Serving file hosted on another server as download

Question

I have a simple, yet critical question (critical for my application)

I will have a file url as:

http://a.com/b.jpg
http://a.com/b.zip
http://a.com/b.         


        

Answer 1

1. store file outside web root
2. filesize(filename) will get the file size
3. as your forcing download you don't need to know the mime type

Answer 2

I suppose you can use cURL to fire off a HEAD request for the target URL. This will let the web server hosting the target the mimetype and content length of the file.

$url = 'http://www.example.com/path/somefile.ext';
$ch = curl_init(); 
curl_setopt($ch, CURLOPT_HEADER, true); 
curl_setopt($ch, CURLOPT_NOBODY, true); // make it a HEAD request
curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true); 
curl_setopt($ch, CURLOPT_URL, $url); 
curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE); 
$head = curl_exec($ch);

$mimeType = curl_getinfo($ch, CURLINFO_CONTENT_TYPE);
$size = curl_getinfo($ch, CURLINFO_CONTENT_LENGTH_DOWNLOAD);
$path = parse_url($url, PHP_URL_PATH);
$filename = substr($path, strrpos($path, '/') + 1);

curl_close($ch); 

Then, you can write back these headers to the HTTP request made on your script:

header('Content-Type: '.$mimeType);
header('Content-Disposition: attachment; filename="'.$filename. '";' );
header('Content-Length: '.$size);

And then you follow this up with the file contents.

readfile($url);