add standard http middleware support (#113)

Author: umputun

tollbooth.go

@@ -346,3 +346,30 @@ func LimitHandler(lmt *limiter.Limiter, next http.Handler) http.Handler {
 func LimitFuncHandler(lmt *limiter.Limiter, nextFunc func(http.ResponseWriter, *http.Request)) http.Handler {
 	return LimitHandler(lmt, http.HandlerFunc(nextFunc))
 }
+
+// HTTPMiddleware wraps http.Handler with tollbooth limiter
+func HTTPMiddleware(lmt *limiter.Limiter) func(http.Handler) http.Handler {
+	// // set IP lookup only if not set
+	if lmt.GetIPLookup().Name == "" {
+		lmt.SetIPLookup(limiter.IPLookup{Name: "RemoteAddr"})
+	}
+
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			select {
+			case <-r.Context().Done():
+				http.Error(w, "Context was canceled", http.StatusServiceUnavailable)
+				return
+			default:
+				if httpError := LimitByRequest(lmt, w, r); httpError != nil {
+					lmt.ExecOnLimitReached(w, r)
+					w.Header().Add("Content-Type", lmt.GetMessageContentType())
+					w.WriteHeader(httpError.StatusCode)
+					w.Write([]byte(httpError.Message)) //nolint:gosec // not much we can do here with failed write
+					return
+				}
+				next.ServeHTTP(w, r)
+			}
+		})
+	}
+}

tollbooth_test.go

@@ -653,3 +653,137 @@ func TestLimitHandlerEmptyHeader(t *testing.T) {
 
 	wg.Wait() // Block until go func is done.
 }
+
+func TestHTTPMiddleware(t *testing.T) {
+	t.Run("basic request", func(t *testing.T) {
+		lmt := NewLimiter(1, nil)
+		handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+			w.WriteHeader(http.StatusOK)
+		})
+		wrapped := HTTPMiddleware(lmt)(handler)
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest(http.MethodGet, "/test", nil)
+		r.RemoteAddr = "127.0.0.1:12345"
+		wrapped.ServeHTTP(w, r)
+		if w.Code != http.StatusOK {
+			t.Errorf("expected status %d, got %d", http.StatusOK, w.Code)
+		}
+	})
+
+	t.Run("rate limit exceeded", func(t *testing.T) {
+		lmt := NewLimiter(0.1, nil) // only allow one request per 10 seconds
+		handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+			w.WriteHeader(http.StatusOK)
+		})
+		wrapped := HTTPMiddleware(lmt)(handler)
+
+		// first request
+		w1 := httptest.NewRecorder()
+		r1 := httptest.NewRequest(http.MethodGet, "/test", nil)
+		r1.RemoteAddr = "127.0.0.1:12345"
+		wrapped.ServeHTTP(w1, r1)
+		if w1.Code != http.StatusOK {
+			t.Errorf("first request: expected status %d, got %d", http.StatusOK, w1.Code)
+		}
+
+		// immediate second request should fail
+		w2 := httptest.NewRecorder()
+		r2 := httptest.NewRequest(http.MethodGet, "/test", nil)
+		r2.RemoteAddr = "127.0.0.1:12345"
+		wrapped.ServeHTTP(w2, r2)
+		if w2.Code != http.StatusTooManyRequests {
+			t.Errorf("second request: expected status %d, got %d", http.StatusTooManyRequests, w2.Code)
+		}
+		if !strings.Contains(w2.Body.String(), "maximum request limit") {
+			t.Errorf("expected error message containing 'maximum request limit', got %q", w2.Body.String())
+		}
+	})
+
+	t.Run("context cancelled", func(t *testing.T) {
+		lmt := NewLimiter(1, nil)
+		handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+			w.WriteHeader(http.StatusOK)
+		})
+		wrapped := HTTPMiddleware(lmt)(handler)
+		w := httptest.NewRecorder()
+		r := httptest.NewRequest(http.MethodGet, "/test", nil)
+		ctx, cancel := context.WithCancel(r.Context())
+		cancel()
+		r = r.WithContext(ctx)
+		wrapped.ServeHTTP(w, r)
+		if w.Code != http.StatusServiceUnavailable {
+			t.Errorf("expected status %d, got %d", http.StatusServiceUnavailable, w.Code)
+		}
+		if !strings.Contains(w.Body.String(), "Context was canceled") {
+			t.Errorf("expected error message containing 'Context was canceled', got %q", w.Body.String())
+		}
+	})
+
+	t.Run("custom error handler", func(t *testing.T) {
+		lmt := NewLimiter(0.1, nil) // only allow one request per 10 seconds
+		customMsg := "custom limit reached"
+		lmt.SetMessage(customMsg)
+
+		handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+			w.WriteHeader(http.StatusOK)
+		})
+		wrapped := HTTPMiddleware(lmt)(handler)
+
+		// first request
+		w1 := httptest.NewRecorder()
+		r1 := httptest.NewRequest(http.MethodGet, "/test", nil)
+		r1.RemoteAddr = "127.0.0.1:12345"
+		wrapped.ServeHTTP(w1, r1)
+		if w1.Code != http.StatusOK {
+			t.Errorf("first request: expected status %d, got %d", http.StatusOK, w1.Code)
+		}
+
+		// immediate second request should fail
+		w2 := httptest.NewRecorder()
+		r2 := httptest.NewRequest(http.MethodGet, "/test", nil)
+		r2.RemoteAddr = "127.0.0.1:12345"
+		wrapped.ServeHTTP(w2, r2)
+		if w2.Code != http.StatusTooManyRequests {
+			t.Errorf("second request: expected status %d, got %d", http.StatusTooManyRequests, w2.Code)
+		}
+		if !strings.Contains(w2.Body.String(), customMsg) {
+			t.Errorf("expected error message containing %q, got %q", customMsg, w2.Body.String())
+		}
+	})
+
+	t.Run("custom IP lookup", func(t *testing.T) {
+		lmt := NewLimiter(0.1, nil)
+		lmt.SetIPLookup(limiter.IPLookup{Name: "X-Real-IP"})
+		handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+			w.WriteHeader(http.StatusOK)
+		})
+		wrapped := HTTPMiddleware(lmt)(handler)
+
+		// first request with IP1
+		w1 := httptest.NewRecorder()
+		r1 := httptest.NewRequest(http.MethodGet, "/test", nil)
+		r1.Header.Set("X-Real-IP", "5.5.5.5")
+		wrapped.ServeHTTP(w1, r1)
+		if w1.Code != http.StatusOK {
+			t.Errorf("first request: expected status %d, got %d", http.StatusOK, w1.Code)
+		}
+
+		// second request with IP1 should fail
+		w2 := httptest.NewRecorder()
+		r2 := httptest.NewRequest(http.MethodGet, "/test", nil)
+		r2.Header.Set("X-Real-IP", "5.5.5.5")
+		wrapped.ServeHTTP(w2, r2)
+		if w2.Code != http.StatusTooManyRequests {
+			t.Errorf("second request: expected status %d, got %d", http.StatusTooManyRequests, w2.Code)
+		}
+
+		// request with IP2 should pass
+		w3 := httptest.NewRecorder()
+		r3 := httptest.NewRequest(http.MethodGet, "/test", nil)
+		r3.Header.Set("X-Real-IP", "6.6.6.6")
+		wrapped.ServeHTTP(w3, r3)
+		if w3.Code != http.StatusOK {
+			t.Errorf("third request: expected status %d, got %d", http.StatusOK, w3.Code)
+		}
+	})
+}