PHP redirect based on IP AND referrer - php

Question

I'm trying to redirect users within my network to a specific landing page on our website based on their IP and a blank referrer. This code works, but it ends up in a redirect loop. How do I break out of the redirect loop to correctly redirect a user? Thanks!
$visitor = $_SERVER['HTTP_REFERER'];
$clientip = $_SERVER['REMOTE_ADDR'];
$ip = a regex list of IPs;
if (empty($visitor))
{
if (preg_match($ip, $clientip)) {
header('Location: http://example.com');
die();
}
}

Answer 1

Add a session to that user that you know that they were redirected already:
session_start();
$visitor = $_SERVER['HTTP_REFERER'];
$clientip = $_SERVER['REMOTE_ADDR'];
$ip = a regex list of IPs;
if (empty($visitor))
{
//add on if they did not redirect yet.
if (preg_match($ip, $clientip) &&
(!isset($_SESSION['redirect']) || !$_SESSION['redirect'])) {
$_SESSION['redirect'] = true;
header('Location: http://example.com');
die();
}
}