A ban's earlier_bans counts a ban dropped after an admin's ban (closes #128)

earlierBans took the counts in the notes of the netblock's first ban
held, so a ban dropped after an admin's ban, which came first, went
uncounted. Each ban held now gives a count, its notes' counts plus one
for it and each ban held after it, and the count that names the most
bans is taken whole. Counting from the newest ban alone would lose the
bans before an admin's ban added to bans.json without notes; taking
each cause from a different count would count twice a ban an admin
keeps, which later bans' notes count under its old cause.

Model: opus-5-5

internal/bans/admin_test.go

@@ -61,6 +61,59 @@ func TestAdminsBansAreNeverDroppedAndDoNotCountTowardMaxBans(t *testing.T) {
 	wantBans(t, ledger, map[netip.Prefix]int{adminsOnly: 2, both: 1, second: 0, third: 1})
 }
 
+func TestEarlierBansCountABanDroppedAfterAnAdminsBan(t *testing.T) {
+	t.Parallel()
+
+	rules := defaultRules()
+	rules.MaxBans = 2
+	ledger := bans.New(rules)
+	netblock := netip.MustParsePrefix("203.0.113.1/32")
+	other := netip.MustParsePrefix("203.0.113.2/32")
+
+	// An admin bans the netblock for a minute, and it then breaks a limit
+	// twice, each time after its last ban has ended.
+	ledger.BanForAdmin(netblock, midnight(), midnight().Add(time.Minute),
+		"probes for logins")
+	first, _ := ledger.BanForLimit(netblock, midnight().Add(time.Minute), bans.Notes{})
+	second, _ := ledger.BanForLimit(netblock, first.Expires, bans.Notes{})
+
+	// A ban on another netblock fills the ledger, and the netblock's first
+	// ban for a limit, its earliest that is not an admin's, goes.
+	ledger.BanForLimit(other, second.Start, bans.Notes{})
+	wantBans(t, ledger, map[netip.Prefix]int{netblock: 2, other: 1})
+
+	// The netblock's next ban still counts it.
+	third, _ := ledger.BanForLimit(netblock, second.Expires, bans.Notes{})
+	if third.Notes.EarlierBans != (bans.EarlierBans{Limit: 2, Admin: 1}) {
+		t.Errorf("the third ban for a limit has earlier bans %+v, "+
+			"want 2 for a limit and 1 an admin's", third.Notes.EarlierBans)
+	}
+}
+
+func TestEarlierBansCountABanAnAdminKeepsOnce(t *testing.T) {
+	t.Parallel()
+
+	ledger := bans.New(defaultRules())
+	netblock := netip.MustParsePrefix("203.0.113.1/32")
+
+	// The netblock breaks a limit twice, the second time after its first
+	// ban has ended, and the second ban's notes count the first. An admin
+	// then keeps the first ban.
+	first, _ := ledger.BanForLimit(netblock, midnight(), bans.Notes{})
+	second, _ := ledger.BanForLimit(netblock, first.Expires, bans.Notes{})
+
+	kept := first
+	kept.Cause = bans.CauseAdmin
+	ledger.LoadEdit([]bans.Ban{kept, second})
+
+	// The netblock's next ban counts the kept ban once, as an admin's.
+	third, _ := ledger.BanForLimit(netblock, second.Expires, bans.Notes{})
+	if third.Notes.EarlierBans != (bans.EarlierBans{Limit: 1, Admin: 1}) {
+		t.Errorf("the third ban for a limit has earlier bans %+v, "+
+			"want 1 for a limit and 1 an admin's", third.Notes.EarlierBans)
+	}
+}
+
 func TestReasonOfTheBansSmallwebwafMakes(t *testing.T) {
 	t.Parallel()
 

internal/bans/bans.go

@@ -687,26 +687,51 @@ func (l *Ledger) ban(
 }
 
 // earlierBans returns how many bans a netblock with the bans held, oldest
-// first, has had, by cause: the first ban held counts the bans the
-// netblock had before that one, since dropped to make room, and each ban
-// held adds one.
+// first, has had, by cause. Each ban held gives a count: the bans its
+// notes count before it, and one for it and each ban held after it. A
+// ban's count misses a ban dropped after it to make room, and that of an
+// admin's ban added to bans.json without notes misses the bans before it,
+// so the count that names the most bans is taken, whole: a ban an admin
+// keeps by giving it CauseAdmin is still counted under its old cause in
+// later bans' notes, and taking each cause from another count would count
+// it twice.
 func earlierBans(held []Ban) EarlierBans {
-	earlier := held[0].Notes.EarlierBans
+	// fromHere counts ban and the bans held after it.
+	var most, fromHere EarlierBans
 
