Question

I’m trying to set up a websocket server in node.js but having problems. I found a bit code here on stackoverflow and heres the servercode I have now:

var net = require("net"), crypto = require("crypto"), users = [];

net.createServer(function(socket) {
    this.name = "Anonymous";
    users.push(socket);     

    socket.on('data', function(buffer) {
        if(buffer.toString('utf-8').substring(0, 14) === "GET / HTTP/1.1") {
            this.securyPattern = /Sec-WebSocket-Key: (.*)/g;
            this.key = this.securyPattern.exec(buffer);
            this.magic = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
            this.sha1 = crypto.createHash("sha1");
            this.sha1.update(this.key[1] + this.magic);
            this.accept = this.sha1.digest("base64");
            socket.write("HTTP/1.1 101 Switching Protocols\r\nUpgrade: WebSocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: " + this.accept + "\r\n\r\n");
        } else {
            console.log(buffer);
            console.log(buffer.toString('utf-8'));
        }
    });

    socket.on('end', function() {
        users.splice(users.indexOf(socket), 1);
    });
}).listen(1337);

Everything works fine as it connects, and users.length is updated when that happens and when someone disconnects.

The problem is that I dont know how to read messages except the header (which is plain text), so the lines that I have to print the buffer and buffer.toString(‘utf-8’) only prints something binary different all the time, example for the word “hello”:

<Buffer 81 85 71 dc c1 02 19 b9 ad 6e 1e>
??q??☻↓??n▲
<Buffer 81 85 8e 8f 0f a2 e6 ea 63 ce e1>
????☼???c??

I’m sending this “hello” with Chrome 16 using:
myWebSocket.send(“hello”); where myWebSocket is the WebSocket object.

So how do I read and write messages to the socket with this?

Answer 1

Note that after the handshake, the data is framed with 2 or more header bytes at the beginning of each frame. Also, note that payload sent from the client (browser) to the server is masked using a simple 4-byte running XOR mask.

The framing definition is defined in section 5 of the spec

Instead of implementing your own WebSocket server in Node you might consider using a higher level abstraction like Socket.IO.