I wonder if and how it is possible to write a custom protocol handler

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Asked: May 17, 20262026-05-17T20:26:58+00:00 2026-05-17T20:26:58+00:00

I wonder if and how it is possible to write a custom protocol handler

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I wonder if and how it is possible to write a custom “protocol handler” (listening at a custom port) for Apache 2 in PHP?

In C and mod_perl you can write so-called “protocol handlers”, which intercept the early Apache stage (after a client socket connection has been accept()ed, but before any content has been written to it) and can for example handle FTP or SMTP protocols. Is it possible in PHP as well?

For example, I have the following simple mod_perl handler, which I’d like to port to PHP (to compare the memory usage – since my mod_perl-handler needs 20m per child). My handler listens at the port 843 and writes the string POLICY to the client socket:

package SocketPolicy;

# Run: semanage port -a -t http_port_t -p tcp 843
# And add following lines to the httpd.conf
# Listen 843
# <VirtualHost _default_:843>
#       PerlModule                   SocketPolicy
#       PerlProcessConnectionHandler SocketPolicy
# </VirtualHost>

use strict;
use warnings FATAL => 'all';
use APR::Const(-compile => 'SO_NONBLOCK');
use APR::Socket();
use Apache2::ServerRec();
use Apache2::Connection();
use Apache2::Const(-compile => qw(OK DECLINED));

use constant POLICY =>
qq{<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM
"http://www.adobe.com/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
<allow-access-from domain="*" to-ports="8080"/>
</cross-domain-policy>
\0};

sub handler {
        my $conn   = shift;
        my $socket = $conn->client_socket();
        my $offset = 0;

        # set the socket to the blocking mode
        $socket->opt_set(APR::Const::SO_NONBLOCK => 0);

        do {
                my $nbytes = $socket->send(substr(POLICY, $offset),
                             length(POLICY) - $offset);
                # client connection closed or interrupted
                return Apache2::Const::DECLINED unless $nbytes;
                $offset += $nbytes;
        } while ($offset < length(POLICY));

        my $slog = $conn->base_server()->log();
        $slog->warn('served socket policy to: ', $conn->remote_ip());
        return Apache2::Const::OK;
}

1;

Thanks,
Alex