Source for file login.act.php

<?php
/**
 * @since 7/21/05
 * @package polyphony.authentication
 * 
 * @copyright Copyright &copy; 2005, Middlebury College
 * @license http://www.gnu.org/copyleft/gpl.html GNU General Public License (GPL)
 *
 * @version $Id: login.act.php,v 1.16 2007/09/19 14:04:53 adamfranco Exp $
 */ 
 
require_once(POLYPHONY."/main/library/AbstractActions/Action.class.php");
 
/**
 * Change the language to the one specified by the user
 * 
 * @since 7/21/05
 * @package polyphony.language
 * 
 * @copyright Copyright &copy; 2005, Middlebury College
 * @license http://www.gnu.org/copyleft/gpl.html GNU General Public License (GPL)
 *
 * @version $Id: login.act.php,v 1.16 2007/09/19 14:04:53 adamfranco Exp $
 */
class loginAction
    extends Action
{
        
    /**
     * Check Authorizations
     * 
     * @return boolean 
     * @access public
     * @since 4/26/05
     */
    function isAuthorizedToExecute () {
        return TRUE;
    }
    
    /**
     * Execute this action.
     * 
     * @param object Harmoni $harmoni 
     * @return mixed 
     * @access public
     * @since 4/25/05
     */
    function execute ( $harmoni ) {
        $harmoni = Harmoni::instance();
        
        // If we are using only cookies, but cookies aren't enabled
        // (and hence not set), print an error message.
        if ($harmoni->config->get("sessionUseOnlyCookies")
            && !isset($_COOKIE[$harmoni->config->get("sessionName")]))
        {
            RequestContext::sendTo($harmoni->request->quickURL('auth', 'cookies_required'));
        }
 
        $isAuthenticated = FALSE;
        $authN = Services::getService("AuthN");
        
        // authenticate.
        $authTypes =$authN->getAuthenticationTypes();
        while ($authTypes->hasNext()) {
            $authType =$authTypes->next();
            
            // Try authenticating with this type
            $authN->authenticateUser($authType);
            
            // If they are authenticated, quit
            if ($authN->isUserAuthenticated($authType)) {
                $isAuthenticated = TRUE;
            }
        }
 
        if ($isAuthenticated) {
            // Send us back to where we want to be if we succeeded 
            // (usually where we were)
            $harmoni->history->goBack("polyphony/display_login");
        } else {
            // send us to where we want to be if we failed
            // (possibly some form of authentication viewer)
            $harmoni->history->goBack("polyphony/login_fail");
        }
        
        $null = null;
        return $null;
    }
}