generic websocket proxy

[philkunz]

Any reason why socket.io does not connect the websocket transport through the following websocket proxy?

import http from 'http'; // node default
import * as ws from 'ws'; // ws from npm
import wsDefault from 'ws'; // ws from npm
import * as smartpromise from '@pushrocks/smartpromise' // @pushrocks/smartpromise from npm

const wss = new ws.WebSocketServer();
wss.on('connection', (ws: wsDefault, reqArg: http.IncomingMessage) => {
  console.log(`wss: got connection for wsc for https://${reqArg.headers.host}${reqArg.url}`);
  let wscConnectedDeferred: smartpromise.Deferred<wsDefault>;

  ws.on('message', async (message) => {
    if (!wscConnectedDeferred) {
      wscConnectedDeferred = smartpromise.defer();
      let wsc: wsDefault;
      try {
        wsc = new wsDefault(`ws://[someip]:[someport]${reqArg.url}`, {
          headers: reqArg.headers
        });
      } catch (err) {
        console.log(err);
        ws.terminate();
        return;
      }
      wsc.on('open', () => {
        console.log('wsc opened.');
        wscConnectedDeferred.resolve(wsc);
      });
      wsc.on('message', (message) => {
        ws.send(message);
      });
    }
    const wsc = await wscConnectedDeferred.promise;
    wsc.send(message);
    // handle closing
    const cleanUp = () => {
      ws.terminate();
      wsc.terminate();
    };

    ws.on('close', (message) => {
      cleanUp();
    });

    wsc.on('close', (message) => {
      cleanUp();
    });
  });
});

[darrachequesne]

Here's a working WebSocket proxy:

import { WebSocketServer, default as WebSocket } from "ws";

const proxy = new WebSocketServer({
  port: 3001
});

proxy.on("connection", async (ws, reqArg) => {
  console.log(`wss: got connection for wsc for https://${reqArg.headers.host}${reqArg.url}`);

  let wsc;
  try {
    wsc = new WebSocket(`ws://localhost:3000${reqArg.url}`);
  } catch (err) {
    console.log(err);
    ws.terminate();
    return;
  }

  ws.on("message", (message, isBinary) => {
    console.log("client to upstream", message);
    wsc.send(message, { binary: isBinary });
  });

  wsc.on("message", (message, isBinary) => {
    console.log("upstream to client", message);
    ws.send(message, { binary: isBinary });
  });

  ws.on("close", () => wsc.terminate());
  wsc.on("close", () => ws.terminate());
});

Example: https://github.com/socketio/socket.io-fiddle/tree/issues/socket.io/4581

Reference: https://github.com/websockets/ws/blob/master/doc/ws.md#websocketsenddata-options-callback

[philkunz]

Thank you so much. This works perfectly.