Alerts to a JSON webhook, with a cooldown and an hourly summary (closes #26)

SWWAF_ALERT_WEBHOOK_URL gets one JSON POST per alert, in SPEC.md's
schema, with SWWAF_ALERT_WEBHOOK_HEADERS: ban and permanent_ban, with
the ban's notes, in observe mode too, marked mode observe and worked
out only when the alert would be sent; source_failure for GeoJS;
file_error for a rule or state file with an error. SWWAF_ALERT_EVENTS
chooses; SWWAF_ALERT_COOLDOWN holds back repeats by netblock, file or
source; past SWWAF_ALERT_MAX_PER_HOUR the hour ends in one summary. A
bounded queue, retried with backoff, holds up no request; a 4xx other
than 408 and 429 gives the alert up. alerts.json keeps the queue, the
cooldowns and the hour. Nothing shows the URL's path or query.

Judgement call: the summary's event is summary, which SPEC.md omits.
Judgement call: an admin's ban raises no alert.

Model: opus-5-5

internal/alerts/alerts_test.go

@@ -118,6 +118,23 @@ func TestOnlyTheChosenEventsAreSent(t *testing.T) {
 	})
 }
 
+func TestWouldSendOnlyForTheChosenEvents(t *testing.T) {
+	t.Parallel()
+
+	params := newParams()
+	params.Events = []string{alerts.EventSourceFailure, alerts.EventFileError}
+	q := alerts.New(params)
+
+	if q.WouldSend(alerts.EventBan, netblock(1)) ||
+		q.WouldSend(alerts.EventPermanentBan, netblock(1)) {
+		t.Error("a ban alert would be sent, though SWWAF_ALERT_EVENTS leaves it out")
+	}
+
+	if !q.WouldSend(alerts.EventFileError, netip.Prefix{}) {
+		t.Error("a file_error alert would not be sent")
+	}
+}
+
 func TestNothingIsQueuedWithoutAWebhook(t *testing.T) {
 	t.Parallel()
 
@@ -132,6 +149,18 @@ func TestNothingIsQueuedWithoutAWebhook(t *testing.T) {
 	}
 }
 
+func TestWouldSendNothingWithoutAWebhook(t *testing.T) {
+	t.Parallel()
+
+	params := newParams()
+	params.WebhookURL = nil
+	q := alerts.New(params)
+
+	if q.WouldSend(alerts.EventBan, netblock(1)) {
+		t.Error("an alert would be sent with no webhook set")
+	}
+}
+
 func TestRepeatWithinTheCooldownIsHeldBackAndCountedInTheNext(t *testing.T) {
 	t.Parallel()
 

internal/bans/bans_test.go

@@ -376,6 +376,40 @@ func TestWouldBanGivesTheBanWithoutMakingIt(t *testing.T) {
 	}
 }
 
+func TestWouldBePermanentAnswersAsTheBanWouldBeMade(t *testing.T) {
+	t.Parallel()
+
+	ledger := bans.New(defaultRules())
+	netblock := netip.MustParsePrefix("203.0.113.9/32")
+	now := midnight()
+
+	// Five bans for a limit in a row, of 1, 3, 9, 27 and 81 hours, are not
+	// permanent. The sixth, of 243 hours, would be, while a first ban for
+	// an attack would not.
+	for i := range 5 {
+		if ledger.WouldBePermanent(netblock, now, bans.CauseLimit) {
+			t.Fatalf("ban %d for a limit would be permanent", i+1)
+		}
+
+		ban, _ := ledger.BanForLimit(netblock, now, bans.Notes{})
+		now = ban.Expires
+	}
+
+	if !ledger.WouldBePermanent(netblock, now, bans.CauseLimit) {
+		t.Error("the sixth ban for a limit would not be permanent")
+	}
+
+	if ledger.WouldBePermanent(netblock, now, bans.CauseAttack) {
+		t.Error("a first ban for an attack would be permanent")
+	}
+
+	// Once a first ban for an attack has ended, the next would be permanent.
+	attack, _ := ledger.BanForAttack(netblock, now, bans.Notes{})
+	if !ledger.WouldBePermanent(netblock, attack.Expires, bans.CauseAttack) {
+		t.Error("a second ban for an attack would not be permanent")
+	}
+}
+
 func TestAttackBanDoesNotLengthenTheNextBanForALimit(t *testing.T) {
 	t.Parallel()