filter requests by domain

[smile]

hello, I have this php script on" domain22.com" that processes the requests:

 

mysa_output.php

<?php
$mysa_ipaddress = strip_tags($_GET['r']);
if(strip_tags(urldecode($_GET['h']))!='') $mysa_hostname = strip_tags(urldecode($_GET['h']));
if(strip_tags(urldecode($_GET['rf']))!='') $mysa_referer = strip_tags(urldecode($_GET['rf']));
$mysa_show_ad_group = strip_tags($_GET['show_ad_group']);
$mysa_show_ad = strip_tags($_GET['show_ad']);
if (is_numeric($mysa_show_ad_group)){
    include_once("mysimpleads.php");show_ad_group($mysa_show_ad_group);
} else if (is_numeric($mysa_show_ad)){
    include_once("mysimpleads.php");show_ad($mysa_show_ad);
} else {
    exit;
}
?>

 

Then I have code that I put on some other domain33.com that connects to this script to pull data

<?php @readfile('http://domain22.com/mysa_output.php?r='.$_SERVER['REMOTE_ADDR'].'&h='.urlencode($_SERVER['HTTP_HOST']).'&rf='.urlencode($_SERVER['HTTP_REFERER']).'&show_ad=2'); ?> 

My problem is that I need to filter and allow the domain33.com and "&show_ad=2" so that from domain33.com you can't view others ID ads like "&show_ad=5" "&show_ad=10" etc.

 

There would be multiple domains, and ID's. Simple cycle check would work fine.

 

I need to put some code into the mysa_output.php

Thank you.