smallwebwaf/internal/discriminator/crowdsec_test.go

package discriminator_test

import (
	"net/http"
	"net/netip"
	"reflect"
	"testing"
	"time"

	"sneak.berlin/go/smallwebwaf/internal/alerts"
	"sneak.berlin/go/smallwebwaf/internal/bans"
	"sneak.berlin/go/smallwebwaf/internal/discriminator"
	"sneak.berlin/go/smallwebwaf/internal/reputation"
	"sneak.berlin/go/smallwebwaf/internal/requestlog"
)

// The CrowdSec settings, and the tests' engine, which is never asked: each
// test puts in the copy of its decision list, at decisionsURL, that it
// needs, as reputation.json would at start.
const (
	crowdSecURL  = "SWW_WAF_CROWDSEC_LAPI_URL"
	crowdSecKey  = "SWW_WAF_CROWDSEC_LAPI_KEY"
	lapi         = "http://crowdsec.example:8080"
	decisionsURL = lapi + "/v1/decisions"
	bouncerKey   = "crowdsec-key-0123456789abcdef"
)

func TestClientTheCrowdSecDecisionListListsIsBannedUntilTheDecisionEnds(t *testing.T) {
	t.Parallel()

	s, clk, server, queue := startWithAlerts(t, map[string]string{
		crowdSecURL: lapi, crowdSecKey: bouncerKey, metricsToken: token,
	})
	// client had four hours left on its decision as the engine answered.
	fetched := clk.Now()
	loadDecisions(t, server, fetched, `[{"duration": "4h0m0s", `+
		`"scenario": "crowdsecurity/ssh-bf", "scope": "Ip", "type": "ban", `+
		`"value": "`+client+`"}]`)
	expires := requestlog.FormatTime(fetched.Add(4 * time.Hour))

	// Its first request is refused, and bans it until the decision ends.
	line := s.get(client, http.StatusForbidden, requestlog.ActionBanned)
	wantReputation(t, line, decisionsURL)

	if line.BanExpires != expires {
		t.Errorf("log line has ban_expires %q, want %s", line.BanExpires, expires)
	}

	listed := []bans.ReputationHit{{Source: decisionsURL}}

	held := server.Ledger.Bans(netip.MustParsePrefix(client + "/32"))
	if len(held) != 1 || held[0].Cause != bans.CauseCrowdSec ||
		!held[0].Start.Equal(fetched) || !held[0].Expires.Equal(fetched.Add(4*time.Hour)) ||
		held[0].Reason != "CrowdSec's decision for crowdsecurity/ssh-bf" ||
		!reflect.DeepEqual(held[0].Notes.Reputation, listed) ||
		held[0].Notes.Request.Path != "/" || held[0].Notes.Requests != 1 {
		t.Fatalf("bans %+v, want one for crowdsec of four hours, with the list and "+
			"the request in its notes", held)
	}

	// The listing raises a reputation_hit alert, and the ban its own.
	waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
	if len(waiting) != 2 || waiting[0].Event != alerts.EventReputationHit ||
		waiting[0].Reason != "listed by the CrowdSec decision list" ||
		!reflect.DeepEqual(waiting[1], banAlert(alerts.EventBan, fetched, client, held[0],
			expires)) {
		t.Errorf("alerts waiting %+v, want a reputation_hit alert, then the ban's",
			waiting)
	}

	// Each request while the ban lasts is refused under it, as under any
	// ban, and once it has ended the client is let through.
	clk.advance(4*time.Hour - time.Second)

	line = s.get(client, http.StatusForbidden, requestlog.ActionBanned)
	wantReputation(t, line)

	if line.BanExpires != expires {
		t.Errorf("log line has ban_expires %q, want %s", line.BanExpires, expires)
	}

	clk.advance(time.Second)
	s.get(client, http.StatusOK, requestlog.ActionForward)

