mux: calculate verb correctly for cases like DELETE /foo/bar:archive …

…when user provided wrong method (grpc-ecosystem#2870)

* add failing test for DELETE /foo/bar:archive when method is wrong

The method the user meant was POST, which is supported. DELETE is not
supported, but I believe this should be NotImplemented, not NotFound.

* calculate verb in each handler

runtime/mux.go

@@ -343,8 +343,7 @@ func (s *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
  }
  }
 
- // Verb out here is to memoize for the fallback case below
- var verb string
+ lastComponent := components[len(components)-1]
 
  for _, h := range s.handlers[r.Method] {
  // If the pattern has a verb, explicitly look for a suffix in the last
@@ -355,10 +354,11 @@ func (s *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
  // parser because we know what verb we're looking for, however, there
  // are still some cases that the parser itself cannot disambiguate. See
  // the comment there if interested.
+
+ var verb string
  patVerb := h.pat.Verb()
- l := len(components)
- lastComponent := components[l-1]
- var idx int = -1
+
+ idx := -1
  if patVerb != "" && strings.HasSuffix(lastComponent, ":"+patVerb) {
  idx = len(lastComponent) - len(patVerb) - 1
  }
@@ -368,7 +368,7 @@ func (s *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
  return
  }
  if idx > 0 {
- components[l-1], verb = lastComponent[:idx], lastComponent[idx+1:]
+ components[len(components)-1], verb = lastComponent[:idx], lastComponent[idx+1:]
  }
 
  pathParams, err := h.pat.MatchAndEscape(components, verb, s.unescapingMode)
@@ -394,6 +394,17 @@ func (s *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
  continue
  }
  for _, h := range handlers {
+ var verb string
+ patVerb := h.pat.Verb()
+
+ idx := -1
+ if patVerb != "" && strings.HasSuffix(lastComponent, ":"+patVerb) {
+ idx = len(lastComponent) - len(patVerb) - 1
+ }
+ if idx > 0 {
+ components[len(components)-1], verb = lastComponent[:idx], lastComponent[idx+1:]
+ }
+
  pathParams, err := h.pat.MatchAndEscape(components, verb, s.unescapingMode)
  if err != nil {
  var mse MalformedSequenceError

runtime/mux_test.go

@@ -117,6 +117,19 @@ func TestMuxServeHTTP(t *testing.T) {
  reqPath: "/foo",
  respStatus: http.StatusNotImplemented,
  },
+ {
+ patterns: []stubPattern{
+ {
+ method: "POST",
+ ops: []int{int(utilities.OpLitPush), 0, int(utilities.OpPush), 0, int(utilities.OpConcatN), 1, int(utilities.OpCapture), 1},
+ pool: []string{"foo", "id"},
+ verb: "archive",
+ },
+ },
+ reqMethod: "DELETE",
+ reqPath: "/foo/bar:archive",
+ respStatus: http.StatusNotImplemented,
+ },
  {
  patterns: []stubPattern{
  {