#!/usr/local/bin/perl

# An exceedingly simple server using Authen::Krb4

use IO::Socket;
use Sys::Hostname;
use Authen::Krb4;

$SERVER_PORT=6789;
$SERVICE='rcmd';

$sock=new IO::Socket::INET(
	LocalPort	=> $SERVER_PORT,
	Proto		=> 'tcp',
	Listen		=> 5,
	Reuse		=> 1
);

$sock or die "couldn't create socket";

# get instance for requested service
$phost=Authen::Krb4::get_phost(hostname());

while ($new_sock=$sock->accept()) {
	while (defined($buf=<$new_sock>)) {
		$dat.=$buf;

		# read up to ___END_TICKET
		if ($buf=~/___END_TICKET/) {
			$dat=~s/___END_TICKET\n//;
			last;
		}

	}

	# create a new ticket with the data from the client
	$ticket=new Authen::Krb4::Ticket($dat);

	# decrypt ticket & see what we've got
	$ad=Authen::Krb4::rd_req($ticket,$SERVICE,$phost,"");

	# send a message back to the client
	if ($ad) {
		print $new_sock "Hello, ",$ad->pname,"!\n";
	}
	else {
		print $new_sock "Couldn't decode your ticket!\n";
	}
	close($new_sock);
}