connect-session-in-socket-io.js

// helper function that goes inside your socket connection
client.connectSession = function(fn) {
  var cookie = client.request.headers.cookie;
  var sid = unescape(cookie.match(/connect\.sid=([^;]+)/)[1]);
  redis.get(sid, function(err, data) {
    fn(err, JSON.parse(data));
  });
};

// usage
client.connectSession(function(err, data) {
  console.log(data);
});