Cancel an HTTP POST request server side

Question

I am trying to write a script for uploading large files (>500MB). I would like to do some authentication before the upload is processed, eg:

$id = $_GET['key'];
$size = $_GET['size'];
$time = $_GET['time'];
$signature = $_GET['signature'];

$secret = 'asdfgh123456';

if(sha1($id.$size.$time.$secret) != $signature){
echo 'invalid signature';
exit;
}
process upload...

unfortunately php only runs this code after the file has been uploaded to a temp directory, taking up valuable server resources. Is there a way to do this before the upload happens? I have tried similar things with perl/cgi but the same thing happens.

Answer 1

Wow, already 5 answers telling how it can't be done. mod_perl to the rescue, here you can reject a request before the whole request body is uploaded.

Answer 2

Apache is taking care of the upload before the PHP script is even invoked so you won't be able to get at it.

You can either split up the process into two pages (authentication, file upload page) or, if you need to do it all in one page, use an AJAX-esque solution to upload the file after authentication parameters are checked.