refactor: replace custom CSRF and rate-limiting with off-the-shelf libraries

Replace custom CSRF middleware with gorilla/csrf and custom rate-limiting
middleware with go-chi/httprate, as requested in code review.

CSRF changes:
- Replace session-based CSRF tokens with gorilla/csrf cookie-based
  double-submit pattern (HMAC-authenticated cookies)
- Keep same form field name (csrf_token) for template compatibility
- Keep same route exclusions (webhook/API routes)
- In dev mode, mark requests as plaintext HTTP to skip Referer check

Rate limiting changes:
- Replace custom token-bucket rate limiter with httprate sliding-window
  counter (per-IP, 5 POST requests/min on login endpoint)
- Remove custom IP extraction (httprate.KeyByRealIP handles
  X-Forwarded-For, X-Real-IP, True-Client-IP)
- Remove custom cleanup goroutine (httprate manages its own state)

Kept as-is:
- SSRF prevention code (internal/delivery/ssrf.go) — application-specific
- CSRFToken() wrapper function — handlers unchanged

Updated README security section and architecture overview to reflect
library choices.

README.md

@@ -157,6 +157,10 @@ It uses:
   logging with TTY detection (text for dev, JSON for prod)
 - **[gorilla/sessions](https://github.com/gorilla/sessions)** for
   encrypted cookie-based session management
+- **[gorilla/csrf](https://github.com/gorilla/csrf)** for CSRF
+  protection (cookie-based double-submit tokens)
+- **[go-chi/httprate](https://github.com/go-chi/httprate)** for
+  per-IP login rate limiting (sliding window counter)
 - **[Prometheus](https://prometheus.io)** for metrics, served at
   `/metrics` behind basic auth
 - **[Sentry](https://sentry.io)** for optional error reporting
@@ -726,8 +730,8 @@ webhooker/
 │   │   └── logger.go          # slog setup with TTY detection
 │   ├── middleware/
 │   │   ├── middleware.go      # Logging, CORS, Auth, Metrics, MetricsAuth, SecurityHeaders, MaxBodySize
-│   │   ├── csrf.go            # CSRF protection middleware (session-based tokens)
+│   │   ├── csrf.go            # CSRF protection middleware (gorilla/csrf)
-│   │   └── ratelimit.go       # Per-IP rate limiting middleware (login endpoint)
+│   │   └── ratelimit.go       # Per-IP rate limiting middleware (go-chi/httprate)
 │   ├── server/
 │   │   ├── server.go          # Server struct, fx lifecycle, signal handling
 │   │   ├── http.go            # HTTP server setup with timeouts
@@ -814,17 +818,19 @@ Additionally, form endpoints (`/pages`, `/sources`, `/source/*`) apply a
   (`nosniff`), X-Frame-Options (`DENY`), Content-Security-Policy, Referrer-Policy,
   and Permissions-Policy
 - Request body size limits (1 MB) on all form POST endpoints
-- **CSRF protection** on all state-changing forms (session-based tokens
+- **CSRF protection** via [gorilla/csrf](https://github.com/gorilla/csrf)
-  with constant-time comparison). Applied to `/pages`, `/sources`,
+  on all state-changing forms (cookie-based double-submit tokens with
-  `/source`, and `/user` routes. Excluded from `/webhook` (inbound
+  HMAC authentication). Applied to `/pages`, `/sources`, `/source`, and
-  webhook POSTs) and `/api` (stateless API)
+  `/user` routes. Excluded from `/webhook` (inbound webhook POSTs) and
+  `/api` (stateless API)
 - **SSRF prevention** for HTTP delivery targets: private/reserved IP
   ranges (RFC 1918, loopback, link-local, cloud metadata) are blocked
   both at target creation time (URL validation) and at delivery time
   (custom HTTP transport with SSRF-safe dialer that validates resolved
   IPs before connecting, preventing DNS rebinding attacks)
-- **Login rate limiting**: per-IP rate limiter on the login endpoint
+- **Login rate limiting** via [go-chi/httprate](https://github.com/go-chi/httprate):
-  (5 attempts per minute per IP) to prevent brute-force attacks
+  per-IP sliding-window rate limiter on the login endpoint (5 POST
+  attempts per minute per IP) to prevent brute-force attacks
 - Prometheus metrics behind basic auth
 - Static assets embedded in binary (no filesystem access needed at
   runtime)

