Adding information about the client on the initial Websocket handshake

Question

I'm currently creating a distributed chat application. Everything works fine, meaning it's possible to send messages between the clients and the server and have it broadcasted appropiately.

However, at the moment only the actual message is sent to the server. I would like to add information about the user sending the message aswell.

I could add this information whenever I send a new message, but I would prefer if I could add this information during the initial handshake and then save this information on the backend.

I've thought about sending some information in the URL, but as I only instantiate the websocket once, this does not seem like the way to go. Similarly, I thought about adding the information as the body of the request, but I read that having a body on a GET request is usually not recommended.

So my question is, am I trying to do something that I should not be going for? Should I just send information about the client on each new message that is sent to the server?

Currently, my client looks like this:

const socket = new WebSocket("ws://localhost:8080/ws");

const connect = (cb) => {
    console.log("Attempting Connection...")

    socket.onopen = () => {
        console.log("Successfully Connected");
    }

    socket.onmessage = (msg) => {
        console.log(msg)
        cb(msg);
    }

    socket.onclose = (event) => {
        console.log("Socket Closed Connection: ", event);
    }

    socket.onerror = (error) => {
        console.log("Socket Error: ", error);
    }
};

const sendMsg = (msg) => {
    console.log("Sending msg: ", msg);
    socket.send(msg);
}

And the initial connection on the backend is handled by the following:

func serveWs(pool *websocket.Pool, w http.ResponseWriter, r *http.Request) {
    fmt.Println("WebSocket Endpoint Hit")

    conn, err := websocket.Upgrade(w, r)

    if err != nil {
        fmt.Fprintf(w, "%+V\n", err)
    }

    client := &websocket.Client{
        Name: "?????", // Obviously, I would like the actual name to be here.
        Conn: conn,
        Pool: pool,
    }

    pool.Register <- client

    client.Read()
}

Consider enforcing a "hello" protocol that the client must send as their first message. The server would drop all other messages until it receives a hello message from the client identifying the name. Does that make sense? — selbie, May 01 '22 at 02:03
@selbie it does make sense, but I think I would have to study protocols a bit more for now. Thanks for the suggestion, I will look into it. — niklasaa, May 01 '22 at 11:53

score 0 · Answer 1 · answered May 01 '22 at 12:01

The normal thing to do here as selbie pointed out is to expect from the client a special first message through WebSocket. If that message is not recived or does not meet the requirements the server ends the WebSocket conn.

Using socket.onopen is very common for this task.

More on why you cant put headers: HTTP headers in Websockets client API

Adding information about the client on the initial Websocket handshake

1 Answers1