Render templates via a buffer, not the ResponseWriter (closes #123)

executeTemplate ran the template straight into the ResponseWriter, so a
mid-render failure left the already-emitted prefix written and the
response committed: the handler could no longer set a 500 and the
client got a truncated page, typically with a 200. It also let handler
tests pass against the flushed prefix of a page that aborted below the
assertions.

Execute into a bytes.Buffer instead, and set the content type and copy
the buffer out only once rendering has fully succeeded. On failure
nothing has been written, so the 500 still reaches the client.

Add a test that renders a template failing partway through and asserts
both the 500 and that the body carries no part of the aborted page.
Against the previous streaming renderer it fails on both counts (200,
body "PARTIAL PAGE CONTENTInternal server error").

README.md

@@ -93,9 +93,8 @@ TTY detection, and security headers are always applied.
 | `METRICS_USERNAME`      | Basic auth username for `/metrics`  | `""`     |
 | `METRICS_PASSWORD`      | Basic auth password for `/metrics`  | `""`     |
 | `SENTRY_DSN`            | Sentry error reporting DSN          | `""`     |
-| `RETENTION_SWEEP_INTERVAL` | Retention reaper period (Go duration, must be positive) | `1h` |
 | `SESSION_IDLE_TIMEOUT`  | Idle session timeout (Go duration)  | `24h`    |
-| `RECEIVER_RATE_LIMIT`   | Receiver requests/minute per IP per entrypoint (10x that per IP across the route) | `120` |
+| `RECEIVER_RATE_LIMIT`   | Receiver requests/minute per IP per entrypoint | `120` |
 | `TRUSTED_PROXIES`       | CIDRs whose forwarded headers are trusted | `""` (none) |
 
 #### Trusted proxies
@@ -174,12 +173,8 @@ its value and refuses to start, rather than silently running with a
 substituted default. `PORT=eighty`, `DEBUG=ture`, and
 `RETENTION_SWEEP_INTERVAL=1 hour` all abort startup. `PORT` must
 additionally be a number in the range 1–65535,
-`RECEIVER_RATE_LIMIT` must be at least 1,
+`RECEIVER_RATE_LIMIT` must be at least 1, and every entry in
-`RETENTION_SWEEP_INTERVAL` must be greater than zero (it is a ticker
+`TRUSTED_PROXIES` must be a CIDR block or a bare IP address.
-period, so `0s` or a negative value would crash the reaper after
-startup), and every entry in `TRUSTED_PROXIES` must be a CIDR block or
-a bare IP address. `SESSION_IDLE_TIMEOUT` is the exception: a
-non-positive value there means idle expiry is disabled, not invalid.
 
 Boolean variables (`DEBUG`, `MAINTENANCE_MODE`) accept exactly the
 spellings Go's `strconv.ParseBool` accepts — `1`, `t`, `T`, `TRUE`,
@@ -856,26 +851,6 @@ legitimate webhook senders). Requests over the limit receive HTTP 429
 with a `Retry-After` header. A set-but-invalid `RECEIVER_RATE_LIMIT`
 value aborts startup rather than silently falling back to the default.
 
-A second limit sits in front of that one, keyed on the client IP alone
-and covering the whole route at ten times `RECEIVER_RATE_LIMIT` requests
-per minute (default 1200). The per-entrypoint limit needs it: the route
-pattern matches any single path segment, so a client that invents a
-fresh path per request gets a fresh per-entrypoint bucket every time and
-would otherwise have no aggregate limit at all — while each of those
-requests still costs an entrypoint lookup before it 404s. The aggregate
-limit leaves room for one address to drive several entrypoints at their
-full rate, and it is not configurable separately.
-
-What that aggregate limit bounds is the database work an invented path
-costs, not the number of log lines it produces. The path is
-attacker-controlled, so nothing on this route writes it to the log
-above `DEBUG`: a path that names no entrypoint is recorded by the
-handler at `DEBUG`, and the aggregate limiter logs its rejections at
-`DEBUG` and without the path. Every request is still recorded once by
-the access log, at `INFO`, with its full URL, whether it was served or
-rejected — so a flood of invented paths still writes one `INFO` line
-per request.
-
 Every limiter here — receiver, login, and password change — identifies
 the client the same way, through one shared key function: the
 connection's own address, unless the peer is listed in
@@ -884,14 +859,7 @@ instead. See [Trusted proxies](#trusted-proxies). Deployed without that
 variable set, a client behind a reverse proxy shares one bucket with
 every other client behind the same proxy, which is the safe direction
 to be wrong in: set `TRUSTED_PROXIES` to the proxy's address to get
-per-client limits back. That shared bucket matters more for the
+per-client limits back.
-aggregate limit than for the per-entrypoint one: with `TRUSTED_PROXIES`
-unset behind the reverse proxy a production deployment is required to
-run behind, every request keys on the proxy, so the aggregate limit
-becomes a service-wide ceiling of 1200 requests per minute across all
-senders and all entrypoints, where the per-entrypoint limit's capacity
-still grows with the number of entrypoints. Any deployment with more
-than a handful of busy entrypoints must set `TRUSTED_PROXIES`.
 