-	for _, ban := range held {
+	for _, ban := range slices.Backward(held) {
 		switch ban.Cause {
 		case CauseLimit:
-			earlier.Limit++
+			fromHere.Limit++
 		case CauseAttack:
-			earlier.Attack++
+			fromHere.Attack++
 		case CauseAdmin:
-			earlier.Admin++
+			fromHere.Admin++
 		case CauseCrowdSec:
-			earlier.CrowdSec++
+			fromHere.CrowdSec++
+		}
+
+		notes := ban.Notes.EarlierBans
+		count := EarlierBans{
+			Limit:    notes.Limit + fromHere.Limit,
+			Attack:   notes.Attack + fromHere.Attack,
+			Admin:    notes.Admin + fromHere.Admin,
+			CrowdSec: notes.CrowdSec + fromHere.CrowdSec,
+		}
+
+		// Of counts that name as many bans, the earlier ban's is taken: it
+		// counts more of the bans held by the cause they have now.
+		if count.total() >= most.total() {
+			most = count
 		}
 	}
 
-	return earlier
+	return most
+}
+
+// total returns how many bans e counts, of all causes.
+func (e EarlierBans) total() int {
+	return e.Limit + e.Attack + e.Admin + e.CrowdSec
 }
 
 // markChanged has Changed receive a value, unless one is waiting already.

internal/proxy/request.go

@@ -795,9 +795,19 @@ func (rq *request) responseTimedOut() {
 	}
 }
 
-// responseReceived is called once the app has sent its whole answer.
+// responseReceived is called once the app has sent its whole answer. An
+// app may answer before the client has sent its whole body, as with a 404
+// it sends without reading it. The timeouts then run on: until the
+// transport's read of the body returns, Go's server cannot send the
+// answer, and SWWAF_CLIENT_REQUEST_TIMEOUT is what ends that read for a
+// client that stops sending.
 func (rq *request) responseReceived() {
 	rq.complete = true
+
+	if rq.body != nil && !rq.body.received.Load() {
+		return
+	}
+
 	rq.stopTimers()
 }
 

internal/proxy/timeouts_test.go

@@ -194,6 +194,60 @@ func sendLargeBody(t *testing.T, addr string) net.Conn {
 	return conn
 }
 
+func TestClientStopsSendingAfterTheAppHasAnswered(t *testing.T) {
+	t.Parallel()
+
+	// answeredAt is when the app answered, or nil if the bytes the client
+	// sent never reached it.
+	var answeredAt atomic.Pointer[time.Time]
+
+	// The app answers without reading the whole body, as an app does for
+	// a path it does not serve, and only once smallwebwaf waits for the
+	// rest of it: the app takes the bytes the client sent, and then waits
+	// half the timeout, far longer than smallwebwaf takes to go on to
+	// wait.
+	app := startApp(t, func(w http.ResponseWriter, r *http.Request) {
+		_, err := io.ReadFull(r.Body, make([]byte, len("the first bytes")))
+		if err != nil {
+			return
+		}
+
+		time.Sleep(shortTimeout / 2)
+		answeredAt.Store(new(time.Now()))
+		http.NotFound(w, r)
+	})
+	addr, out := startProxy(t, app.URL, map[string]string{
+		clientRequestTimeout: shortTimeoutSetting,
+		metricsToken:         token,
+	})
+
+	start := time.Now()
+	got := readResponse(t, sendPartOfBody(t, addr))
+	wantTimedOut(t, start)
+
+	// Close returns once the app has finished with the request.
+	app.Close()
+
+	// The app's answer came before the time ran out, so the client is
+	// sent that answer, not smallwebwaf's 408. Only a hold-up of the test
+	// process can make it come later, and SPEC.md then asks for 408, as
+	// smallwebwaf was waiting for the client, or for 504 if the bytes the
+	// client sent had not reached the app.
+	at := answeredAt.Load()
+	want := http.StatusNotFound
+
+	switch {
+	case at == nil:
+		want = http.StatusGatewayTimeout
+	case at.Sub(start) >= shortTimeout:
+		want = http.StatusRequestTimeout
+	}
+
+	wantStatus(t, got, want)
+	wantLine(t, out.requestLine(t), want, requestlog.ActionTimedOut)
+	wantLimitHits(t, addr, clientRequestTimeout, 1)
+}
+
 func TestAppTooSlowToAnswer(t *testing.T) {
 	t.Parallel()