timeout errors are unrecoverable

[gorilla]

timeout errors are unrecoverable

[garyburd]

Recoverable timeouts are difficult to implement. I am not aware of other Go network protocol libraries that support recoverable timeouts.

The application can implement timeout polling in a net.Conn shim between the websocket.Conn and the underlying net.Conn. A sketch for creating the shim is:

type appResponseWriter struct {  http.ResponseWriter }

func (w appResponseWriter)  Hijack() (net.Conn, *bufio.ReadWriter, error) {
    if h, ok := w.ResponseWriter.(http.Hijacker); ok {
        c, brw, err := h.Hijack()
        c = appConn(c)
        return c, brw, err
   } else {
        return nil, nil, errors.New("not supported")
   }
}

type appConn struct {
    net.Conn
}

func (c appConn) Read(p []byte) (int, err) {
    // implement timeout polling here.
}

func handler(w http.ResponseWriter, r *http.Request) {
    ws, err := websocket.Upgrade(appResponseWriter{w}, r, nil, 1024, 1024)
    if _, ok := err.(websocket.HandshakeError); ok {
        http.Error(w, "Not a websocket handshake", 400)
        return
    } else if err != nil {
        log.Println(err)
        return
    }
    ... Use conn to send and receive messages.
}

[garyburd]

It is not idiomatic to poll connections with timeouts in Go.

Close the websocket connection one minute after writing the close message. This will cause a blocked reader to return with an error.