go.mod

@@ -9,7 +9,9 @@ require (
 	github.com/getsentry/sentry-go v0.25.0
 	github.com/go-chi/chi v1.5.5
 	github.com/go-chi/cors v1.2.1
+	github.com/go-chi/httprate v0.15.0
 	github.com/google/uuid v1.6.0
+	github.com/gorilla/csrf v1.7.3
 	github.com/gorilla/sessions v1.4.0
 	github.com/joho/godotenv v1.5.1
 	github.com/prometheus/client_golang v1.18.0
@@ -17,7 +19,6 @@ require (
 	github.com/stretchr/testify v1.8.4
 	go.uber.org/fx v1.20.1
 	golang.org/x/crypto v0.38.0
-	golang.org/x/time v0.14.0
 	gorm.io/driver/sqlite v1.5.4
 	gorm.io/gorm v1.25.5
 	modernc.org/sqlite v1.28.0
@@ -32,6 +33,7 @@ require (
 	github.com/jinzhu/inflection v1.0.0 // indirect
 	github.com/jinzhu/now v1.1.5 // indirect
 	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 // indirect
+	github.com/klauspost/cpuid/v2 v2.2.10 // indirect
 	github.com/kr/text v0.2.0 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
 	github.com/mattn/go-sqlite3 v1.14.17 // indirect
@@ -41,6 +43,7 @@ require (
 	github.com/prometheus/common v0.45.0 // indirect
 	github.com/prometheus/procfs v0.12.0 // indirect
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	github.com/zeebo/xxh3 v1.0.2 // indirect
 	go.uber.org/atomic v1.9.0 // indirect
 	go.uber.org/dig v1.17.0 // indirect
 	go.uber.org/multierr v1.9.0 // indirect

go.sum

@@ -19,6 +19,8 @@ github.com/go-chi/chi v1.5.5 h1:vOB/HbEMt9QqBqErz07QehcOKHaWFtuj87tTDVz2qXE=
 github.com/go-chi/chi v1.5.5/go.mod h1:C9JqLr3tIYjDOZpzn+BCuxY8z8vmca43EeMgyZt7irw=
 github.com/go-chi/cors v1.2.1 h1:xEC8UT3Rlp2QuWNEr4Fs/c2EAGVKBwy/1vHx3bppil4=
 github.com/go-chi/cors v1.2.1/go.mod h1:sSbTewc+6wYHBBCW7ytsFSn836hqM7JxpglAy2Vzc58=
+github.com/go-chi/httprate v0.15.0 h1:j54xcWV9KGmPf/X4H32/aTH+wBlrvxL7P+SdnRqxh5g=
+github.com/go-chi/httprate v0.15.0/go.mod h1:rzGHhVrsBn3IMLYDOZQsSU4fJNWcjui4fWKJcCId1R4=
 github.com/go-errors/errors v1.4.2 h1:J6MZopCL4uSllY1OfXM374weqZFFItUbrImctkmUxIA=
 github.com/go-errors/errors v1.4.2/go.mod h1:sIVyrIiJhuEF+Pj9Ebtd6P/rEYROXFi3BopGUQ5a5Og=
 github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
@@ -31,6 +33,8 @@ github.com/google/pprof v0.0.0-20221118152302-e6195bd50e26 h1:Xim43kblpZXfIBQsbu
 github.com/google/pprof v0.0.0-20221118152302-e6195bd50e26/go.mod h1:dDKJzRmX4S37WGHujM7tX//fmj1uioxKzKxz3lo4HJo=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/gorilla/csrf v1.7.3 h1:BHWt6FTLZAb2HtWT5KDBf6qgpZzvtbp9QWDRKZMXJC0=
