Untitled

How can I check if a user is already logged in? (everyauth, node.js)
var express = require('express')
, everyauth = require('everyauth')
, app = express.createServer();
everyauth.helpExpress(app);

everyauth.loggedIn

var userlogin = function () {
       var req = this.request
          ,res = this.response
          ,login = req.body
          ,username = login.username
          ,password = login.password;

      if(username === 'tester' && password === '12345'){
         req.session.user_id = xxxxxx;
         res.redirect('/');
      }else{
        res.redirect('/login');
      }

    }
    var checkAuth = function(fn_auth, fn_unauth){
      var req = this.request
          ,res = this.response
          ,unauthCallback;

      if(req.session.user_id){
        fn_auth(); //execute fn_auth if user is logged in. callback can be set to redirect to root path '/'
      }else{
          fn_unauth(); //execute fn_unauth calback which bring user to login path '/login'
        }
      }
    }