"abuseConfidenceScore"`
+		} `json:"data"`
+	}
+
+	err = json.NewDecoder(io.LimitReader(res.Body, maxAnswerBytes)).Decode(&answer)
+	if err != nil {
+		return 0, fmt.Errorf("read the answer: %w", err)
+	}
+
+	if answer.Data.AbuseConfidenceScore == nil {
+		return 0, errNoScore
+	}
+
+	return *answer.Data.AbuseConfidenceScore, nil
+}
+
+// alert raises a source_failure alert from AbuseIPDB with reason and err,
+// and logs them.
+func (a *AbuseIPDB) alert(reason string, err error) {
+	// Raised before it is logged, so that the alert is there once the log
+	// line is.
+	raiseFailure(a.params.Alerts, reason, AbuseIPDBSource, err)
+	a.params.ProcessLog.Warn(reason, "source", AbuseIPDBSource, "error", err.Error())
+}

internal/reputation/abuseipdb_test.go

@@ -0,0 +1,663 @@
+package reputation_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"net/netip"
+	"reflect"
+	"slices"
+	"strings"
+	"sync"
+	"testing"
+	"testing/synctest"
+	"time"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/metrics"
+	"sneak.berlin/go/smallwebwaf/internal/reputation"
+)
+
+// The tests of AbuseIPDB run in synctest bubbles, as those of the lists
+// do, and AbuseIPDB is a stand-in reached without the network, for the
+// same reason. A bubble's clock starts at midnight UTC, as a day the
+// checks are counted in starts.
+
+const (
+	// key is the account's key the tests give, the only one the stand-in
+	// takes.
+	key = "abuseipdb-key-0123456789abcdef"
+	// suspect and other are clients that have committed an offence.
+	suspect = "203.0.113.9"
+	other   = "2001:db8::9"
+)
+
+func TestOnlyAnOffenderWithoutAScoreIsChecked(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		abuseIPDB := &abuseIPDBStandIn{scores: map[string]int64{suspect: 100}}
+		checker := newAbuseIPDB(abuseIPDB, abuseIPDBParams())
+
+		// A client that has committed no offence is not checked.
+		wantScore(t, checker, suspect, false, 0, false)
+		synctest.Wait()
+		wantChecked(t, abuseIPDB)
+
+		// An offender is, and from then on its score is used, whether or not
+		// it is an offender.
+		wantScore(t, checker, suspect, true, 0, false)
+		synctest.Wait()
+		wantScore(t, checker, suspect, true, 100, true)
+		wantScore(t, checker, suspect, false, 100, true)
+		synctest.Wait()
+		wantChecked(t, abuseIPDB, suspect)
+	})
+}
+
+func TestIPv6ClientIsCheckedOnceAndItsScoreUsedForEachOfItsAddresses(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		// 15 addresses of 2001:db8:1:2::/64, one client, each in a part of
+		// it of its own.
+		var addresses []string
+		for i := 1; i < 16; i++ {
+			addresses = append(addresses, fmt.Sprintf("2001:db8:1:2:%x::9", i<<12))
+		}
+
+		abuseIPDB := &abuseIPDBStandIn{scores: map[string]int64{addresses[0]: 100}}
+		checker := newAbuseIPDB(abuseIPDB, abuseIPDBParams())
+
+		// A request from each has the client checked once, by the first.
+		for _, address := range addresses {
+			hitFrom(t, checker, address, true)
+		}
+
+		synctest.Wait()
+		wantChecked(t, abuseIPDB, addresses[0])
+
+		// Its score is the whole client's.
+		for _, address := range addresses {
+			wantScore(t, checker, address, true, 100, true)
+		}
+
+		synctest.Wait()
+		wantChecked(t, abuseIPDB, addresses[0])
+	})
+}
+
+func TestScoreAtOrOverTheMinimumIsAHit(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		scores := map[string]int64{"192.0.2.74": 74, "192.0.2.75": 75, "192.0.2.100": 100}
+		p := abuseIPDBParams()
+		p.MinScore = 75
+		checker := newAbuseIPDB(&abuseIPDBStandIn{scores: scores}, p)
+
+		for client := range scores {
+			hitFrom(t, checker, client, true)
+		}
+
+		synctest.Wait()
+
+		for client, score := range scores {
+			wantScore(t, checker, client, true, score, score >= 75)
+		}
+	})
+}
+
+func TestScoreUsedUntilTheCacheTTLHasPassedSinceItWasFetched(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		abuseIPDB := &abuseIPDBStandIn{scores: map[string]int64{suspect: 100}}
+		checker := newAbuseIPDB(abuseIPDB, abuseIPDBParams())
+
+		hitFrom(t, checker, suspect, true)
+		synctest.Wait()
+
+		// AbuseIPDB gives another score from now on, but the one kept is
+		// used, and the client is not checked again, until the TTL has
+		// passed.
+		abuseIPDB.setScore(suspect, 80)
+		time.Sleep(cacheTTL - time.Nanosecond)
+		wantScore(t, checker, suspect, true, 100, true)
+		synctest.Wait()
+		wantChecked(t, abuseIPDB, suspect)
+
+		// Then it is not used, and the client is checked again.
+		time.Sleep(time.Nanosecond)
+		wantScore(t, checker, suspect, true, 0, false)
+		synctest.Wait()
+		wantScore(t, checker, suspect, true, 80, true)
+		wantChecked(t, abuseIPDB, suspect, suspect)
+	})
+}
+
+func TestDailyBudgetKeptAcrossARestartAndWholeAgainAsTheDayEnds(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		var log bytes.Buffer
+
+		queue := newQueue()
+		p := abuseIPDBParams()
+		p.DailyBudget = 3
+		p.Alerts = queue
+		p.ProcessLog = slog.New(slog.NewJSONHandler(&log, nil))
+		abuseIPDB := &abuseIPDBStandIn{scores: map[string]int64{suspect: 100}}
+		checker := newAbuseIPDB(abuseIPDB, p)
+
+		// At noon, the first three offenders spend the budget, and the
+		// fourth, unchecked, is not.
+		time.Sleep(12 * time.Hour)
+
+		const unchecked = "192.0.2.4"
+
+		clients := []string{suspect, "192.0.2.2", "192.0.2.3", unchecked}
+		for _, client := range clients {
+			hitFrom(t, checker, client, true)
+		}
+
+		synctest.Wait()
+		wantChecked(t, abuseIPDB, clients[:3]...)
+		wantBudgetLeft(t, checker, 0)
+
+		// The check that used the budget up raised the alert, and logged it.
+		const usedUp = "the daily budget of AbuseIPDB checks is used up"
+
+		wantFailureAlert(t, queue, time.Now(), usedUp,
+			"3 checks spent; none is made until the day ends at 00:00 UTC", 0)
+
+		if !strings.Contains(log.String(), `"msg":"`+usedUp+`"`) {
+			t.Errorf("logged\n%s\nwant the budget used up", log.String())
+		}
+
+		// Restarted with what reputation.json keeps, it uses the scores, and
+		// checks no client until the day ends.
+		restarted := &abuseIPDBStandIn{}
+		again := newAbuseIPDB(restarted, p)
+		again.Load(checker.Snapshot())
+
+		wantScore(t, again, suspect, true, 100, true)
+		wantBudgetLeft(t, again, 0)
+		time.Sleep(12*time.Hour - time.Nanosecond)
+		wantScore(t, again, unchecked, true, 0, false)
+		synctest.Wait()
+		wantChecked(t, restarted)
+
+		// At midnight the budget is whole again.
+		time.Sleep(time.Nanosecond)
+		wantBudgetLeft(t, again, 3)
+		wantScore(t, again, unchecked, true, 0, false)
+		synctest.Wait()
+		wantChecked(t, restarted, unchecked)
+		wantBudgetLeft(t, again, 2)
+	})
+}
+
+func TestFailedCheckGivesNoScoreAndNoClientIsCheckedForAMinute(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name string
+		// key is the key sent, status and body what AbuseIPDB answers with,
+		// and error the failure.
+		key, body string
+		status    int
+		error     string
+	}{
+		{
+			"a refusal, past AbuseIPDB's own limit", key,
+			`{"errors":[{"detail":"Daily rate limit of 1000 requests exceeded"}]}`,
+			http.StatusTooManyRequests, "the server answered 429 Too Many Requests",
+		},
+		{
+			"a refusal of a wrong key", "wrong-key-0123456789abcdef", "", 0,
+			"the server answered 401 Unauthorized",
+		},
+		{
+			"a server failure", key, "", http.StatusInternalServerError,
+			"the server answered 500 Internal Server Error",
+		},
+		{
+			"an answer without a score", key, `{"data":{"ipAddress":"` + suspect + `"}}`,
+			http.StatusOK, "the answer gives no abuseConfidenceScore",
+		},
+		{
+			"an answer that is not JSON", key, "<html>", http.StatusOK,
+			"read the answer: invalid character '<' looking for beginning of value",
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			synctest.Test(t, func(t *testing.T) {
+				var log bytes.Buffer
+
+				queue := newQueue()
+				p := abuseIPDBParams()
+				p.Key = tc.key
+				p.Alerts = queue
+				p.ProcessLog = slog.New(slog.NewJSONHandler(&log, nil))
+				abuseIPDB := &abuseIPDBStandIn{status: tc.status, body: tc.body}
+				checker := newAbuseIPDB(abuseIPDB, p)
+
+				// The failure gives no score, and no client is checked within a
+				// minute of it.
+				wantScore(t, checker, suspect, true, 0, false)
+				synctest.Wait()
+				time.Sleep(time.Minute - time.Nanosecond)
+				wantScore(t, checker, other, true, 0, false)
+				synctest.Wait()
+				wantChecked(t, abuseIPDB, suspect)
+				wantFailures(t, checker, 1)
+
+				time.Sleep(time.Nanosecond)
+				wantScore(t, checker, other, true, 0, false)
+				synctest.Wait()
+				wantChecked(t, abuseIPDB, suspect, other)
+				wantFailures(t, checker, 2)
+
+				if scores := checker.Snapshot().Scores; len(scores) != 0 {
+					t.Errorf("scores %+v, want none", scores)
+				}
+
+				// One alert for the first failure; the cooldown holds back the
+				// second.
+				wantFailureAlert(t, queue, time.Now().Add(-time.Minute),
+					"checking a client with AbuseIPDB failed", tc.error, 1)
+
+				if !strings.Contains(log.String(), `"msg":"checking a client with `+
+					`AbuseIPDB failed","source":"abuseipdb","error":"`+tc.error) {
+					t.Errorf("logged\n%s\nwant the failures", log.String())
+				}
+			})
+		})
+	}
+}
+
+func TestCheckNotAnsweredWithinTheTimeoutFailsAndHitNeverWaits(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		queue := newQueue()
+		p := abuseIPDBParams()
+		p.Alerts = queue
+		abuseIPDB := &abuseIPDBStandIn{hanging: true}
+		checker := newAbuseIPDB(abuseIPDB, p)
+		began := time.Now()
+
+		// The second, while the first's check is under way, starts none.
+		wantScore(t, checker, suspect, true, 0, false)
+		wantScore(t, checker, suspect, true, 0, false)
+
+		if waited := time.Since(began); waited != 0 {
+			t.Errorf("waited %s for the check, want no wait", waited)
+		}
+
+		time.Sleep(timeout - time.Nanosecond)
+		synctest.Wait()
+		wantChecked(t, abuseIPDB, suspect)
+		wantFailures(t, checker, 0)
+
+		time.Sleep(time.Nanosecond)
+		synctest.Wait()
+		wantFailures(t, checker, 1)
+		wantFailureAlert(t, queue, time.Now(), "checking a client with AbuseIPDB failed",
+			"check the client: context deadline exceeded", 0)
+	})
+}
+
+func TestKeyIsSentInTheKeyHeaderAndNeverShown(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		var log bytes.Buffer
+
+		queue := newQueue()
+		p := abuseIPDBParams()
+		p.Alerts = queue
+		p.ProcessLog = slog.New(slog.NewJSONHandler(&log, nil))
+		abuseIPDB := &abuseIPDBStandIn{scores: map[string]int64{suspect: 100}}
+		checker := newAbuseIPDB(abuseIPDB, p)
+		m := metrics.New(1, "app")
+		m.AddReputation(reputation.New(params()), reputation.NewDNSBL(dnsblParams()))
+		m.AddAbuseIPDB(checker)
+
+		// One check that AbuseIPDB answers, and one it refuses with an answer
+		// that names the key.
+		wantScore(t, checker, suspect, true, 0, false)
+		synctest.Wait()
+		wantScore(t, checker, suspect, true, 100, true)
+
+		abuseIPDB.answerWith(http.StatusUnauthorized, `{"errors":[{"detail":"`+key+`"}]}`)
+		wantScore(t, checker, other, true, 0, false)
+		synctest.Wait()
+		wantFailures(t, checker, 1)
+
+		abuseIPDB.mu.Lock()
+		sent := slices.Clone(abuseIPDB.keys)
+		abuseIPDB.mu.Unlock()
+
+		if !slices.Equal(sent, []string{key, key}) {
+			t.Errorf("checks sent the keys %v, want %s twice", sent, key)
+		}
+
+		alerted, err := json.Marshal(waiting(queue))
+		if err != nil {
+			t.Fatalf("encode the alerts: %v", err)
+		}
+
+		kept, err := json.Marshal(checker.Snapshot())
+		if err != nil {
+			t.Fatalf("encode the checks: %v", err)
+		}
+
+		for name, shown := range map[string]string{
+			"the log": log.String(), "the alerts": string(alerted),
+			"the metrics": scrapeMetrics(t, m), "reputation.json": string(kept),
+		} {
+			if strings.Contains(shown, key) {
+				t.Errorf("%s shows the key:\n%s", name, shown)
+			}
+		}
+	})
+}
+
+func TestMetricsCountTheChecksTheFailuresAndTheBudgetLeft(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		abuseIPDB := &abuseIPDBStandIn{}
+		p := abuseIPDBParams()
+		p.DailyBudget = 5
+		checker := newAbuseIPDB(abuseIPDB, p)
+		m := metrics.New(1, "app")
+		m.AddReputation(reputation.New(params()), reputation.NewDNSBL(dnsblParams()))
+		m.AddAbuseIPDB(checker)
+
+		// One check that AbuseIPDB answers, and one that fails.
+		hitFrom(t, checker, suspect, true)
+		synctest.Wait()
+		abuseIPDB.answerWith(http.StatusInternalServerError, "")
+		hitFrom(t, checker, other, true)
+		synctest.Wait()
+
+		scraped := scrapeMetrics(t, m)
+
+		for series, want := range map[string]string{
+			"queries_total":          "2",
+			"failures_total":         "1",
+			"daily_budget_remaining": "3",
+		} {
+			line := "\nsmallwebwaf_reputation_" + series +
+				`{instance="app",source="abuseipdb"} ` + want + "\n"
+			if !strings.Contains(scraped, line) {
+				t.Errorf("metrics\n%s\nwant%s", scraped, line)
+			}
+		}
+	})
+}
+
+func TestScoreFetchedATTLAgoIsNeitherUsedNorKept(t *testing.T) {
+	t.Parallel()
+
+	now := time.Date(2026, 10, 7, 0, 0, 0, 0, time.UTC)
+	p := abuseIPDBParams()
+	p.Now = func() time.Time { return now }
+	checker := reputation.NewAbuseIPDB(p)
+
+	// The last score still in use, and one, of other's /64, fetched a TTL
+	// ago.
+	inUse := reputation.Score{
+		Client: netip.MustParsePrefix(suspect + "/32"), Score: 100,
+		Fetched: now.Add(-cacheTTL + time.Nanosecond),
+	}
+	stale := reputation.Score{
+		Client: netip.MustParsePrefix("2001:db8::/64"), Score: 100,
+		Fetched: now.Add(-cacheTTL),
+	}
+
+	checker.Load(reputation.Checks{Scores: []reputation.Score{stale, inUse}})
+
+	wantScore(t, checker, suspect, false, 100, true)
+	wantScore(t, checker, other, false, 0, false)
+
+	got := checker.Snapshot().Scores
+	if !reflect.DeepEqual(got, []reputation.Score{inUse}) {
+		t.Errorf("scores %+v, want only %+v", got, inUse)
+	}
+}
+
+func TestAtMost100000ScoresKeptTheOneFetchedLongestAgoDroppedFirst(t *testing.T) {
+	t.Parallel()
+
+	now := time.Date(2026, 10, 7, 0, 0, 0, 0, time.UTC)
+	p := abuseIPDBParams()
+	p.Now = func() time.Time { return now }
+	checker := reputation.NewAbuseIPDB(p)
+
+	// 100,001 scores, listed by client, as reputation.json lists them, each
+	// fetched a millisecond before the one before it: the last is one too
+	// many.
+	const count = 100001
+
+	scores := make([]reputation.Score, 0, count)
+
+	addr := netip.MustParseAddr("198.18.0.0")
+	for i := range count {
+		scores = append(scores, reputation.Score{
+			Client:  netip.PrefixFrom(addr, 32),
+			Fetched: now.Add(-time.Duration(i) * time.Millisecond),
+		})
+		addr = addr.Next()
+	}
+
+	checker.Load(reputation.Checks{Scores: scores})
+
+	got := checker.Snapshot().Scores
+	if len(got) != count-1 || !slices.Contains(got, scores[0]) ||
+		slices.Contains(got, scores[count-1]) {
+		t.Errorf("%d scores kept, want all but the one fetched longest ago", len(got))
+	}
+}
+
+// abuseIPDBStandIn is a stand-in for AbuseIPDB. It answers a check sent
+// with key by the client's score, as scores gives it, 0 for a client it
+// does not give; a check sent with another key with 401; and, while
+// status is not 0, every check with status and body; and while hanging,
+// none at all. It notes each client checked, and the key sent.
+type abuseIPDBStandIn struct {
+	mu      sync.Mutex
+	scores  map[string]int64
+	status  int
+	body    string
+	hanging bool
+	checked []string
+	keys    []string
+}
+
+// RoundTrip has the stand-in answer req, in place of the network. A check
+// abandoned before the stand-in answers fails, as over the network.
+func (s *abuseIPDBStandIn) RoundTrip(req *http.Request) (*http.Response, error) {
+	client := req.URL.Query().Get("ipAddress")
+	sent := req.Header.Get("Key")
+
+	s.mu.Lock()
+	s.checked = append(s.checked, client)
+	s.keys = append(s.keys, sent)
+	score := s.scores[client]
+	status, body, hanging := s.status, s.body, s.hanging
+	s.mu.Unlock()
+
+	switch {
+	case hanging:
+		<-req.Context().Done()
+
+		return nil, req.Context().Err()
+	case sent != key:
+		status = http.StatusUnauthorized
+	case status == 0:
+		status = http.StatusOK
+		body = fmt.Sprintf(`{"data":{"ipAddress":%q,"abuseConfidenceScore":%d}}`, client,
+			score)
+	}
+
+	return &http.Response{
+		StatusCode: status,
+		Status:     fmt.Sprintf("%d %s", status, http.StatusText(status)),
+		Header:     http.Header{},
+		Body:       io.NopCloser(strings.NewReader(body)),
+		Request:    req,
+	}, nil
+}
+
+// setScore has the stand-in give client score.
+func (s *abuseIPDBStandIn) setScore(client string, score int64) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.scores[client] = score
+}
+
+// answerWith has the stand-in answer every check with status and body.
+func (s *abuseIPDBStandIn) answerWith(status int, body string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.status, s.body = status, body
+}
+
+// abuseIPDBParams returns the AbuseIPDBParams of the tests: key, a minimum
+// score of 75, a daily budget of 900, and the cache TTL and timeout of the
+// DNSBL tests, by the bubble's clock, with alerts to a queue that sends
+// none.
+func abuseIPDBParams() reputation.AbuseIPDBParams {
+	return reputation.AbuseIPDBParams{
+		URL:         "https://abuseipdb.example/api/v2/check",
+		Key:         key,
+		MinScore:    75,
+		DailyBudget: 900,
+		CacheTTL:    cacheTTL,
+		Timeout:     timeout,
+		Now:         time.Now,
+		ProcessLog:  slog.New(slog.DiscardHandler),
+		Alerts:      newQueue(),
+	}
+}
+
+// newAbuseIPDB returns the AbuseIPDB of p, checking clients with
+// abuseIPDB.
+func newAbuseIPDB(
+	abuseIPDB *abuseIPDBStandIn, p reputation.AbuseIPDBParams,
+) *reputation.AbuseIPDB {
+	checker := reputation.NewAbuseIPDB(p)
+	checker.SetTransport(abuseIPDB)
+
+	return checker
+}
+
+// wantScore checks the score checker gives client, and whether it is a
+// hit, as a request from client finds them, offender or not.
+func wantScore(
+	t *testing.T, checker *reputation.AbuseIPDB, client string, offender bool,
+	score int64, hit bool,
+) {
+	t.Helper()
+
+	gotScore, gotHit := hitFrom(t, checker, client, offender)
+	if gotScore != score || gotHit != hit {
+		t.Errorf("%s has the score %d, a hit %t, want %d, %t", client, gotScore, gotHit,
+			score, hit)
+	}
+}
+
+// hitFrom is checker's Hit for a request from address, offender or not.
+// Its client is address for an IPv4 address, and its /64 for an IPv6 one,
+// as smallwebwaf counts clients.
+func hitFrom(
+	t *testing.T, checker *reputation.AbuseIPDB, address string, offender bool,
+) (int64, bool) {
+	t.Helper()
+
+	addr := netip.MustParseAddr(address)
+
+	client := netip.PrefixFrom(addr, addr.BitLen())
+	if addr.Is6() {
+		client = netip.PrefixFrom(addr, 64).Masked()
+	}
+
+	return checker.Hit(t.Context(), client, addr, offender)
+}
+
+// wantChecked checks the clients the stand-in was asked about, in any
+// order.
+func wantChecked(t *testing.T, abuseIPDB *abuseIPDBStandIn, want ...string) {
+	t.Helper()
+
+	abuseIPDB.mu.Lock()
+	got := slices.Sorted(slices.Values(abuseIPDB.checked))
+	abuseIPDB.mu.Unlock()
+
+	want = slices.Sorted(slices.Values(want))
+
+	if !slices.Equal(got, want) {
+		t.Errorf("checked %v, want %v", got, want)
+	}
+}
+
+// wantFailures checks how many checks failed.
+func wantFailures(t *testing.T, checker *reputation.AbuseIPDB, want int) {
+	t.Helper()
+
+	if got := checker.Failures(); got != want {
+		t.Errorf("%d checks failed, want %d", got, want)
+	}
+}
+
+// wantFailureAlert checks that the one alert waiting in queue is a
+// source_failure alert from AbuseIPDB, raised at raised, with reason and
+// the error failure, and that the cooldown has held back held repeats of
+// it.
+func wantFailureAlert(
+	t *testing.T, queue *alerts.Queue, raised time.Time, reason, failure string,
+	held int64,
+) {
+	t.Helper()
+
+	got := waiting(queue)
+	if len(got) != 1 || !got[0].Time.Equal(raised) ||
+		got[0].Event != alerts.EventSourceFailure || got[0].Reason != reason ||
+		got[0].Detail["source"] != reputation.AbuseIPDBSource ||
+		got[0].Detail["error"] != failure || queue.Suppressed() != held {
+		t.Errorf("alerts waiting %+v, %d held back, want only AbuseIPDB's %q with %q, "+
+			"and %d", got, queue.Suppressed(), reason, failure, held)
+	}
+}
+
+// wantBudgetLeft checks how many checks the day's budget has left.
+func wantBudgetLeft(t *testing.T, checker *reputation.AbuseIPDB, want int) {
+	t.Helper()
+
+	if got := checker.BudgetLeft(); got != want {
+		t.Errorf("%d checks left, want %d", got, want)
+	}
+}
+
+// scrapeMetrics returns the metrics m serves.
+func scrapeMetrics(t *testing.T, m *metrics.Metrics) string {
+	t.Helper()
+
+	scraped := httptest.NewRecorder()
+	m.ServeHTTP(scraped, httptest.NewRequestWithContext(t.Context(), http.MethodGet, "/",
+		http.NoBody))
+
+	return scraped.Body.String()
+}

