Method ServeHTTP

runtime/mux.go:407–553

ServeHTTP dispatches the request to the first handler whose pattern matches to r.Method and r.URL.Path.

(w http.ResponseWriter, r *http.Request)

// ServeHTTP dispatches the request to the first handler whose pattern matches to r.Method and r.URL.Path.
func (s *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	path := r.URL.Path
	if !strings.HasPrefix(path, "/") {
		_, outboundMarshaler := MarshalerForRequest(s, r)
		s.routingErrorHandler(ctx, s, outboundMarshaler, w, r, http.StatusBadRequest)
		return
	}

	// TODO(v3): remove UnescapingModeLegacy
	if s.unescapingMode != UnescapingModeLegacy && r.URL.RawPath != "" {
		path = r.URL.RawPath
	}

	if override := r.Header.Get("X-HTTP-Method-Override"); override != "" && !s.disableHTTPMethodOverride && s.isPathLengthFallback(r) {
		if err := r.ParseForm(); err != nil {
			_, outboundMarshaler := MarshalerForRequest(s, r)
			sterr := status.Error(codes.InvalidArgument, err.Error())
			s.errorHandler(ctx, s, outboundMarshaler, w, r, sterr)
			return
		}
		r.Method = strings.ToUpper(override)
	}

	var pathComponents []string
	// since in UnescapeModeLegacy, the URL will already have been fully unescaped, if we also split on "%2F"
	// in this escaping mode we would be double unescaping but in UnescapingModeAllCharacters, we still do as the
	// path is the RawPath (i.e. unescaped). That does mean that the behavior of this function will change its default
	// behavior when the UnescapingModeDefault gets changed from UnescapingModeLegacy to UnescapingModeAllExceptReserved
	if s.unescapingMode == UnescapingModeAllCharacters {
		pathComponents = encodedPathSplitter.Split(path[1:], -1)
	} else {
		pathComponents = strings.Split(path[1:], "/")
	}

	lastPathComponent := pathComponents[len(pathComponents)-1]

	for _, h := range s.handlers[r.Method] {
		// If the pattern has a verb, explicitly look for a suffix in the last
		// component that matches a colon plus the verb. This allows us to
		// handle some cases that otherwise can't be correctly handled by the
		// former LastIndex case, such as when the verb literal itself contains
		// a colon. This should work for all cases that have run through the
		// 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()

		idx := -1
		if patVerb != "" && strings.HasSuffix(lastPathComponent, ":"+patVerb) {
			idx = len(lastPathComponent) - len(patVerb) - 1
		}
		if idx == 0 {
			_, outboundMarshaler := MarshalerForRequest(s, r)
			s.routingErrorHandler(ctx, s, outboundMarshaler, w, r, http.StatusNotFound)