PHP gets real IP even if he uses proxy

[PHP] Code

function getRealIpAddr()
{
if (!empty($_SERVER['HTTP_CLIENT_IP']))
{
$ip=$_SERVER['HTTP_CLIENT_IP'];
}
elseif (!empty ($_SERVER['HTTP_X_FORWARDED_FOR']))
//Check the IP is passed from the proxy
{
$ip=$_SERVER['HTTP_X_FORWARDED_FOR'];
}
else
{
$ip=$_SERVER['REMOTE_ADDR'] ;
}
return $ip;
}

PHP