	// The ban and the hit are counted, and the list has the metrics of any
	// list fetched from a URL.
	metrics := s.scrape()
	labels := `{instance="` + alertInstance + `",source="` + decisionsURL + `"}`

	wantMetric(t, metrics, `sww_bans_made_total{cause="crowdsec",`+
		`instance="`+alertInstance+`"}`, 1)
	wantMetric(t, metrics, "sww_reputation_hits_total"+labels, 1)
	wantMetric(t, metrics, "sww_reputation_failures_total"+labels, 0)
	wantMetric(t, metrics, "sww_reputation_last_fetch_timestamp_seconds"+labels,
		float64(fetched.Unix()))
}

func TestEndedCrowdSecDecisionNoLongerBansThoughTheCopyStillHoldsIt(t *testing.T) {
	t.Parallel()

	s, clk, server := startWithClock(t, "", map[string]string{
		crowdSecURL: lapi, crowdSecKey: bouncerKey,
	})
	// 198.51.100.0/24 and 2001:db8::9 had a minute left as the engine
	// answered.
	fetched := clk.Now()
	loadDecisions(t, server, fetched, `[{"duration": "1m0s", `+
		`"scenario": "crowdsecurity/http-probing", "scope": "Range", "type": "ban", `+
		`"value": "198.51.100.0/24"}, {"duration": "1m0s", `+
		`"scenario": "crowdsecurity/http-probing", "scope": "Ip", "type": "ban", `+
		`"value": "2001:db8::9"}]`)

	// Just before its end, the decision bans a client in the netblock, and
	// one on an IPv6 address bans the address's group, the /64.
	clk.advance(time.Minute - time.Nanosecond)
	s.get("198.51.100.7", http.StatusForbidden, requestlog.ActionBanned)
	s.get("2001:db8::9", http.StatusForbidden, requestlog.ActionBanned)
	s.get("2001:db8::5", http.StatusForbidden, requestlog.ActionBanned)

	// Once it has ended, it bans no other client, and the bans it made end
	// with it.
	clk.advance(time.Nanosecond)

	for _, from := range []string{"198.51.100.8", "198.51.100.7", "2001:db8::5"} {
		wantReputation(t, s.get(from, http.StatusOK, requestlog.ActionForward))
	}

	if made := server.Ledger.Made(bans.CauseCrowdSec); made != 2 {
		t.Errorf("%d bans made for crowdsec, want 2, on 198.51.100.7/32 and "+
			"2001:db8::/64", made)
	}

	if held := server.Ledger.Bans(netip.MustParsePrefix("2001:db8::/64")); len(held) != 1 {
		t.Errorf("bans of 2001:db8::/64 %+v, want one", held)
	}
}

func TestObserveModeForwardsAClientTheCrowdSecDecisionListListsAndAlertsTheBan(
	t *testing.T,
) {
	t.Parallel()

	s, clk, server, queue := startWithAlerts(t, map[string]string{
		crowdSecURL: lapi, crowdSecKey: bouncerKey, mode: observe,
	})
	loadDecisions(t, server, clk.Now(), `[{"duration": "4h0m0s", `+
		`"scenario": "crowdsecurity/ssh-bf", "scope": "Ip", "type": "ban", `+
		`"value": "`+client+`"}]`)

	line := s.get(client, http.StatusOK, requestlog.ActionForward)
	wantWouldAction(t, line, requestlog.ActionBanned)
	wantReputation(t, line, decisionsURL)

	if held := server.Ledger.Snapshot(); len(held) != 0 {
		t.Errorf("bans %+v, want none", held)
	}

	waiting := queue.Snapshot().Waiting[alerts.DestinationWebhook]
	if len(waiting) != 2 || waiting[1].Event != alerts.EventBan ||
		waiting[1].Detail["cause"] != bans.CauseCrowdSec ||
		waiting[1].Detail["mode"] != observe {
		t.Errorf("alerts waiting %+v, want a reputation_hit alert, then the ban alert "+
			"marked observe", waiting)
	}
}

// loadDecisions puts into server's lists the copy of the decision list at
// decisionsURL, answer, the engine's answer, fetched at fetched, as
// reputation.json would at start.
func loadDecisions(
	t *testing.T, server *discriminator.Server, fetched time.Time, answer string,
) {
	t.Helper()

	err := server.Lists.Load([]reputation.List{{
		URL: decisionsURL, Tried: fetched, Fetched: fetched, Lines: []string{answer},
	}})
	if err != nil {
		t.Fatalf("load the decision list: %v", err)
	}
}