Added WithDisablePathLengthFallback option (to fix issue #447) (#855)

Author: Uladzimir Trehubenka

runtime/mux.go

@@ -20,13 +20,14 @@ type HandlerFunc func(w http.ResponseWriter, r *http.Request, pathParams map[str
 // It matches http requests to patterns and invokes the corresponding handler.
 type ServeMux struct {
 	// handlers maps HTTP method to a list of handlers.
-	handlers               map[string][]handler
-	forwardResponseOptions []func(context.Context, http.ResponseWriter, proto.Message) error
-	marshalers             marshalerRegistry
-	incomingHeaderMatcher  HeaderMatcherFunc
-	outgoingHeaderMatcher  HeaderMatcherFunc
-	metadataAnnotators     []func(context.Context, *http.Request) metadata.MD
-	protoErrorHandler      ProtoErrorHandlerFunc
+	handlers                  map[string][]handler
+	forwardResponseOptions    []func(context.Context, http.ResponseWriter, proto.Message) error
+	marshalers                marshalerRegistry
+	incomingHeaderMatcher     HeaderMatcherFunc
+	outgoingHeaderMatcher     HeaderMatcherFunc
+	metadataAnnotators        []func(context.Context, *http.Request) metadata.MD
+	protoErrorHandler         ProtoErrorHandlerFunc
+	disablePathLengthFallback bool
 }
 
 // ServeMuxOption is an option that can be given to a ServeMux on construction.
@@ -102,6 +103,13 @@ func WithProtoErrorHandler(fn ProtoErrorHandlerFunc) ServeMuxOption {
 	}
 }
 
+// WithDisablePathLengthFallback returns a ServeMuxOption for disable path length fallback.
+func WithDisablePathLengthFallback() ServeMuxOption {
+	return func(serveMux *ServeMux) {
+		serveMux.disablePathLengthFallback = true
+	}
+}
+
 // NewServeMux returns a new ServeMux whose internal mapping is empty.
 func NewServeMux(opts ...ServeMuxOption) *ServeMux {
 	serveMux := &ServeMux{
@@ -177,7 +185,7 @@ func (s *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		components[l-1], verb = c[:idx], c[idx+1:]
 	}
 
-	if override := r.Header.Get("X-HTTP-Method-Override"); override != "" && isPathLengthFallback(r) {
+	if override := r.Header.Get("X-HTTP-Method-Override"); override != "" && s.isPathLengthFallback(r) {
 		r.Method = strings.ToUpper(override)
 		if err := r.ParseForm(); err != nil {
 			if s.protoErrorHandler != nil {
@@ -211,7 +219,7 @@ func (s *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 				continue
 			}
 			// X-HTTP-Method-Override is optional. Always allow fallback to POST.
-			if isPathLengthFallback(r) {
+			if s.isPathLengthFallback(r) {
 				if err := r.ParseForm(); err != nil {
 					if s.protoErrorHandler != nil {
 						_, outboundMarshaler := MarshalerForRequest(s, r)
@@ -250,8 +258,8 @@ func (s *ServeMux) GetForwardResponseOptions() []func(context.Context, http.Resp
 	return s.forwardResponseOptions
 }
 
-func isPathLengthFallback(r *http.Request) bool {
-	return r.Method == "POST" && r.Header.Get("Content-Type") == "application/x-www-form-urlencoded"
+func (s *ServeMux) isPathLengthFallback(r *http.Request) bool {
+	return !s.disablePathLengthFallback && r.Method == "POST" && r.Header.Get("Content-Type") == "application/x-www-form-urlencoded"
 }
 
 type handler struct {

runtime/mux_test.go

@@ -27,6 +27,8 @@ func TestMuxServeHTTP(t *testing.T) {
 
 		respStatus  int
 		respContent string
+
+		disablePathLengthFallback bool
 	}{
 		{
 			patterns:   nil,
@@ -122,6 +124,45 @@ func TestMuxServeHTTP(t *testing.T) {
 			respStatus:  http.StatusOK,
 			respContent: "GET /foo",
 		},
+		{
+			patterns: []stubPattern{
+				{
+					method: "GET",
+					ops:    []int{int(utilities.OpLitPush), 0},
+					pool:   []string{"foo"},
+				},
+			},
+			reqMethod: "POST",
+			reqPath:   "/foo",
+			headers: map[string]string{
+				"Content-Type": "application/x-www-form-urlencoded",
+			},
+			respStatus:                http.StatusMethodNotAllowed,
+			respContent:               "Method Not Allowed\n",
+			disablePathLengthFallback: true,
+		},
+		{
+			patterns: []stubPattern{
+				{
+					method: "GET",
+					ops:    []int{int(utilities.OpLitPush), 0},
+					pool:   []string{"foo"},
+				},
+				{
+					method: "POST",
+					ops:    []int{int(utilities.OpLitPush), 0},
+					pool:   []string{"foo"},
+				},
+			},
+			reqMethod: "POST",
+			reqPath:   "/foo",
+			headers: map[string]string{
+				"Content-Type": "application/x-www-form-urlencoded",
+			},
+			respStatus:                http.StatusOK,
+			respContent:               "POST /foo",
+			disablePathLengthFallback: true,
+		},
 		{
 			patterns: []stubPattern{
 				{
@@ -199,7 +240,11 @@ func TestMuxServeHTTP(t *testing.T) {
 			respContent: "GET /foo/{id=*}:verb",
 		},
 	} {
-		mux := runtime.NewServeMux()
+		var opts []runtime.ServeMuxOption
+		if spec.disablePathLengthFallback {
+			opts = append(opts, runtime.WithDisablePathLengthFallback())
+		}
+		mux := runtime.NewServeMux(opts...)
 		for _, p := range spec.patterns {
 			func(p stubPattern) {
 				pat, err := runtime.NewPattern(1, p.ops, p.pool, p.verb)