Merge 38b9e10ecf into 91708ff8e3

mux.go

@@ -11,6 +11,7 @@ import (
 	"net/http"
 	"path"
 	"regexp"
+	"strings"
 )
 
 var (
@@ -202,7 +203,7 @@ func (r *Router) ServeHTTP(w http.ResponseWriter, req *http.Request) {
 	}
 
 	if handler == nil && match.MatchErr == ErrMethodMismatch {
-		handler = methodNotAllowedHandler()
+		handler = methodNotAllowedHandler(match.AllowedMethods)
 	}
 
 	if handler == nil {
@@ -417,6 +418,10 @@ type RouteMatch struct {
 	// It is set to ErrMethodMismatch if there is a mismatch in
 	// the request method and route method
 	MatchErr error
+
+	// AllowedMethods contains the list of methods allowed by a route when
+	// MatchErr is set to ErrMethodMismatch.
+	AllowedMethods []string
 }
 
 type contextKey int
@@ -598,11 +603,11 @@ func matchMapWithRegex(toCheck map[string]*regexp.Regexp, toMatch map[string][]s
 	return true
 }
 
-// methodNotAllowed replies to the request with an HTTP status code 405.
-func methodNotAllowed(w http.ResponseWriter, r *http.Request) {
-	w.WriteHeader(http.StatusMethodNotAllowed)
-}
-
 // methodNotAllowedHandler returns a simple request handler
 // that replies to each request with a status code 405.
-func methodNotAllowedHandler() http.Handler { return http.HandlerFunc(methodNotAllowed) }
+func methodNotAllowedHandler(allowed []string) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+		w.Header().Set("Allow", strings.Join(allowed, ","))
+		w.WriteHeader(http.StatusMethodNotAllowed)
+	})
+}

mux_test.go

@@ -2052,6 +2052,9 @@ func TestNoMatchMethodErrorHandler(t *testing.T) {
 	if resp.Code != http.StatusMethodNotAllowed {
 		t.Errorf("Expecting code %v", 405)
 	}
+	if hdr := resp.Header().Get("Allow"); hdr != "GET,POST" {
+		t.Errorf(`Expected Allow header to be "GET,POST" (got %q)`, hdr)
+	}
 
 	// Add matching route
 	r.HandleFunc("/", func1).Methods("PUT")
@@ -2721,7 +2724,6 @@ func TestMethodNotAllowed(t *testing.T) {
 	handler := func(w http.ResponseWriter, r *http.Request) { w.WriteHeader(http.StatusOK) }
 	router := NewRouter()
 	router.HandleFunc("/thing", handler).Methods(http.MethodGet)
-	router.HandleFunc("/something", handler).Methods(http.MethodGet)
 
 	w := NewRecorder()
 	req := newRequest(http.MethodPut, "/thing")
@@ -2731,6 +2733,9 @@ func TestMethodNotAllowed(t *testing.T) {
 	if w.Code != http.StatusMethodNotAllowed {
 		t.Fatalf("Expected status code 405 (got %d)", w.Code)
 	}
+	if hdr := w.Header().Get("Allow"); hdr != http.MethodGet {
+		t.Fatalf(`Expected Allow header to be "GET" (got %q)`, hdr)
+	}
 }
 
 type customMethodNotAllowedHandler struct {

route.go

@@ -44,12 +44,14 @@ func (r *Route) Match(req *http.Request, match *RouteMatch) bool {
 	}
 
 	var matchErr error
+	var allowedMethods []string
 
 	// Match everything.
 	for _, m := range r.matchers {
 		if matched := m.Match(req, match); !matched {
-			if _, ok := m.(methodMatcher); ok {
+			if m, ok := m.(methodMatcher); ok {
 				matchErr = ErrMethodMismatch
+				allowedMethods = m
 				continue
 			}
 
@@ -71,6 +73,9 @@ func (r *Route) Match(req *http.Request, match *RouteMatch) bool {
 
 	if matchErr != nil {
 		match.MatchErr = matchErr
+		if matchErr == ErrMethodMismatch {
+			match.AllowedMethods = allowedMethods
+		}
 		return false
 	}