+github.com/gorilla/csrf v1.7.3/go.mod h1:F1Fj3KG23WYHE6gozCmBAezKookxbIvUJT+121wTuLk=
 github.com/gorilla/securecookie v1.1.2 h1:YCIWL56dvtr73r6715mJs5ZvhtnY73hBvEF8kXD8ePA=
 github.com/gorilla/securecookie v1.1.2/go.mod h1:NfCASbcHqRSY+3a8tlWJwsQap2VX5pwzwo4h3eOamfo=
 github.com/gorilla/sessions v1.4.0 h1:kpIYOp/oi6MG/p5PgxApU8srsSw9tuFbt46Lt7auzqQ=
@@ -43,6 +47,8 @@ github.com/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
 github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 h1:Z9n2FFNUXsshfwJMBgNA0RU6/i7WVaAegv3PtuIHPMs=
 github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51/go.mod h1:CzGEWj7cYgsdH8dAjBGEr58BoE7ScuLd+fwFZ44+/x8=
+github.com/klauspost/cpuid/v2 v2.2.10 h1:tBs3QSyvjDyFTq3uoc/9xFpCuOsJQFNPiAhYdw2skhE=
+github.com/klauspost/cpuid/v2 v2.2.10/go.mod h1:hqwkgyIinND0mEev00jJYCxPNVRVXFQeu1XKlok6oO0=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
 github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
@@ -80,6 +86,10 @@ github.com/stretchr/objx v0.5.1/go.mod h1:/iHQpkQwBD6DLUmQ4pE+s1TXdob1mORJ4/UFdr
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+github.com/zeebo/assert v1.3.0 h1:g7C04CbJuIDKNPFHmsk4hwZDO5O+kntRxzaUoNXj+IQ=
+github.com/zeebo/assert v1.3.0/go.mod h1:Pq9JiuJQpG8JLJdtkwrJESF0Foym2/D9XMU5ciN/wJ0=
+github.com/zeebo/xxh3 v1.0.2 h1:xZmwmqxHZA8AI603jOQ0tMqmBr9lPeFwGg6d+xy9DC0=
+github.com/zeebo/xxh3 v1.0.2/go.mod h1:5NWz9Sef7zIDm2JHfFlcQvNekmcEl9ekUZQQKCYaDcA=
 go.uber.org/atomic v1.9.0 h1:ECmE8Bn/WFTYwEW/bpKD3M8VtR/zQVbavAoalC1PYyE=
 go.uber.org/atomic v1.9.0/go.mod h1:fEN4uk6kAWBTFdckzkM89CLk9XfWZrxpCo0nPH17wJc=
 go.uber.org/dig v1.17.0 h1:5Chju+tUvcC+N7N6EV08BJz41UZuO3BmHcN4A287ZLI=
@@ -103,8 +113,6 @@ golang.org/x/sys v0.33.0 h1:q3i8TbbEz+JRD9ywIRlyRAQbM0qF7hu24q3teo2hbuw=
 golang.org/x/sys v0.33.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
 golang.org/x/text v0.25.0 h1:qVyWApTSYLk/drJRO5mDlNYskwQznZmkpV2c8q9zls4=
 golang.org/x/text v0.25.0/go.mod h1:WEdwpYrmk1qmdHvhkSTNPm3app7v4rsT8F2UD6+VHIA=
-golang.org/x/time v0.14.0 h1:MRx4UaLrDotUKUdCIqzPC48t1Y9hANFKIRpNx+Te8PI=
-golang.org/x/time v0.14.0/go.mod h1:eL/Oa2bBBK0TkX57Fyni+NgnyQQN4LitPmob2Hjnqw4=
 golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d h1:vU5i/LfpvrRCpgM/VPfJLg5KjxD3E+hfT1SH+d9zLwg=
 golang.org/x/tools v0.21.1-0.20240508182429-e35e4ccd0d2d/go.mod h1:aiJjzUbINMkxbQROHiO6hDPo2LHcIPhhQsa9DLh0yGk=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