internal/reputation/dnsbl.go

@@ -0,0 +1,332 @@
+package reputation
+
+import (
+	"cmp"
+	"context"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"log/slog"
+	"net"
+	"net/netip"
+	"slices"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/hashicorp/golang-lru/v2/simplelru"
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/config"
+)
+
+const (
+	// maxVerdicts is how many verdicts of the DNSBL zones are kept, and how
+	// many scores of AbuseIPDB. Past it, the one fetched longest ago is
+	// dropped.
+	maxVerdicts = 100000
+	// maxQueries is how many queries may be under way at once. Past it, a
+	// zone is not asked about a client until the client's next request, so
+	// that a swarm of new addresses cannot fill the memory.
+	maxQueries = 1000
+	// failureDelay is how long a zone is not asked again after a query to
+	// it fails, and no client is checked with AbuseIPDB after a check
+	// fails, so that a source refusing them is not asked on every request.
+	failureDelay = time.Minute
+)
+
+var (
+	errAsk        = errors.New("ask the zone")
+	errRefused    = errors.New("the zone refused the query")
+	errNotListing = errors.New("the answer is outside 127.0.0.0/8")
+)
+
+// Verdict is what a zone said about a client, as reputation.json holds
+// it: the zone, the client's address, whether the zone lists it, and when
+// the zone answered.
+type Verdict struct {
+	Zone    string     `json:"zone"`
+	Client  netip.Addr `json:"client"`
+	Listed  bool       `json:"listed"`
+	Fetched time.Time  `json:"fetched"`
+}
+
+// DNSBLParams are what NewDNSBL needs.
+type DNSBLParams struct {
+	// Zones are the DNSBL zones clients are asked about in
+	// (SWWAF_DNSBL_ZONES).
+	Zones []string
+	// Resolver is the resolver they are asked through
+	// (SWWAF_DNSBL_RESOLVER), or, while it is the zero AddrPort, the
+	// host's, as /etc/resolv.conf names it.
+	Resolver netip.AddrPort
+	// CacheTTL is how long a verdict is used after it was fetched
+	// (SWWAF_REPUTATION_CACHE_TTL), and Timeout how long a query may take
+	// (SWWAF_REPUTATION_TIMEOUT).
+	CacheTTL time.Duration
+	Timeout  time.Duration
+	// Now tells the time, normally time.Now in UTC.
+	Now func() time.Time
+	// ProcessLog receives each query that fails, and why.
+	ProcessLog *slog.Logger
+	// Alerts receive a source_failure alert for each query that fails.
+	Alerts *alerts.Queue
+}
+
+// DNSBL asks the DNSBL zones about clients, in the background, and keeps
+// their verdicts. It is safe for concurrent use.
+type DNSBL struct {
+	params   DNSBLParams
+	resolver *net.Resolver
+
+	mu sync.Mutex
+	// verdicts are by query. Each is added as it is fetched and never moved
+	// up, so that the one fetched longest ago is the first dropped.
+	verdicts *simplelru.LRU[query, Verdict]
+	// asking are the queries under way.
+	asking map[query]bool
+	// queries and failures count, by zone, the queries made and those that
+	// failed, and retryAt is when a zone whose last query failed may be
+	// asked again.
+	queries  map[string]int
+	failures map[string]int
+	retryAt  map[string]time.Time
+}
+
+// query is a client's address, to ask a zone about.
+type query struct {
+	zone   string
+	client netip.Addr
+}
+
+// NewDNSBL returns a DNSBL with no verdict yet.
+func NewDNSBL(params DNSBLParams) *DNSBL {
+	verdicts, err := simplelru.NewLRU[query, Verdict](maxVerdicts, nil)
+	if err != nil {
+		panic(err) // NewLRU fails only for a size below one
+	}
+
+	resolver := &net.Resolver{}
+	if params.Resolver.IsValid() {
+		// Dial is used by Go's own resolver alone.
+		resolver.PreferGo = true
+		resolver.Dial = func(ctx context.Context, network, _ string) (net.Conn, error) {
+			var dialer net.Dialer
+
+			return dialer.DialContext(ctx, network, params.Resolver.String())
+		}
+	}
+
+	return &DNSBL{
+		params:   params,
+		resolver: resolver,
+		verdicts: verdicts,
+		asking:   map[query]bool{},
+		queries:  map[string]int{},
+		failures: map[string]int{},
+		retryAt:  map[string]time.Time{},
+	}
+}
+
+// Zones returns the zones, in the order SWWAF_DNSBL_ZONES names them.
+func (d *DNSBL) Zones() []string {
+	return slices.Clone(d.params.Zones)
+}
+
+// ListedBy returns the zones whose verdict on addr, a client's address,
+// lists it, in the order SWWAF_DNSBL_ZONES names them, each with its key
+// masked, as config.MaskZoneKey masks it, since they go to the request
+// log, the alerts and the metrics. A verdict is used until CacheTTL has
+// passed since it was fetched. Each zone without one is asked about addr
+// in the background, unless a query about addr to it is under way, the
+// zone is left alone after a failure, or maxQueries are under way;
+// ListedBy never waits for a query. ctx is the context of the client's
+// request, and a query goes on after the request ends.
+func (d *DNSBL) ListedBy(ctx context.Context, addr netip.Addr) []string {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	now := d.params.Now()
+
+	var listedBy []string
+
+	for _, zone := range d.params.Zones {
+		q := query{zone: zone, client: addr}
+
+		kept, found := d.verdicts.Peek(q)
+
+		switch {
+		case found && now.Sub(kept.Fetched) < d.params.CacheTTL:
+			if kept.Listed {
+				listedBy = append(listedBy, config.MaskZoneKey(zone))
+			}
+		case !d.asking[q] && !now.Before(d.retryAt[zone]) && len(d.asking) < maxQueries:
+			d.asking[q] = true
+			d.queries[zone]++
+
+			go d.ask(context.WithoutCancel(ctx), q)
+		}
+	}
+
+	return listedBy
+}
+
+// Queries returns how many queries were made to zone.
+func (d *DNSBL) Queries(zone string) int {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	return d.queries[zone]
+}
+
+// Failures returns how many queries to zone failed.
+func (d *DNSBL) Failures(zone string) int {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	return d.failures[zone]
+}
+
+// Snapshot returns every verdict still in use, sorted by client, then by
+// zone, as reputation.json lists them.
+func (d *DNSBL) Snapshot() []Verdict {
+	d.mu.Lock()
+
+	now := d.params.Now()
+	verdicts := make([]Verdict, 0, d.verdicts.Len())
+
+	for _, kept := range d.verdicts.Values() {
+		if now.Sub(kept.Fetched) < d.params.CacheTTL {
+			verdicts = append(verdicts, kept)
+		}
+	}
+
+	d.mu.Unlock()
+
+	slices.SortFunc(verdicts, func(a, b Verdict) int {
+		return cmp.Or(a.Client.Compare(b.Client), strings.Compare(a.Zone, b.Zone))
+	})
+
+	return verdicts
+}
+
+// Load keeps verdicts, read from reputation.json, in place of those it
+// keeps, but for those of a zone SWWAF_DNSBL_ZONES does not name, and,
+// past maxVerdicts, those fetched longest ago. One fetched CacheTTL ago or
+// more is neither used nor written, as for any verdict.
+func (d *DNSBL) Load(verdicts []Verdict) {
+	verdicts = slices.Clone(verdicts)
+	slices.SortStableFunc(verdicts, func(a, b Verdict) int {
+		return a.Fetched.Compare(b.Fetched)
+	})
+
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	d.verdicts.Purge()
+
+	for _, kept := range verdicts {
+		if slices.Contains(d.params.Zones, kept.Zone) {
+			d.verdicts.Add(query{zone: kept.Zone, client: kept.Client}, kept)
+		}
+	}
+}
+
+// ask asks q's zone about q's client, keeps the verdict, and notes the
+// query as no longer under way. A query that fails gives no verdict: it
+// is counted, logged and raised as a source_failure alert, which show the
+// zone with its key masked, and the zone is not asked again for
+// failureDelay.
+func (d *DNSBL) ask(ctx context.Context, q query) {
+	listed, err := d.lookUp(ctx, q)
+	now := d.params.Now()
+
+	d.mu.Lock()
+
+	delete(d.asking, q)
+
+	if err == nil {
+		d.verdicts.Add(q, Verdict{
+			Zone: q.zone, Client: q.client, Listed: listed, Fetched: now,
+		})
+	} else {
+		d.failures[q.zone]++
+		d.retryAt[q.zone] = now.Add(failureDelay)
+	}
+
+	d.mu.Unlock()
+
+	if err != nil {
+		const failed = "asking a DNSBL zone failed"
+
+		shown := config.MaskZoneKey(q.zone)
+
+		// Raised before it is logged, so that the alert is there once the
+		// log line is.
+		raiseFailure(d.params.Alerts, failed, shown, err)
+		d.params.ProcessLog.Warn(failed, "zone", shown, "error", err.Error())
+	}
+}
+
+// lookUp asks q's zone about q's client through the resolver, and returns
+// whether the zone lists it, as readAnswer reads the answer. No such name
+// is a client the zone does not list. A query not answered within Timeout
+// fails.
+func (d *DNSBL) lookUp(ctx context.Context, q query) (bool, error) {
+	ctx, cancel := context.WithTimeout(ctx, d.params.Timeout)
+	defer cancel()
+
+	answer, err := d.resolver.LookupNetIP(ctx, "ip4", queryName(q.zone, q.client))
+
+	var dnsErr *net.DNSError
+
+	switch {
+	case err == nil:
+		return readAnswer(answer)
+	case errors.As(err, &dnsErr) && dnsErr.IsNotFound:
+		return false, nil
+	case errors.As(err, &dnsErr):
+		// The error names the name asked about, which holds the client's
+		// address, which is not to be logged: only what went wrong is kept.
+		return false, fmt.Errorf("%w: %s", errAsk, dnsErr.Err)
+	default:
+		return false, fmt.Errorf("%w: %w", errAsk, err)
+	}
+}
+
+// queryName returns the name a zone is asked about addr by, as RFC 5782
+// builds it: the four numbers of an IPv4 address, or the 32 hex digits of
+// an IPv6 address, in reverse order, each followed by a dot, then the zone
+// and a dot, which makes it a full name, to which the resolver adds no
+// search domain of /etc/resolv.conf.
+func queryName(zone string, addr netip.Addr) string {
+	parts := strings.Split(addr.String(), ".")
+	if addr.Is6() {
+		parts = strings.Split(hex.EncodeToString(addr.AsSlice()), "")
+	}
+
+	slices.Reverse(parts)
+
+	return strings.Join(parts, ".") + "." + zone + "."
+}
+
+// readAnswer reads the addresses a zone answered with. An address in
+// 127.0.0.0/8 lists the client, as RFC 5782 has zones answer, but one in
+// 127.255.255.0/24 is how Spamhaus refuses a query, such as one sent
+// through a public resolver or one past its limit, and is a failure. So is
+// an address outside 127.0.0.0/8, such as a resolver gives that answers
+// even for names that do not exist.
+func readAnswer(answer []netip.Addr) (bool, error) {
+	listing := netip.MustParsePrefix("127.0.0.0/8")
+	refusal := netip.MustParsePrefix("127.255.255.0/24")
+
+	for _, addr := range answer {
+		switch {
+		case refusal.Contains(addr):
+			return false, fmt.Errorf("%w: %s", errRefused, addr)
+		case !listing.Contains(addr):
+			return false, fmt.Errorf("%w: %s", errNotListing, addr)
+		}
+	}
+
+	return len(answer) > 0, nil
+}

