How to detect multiple socket.io connections from same user
express, node.js, socket.io
Solution
In my application, I explicitly manage the socket.io sessions. On the server side, whenever a new connection is established, I do something like: `socketio_session[user_id].push(session)`. This gives me access to all the sessions connected for a particular user. In your case, you may not need to store a list of sessions per user, but only store the latest session and `onconnect` force disconnect on the existing session, if any, before storing the new session.
Problem
I have followed this guide: http://www.danielbaulig.de/socket-ioexpress/ to link express.js to socket.io and it works brilliantly. I have the user logging in on one page (express.js POST request that sets a session object) and when they have authenticated it directs them to a new page where socket.io loads and on the server socket.io can grab the session that was set from express. So that all works fine. Now I have users on the page that uses socket.io and when that page is refreshed - sometimes the socket.io connection is still there (ie. it doesn't disconnect). What I am trying to do is alter the `io.set('authorization')` function to ensure that when the user connects - it will disconnect all existing socket.io instances that are still open to that client. Here is the how it looks at the moment: ``` //socket.io connect to express var parseCookie = require('connect').utils.parseCookie; io.set('authorization', function (data, accept) { if (data.headers.cookie) { data.cookie = parseCookie(data.headers.cookie); data.sessionID = data.cookie['express.sid']; // (literally) get the session data from the session store sessionStore.get(data.sessionID, function (err, session) { if (err || !session) { // if we cannot grab a session, turn down the connection //note: a session is created when the user logs in accept('Error', false); } else { //TODO something here before we accept the connection //?? // save the session data data.session = session; //accept the connection accept(null, true); } }); } else { return accept('No cookie transmitted.', false); } }); ``` How do I check if the client that is about to be accepted has a previous connection, and it is still open (and therefore we need to disconnect that old one). The express session has a "username" in it - so we can get the session object and get the username, I just can't figure out how to go through the list of all the socket.io clients and have a look at the express session for each one and check if it the same as the user authenticating currently.