mod_xsendfile is a small Apache2 module that processes X-SENDFILE headers registered by the original output handler.
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 or any cgi.
Yep, it is useful.
mod_xsendfile.cd1a293e364626db25cc9d976b9dcc79d3dcdddff72d1f0084013695d611201b4Source tarball: mod_xsendfile-0.11.1.tar.gz145b15c5bd2bf0998fa30eef8ba42d8df94ba75709be8f127d5b2a74b4d2c4dbWin32 binaries: mod_xsendfile-0.11.1.zip2148b6ba3d1b4909ee29431a6dbb7e5ce1e8b3528dd6432f1dccc56c6a528377GitHub repository: http://github.com/nmaier/mod_xsendfileapxs -cia mod_xsendfile.c| 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.
If the response lacks the X-SENDFILE
header nothing is done.
| 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.
| 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.
| Description | White-list more paths |
|---|---|
| Syntax | XSendFilePath absolute path |
| Default | None |
| Context | server config, virtual host, directory |
XSendFilePath allow you to add additional paths to some kind of white list. All files within these paths are allowed to get served through mod_xsendfile.
Provide an absolute path as Parameter to this directive.
You may provide more than one path.
The current working directory (if it can be determined) will be always checked first.
If you provide relative paths via the X-SendFile header, then all whitelist items will be checked until a seamingly valid combination is found, i.e. the result is within the bounds of the whitelist item; it isn't checked at this point if the path in question actually exists.
Considering you whitelisted /tmp/pool and /tmp/pool2 and your script working directory is /var/www.
X-SendFile: file
/var/www/file - Within bounds of /var/www, OKX-SendFile: ../pool2/file
/var/www/../pool2/file = /var/pool2/file - Not within bounds of /var/www/tmp/pool/../pool2/file = /tmp/pool2/file - Not within bounds of /tmp/pool/tmp/pool2/../pool2/file = /tmp/pool2/file - Within bounds of /tmp/pool2, OKYou still can only access paths that are whitelisted. However you have might expect a different behavior here, hence the documentation.
The white list "inherits" entries from higher level configuration.
XSendFilePath /tmp <VirtualHost *> ServerName someserver XSendFilePath /home/userxyz </VirtualHost> <VirtualHost *> ServerName anotherserver XSendFilePath /var/www/somesite/ <Directory /var/www/somesite/fastcgis> XSendFilePath /var/www/shared </Directory> </VirtualHost>
Above example will give:
/tmp/tmp/home/userxyz/tmp/var/www/somesite/var/www/shared (for scripts* located in /var/www/somesite/fastcgis)*) Scripts, in this context, mean the actual script-starters. E.g. PHP as a handler will use the .php itself, while in CGI mode refers to the starter.
Windows users should take care to include the drive letter to those paths as well. Tests show that it has to be in upper-case.
.htaccess
<Files out.php>
XSendFile on
</Files>
out.php
<?php
...
if ($user->isLoggedIn())
{
header("X-Sendfile: $path_to_somefile");
header("Content-Type: application/octet-stream");
header("Content-Disposition: attachment; filename=\"$somefile\"");
exit;
}
?>
<h1>Permission denied</h1>
<p>Login first!</p>
Content-Encoding
header - if present - will be dropped, as the module
cannot know if it was set by intention of the programmer or the
handler. E.g. php with output compression enabled will set this header,
but the replacement file send via mod_xsendfile is most likely not
compressed.The idea comes from lighttpd - A fast web server with minimal memory footprint.
The module itself was inspired by many other Apache2 modules such as mod_rewrite, mod_headers and obviously core.c.
Copyright 2006-2010 by Nils Maier
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and limitations under the License.