internal/reputation/dnsbl_test.go

@@ -0,0 +1,737 @@
+package reputation_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/binary"
+	"errors"
+	"io"
+	"log/slog"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"net/netip"
+	"reflect"
+	"slices"
+	"strings"
+	"sync"
+	"testing"
+	"testing/synctest"
+	"time"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/metrics"
+	"sneak.berlin/go/smallwebwaf/internal/reputation"
+)
+
+// The tests of the DNSBL zones run in synctest bubbles, as those of the
+// lists do, and the resolver the zones are asked through is a stand-in
+// reached through an in-memory connection, net.Pipe's, for the same
+// reason. They run one at a time, none in parallel with another test of
+// this package: Go's resolver counts the queries under way in one
+// sync.WaitGroup for the whole process, and the process fails when
+// queries from two bubbles, or from a bubble and from outside one, are
+// under way at once. TestMain has the resolver make its configuration,
+// which it makes on its first query, outside every bubble, since the
+// configuration holds a channel, which the bubble it was made in would
+// keep to itself.
+
+const (
+	// zone and otherZone are the DNSBL zones the tests name.
+	zone      = "dnsbl.example"
+	otherZone = "other.example"
+	// cacheTTL is the tests' SWWAF_REPUTATION_CACHE_TTL, and timeout their
+	// SWWAF_REPUTATION_TIMEOUT: a second, the least time /etc/resolv.conf
+	// can have Go's resolver wait for one server, so that it is the
+	// DNSBL's own timeout that ends a query, whatever that file says.
+	cacheTTL = 24 * time.Hour
+	timeout  = time.Second
+	// listed and unlisted are clients zone is asked about by the names
+	// listedName and unlistedName, and most tests have zone list the first
+	// alone, by answering with listing.
+	listed       = "192.0.2.99"
+	unlisted     = "192.0.2.100"
+	listedName   = "99.2.0.192." + zone + "."
+	unlistedName = "100.2.0.192." + zone + "."
+	listing      = "127.0.0.2"
+)
+
+// The DNS response codes the stand-in answers with, besides no error.
+const (
+	serverFailure = 2
+	noSuchName    = 3
+	refused       = 5
+)
+
+var errNoNetwork = errors.New("the test dials nothing")
+
+func TestMain(m *testing.M) {
+	// A query that fails at once, as nothing is dialled for it.
+	resolver := &net.Resolver{
+		PreferGo: true,
+		Dial: func(context.Context, string, string) (net.Conn, error) {
+			return nil, errNoNetwork
+		},
+	}
+	_, _ = resolver.LookupNetIP(context.Background(), "ip4", "warm-up.invalid.")
+
+	m.Run()
+}
+
+//nolint:paralleltest // one at a time, as the comment at the top of this file says
+func TestZonesListOrNotClientsByTheirIPv4AndIPv6Addresses(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
+		// The addresses of the examples of RFC 5782, and the names it
+		// gives for them.
+		const (
+			v4 = "192.0.2.99"
+			v6 = "2001:db8:1:2:3:4:567:89ab"
+			// v6Name is the hex digits of v6, in reverse order.
+			v6Name = "b.a.9.8.7.6.5.0.4.0.0.0.3.0.0.0.2.0.0.0.1.0.0.0.8.b.d.0.1.0.0.2."
+		)
+
+		resolver := &resolverStandIn{answers: map[string]answer{
+			"99.2.0.192." + zone + ".":      {addrs: []string{listing}},
+			v6Name + otherZone + ".":        {addrs: []string{"127.0.0.4", "127.0.0.10"}},
+			"99.2.0.192." + otherZone + ".": {},
+		}}
+		dnsbl := newDNSBL(resolver, dnsblParams(zone, otherZone))
+
+		// Neither client has a verdict yet, so neither is listed, and each
+		// zone is asked about each.
+		wantZones(t, dnsbl, v4)
+		wantZones(t, dnsbl, v6)
+		synctest.Wait()
+
+		wantZones(t, dnsbl, v4, zone)
+		wantZones(t, dnsbl, v6, otherZone)
+		wantAsked(t, resolver,
+			"99.2.0.192."+zone+".", "99.2.0.192."+otherZone+".",
+			v6Name+zone+".", v6Name+otherZone+".")
+	})
+}
+
+//nolint:paralleltest // one at a time, as the comment at the top of this file says
+func TestListedByNeverWaitsForAQuery(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
+		dnsbl := newDNSBL(&resolverStandIn{hanging: true}, dnsblParams(zone))
+		began := time.Now()
+
+		// The second, while the first's query is under way, starts none.
+		wantZones(t, dnsbl, listed)
+		wantZones(t, dnsbl, listed)
+
+		if waited := time.Since(began); waited != 0 {
+			t.Errorf("waited %s for the query, want no wait", waited)
+		}
+
+		synctest.Wait()
+		wantQueries(t, dnsbl, 1, 0)
+		waitForTheResolver()
+	})
+}
+
+//nolint:paralleltest // one at a time, as the comment at the top of this file says
+func TestVerdictUsedUntilTheCacheTTLHasPassedSinceItWasFetched(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
+		resolver := &resolverStandIn{answers: map[string]answer{
+			listedName: {addrs: []string{listing}},
+		}}
+		dnsbl := newDNSBL(resolver, dnsblParams(zone))
+
+		wantZones(t, dnsbl, listed)
+		wantZones(t, dnsbl, unlisted)
+		synctest.Wait()
+
+		// The zone lists the other client from now on, but the verdicts
+		// kept are used, and the zone is not asked again, until the TTL
+		// has passed.
+		resolver.set(listedName, answer{rcode: noSuchName})
+		resolver.set(unlistedName, answer{addrs: []string{listing}})
+		time.Sleep(cacheTTL - time.Nanosecond)
+
+		wantZones(t, dnsbl, listed, zone)
+		wantZones(t, dnsbl, unlisted)
+		synctest.Wait()
+		wantQueries(t, dnsbl, 2, 0)
+
+		// Then neither verdict is used, and both clients are asked about
+		// again.
+		time.Sleep(time.Nanosecond)
+		wantZones(t, dnsbl, listed)
+		wantZones(t, dnsbl, unlisted)
+		synctest.Wait()
+
+		wantQueries(t, dnsbl, 4, 0)
+		wantZones(t, dnsbl, listed)
+		wantZones(t, dnsbl, unlisted, zone)
+	})
+}
+
+//nolint:paralleltest // one at a time, as the comment at the top of this file says
+func TestQueryNotAnsweredWithinTheTimeoutFails(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
+		queue := newQueue()
+		p := dnsblParams(zone)
+		p.Alerts = queue
+		dnsbl := newDNSBL(&resolverStandIn{hanging: true}, p)
+
+		wantZones(t, dnsbl, listed)
+		time.Sleep(timeout - time.Nanosecond)
+		synctest.Wait()
+		wantQueries(t, dnsbl, 1, 0)
+
+		time.Sleep(time.Nanosecond)
+		synctest.Wait()
+		wantQueries(t, dnsbl, 1, 1)
+
+		if got := waiting(queue); len(got) != 1 ||
+			got[0].Detail["error"] != "ask the zone: i/o timeout" {
+			t.Errorf("alerts waiting %+v, want the timeout's", got)
+		}
+
+		if verdicts := dnsbl.Snapshot(); len(verdicts) != 0 {
+			t.Errorf("verdicts %+v, want none", verdicts)
+		}
+
+		waitForTheResolver()
+	})
+}
+
+//nolint:paralleltest // one at a time, as the comment at the top of this file says
+func TestZoneThatFailsOrRefusesGivesNoVerdictAndIsLeftAloneForAMinute(t *testing.T) {
+	for _, tc := range []struct {
+		name   string
+		answer answer
+		error  string
+	}{
+		{
+			"a server failure", answer{rcode: serverFailure},
+			"ask the zone: server misbehaving",
+		},
+		{"a refusal", answer{rcode: refused}, "ask the zone: server misbehaving"},
+		{
+			"an answer in 127.255.255.0/24, with which Spamhaus refuses a query",
+			answer{addrs: []string{"127.255.255.254"}},
+			"the zone refused the query: 127.255.255.254",
+		},
+		{
+			"an answer outside 127.0.0.0/8, as for a name that does not exist",
+			answer{addrs: []string{"192.0.2.1"}},
+			"the answer is outside 127.0.0.0/8: 192.0.2.1",
+		},
+	} {
+		//nolint:paralleltest // one at a time, as the comment at the top of this file says
+		t.Run(tc.name, func(t *testing.T) {
+			synctest.Test(t, func(t *testing.T) {
+				var log bytes.Buffer
+
+				queue := newQueue()
+				p := dnsblParams(zone)
+				p.Alerts = queue
+				p.ProcessLog = slog.New(slog.NewJSONHandler(&log, nil))
+				dnsbl := newDNSBL(&resolverStandIn{answers: map[string]answer{
+					listedName: tc.answer,
+				}}, p)
+
+				// The failure gives no verdict, and the zone is not asked
+				// again within a minute of it.
+				wantZones(t, dnsbl, listed)
+				synctest.Wait()
+				time.Sleep(time.Minute - time.Nanosecond)
+				wantZones(t, dnsbl, listed)
+				synctest.Wait()
+				wantQueries(t, dnsbl, 1, 1)
+
+				time.Sleep(time.Nanosecond)
+				wantZones(t, dnsbl, listed)
+				synctest.Wait()
+				wantQueries(t, dnsbl, 2, 2)
+
+				if verdicts := dnsbl.Snapshot(); len(verdicts) != 0 {
+					t.Errorf("verdicts %+v, want none", verdicts)
+				}
+
+				// One alert for the first failure; the cooldown holds back
+				// the second.
+				wantAlert(t, queue, alerts.Alert{
+					Time:   time.Now().Add(-time.Minute),
+					Event:  alerts.EventSourceFailure,
+					Reason: "asking a DNSBL zone failed",
+					Detail: map[string]any{"source": zone, "error": tc.error},
+				})
+
+				if !strings.Contains(log.String(), `"msg":"asking a DNSBL zone failed",`+
+					`"zone":"`+zone+`","error":"`+tc.error) {
+					t.Errorf("logged\n%s\nwant the failures", log.String())
+				}
+			})
+		})
+	}
+}
+
+//nolint:paralleltest // one at a time, as the comment at the top of this file says
+func TestAtMost1000QueriesUnderWay(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
+		dnsbl := newDNSBL(&resolverStandIn{hanging: true}, dnsblParams(zone))
+
+		client := netip.MustParseAddr("198.18.0.0")
+		for range 1001 {
+			dnsbl.ListedBy(t.Context(), client)
+			client = client.Next()
+		}
+
+		synctest.Wait()
+		wantQueries(t, dnsbl, 1000, 0)
+		waitForTheResolver()
+	})
+}
+
+//nolint:paralleltest // one at a time, as the comment at the top of this file says
+func TestMetricsCountEachZonesQueriesAndThoseThatFailed(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
+		resolver := &resolverStandIn{answers: map[string]answer{
+			listedName:                      {addrs: []string{listing}},
+			"99.2.0.192." + otherZone + ".": {rcode: serverFailure},
+		}}
+		dnsbl := newDNSBL(resolver, dnsblParams(zone, otherZone))
+		m := metrics.New(1, "app")
+		m.AddReputation(reputation.New(params()), dnsbl)
+
+		wantZones(t, dnsbl, listed)
+		synctest.Wait()
+
+		scraped := httptest.NewRecorder()
+		m.ServeHTTP(scraped, httptest.NewRequestWithContext(t.Context(), http.MethodGet,
+			"/", http.NoBody))
+
+		for series, want := range map[string]string{
+			"queries_total" + `{instance="app",source="` + zone + `"}`:       "1",
+			"failures_total" + `{instance="app",source="` + zone + `"}`:      "0",
+			"queries_total" + `{instance="app",source="` + otherZone + `"}`:  "1",
+			"failures_total" + `{instance="app",source="` + otherZone + `"}`: "1",
+		} {
+			line := "\nsmallwebwaf_reputation_" + series + " " + want + "\n"
+			if !strings.Contains(scraped.Body.String(), line) {
+				t.Errorf("metrics\n%s\nwant%s", scraped.Body.String(), line)
+			}
+		}
+	})
+}
+
+//nolint:paralleltest // one at a time, as the comment at the top of this file says
+func TestZoneKeyIsMaskedInTheVerdictsTheFailuresAndTheMetrics(t *testing.T) {
+	const (
+		key    = "abcdefghijklmnopqrstuvwxyz"
+		keyed  = key + ".xbl.dq.spamhaus.net"
+		masked = "********.xbl.dq.spamhaus.net"
+	)
+
+	synctest.Test(t, func(t *testing.T) {
+		var log bytes.Buffer
+
+		queue := newQueue()
+		p := dnsblParams(keyed)
+		p.Alerts = queue
+		p.ProcessLog = slog.New(slog.NewJSONHandler(&log, nil))
+		dnsbl := newDNSBL(&resolverStandIn{answers: map[string]answer{
+			"99.2.0.192." + keyed + ".":  {addrs: []string{listing}},
+			"100.2.0.192." + keyed + ".": {rcode: serverFailure},
+		}}, p)
+		m := metrics.New(1, "app")
+		m.AddReputation(reputation.New(params()), dnsbl)
+
+		// Both clients are asked about before either answer comes, so that
+		// the failure does not keep the zone from the other query.
+		wantZones(t, dnsbl, listed)
+		wantZones(t, dnsbl, unlisted)
+		synctest.Wait()
+		wantZones(t, dnsbl, listed, masked)
+
+		if got := waiting(queue); len(got) != 1 || got[0].Detail["source"] != masked {
+			t.Errorf("alerts waiting %+v, want the failure's, from %s", got, masked)
+		}
+
+		scraped := httptest.NewRecorder()
+		m.ServeHTTP(scraped, httptest.NewRequestWithContext(t.Context(), http.MethodGet,
+			"/", http.NoBody))
+
+		for name, shown := range map[string]string{
+			"the log": log.String(), "the metrics": scraped.Body.String(),
+		} {
+			if strings.Contains(shown, key) || !strings.Contains(shown, masked) {
+				t.Errorf("%s shows the key, or does not name the zone:\n%s", name, shown)
+			}
+		}
+	})
+}
+
+//nolint:paralleltest // one at a time, as the comment at the top of this file says
+func TestVerdictsKeptAcrossARestart(t *testing.T) {
+	synctest.Test(t, func(t *testing.T) {
+		resolver := &resolverStandIn{answers: map[string]answer{
+			listedName: {addrs: []string{listing}},
+		}}
+		dnsbl := newDNSBL(resolver, dnsblParams(zone))
+		fetched := time.Now()
+
+		wantZones(t, dnsbl, unlisted)
+		wantZones(t, dnsbl, listed)
+		synctest.Wait()
+
+		kept := dnsbl.Snapshot()
+
+		want := []reputation.Verdict{
+			{Zone: zone, Client: netip.MustParseAddr(listed), Listed: true, Fetched: fetched},
+			{Zone: zone, Client: netip.MustParseAddr(unlisted), Fetched: fetched},
+		}
+		if !reflect.DeepEqual(kept, want) {
+			t.Errorf("verdicts %+v, want %+v", kept, want)
+		}
+
+		// Restarted an hour later with what reputation.json keeps, it uses
+		// the verdicts, and asks the zone nothing, until the TTL has passed
+		// since they were fetched.
+		time.Sleep(time.Hour)
+
+		restarted := &resolverStandIn{}
+		again := newDNSBL(restarted, dnsblParams(zone))
+		again.Load(kept)
+
+		wantZones(t, again, listed, zone)
+		wantZones(t, again, unlisted)
+		synctest.Wait()
+		wantAsked(t, restarted)
+
+		time.Sleep(cacheTTL - time.Hour)
+		wantZones(t, again, listed)
+		synctest.Wait()
+		wantAsked(t, restarted, listedName)
+	})
+}
+
+func TestNeitherAVerdictOfAZoneNotNamedNorOnePastItsTTLIsKept(t *testing.T) {
+	t.Parallel()
+
+	now := time.Date(2026, 10, 7, 0, 0, 0, 0, time.UTC)
+	p := dnsblParams(zone)
+	p.Now = func() time.Time { return now }
+	dnsbl := reputation.NewDNSBL(p)
+
+	// The last verdict still in use, one fetched a TTL ago, and one of a
+	// zone SWWAF_DNSBL_ZONES does not name.
+	inUse := reputation.Verdict{
+		Zone: zone, Client: netip.MustParseAddr(listed), Listed: true,
+		Fetched: now.Add(-cacheTTL + time.Nanosecond),
+	}
+	stale := reputation.Verdict{
+		Zone: zone, Client: netip.MustParseAddr(unlisted), Fetched: now.Add(-cacheTTL),
+	}
+	notNamed := reputation.Verdict{
+		Zone: otherZone, Client: netip.MustParseAddr(listed), Listed: true, Fetched: now,
+	}
+
+	dnsbl.Load([]reputation.Verdict{notNamed, stale, inUse})
+
+	if got := dnsbl.Snapshot(); !reflect.DeepEqual(got, []reputation.Verdict{inUse}) {
+		t.Errorf("verdicts %+v, want only %+v", got, inUse)
+	}
+}
+
+func TestAtMost100000VerdictsKeptTheOneFetchedLongestAgoDroppedFirst(t *testing.T) {
+	t.Parallel()
+
+	now := time.Date(2026, 10, 7, 0, 0, 0, 0, time.UTC)
+	p := dnsblParams(zone)
+	p.Now = func() time.Time { return now }
+	dnsbl := reputation.NewDNSBL(p)
+
+	// 100,001 verdicts, listed by client, as reputation.json lists them,
+	// each fetched a millisecond before the one before it: the last is one
+	// too many.
+	const count = 100001
+
+	verdicts := make([]reputation.Verdict, 0, count)
+
+	client := netip.MustParseAddr("198.18.0.0")
+	for i := range count {
+		verdicts = append(verdicts, reputation.Verdict{
+			Zone: zone, Client: client, Fetched: now.Add(-time.Duration(i) * time.Millisecond),
+		})
+		client = client.Next()
+	}
+
+	dnsbl.Load(verdicts)
+
+	got := dnsbl.Snapshot()
+	if len(got) != count-1 || !slices.Contains(got, verdicts[0]) ||
+		slices.Contains(got, verdicts[count-1]) {
+		t.Errorf("%d verdicts kept, want all but the one fetched longest ago", len(got))
+	}
+}
+
+//nolint:paralleltest // one at a time, as the comment at the top of this file says
+func TestQueriesGoToTheResolverSWWAFDNSBLResolverNames(t *testing.T) {
+	resolver := &resolverStandIn{answers: map[string]answer{
+		listedName: {addrs: []string{listing}},
+	}}
+
+	conn, err := (&net.ListenConfig{}).ListenPacket(t.Context(), "udp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("listen: %v", err)
+	}
+
+	served := make(chan struct{})
+
+	go func() {
+		resolver.serveUDP(conn)
+		close(served)
+	}()
+
+	t.Cleanup(func() {
+		_ = conn.Close()
+
+		<-served
+	})
+
+	p := dnsblParams(zone)
+	p.Resolver = netip.MustParseAddrPort(conn.LocalAddr().String())
+	// On the real clock: the stand-in answers at once, so only a test
+	// process held up for a whole minute would see the query fail.
+	p.Timeout = time.Minute
+
+	isListed, err := reputation.NewDNSBL(p).LookUp(zone, netip.MustParseAddr(listed))
+	if err != nil || !isListed {
+		t.Errorf("listed %t (%v), want true", isListed, err)
+	}
+
+	wantAsked(t, resolver, listedName)
+}
+
+// resolverStandIn is a stand-in for the resolver the zones are asked
+// through. It answers each query by the name asked about, as answers
+// gives, with no such name for a name answers does not give, and not at
+// all while hanging. It notes each name asked about.
+type resolverStandIn struct {
+	mu      sync.Mutex
+	answers map[string]answer
+	hanging bool
+	names   []string
+}
+
+// answer is how the stand-in answers a name: with an A record of each of
+// addrs, or with the response code rcode, unless it is 0, for no error.
+type answer struct {
+	addrs []string
+	rcode uint16
+}
+
+// What the stand-in reads of a query, and writes in its reply.
+const (
+	// headerLength is the length of a DNS message's header, which the
+	// question follows: its id, its flags, and how many questions,
+	// answers and other records it holds, two bytes each.
+	headerLength = 12
+	// typeAndClass is the length of the type and the class that end a
+	// question, after its name.
+	typeAndClass = 4
+	// replyFlags mark a reply to a query that asked for recursion, which
+	// is available, with no error. The response code goes in their last
+	// four bits.
+	replyFlags = 0x8180
+	// maxMessage is the longest query read over UDP.
+	maxMessage = 1232
+)
+
+// set has the stand-in answer name with given.
+func (s *resolverStandIn) set(name string, given answer) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.answers[name] = given
+}
+
+// dial connects Go's resolver to the stand-in through an in-memory
+// connection, on which it sends each query, and reads each reply, after
+// its length, as over TCP.
+func (s *resolverStandIn) dial(context.Context, string, string) (net.Conn, error) {
+	client, server := net.Pipe()
+
+	go s.serve(server)
+
+	return client, nil
+}
+
+// serve answers the queries that come on conn until the resolver closes
+// it.
+func (s *resolverStandIn) serve(conn net.Conn) {
+	defer func() {
+		_ = conn.Close()
+	}()
+
+	for {
+		var length [2]byte
+
+		_, err := io.ReadFull(conn, length[:])
+		if err != nil {
+			return
+		}
+
+		message := make([]byte, binary.BigEndian.Uint16(length[:]))
+
+		_, err = io.ReadFull(conn, message)
+		if err != nil {
+			return
+		}
+
+		reply, answered := s.reply(message)
+		if !answered {
+			continue // the resolver gives up, and closes conn
+		}
+
+		//nolint:gosec // a reply of a few dozen bytes
+		_, err = conn.Write(append(binary.BigEndian.AppendUint16(nil, uint16(len(reply))),
+			reply...))
+		if err != nil {
+			return
+		}
+	}
+}
+
+// serveUDP answers the queries that come on conn, each in a datagram, as
+// a resolver does, until conn is closed.
+func (s *resolverStandIn) serveUDP(conn net.PacketConn) {
+	message := make([]byte, maxMessage)
+
+	for {
+		n, from, err := conn.ReadFrom(message)
+		if err != nil {
+			return
+		}
+
+		reply, answered := s.reply(message[:n])
+		if answered {
+			_, _ = conn.WriteTo(reply, from)
+		}
+	}
+}
+
+// reply returns the stand-in's reply to message, a query, and false for
+// none, while it hangs. It notes the name asked about.
+func (s *resolverStandIn) reply(message []byte) ([]byte, bool) {
+	// The name is labels, each after its length, ended by a length of 0.
+	var labels []string
+
+	end := headerLength
+	for message[end] != 0 {
+		length := int(message[end])
+		labels = append(labels, string(message[end+1:end+1+length]))
+		end += 1 + length
+	}
+
+	end += 1 + typeAndClass
+	name := strings.Join(labels, ".") + "."
+
+	s.mu.Lock()
+	s.names = append(s.names, name)
+	given, found := s.answers[name]
+	hanging := s.hanging
+	s.mu.Unlock()
+
+	if hanging {
+		return nil, false
+	}
+
+	if !found {
+		given = answer{rcode: noSuchName}
+	}
+
+	// The query's id, the flags, one question, the answers, and no other
+	// records, then the question, as asked.
+	reply := slices.Clone(message[:2])
+	reply = binary.BigEndian.AppendUint16(reply, replyFlags|given.rcode)
+	reply = binary.BigEndian.AppendUint16(reply, 1)
+	//nolint:gosec // a handful of answers
+	reply = binary.BigEndian.AppendUint16(reply, uint16(len(given.addrs)))
+	reply = append(reply, 0, 0, 0, 0)
+	reply = append(reply, message[headerLength:end]...)
+
+	// An A record starts with the name asked about, by a pointer to it in
+	// the question, then its type, A, its class, IN, how long it may be
+	// kept, 60 seconds, and the length of its address, 4 bytes.
+	record := []byte{0xc0, headerLength, 0, 1, 0, 1, 0, 0, 0, 60, 0, 4}
+
+	for _, addr := range given.addrs {
+		reply = append(reply, record...)
+		reply = append(reply, netip.MustParseAddr(addr).AsSlice()...)
+	}
+
+	return reply, true
+}
+
+// dnsblParams returns the DNSBLParams of zones, with the tests' cache TTL
+// and timeout, by the bubble's clock, with alerts to a queue that sends
+// none.
+func dnsblParams(zones ...string) reputation.DNSBLParams {
+	return reputation.DNSBLParams{
+		Zones:      zones,
+		CacheTTL:   cacheTTL,
+		Timeout:    timeout,
+		Now:        time.Now,
+		ProcessLog: slog.New(slog.DiscardHandler),
+		Alerts:     newQueue(),
+	}
+}
+
+// waitForTheResolver waits, on the bubble's clock, an hour, until Go's
+// resolver has given up on every stand-in that does not answer: it waits
+// for a server as long as /etc/resolv.conf has it wait, a few seconds,
+// even after the query was given up, and a bubble cannot end before it.
+func waitForTheResolver() {
+	time.Sleep(time.Hour)
+}
+
+// newDNSBL returns the DNSBL of p, asking resolver.
+func newDNSBL(resolver *resolverStandIn, p reputation.DNSBLParams) *reputation.DNSBL {
+	dnsbl := reputation.NewDNSBL(p)
+	dnsbl.SetDial(resolver.dial)
+
+	return dnsbl
+}
+
+// wantZones checks the zones whose verdict dnsbl says lists client, as a
+// request from client finds them.
+func wantZones(t *testing.T, dnsbl *reputation.DNSBL, client string, want ...string) {
+	t.Helper()
+
+	got := dnsbl.ListedBy(t.Context(), netip.MustParseAddr(client))
+	if !slices.Equal(got, want) {
+		t.Errorf("%s is listed by %v, want %v", client, got, want)
+	}
+}
+
+// wantQueries checks how many queries dnsbl made to zone, and how many of
+// them failed.
+func wantQueries(t *testing.T, dnsbl *reputation.DNSBL, queries, failures int) {
+	t.Helper()
+
+	if dnsbl.Queries(zone) != queries || dnsbl.Failures(zone) != failures {
+		t.Errorf("%d queries and %d failures, want %d and %d", dnsbl.Queries(zone),
+			dnsbl.Failures(zone), queries, failures)
+	}
+}
+
+// wantAsked checks the names the stand-in was asked about, in any order.
+func wantAsked(t *testing.T, resolver *resolverStandIn, want ...string) {
+	t.Helper()
+
+	resolver.mu.Lock()
+	got := slices.Sorted(slices.Values(resolver.names))
+	resolver.mu.Unlock()
+
+	slices.Sort(want)
+
+	if !slices.Equal(got, want) {
+		t.Errorf("asked about %v, want %v", got, want)
+	}
+}

