Hi, I am trying to integrate some third party tracking code into one of my sites, however it is throwing up some errors, and their support isn't being much use, so i want to try and fix their code myself. Most I have fixed, however this function is giving me problems:

private function getXForwardedFor()
{
$s =& $this;

$xff_ips = array();

$headers = $s->getHTTPHeaders();

if ($headers['X-Forwarded-For']) {
$xff_ips[] = $headers['X-Forwarded-For'];
}

if ($_SERVER['REMOTE_ADDR']) {
$xff_ips[] = $_SERVER['REMOTE_ADDR'];
}

return implode(', ', $xff_ips); // will return blank if not on a web server
}

In my dev enviroment where I am showing all errors I am getting:

 Notice: Undefined index: X-Forwarded-For in /sites/webs/includes/OmnitureMeasurement.class.php  on line 1129

Line 1129 is:

if ($headers['X-Forwarded-For']) { 

If I print out $headers I get:

Array
(
[Host] => www.domain.com
[User-Agent] => Mozilla/5.0 (Windows; U; Windows NT 6.1; en-GB; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3
[Accept] => text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
[Accept-Language] => en-gb,en;q=0.5
[Accept-Encoding] => gzip,deflate
[Accept-Charset] => ISO-8859-1,utf-8;q=0.7,*;q=0.7
[Keep-Alive] => 115
[Connection] => keep-alive
[Referer] => http://www10.toptable.com/
[Cookie] => PHPSESSID=nh9jd1ianmr4jon2rr7lo0g553; __utmb=134653559.30.10.1275901644; __utmc=134653559
[Cache-Control] => max-age=0
)

I can't see X-Forwarded-For in there which I think is causing the problem. Is there something I should add to the function to take this into account?

I am using PHP 5.3 and Apache 2 on Fedora