 Finer-grained per-webhook rate limits (configured in the web UI and
 enforced in the webhook handler) can layer on top of this env-level

TODO.md

@@ -1,62 +1,31 @@
 # Workflow
 
-One issue per unit of work, one branch and one PR per issue:
+* branch (from `main`)
-
+* do the work in Next Step
-* ensure a tracked issue exists with a definition of done
+* move Next Step to the top of Completed Steps
-* branch from `next` (never from `main`)
+* move the top item of Future Steps into Next Step
-* do the work; open a PR based on `next` (never on `main`)
+* commit (`TODO.md` changes in the same commit as the work)
-* pass an independent review, then the manager squash-merges into `next`
+* merge to `main` if the branch is not protected, otherwise open a PR
-* push; nothing stays local-only
+* push
-
-`next` is the branch for the next milestone and must stay green and
-mergeable to `main` without notice. One `next` -> `main` PR accumulates
-the milestone; releases are cut from `main` separately.
-
-Issue branches do NOT touch this file — the manager maintains it on
-`next`. Every branch editing `TODO.md` conflicts with every other
-(#112).
 
 # Status
 
-pre-1.0. No git tags exist. `main` (4f5ecb1) is a working webhook proxy
+pre-1.0. No git tags exist. main (4f5ecb1) is a working webhook proxy
 with auth, CSRF/SSRF protections, login rate limiting, Slack target,
 event retention (#63), the database archiving target (#43), the admin
 password change flow (#65), policy compliance (#6), pinned lint tooling
-(#55), and fail-loud configuration parsing (#80).
+(#55), and fail-loud configuration parsing (#80). Note: TODO.md was
-
+deliberately deleted from this repo in f9a9569 (2026-03-01, #6); its
-`next` (9bfd033) holds the completed 1.0.0 milestone: every issue in it
+content was folded into the README TODO section, which this draft
-is closed, and it is verified green by cache-defeated container runs
+reconstructs as of 2026-07-06.
-rather than by the CI badge, which can pass without executing anything
-(#119). Note: TODO.md was deliberately deleted from this repo in f9a9569
-(2026-03-01, #6); its content was folded into the README TODO section,
-which this draft reconstructs as of 2026-07-06.
 
 # Next Step
 
-Tag 1.0.0 from `main` once the milestone PR merges, then repair the CI
+Manual event redelivery from the web UI (replay is a core promised
-gate (#119) before the next cycle's work lands — a gate that can report
+capability in the README rationale).
-success without running is the one thing every other guarantee here
-rests on.
 
 # Completed Steps
 
-- 2026-08-12 Bound the `X-Forwarded-For` scan's allocation to the hop
-  cap: the reverse walk cuts entries with `strings.LastIndexByte`
-  instead of joining and splitting, so a 1 MB header allocates 16 bytes
-  rather than 1.6 MB per request on the unauthenticated receiver.
-  Semantics proven unchanged by differential testing against the
-  previous implementation (#133)
-- 2026-08-12 Cap the `X-Forwarded-For` hop walk at 64 entries, so an
-  attacker-supplied chain cannot burn unbounded CPU in the rate-limit
-  key function; running off the end falls back to the peer address
-  (#124)
-- 2026-08-12 Gate forwarded-header trust behind a `TRUSTED_PROXIES` CIDR
-  list: all three rate limiters key on the connection's own address
-  unless the direct peer is a configured proxy, in which case
-  `X-Forwarded-For` is walked right to left for the first non-proxy hop.
-  Default trusts nothing, and a set-but-unparseable value aborts
-  startup. Before this, any client could mint a fresh bucket or drain
-  another's by rotating a spoofed header (#88)
 - 2026-08-11 Web UI cleanup: nav terminology unified on Webhooks, the
   Profile settings placeholder removed, a progressive-enhancement copy
   button for the entrypoint URL, and retention form copy that states the

internal/config/config.go

@@ -92,7 +92,6 @@ type Config struct {
 	SentryDSN       string
 
 	// RetentionSweepInterval is how often the retention reaper runs.
-	// Always positive: it becomes a time.NewTicker period.
 	RetentionSweepInterval time.Duration
 