internal/reputation/export_test.go

@@ -0,0 +1,33 @@
+package reputation
+
+import (
+	"context"
+	"net"
+	"net/http"
+	"net/netip"
+)
+
+// SetTransport has l's fetches go through transport instead of the
+// network.
+func (l *Lists) SetTransport(transport http.RoundTripper) {
+	l.httpClient.Transport = transport
+}
+
+// SetTransport has a's checks go through transport instead of the
+// network.
+func (a *AbuseIPDB) SetTransport(transport http.RoundTripper) {
+	a.httpClient.Transport = transport
+}
+
+// SetDial has d's queries go through dial instead of the network.
+func (d *DNSBL) SetDial(
+	dial func(ctx context.Context, network, address string) (net.Conn, error),
+) {
+	d.resolver = &net.Resolver{PreferGo: true, Dial: dial}
+}
+
+// LookUp asks zone about addr at once, as a query in the background does,
+// and returns whether zone lists addr.
+func (d *DNSBL) LookUp(zone string, addr netip.Addr) (bool, error) {
+	return d.lookUp(context.Background(), query{zone: zone, client: addr})
+}

internal/reputation/reputation.go

@@ -0,0 +1,509 @@
+// Package reputation fetches the lists the settings name by URL: the
+// blocklists of SWWAF_BLOCKLIST_URLS, and the file of AS:percent lines
+// SWWAF_ASN_LIMIT_PERCENT_URL names. It keeps the last good copy of each,
+// whole, comment lines included, which is used while a fetch fails, and
+// when each was last tried. It also asks the DNSBL zones of
+// SWWAF_DNSBL_ZONES about clients, and keeps their verdicts, and checks
+// clients with AbuseIPDB, and keeps their scores and the checks spent
+// today. The state package writes all of these to reputation.json and
+// reads them from it, so that a restart keeps them too.
+package reputation
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/netip"
+	"slices"
+	"strings"
+	"sync"
+	"time"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/config"
+)
+
+const (
+	// maxListBytes is the most of a list that is read. A longer one is a
+	// failure, so that a wrong URL cannot fill the memory.
+	maxListBytes = 16 << 20
+	// fetchTimeout bounds one fetch of a list.
+	fetchTimeout = time.Minute
+	// mappedBits is the length of ::ffff:0.0.0.0/96, the netblock of every
+	// IPv4-mapped address.
+	mappedBits = 96
+)
+
+var (
+	errStatus        = errors.New("the server answered")
+	errTooLong       = errors.New("the list is longer than 16 MiB")
+	errNotNetblock   = errors.New("is not an address or a netblock, such as 192.0.2.0/24")
+	errNotASNPercent = errors.New(
+		"is not an AS number, : and a percentage, such as AS64496:50")
+)
+
+// List is a list as reputation.json holds it: the URL it is fetched from,
+// when it was last tried, the fetch failed or not, and its last good copy:
+// when that was fetched, and its lines, as fetched, comment lines
+// included, both left out while no fetch of it has succeeded.
+type List struct {
+	URL     string    `json:"url"`
+	Tried   time.Time `json:"tried"`
+	Fetched time.Time `json:"fetched,omitzero"`
+	Lines   []string  `json:"lines,omitzero"`
+}
+
+// Params are what New needs.
+type Params struct {
+	// BlocklistURLs are the blocklists (SWWAF_BLOCKLIST_URLS), and
+	// ASNLimitPercentURL the file of AS:percent lines
+	// (SWWAF_ASN_LIMIT_PERCENT_URL), "" while it is unset.
+	BlocklistURLs      []string
+	ASNLimitPercentURL string
+	// Refresh is how long after a list was last fetched or tried it is
+	// fetched again (SWWAF_BLOCKLIST_REFRESH).
+	Refresh time.Duration
+	// Now tells the time, normally time.Now in UTC.
+	Now func() time.Time
+	// ProcessLog receives each fetch of a list, and why one failed.
+	ProcessLog *slog.Logger
+	// Alerts receive a source_failure alert for each fetch that fails.
+	Alerts *alerts.Queue
+}
+
+// Lists are the lists Params names, each with its last good copy. They
+// are safe for concurrent use.
+type Lists struct {
+	params     Params
+	httpClient *http.Client
+
+	mu sync.Mutex
+	// lists are by URL, one for each URL Params names.
+	lists map[string]*list
+}
+
+// list is one list: what reputation.json keeps of it, its last try, zero
+// before the first, and its last good copy, what that copy says, and how
+// many fetches of it failed.
+type list struct {
+	kept     List
+	entries  entries
+	failures int
+}
+
+// entries are what the lines of a copy say: for a blocklist, the netblocks
+// it names, with the lengths among them, and for the file of AS:percent
+// lines, the percentage it gives each AS number.
+type entries struct {
+	netblocks map[netip.Prefix]bool
+	lengths   []int
+	percents  map[string]int64
+}
+
+// New returns the lists, without a copy of any yet.
+func New(params Params) *Lists {
+	l := &Lists{params: params, httpClient: &http.Client{}, lists: map[string]*list{}}
+
+	for _, listURL := range l.URLs() {
+		l.lists[listURL] = &list{kept: List{URL: listURL}}
+	}
+
+	return l
+}
+
+// URLs returns the URL of every list: the blocklists' in the order
+// SWWAF_BLOCKLIST_URLS names them, then SWWAF_ASN_LIMIT_PERCENT_URL.
+func (l *Lists) URLs() []string {
+	urls := slices.Clone(l.params.BlocklistURLs)
+	if l.params.ASNLimitPercentURL != "" {
+		urls = append(urls, l.params.ASNLimitPercentURL)
+	}
+
+	return urls
+}
+
+// ListedBy returns the URLs of the blocklists whose copy lists addr, in
+// the order SWWAF_BLOCKLIST_URLS names them.
+func (l *Lists) ListedBy(addr netip.Addr) []string {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	var listedBy []string
+
+	for _, listURL := range l.params.BlocklistURLs {
+		if l.lists[listURL].entries.contain(addr) {
+			listedBy = append(listedBy, listURL)
+		}
+	}
+
+	return listedBy
+}
+
+// ASNLimitPercent returns the percentage the copy of the file of
+// AS:percent lines gives asn, and whether it lists asn.
+func (l *Lists) ASNLimitPercent(asn string) (int64, bool) {
+	if l.params.ASNLimitPercentURL == "" {
+		return 0, false
+	}
+
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	percent, listed := l.lists[l.params.ASNLimitPercentURL].entries.percents[asn]
+
+	return percent, listed
+}
+
+// Fetched returns when the copy in use of the list at listURL was
+// fetched, or zero while there is none.
+func (l *Lists) Fetched(listURL string) time.Time {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	return l.lists[listURL].kept.Fetched
+}
+
+// Failures returns how many fetches of the list at listURL failed.
+func (l *Lists) Failures(listURL string) int {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	return l.lists[listURL].failures
+}
+
+// Run fetches each list once Refresh has passed since it was last fetched
+// or tried, the later of the two, until ctx is done. A list never tried is
+// fetched at once, and so is one whose last try or copy, read from
+// reputation.json, is that old.
+func (l *Lists) Run(ctx context.Context) {
+	if len(l.lists) == 0 {
+		return
+	}
+
+	for ctx.Err() == nil {
+		next := l.fetchDue(ctx)
+		timer := time.NewTimer(next.Sub(l.params.Now()))
+
+		select {
+		case <-ctx.Done():
+		case <-timer.C:
+		}
+
+		timer.Stop()
+	}
+}
+
+// Snapshot returns each list that has been tried, with its copy, if it
+// has one, sorted by URL, as reputation.json lists them.
+func (l *Lists) Snapshot() []List {
+	l.mu.Lock()
+
+	tried := make([]List, 0, len(l.lists))
+
+	for _, held := range l.lists {
+		if !held.kept.Tried.IsZero() {
+			tried = append(tried, held.kept)
+		}
+	}
+
+	l.mu.Unlock()
+
+	slices.SortFunc(tried, func(a, b List) int {
+		return strings.Compare(a.URL, b.URL)
+	})
+
+	return tried
+}
+
+// Load puts lists, read from reputation.json, in place of the last tries
+// and copies held. A list Params does not name is dropped. A copy with a
+// line that parse refuses is an error, and then nothing changes.
+func (l *Lists) Load(lists []List) error {
+	found := make(map[string]entries, len(lists))
+
+	for _, kept := range lists {
+		if _, named := l.lists[kept.URL]; !named {
+			continue
+		}
+
+		read, err := l.parse(kept.URL, kept.Lines)
+		if err != nil {
+			return fmt.Errorf("the copy of %s: %w", kept.URL, err)
+		}
+
+		found[kept.URL] = read
+	}
+
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	for listURL, held := range l.lists {
+		held.kept, held.entries = List{URL: listURL}, entries{}
+	}
+
+	for _, kept := range lists {
+		read, named := found[kept.URL]
+		if named {
+			l.lists[kept.URL].kept, l.lists[kept.URL].entries = kept, read
+		}
+	}
+
+	return nil
+}
+
+// fetchDue fetches each list that is due, one after another, and returns
+// when the next is due. Once ctx has ended, it starts none, since a fetch
+// cut off is noted as a try.
+func (l *Lists) fetchDue(ctx context.Context) time.Time {
+	var next time.Time
+
+	for _, listURL := range l.URLs() {
+		due := l.due(listURL)
+		if ctx.Err() == nil && !l.params.Now().Before(due) {
+			l.fetch(ctx, listURL)
+			due = l.due(listURL)
+		}
+
+		if next.IsZero() || due.Before(next) {
+			next = due
+		}
+	}
+
+	return next
+}
+
+// due returns when the list at listURL is to be fetched: Refresh after it
+// was last fetched or tried, the later of the two.
+func (l *Lists) due(listURL string) time.Time {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	held := l.lists[listURL]
+
+	last := held.kept.Fetched
+	if held.kept.Tried.After(last) {
+		last = held.kept.Tried
+	}
+
+	return last.Add(l.params.Refresh)
+}
+
+// fetch fetches the list at listURL, and notes the try. A good copy takes
+// the place of the one held. A failure leaves that in use, and is counted,
+// logged and raised as a source_failure alert. A fetch cut off as ctx
+// ends, as smallwebwaf stops, is no failure, but is still noted as a try,
+// so that a restart waits for it: the server may have had its request.
+func (l *Lists) fetch(ctx context.Context, listURL string) {
+	lines, err := l.get(ctx, listURL)
+
+	var found entries
+	if err == nil {
+		found, err = l.parse(listURL, lines)
+	}
+
+	cutOff := err != nil && ctx.Err() != nil
+	now := l.params.Now()
+
+	l.mu.Lock()
+
+	held := l.lists[listURL]
+	held.kept.Tried = now
+
+	if err == nil {
+		held.kept.Fetched, held.kept.Lines = now, lines
+		held.entries = found
+	} else if !cutOff {
+		held.failures++
+	}
+
+	l.mu.Unlock()
+
+	if cutOff {
+		return
+	}
+
+	if err != nil {
+		const failed = "fetching a list failed"
+
+		// Raised before it is logged, so that the alert is there once the
+		// log line is.
+		raiseFailure(l.params.Alerts, failed, listURL, err)
+		l.params.ProcessLog.Warn(failed, "url", listURL, "error", err.Error())
+
+		return
+	}
+
+	l.params.ProcessLog.Info("fetched a list", "url", listURL, "lines", len(lines))
+}
+
+// raiseFailure raises a source_failure alert into queue, with reason, and
+// in its detail the source that failed, a list's URL, a zone with its key
+// masked or abuseipdb, and err.
+func raiseFailure(queue *alerts.Queue, reason, source string, err error) {
+	queue.Raise(alerts.Alert{
+		Event:  alerts.EventSourceFailure,
+		Reason: reason,
+		Detail: map[string]any{"source": source, "error": err.Error()},
+	})
+}
+
+// get fetches the list at listURL, and returns its lines. An answer other
+// than 200, or a list longer than maxListBytes, is a failure.
+func (l *Lists) get(ctx context.Context, listURL string) ([]string, error) {
+	ctx, cancel := context.WithTimeout(ctx, fetchTimeout)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, listURL, http.NoBody)
+	if err != nil {
+		return nil, fmt.Errorf("make the request: %w", err)
+	}
+
+	res, err := l.httpClient.Do(req)
+	if err != nil {
+		// Do's error names the URL, which the log line and the alert name
+		// already: only what went wrong is kept.
+		return nil, fmt.Errorf("fetch the list: %w", errors.Unwrap(err))
+	}
+
+	defer func() {
+		_ = res.Body.Close()
+	}()
+
+	if res.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("%w %s", errStatus, res.Status)
+	}
+
+	body, err := io.ReadAll(io.LimitReader(res.Body, maxListBytes+1))
+	if err != nil {
+		return nil, fmt.Errorf("read the list: %w", err)
+	}
+
+	if len(body) > maxListBytes {
+		return nil, errTooLong
+	}
+
+	lines := []string{}
+	for line := range strings.Lines(string(body)) {
+		lines = append(lines, strings.TrimSuffix(line, "\n"))
+	}
+
+	return lines, nil
+}
+
+// parse reads the lines of the list at listURL: those of a blocklist, or
+// of the file of AS:percent lines. Anything after a ; or a # on a line is
+// left out, and so is a line left blank. Any other line that does not read
+// is an error naming it by its number.
+func (l *Lists) parse(listURL string, lines []string) (entries, error) {
+	if listURL == l.params.ASNLimitPercentURL {
+		return parsePercents(lines)
+	}
+
+	return parseNetblocks(lines)
+}
+
+// parseNetblocks reads a blocklist's lines, each an address or a netblock
+// as the settings take them.
+func parseNetblocks(lines []string) (entries, error) {
+	found := entries{netblocks: map[netip.Prefix]bool{}}
+
+	for i, line := range lines {
+		text := withoutComment(line)
+		if text == "" {
+			continue
+		}
+
+		netblock, ok := parseNetblock(text)
+		if !ok {
+			return entries{}, fmt.Errorf("line %d %w", i+1, errNotNetblock)
+		}
+
+		found.netblocks[netblock] = true
+
+		if !slices.Contains(found.lengths, netblock.Bits()) {
+			found.lengths = append(found.lengths, netblock.Bits())
+		}
+	}
+
+	return found, nil
+}
+
+// parseNetblock reads text, a line of a blocklist, and reports whether it
+// is an address or a netblock as the settings take them. A client's IPv4
+// address is checked as IPv4, never IPv4-mapped, so an IPv4-mapped line,
+// such as ::ffff:192.0.2.0/120, is read as the IPv4 address or netblock it
+// stands for, 192.0.2.0/24, and a mapped netblock shorter than /96, which
+// stands for none, is refused.
+func parseNetblock(text string) (netip.Prefix, bool) {
+	netblock, err := config.ParseNetblock(text)
+	if err != nil {
+		return netip.Prefix{}, false
+	}
+
+	// The address as written: ParseNetblock's has the bits past the
+	// netblock's length cleared, the ::ffff among them below /96.
+	written, _, _ := strings.Cut(text, "/")
+	if addr, _ := netip.ParseAddr(written); !addr.Is4In6() {
+		return netblock, true
+	}
+
+	if netblock.Bits() < mappedBits {
+		return netip.Prefix{}, false
+	}
+
+	return netip.PrefixFrom(netblock.Addr().Unmap(), netblock.Bits()-mappedBits), true
+}
+
+// parsePercents reads the lines of the file of AS:percent lines, each an
+// AS number, : and a percentage, as SWWAF_ASN_LIMIT_PERCENT takes them. An
+// AS number listed more than once gets the lowest of its percentages.
+func parsePercents(lines []string) (entries, error) {
+	found := entries{percents: map[string]int64{}}
+
+	for i, line := range lines {
+		text := withoutComment(line)
+		if text == "" {
+			continue
+		}
+
+		asnText, percentText, _ := strings.Cut(text, ":")
+		asn, asnErr := config.ParseASN(asnText)
+
+		percent, percentErr := config.ParsePercent(percentText)
+		if asnErr != nil || percentErr != nil {
+			return entries{}, fmt.Errorf("line %d %w", i+1, errNotASNPercent)
+		}
+
+		earlier, listed := found.percents[asn]
+		if !listed || percent < earlier {
+			found.percents[asn] = percent
+		}
+	}
+
+	return found, nil
+}
+
+// withoutComment returns line without anything after a ; or a #, and
+// without the spaces around what is left.
+func withoutComment(line string) string {
+	text, _, _ := strings.Cut(line, ";")
+	text, _, _ = strings.Cut(text, "#")
+
+	return strings.TrimSpace(text)
+}
+
+// contain reports whether the netblocks of a blocklist's copy hold addr:
+// whether addr, cut to one of their lengths, is one of them.
+func (e entries) contain(addr netip.Addr) bool {
+	for _, length := range e.lengths {
+		netblock, err := addr.Prefix(length)
+		if err == nil && e.netblocks[netblock] {
+			return true
+		}
+	}
+
+	return false
+}

