PHP + socket.io (session, authorizing and security problems)

Question

I have a working php application in which I want to add real-time support. I would like to use nodejs/socket.io to add that kind of functionality.

First problem I found was how to properly authorize user on nodejs side (user is already authenticated on php backend through PHP session). Using socket.handshake.header.cookie on nodejs side i can parse and get PHP session id, which I can authenticate through redis/memcache/database (depending on what have I used to save session information).
Everything looks cool when user has only one tab/window of the site opened - when having more and using session_regenerate_id(), in nodejs the user authenticates with another sessionid key, so I cannot distinguish two tabs by anything other than the socket id they connected with. When user logouts he shouldn't be getting any messages on any tab (because he already logged out on every tab/window from that browser). So on logout message (sent from browser just before the logout PHP things) I should remove all the socket connections connected to the authorized user id. But what if user logges in on two devices (fe. pc browser and an ipad safaris). After logout on one device, he shouldn't be getting any messages on the device he logged out, not on every device. How can i distinguish connections from different devices/browsers in socket.io? Of course not using session_regenerate_id() would be efficent here, but what can I do if I really want to use this feature?

Another problem I have is rather a security issue (or even question). Let's assume that authorized user in application can see page example.com/user1 (which is a news feed for user1) and cannot see example.com/user2 (fe. he doesn't have rights to see it). I'd like socket.io to send update messages to browser when user is on example.com/user1, and of course not to send when user is on example.com/user2 site. On socket.io side I can read the referer address (so presumably, when user is on user2 site he does not get any socket.io connection). The question is: should I compare the referer address with the rights of authenticated user on node.js side? Or maybe the referer value is safe on the node.js side? Adding another db check on node.js side would slow it down (because almost every request there should be same database check on two sides - PHP and node.js).

Or maybe the whole concept of socket.io + PHP application working the way I presented is wrong?

UPDATE

I think I found a way to omit problems with the first question - basically I just add another cookie (besides PHPSESSID) fe. named NODESESSID, which I generate (fe. using uniqid()) when user is authorized. Now authorization on node.js side is comparing PHPSESSID and NODESESSID (both must match). Now, when user logges out he delivers the message logout to socket.io and socket.io disconnects all the sockets with NODESESSID. This is like connecting the benefits of regenerating session id and not regenerating session id (but is not vulnerable to session fixation, isn't it?).

Answer 1

For your second questions:

the Referer is not secure, as mentioned in the comments.

I hava a similar problem in my application and this is how it works for me.

first, i hava a single-page app where all traffic goes through the socket, but thats not necessary. it should work with sessions the way you managed it, too.

in nodejs onConnect I ask the backend if the user is authenticated and then store the userid into the socket object (socket.data) and also populate a hashmap to lookup sockets from userids directly.

second, i use Redis and subscribe to a redis list from nodejs (see redis pub/sub). the php backend pushes messages in this list with a userid to address the message. nodejs takes this message (e.g. a new news feed item), looks up the userid in the mentioned hashmap and sends it to the client. so, a user only gets what he is authorized for. the client then decides what to do with the message. if the user is on his feed page, it could add the item. if the user is on someone elses feed, it could simply add a notification somewhere else on the page. it might also discard it.

on the php backend site, this messages are send to redis everytime an event occurs which needs to be shown live on some connected client. if user1 posts on user2's feed, the new item is stored in the database and in the same time is send as message into the redis queue.

this system also helps to reduce DB load since nodejs just need to query a database to make sure the connected user is already authenticated.