 	// SessionIdleTimeout is the sliding inactivity window after
@@ -236,34 +235,6 @@ func envDuration(
 	return d, nil
 }
 
-// envPositiveDuration returns the value of the named environment
-// variable parsed as a Go duration that must be greater than zero.
-// Returns defaultValue if not set. A set value that is unparseable or
-// non-positive is a hard error naming the key and the bad value.
-//
-// This is for durations that reach time.NewTicker, which panics on a
-// non-positive period, in a goroutine started after startup has
-// already reported success. It is deliberately not used for durations
-// where non-positive means "disabled" (SESSION_IDLE_TIMEOUT).
-func envPositiveDuration(
-	key string,
-	defaultValue time.Duration,
-) (time.Duration, error) {
-	d, err := envDuration(key, defaultValue)
-	if err != nil {
-		return 0, err
-	}
-
-	if d <= 0 {
-		return 0, fmt.Errorf(
-			"%w: %s must be greater than zero, got %s",
-			ErrNonPositiveValue, key, d,
-		)
-	}
-
-	return d, nil
-}
-
 // parseCIDR parses one trusted-proxy list entry, which may be a
 // CIDR block ("10.0.0.0/8") or a bare address ("10.0.0.1", treated
 // as a single-host block).
@@ -375,7 +346,7 @@ func loadFromEnv() (*Config, error) {
 		return nil, err
 	}
 
-	retentionSweepInterval, err := envPositiveDuration(
+	retentionSweepInterval, err := envDuration(
 		"RETENTION_SWEEP_INTERVAL",
 		defaultRetentionSweepInterval,
 	)
@@ -383,8 +354,6 @@ func loadFromEnv() (*Config, error) {
 		return nil, err
 	}
 
-	// Non-positive is "disabled" here, not invalid, so this stays on
-	// envDuration.
 	sessionIdleTimeout, err := envDuration(
 		"SESSION_IDLE_TIMEOUT",
 		defaultSessionIdleTimeout,

internal/config/config_test.go

@@ -139,11 +139,7 @@ func TestRetentionSweepInterval(t *testing.T) {
 		set         bool
 		value       string
 		expectError bool
-		// sentinel, when set, must be wrapped by the startup
+		expected    time.Duration
-		// error; every error case must additionally name the
-		// variable in its message.
-		sentinel error
-		expected time.Duration
 	}{
 		{
 			name:     caseUnsetUsesDefault,
@@ -162,24 +158,6 @@ func TestRetentionSweepInterval(t *testing.T) {
 			value:       "not-a-duration",
 			expectError: true,
 		},
-		{
-			// A non-positive period panics the ticker in the
-			// reaper and archive-sweeper goroutines, long after
-			// startup has reported success, so it has to fail
-			// here instead.
-			name:        "zero fails startup",
-			set:         true,
-			value:       "0s",
-			expectError: true,
-			sentinel:    config.ErrNonPositiveValue,
-		},
-		{
-			name:        "negative fails startup",
-			set:         true,
-			value:       "-1h",
-			expectError: true,
-			sentinel:    config.ErrNonPositiveValue,
-		},
 	}
 
 	for _, tt := range tests {
@@ -197,9 +175,7 @@ func TestRetentionSweepInterval(t *testing.T) {
 			}
 
 			if tt.expectError {
-				expectStartupErrorFor(
+				expectStartupError(t)
-					t, "RETENTION_SWEEP_INTERVAL", tt.sentinel,
-				)
 			} else {
 				testRetentionSweepIntervalSuccess(t, tt.expected)
 			}
@@ -305,22 +281,6 @@ func TestSessionIdleTimeout(t *testing.T) {
 			value:       "not-a-duration",
 			expectError: true,
 		},
-		{
-			// Non-positive is "idle expiry disabled" for this
-			// variable, not a configuration error: unlike
-			// RETENTION_SWEEP_INTERVAL it never becomes a ticker
-			// period.
-			name:     "zero disables idle expiry",
-			set:      true,
-			value:    "0s",
-			expected: 0,
-		},
-		{
-			name:     "negative disables idle expiry",
-			set:      true,
-			value:    "-1h",
-			expected: -time.Hour,
-		},
 	}
 
 	for _, tt := range tests {

internal/handlers/export_test.go

@@ -1,6 +1,19 @@
 package handlers
 
-import "net/http"
+import (
+	"html/template"
+	"net/http"
+)
+
+// AddTemplateForTest registers a template under a page name so that
+// the handlers_test package can drive the render path with a
+// template of its own.
+func (s *Handlers) AddTemplateForTest(
+	pageTemplate string,
+	tmpl *template.Template,
+) {
+	s.templates[pageTemplate] = tmpl
+}
 
