Facebook应用程序在Facebook页面内获取身份验证

I have a facebook page I have built an application to be in the page tab the application works fine with the original url it get the login from the facebook and return to the url

how i can get the authintication from the user without changing the url "inside the iframe" ?

require_once("facebook.php");
$facebook = new Facebook(array(
        'appId' => 'App_id',
        'secret' => 'Secret'));
$current_user = $facebook->getUser();

$params = array('scope' =>'email,user_likes,user_friends');
if ($current_user) { 
    try {
            $expiration = time() + 172800; 
            $cookie_value = $current_user . '|' . $expiration;
            setcookie('fbid', $cookie_value, $expiration , "/");
            echo '<script type="text/javascript">
            window.location = "like.php";
            </script>';
    } catch (FacebookApiException $e) {
        $login_url = $facebook->getLoginUrl($params);
        echo '<script type="text/javascript">
        window.location = "' . $login_url . '";
        </script>';
        exit;
        error_log($e->getType());
        error_log($e->getMessage());
    }
} else {
    $login_url = $facebook->getLoginUrl($params);
    echo '<script type="text/javascript">
        window.location = "'.$login_url.'";
        </script>';
    exit;
}

create a facebook tab application not web application and use JS SDK