socket.io connect to unix socket

Question

I want to connect to unix socket using socket.io-client, No success (mostly timeout, last sample - dns resolution error).

var clientio  = require('socket.io-client');
// i tried all variants here
//client=clientio.connect('port.io/',{'force new connection': true});
//client=clientio.connect('unix://port.io/',{'force new connection': true});
//client=clientio.connect('http//unix:port.io/',{'force new connection': true});

client.on('connect',connect);

Is there any way to connect socket.io client to unix socket ?

I checked server socket using nc -U port.io, it works fine.

Answer 1

sure we can do it.

client side (in node 8.11, not in browser):

var pipe_name = '/tmp/your-pipe-name';
var channel_name = '/your-namespace';
var server_url = "ws+unix://" + pipe_name + channel_name;

var path = require('path');
var url = require('url');
var WebSocket = require('ws');
var mock = require('mock-require');

class WebSockeMock extends WebSocket {
  constructor (address, protocols, options) {
    var uri = url.parse(server_url);
    var param = url.parse(address).search;
    address = "ws+unix:///" + uri.host + path.dirname(uri.pathname)
      + ":/socket.io/" + param;
    console.log("real ws", address)
    super(address, protocols, options);
  }
}

console.log("connecting to " + server_url);

if (/unix:\/+/.test(server_url)) {
  server_url = server_url.replace(/^[^:]+[:\/\\]+/, 'ws://');
  console.log("fake ws", server_url);
  mock('ws', WebSockeMock);
  process.env.DEBUG = '*';
}

var socket = require('socket.io-client')(server_url, {
  transports: ['websocket']
});

socket.on('connect', function() {
  return console.log("pipe connected");
});

server side:

var pipe_name = '/tmp/your-pipe-name';
var channel_name = '/your-namespace';

var fs = require('fs');
var path = require('path');

if (fs.existsSync(pipe_name)) {
  fs.unlinkSync(pipe_name);
}
console.log("pipe server at " + pipe_name);
var io = require('socket.io')(require('http').createServer().listen(pipe_name));
var channel = io.of("/" + (path.basename(pipe_name)) + channel_name)
.on('connection', function(socket) {
  console.log("unix pipe connected");
});

Answer 2

Just found this while looking for answers to similar question.

AFAIK socket.io-client depends on engne.io-client, which depends on ws, which contains this:

var isUnixSocket = serverUrl.protocol === 'ws+unix:';

See here: https://github.com/websockets/ws/blob/4f99812b1095979afaad58865846b160334f3415/lib/WebSocket.js#L598.

So it looks like it might be possible to connect client through UNIX socket, as long as it is done in node.js (or something similar) - i don't think it is possible to do in a web browser.

I did not try it, but maybe something like this will work:

var client=clientio.connect('ws+unix:/port.io',{'force new connection': true});

Update: it looks like socket.io and engine.io really do not like UNIX domain sockets :(. To connect through UDS, direct use of ws module seems to be the only way, but then it will not know all the additional stuff that socket.io builds on top (like rooms and namespaces).

Answer 3

Your question is vague, but since I came here looking for a similar answer, here is the code I came up with.

This code opens a unix domain socket, and broadcasts everything it receives to any connected socket.io clients (via WebSockets)

// Generated by CoffeeScript 1.9.2
var app, domain_server, fs, io, net, server;
fs = require('fs');
net = require('net');
app = require('express')();
server = require('http').Server(app);
io = require('socket.io')(server);

/* Handle Unix Domain Socket
 * * Delete file if it already exists, 
 *   avoiding EADDRINUSE  */

if (fs.existsSync('/tmp/domain_socket')) {
  fs.unlinkSync('/tmp/domain_socket');
}

domain_server = net.createServer(function(socket) {
  socket.on('data', function(data) {
    /* broadcast messages from unix socket to websockets */
    io.sockets.emit('domain-message', data.toString());
  });
});

domain_server.listen('/tmp/domain_socket', function() {
  console.log('domain_server bound');
});


/*
 * Handle Web Serving/WebSockets
 */

server.listen(8080);

app.get('/', function(req, res) {
  res.sendFile(__dirname + '/index.html');
});

io.on('connection', function(socket) {
  socket.emit('message', {
    hello: 'connected'
  });
});

Answer 4

socket.io runs a specific protocol on top of a webSocket protocol which then runs on a plain TCP socket. If you are trying to connect to a plain Unix socket, then you cannot use socket.io.

You can use net.Socket described here: http://nodejs.org/api/net.html which according to that doc is "is an abstraction of a TCP or UNIX socket".

A socket.io connection has a very specific startup protocol that it uses and a very specific over the wire data format and a very specific message sequence and a heatbeat keep-alive strategy. Both ends must support all of that for a socket.io connection to work.

A plain socket is the root transport at the lowest level, but all this other stuff must exist on top of that plain socket for the two sides to be able to talk to one another using socket.io. See this article if you want a concise overview of what is involved in writing a webSocket server. Socket.io is then another protocol on top of the webSocket transport.

---

Still very confused here. I have no idea why you mention a standard Unix socket.

If you're trying to connect from one nodejs server to another nodejs server using socket.io and one of the servers is running the default socket.io server that you showed in your comments, then you should be able to do this from the other one to connect to the socket.io server:

var socket = require('socket.io-client')('http://port.io');
socket.on('connect', function(){});
socket.on('event', function(data){});
socket.on('disconnect', function(){});

This assumes that port.io is the domain of your socket.io server (something that can be resolved with DNS to point to an actual server). It's important that what you use must be an actual HTTP URL because all webSocket and socket.io connections are initiated with an HTTP request to an actual HTTP URL.

I don't follow what you're trying to do with Unix URL schemes.