 // RenderTemplateForTest exposes renderTemplate for use in the
 // handlers_test package.

internal/handlers/handlers.go

@@ -3,6 +3,7 @@
 package handlers
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
@@ -224,13 +225,20 @@ func (s *Handlers) renderTemplate(
 	s.executeTemplate(w, tmpl, wrapper)
 }
 
-// executeTemplate runs the template and handles errors.
+// executeTemplate renders the template into a buffer and writes to
+// the response only once rendering has fully succeeded. Executing
+// straight into the ResponseWriter commits a partial body and a 200
+// status before a mid-render error can be reported, leaving no way
+// to serve a 500. These pages are small, so holding one in memory is
+// the right trade.
 func (s *Handlers) executeTemplate(
 	w http.ResponseWriter,
 	tmpl *template.Template,
 	data any,
 ) {
-	err := tmpl.Execute(w, data)
+	var buf bytes.Buffer
+
+	err := tmpl.Execute(&buf, data)
 	if err != nil {
 		s.log.Error(
 			"failed to execute template", "error", err,
@@ -239,5 +247,16 @@ func (s *Handlers) executeTemplate(
 			w, "Internal server error",
 			http.StatusInternalServerError,
 		)
+
+		return
+	}
+
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+
+	_, err = buf.WriteTo(w)
+	if err != nil {
+		s.log.Error(
+			"failed to write rendered page", "error", err,
+		)
 	}
 }

internal/handlers/handlers_test.go

@@ -2,6 +2,8 @@ package handlers_test
 
 import (
 	"context"
+	"errors"
+	"html/template"
 	"net/http"
 	"net/http/httptest"
 	"sync"
@@ -220,6 +222,68 @@ func TestRenderTemplate(t *testing.T) {
 	)
 }
 
+// errMidRender is the failure a test template raises partway through
+// rendering.
+var errMidRender = errors.New("deliberate mid-render failure")
+
+// midRenderFailure is template data whose first method renders and
+// whose second fails, so the template aborts after output has
+// already been produced.
+type midRenderFailure struct{}
+
+// Prefix is the output a streaming renderer would flush before the
+// failure below aborts the template.
+func (midRenderFailure) Prefix() string { return partialPageMarker }
+
+// Boom aborts template execution.
+func (midRenderFailure) Boom() (string, error) {
+	return "", errMidRender
+}
+
+// partialPageMarker is content the failing template emits before it
+// aborts.
+const partialPageMarker = "PARTIAL PAGE CONTENT"
+
+// TestRenderTemplateMidRenderErrorSendsNoPartialBody proves the
+// renderer does not commit output it cannot finish: a template that
+// fails partway through must yield a 500 and a body carrying none of
+// the content emitted before the failure. Against a renderer that
+// executes straight into the ResponseWriter this fails on both
+// counts, returning 200 with the prefix already flushed.
+func TestRenderTemplateMidRenderErrorSendsNoPartialBody(t *testing.T) {
+	t.Parallel()
+
+	var h *handlers.Handlers
+
+	app := newTestApp(t, &h)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	h.AddTemplateForTest("failing.html", template.Must(
+		template.New("failing").Parse(
+			`{{.Data.Prefix}}{{.Data.Boom}}TAIL`,
+		),
+	))
+
+	req := httptest.NewRequestWithContext(
+		context.Background(), http.MethodGet, "/", nil)
+	w := httptest.NewRecorder()
+
+	h.RenderTemplateForTest(
+		w, req, "failing.html", midRenderFailure{},
+	)
+
+	assert.Equal(
+		t, http.StatusInternalServerError, w.Code,
+		"a failed render must report a 500",
+	)
+	assert.Equal(
+		t, "Internal server error\n", w.Body.String(),
+		"the response must carry no part of the aborted page",
+	)
+}
+
 func TestBuildDatabaseTargetConfig_Valid(t *testing.T) {
 	t.Parallel()
 

internal/handlers/webhook.go

@@ -39,6 +39,12 @@ func (h *Handlers) HandleWebhook() http.HandlerFunc {
 			return
 		}
 
+		h.log.Info("webhook request received",
+			"entrypoint_uuid", entrypointUUID,
+			"method", r.Method,
+			"remote_addr", r.RemoteAddr,
+		)
+
 		entrypoint, ok := h.lookupEntrypoint(
 			w, r, entrypointUUID,
 		)
@@ -46,18 +52,6 @@ func (h *Handlers) HandleWebhook() http.HandlerFunc {
 			return
 		}
 
