Websocket handshake Error between Node.js and React

Question

I'm writing a application using sockets, but can't seem to get the initial handshake to work. I'm using WebSockets + React on my front-end, running on PORT 8080, and Node.js socket on the backend running on PORT 5000. The front-end handshake is done through my component like so:

    componentDidMount(){
        this.socket = new WebSocket('ws://localhost:5000', ['json']);
        this.socket.onerror = err => {
            console.log(err)
        }
        this.socket.onmessage = e => {
            let res = JSON.parse(e.data);
            console.log(e, res);
            let copyArr = [...this.state.message]
            copyArr.push(res);

            this.setState({
                message: copyArr
            });
        }
    }

On my Node server, I do:

const server = http.createServer();

server.on('upgrade', (req, socket) => {

    if(req.headers['upgrade'] !== "websocket"){
        socket.end('HTTP/1.1 400 Bad Request');
        return;
    }

    const acceptKey = req.headers['sec-websocket-key'];
    const acceptHash = generateValue(acceptKey);

    console.log('accepkey', acceptKey, 'hash', acceptHash);

    const resHeaders = [ 'HTTP/1.1 101 Web Socket Protocol Handshake', 'Upgrade: WebSocket', 'Connection: Upgrade', `Sec-WebSocket-Accept: ${acceptHash}` ];

    console.log(resHeaders);

    let protocols = req.headers['sec-websocket-protocol'];
    protocols = !protocols ? [] : protocols.split(',').map(name => name.trim());

    if(protocols.includes('json')){
        console.log('json here');
        resHeaders.push(`Sec-WebSocket-Protocol: json`);
    }

    socket.write(resHeaders.join('\r\n') + '\r\n\r\n');
})

function generateValue(key){
    return crypto
      .createHash('sha1')
      .update(key + '258EAFA5-E914–47DA-95CA-C5AB0DC85B11', 'binary')
      .digest('base64');
}

When my React component mounts, it tries to establish the initial handshake but fails with the error: WebSocket connection to 'ws://localhost:5000/' failed: Error during WebSocket handshake: Incorrect 'Sec-WebSocket-Accept' header value. I've checked using Chrome developer tool and found this While on the backend, when logging the request accept-key header, and response headers, I saw this:

So, unless I'm mistaken about these headers, it seems that the request and response accept-key header somehow changes when making it's way from the client to the server, and vice versa. How is this happening? Or have I misunderstood what's going on. Why exactly is the initial handshake not working?

In your screenshot you're looking not at your websocket request. Look at the URL, this is webpack-dev-server websocket connection (localhost:8080) which were successful (status code 101) — GProst
– GProst, Commented Mar 31, 2019 at 15:44

Forhad · Accepted Answer · 2019-09-29 18:53:12Z

1

There is a en dash – instead of hyphen - in 258EAFA5-E914–47DA-95CA-C5AB0DC85B11 after E914 So replace it with hyphen -

reference https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Sec-WebSocket-Accept

answered Sep 29, 2019 at 18:53

Forhad

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GProst · Accepted Answer · 2019-03-31 16:02:21Z

0

I believe the generateValue function is wrong, you pass binary as the inputData encoding which is a keyword for latin1 according to the docs. But I believe it is UTF-8 string, not latin1, so the result hash is wrong. So just try to use update(key + '258EAFA5-E914–47DA-95CA-C5AB0DC85B11', 'utf8') or even without the second utf8 argument since it is a default.

answered Mar 31, 2019 at 16:02

GProst

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