internal/middleware/csrf.go

@@ -1,102 +1,56 @@
 package middleware
 
 import (
-	"context"
-	"crypto/rand"
-	"crypto/subtle"
-	"encoding/hex"
 	"net/http"
+
+	"github.com/gorilla/csrf"
 )
 
-const (
-	// csrfTokenLength is the byte length of generated CSRF tokens.
-	// 32 bytes = 64 hex characters, providing 256 bits of entropy.
-	csrfTokenLength = 32
-
-	// csrfSessionKey is the session key where the CSRF token is stored.
-	csrfSessionKey = "csrf_token"
-
-	// csrfFormField is the HTML form field name for the CSRF token.
-	csrfFormField = "csrf_token"
-)
-
-// csrfContextKey is the context key type for CSRF tokens.
-type csrfContextKey struct{}
-
 // CSRFToken retrieves the CSRF token from the request context.
-// Returns an empty string if no token is present.
+// Returns an empty string if the gorilla/csrf middleware has not run.
 func CSRFToken(r *http.Request) string {
-	if token, ok := r.Context().Value(csrfContextKey{}).(string); ok {
+	return csrf.Token(r)
-		return token
-	}
-	return ""
 }
 
-// CSRF returns middleware that provides CSRF protection for state-changing
+// CSRF returns middleware that provides CSRF protection using the
-// requests. For every request, it ensures a CSRF token exists in the
+// gorilla/csrf library. The middleware uses the session authentication
-// session and makes it available via the request context. For POST, PUT,
+// key to sign a CSRF cookie and validates a masked token submitted via
-// PATCH, and DELETE requests, it validates the submitted csrf_token form
+// the "csrf_token" form field (or the "X-CSRF-Token" header) on
-// field against the session token. Requests with an invalid or missing
+// POST/PUT/PATCH/DELETE requests. Requests with an invalid or missing
 // token receive a 403 Forbidden response.
+//
+// In development mode, requests are marked as plaintext HTTP so that
+// gorilla/csrf skips the strict Referer-origin check (which is only
+// meaningful over TLS).
 func (m *Middleware) CSRF() func(http.Handler) http.Handler {
-	return func(next http.Handler) http.Handler {
+	protect := csrf.Protect(
-		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		m.session.GetKey(),
-			sess, err := m.session.Get(r)
+		csrf.FieldName("csrf_token"),
-			if err != nil {
+		csrf.Secure(!m.params.Config.IsDev()),
-				m.log.Error("csrf: failed to get session", "error", err)
+		csrf.SameSite(csrf.SameSiteLaxMode),
-				http.Error(w, "Forbidden", http.StatusForbidden)
+		csrf.Path("/"),
-				return
+		csrf.ErrorHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-			}
+			m.log.Warn("csrf: token validation failed",
-
-			// Ensure a CSRF token exists in the session
-			token, ok := sess.Values[csrfSessionKey].(string)
-			if !ok {
-				token = ""
-			}
-			if token == "" {
-				token, err = generateCSRFToken()
-				if err != nil {
-					m.log.Error("csrf: failed to generate token", "error", err)
-					http.Error(w, "Internal Server Error", http.StatusInternalServerError)
-					return
-				}
-				sess.Values[csrfSessionKey] = token
-				if saveErr := m.session.Save(r, w, sess); saveErr != nil {
-					m.log.Error("csrf: failed to save session", "error", saveErr)
-					http.Error(w, "Internal Server Error", http.StatusInternalServerError)
-					return
-				}
-			}
-
-			// Store token in context for templates
-			ctx := context.WithValue(r.Context(), csrfContextKey{}, token)
-			r = r.WithContext(ctx)
-
-			// Validate token on state-changing methods
-			switch r.Method {
-			case http.MethodPost, http.MethodPut, http.MethodPatch, http.MethodDelete:
-				submitted := r.FormValue(csrfFormField)
-				if subtle.ConstantTimeCompare([]byte(submitted), []byte(token)) != 1 {
-					m.log.Warn("csrf: token mismatch",
 				"method", r.Method,
 				"path", r.URL.Path,
 				"remote_addr", r.RemoteAddr,
+				"reason", csrf.FailureReason(r),
 			)
 			http.Error(w, "Forbidden - invalid CSRF token", http.StatusForbidden)
-					return
+		})),
-				}
+	)
-			}
 
-			next.ServeHTTP(w, r)
+	// In development (plaintext HTTP), signal gorilla/csrf to skip
+	// the strict TLS Referer check by injecting the PlaintextHTTP
+	// context key before the CSRF handler sees the request.
+	if m.params.Config.IsDev() {
+		return func(next http.Handler) http.Handler {
+			csrfHandler := protect(next)
+			return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				csrfHandler.ServeHTTP(w, csrf.PlaintextHTTPRequest(r))
 			})
 		}
-}
-
-// generateCSRFToken creates a cryptographically random hex-encoded token.
-func generateCSRFToken() (string, error) {
-	b := make([]byte, csrfTokenLength)
-	if _, err := rand.Read(b); err != nil {
-		return "", err
 	}
-	return hex.EncodeToString(b), nil
+
+	return protect
 }

internal/middleware/csrf_test.go

@@ -27,20 +27,19 @@ func TestCSRF_GETSetsToken(t *testing.T) {
 	handler.ServeHTTP(w, req)
 
 	assert.NotEmpty(t, gotToken, "CSRF token should be set in context on GET")
-	assert.Len(t, gotToken, csrfTokenLength*2, "CSRF token should be hex-encoded 32 bytes")
 }
 
 func TestCSRF_POSTWithValidToken(t *testing.T) {
 	t.Parallel()
 	m, _ := testMiddleware(t, config.EnvironmentDev)
 
-	// Use a separate handler for the GET to capture the token
+	// Capture the token from a GET request
 	var token string
-	getHandler := m.CSRF()(http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
+	csrfMiddleware := m.CSRF()
+	getHandler := csrfMiddleware(http.HandlerFunc(func(_ http.ResponseWriter, r *http.Request) {
 		token = CSRFToken(r)
 	}))
 