-		// Logged only once the UUID is known to name a real
-		// entrypoint. The UUID comes straight out of the path on
-		// the one unauthenticated endpoint, so logging it before
-		// the lookup let a client write an INFO line per invented
-		// path; the request itself is already in the access log
-		// and a miss is already logged at DEBUG.
-		h.log.Info("webhook request received",
-			"entrypoint_uuid", entrypointUUID,
-			"method", r.Method,
-			"remote_addr", r.RemoteAddr,
-		)
-
 		if !entrypoint.Active {
 			http.Error(w, "Gone", http.StatusGone)
 

internal/middleware/export_test.go

@@ -25,11 +25,6 @@ func IPFromHostPort(hp string) string {
 	return ipFromHostPort(hp)
 }
 
-// ClientKeyForTest exposes clientKey for testing.
-func ClientKeyForTest(m *Middleware, r *http.Request) string {
-	return m.clientKey(r)
-}
-
 // IsClientTLS exposes isClientTLS for testing.
 func IsClientTLS(r *http.Request) bool {
 	return isClientTLS(r)
@@ -41,13 +36,3 @@ const LoginRateLimitConst = loginRateLimit
 // PasswordChangeRateLimitConst exposes the
 // passwordChangeRateLimit constant.
 const PasswordChangeRateLimitConst = passwordChangeRateLimit
-
-// ReceiverAggregateMultiplierConst exposes the
-// receiverAggregateMultiplier constant.
-const ReceiverAggregateMultiplierConst = receiverAggregateMultiplier
-
-// ReceiverAggregateLimitForTest exposes receiverAggregateLimit for
-// testing.
-func ReceiverAggregateLimitForTest(perEntrypoint int) int {
-	return receiverAggregateLimit(perEntrypoint)
-}

internal/middleware/ratelimit.go

@@ -1,7 +1,6 @@
 package middleware
 
 import (
-	"math"
 	"net/http"
 	"net/netip"
 	"slices"
@@ -33,21 +32,6 @@ const (
 	// receiver rate limit. The configured limit is expressed in
 	// requests per minute.
 	receiverRateInterval = 1 * time.Minute
-
-	// receiverAggregateMultiplier scales the configured
-	// per-entrypoint receiver limit into the aggregate limit one
-	// client IP may spend across the whole /webhook/* route. Ten
-	// entrypoints' worth lets a single sender address drive several
-	// entrypoints at their full rate, while still capping what one
-	// address costs the unauthenticated receiver.
-	receiverAggregateMultiplier = 10
-
-	// maxForwardedHops bounds how many X-Forwarded-For entries the
-	// chain walk examines. Real chains are one to three hops, but a
-	// client can pad the header up to MaxHeaderBytes, so without a
-	// bound every request pays a walk proportional to whatever the
-	// client sent.
-	maxForwardedHops = 64
 )
 
 // normalizeAddr strips the IPv4-in-IPv6 wrapper and any zone from
@@ -86,49 +70,26 @@ func (m *Middleware) isTrustedProxy(addr netip.Addr) bool {
 // a trusted proxy is the client. A hop that cannot be read as a bare
 // address ends the walk: past it the chain is not the shape assumed
 // here, so the caller falls back to the peer address.
-//
-// Only the last maxForwardedHops entries are examined. A longer chain
-// is padding, and running out of hops falls back to the peer address
-// the same way an unreadable hop does.
-//
-// The entries are cut off the right end of each header value in place
-// rather than split out of it: the receiver is unauthenticated and a
-// client can pad the header up to MaxHeaderBytes, so splitting would
-// allocate in proportion to the padding (about 8 MB for a 1 MB
-// header) before the cap could discard any of it. Multiple header
-// values are walked in reverse for the same reason, since joining
-// them copies the whole chain.
 func (m *Middleware) forwardedClientAddr(
 	r *http.Request,
 ) (netip.Addr, bool) {
-	seen := 0
+	hops := strings.Split(
+		strings.Join(r.Header.Values("X-Forwarded-For"), ","), ",",
+	)
 
-	for _, value := range slices.Backward(
+	for _, hop := range slices.Backward(hops) {
-		r.Header.Values("X-Forwarded-For"),
+		hop = strings.TrimSpace(hop)
-	) {
+		if hop == "" {
-		for last := false; !last && seen < maxForwardedHops; seen++ {
+			continue
-			hop := value
+		}
 
-			comma := strings.LastIndexByte(value, ',')
+		addr, err := netip.ParseAddr(hop)
-			if comma < 0 {
+		if err != nil {
-				last = true
+			return netip.Addr{}, false
-			} else {
+		}
-				hop, value = value[comma+1:], value[:comma]
-			}
 
