vBSSO / Shared Login

[AnthonyTang]

Hello,

I am currently running vBulletin 4.2.0 PL3 and I'm currently developing a portal page for my community. On the main page, I would like to simply connect to the database and check if they are currently logged in on the forums or not. It would simply display "Welcome, $username." on the portal navigation if their login is true. If not, it would just display two input boxes for them to log into.

The problem I am running into is:
- I don't know what API/Code I should be using to fetch this data
- If they aren't logged in, and I would like them to be able to via the portal page, how would I do so with the current password encryption to the string?

I've tried using the method where I require_once('./global.php'); at the top of my portal and then use this code:

<? require_once('./forum/global.php');
if ($vbulletin->userinfo['userid'] == 0) 
{
    echo 'Input boxes/login';
}
else
{
    echo 'Welcome back, {username}';
}
?>

Though with the code I posted above, I get these errors:

[15-Jan-2013 07:17:41 UTC] PHP Warning:  require_once(./includes/class_bootstrap.php) [<a href='function.require-once'>function.require-once</a>]: failed to open stream: No such file or directory in /home/<USERNAME>/public_html/forum/global.php on line 15
[15-Jan-2013 07:17:41 UTC] PHP Fatal error:  require_once() [<a href='function.require'>function.require</a>]: Failed opening required './includes/class_bootstrap.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/<USERNAME>/public_html/forum/global.php on line 15

Thank you very much,
Anthony

P.S. I've already looked into addons such as this. Unfortunately it only supports 'official' 3rd party platforms such as WordPress or Mediawiki.