Authenticating socket io connections using JWT

Question

How can I authenticate a socket.io connection? My application uses a login endpoint from another server (python) to get a token, how can I get use that token whenever a user opens a socket connection on the node side?

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

And the client side:

var token = sessionStorage.token;
var socket = io.connect('http://localhost:3000', {
    query: 'token=' + token
});

If the token is created in python:

token = jwt.encode(payload, SECRET_KEY, algorithm='HS256')

How can I use this token to authenticate a socket connection in node?

Answer 1

It doesn't matter if the token was created on another server. You can still verify it if you have the right secret key and algorithm.

Implementation with jsonwebtoken module

client

const {token} = sessionStorage;
const socket = io.connect('http://localhost:3000', {
  query: {token}
});

Server

const io = require('socket.io')();
const jwt = require('jsonwebtoken');

io.use(function(socket, next){
  if (socket.handshake.query && socket.handshake.query.token){
    jwt.verify(socket.handshake.query.token, 'SECRET_KEY', function(err, decoded) {
      if (err) return next(new Error('Authentication error'));
      socket.decoded = decoded;
      next();
    });
  }
  else {
    next(new Error('Authentication error'));
  }    
})
.on('connection', function(socket) {
    // Connection now authenticated to receive further events

    socket.on('message', function(message) {
        io.emit('message', message);
    });
});

Implementation with socketio-jwt module

This module makes the authentication much easier in both client and server side. Just check out their examples.

client

const {token} = sessionStorage;
const socket = io.connect('http://localhost:3000');
socket.on('connect', function (socket) {
  socket
    .on('authenticated', function () {
      //do other things
    })
    .emit('authenticate', {token}); //send the jwt
});

Server

const io = require('socket.io')();
const socketioJwt = require('socketio-jwt');

io.sockets
  .on('connection', socketioJwt.authorize({
    secret: 'SECRET_KEY',
    timeout: 15000 // 15 seconds to send the authentication message
  })).on('authenticated', function(socket) {
    //this socket is authenticated, we are good to handle more events from it.
    console.log(`Hello! ${socket.decoded_token.name}`);
  });

Answer 2

Since I don't have enough reputation to add a comment to accepted answer:

const socketioJwt = require('socketio-jwt');

Is not actually apart of auth0 's repo and is a third-party community based package.

Answer above should be updated as the link to auth0 repo is a page 404.

Answer 3

Write a middleware:

const jwt = require("jsonwebtoken");

const authSocketMiddleware = (socket, next) => {
  // since you are sending the token with the query
  const token = socket.handshake.query?.token;
  try {
    const decoded = jwt.verify(token, process.env.TOKEN_SECRET_KEY);
    socket.user = decoded;
  } catch (err) {
    return next(new Error("NOT AUTHORIZED"));
  }
  next();
};

module.exports = authSocketMiddleware;

Use it inside socket server

socketServer = (server) => {
  const io = require("socket.io")(server, {
    cors: {
      origin: "*",
      methods: ["GET", "POST"],
    },
  });
  // before connection use the middleware
  io.use((socket, next) => {
    authSocketMiddleware(socket, next);
  });
  io.on("connection", (socket) => {
    console.log("user connected", socket.id);
  });
};

Answer 4

Here I wrote the indepth article on how to authenticate the user on the sockets and also save the user's data

https://medium.com/@tameemrafay/how-to-authenticate-user-and-store-the-data-in-sockets-19b262496feb

CLIENT SIDE CODE

import io from "socket.io-client";

const SERVER = "localhost:4000";
const socket = io(SERVER, {
    auth: {
      token: "2c87b3d5412551ad69aet757f81f6a73eb919e5b02467aed419f5b2a9cce2b5aZOzgaM+bpKfjdM9jvez37RTEemAp07kOvEFJ3pBzvj8="
    }
  });

 socket.once('connect', (socketConnection) => {
    console.log('socket connected', socketConnection);
  })
 
// Emit the message and receive data from server in callback
 socket.emit("user send message", {message: "Hi you there" }, callback => {
    if (callback) {
      console.log("--- response from server", callback);
     }
  });

SERVER SIDE CODE

const initializeSockets = (io) => {
  io.on('connection', (socket) => {

  decryptAndStoreUserData(socket,io);
  
}

const decryptAndStoreUserData = async (socket,io) => {

    const { token } = socket.handshake.auth; // receive the token from client

    // here i decypt the auth token and get the user data
    const genToken = new Middlewares().token();
    const userData = genToken.decryptTokenForSockets(token);

    // save the data of user in socket
    socket.data.user = userData;

  }