Bans an admin makes or lifts: the admin cause, a reason, lifted bans kept (closes #86)

A bans.json entry without a cause gets the cause admin, written back so.
Bans whose cause is admin are never dropped and do not count toward
SWWAF_MAX_BANS, so setting a ban's cause to admin keeps it. Bans
smallwebwaf makes get a reason: the limit broken or the rule matched. A
lifted ban refuses nothing, is kept, and makes no later ban longer.
smallwebwaf_bans_made_total counts admin bans an edit adds while running;
earlier_bans counts admin in place of without_cause.

Judgement call: lifted lifts at once, whatever time it gives.
Judgement call: a lifted ban still counts in earlier_bans.
Known gap: a ban dropped from behind an admin's ban on its netblock leaves that netblock's later earlier_bans.

Model: opus-5-5

internal/proxy/bans_test.go

@@ -279,6 +279,7 @@ func TestBanNotes(t *testing.T) {
 		Start:    start,
 		Expires:  start.Add(time.Hour),
 		Cause:    bans.CauseLimit,
+		Reason:   "requests per minute over the limit of 1",
 		Notes: bans.Notes{
 			Country: "DE",
 			Limit:   1,

internal/proxy/metrics_test.go

@@ -12,6 +12,7 @@ import (
 	"testing"
 	"time"
 
+	"sneak.berlin/go/smallwebwaf/internal/bans"
 	"sneak.berlin/go/smallwebwaf/internal/lookup"
 	"sneak.berlin/go/smallwebwaf/internal/proxy"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
@@ -243,6 +244,29 @@ func TestMetricsCountLimitsAndBans(t *testing.T) {
 	wantMetric(t, metrics, "smallwebwaf_tracked_clients", 3)
 }
 
+func TestMetricsCountTheBansAnAdminMakes(t *testing.T) {
+	t.Parallel()
+
+	const scraper = "192.0.2.200" // in SWWAF_RATE_LIMIT_EXEMPT_NETS
+
+	s, clk, server := startWithClock(t, "", map[string]string{
+		metricsToken:        token,
+		rateLimitExemptNets: scraper,
+	})
+
+	const admins = `smallwebwaf_bans_made_total{cause="admin"}`
+
+	wantMetric(t, s.scrape(scraper), admins, 0)
+
+	// As an admin's edit of bans.json that adds a ban is taken in.
+	server.Ledger.LoadEdit([]bans.Ban{{
+		Netblock: netip.MustParsePrefix(client + "/32"),
+		Start:    clk.Now(),
+	}})
+
+	wantMetric(t, s.scrape(scraper), admins, 1)
+}
+
 func TestMetricsByCountryKeepTheBusiestAndCountTheRestAsOther(t *testing.T) {
 	t.Parallel()
 

internal/proxy/observe_test.go

@@ -95,6 +95,7 @@ func TestObserveModeMakesNoBanAndKeepsTheBansItHas(t *testing.T) {
 		Netblock: netip.MustParsePrefix(otherClient + "/32"),
 		Start:    clk.Now(),
 		Expires:  clk.Now().Add(time.Hour),
+		Cause:    bans.CauseAdmin,
 	}
 	server.Ledger.Load([]bans.Ban{kept})
 

internal/proxy/rulefiles_test.go

@@ -55,6 +55,7 @@ func TestEachRuleAction(t *testing.T) {
 		Start:    start,
 		Expires:  start.Add(7 * 24 * time.Hour),
 		Cause:    bans.CauseAttack,
+		Reason:   "matched the rule probe",
 		Notes: bans.Notes{
 			RuleID: "probe",
 			Target: "path",