-	// GET to establish the session and capture token
 	getReq := httptest.NewRequest(http.MethodGet, "/form", nil)
 	getW := httptest.NewRecorder()
 	getHandler.ServeHTTP(getW, getReq)
@@ -49,14 +48,13 @@ func TestCSRF_POSTWithValidToken(t *testing.T) {
 	require.NotEmpty(t, cookies)
 	require.NotEmpty(t, token)
 
-	// POST handler that tracks whether it was called
+	// POST with valid token and cookies from the GET response
 	var called bool
-	postHandler := m.CSRF()(http.HandlerFunc(func(_ http.ResponseWriter, _ *http.Request) {
+	postHandler := csrfMiddleware(http.HandlerFunc(func(_ http.ResponseWriter, _ *http.Request) {
 		called = true
 	}))
 
-	// POST with valid token
+	form := url.Values{"csrf_token": {token}}
-	form := url.Values{csrfFormField: {token}}
 	postReq := httptest.NewRequest(http.MethodPost, "/form", strings.NewReader(form.Encode()))
 	postReq.Header.Set("Content-Type", "application/x-www-form-urlencoded")
 	for _, c := range cookies {
@@ -73,23 +71,21 @@ func TestCSRF_POSTWithoutToken(t *testing.T) {
 	t.Parallel()
 	m, _ := testMiddleware(t, config.EnvironmentDev)
 
-	// GET handler to establish session
+	csrfMiddleware := m.CSRF()
-	getHandler := m.CSRF()(http.HandlerFunc(func(_ http.ResponseWriter, _ *http.Request) {
-		// no-op — just establishes session
-	}))
 
+	// GET to establish the CSRF cookie
+	getHandler := csrfMiddleware(http.HandlerFunc(func(_ http.ResponseWriter, _ *http.Request) {}))
 	getReq := httptest.NewRequest(http.MethodGet, "/form", nil)
 	getW := httptest.NewRecorder()
 	getHandler.ServeHTTP(getW, getReq)
 	cookies := getW.Result().Cookies()
 
-	// POST handler that tracks whether it was called
+	// POST without CSRF token
 	var called bool
-	postHandler := m.CSRF()(http.HandlerFunc(func(_ http.ResponseWriter, _ *http.Request) {
+	postHandler := csrfMiddleware(http.HandlerFunc(func(_ http.ResponseWriter, _ *http.Request) {
 		called = true
 	}))
 
-	// POST without CSRF token
 	postReq := httptest.NewRequest(http.MethodPost, "/form", nil)
 	postReq.Header.Set("Content-Type", "application/x-www-form-urlencoded")
 	for _, c := range cookies {
@@ -107,24 +103,22 @@ func TestCSRF_POSTWithInvalidToken(t *testing.T) {
 	t.Parallel()
 	m, _ := testMiddleware(t, config.EnvironmentDev)
 
-	// GET handler to establish session
+	csrfMiddleware := m.CSRF()
-	getHandler := m.CSRF()(http.HandlerFunc(func(_ http.ResponseWriter, _ *http.Request) {
-		// no-op — just establishes session
-	}))
 
+	// GET to establish the CSRF cookie
+	getHandler := csrfMiddleware(http.HandlerFunc(func(_ http.ResponseWriter, _ *http.Request) {}))
 	getReq := httptest.NewRequest(http.MethodGet, "/form", nil)
 	getW := httptest.NewRecorder()
 	getHandler.ServeHTTP(getW, getReq)
 	cookies := getW.Result().Cookies()
 
-	// POST handler that tracks whether it was called
+	// POST with wrong CSRF token
 	var called bool
-	postHandler := m.CSRF()(http.HandlerFunc(func(_ http.ResponseWriter, _ *http.Request) {
+	postHandler := csrfMiddleware(http.HandlerFunc(func(_ http.ResponseWriter, _ *http.Request) {
 		called = true
 	}))
 
-	// POST with wrong CSRF token
+	form := url.Values{"csrf_token": {"invalid-token-value"}}
-	form := url.Values{csrfFormField: {"invalid-token-value"}}
 	postReq := httptest.NewRequest(http.MethodPost, "/form", strings.NewReader(form.Encode()))
 	postReq.Header.Set("Content-Type", "application/x-www-form-urlencoded")
 	for _, c := range cookies {
@@ -156,20 +150,8 @@ func TestCSRF_GETDoesNotValidate(t *testing.T) {
 	assert.True(t, called, "GET requests should pass through CSRF middleware")
 }
 
