socket.io authentication after socket established

This isn't actually too hard, but you're approaching it the wrong way. A couple things:

1. You cannot set a cookie with socket.io; you can, however, get the cookie values of any connected client at any time. In order to set a cookie, you will have to send a new http response, meaning the user must first send a new http request (aka refresh or go to a new page, which it sounds is not a possibility for you here).

2. Yes: socket.io is secure (to the extent that any transmitted data can be).

As such, you can do the following:

On the user's initial connection, create a cookie with a unique session ID, such as those generated from Express's session middleware. You will need to configure these not to expire on session end though (otherwise it will expire as soon as they close their browser).

Next you should create an object to store the cookie session IDs. Each time a new connect.sid cookie is set, store in your new object with a default value of false (meaning that the user has been authenticated by session, but not by logon)

On the user's login, send a socket emit to the server, where you can then authenticate the login credentials, and subsequently update the session id object you created to read true (logged in) for the current socket id.

Now, when receiving a new http request, read the cookie.sid, and check if its value in your object is true.

It should look something like the following:

var express = require('express'),
http = require('http'),
cookie = require('cookie');

var app = express();
var server = http.createServer(app);
var io = require('socket.io').listen(server);


app.use(express.cookieParser());
app.use(express.session({ 
    secret: 'secret_pw',
    store: sessionStore,
    cookie: { 
        secure: true,
        expires: new Date(Date.now() + 60 * 1000), //setting cookie to not expire on session end
        maxAge: 60 * 1000,
        key: 'connect.sid'
    }
}));

var sessionobj = {}; //This is important; it will contain your connect.sid IDs.

//io.set('authorization'...etc. here to authorize socket connection and ensure legitimacy


app.get("/*", function(req, res, next){
    if(sessionobj[req.cookies['connect.sid']]){
        if(sessionobj[req.cookies['connect.sid']].login == true){
            //Authenticated AND Logged in
        }
        else{
            //authenticated but not logged in
        }
    }
    else{
        //not authenticated
    }

});


io.sockets.on('connection', function(socket){
    sessionobj[cookie.parse(socket.handshake.headers.cookie)['connect.sid'].login = false;
    sessionobj[cookie.parse(socket.handshake.headers.cookie)['connect.sid'].socketid = socket.id;

    socket.on('login', function(data){
        //DB Call, where you authenticate login
        //on callback (if login is successful):
        sessionobj[cookie.parse(socket.handshake.headers.cookie)['connect.sid']] = true;
    });

    socket.on('disconnect', function(data){
        //any cleanup actions you may want
    });

});

Chris, I'm won't be able to answer since I'm not an expert on socket.io, but I can maybe try to point you in another direction that can help you - and take away some development time.

But first, a disclaimer: I work for Realtime.co and am not trying to do any sort of advertising. I work closely with developers and I'm just trying to help you by providing you an out-of-the-box solution for your problem. Also, being a gamer, I can't stay away from trying to help people getting their games out there!

Realtime uses an authentication/authorization layer in which you can provide user read/write permissions to channels. When users enters the website you can give them read only permissions to the game channel and once they login, you can then give them write permissions. This can be easily done by doing an authentication post and reconnecting to the server (it can all be done client side). I would do it server-side, though, to increase security.

Realtime has a Node.js API so you can easily integrate it with your server. Since it also has APIs for many other platforms (including mobile) and they all work the same way, you can actually have your game working in multiple platforms over the same communication layer, while having full control over channels.

Thanks for reading.

Edit:

You can read the documentation here for more info: http://docs.xrtml.org/