get the parent url of iframe in PHP

Question

I am creating a widget that would load in a IFrame and users will be able to place the widget on their own website. How would I get the URL of the website that is using the

Answer 1

I would use:

$qStr = explode('?', $_SERVER['HTTP_REFERER']);        
$t= explode('&', $qStr[1]);
foreach ($t as $val)
{
    $a = explode('=', $val);
    $args[$a[0]]=$a[1];
}
// to check the arguments
print_r($args);
// to check the url
echo $qStr[0];

$args would contain my security token which would be checked by some hashing against the url