internal/reputation/reputation_test.go

@@ -0,0 +1,610 @@
+package reputation_test
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/netip"
+	"net/url"
+	"reflect"
+	"slices"
+	"strings"
+	"sync"
+	"testing"
+	"testing/synctest"
+	"time"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/reputation"
+)
+
+// The tests run in a synctest bubble, where the time package runs on a
+// clock of the test's own: time.Sleep moves it on at once, and
+// synctest.Wait returns once Run waits for the next list to be due, so
+// that every fetch due by then has been made. The stand-in for the
+// servers the lists are fetched from answers without the network, since a
+// fetch waiting on the network would keep that clock from moving on.
+
+const (
+	// dropURL and torURL are the blocklists, and asnURL the file of
+	// AS:percent lines.
+	dropURL = "https://lists.example/drop.txt"
+	torURL  = "https://lists.example/tor.txt"
+	asnURL  = "https://lists.example/asn.txt"
+	// refresh is the tests' SWWAF_BLOCKLIST_REFRESH, and cooldown their
+	// SWWAF_ALERT_COOLDOWN, longer than it.
+	refresh  = 24 * time.Hour
+	cooldown = 48 * time.Hour
+	// drop is a blocklist as the Spamhaus DROP list is written, with an
+	// address and a netblock in each of its comments, which list nothing.
+	drop = "; Spamhaus DROP List 2026/10/07 - (c) 2026 The Spamhaus Project SLL\n" +
+		"; Last-Modified: Wed, 07 Oct 2026 00:00:00 GMT ; 192.0.2.1\n" +
+		"# 198.51.100.0/24\n" +
+		"\n" +
+		"203.0.113.0/24 ; SBL1\n" +
+		"  192.0.2.9  # one address\n" +
+		"2001:db8:1::/48 ; SBL2\n"
+)
+
+func TestListedAddressesAndNetblocksWithTheCommentsLeftOut(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		servers := &standIn{lists: map[string]string{dropURL: drop}}
+		lists := start(t, servers, params(dropURL))
+
+		for addr, want := range map[string][]string{
+			"203.0.113.0":   {dropURL},
+			"203.0.113.255": {dropURL},
+			"192.0.2.9":     {dropURL},
+			"2001:db8:1::7": {dropURL},
+			"203.0.114.0":   nil,
+			"192.0.2.8":     nil,
+			"192.0.2.1":     nil,
+			"198.51.100.7":  nil,
+			"2001:db8:2::7": nil,
+		} {
+			wantListedBy(t, lists, addr, want...)
+		}
+	})
+}
+
+func TestIPv4MappedLineListsTheIPv4AddressOrNetblockItStandsFor(t *testing.T) {
+	t.Parallel()
+
+	now := time.Now()
+	lists := reputation.New(params(dropURL))
+
+	err := lists.Load([]reputation.List{{
+		URL: dropURL, Tried: now, Fetched: now,
+		Lines: []string{"::ffff:192.0.2.9", "::ffff:203.0.113.0/120"},
+	}})
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+
+	for addr, want := range map[string][]string{
+		"192.0.2.9":     {dropURL},
+		"203.0.113.255": {dropURL},
+		"192.0.2.8":     nil,
+		"203.0.114.0":   nil,
+	} {
+		wantListedBy(t, lists, addr, want...)
+	}
+
+	// A mapped netblock shorter than /96 stands for no IPv4 one.
+	err = lists.Load([]reputation.List{{
+		URL: dropURL, Tried: now, Fetched: now, Lines: []string{"::ffff:198.51.100.0/88"},
+	}})
+
+	const want = "the copy of " + dropURL +
+		": line 1 is not an address or a netblock, such as 192.0.2.0/24"
+	if err == nil || err.Error() != want {
+		t.Errorf("error %v, want %s", err, want)
+	}
+}
+
+func TestClientIsListedByEachBlocklistThatListsIt(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		servers := &standIn{lists: map[string]string{
+			dropURL: "203.0.113.0/24\n", torURL: "203.0.113.9\n",
+		}}
+		lists := start(t, servers, params(torURL, dropURL))
+
+		// In the order SWWAF_BLOCKLIST_URLS names them.
+		wantListedBy(t, lists, "203.0.113.9", torURL, dropURL)
+		wantListedBy(t, lists, "203.0.113.8", dropURL)
+	})
+}
+
+func TestListFetchedAgainOnceRefreshHasPassed(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		servers := &standIn{lists: map[string]string{dropURL: "203.0.113.9\n"}}
+		lists := start(t, servers, params(dropURL))
+		began := time.Now()
+
+		wantFetches(t, servers, 1)
+
+		servers.set(dropURL, "203.0.113.10\n")
+		time.Sleep(refresh - time.Nanosecond)
+		wantFetches(t, servers, 1)
+		wantListedBy(t, lists, "203.0.113.9", dropURL)
+
+		time.Sleep(time.Nanosecond)
+		wantFetches(t, servers, 2)
+		wantListedBy(t, lists, "203.0.113.9")
+		wantListedBy(t, lists, "203.0.113.10", dropURL)
+
+		if fetched := lists.Fetched(dropURL); !fetched.Equal(began.Add(refresh)) {
+			t.Errorf("the copy in use was fetched at %s, want %s", fetched,
+				began.Add(refresh))
+		}
+	})
+}
+
+func TestFailedFetchKeepsTheLastGoodCopyAndAlertsOncePerCooldown(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name string
+		// fail has the stand-in answer the fetches after the first so that
+		// they fail with error.
+		fail  func(servers *standIn)
+		error string
+	}{
+		{
+			"an answer other than 200",
+			func(servers *standIn) { servers.set(dropURL, "") },
+			"the server answered 503 Service Unavailable",
+		},
+		{
+			"a line that does not read",
+			func(servers *standIn) { servers.set(dropURL, "203.0.113.10\n<html>\n") },
+			"line 2 is not an address or a netblock, such as 192.0.2.0/24",
+		},
+		{
+			"a list longer than 16 MiB",
+			func(servers *standIn) {
+				servers.set(dropURL, strings.Repeat("#\n", 8<<20+1))
+			},
+			"the list is longer than 16 MiB",
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			synctest.Test(t, func(t *testing.T) {
+				var log bytes.Buffer
+
+				servers := &standIn{lists: map[string]string{dropURL: drop}}
+				queue := newQueue()
+				p := params(dropURL)
+				p.ProcessLog = slog.New(slog.NewJSONHandler(&log, nil))
+				p.Alerts = queue
+				lists := start(t, servers, p)
+				kept := lists.Snapshot()
+
+				tc.fail(servers)
+
+				// Each failure is tried again once refresh has passed since it.
+				for range 2 {
+					time.Sleep(refresh)
+					synctest.Wait()
+				}
+
+				wantFetches(t, servers, 3)
+				wantListedBy(t, lists, "203.0.113.9", dropURL)
+
+				want := kept[0]
+				want.Tried = time.Now()
+
+				if got := lists.Snapshot(); !reflect.DeepEqual(got, []reputation.List{want}) {
+					t.Errorf("lists %+v, want the first copy, last tried now, %+v", got, want)
+				}
+
+				if lists.Failures(dropURL) != 2 {
+					t.Errorf("%d failures, want 2", lists.Failures(dropURL))
+				}
+
+				// One alert for the first failure; the cooldown holds back the
+				// second.
+				wantAlert(t, queue, alerts.Alert{
+					Time:   time.Now().Add(-refresh),
+					Event:  alerts.EventSourceFailure,
+					Reason: "fetching a list failed",
+					Detail: map[string]any{"source": dropURL, "error": tc.error},
+				})
+
+				if !strings.Contains(log.String(), `"msg":"fetching a list failed",`+
+					`"url":"`+dropURL+`","error":"`+tc.error) {
+					t.Errorf("logged\n%s\nwant the failures", log.String())
+				}
+			})
+		})
+	}
+}
+
+func TestFetchNotDoneWithinAMinuteFails(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		servers := &standIn{lists: map[string]string{}, hanging: true}
+		lists := start(t, servers, params(dropURL))
+
+		time.Sleep(time.Minute - time.Nanosecond)
+		synctest.Wait()
+
+		if lists.Failures(dropURL) != 0 {
+			t.Errorf("%d failures before a minute, want none", lists.Failures(dropURL))
+		}
+
+		time.Sleep(time.Nanosecond)
+		synctest.Wait()
+
+		if lists.Failures(dropURL) != 1 {
+			t.Errorf("%d failures after a minute, want 1", lists.Failures(dropURL))
+		}
+	})
+}
+
+func TestKeptCopyIsFetchedAgainOnceRefreshHasPassedSinceItWasFetched(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		servers := &standIn{lists: map[string]string{
+			dropURL: "203.0.113.10\n", torURL: "198.51.100.10\n",
+		}}
+		lists := reputation.New(params(dropURL, torURL))
+		lists.SetTransport(servers)
+
+		// drop.txt was fetched an hour ago, and tor.txt a refresh ago, as
+		// reputation.json says at start.
+		err := lists.Load([]reputation.List{
+			{URL: dropURL, Fetched: time.Now().Add(-time.Hour), Lines: []string{"203.0.113.9"}},
+			{URL: torURL, Fetched: time.Now().Add(-refresh), Lines: []string{"198.51.100.9"}},
+		})
+		if err != nil {
+			t.Fatalf("load: %v", err)
+		}
+
+		run(t, lists)
+
+		wantFetches(t, servers, 1)
+		wantListedBy(t, lists, "203.0.113.9", dropURL)
+		wantListedBy(t, lists, "198.51.100.10", torURL)
+
+		time.Sleep(refresh - time.Hour - time.Nanosecond)
+		wantFetches(t, servers, 1)
+
+		time.Sleep(time.Nanosecond)
+		wantFetches(t, servers, 2)
+		wantListedBy(t, lists, "203.0.113.10", dropURL)
+	})
+}
+
+func TestRestartWaitsRefreshAfterTheLastTryEvenOneThatFailed(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		// drop.txt is fetched, and a refresh later the fetch downloads it
+		// whole but fails on a line that does not read.
+		servers := &standIn{lists: map[string]string{dropURL: "198.51.100.1\n"}}
+		lists := start(t, servers, params(dropURL))
+
+		servers.set(dropURL, "198.51.100.2\n<html>\n")
+		time.Sleep(refresh)
+		wantFetches(t, servers, 2)
+
+		// Restarted with what reputation.json keeps, it waits a refresh
+		// after the failed try, as it does while it runs.
+		restarted := &standIn{lists: map[string]string{dropURL: "198.51.100.2\n"}}
+		again := reputation.New(params(dropURL))
+		again.SetTransport(restarted)
+
+		err := again.Load(lists.Snapshot())
+		if err != nil {
+			t.Fatalf("load: %v", err)
+		}
+
+		run(t, again)
+		wantFetches(t, restarted, 0)
+		wantListedBy(t, again, "198.51.100.1", dropURL)
+
+		time.Sleep(refresh - time.Nanosecond)
+		wantFetches(t, restarted, 0)
+
+		time.Sleep(time.Nanosecond)
+		wantFetches(t, restarted, 1)
+		wantListedBy(t, again, "198.51.100.2", dropURL)
+	})
+}
+
+func TestFetchCutOffAsItStopsIsNoFailureButARestartWaitsForIt(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		// Stopped 30 seconds into the fetch of drop.txt, before tor.txt's.
+		servers := &standIn{lists: map[string]string{}, hanging: true}
+		queue := newQueue()
+		p := params(dropURL, torURL)
+		p.Alerts = queue
+
+		lists := reputation.New(p)
+		lists.SetTransport(servers)
+
+		ctx, stop := context.WithCancel(t.Context())
+		stopped := make(chan struct{})
+
+		go func() {
+			lists.Run(ctx)
+			close(stopped)
+		}()
+
+		time.Sleep(30 * time.Second)
+		stop()
+		<-stopped
+
+		wantFetches(t, servers, 1)
+
+		if lists.Failures(dropURL) != 0 || len(waiting(queue)) != 0 {
+			t.Errorf("%d failures and alerts %+v, want none", lists.Failures(dropURL),
+				waiting(queue))
+		}
+
+		// Restarted an hour later with what reputation.json keeps, it fetches
+		// tor.txt, never tried, at once, and drop.txt a refresh after its
+		// cut-off try.
+		time.Sleep(time.Hour)
+
+		restarted := &standIn{lists: map[string]string{
+			dropURL: "203.0.113.7\n", torURL: "198.51.100.7\n",
+		}}
+		again := reputation.New(params(dropURL, torURL))
+		again.SetTransport(restarted)
+
+		err := again.Load(lists.Snapshot())
+		if err != nil {
+			t.Fatalf("load: %v", err)
+		}
+
+		run(t, again)
+		wantFetches(t, restarted, 1)
+		wantListedBy(t, again, "198.51.100.7", torURL)
+
+		time.Sleep(refresh - time.Hour - time.Nanosecond)
+		wantFetches(t, restarted, 1)
+
+		time.Sleep(time.Nanosecond)
+		wantFetches(t, restarted, 2)
+		wantListedBy(t, again, "203.0.113.7", dropURL)
+	})
+}
+
+func TestASNLimitPercentFileGivesEachASNumberItsLowestPercentage(t *testing.T) {
+	t.Parallel()
+
+	synctest.Test(t, func(t *testing.T) {
+		servers := &standIn{lists: map[string]string{
+			asnURL: "# hosting networks\nAS14061:50 ; DigitalOcean\nas16276:25\n\n" +
+				"AS14061:10\nAS14061:30\n",
+		}}
+		p := params()
+		p.ASNLimitPercentURL = asnURL
+		lists := start(t, servers, p)
+
+		for asn, want := range map[string]int64{"AS14061": 10, "AS16276": 25} {
+			percent, listed := lists.ASNLimitPercent(asn)
+			if !listed || percent != want {
+				t.Errorf("%s has %d (listed %t), want %d", asn, percent, listed, want)
+			}
+		}
+
+		if _, listed := lists.ASNLimitPercent("AS64496"); listed {
+			t.Error("AS64496 is listed")
+		}
+
+		// A line that does not read fails the fetch.
+		servers.set(asnURL, "AS14061:50\nAS16276\n")
+		time.Sleep(refresh)
+		synctest.Wait()
+
+		if lists.Failures(asnURL) != 1 {
+			t.Errorf("%d failures, want 1", lists.Failures(asnURL))
+		}
+	})
+}
+
+func TestLoadDropsCopiesOfListsNotNamedAndRefusesOnesThatDoNotRead(t *testing.T) {
+	t.Parallel()
+
+	fetched := time.Date(2026, 10, 6, 0, 0, 0, 0, time.UTC)
+	kept := reputation.List{
+		URL: dropURL, Tried: fetched, Fetched: fetched, Lines: []string{"203.0.113.9"},
+	}
+	lists := reputation.New(params(dropURL))
+
+	err := lists.Load([]reputation.List{kept, {
+		URL: torURL, Tried: fetched, Fetched: fetched, Lines: []string{"198.51.100.9"},
+	}})
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+
+	if got := lists.Snapshot(); !reflect.DeepEqual(got, []reputation.List{kept}) {
+		t.Errorf("copies %+v, want only %+v", got, kept)
+	}
+
+	err = lists.Load([]reputation.List{{URL: dropURL, Fetched: fetched, Lines: []string{
+		"; DROP", "203.0.113.300",
+	}}})
+
+	const want = "the copy of " + dropURL +
+		": line 2 is not an address or a netblock, such as 192.0.2.0/24"
+	if err == nil || err.Error() != want {
+		t.Errorf("error %v, want %s", err, want)
+	}
+
+	if got := lists.Snapshot(); !reflect.DeepEqual(got, []reputation.List{kept}) {
+		t.Errorf("copies %+v after the error, want %+v still", got, kept)
+	}
+}
+
+// standIn is a stand-in for the servers the lists are fetched from. It
+// notes the URL of each fetch.
+type standIn struct {
+	mu sync.Mutex
+	// lists are what it answers with, by URL; it answers a URL it has no
+	// list for with 503, and none at all while hanging.
+	lists   map[string]string
+	hanging bool
+	fetches []string
+}
+
+// RoundTrip has the stand-in answer req, in place of the network. A fetch
+// abandoned before the stand-in answers fails, as over the network.
+func (s *standIn) RoundTrip(req *http.Request) (*http.Response, error) {
+	s.mu.Lock()
+	s.fetches = append(s.fetches, req.URL.String())
+	list, found := s.lists[req.URL.String()]
+	hanging := s.hanging
+	s.mu.Unlock()
+
+	if hanging {
+		<-req.Context().Done()
+
+		return nil, req.Context().Err()
+	}
+
+	status := http.StatusOK
+	if !found {
+		status = http.StatusServiceUnavailable
+	}
+
+	return &http.Response{
+		StatusCode: status,
+		Status:     fmt.Sprintf("%d %s", status, http.StatusText(status)),
+		Header:     http.Header{},
+		Body:       io.NopCloser(strings.NewReader(list)),
+		Request:    req,
+	}, nil
+}
+
+// set has the stand-in answer listURL with list, or with 503 for "".
+func (s *standIn) set(listURL, list string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if list == "" {
+		delete(s.lists, listURL)
+
+		return
+	}
+
+	s.lists[listURL] = list
+}
+
+// params returns the Params of the blocklists at urls, refreshed every
+// refresh, by the bubble's clock, with alerts to a queue that sends none.
+func params(urls ...string) reputation.Params {
+	return reputation.Params{
+		BlocklistURLs: urls,
+		Refresh:       refresh,
+		Now:           time.Now,
+		ProcessLog:    slog.New(slog.DiscardHandler),
+		Alerts:        newQueue(),
+	}
+}
+
+// newQueue returns a queue of alerts to a webhook that is never sent
+// them, with a cooldown of cooldown.
+func newQueue() *alerts.Queue {
+	return alerts.New(alerts.Params{
+		WebhookURL: &url.URL{Scheme: "https", Host: "alerts.example"},
+		Events:     alerts.Events(),
+		Cooldown:   cooldown,
+		Now:        time.Now,
+	})
+}
+
+// start returns the lists of p, fetched through servers by Run, which runs
+// until the test ends, once Run has fetched those due at start.
+func start(t *testing.T, servers *standIn, p reputation.Params) *reputation.Lists {
+	t.Helper()
+
+	lists := reputation.New(p)
+	lists.SetTransport(servers)
+	run(t, lists)
+
+	return lists
+}
+
+// run runs lists' Run until the test ends, and waits until it has fetched
+// the lists due.
+func run(t *testing.T, lists *reputation.Lists) {
+	t.Helper()
+
+	ctx, stop := context.WithCancel(t.Context())
+	stopped := make(chan struct{})
+
+	go func() {
+		lists.Run(ctx)
+		close(stopped)
+	}()
+
+	t.Cleanup(func() {
+		stop()
+		<-stopped
+	})
+
+	synctest.Wait()
+}
+
+// wantFetches waits until Run has made the fetches due, and checks how
+// many the servers have had.
+func wantFetches(t *testing.T, servers *standIn, want int) {
+	t.Helper()
+
+	synctest.Wait()
+
+	servers.mu.Lock()
+	got := len(servers.fetches)
+	servers.mu.Unlock()
+
+	if got != want {
+		t.Errorf("%d fetches, want %d", got, want)
+	}
+}
+
+// wantListedBy checks the URLs of the blocklists lists says list addr.
+func wantListedBy(t *testing.T, lists *reputation.Lists, addr string, want ...string) {
+	t.Helper()
+
+	got := lists.ListedBy(netip.MustParseAddr(addr))
+	if !slices.Equal(got, want) {
+		t.Errorf("%s is listed by %v, want %v", addr, got, want)
+	}
+}
+
+// waiting returns the alerts waiting in queue.
+func waiting(queue *alerts.Queue) []alerts.Alert {
+	return queue.Snapshot().Waiting[alerts.DestinationWebhook]
+}
+
+// wantAlert checks that want is the one alert waiting in queue, and that
+// the cooldown has held back one repeat of it.
+func wantAlert(t *testing.T, queue *alerts.Queue, want alerts.Alert) {
+	t.Helper()
+
+	got := waiting(queue)
+	if len(got) != 1 || !reflect.DeepEqual(got[0], want) || queue.Suppressed() != 1 {
+		t.Errorf("alerts waiting %+v, %d held back, want only %+v and 1", got,
+			queue.Suppressed(), want)
+	}
+}

internal/requestlog/requestlog.go

@@ -35,7 +35,9 @@ const (
 	// rule.
 	ActionRuleBlocked = "rule_blocked"
 	// ActionDenied is a request refused because its client is in
-	// SWWAF_DENY_NETS.
+	// SWWAF_DENY_NETS, in a blocklist while SWWAF_BLOCKLIST_ACTION is deny,
+	// or listed by a DNSBL zone, or scored a hit by AbuseIPDB, while
+	// SWWAF_REPUTATION_ACTION is deny.
 	ActionDenied = "denied"
 	// ActionCountryDenied is a request refused for its client's country.
 	ActionCountryDenied = "country_denied"
@@ -45,7 +47,7 @@ const (
 )
 
 // OffenceLimit is the offence a request line names for a request that
-// broke a rate limit.
+// broke a rate limit, or whose bytes broke a byte limit.
 const OffenceLimit = "limit"
 
