Fix raw path handling in strip prefix

middlewares/stripPrefix.go

@@ -16,8 +16,11 @@ type StripPrefix struct {
 
 func (s *StripPrefix) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	for _, prefix := range s.Prefixes {
-		if p := strings.TrimPrefix(r.URL.Path, prefix); len(p) < len(r.URL.Path) {
-			r.URL.Path = "/" + strings.TrimPrefix(p, "/")
+		if strings.HasPrefix(r.URL.Path, prefix) {
+			r.URL.Path = stripPrefix(r.URL.Path, prefix)
+			if r.URL.RawPath != "" {
+				r.URL.RawPath = stripPrefix(r.URL.RawPath, prefix)
+			}
 			s.serveRequest(w, r, strings.TrimSpace(prefix))
 			return
 		}
@@ -35,3 +38,11 @@ func (s *StripPrefix) serveRequest(w http.ResponseWriter, r *http.Request, prefi
 func (s *StripPrefix) SetHandler(Handler http.Handler) {
 	s.Handler = Handler
 }
+
+func stripPrefix(s, prefix string) string {
+	return ensureLeadingSlash(strings.TrimPrefix(s, prefix))
+}
+
+func ensureLeadingSlash(str string) string {
+	return "/" + strings.TrimPrefix(str, "/")
+}

middlewares/stripPrefixRegex.go

@@ -40,6 +40,9 @@ func (s *StripPrefixRegex) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		}
 
 		r.URL.Path = r.URL.Path[len(prefix.Path):]
+		if r.URL.RawPath != "" {
+			r.URL.RawPath = r.URL.RawPath[len(prefix.Path):]
+		}
 		r.Header.Add(ForwardedPrefixHeader, prefix.Path)
 		r.RequestURI = r.URL.RequestURI()
 		s.Handler.ServeHTTP(w, r)

middlewares/stripPrefixRegex_test.go

@@ -10,13 +10,13 @@ import (
 )
 
 func TestStripPrefixRegex(t *testing.T) {
-
 	testPrefixRegex := []string{"/a/api/", "/b/{regex}/", "/c/{category}/{id:[0-9]+}/"}
 
 	tests := []struct {
 		path               string
 		expectedStatusCode int
 		expectedPath       string
+		expectedRawPath    string
 		expectedHeader     string
 	}{
 		{
@@ -61,16 +61,24 @@ func TestStripPrefixRegex(t *testing.T) {
 			path:               "/c/api/abc/test4",
 			expectedStatusCode: http.StatusNotFound,
 		},
+		{
+			path:               "/a/api/a%2Fb",
+			expectedStatusCode: http.StatusOK,
+			expectedPath:       "a/b",
+			expectedRawPath:    "a%2Fb",
+			expectedHeader:     "/a/api/",
+		},
 	}
 
 	for _, test := range tests {
 		test := test
 		t.Run(test.path, func(t *testing.T) {
 			t.Parallel()
 
-			var actualPath, actualHeader string
+			var actualPath, actualRawPath, actualHeader string
 			handlerPath := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 				actualPath = r.URL.Path
+				actualRawPath = r.URL.RawPath
 				actualHeader = r.Header.Get(ForwardedPrefixHeader)
 			})
 			handler := NewStripPrefixRegex(handlerPath, testPrefixRegex)
@@ -82,6 +90,7 @@ func TestStripPrefixRegex(t *testing.T) {
 
 			assert.Equal(t, test.expectedStatusCode, resp.Code, "Unexpected status code.")
 			assert.Equal(t, test.expectedPath, actualPath, "Unexpected path.")
+			assert.Equal(t, test.expectedRawPath, actualRawPath, "Unexpected raw path.")
 			assert.Equal(t, test.expectedHeader, actualHeader, "Unexpected '%s' header.", ForwardedPrefixHeader)
 		})
 	}

middlewares/stripPrefix_test.go

@@ -16,6 +16,7 @@ func TestStripPrefix(t *testing.T) {
 		path               string
 		expectedStatusCode int
 		expectedPath       string
+		expectedRawPath    string
 		expectedHeader     string
 	}{
 		{
@@ -94,18 +95,28 @@ func TestStripPrefix(t *testing.T) {
 			expectedPath:       "/us",
 			expectedHeader:     "/stat",
 		},
+		{
+			desc:               "raw path is also stripped",
+			prefixes:           []string{"/stat"},
+			path:               "/stat/a%2Fb",
+			expectedStatusCode: http.StatusOK,
+			expectedPath:       "/a/b",
+			expectedRawPath:    "/a%2Fb",
+			expectedHeader:     "/stat",
+		},
 	}
 
 	for _, test := range tests {
 		test := test
 		t.Run(test.desc, func(t *testing.T) {
 			t.Parallel()
 
-			var actualPath, actualHeader, requestURI string
+			var actualPath, actualRawPath, actualHeader, requestURI string
 			handler := &StripPrefix{
 				Prefixes: test.prefixes,
 				Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 					actualPath = r.URL.Path
+					actualRawPath = r.URL.RawPath
 					actualHeader = r.Header.Get(ForwardedPrefixHeader)
 					requestURI = r.RequestURI
 				}),
@@ -118,8 +129,15 @@ func TestStripPrefix(t *testing.T) {
 
 			assert.Equal(t, test.expectedStatusCode, resp.Code, "Unexpected status code.")
 			assert.Equal(t, test.expectedPath, actualPath, "Unexpected path.")
+			assert.Equal(t, test.expectedRawPath, actualRawPath, "Unexpected raw path.")
 			assert.Equal(t, test.expectedHeader, actualHeader, "Unexpected '%s' header.", ForwardedPrefixHeader)
-			assert.Equal(t, test.expectedPath, requestURI, "Unexpected request URI.")
+
+			expectedURI := test.expectedPath
+			if test.expectedRawPath != "" {
+				// go HTTP uses the raw path when existent in the RequestURI
+				expectedURI = test.expectedRawPath
+			}
+			assert.Equal(t, expectedURI, requestURI, "Unexpected request URI.")
 		})
 	}
 }