Pass query params from node.js server to socket.io

I'm writing a node.js app, that can generate url's like this:

http://examle.com/?param1=val&param2=val

I wonder if users will follow this urls to my app - is this possible to get params from this url and pass it to socket.io socket object that represents connection with user that was brought to site by that url.
I.E.:
    user followed this url;
    node.js express server handles that url and get the query params from it;
    Now I want to pass these params back to user but with socket.io emit(), not to whole sockets but only to user that was brought by url.

Is this goal achivable?
Should I use some id that will be passed with url and along socket.io handshake process and than store socket in array with id as key, to get this socket later in get request of express server?