Automatic Login to websites where form action = 'relative path'

[Lunatiko]

<?php
$username="user"; 
$password="pass"; 
$cookie="cookie.txt"; 
$url = 'http://www.affilate.mikkelsenmedia.dk/partnersystem/mylogins.php';
$postdata = "username=".$username."&password=".$password."&send=Submit"; 

$ch = curl_init(); 
curl_setopt ($ch, CURLOPT_URL, $url); 
curl_setopt ($ch, CURLOPT_SSL_VERIFYPEER, FALSE); 
curl_setopt ($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.6) Gecko/20070725 Firefox/2.0.0.6"); 
curl_setopt ($ch, CURLOPT_TIMEOUT, 60); 
curl_setopt ($ch, CURLOPT_FOLLOWLOCATION, 1); 
curl_setopt ($ch, CURLOPT_RETURNTRANSFER, 1); 
curl_setopt ($ch, CURLOPT_COOKIEJAR, $cookie); 
//curl_setopt ($ch, CURLOPT_REFERER, 'http://www.euroads.dk'); 
curl_setopt ($ch, CURLOPT_POSTFIELDS, $postdata); 
curl_setopt ($ch, CURLOPT_POST, 1); 
$result = curl_exec ($ch); 
curl_close($ch);

echo $result;
?>

I tried this code to automatically login to a website where form action is not an absolute path. Each time i try this code in the locally, it redirects me to the index of localhost. Maybe because the form action has a relative path. Question is, how would i be able to change the action from relative to absolute before actually submitting the form and before executing the curl session. Need immediate response. Thanks