Zend Framework Active Directory authentication

Question

I have received applications written in Zend Framework 1.0.1. User authentication was reportedly taken using Active Directory. Now, to get into the application I used to workaround giving domain and user name: DPCAuthAdapter.php file

public function __construct(Zend_Db_Adapter_Abstract $db, $userlogin = null) {

    $this->_db=$db;

    $userlogin = 'PFD\\User2'; 

    if((null !== $userlogin) && (strpos($userlogin,'\\') > 0)) {
        list($this->_domain,$this->_username) = explode('\\',strtolower($userlogin),2);
    }
}

Without this application does not start. I have never used the domain user authentication. Please, tips on how I can do it, what to do, how to approach it.