Comment récupérer l'url d'une page php ?

c'est un peu plus compliqué pour que ça marche à tous les coups (https, port, proxy), cf
https://github.com/Jasig/phpCAS/blob/1.3.1/source/CAS/Client.php#L3068
/**
* Try to figure out the server URL with possible Proxys / Ports etc.
*
* @return string Server URL with domain:port
*/
function _getServerUrl()
{
$server_url = '';
if (!empty($_SERVER['HTTP_X_FORWARDED_HOST'])) {
// explode the host list separated by comma and use the first host
$hosts = explode(',', $_SERVER['HTTP_X_FORWARDED_HOST']);
$server_url = $hosts[0];
} else if (!empty($_SERVER['HTTP_X_FORWARDED_SERVER'])) {
$server_url = $_SERVER['HTTP_X_FORWARDED_SERVER'];
} else {
if (empty($_SERVER['SERVER_NAME'])) {
$server_url = $_SERVER['HTTP_HOST'];
} else {
$server_url = $_SERVER['SERVER_NAME'];
}
}
if (!strpos($server_url, ':')) {
if ( ($this->_isHttps() && $_SERVER['SERVER_PORT']!=443)
|| (!$this->_isHttps() && $_SERVER['SERVER_PORT']!=80)
) {
$server_url .= ':';
$server_url .= $_SERVER['SERVER_PORT'];
}
}
return $server_url;
}