Caching of files served by ReadFile(): headers not being sent?

[Vector]

I echoed apache_request_headers() and $_SERVER['HTTP_IF_MODIFIED_SINCE'], but the $_SERVER version is empty each time, and the apache_request_headers does not have the if-modified-since. I send these headers on the initial download, and if you click download again, there is no caching or last-modified. I also used tamper-data to watch the headers being sent (and received), and when the server is sending the headers, it is NOT sending the cache headers.

 

 

I'm kind of desperate to get this working because i'm serving VERY large image files, and mp3s, for a band who's on my servers, and fairly popular; which means that i'm about to get all of my bandwidth eaten.:

$expires = 60*60*24*365;
$size = filesize("{$client_directory}/{$_GET['did']}");
header("Content-Length: ".$size,true);
header("Cache-Control: max-age={$expires}, public, no-transform",true);
header('Expires: ' . gmdate('D, d M Y H:i:s', time()+$expires) . ' GMT',true);
header('Last-Modified: ' . gmdate('D, d M Y H:i:s', time()-$expires) . ' GMT',true);
header("Content-type: audio/example");
header("Content-Disposition: attachment; filename=\"{$_GET['did']}\"");
readfile("{$client_directory}/{$_GET['did']}");

Any help is appreciated.

 

[Vector]

Ok, i've got it sending the CORRECT cache headers now, but i am still not getting the "if-modified-since" header from the client.

 

Here's the client headers:

Host=ionisis.com
User-Agent=Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.0.15) Gecko/2009102704 Fedora/3.0.15-1.fc10 Firefox/3.0.15
Accept=text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language=en-us,en;q=0.5
Accept-Encoding=gzip,deflate
Accept-Charset=ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive=300
Connection=keep-alive
Referer=http://violentworkofart.test/?a=WCMS_Page_Display&id=156008001258174118&t=6_-_C.O.M.A.
Cookie=sssssssssssssssssssssssssssssss

 

and the server headers:

Status=OK - 200
Date=Mon, 23 Nov 2009 23:27:18 GMT
Server=Apache/2.2.11 (Fedora)
Content-Length=4400274
Cache-Control=max-age=31536000, public, no-transform
Expires=Tue, 23 Nov 2010 23:26:09 GMT
Last-Modified=Mon, 23 Nov 2009 23:26:09 GMT
Content-Disposition=attachment; filename="Coma.mp3"
Content-Encoding=gzip
Vary=Accept-Encoding
Keep-Alive=timeout=15, max=100
Connection=Keep-Alive
Content-Type=audio/example

 

But when i request the file over and over, the headers are the same. The client never sends the "if-modified-since" header, and so i can't tell if they've already downloaded it before so that i can send them the "not modified" header, instead of the file.