-func TestCSRFToken_NoContext(t *testing.T) {
+func TestCSRFToken_NoMiddleware(t *testing.T) {
 	t.Parallel()
 	req := httptest.NewRequest(http.MethodGet, "/", nil)
-	assert.Empty(t, CSRFToken(req), "CSRFToken should return empty string when no token in context")
+	assert.Empty(t, CSRFToken(req), "CSRFToken should return empty string when middleware has not run")
-}
-
-func TestGenerateCSRFToken(t *testing.T) {
-	t.Parallel()
-	token, err := generateCSRFToken()
-	require.NoError(t, err)
-	assert.Len(t, token, csrfTokenLength*2, "token should be hex-encoded")
-
-	// Verify uniqueness
-	token2, err := generateCSRFToken()
-	require.NoError(t, err)
-	assert.NotEqual(t, token, token2, "each generated token should be unique")
 }

internal/middleware/middleware_test.go

@@ -40,7 +40,7 @@ func testMiddleware(t *testing.T, env string) (*Middleware, *session.Session) {
 		SameSite: http.SameSiteLaxMode,
 	}
 
-	sessManager := newTestSession(t, store, cfg, log)
+	sessManager := newTestSession(t, store, cfg, log, key)
 
 	m := &Middleware{
 		log: log,
@@ -55,9 +55,9 @@ func testMiddleware(t *testing.T, env string) (*Middleware, *session.Session) {
 
 // newTestSession creates a session.Session with a pre-configured cookie store
 // for testing. This avoids needing the fx lifecycle and database.
-func newTestSession(t *testing.T, store *sessions.CookieStore, cfg *config.Config, log *slog.Logger) *session.Session {
+func newTestSession(t *testing.T, store *sessions.CookieStore, cfg *config.Config, log *slog.Logger, key []byte) *session.Session {
 	t.Helper()
-	return session.NewForTest(store, cfg, log)
+	return session.NewForTest(store, cfg, log, key)
 }
 
 // --- Logging Middleware Tests ---
@@ -326,7 +326,7 @@ func TestMetricsAuth_ValidCredentials(t *testing.T) {
 	store := sessions.NewCookieStore(key)
 	store.Options = &sessions.Options{Path: "/", MaxAge: 86400}
 
-	sessManager := session.NewForTest(store, cfg, log)
+	sessManager := session.NewForTest(store, cfg, log, key)
 
 	m := &Middleware{
 		log: log,
@@ -366,7 +366,7 @@ func TestMetricsAuth_InvalidCredentials(t *testing.T) {
 	store := sessions.NewCookieStore(key)
 	store.Options = &sessions.Options{Path: "/", MaxAge: 86400}
 
-	sessManager := session.NewForTest(store, cfg, log)
+	sessManager := session.NewForTest(store, cfg, log, key)
 
 	m := &Middleware{
 		log: log,
@@ -406,7 +406,7 @@ func TestMetricsAuth_NoCredentials(t *testing.T) {
 	store := sessions.NewCookieStore(key)
 	store.Options = &sessions.Options{Path: "/", MaxAge: 86400}
 
-	sessManager := session.NewForTest(store, cfg, log)
+	sessManager := session.NewForTest(store, cfg, log, key)
 
 	m := &Middleware{
 		log: log,

internal/middleware/ratelimit.go

@@ -1,12 +1,10 @@
 package middleware
 
 import (
-	"net"
 	"net/http"
-	"sync"
 	"time"
 
-	"golang.org/x/time/rate"
+	"github.com/go-chi/httprate"
 )
 
 const (
@@ -15,158 +13,36 @@ const (
 
 	// loginRateInterval is the time window for the rate limit.
 	loginRateInterval = 1 * time.Minute
-
-	// limiterCleanupInterval is how often stale per-IP limiters are pruned.
-	limiterCleanupInterval = 5 * time.Minute
-
-	// limiterMaxAge is how long an unused limiter is kept before pruning.
-	limiterMaxAge = 10 * time.Minute
 )
 
