รบกวนหน่อยนะครับท่านใดเคยทำlogin เข้าเว็บด้วยfacebook บ้างขอคำชี้แนะหน่อยครับ

<?
protected function getCode() {
    if (isset($_REQUEST['code'])) {
      if ($this->state !== null && isset($_REQUEST['state']) && $this->state == $_REQUEST['state']) {

        // CSRF state has done its job, so clear it
        $this->state = null;
        $this->clearPersistentData('state');
        return $_REQUEST['code'];
      } else {
		 $add = '';
		 if($this->state == null){
            $add .= ' state is null.';
        }
        if(!isset($_REQUEST['state'])){
            $add .= ' state is not set.';
        }
        if($this->state !== $_REQUEST['state']){
            $add .= ' states do not match.';
        }
        self::errorLog('CSRF state token does not match one provided.');
        return false;
      }
    }

    return false;
  }

?>