-			hop = strings.TrimSpace(hop)
+		if addr = normalizeAddr(addr); !m.isTrustedProxy(addr) {
-			if hop == "" {
+			return addr, true
-				continue
-			}
-
-			addr, err := netip.ParseAddr(hop)
-			if err != nil {
-				return netip.Addr{}, false
-			}
-
-			if addr = normalizeAddr(addr); !m.isTrustedProxy(addr) {
-				return addr, true
-			}
 		}
 	}
 
@@ -152,10 +113,8 @@ func (m *Middleware) clientKey(r *http.Request) string {
 	peer, err := netip.ParseAddr(ipFromHostPort(r.RemoteAddr))
 	if err != nil {
 		// Not an address we can reason about; key on the raw
-		// value, the most specific identity left. On a
+		// value rather than collapsing such peers into one
-		// Unix-socket listener every peer carries the same
+		// shared bucket.
-		// RemoteAddr and so shares one bucket, which is the
-		// fail-closed direction.
 		return r.RemoteAddr
 	}
 
@@ -183,31 +142,6 @@ func (m *Middleware) tooManyRequests(
 	}
 }
 
-// floodTooManyRequests returns the 429 handler for a limiter whose
-// rejections are themselves the flood: it logs at DEBUG and without
-// the path, then answers with responseMessage.
-//
-// The aggregate receiver limiter trips exactly when one address is
-// sending faster than the receiver wants to serve, so its rejection
-// log is one line per request of that flood. At WARN with "path" that
-// hands a client a way to write its own text into the operator's log,
-// at a level that trips alerting, once per request — the log-volume
-// problem this limiter exists to bound. DEBUG is off in production by
-// default, so a flood costs nothing here; the path is dropped so that
-// turning DEBUG on to diagnose one does not restore the problem.
-//
-// This limiter bounds the database work an invented path costs, not
-// the number of log lines it produces: the access log in
-// middleware.go still records every request, served or rejected.
-func (m *Middleware) floodTooManyRequests(
-	logMessage, responseMessage string,
-) http.HandlerFunc {
-	return func(w http.ResponseWriter, _ *http.Request) {
-		m.log.Debug(logMessage)
-		http.Error(w, responseMessage, http.StatusTooManyRequests)
-	}
-}
-
 // LoginRateLimit returns middleware that enforces per-IP rate
 // limiting on login attempts using go-chi/httprate. Only POST
 // requests are rate-limited; GET requests (rendering the login
@@ -276,26 +210,15 @@ func (m *Middleware) postRateLimit(
 	}
 }
 
-// ReceiverRateLimit returns middleware that rate-limits the public
+// ReceiverRateLimit returns middleware that rate-limits the
-// webhook receiver endpoint with two limits in series.
+// public webhook receiver endpoint per client IP per request
-//
+// path (the path contains the entrypoint UUID, so each sender
-// The inner limit is per client IP per request path: the path
+// is limited per entrypoint without affecting other senders or
-// contains the entrypoint UUID, so each sender is limited per
+// other entrypoints). The limit is Config.ReceiverRateLimit
-// entrypoint without affecting other senders or other entrypoints.
+// requests per minute. Requests over the limit receive a 429.
-// It is Config.ReceiverRateLimit requests per minute.
+// Clients are identified by rateLimitKey.
-//
-// That limit alone bounds nothing in aggregate. The route pattern
-// /webhook/{uuid} matches any single segment, so a client that
-// invents a fresh path per request mints a fresh bucket per request
-// and never refills one — and every such request still reaches the
-// handler's entrypoint lookup before it 404s. The outer limit is
-// therefore keyed on the client IP alone, capping what one address
-// can spend across the whole route however it varies the path.
-//
-// Requests over either limit receive a 429. Clients are identified
-// by rateLimitKey.
 func (m *Middleware) ReceiverRateLimit() func(http.Handler) http.Handler {
-	perEntrypoint := httprate.Limit(
+	return httprate.Limit(
 		m.params.Config.ReceiverRateLimit,
 		receiverRateInterval,
 		httprate.WithKeyFuncs(
@@ -307,31 +230,4 @@ func (m *Middleware) ReceiverRateLimit() func(http.Handler) http.Handler {
 			"Too many requests. Please slow down.",
 		)),
 	)
-
-	aggregate := httprate.Limit(
-		receiverAggregateLimit(m.params.Config.ReceiverRateLimit),
-		receiverRateInterval,
-		httprate.WithKeyFuncs(m.rateLimitKey),
-		httprate.WithLimitHandler(m.floodTooManyRequests(
-			"webhook receiver aggregate rate limit exceeded",
-			"Too many requests. Please slow down.",
-		)),
-	)
-
-	return func(next http.Handler) http.Handler {
-		return aggregate(perEntrypoint(next))
-	}
-}
-
-// receiverAggregateLimit is the per-IP aggregate limit derived from
-// the configured per-entrypoint limit. The operator sets the latter
-// and nothing bounds it from above, so the multiplication is
-// saturated rather than allowed to wrap into a negative limit that
-// would reject every request.
-func receiverAggregateLimit(perEntrypoint int) int {
-	if perEntrypoint > math.MaxInt/receiverAggregateMultiplier {
-		return math.MaxInt
-	}
-
-	return perEntrypoint * receiverAggregateMultiplier
 }

