2.4.x/docs/manual/mod/mod_proxy_fdpass.xml

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<modulesynopsis metafile="mod_proxy_fdpass.xml.meta">

<name>mod_proxy_fdpass</name>
<description>fdpass external process support module for
<module>mod_proxy</module></description>
<status>Extension</status>
<sourcefile>mod_proxy_fdpass.c</sourcefile>
<identifier>proxy_fdpass_module</identifier>
<compatibility>Available for unix in version 2.3 and later</compatibility>

<summary>
    <p>This module <em>requires</em> the service of <module
    >mod_proxy</module>. It provides support for the passing the socket of the
    client to another process.</p>

    <p><code>mod_proxy_fdpass</code> uses the ability of AF_UNIX domain
    sockets to <a href="http://www.freebsd.org/cgi/man.cgi?query=recv">pass an
    open file descriptor</a> to allow another process to finish handling a request.
    </p>

    <p>The module has a <code>proxy_fdpass_flusher</code> provider interface,
    which allows another module to optionally send the response headers, or even
    the start of the response body.  The default <code>flush</code> provider
    disables keep-alive, and sends the response headers, letting the external
    process just send a response body.
    </p>
    
    <p>In order to use another provider, you have to set the <code>flusher</code>
    parameter in the <directive module="mod_proxy">ProxyPass</directive> directive.
    </p>

    <p>At this time the only data passed to the external process is the client
    socket. To receive a client socket, call recvfrom with an allocated
    <a href="http://www.kernel.org/doc/man-pages/online/pages/man3/cmsg.3.html"
    ><code>struct cmsghdr</code></a>. Future versions of this module may include
    more data after the client socket, but this is not implemented at this time.
    </p>
</summary>

<seealso><module>mod_proxy</module></seealso>
</modulesynopsis>