Geekality

Simple PHP proxy for cross origin HEAD requests

Published:

Update 2017-02-06: Refactored this into a much more improved version, and you can find it on GitHub and Packagist.

Have some Javascript that runs through all the URLs on a site of mine to prep caching and check for dead links and other problems. Problem is that the site also includes embedded video files hosted by someone else. These fails of course because of cross origin restrictions and since I'm not in control of their servers I needed a workaround.

I wrote this small PHP script to work as a proxy and as far as I can see it works pretty great. Short and easy to follow as well, so that's always fun 🙂

So basically the script just pipes through whatever headers it gets to the target URL and pipes back whatever headers it gets in the response. Seems to work, but let me know of weaknesses and easy improvements if you see any 🙂

<?php

$request_headers = getallheaders();
unset($request_headers['Cookie']);
unset($request_headers['Host']);

foreach($request_headers as $key => &$value)
    $value = $key.': '.$value;

$url = $_SERVER['QUERY_STRING'];
$limit = 20;

$curl = curl_init();
do
{
    curl_setopt_array($curl, array
    (
        CURLOPT_URL => $url,
        CURLOPT_HTTPHEADER => $request_headers,

        CURLOPT_RETURNTRANSFER => TRUE,
        CURLOPT_HEADER => TRUE,
        CURLOPT_NOBODY => TRUE,

        CURLOPT_FOLLOWLOCATION => TRUE,
        CURLOPT_MAXREDIRS => $limit--,
    ));

    ob_start();
    $headers = trim(curl_exec($curl));
    $url = curl_getinfo($curl, CURLINFO_REDIRECT_URL);
    ob_end_clean();
}
while($url and $limit > 0);

curl_close($curl);

$headers = trim(substr($headers, strrpos($headers, "\r\n\r\n")));
header_remove();
foreach(explode("\r\n", $headers) as $h)
    header($h);

Notes