-// ipLimiter holds a rate limiter and the time it was last used.
-type ipLimiter struct {
-	limiter  *rate.Limiter
-	lastSeen time.Time
-}
-
-// rateLimiterMap manages per-IP rate limiters with periodic cleanup.
-type rateLimiterMap struct {
-	mu       sync.Mutex
-	limiters map[string]*ipLimiter
-	rate     rate.Limit
-	burst    int
-}
-
-// newRateLimiterMap creates a new per-IP rate limiter map.
-func newRateLimiterMap(r rate.Limit, burst int) *rateLimiterMap {
-	rlm := &rateLimiterMap{
-		limiters: make(map[string]*ipLimiter),
-		rate:     r,
-		burst:    burst,
-	}
-
-	// Start background cleanup goroutine
-	go rlm.cleanup()
-
-	return rlm
-}
-
-// getLimiter returns the rate limiter for the given IP, creating one if
-// it doesn't exist.
-func (rlm *rateLimiterMap) getLimiter(ip string) *rate.Limiter {
-	rlm.mu.Lock()
-	defer rlm.mu.Unlock()
-
-	if entry, ok := rlm.limiters[ip]; ok {
-		entry.lastSeen = time.Now()
-		return entry.limiter
-	}
-
-	limiter := rate.NewLimiter(rlm.rate, rlm.burst)
-	rlm.limiters[ip] = &ipLimiter{
-		limiter:  limiter,
-		lastSeen: time.Now(),
-	}
-	return limiter
-}
-
-// cleanup periodically removes stale rate limiters to prevent unbounded
-// memory growth from unique IPs.
-func (rlm *rateLimiterMap) cleanup() {
-	ticker := time.NewTicker(limiterCleanupInterval)
-	defer ticker.Stop()
-
-	for range ticker.C {
-		rlm.mu.Lock()
-		cutoff := time.Now().Add(-limiterMaxAge)
-		for ip, entry := range rlm.limiters {
-			if entry.lastSeen.Before(cutoff) {
-				delete(rlm.limiters, ip)
-			}
-		}
-		rlm.mu.Unlock()
-	}
-}
-
 // LoginRateLimit returns middleware that enforces per-IP rate limiting
-// on login attempts. Only POST requests are rate-limited; GET requests
+// on login attempts using go-chi/httprate. Only POST requests are
-// (rendering the login form) pass through unaffected. When the rate
+// rate-limited; GET requests (rendering the login form) pass through
-// limit is exceeded, a 429 Too Many Requests response is returned.
+// unaffected. When the rate limit is exceeded, a 429 Too Many Requests
+// response is returned. IP extraction honours X-Forwarded-For,
+// X-Real-IP, and True-Client-IP headers for reverse-proxy setups.
 func (m *Middleware) LoginRateLimit() func(http.Handler) http.Handler {
-	// Calculate rate: loginRateLimit events per loginRateInterval
+	limiter := httprate.Limit(
-	r := rate.Limit(float64(loginRateLimit) / loginRateInterval.Seconds())
+		loginRateLimit,
-	rlm := newRateLimiterMap(r, loginRateLimit)
+		loginRateInterval,
+		httprate.WithKeyFuncs(httprate.KeyByRealIP),
+		httprate.WithLimitHandler(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			m.log.Warn("login rate limit exceeded",
+				"path", r.URL.Path,
+			)
+			http.Error(w, "Too many login attempts. Please try again later.", http.StatusTooManyRequests)
+		})),
+	)
 
 	return func(next http.Handler) http.Handler {
+		limited := limiter(next)
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			// Only rate-limit POST requests (actual login attempts)
 			if r.Method != http.MethodPost {
 				next.ServeHTTP(w, r)
 				return
 			}
-
+			limited.ServeHTTP(w, r)
-			ip := extractIP(r)
-			limiter := rlm.getLimiter(ip)
-
-			if !limiter.Allow() {
-				m.log.Warn("login rate limit exceeded",
-					"ip", ip,
-					"path", r.URL.Path,
-				)
-				http.Error(w, "Too many login attempts. Please try again later.", http.StatusTooManyRequests)
-				return
-			}
-
-			next.ServeHTTP(w, r)
 		})
 	}
 }
-
-// extractIP extracts the client IP address from the request. It checks
-// X-Forwarded-For and X-Real-IP headers first (for reverse proxy setups),
-// then falls back to RemoteAddr.
-func extractIP(r *http.Request) string {
-	// Check X-Forwarded-For header (first IP in chain)
-	if xff := r.Header.Get("X-Forwarded-For"); xff != "" {
-		// X-Forwarded-For can contain multiple IPs: client, proxy1, proxy2
-		// The first one is the original client
-		for i := 0; i < len(xff); i++ {
-			if xff[i] == ',' {
-				ip := xff[:i]
-				// Trim whitespace
-				for len(ip) > 0 && ip[0] == ' ' {
-					ip = ip[1:]
-				}
-				for len(ip) > 0 && ip[len(ip)-1] == ' ' {
-					ip = ip[:len(ip)-1]
-				}
-				if ip != "" {
-					return ip
-				}
-				break
-			}
-		}
-		trimmed := xff
-		for len(trimmed) > 0 && trimmed[0] == ' ' {
-			trimmed = trimmed[1:]
-		}
-		for len(trimmed) > 0 && trimmed[len(trimmed)-1] == ' ' {
-			trimmed = trimmed[:len(trimmed)-1]
-		}
-		if trimmed != "" {
-			return trimmed
-		}
-	}
-
-	// Check X-Real-IP header
-	if xri := r.Header.Get("X-Real-IP"); xri != "" {
-		return xri
-	}
-
-	// Fall back to RemoteAddr
-	ip, _, err := net.SplitHostPort(r.RemoteAddr)
-	if err != nil {
-		return r.RemoteAddr
-	}
-	return ip
-}