internal/middleware/ratelimit_test.go

@@ -4,15 +4,11 @@ import (
 	"context"
 	"fmt"
 	"log/slog"
-	"math"
 	"net/http"
 	"net/http/httptest"
 	"net/netip"
 	"os"
-	"runtime"
-	"strings"
 	"testing"
-	"time"
 
 	"github.com/stretchr/testify/assert"
 	"sneak.berlin/go/webhooker/internal/config"
@@ -572,228 +568,6 @@ func TestRateLimitKey_ChainWalkSkipsClientPrepended(t *testing.T) {
 	)
 }
 
-// TestRateLimitKey_LongChainCapsWalkAndFallsBackToPeer covers the
-// hop-walk cap. A client behind the trusted proxy can pad
-// X-Forwarded-For with tens of thousands of trusted-looking hops,
-// which costs a walk proportional to the padding and, once the walk
-// runs off the left end of the chain, reaches the entry the client
-// put there. Capping the walk stops both: the key falls back to the
-// peer address, so rotating the head of the chain mints no bucket,
-// and the run does not scale with the chain length.
-func TestRateLimitKey_LongChainCapsWalkAndFallsBackToPeer(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	// 50k hops is roughly 0.9 MB, within the default
-	// MaxHeaderBytes.
-	const hops = 50000
-
-	padding := strings.Repeat(", 10.0.0.2", hops-1)
-
-	start := time.Now()
-
-	assertSharedBucket(
-		t, trustedProxies("10.0.0.0/8"), "10.0.0.1:44444",
-		func(i int) map[string]string {
-			return map[string]string{
-				headerXFF: fmt.Sprintf("9.9.9.%d%s", i+1, padding),
-			}
-		},
-		"a padded X-Forwarded-For chain must fall back to the "+
-			"peer address, not reach the client-controlled entry "+
-			"at the head of the chain",
-	)
-
-	assert.Less(
-		t, time.Since(start), 2*time.Second,
-		"the capped walk must not scale with the chain length",
-	)
-}
-
-// TestRateLimitKey_LongChainAllocationIsBounded is the allocation
-// half of the hop cap. Capping the walk still left every request
-// paying for the whole header the client sent, because the chain was
-// split before it was capped: about 8 MB of []string for the 1 MB a
-// default MaxHeaderBytes allows, on the unauthenticated receiver.
-//
-// Bytes are the measurement, not allocation count: strings.Split of a
-// 1 MB chain is a single allocation, so testing.AllocsPerRun scores
-// it as cheap. The test is deliberately sequential — it reads
-// process-wide counters, and Go runs this package's parallel tests
-// only after the sequential ones finish.
-//
-//nolint:paralleltest // reads process-wide allocation counters
-func TestRateLimitKey_LongChainAllocationIsBounded(t *testing.T) {
-	// 100k hops of ", 10.0.0.2" is roughly 1 MB.
-	const (
-		hops            = 100000
-		iterations      = 50
-		maxBytesPerCall = 4096
-	)
-
-	m := rateLimitMiddleware(t, &config.Config{
-		TrustedProxies: trustedProxies("10.0.0.0/8"),
-	})
-
-	req := httptest.NewRequestWithContext(
-		context.Background(), http.MethodPost, loginPath, nil,
-	)
-	req.RemoteAddr = "10.0.0.1:44444"
-	req.Header.Set(
-		headerXFF, "9.9.9.9"+strings.Repeat(", 10.0.0.2", hops),
-	)
-
-	var before, after runtime.MemStats
-
-	var key string
-
-	runtime.ReadMemStats(&before)
-
-	for range iterations {
-		key = middleware.ClientKeyForTest(m, req)
-	}
-
-	runtime.ReadMemStats(&after)
-
-	perCall := (after.TotalAlloc - before.TotalAlloc) / iterations
-
-	assert.Less(
-		t, perCall, uint64(maxBytesPerCall),
-		"a %d-byte X-Forwarded-For must not allocate in proportion "+
-			"to its length, but cost %d bytes per call",
-		len(req.Header.Get(headerXFF)), perCall,
-	)
-
-	assert.Equal(
-		t, "10.0.0.1", key,
-		"the padded chain must still fall back to the peer address",
-	)
-}
-
-// TestReceiverRateLimit_LimitsAggregateAcrossInventedPaths is the
-// regression test for the per-path bucket key. The route pattern
-// matches any single segment, so a client that never reuses a path
-// never reuses a per-entrypoint bucket either, and its aggregate
-// rate against the receiver is whatever it likes — with every
