Method ServeHTTP

handler.go:259–338

ServeHTTP implements [http.Handler].

(responseWriter http.ResponseWriter, request *http.Request)

// ServeHTTP implements [http.Handler].
func (h *Handler) ServeHTTP(responseWriter http.ResponseWriter, request *http.Request) {
	// We don't need to defer functions to close the request body or read to
	// EOF: the stream we construct later on already does that, and we only
	// return early when dealing with misbehaving clients. In those cases, it's
	// okay if we can't re-use the connection.
	isBidi := (h.spec.StreamType & StreamTypeBidi) == StreamTypeBidi
	if isBidi && request.ProtoMajor < 2 {
		// Clients coded to expect full-duplex connections may hang if they've
		// mistakenly negotiated HTTP/1.1. To unblock them, we must close the
		// underlying TCP connection.
		responseWriter.Header().Set("Connection", "close")
		responseWriter.WriteHeader(http.StatusHTTPVersionNotSupported)
		return
	}

	protocolHandlers := h.protocolHandlers[request.Method]
	if len(protocolHandlers) == 0 {
		responseWriter.Header().Set("Allow", h.allowMethod)
		responseWriter.WriteHeader(http.StatusMethodNotAllowed)
		return
	}

	contentType := canonicalizeContentType(getHeaderCanonical(request.Header, headerContentType))

	// Find our implementation of the RPC protocol in use.
	var protocolHandler protocolHandler
	for _, handler := range protocolHandlers {
		if handler.CanHandlePayload(request, contentType) {
			protocolHandler = handler
			break
		}
	}
	if protocolHandler == nil {
		responseWriter.Header().Set("Accept-Post", h.acceptPost)
		responseWriter.WriteHeader(http.StatusUnsupportedMediaType)
		return
	}

	if request.Method == http.MethodGet {
		// A body must not be present.
		hasBody := request.ContentLength > 0
		if request.ContentLength < 0 {
			// No content-length header.
			// Test if body is empty by trying to read a single byte.
			var b [1]byte
			n, _ := request.Body.Read(b[:])
			hasBody = n > 0
		}
		if hasBody {
			responseWriter.WriteHeader(http.StatusUnsupportedMediaType)
			return
		}
		_ = request.Body.Close()
	}

	// Establish a stream and serve the RPC.
	setHeaderCanonical(request.Header, headerContentType, contentType)
	setHeaderCanonical(request.Header, headerHost, request.Host)