internal/middleware/ratelimit_test.go

@@ -88,34 +88,3 @@ func TestLoginRateLimit_IndependentPerIP(t *testing.T) {
 	handler.ServeHTTP(w2, req2)
 	assert.Equal(t, http.StatusOK, w2.Code, "different IP should not be affected")
 }
-
-func TestExtractIP_RemoteAddr(t *testing.T) {
-	t.Parallel()
-	req := httptest.NewRequest(http.MethodGet, "/", nil)
-	req.RemoteAddr = "192.168.1.100:54321"
-	assert.Equal(t, "192.168.1.100", extractIP(req))
-}
-
-func TestExtractIP_XForwardedFor(t *testing.T) {
-	t.Parallel()
-	req := httptest.NewRequest(http.MethodGet, "/", nil)
-	req.RemoteAddr = "10.0.0.1:1234"
-	req.Header.Set("X-Forwarded-For", "203.0.113.50, 70.41.3.18, 150.172.238.178")
-	assert.Equal(t, "203.0.113.50", extractIP(req))
-}
-
-func TestExtractIP_XRealIP(t *testing.T) {
-	t.Parallel()
-	req := httptest.NewRequest(http.MethodGet, "/", nil)
-	req.RemoteAddr = "10.0.0.1:1234"
-	req.Header.Set("X-Real-IP", "203.0.113.50")
-	assert.Equal(t, "203.0.113.50", extractIP(req))
-}
-
-func TestExtractIP_XForwardedForSingle(t *testing.T) {
-	t.Parallel()
-	req := httptest.NewRequest(http.MethodGet, "/", nil)
-	req.RemoteAddr = "10.0.0.1:1234"
-	req.Header.Set("X-Forwarded-For", "203.0.113.50")
-	assert.Equal(t, "203.0.113.50", extractIP(req))
-}

internal/session/session.go

@@ -39,6 +39,7 @@ type SessionParams struct {
 // Session manages encrypted session storage
 type Session struct {
 	store  *sessions.CookieStore
+	key    []byte // raw 32-byte auth key, also used for CSRF cookie signing
 	log    *slog.Logger
 	config *config.Config
 }
@@ -79,6 +80,7 @@ func New(lc fx.Lifecycle, params SessionParams) (*Session, error) {
 				SameSite: http.SameSiteLaxMode,
 			}
 
+			s.key = keyBytes
 			s.store = store
 			s.log.Info("session manager initialized")
 			return nil
@@ -93,6 +95,12 @@ func (s *Session) Get(r *http.Request) (*sessions.Session, error) {
 	return s.store.Get(r, SessionName)
 }
 
+// GetKey returns the raw 32-byte authentication key used for session
+// encryption. This key is also suitable for CSRF cookie signing.
+func (s *Session) GetKey() []byte {
+	return s.key
+}
+
 // Save saves the session
 func (s *Session) Save(r *http.Request, w http.ResponseWriter, sess *sessions.Session) error {
 	return sess.Save(r, w)

internal/session/session_test.go

@@ -34,7 +34,7 @@ func testSession(t *testing.T) *Session {
 	}
 	log := slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelDebug}))
 
-	return NewForTest(store, cfg, log)
+	return NewForTest(store, cfg, log, key)
 }
 
 // --- Get and Save Tests ---

internal/session/testing.go

@@ -9,10 +9,13 @@ import (
 
 // NewForTest creates a Session with a pre-configured cookie store for use
 // in tests. This bypasses the fx lifecycle and database dependency, allowing
-// middleware and handler tests to use real session functionality.
+// middleware and handler tests to use real session functionality. The key
-func NewForTest(store *sessions.CookieStore, cfg *config.Config, log *slog.Logger) *Session {
+// parameter is the raw 32-byte authentication key used for session encryption
+// and CSRF cookie signing.
+func NewForTest(store *sessions.CookieStore, cfg *config.Config, log *slog.Logger, key []byte) *Session {
 	return &Session{
 		store:  store,
+		key:    key,
 		config: cfg,
 		log:    log,
 	}