 // timeLayout is RFC 3339 with milliseconds.
@@ -117,14 +119,30 @@ type Line struct {
 	// ActionBanned, ActionCountryDenied, ActionRateLimited or
 	// ActionRuleBlocked.
 	WouldAction string `json:"would_action,omitempty"`
-	// Counts are the client's requests as the rate limits counted them
-	// with this one, for a request they counted.
+	// LimitPercent and LimitPercentSetting are, for a request the rate
+	// limits counted whose client a biased threshold gives a percentage of
+	// the rate limits below 100, that percentage and the setting that gave
+	// it. BytesPercent and BytesPercentSetting are the same for the byte
+	// limits.
+	LimitPercent        *int64 `json:"limit_percent,omitempty"`
+	LimitPercentSetting string `json:"limit_percent_setting,omitempty"`
+	BytesPercent        *int64 `json:"bytes_percent,omitempty"`
+	BytesPercentSetting string `json:"bytes_percent_setting,omitempty"`
+	// Counts are, for a request the rate limits counted, the client's
+	// requests as they counted them with this one, and its bytes as the
+	// byte limits counted them, with this request's once it has ended if
+	// they count them.
 	Counts ratelimit.Counts `json:"counts,omitzero"`
 	// RuleIDs are the ids of the rule file rules the request matched.
 	RuleIDs []string `json:"rule_ids,omitempty"`
-	// LimitHit is the window whose rate limit the request went over:
-	// minute, hour or day.
+	// LimitHit is the window whose limit the request went over, named as
+	// Counts names its count: minute, hour or day for a rate limit, and
+	// minute_bytes, hour_bytes or day_bytes for a byte limit.
 	LimitHit string `json:"limit_hit,omitempty"`
+	// Reputation are the URLs of the blocklists that list the client, then
+	// the DNSBL zones whose verdict lists it, their keys masked, then
+	// abuseipdb when its score is a hit.
+	Reputation []string `json:"reputation,omitempty"`
 	// Offence is the offence the request was held as, OffenceLimit.
 	Offence string `json:"offence,omitempty"`
 	// BanExpires is when the ban the request made, or was refused under,

internal/smallwebwaf/smallwebwaf.go

@@ -21,6 +21,7 @@ import (
 	"sneak.berlin/go/smallwebwaf/internal/lookup"
 	"sneak.berlin/go/smallwebwaf/internal/proxy"
 	"sneak.berlin/go/smallwebwaf/internal/remotelog"
+	"sneak.berlin/go/smallwebwaf/internal/reputation"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
 	"sneak.berlin/go/smallwebwaf/internal/rules"
 	"sneak.berlin/go/smallwebwaf/internal/state"
@@ -169,14 +170,15 @@ func newServer(
 	}
 
 	server := proxy.New(proxy.Params{
-		Config:     cfg,
-		RequestLog: stdout,
-		ProcessLog: processLog,
-		GeoJSURL:   lookup.URL,
-		LookupFile: lookupFile,
-		Now:        now,
-		Rules:      ruleFiles,
-		Alerts:     alertQueue,
+		Config:       cfg,
+		RequestLog:   stdout,
+		ProcessLog:   processLog,
+		GeoJSURL:     lookup.URL,
+		AbuseIPDBURL: reputation.AbuseIPDBURL,
+		LookupFile:   lookupFile,
+		Now:          now,
+		Rules:        ruleFiles,
+		Alerts:       alertQueue,
 	})
 	server.Metrics.AddAlerts(alertQueue)
 
@@ -200,7 +202,11 @@ func loadStateFiles(
 		Ledger:          server.Ledger,
 		Limiter:         server.Limiter,
 		GeoJS:           server.GeoJS,
+		Lists:           server.Lists,
+		DNSBL:           server.DNSBL,
+		AbuseIPDB:       server.AbuseIPDB,
 		Alerts:          alertQueue,
+		Anomalies:       server.Anomalies,
 		Now:             now,
 		ProcessLog:      processLog,
 		Metrics:         server.Metrics,
@@ -266,8 +272,9 @@ func startSending(
 
 // serve serves requests on listener, writes the state files as they are
 // due, takes in an admin's edits of them, reads the rule files again as
-// they change, and the lookup database when it is replaced, and sends the
-// alerts, until ctx is done. Then it gives the requests in progress
+// they change, and the lookup database when it is replaced, fetches the
+// lists the settings name by URL as they are due, and sends the alerts,
+// until ctx is done. Then it gives the requests in progress
 // shutdownTimeout to finish, and writes every state file, alerts.json with
 // the alerts still waiting.
 func serve(
@@ -292,6 +299,7 @@ func serve(
 			server.LookupFile.Watch(writing)
 		}
 	})
+	listsFetched := inBackground(func() { server.Lists.Run(writing) })
 	alertsSent := inBackground(func() { alertQueue.Run(writing) })
 
 	select {
@@ -335,6 +343,7 @@ func serve(
 	<-watched
 	<-rulesWatched
 	<-lookupFileWatched
+	<-listsFetched
 	<-alertsSent
 
 	err = files.WriteAll()

internal/smallwebwaf/smallwebwaf_test.go

@@ -38,6 +38,7 @@ const (
 	stateWriteDelay      = "SWWAF_STATE_WRITE_DELAY"
 	stateCounterInterval = "SWWAF_STATE_COUNTER_INTERVAL"
 	rateLimitPerDay      = "SWWAF_RATE_LIMIT_PER_DAY"
+	rateLimitExemptNets  = "SWWAF_RATE_LIMIT_EXEMPT_NETS"
 	rulesDir             = "SWWAF_RULES_DIR"
 	lookupSource         = "SWWAF_LOOKUP_SOURCE"
 	lookupDBPath         = "SWWAF_LOOKUP_DB_PATH"
@@ -522,7 +523,7 @@ func TestLookupDatabaseReplacedWhileRunningTakesEffect(t *testing.T) {
 		// The requests sent until a replacement takes effect, and those
 		// for the metrics, must not break a rate limit, whose ban would
 		// refuse them too.
-		"SWWAF_RATE_LIMIT_EXEMPT_NETS": placed + "," + localhost,
+		rateLimitExemptNets: placed + "," + localhost,
 	}
 	began := time.Now()
 	// Each replacement is written beside the file and renamed over it, as
@@ -573,6 +574,111 @@ func TestLookupDatabaseReplacedWhileRunningTakesEffect(t *testing.T) {
 	}
 }
 
+func TestBlocklistTriesAndCopiesKeptInReputationJSONAcrossRestarts(t *testing.T) {
+	t.Parallel()
+
+	const (
+		token    = "0123456789abcdef0123456789abcdef"
+		torPath  = "/tor.txt"
+		dropPath = "/drop.txt"
+		// copyright is the DROP list's date and copyright line.
+		copyright = "; Spamhaus DROP List 2026/10/07 - (c) 2026 The Spamhaus Project SLL"
+	)
+
+	failing, torFetches := new(atomic.Bool), new(atomic.Int32)
+	lists := map[string]string{
+		torPath:  "198.51.100.0/24\n",
+		dropPath: copyright + "\n" + placed + " ; SBL1\n",
+	}
+	server := httptest.NewServer(http.HandlerFunc(
+		func(w http.ResponseWriter, r *http.Request) {
+			if r.URL.Path == torPath {
+				torFetches.Add(1)
+			}
+
+			if failing.Load() {
+				w.WriteHeader(http.StatusServiceUnavailable)
+
+				return
+			}
+
+			_, _ = io.WriteString(w, lists[r.URL.Path])
+		}))
+	t.Cleanup(server.Close)
+
+	torURL, dropURL := server.URL+torPath, server.URL+dropPath
+	dir := t.TempDir()
+	env := map[string]string{
+		listenAddr:             localhost + ":0",
+		upstreamURL:            startApp(t),
+		stateDir:               dir,
+		rulesDir:               t.TempDir(),
+		trustedProxies:         localhost + "/32",
+		metricsToken:           token,
+		instanceName:           instance,
+		"SWWAF_BLOCKLIST_URLS": torURL,
+		// The requests sent until the list takes effect, and those for the
+		// metrics, must not break a rate limit, whose ban would refuse them
+		// too.
+		rateLimitExemptNets: placed + "," + localhost,
+	}
+	failures := `smallwebwaf_reputation_failures_total{instance="fsn1app1/gitea",` +
+		`source="` + torURL + `"} `
+
+	// tor.txt cannot be fetched at first, which is counted.
+	failing.Store(true)
+	runUntilStopped(t, env, func(url string) {
+		metricsWith(t, url+"_smallwebwaf/metrics", token, failures+"1")
+	})
+
+	// Restarted with drop.txt named after it and the server answering, tor.txt
+	// waits SWWAF_BLOCKLIST_REFRESH after its failed try, kept in reputation.json,
+	// while drop.txt, never tried, is fetched at once. Lists are fetched in the
+	// order named, so once drop.txt refuses the client, tor.txt has had its turn.
+	failing.Store(false)
+
+	env["SWWAF_BLOCKLIST_URLS"] = torURL + "," + dropURL
+	out := runUntilStopped(t, env, func(url string) {
+		for statusFrom(t, url, placed) != http.StatusForbidden {
+			time.Sleep(pollInterval)
+		}
+	})
+	wantDeniedByList(t, out.line(t, "action", "denied"), dropURL)
+
+	if fetches := torFetches.Load(); fetches != 1 {
+		t.Errorf("tor.txt fetched %d times, want once, before the restart", fetches)
+	}
+
+	// After another restart, with the server failing, the copy of drop.txt
+	// kept in reputation.json, its copyright line included, refuses the
+	// client from the first request.
+	failing.Store(true)
+
+	out = runUntilStopped(t, env, func(url string) {
+		wantStatus(t, url, placed, http.StatusForbidden)
+	})
+	wantDeniedByList(t, out.line(t, "type", "request"), dropURL)
+
+	path := filepath.Join(dir, "reputation.json")
+
+	kept, err := os.ReadFile(path) //nolint:gosec // a file in the test's directory
+	if err != nil || !strings.Contains(string(kept), `"`+copyright+`"`) {
+		t.Errorf("reputation.json holds\n%s\nwant the copy with %q (%v)", kept, copyright,
+			err)
+	}
+}
+
+// wantDeniedByList checks that the request log line is of a request the
+// blocklist at listURL refused.
+func wantDeniedByList(t *testing.T, line map[string]any, listURL string) {
+	t.Helper()
+
+	reputation, _ := line["reputation"].([]any)
+	if line["action"] != "denied" || len(reputation) != 1 || reputation[0] != listURL {
+		t.Errorf("request log line %v, want one denied for %s", line, listURL)
+	}
+}
+
 func TestLookupDatabaseThatCannotBeReadStopsTheStart(t *testing.T) {
 	t.Parallel()
 
@@ -1014,7 +1120,7 @@ func wantStartingLine(t *testing.T, line map[string]any, appURL, dir string) {
 		"SWWAF_REQUEST_MAX_BYTES":               "100M",
 		"SWWAF_RESPONSE_MAX_BYTES":              "5G",
 		"SWWAF_ALLOW_NETS":                      "",
-		"SWWAF_RATE_LIMIT_EXEMPT_NETS":          "",
+		rateLimitExemptNets:                     "",
 		"SWWAF_DENY_NETS":                       "",
 		"SWWAF_RATE_LIMIT_PER_MINUTE":           "1000",
 		"SWWAF_RATE_LIMIT_PER_HOUR":             "10000",

internal/state/state.go

@@ -1,8 +1,11 @@
 // Package state keeps smallwebwaf's state in JSON files in
 // SWWAF_STATE_DIR, as the "Persistent state" section of SPEC.md describes:
 // bans.json holds the bans, clients.json each client's counters and
-// history, lookups.json GeoJS's answers, and alerts.json the cooldowns,
-// the hour under way and the alerts waiting for each destination. Load
+// history, lookups.json GeoJS's answers, reputation.json the last try and
+// last good copy of each list fetched from a URL, the DNSBL zones'
+// verdicts, and AbuseIPDB's scores and checks spent, and alerts.json the
+// cooldowns, the hour under way, the alerts waiting for each destination
+// and the anomaly counters. Load
 // reads them at start, Watch takes in an admin's edit of one while
 // smallwebwaf runs, and Run and WriteAll write them. The disk is read and
 // written outside the parts' locks, which are held only to take a
@@ -29,10 +32,12 @@ import (
 
 	"github.com/fsnotify/fsnotify"
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/anomaly"
 	"sneak.berlin/go/smallwebwaf/internal/bans"
 	"sneak.berlin/go/smallwebwaf/internal/lookup"
 	"sneak.berlin/go/smallwebwaf/internal/metrics"
 	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
+	"sneak.berlin/go/smallwebwaf/internal/reputation"
 )
 
 // version is the version of the files' format, the only one read.
@@ -44,10 +49,11 @@ const fileMode = 0o600
 
 // The state files' names.
 const (
-	bansJSON    = "bans.json"
-	clientsJSON = "clients.json"
-	lookupsJSON = "lookups.json"
-	alertsJSON  = "alerts.json"
+	bansJSON       = "bans.json"
+	clientsJSON    = "clients.json"
+	lookupsJSON    = "lookups.json"
+	reputationJSON = "reputation.json"
+	alertsJSON     = "alerts.json"
 )
 
 var (
@@ -56,6 +62,7 @@ var (
 	errMissing     = errors.New("has no")
 	errCause       = errors.New("is not limit, attack or admin")
 	errDestination = errors.New("is not webhook, slack or ntfy")
+	errScope       = errors.New("is not client, net, asn, total or watch")
 	errWaitingList = errors.New(`waiting is a list, but now lists the alerts by ` +
 		`destination: put the list under "webhook", as "waiting": {"webhook": [...]}, ` +
 		`or remove the file`)
@@ -70,13 +77,17 @@ type Params struct {
 	// is (SWWAF_STATE_COUNTER_INTERVAL).
 	WriteDelay      time.Duration
 	CounterInterval time.Duration
-	// Ledger, Limiter, GeoJS and Alerts hold the state. Alerts also
-	// receive a file_error alert for an edit set aside, and for a write
-	// that fails while smallwebwaf runs.
-	Ledger  *bans.Ledger
-	Limiter *ratelimit.Limiter
-	GeoJS   *lookup.GeoJS
-	Alerts  *alerts.Queue
+	// Ledger, Limiter, GeoJS, Lists, DNSBL, AbuseIPDB, Alerts and Anomalies
+	// hold the state. Alerts also receive a file_error alert for an edit set
+	// aside, and for a write that fails while smallwebwaf runs.
+	Ledger    *bans.Ledger
+	Limiter   *ratelimit.Limiter
+	GeoJS     *lookup.GeoJS
+	Lists     *reputation.Lists
+	DNSBL     *reputation.DNSBL
+	AbuseIPDB *reputation.AbuseIPDB
+	Alerts    *alerts.Queue
+	Anomalies *anomaly.Counters
 	// Now tells the time by which the counters' buckets run out, normally
 	// time.Now in UTC.
 	Now func() time.Time
@@ -134,12 +145,24 @@ type lookupsFile struct {
 	Lookups []lookup.Answer `json:"lookups"`
 }
 
+// reputationFile is reputation.json, indented for an admin to read and
+// edit, so that each line of a list's copy is on a line of its own.
+type reputationFile struct {
+	Version   int                  `json:"version"`
+	Lists     []reputation.List    `json:"lists"`
+	Verdicts  []reputation.Verdict `json:"verdicts"`
+	AbuseIPDB reputation.Checks    `json:"abuseipdb"`
+}
+
 // alertsFile is alerts.json, indented for an admin to read and edit.
+//
+//nolint:tagliatelle // the state files use snake_case, as the request log does
 type alertsFile struct {
-	Version   int                       `json:"version"`
-	Cooldowns []alerts.Cooldown         `json:"cooldowns"`
-	Hour      alerts.Hour               `json:"hour"`
-	Waiting   map[string][]alerts.Alert `json:"waiting"`
+	Version         int                       `json:"version"`
+	Cooldowns       []alerts.Cooldown         `json:"cooldowns"`
+	Hour            alerts.Hour               `json:"hour"`
+	Waiting         map[string][]alerts.Alert `json:"waiting"`
+	AnomalyCounters []anomaly.Counter         `json:"anomaly_counters"`
 }
 
 // stateFile is the struct of a state file. Once the file is decoded, its
@@ -152,10 +175,10 @@ type stateFile interface {
 }
 
 // Load checks that files can be written in Dir, and reads the state files
-// in it into the ledger, the limiter and GeoJS. A missing file is empty
-// state, as on a first start. A file that does not parse, has an unknown
-// version, or has an entry without a field it needs, is an error that
-// names the file and, where the JSON decoder tells it, the line and
+// in it into the parts of Params that hold the state. A missing file is
+// empty state, as on a first start. A file that does not parse, has an
+// unknown version, or has an entry without a field it needs, is an error
+// that names the file and, where the JSON decoder tells it, the line and
 // column, or else the entry.
 func Load(params Params) (*Files, error) {
 	err := checkWritable(params.Dir)
@@ -168,16 +191,17 @@ func Load(params Params) (*Files, error) {
 	bansRead, bansErr := f.read(bansJSON)
 	clientsRead, clientsErr := f.read(clientsJSON)
 	lookupsRead, lookupsErr := f.read(lookupsJSON)
+	reputationRead, reputationErr := f.read(reputationJSON)
 	alertsRead, alertsErr := f.read(alertsJSON)
 
-	err = errors.Join(bansErr, clientsErr, lookupsErr, alertsErr)
+	err = errors.Join(bansErr, clientsErr, lookupsErr, reputationErr, alertsErr)
 	if err != nil {
 		return nil, err
 	}
 
 	params.ProcessLog.Info("read the state files", "directory", params.Dir,
 		"bans", bansRead, "clients", clientsRead, "lookups", lookupsRead,
-		"alerts_waiting", alertsRead)
+		"lists", reputationRead, "alerts_waiting", alertsRead)
 
 	return f, nil
 }
@@ -206,7 +230,9 @@ func (f *Files) Run(ctx context.Context) {
 
 			f.logFailure(bansJSON, f.writeFile(bansJSON))
 		case <-interval.C:
-			for _, name := range []string{bansJSON, clientsJSON, lookupsJSON, alertsJSON} {
+			for _, name := range []string{
+				bansJSON, clientsJSON, lookupsJSON, reputationJSON, alertsJSON,
+			} {
 				f.logFailure(name, f.writeFile(name))
 			}
 		}
@@ -217,7 +243,7 @@ func (f *Files) Run(ctx context.Context) {
 // fails does not keep the others from being written.
 func (f *Files) WriteAll() error {
 	return errors.Join(f.writeFile(bansJSON), f.writeFile(clientsJSON),
-		f.writeFile(lookupsJSON), f.writeFile(alertsJSON))
+		f.writeFile(lookupsJSON), f.writeFile(reputationJSON), f.writeFile(alertsJSON))
 }
 
 // Watch watches Dir until ctx is done, and takes in an admin's edit of a
@@ -252,7 +278,7 @@ func (f *Files) Watch(ctx context.Context) {
 			return
 		case event := <-watcher.Events:
 			switch name := filepath.Base(event.Name); name {
-			case bansJSON, clientsJSON, lookupsJSON, alertsJSON:
+			case bansJSON, clientsJSON, lookupsJSON, reputationJSON, alertsJSON:
 				f.fileChanged(name)
 			}
 		case err = <-watcher.Errors:
@@ -398,32 +424,29 @@ func (f *Files) takeIn(name string, data []byte, edit bool) (int, error) {
 
 		f.params.GeoJS.Load(file.Lookups)
 		entries = len(file.Lookups)
-	case alertsJSON:
-		// waiting was a list, of the alerts waiting for the webhook, before
-		// alerts went to Slack and ntfy too.
-		var written struct {
-			Waiting json.RawMessage `json:"waiting"`
-		}
-
-		if json.Unmarshal(data, &written) == nil &&
-			bytes.HasPrefix(written.Waiting, []byte("[")) {
-			return 0, fmt.Errorf("%s: %w", path, errWaitingList)
-		}
-
-		var file alertsFile
+	case reputationJSON:
+		var file reputationFile
 
 		err := parse(path, data, &file)
 		if err != nil {
 			return 0, err
 		}
 
-		f.params.Alerts.Load(alerts.State{
-			Cooldowns: file.Cooldowns, Hour: file.Hour, Waiting: file.Waiting,
-		})
-
-		for _, waiting := range file.Waiting {
-			entries += len(waiting)
+		err = f.params.Lists.Load(file.Lists)
+		if err != nil {
+			return 0, fmt.Errorf("%s: %w", path, err)
 		}
+
+		f.params.DNSBL.Load(file.Verdicts)
+		f.params.AbuseIPDB.Load(file.AbuseIPDB)
+		entries = len(file.Lists)
+	case alertsJSON:
+		waiting, err := f.takeInAlerts(path, data)
+		if err != nil {
+			return 0, err
+		}
+
+		entries = waiting
 	}
 
 	f.sums[name] = sha256.Sum256(data)
@@ -431,6 +454,41 @@ func (f *Files) takeIn(name string, data []byte, edit bool) (int, error) {
 	return entries, nil
 }
 
