PHP file_get_contents and VAST xml - php

Question

This is what am I trying to do: download a xml VAST from a URL and save locally in a XML file, in PHP. For that I am using file_get_contents and file_put_contents. this is the script I am using:
<?php
$tid=time();
$xml1 = file_get_contents('http://ad.afy11.net/ad?enc=4&asId=1000009566807&sf=0&ct=256');
file_put_contents("downloads/file1_$tid.xml", $xml1);
echo "<p>file 1 recorded</p>";
?>
The URL in question is a real URL that will deliver a xml VAST code. My problem is that when I save de file it will write an empty VAST tag:
<?xml version="1.0" encoding="UTF-8"?> <VAST version="2.0"> </VAST>
But if I run on Firefox it will actually deliver some code:
<VAST version="2.0"><Ad id="Adify"><Wrapper><AdSystem>Eyeblaster</AdSystem><VASTAdTagURI>http://bs.serving-sys.com/BurstingPipe/adServer.bs?cn=is&c=23&pl=VAST&pli=6583370&PluID=0&pos=7070&ord=4288438534]&cim=1</VASTAdTagURI><Impression>http://ad.afy11.net/ad?ipc=NMUsqYdyBUCjh4-i2HwWfK1oILM2AAAAN6-rBkSy8JNMZcuzAlj1XlSySpo6Hi7xEYULS+UgOVN5D3UuhFUVSWbFHoLE-+3su0-QnGgZgMJyiTm-R6O+yQ==</Impression><Creatives/></Wrapper></Ad></VAST>
Not a 100% of the time, they do cap the amount of requests, but WAY more often that when I try save the file using the PHP script.
Is that a way to make the PHP script mimic a browser???? I dont know if this is the right question but thats the only thing I can think of why I get an empty VAST tag when using the php script and get a full tag when using the browser.
any ideas???
thanks :)
Update: After doing some extra research, I found some info about stream_context_create function, but I haven't been able to duplicate the browser's results.
here's my new code:
<?php
$tid=time();
$opts = array('http' =>
array(
'method' => 'GET',
//'user_agent ' => "Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2) Gecko/20100301 Ubuntu/9.10 (karmic) Firefox/3.6",
'header' => array(
'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*\/*;q=0.8
'
),
)
);
$context = stream_context_create($opts);
$xml1 = file_get_contents('http://ad.afy11.net/ad?enc=4&asId=1000009566807&sf=0&ct=256');
file_put_contents("downloads/file1_$tid.xml", $xml1);
echo "<p>file 1 recorded</p>";
echo "<textarea rows='6' cols='80'> $xml1 </textarea> ";
echo "<br><iframe src='http://ad.afy11.net/ad?enc=4&asId=1000009566807&sf=0&ct=256' width='960' height='300'></iframe>";
?>
I also addded a iframe to compare when the browser are getting the right file and when the php function are not.

Answer 1

After some research I found a solution for my problem, and I would like to share here for future reference.
The idea as to pass some HTTP header with the file_get_contents. I accomplish that with this:
$opts = array(
'http'=>array(
'method'=>"GET",
'header'=>array("Accept-language: en", "Content-Type: multipart/form-data\r\n"),
'user_agent'=> $_SERVER['HTTP_USER_AGENT']
)
);
$context = stream_context_create($opts);
$xml4 = file_get_contents($url1, true, $context);
That's it, now I can get the same xml as if I was using the browser.