IPN侦听器忽略cookie

your help needed! Everything works without any problem, but IPN listener ignores cookies ( $_COOKIE variable is empty)

my code :

file_put_contents("cookies_log.txt",print_r($_COOKIE, TRUE));   

ini_set('log_errors', true);
ini_set('error_log', dirname(__FILE__).'/ipn_errors.log');

// intantiate the IPN listener
include('ipn/ipnlistener.php');
$listener = new IpnListener();

//$listener->use_sandbox = true;
//$listener->use_curl = false; 
try {
 $listener->requirePostMethod();
 $verified = $listener->processIpn();
} catch (Exception $e) {
 error_log($e->getMessage());
 exit(o);
}

first line generetes cookies_log.txt file and in it is only:

Array
(
)

it means it didn't find cookies

PayPal's IPN system is a callback system only. This means the PayPal server is only going to send you a POST request. Even if you set a cookie when it did this, I seriously doubt the IPN system would retain it, let alone pass it back.

I would always expect the cookie list to be empty on a PayPal callback.