+// takeInAlerts parses data, what alerts.json, at path, holds, puts it
+// into the alerts and the anomaly counters, in place of what they held,
+// and returns how many alerts wait in it, as takeIn describes.
+func (f *Files) takeInAlerts(path string, data []byte) (int, error) {
+	// waiting was a list, of the alerts waiting for the webhook, before
+	// alerts went to Slack and ntfy too.
+	var written struct {
+		Waiting json.RawMessage `json:"waiting"`
+	}
+
+	if json.Unmarshal(data, &written) == nil &&
+		bytes.HasPrefix(written.Waiting, []byte("[")) {
+		return 0, fmt.Errorf("%s: %w", path, errWaitingList)
+	}
+
+	var file alertsFile
+
+	err := parse(path, data, &file)
+	if err != nil {
+		return 0, err
+	}
+
+	f.params.Alerts.Load(alerts.State{
+		Cooldowns: file.Cooldowns, Hour: file.Hour, Waiting: file.Waiting,
+	})
+	f.params.Anomalies.Load(file.AnomalyCounters, f.params.Now())
+
+	entries := 0
+	for _, waiting := range file.Waiting {
+		entries += len(waiting)
+	}
+
+	return entries, nil
+}
+
 // writeFile writes the state file name from what smallwebwaf holds. An
 // edit made since smallwebwaf last read or wrote the file is taken in
 // first, so that it is not overwritten, or set aside if it does not
@@ -506,34 +564,39 @@ func (f *Files) setAside(name string, parseErr error) error {
 func (f *Files) encode(name string) ([]byte, error) {
 	switch name {
 	case bansJSON:
-		file := bansFile{Version: version, Bans: BanEntries(f.params.Ledger.Snapshot())}
-
-		data, err := json.MarshalIndent(file, "", "    ")
-		if err != nil {
-			return nil, err
-		}
-
-		return append(data, '\n'), nil
+		return encodeIndented(bansFile{
+			Version: version, Bans: BanEntries(f.params.Ledger.Snapshot()),
+		})
 	case clientsJSON:
 		return encodeOnePerLine("clients", f.params.Limiter.Snapshot())
 	case lookupsJSON:
 		return encodeOnePerLine("lookups", f.params.GeoJS.Snapshot())
+	case reputationJSON:
+		return encodeIndented(reputationFile{
+			Version: version, Lists: f.params.Lists.Snapshot(),
+			Verdicts: f.params.DNSBL.Snapshot(), AbuseIPDB: f.params.AbuseIPDB.Snapshot(),
+		})
 	default: // alerts.json
 		held := f.params.Alerts.Snapshot()
-		file := alertsFile{
+
+		return encodeIndented(alertsFile{
 			Version: version, Cooldowns: held.Cooldowns, Hour: held.Hour,
-			Waiting: held.Waiting,
-		}
-
-		data, err := json.MarshalIndent(file, "", "    ")
-		if err != nil {
-			return nil, err
-		}
-
-		return append(data, '\n'), nil
+			Waiting: held.Waiting, AnomalyCounters: f.params.Anomalies.Snapshot(),
+		})
 	}
 }
 
+// encodeIndented encodes file, a state file's struct, indented for an
+// admin to read and edit.
+func encodeIndented(file any) ([]byte, error) {
+	data, err := json.MarshalIndent(file, "", "    ")
+	if err != nil {
+		return nil, err
+	}
+
+	return append(data, '\n'), nil
+}
+
 // BanEntries returns held as bans.json lists them, an empty list for
 // none.
 func BanEntries(held []bans.Ban) []BanEntry {
@@ -615,8 +678,8 @@ func (f *bansFile) check(data []byte) error {
 }
 
 // check refuses a client without its address, which would count nobody's
-// requests, or with requests in a window but no start, which would drop
-// them and give the client a fresh allowance.
+// requests, or with requests or bytes in a window but no start, which
+// would drop them and give the client a fresh allowance.
 func (f *clientsFile) check([]byte) error {
 	for i, client := range f.Clients {
 		switch {
@@ -628,6 +691,12 @@ func (f *clientsFile) check([]byte) error {
 			return missing(i, "hour.start")
 		case countsWithoutStart(client.Day):
 			return missing(i, "day.start")
+		case countsWithoutStart(client.MinuteBytes):
+			return missing(i, "minute_bytes.start")
+		case countsWithoutStart(client.HourBytes):
+			return missing(i, "hour_bytes.start")
+		case countsWithoutStart(client.DayBytes):
+			return missing(i, "day_bytes.start")
 		}
 	}
 
@@ -665,10 +734,92 @@ func (f *lookupsFile) check(data []byte) error {
 	return nil
 }
 
+// check refuses a list without its URL, which would name no list, or the
+// time it was last tried, which would have it fetched at once, and a copy
+// of it without the time it was fetched, or without its lines, which hold
+// the list. It refuses a verdict without its zone or its client, which
+// would be about no one, whether the zone lists the client, or the time
+// it was fetched, which would drop it, and so an AbuseIPDB score without
+// its client, the score, or the time it was fetched. A verdict's listed is
+// false for a client the zone does not list, and a score can be 0, which
+// the structs cannot tell from a missing one, so each is read again as
+// written.
+func (f *reputationFile) check(data []byte) error {
+	for i, kept := range f.Lists {
+		switch {
+		case kept.URL == "":
+			return missing(i, "url")
+		case kept.Tried.IsZero():
+			return missing(i, "tried")
+		case kept.Fetched.IsZero() && kept.Lines != nil:
+			return missing(i, "fetched")
+		case kept.Lines == nil && !kept.Fetched.IsZero():
+			return missing(i, "lines")
+		}
+	}
+
+	var written struct {
+		Verdicts []struct {
+			Listed *bool `json:"listed"`
+		} `json:"verdicts"`
+	}
+
+	err := json.Unmarshal(data, &written)
+	if err != nil {
+		return err
+	}
+
+	for i, verdict := range f.Verdicts {
+		switch {
+		case verdict.Zone == "":
+			return fmt.Errorf("verdicts %w", missing(i, "zone"))
+		case !verdict.Client.IsValid():
+			return fmt.Errorf("verdicts %w", missing(i, "client"))
+		case written.Verdicts[i].Listed == nil:
+			return fmt.Errorf("verdicts %w", missing(i, "listed"))
+		case verdict.Fetched.IsZero():
+			return fmt.Errorf("verdicts %w", missing(i, "fetched"))
+		}
+	}
+
+	return checkScores(f.AbuseIPDB.Scores, data)
+}
+
+// checkScores refuses an AbuseIPDB score, of scores, read from data, as
+// reputationFile's check describes.
+func checkScores(scores []reputation.Score, data []byte) error {
+	var written struct {
+		AbuseIPDB struct {
+			Scores []struct {
+				Score *int64 `json:"score"`
+			} `json:"scores"`
+		} `json:"abuseipdb"`
+	}
+
+	err := json.Unmarshal(data, &written)
+	if err != nil {
+		return err
+	}
+
+	for i, kept := range scores {
+		switch {
+		case !kept.Client.IsValid():
+			return fmt.Errorf("abuseipdb scores %w", missing(i, "client"))
+		case written.AbuseIPDB.Scores[i].Score == nil:
+			return fmt.Errorf("abuseipdb scores %w", missing(i, "score"))
+		case kept.Fetched.IsZero():
+			return fmt.Errorf("abuseipdb scores %w", missing(i, "fetched"))
+		}
+	}
+
+	return nil
+}
+
 // check refuses a cooldown without its event or when its alert was sent,
 // which would hold back no repeat, alerts waiting for a destination with
-// another name than webhook, slack or ntfy, most likely misspelt, and an
-// alert waiting without its event or its time.
+// another name than webhook, slack or ntfy, most likely misspelt, an
+// alert waiting without its event or its time, and an anomaly counter as
+// checkAnomalyCounters does.
 func (f *alertsFile) check([]byte) error {
 	for i, cooldown := range f.Cooldowns {
 		switch {
@@ -694,11 +845,60 @@ func (f *alertsFile) check([]byte) error {
 		}
 	}
 
+	return checkAnomalyCounters(f.AnomalyCounters)
+}
+
+// checkAnomalyCounters refuses an anomaly counter whose scope is not
+// client, net, asn, total or watch, most likely misspelt, and one without
+// a field it needs, as missingFromCounter tells.
+func checkAnomalyCounters(counters []anomaly.Counter) error {
+	for i, counter := range counters {
+		if !slices.Contains(anomaly.Scopes(), counter.Scope) {
+			return fmt.Errorf("anomaly_counters entry %d's scope %q %w", i+1,
+				counter.Scope, errScope)
+		}
+
+		field := missingFromCounter(counter)
+		if field != "" {
+			return fmt.Errorf("anomaly_counters %w", missing(i, field))
+		}
+	}
+
 	return nil
 }
 
-// countsWithoutStart reports whether b holds requests but no start, which
-// places them in time.
+// missingFromCounter returns the first field counter, an anomaly counter,
+// needs and has not, or "" when it has them all: what tells it from the
+// others in its scope, without which it would never be counted again, the
+// netblock of a client, net or watch counter, the AS number of an asn one
+// and the name of a watch one; and the start of a window in which it has
+// requests or bytes, without which they would be dropped.
+func missingFromCounter(counter anomaly.Counter) string {
+	scope := counter.Scope
+
+	switch {
+	case scope != anomaly.ScopeASN && scope != anomaly.ScopeTotal &&
+		!counter.Netblock.IsValid():
+		return "netblock"
+	case scope == anomaly.ScopeASN && counter.ASN == "":
+		return "asn"
+	case scope == anomaly.ScopeWatch && counter.Name == "":
+		return "name"
+	case countsWithoutStart(counter.Minute):
+		return "minute.start"
+	case countsWithoutStart(counter.Hour):
+		return "hour.start"
+	case countsWithoutStart(counter.MinuteBytes):
+		return "minute_bytes.start"
+	case countsWithoutStart(counter.HourBytes):
+		return "hour_bytes.start"
+	default:
+		return ""
+	}
+}
+
+// countsWithoutStart reports whether b holds requests, or bytes, but no
+// start, which places them in time.
 func countsWithoutStart(b ratelimit.Buckets) bool {
 	return b.Start.IsZero() && (b.Current != 0 || b.Previous != 0)
 }

internal/state/state_test.go

@@ -22,19 +22,27 @@ import (
 	"time"
 
 	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/anomaly"
 	"sneak.berlin/go/smallwebwaf/internal/bans"
 	"sneak.berlin/go/smallwebwaf/internal/lookup"
 	"sneak.berlin/go/smallwebwaf/internal/metrics"
 	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
+	"sneak.berlin/go/smallwebwaf/internal/reputation"
 	"sneak.berlin/go/smallwebwaf/internal/state"
 )
 
 const (
 	// The state files.
-	bansJSON    = "bans.json"
-	clientsJSON = "clients.json"
-	lookupsJSON = "lookups.json"
-	alertsJSON  = "alerts.json"
+	bansJSON       = "bans.json"
+	clientsJSON    = "clients.json"
+	lookupsJSON    = "lookups.json"
+	reputationJSON = "reputation.json"
+	alertsJSON     = "alerts.json"
+	// blocklistURL and torURL are the blocklists the tests' lists name, and
+	// dnsblZone the DNSBL zone of the tests' verdicts.
+	blocklistURL = "https://lists.example/drop.txt"
+	torURL       = "https://lists.example/tor.txt"
+	dnsblZone    = "dnsbl.example"
 	// The AS number and AS name the tests' clients are looked up in.
 	asn    = "AS64496"
 	asName = "Example Net"
@@ -45,6 +53,9 @@ const (
 	// maxLogLines is how many lines of the process log wait for a test to
 	// read them.
 	maxLogLines = 64
+	// whole is the percentage of each limit a client gets when nothing
+	// lowers its limits.
+	whole = 100
 )
 
 // permanentBansJSON is bans.json holding permanentBan.
@@ -153,6 +164,104 @@ const filledAlertsJSON = `{
                 "suppressed_repeats": 0
             }
         ]
+    },
+    "anomaly_counters": [
+        {
+            "scope": "asn",
+            "asn": "AS64496",
+            "hour_bytes": {
+                "start": "2026-10-06T00:00:00Z",
+                "current": 8,
+                "previous": 0
+            }
+        },
+        {
+            "scope": "net",
+            "netblock": "203.0.113.0/24",
+            "minute": {
+                "start": "2026-10-06T00:00:00Z",
+                "current": 1,
+                "previous": 0
+            }
+        },
+        {
+            "scope": "total",
+            "minute": {
+                "start": "2026-10-06T00:00:00Z",
+                "current": 1,
+                "previous": 0
+            },
+            "minute_bytes": {
+                "start": "2026-10-06T00:00:00Z",
+                "current": 8,
+                "previous": 0
+            }
+        },
+        {
+            "scope": "watch",
+            "netblock": "203.0.113.0/24",
+            "name": "office",
+            "hour": {
+                "start": "2026-10-06T00:00:00Z",
+                "current": 1,
+                "previous": 0
+            }
+        }
+    ]
+}
+`
+
+// filledReputationJSON is reputation.json holding the blocklists' last
+// tries and the copy of one, with its comment line, two verdicts of a
+// DNSBL zone, and the AbuseIPDB checks spent today with two scores, as
+// fill puts them in.
+const filledReputationJSON = `{
+    "version": 1,
+    "lists": [
+        {
+            "url": "https://lists.example/drop.txt",
+            "tried": "2026-10-06T00:00:00Z",
+            "fetched": "2026-10-05T23:00:00Z",
+            "lines": [
+                "; Spamhaus DROP List 2026/10/05 - (c) 2026 The Spamhaus Project SLL",
+                "203.0.113.0/24 ; SBL1",
+                "2001:db8::/32 ; SBL2"
+            ]
+        },
+        {
+            "url": "https://lists.example/tor.txt",
+            "tried": "2026-10-06T00:00:00Z"
+        }
+    ],
+    "verdicts": [
+        {
+            "zone": "dnsbl.example",
+            "client": "203.0.113.9",
+            "listed": true,
+            "fetched": "2026-10-05T23:00:00Z"
+        },
+        {
+            "zone": "dnsbl.example",
+            "client": "2001:db8::1",
+            "listed": false,
+            "fetched": "2026-10-05T22:00:00Z"
+        }
+    ],
+    "abuseipdb": {
+        "day": "2026-10-06T00:00:00Z",
+        "spent": 3,
+        "scores": [
+            {
+                "client": "203.0.113.9/32",
+                "score": 100,
+                "fetched": "2026-10-05T23:00:00Z"
+            },
+            {
+                "client": "2001:db8::/64",
+                "score": 0,
+                "fetched": "2026-10-05T22:00:00Z"
+            }
+        ]
     }
 }
 `
@@ -183,18 +292,52 @@ func TestFilesWrittenAndReadBack(t *testing.T) {
 	wantEqual(t, clientsJSON, after.Limiter.Snapshot(), before.Limiter.Snapshot())
 	wantEqual(t, lookupsJSON, after.GeoJS.Snapshot(), before.GeoJS.Snapshot())
 
+	if got, want := after.Lists.Snapshot(), before.Lists.Snapshot(); !reflect.DeepEqual(
+		got, want) {
+		t.Errorf("%s read back\n%+v\nwant\n%+v", reputationJSON, got, want)
+	}
+
+	wantEqual(t, reputationJSON, after.DNSBL.Snapshot(), before.DNSBL.Snapshot())
+
+	checks, wantChecks := after.AbuseIPDB.Snapshot(), before.AbuseIPDB.Snapshot()
+	if !reflect.DeepEqual(checks, wantChecks) {
+		t.Errorf("%s read back\n%+v\nwant\n%+v", reputationJSON, checks, wantChecks)
+	}
+
 	if got, want := after.Alerts.Snapshot(), before.Alerts.Snapshot(); !reflect.DeepEqual(
 		got, want) {
 		t.Errorf("%s read back\n%+v\nwant\n%+v", alertsJSON, got, want)
 	}
 
+	wantEqual(t, alertsJSON, after.Anomalies.Snapshot(), before.Anomalies.Snapshot())
+
 	// Each one-per-line file lists its entries by client, and nothing
-	// but the four files is left in the directory.
+	// but the five files is left in the directory.
 	wantEntries(t, filepath.Join(dir, clientsJSON), "clients",
 		"192.0.2.1/32", "203.0.113.9/32", "2001:db8::/64")
 	wantEntries(t, filepath.Join(dir, lookupsJSON), "lookups",
 		"192.0.2.1/32", "203.0.113.9/32")
-	wantFiles(t, dir, alertsJSON, bansJSON, clientsJSON, lookupsJSON)
+	wantFiles(t, dir, alertsJSON, bansJSON, clientsJSON, lookupsJSON, reputationJSON)
+}
+
+func TestReputationJSONKeepsEachCopyWholeOneLineToALine(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	params := newParams(dir)
+	fill(params)
+
+	files := load(t, params)
+
+	err := files.WriteAll()
+	if err != nil {
+		t.Fatalf("write: %v", err)
+	}
+
+	got := readFile(t, filepath.Join(dir, reputationJSON))
+	if got != filledReputationJSON {
+		t.Errorf("reputation.json\n%s\nwant\n%s", got, filledReputationJSON)
+	}
 }
 
 func TestAlertsJSONIsIndentedWithTheCooldownsTheHourAndTheAlertsWaiting(t *testing.T) {
@@ -248,6 +391,49 @@ func TestSourceFailureCooldownKeptInAlertsJSONAcrossARestart(t *testing.T) {
 	}
 }
 
+func TestAnomalyCountersKeptInAlertsJSONAcrossARestart(t *testing.T) {
+	t.Parallel()
+
+	dir := t.TempDir()
+	request := anomaly.Request{
+		Client:      netip.MustParseAddr("203.0.113.9"),
+		ClientGroup: netip.MustParsePrefix("203.0.113.9/32"),
+	}
+
+	// The whole service may have two requests a minute.
+	withThreshold := func() state.Params {
+		params := newParams(dir)
+		params.Anomalies = anomaly.New(anomaly.Params{
+			Total: anomaly.Thresholds{RequestsPerMinute: 2}, Alerts: params.Alerts,
+		})
+
+		return params
+	}
+
+	before := withThreshold()
+	files := load(t, before)
+
+	for range 2 {
+		before.Anomalies.Count(midnight(), request)
+	}
+
+	err := files.WriteAll()
+	if err != nil {
+		t.Fatalf("write: %v", err)
+	}
+
+	// After the restart, the third request in the minute is over it.
+	after := withThreshold()
+	load(t, after)
+	after.Anomalies.Count(midnight(), request)
+
+	waiting := after.Alerts.Snapshot().Waiting[alerts.DestinationWebhook]
+	if len(waiting) != 1 || waiting[0].Event != alerts.EventAnomaly ||
+		waiting[0].Detail["count"] != float64(3) {
+		t.Errorf("alerts wait %+v, want one for 3 requests", waiting)
+	}
+}
+
 func TestBansJSONIsIndentedWithNullForAPermanentBan(t *testing.T) {
 	t.Parallel()
 
