title: How to access codeigniter session variable from external site
body: <p>I've trying to add a messageboard to my Codeigniter web site.  Everything has gone well except for one little part: I'd like my log in from the main site to carry over to the messageboard.  Since the messageboard is not able to run in Codeigniter, I made a subdomain to run the messageboard in.  This means that the main site and the messageboard do not share cookies.  The messageboard is Phorum-powered, so there's a hook that I can use to sign in if I have the user_id of my user.  In other words my problem basically boils down to being able to run a function on one domain that can get the user_id variable stored in the session of another domain.</p>
  
  <p>Here are things the I've tried:</p>
  
  <ol>
  <li><p>Setting up a controller in codeigniter that uses ci->session to echo the user_id.  Then in the messageboard, I used CURL to fetch me the output of the codeigniter controller.  This doesn't seem to work because CURL doesn't carry cookies or sessions or something, so codeigniter can't access it's session when called through CURL.</p></li>
  <li><p>Same thing but with file_get_contents.  File_get_contents is disabled on my server.</p></li>
  </ol>
  
  <p>I'm pretty much out of ideas.  Does anyone know a function I could write that would get me a CI session stored user_id from a different domain?</p>