As a lot of comments have pointed out below the Socket.IO API changed in their 1.0 release. Authentication should now be done via a middleware function, see 'Authentication differences' @ http://socket.io/docs/migrating-from-0-9/#authentication-differences. I'll include my orginal answer for anyone stuck on <1.0 as the old docs seem to be gone.
1.0 and later:
Client Side:
//The query member of the options object is passed to the server on connection and parsed as a CGI style Querystring.
var socket = io("http://127.0.0.1:3000/", { query: "foo=bar" });
Server Side:
io.use(function(socket, next){
console.log("Query: ", socket.handshake.query);
// return the result of next() to accept the connection.
if (socket.handshake.query.foo == "bar") {
return next();
}
// call next() with an Error if you need to reject the connection.
next(new Error('Authentication error'));
});
Pre 1.0
You can pass a query: param in the second argument to connect() on the client side which will be available on the server in the authorization method.
I've just been testing it. On the client I have:
var c = io.connect('http://127.0.0.1:3000/', { query: "foo=bar" });
On the server:
io.set('authorization', function (handshakeData, cb) {
console.log('Auth: ', handshakeData.query);
cb(null, true);
});
The output on the server then looked like:
:!node node_app/main.js
info - socket.io started
Auth: { foo: 'bar', t: '1355859917678' }
Update
3.x and later
You can pass an authentication payload using the auth param as the second argument to connect() in the client side.
Client Side:
io.connect("http://127.0.0.1:3000/", {
auth: {
token: "AuthToken",
},
}),
In server side you can access it using socket.handshake.auth.token
Server Side:
io.use(function(socket, next){
console.log(socket.handshake.auth.token)
next()
});