@@ -275,9 +461,13 @@ func TestMissingFilesAreEmptyState(t *testing.T) {
 	load(t, params)
 
 	held := params.Alerts.Snapshot()
+	checks := params.AbuseIPDB.Snapshot()
+
 	if len(params.Ledger.Snapshot()) != 0 || len(params.Limiter.Snapshot()) != 0 ||
-		len(params.GeoJS.Snapshot()) != 0 || len(held.Cooldowns) != 0 ||
-		len(held.Waiting[alerts.DestinationWebhook]) != 0 || held.Hour.Sent != 0 {
+		len(params.GeoJS.Snapshot()) != 0 || len(params.Lists.Snapshot()) != 0 ||
+		len(params.DNSBL.Snapshot()) != 0 || len(checks.Scores) != 0 || checks.Spent != 0 ||
+		len(held.Cooldowns) != 0 || len(held.Waiting[alerts.DestinationWebhook]) != 0 ||
+		held.Hour.Sent != 0 {
 		t.Error("state from no files")
 	}
 }
@@ -329,6 +519,21 @@ func TestFileThatDoesNotParseStopsTheStart(t *testing.T) {
 			`{"version": 1, "waiting": {"webhook": [], "slak": []}}`,
 			`: waiting "slak" is not webhook, slack or ntfy`,
 		},
+		{
+			"an anomaly counter of an unknown scope", alertsJSON,
+			`{"version": 1, "anomaly_counters": [{"scope": "total"}, ` +
+				`{"scope": "nett", "netblock": "203.0.113.0/24"}]}`,
+			`: anomaly_counters entry 2's scope "nett" is not client, net, asn, total ` +
+				`or watch`,
+		},
+		{
+			"a copy of a list with a line that does not read", reputationJSON,
+			`{"version": 1, "lists": [{"url": "` + blocklistURL + `", ` +
+				`"tried": "2026-10-06T00:00:00Z", "fetched": "2026-10-06T00:00:00Z", ` +
+				`"lines": ["; DROP", "203.0.113.300"]}]}`,
+			`: the copy of ` + blocklistURL + `: line 2 is not an address or a netblock, ` +
+				`such as 192.0.2.0/24`,
+		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
@@ -392,6 +597,12 @@ func TestEntryWithoutAFieldItNeedsStopsTheStart(t *testing.T) {
 				`"hour": {"current": 3}}]}`,
 			`: entry 1 has no "hour.start"`,
 		},
+		{
+			"a client with bytes in a window without its start", clientsJSON,
+			`{"version": 1, "clients": [{"client": "203.0.113.9/32", ` +
+				`"minute_bytes": {"previous": 5120}}]}`,
+			`: entry 1 has no "minute_bytes.start"`,
+		},
 		{
 			"an answer without a client", lookupsJSON,
 			`{"version": 1, "lookups": [{"country": "DE", ` + answer + `}]}`,
@@ -418,6 +629,121 @@ func TestEntryWithoutAFieldItNeedsStopsTheStart(t *testing.T) {
 	}
 }
 
+func TestReputationJSONEntryWithoutAFieldItNeedsStopsTheStart(t *testing.T) {
+	t.Parallel()
+
+	const (
+		drop    = `"url": "` + blocklistURL + `", `
+		tried   = `"tried": "2026-10-06T00:00:00Z", `
+		fetched = `"fetched": "2026-10-06T00:00:00Z"`
+		// verdictZone, verdictClient and listed start a verdict, which
+		// fetched ends.
+		verdictZone   = `"zone": "` + dnsblZone + `", `
+		verdictClient = `"client": "198.51.100.7", `
+		listed        = `"listed": false, `
+	)
+
+	for _, tc := range []struct {
+		name, content string
+		// want is what the error says after the file's path.
+		want string
+	}{
+		{
+			"a list without its URL",
+			`{"version": 1, "lists": [{` + tried + fetched + `, "lines": []}]}`,
+			`: entry 1 has no "url"`,
+		},
+		{
+			"a list without the time it was last tried",
+			`{"version": 1, "lists": [{` + drop + fetched + `, "lines": []}]}`,
+			`: entry 1 has no "tried"`,
+		},
+		{
+			"a copy of a list without the time it was fetched",
+			`{"version": 1, "lists": [{` + drop + tried + `"lines": []}]}`,
+			`: entry 1 has no "fetched"`,
+		},
+		{
+			// An empty list has no lines, which is not having none.
+			"a copy of a list without its lines",
+			`{"version": 1, "lists": [{` + drop + tried + fetched + `, "lines": []}, ` +
+				`{"url": "` + torURL + `", ` + tried + fetched + `}]}`,
+			`: entry 2 has no "lines"`,
+		},
+		{
+			"a verdict without its zone",
+			`{"version": 1, "verdicts": [{` + verdictClient + listed + fetched + `}]}`,
+			`: verdicts entry 1 has no "zone"`,
+		},
+		{
+			"a verdict without its client",
+			`{"version": 1, "verdicts": [{` + verdictZone + listed + fetched + `}]}`,
+			`: verdicts entry 1 has no "client"`,
+		},
+		{
+			// A client the zone does not list has a listed of false, which is
+			// not having none.
+			"a verdict without whether the zone lists the client",
+			`{"version": 1, "verdicts": [{` + verdictZone + verdictClient + listed +
+				fetched + `}, {` + verdictZone + verdictClient + fetched + `}]}`,
+			`: verdicts entry 2 has no "listed"`,
+		},
+		{
+			"a verdict without the time it was fetched",
+			`{"version": 1, "verdicts": [{` + verdictZone + verdictClient +
+				`"listed": true}]}`,
+			`: verdicts entry 1 has no "fetched"`,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			wantRefused(t, reputationJSON, tc.content, tc.want)
+		})
+	}
+}
+
+func TestReputationJSONScoreWithoutAFieldItNeedsStopsTheStart(t *testing.T) {
+	t.Parallel()
+
+	// scores opens the list of AbuseIPDB scores, and ends closes it; client,
+	// score and fetched make a score.
+	const (
+		scores  = `{"version": 1, "abuseipdb": {"scores": [`
+		client  = `"client": "198.51.100.7/32", `
+		score   = `"score": 0, `
+		fetched = `"fetched": "2026-10-06T00:00:00Z"`
+		ends    = `}]}}`
+	)
+
+	for _, tc := range []struct {
+		name, content string
+		// want is what the error says after the file's path.
+		want string
+	}{
+		{
+			"without its client", scores + `{` + score + fetched + ends,
+			`: abuseipdb scores entry 1 has no "client"`,
+		},
+		{
+			// A score of 0 is not having none.
+			"without the score",
+			scores + `{` + client + score + fetched + `}, {` + client + fetched + ends,
+			`: abuseipdb scores entry 2 has no "score"`,
+		},
+		{
+			"without the time it was fetched", scores + `{` + client + `"score": 100` + ends,
+			`: abuseipdb scores entry 1 has no "fetched"`,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			wantRefused(t, reputationJSON, tc.content, tc.want)
+		})
+	}
+}
+
 func TestAlertsJSONEntryWithoutAFieldItNeedsStopsTheStart(t *testing.T) {
 	t.Parallel()
 
@@ -446,6 +772,39 @@ func TestAlertsJSONEntryWithoutAFieldItNeedsStopsTheStart(t *testing.T) {
 			`{"version": 1, "waiting": {"slack": [{"event": "ban"}]}}`,
 			`: waiting slack entry 1 has no "time"`,
 		},
+		{
+			// The whole service's counter needs nothing to tell it apart.
+			"an anomaly counter of a netblock without it",
+			`{"version": 1, "anomaly_counters": [{"scope": "total"}, {"scope": "net"}]}`,
+			`: anomaly_counters entry 2 has no "netblock"`,
+		},
+		{
+			"an anomaly counter of a client without its netblock",
+			`{"version": 1, "anomaly_counters": [{"scope": "client"}]}`,
+			`: anomaly_counters entry 1 has no "netblock"`,
+		},
+		{
+			"an anomaly counter of an AS number without it",
+			`{"version": 1, "anomaly_counters": [{"scope": "asn"}]}`,
+			`: anomaly_counters entry 1 has no "asn"`,
+		},
+		{
+			"an anomaly counter of a named netblock without its name",
+			`{"version": 1, "anomaly_counters": [` +
+				`{"scope": "watch", "netblock": "203.0.113.0/24"}]}`,
+			`: anomaly_counters entry 1 has no "name"`,
+		},
+		{
+			"an anomaly counter of a named netblock without its netblock",
+			`{"version": 1, "anomaly_counters": [{"scope": "watch", "name": "office"}]}`,
+			`: anomaly_counters entry 1 has no "netblock"`,
+		},
+		{
+			"an anomaly counter with bytes in a window without its start",
+			`{"version": 1, "anomaly_counters": [` +
+				`{"scope": "total", "hour_bytes": {"current": 5}}]}`,
+			`: anomaly_counters entry 1 has no "hour_bytes.start"`,
+		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
@@ -488,7 +847,9 @@ func TestBanWithAnotherCauseStopsTheStart(t *testing.T) {
 func TestUnknownVersionStopsTheStart(t *testing.T) {
 	t.Parallel()
 
-	for _, file := range []string{bansJSON, clientsJSON, lookupsJSON, alertsJSON} {
+	for _, file := range []string{
+		bansJSON, clientsJSON, lookupsJSON, reputationJSON, alertsJSON,
+	} {
 		for _, content := range []string{`{"version": 2}`, `{}`} {
 			t.Run(file+" "+content, func(t *testing.T) {
 				t.Parallel()
@@ -590,8 +951,9 @@ func TestEveryFileWrittenEveryCounterInterval(t *testing.T) {
 
 			time.Sleep(time.Nanosecond)
 			synctest.Wait()
-			wantFiles(t, dir, alertsJSON, bansJSON, clientsJSON, lookupsJSON)
-			removeFiles(t, dir, alertsJSON, bansJSON, clientsJSON, lookupsJSON)
+			wantFiles(t, dir, alertsJSON, bansJSON, clientsJSON, lookupsJSON, reputationJSON)
+			removeFiles(t, dir, alertsJSON, bansJSON, clientsJSON, lookupsJSON,
+				reputationJSON)
 		}
 	})
 }
@@ -707,7 +1069,7 @@ func TestFailedWriteLeavesTheFileAsItWas(t *testing.T) {
 
 	params.Ledger.BanForLimit(netip.MustParsePrefix("203.0.113.9/32"), midnight(),
 		bans.Notes{})
-	params.Limiter.Count(netip.MustParsePrefix("203.0.113.9/32"), midnight())
+	params.Limiter.Count(netip.MustParsePrefix("203.0.113.9/32"), midnight(), whole)
 
 	err = files.WriteAll()
 	if err == nil || !strings.Contains(err.Error(), bansJSON+".tmp") {
@@ -810,7 +1172,7 @@ func TestFileThatCannotBeReadIsNotWrittenOver(t *testing.T) {
 		t.Errorf("bans.json is now %v (%v), want the socket", info, err)
 	}
 
-	wantFiles(t, dir, alertsJSON, bansJSON, clientsJSON, lookupsJSON)
+	wantFiles(t, dir, alertsJSON, bansJSON, clientsJSON, lookupsJSON, reputationJSON)
 	wantWriteFailed(t, params, bansJSON)
 }
 
@@ -883,6 +1245,32 @@ func TestEditOfEachFileTakenIn(t *testing.T) {
 	wantEqual(t, lookupsJSON, params.GeoJS.Snapshot(),
 		[]lookup.Answer{{Client: client, Country: "FR", Answered: midnight()}})
 
+	edit(t, dir, reputationJSON, `{"version": 1, "lists": [{"url": "`+blocklistURL+`", `+
+		`"tried": "2026-10-06T00:00:00Z", "fetched": "2026-10-06T00:00:00Z", `+
+		`"lines": ["198.51.100.7"]}], "verdicts": [{"zone": "`+dnsblZone+`", `+
+		`"client": "198.51.100.7", "listed": true, "fetched": "2026-10-06T00:00:00Z"}], `+
+		`"abuseipdb": {"day": "2026-10-06T00:00:00Z", "spent": 9, "scores": [`+
+		`{"client": "198.51.100.7/32", "score": 80, "fetched": "2026-10-06T00:00:00Z"}]}}`)
+	wantTakenIn(t, lines, dir, reputationJSON)
+
+	listedBy := params.Lists.ListedBy(client.Addr())
+	if !slices.Equal(listedBy, []string{blocklistURL}) {
+		t.Errorf("%s taken in lists %s on %v, want on the blocklist", reputationJSON,
+			client.Addr(), listedBy)
+	}
+
+	wantEqual(t, reputationJSON, params.DNSBL.Snapshot(), []reputation.Verdict{{
+		Zone: dnsblZone, Client: client.Addr(), Listed: true, Fetched: midnight(),
+	}})
+
+	checks := reputation.Checks{
+		Day: midnight(), Spent: 9,
+		Scores: []reputation.Score{{Client: client, Score: 80, Fetched: midnight()}},
+	}
+	if got := params.AbuseIPDB.Snapshot(); !reflect.DeepEqual(got, checks) {
+		t.Errorf("%s taken in as\n%+v\nwant\n%+v", reputationJSON, got, checks)
+	}
+
 	// A netblock with bits past its length is read as the netblock it is
 	// in.
 	edit(t, dir, alertsJSON, `{"version": 1, "cooldowns": [{"event": "ban", `+
@@ -1110,7 +1498,7 @@ func TestBrokenEditSetAsideAtTheNextWrite(t *testing.T) {
 	edit(t, dir, bansJSON, broken)
 	edit(t, dir, clientsJSON, `{"version": 1, "clients": []}`)
 	wantTakenIn(t, lines, dir, clientsJSON)
-	wantFiles(t, dir, alertsJSON, bansJSON, clientsJSON, lookupsJSON)
+	wantFiles(t, dir, alertsJSON, bansJSON, clientsJSON, lookupsJSON, reputationJSON)
 
 	// The next write sets it aside, logged with where the error is, and
 	// writes bans.json again from what smallwebwaf still holds.
@@ -1134,7 +1522,8 @@ func TestBrokenEditSetAsideAtTheNextWrite(t *testing.T) {
 		t.Errorf("alerts waiting %+v, want a file_error alert for %s", waiting, path+".bad")
 	}
 
-	wantFiles(t, dir, alertsJSON, bansJSON, bansJSON+".bad", clientsJSON, lookupsJSON)
+	wantFiles(t, dir, alertsJSON, bansJSON, bansJSON+".bad", clientsJSON, lookupsJSON,
+		reputationJSON)
 
 	if got := readFile(t, path+".bad"); got != broken {
 		t.Errorf("bans.json.bad holds\n%s\nwant the edit", got)
@@ -1263,11 +1652,21 @@ func midnight() time.Time {
 }
 
 // newParams returns Params for the state files in dir, with parts that
-// hold nothing yet. GeoJS is never asked, and the alerts, at most two an
-// hour, are never sent.
+// hold nothing yet. GeoJS is never asked, the lists, two blocklists, are
+// never fetched, and the alerts, at most two an hour, are
+// never sent. The anomaly counters count the scopes fill counts, with
+// thresholds fill does not reach.
 func newParams(dir string) state.Params {
 	discard := slog.New(slog.DiscardHandler)
 	m := metrics.New(1, "app")
+	queue := alerts.New(alerts.Params{
+		WebhookURL: &url.URL{Scheme: "https", Host: "alerts.example"},
+		Events:     alerts.Events(),
+		Cooldown:   15 * time.Minute,
+		MaxPerHour: 2,
+		Instance:   "fsn1app1/gitea",
+		Now:        midnight,
+	})
 
 	return state.Params{
 		Dir:             dir,
@@ -1284,13 +1683,28 @@ func newParams(dir string) state.Params {
 		GeoJS: lookup.New(lookup.Params{
 			Now: midnight, ProcessLog: discard, Metrics: m,
 		}),
-		Alerts: alerts.New(alerts.Params{
-			WebhookURL: &url.URL{Scheme: "https", Host: "alerts.example"},
-			Events:     alerts.Events(),
-			Cooldown:   15 * time.Minute,
-			MaxPerHour: 2,
-			Instance:   "fsn1app1/gitea",
-			Now:        midnight,
+		Lists: reputation.New(reputation.Params{
+			BlocklistURLs: []string{blocklistURL, torURL}, Refresh: 24 * time.Hour,
+			Now: midnight, ProcessLog: discard, Alerts: queue,
+		}),
+		DNSBL: reputation.NewDNSBL(reputation.DNSBLParams{
+			Zones: []string{dnsblZone}, CacheTTL: 24 * time.Hour, Timeout: time.Second,
+			Now: midnight, ProcessLog: discard, Alerts: queue,
+		}),
+		AbuseIPDB: reputation.NewAbuseIPDB(reputation.AbuseIPDBParams{
+			MinScore: 75, DailyBudget: 900, CacheTTL: 24 * time.Hour, Timeout: time.Second,
+			Now: midnight, ProcessLog: discard, Alerts: queue,
+		}),
+		Alerts: queue,
+		Anomalies: anomaly.New(anomaly.Params{
+			Net:            anomaly.Thresholds{RequestsPerMinute: 1000},
+			ASN:            anomaly.Thresholds{BytesPerHour: 1 << 30},
+			Total:          anomaly.Thresholds{RequestsPerMinute: 1000, BytesPerMinute: 1 << 30},
+			Watch:          anomaly.Thresholds{RequestsPerHour: 1000},
+			NetV4Prefix:    24,
+			NetV6Prefix:    48,
+			NamedNetblocks: []anomaly.NamedNetblock{{Name: "office", Netblock: office()}},
+			Alerts:         queue,
 		}),
 		Now:        midnight,
 		ProcessLog: discard,
@@ -1298,10 +1712,18 @@ func newParams(dir string) state.Params {
 	}
 }
 
+// office is the named netblock of the anomaly counters of newParams.
+func office() netip.Prefix {
+	return netip.MustParsePrefix("203.0.113.0/24")
+}
+
 // fill puts a permanent ban an admin made, a ban for a broken limit and
 // one for a clear sign of attack, clients with counts and histories,
-// GeoJS answers, and alerts, as filledAlertsJSON holds them, into the
-// parts of params.
+// GeoJS answers, the blocklists' last tries and the copy of one, two
+// verdicts of a DNSBL zone, and the AbuseIPDB checks spent today with two
+// scores, as filledReputationJSON holds them, and alerts
+// and anomaly counters, as filledAlertsJSON holds them, into the parts of
+// params.
 func fill(params state.Params) {
 	now := midnight()
 	client := netip.MustParsePrefix("203.0.113.9/32")
@@ -1314,9 +1736,10 @@ func fill(params state.Params) {
 		bans.Notes{RuleID: "env-file", Target: "path"})
 
 	for _, c := range []string{"2001:db8::/64", "203.0.113.9/32", "192.0.2.1/32"} {
-		params.Limiter.Count(netip.MustParsePrefix(c), now)
+		params.Limiter.Count(netip.MustParsePrefix(c), now, whole)
 	}
 
+	params.Limiter.CountBytes(client, now, 8, whole)
 	params.Limiter.AddToHistory(client, now, ratelimit.Request{
 		Forwarded: true, Status: 200, RequestBytes: 3, ResponseBytes: 5,
 	})
@@ -1333,6 +1756,32 @@ func fill(params state.Params) {
 		},
 	})
 
+	// The copy of drop.txt was fetched an hour ago, and the fetches of it
+	// and of tor.txt tried since failed.
+	err := params.Lists.Load([]reputation.List{{
+		URL: blocklistURL, Tried: now, Fetched: now.Add(-time.Hour),
+		Lines: []string{
+			"; Spamhaus DROP List 2026/10/05 - (c) 2026 The Spamhaus Project SLL",
+			"203.0.113.0/24 ; SBL1",
+			"2001:db8::/32 ; SBL2",
+		},
+	}, {URL: torURL, Tried: now}})
+	if err != nil {
+		panic(err) // the copy reads
+	}
+
+	params.DNSBL.Load([]reputation.Verdict{
+		{
+			Zone: dnsblZone, Client: netip.MustParseAddr("2001:db8::1"),
+			Fetched: now.Add(-2 * time.Hour),
+		},
+		{Zone: dnsblZone, Client: client.Addr(), Listed: true, Fetched: now.Add(-time.Hour)},
+	})
+	params.AbuseIPDB.Load(reputation.Checks{Day: now, Spent: 3, Scores: []reputation.Score{
+		{Client: netip.MustParsePrefix("2001:db8::/64"), Fetched: now.Add(-2 * time.Hour)},
+		{Client: client, Score: 100, Fetched: now.Add(-time.Hour)},
+	}})
+
 	// An alert waiting, a repeat of it the cooldown holds back, another
 	// alert waiting, and one past the two an hour, for the hour's summary.
 	ban := alerts.Alert{
@@ -1351,6 +1800,10 @@ func fill(params state.Params) {
 	params.Alerts.Raise(alerts.Alert{
 		Event: alerts.EventSourceFailure, Reason: "asking GeoJS failed",
 	})
+
+	params.Anomalies.Count(now, anomaly.Request{
+		Client: client.Addr(), ClientGroup: client, ASN: asn, Bytes: 8,
+	})
 }
 
 // permanentBan is the ban permanentBansJSON holds.