-// request reaching an entrypoint lookup before it 404s. The IP-only
-// aggregate limiter is what bounds that, so this must fail if the
-// aggregate limiter is removed.
-func TestReceiverRateLimit_LimitsAggregateAcrossInventedPaths(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	const (
-		limit = 3
-		ip    = "6.6.6.6:1234"
-	)
-
-	aggregate := limit * middleware.ReceiverAggregateMultiplierConst
-
-	handler := receiverLimitedHandler(t, limit)
-
-	// Every request goes to a path this client has never used, so
-	// none of them shares a per-entrypoint bucket with another.
-	for i := range aggregate {
-		w := receiverPost(
-			handler, ip, fmt.Sprintf("/webhook/invented-%d", i),
-		)
-		assert.Equal(
-			t, http.StatusOK, w.Code,
-			"request %d to a distinct path should pass", i,
-		)
-	}
-
-	w := receiverPost(
-		handler, ip, fmt.Sprintf("/webhook/invented-%d", aggregate),
-	)
-	assert.Equal(
-		t, http.StatusTooManyRequests, w.Code,
-		"a client must not be able to raise its aggregate rate "+
-			"against /webhook/* by varying the path",
-	)
-
-	// The aggregate limit is still per client IP: exhausting one
-	// address must not throttle another.
-	w = receiverPost(handler, "6.6.6.7:1234", "/webhook/invented-0")
-	assert.Equal(
-		t, http.StatusOK, w.Code,
-		"a different client IP must not be affected",
-	)
-}
-
-// TestReceiverRateLimit_RejectedRequestsCountTowardAggregate pins the
-// order the two limiters are chained in. The aggregate limiter has to
-// be the outer one, so that it counts requests the per-entrypoint
-// limiter rejects: those requests still arrive, and the aggregate
-// limit exists to bound what one address can make the receiver do.
-//
-// One path is hammered past the per-entrypoint limit, which alone
-// would leave the aggregate budget almost untouched; then a path the
-// client has never used must be rejected, which only the aggregate
-// limiter can do. Swap the two limiters and that last request is
-// served, because the rejected ones never reached the aggregate
-// limiter to be counted.
-func TestReceiverRateLimit_RejectedRequestsCountTowardAggregate(
-	t *testing.T,
-) {
-	t.Parallel()
-
-	const (
-		limit = 3
-		ip    = "6.6.6.8:1234"
-	)
-
-	aggregate := limit * middleware.ReceiverAggregateMultiplierConst
-
-	handler := receiverLimitedHandler(t, limit)
-
-	// Spend the whole aggregate budget on one path. Only the first
-	// limit requests are served; the rest are rejected by the
-	// per-entrypoint limiter but still count against the aggregate.
-	for i := range aggregate {
-		w := receiverPost(handler, ip, "/webhook/exhausted")
-
-		want := http.StatusTooManyRequests
-		if i < limit {
-			want = http.StatusOK
-		}
-
-		assert.Equal(
-			t, want, w.Code,
-			"request %d to the exhausted path", i,
-		)
-	}
-
-	w := receiverPost(handler, ip, "/webhook/never-used")
-	assert.Equal(
-		t, http.StatusTooManyRequests, w.Code,
-		"requests rejected per entrypoint must still count "+
-			"toward the aggregate limit, so the aggregate "+
-			"limiter has to run first",
-	)
-}
-
-// TestReceiverAggregateLimit_SaturatesOnOverflow covers the derived
-// aggregate limit for a configured per-entrypoint limit large enough
-// that multiplying it would wrap negative, which httprate would read
-// as a limit that rejects every request.
-func TestReceiverAggregateLimit_SaturatesOnOverflow(t *testing.T) {
-	t.Parallel()
-
-	assert.Equal(
-		t, 1200,
-		middleware.ReceiverAggregateLimitForTest(120),
-		"the default limit scales by the multiplier",
-	)
-	assert.Equal(
-		t, math.MaxInt,
-		middleware.ReceiverAggregateLimitForTest(math.MaxInt),
-		"an overflowing limit saturates instead of wrapping",
-	)
-}
-
 // TestReceiverRateLimit_IgnoresForwardedFromUntrustedPeer proves
 // the receiver limiter uses the same gated key function as the
 // POST limiters.