mod_xsendfile

mod_xsendfile for Apache 2

Overview

mod_xsendfile is a small Apache2 module that processes X-SENDFILE headers output handlers might have registered.

If it encounters the presence of such header it will discard all output and send the file specified by that header instead using Apache internals including all optimizations like caching-headers and sendfile or mmap if configured.

It is useful for processing script-output of e.g. php, perl, python or any *cgi.

Useful?

Yep, it is useful.

• Some applications require checking for special privileges.
• Other have to lookup values first (e.g.. from a DB) in order to correctly process a download request.
• Or store values (download-counters come into mind).

Benefits

• Uses apache internals
• Optimal delivery through sendfile and mmap (if available).
• Sets correct cache headers such as Etag and If-Modified-Since as if the file was statically served.
• Processes cache headers such as If-None-Match or If-Modified-Since.
• Support for ranges.

Installation

1. Grab the source.
2. Compile and install
   • In general: apxs -cia mod_xsendfile.c
   • Debian/Ubuntu uses apxs2: apxs2 -cia mod_xsendfile.c
   • Mac users might want to build fat binaries: apxs -cia -Wc,"-arch i386 -arch x86_64" -Wl,"-arch i386 -arch x86_64" mod_xsendfile.c
3. Restart apache
4. That’s all.

Configuration

Headers

• X-SENDFILE - Send the file referenced by this headers instead of the current response body
• X-SENDFILE-TEMPORARY - Like X-SENDFILE, but the file will be deleted afterwards. The file must originate from a path that has the AllowFileDelete flag set.

XSendFile

Description Enables or disables header processing
Syntax XSendFile on | off
Default XSendFile off
Context Server config, virtual host, directory, .htaccess

Setting XSendFile on will enable processing

The file specified in X-SENDFILE header will be sent instead of the handler output.

The value (file name) given by the header is assmumed to be url-encoded, i.e. unescaping/url-decoding will be performed. See XSendFileUnescape. If you happen to store files using already url-encoded file names, you must “double” encode the names… %20 -> %2520

If the response lacks the X-SENDFILE header the module will not perform any processing.

XSendFileIgnoreEtag

Description Ignore script provided Etag headers
Syntax XSendFileIgnoreEtag on | off
Default XSendFileIgnoreEtag off
Context Server config, virtual host, directory, .htaccess

Setting XSendFileIgnoreEtag on will ignore all ETag headers the original output handler may have set. This is helpful for applications that will generate such headers even for empty content.

XSendFileIgnoreLastModified

Description Ignore script provided LastModified headers
Syntax XSendFileIgnoreLastModified on | off
Default XSendFileIgnoreLastModified off
Context Server config, virtual host, directory, .htaccess

Setting XSendFileIgnoreLastModified on will ignore all Last-Modified headers the original output handler may have set. This is helpful for applications that will generate such headers even for empty content.

XSendFileUnescape