#!/usr/bin/perl -w
#
# fake-pop3
# John Simpson <jms1@jms1.net> 2008-08-30
#
# simple implementation of POP3 server (defined in RFC 1939) which
# - accepts ANY authentication attempt
# - presents the client with what appears to be an empty mailbox
#
###############################################################################
#
# Copyright (C) 2008 John Simpson.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License, version 3, as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
###############################################################################

require 5.003 ;
use strict ;

my $state = 0 ;	# 0=authentication, 1=transaction

print "+OK fake-pop3\r\n" ;

while ( 1 )
{
	chomp ( my $input = <> ) ;
	my @w = split ( /\s+/ , $input ) ;
	my $cmd = uc shift @w ;

	if ( $cmd eq "QUIT" )
	{
		print "+OK goodbye\r\n" ;
		exit 0 ;
	}

	elsif (    ( $cmd eq "USER" )
		|| ( $cmd eq "PASS" )
		|| ( $cmd eq "APOP" ) )
	{
		print "+OK fake pop3 session, credentials are ignored\r\n" ;
	}

	elsif ( $cmd eq "STAT" )
	{
		print "+OK 0 0\r\n" ;
	}

	elsif (    ( $cmd eq "LIST" )
		|| ( $cmd eq "UIDL" ) )
	{
		my $n = shift @w ;
		print defined ( $n )
			? "-ERR no such message\r\n"
			: "+OK\r\n.\r\n" ;
	}

	elsif (    ( $cmd eq "RETR" )
		|| ( $cmd eq "DELE" )
		|| ( $cmd eq "TOP"  ) )
	{
		print "-ERR no such message\r\n" ;
	}

	elsif ( ( $cmd eq "NOOP" ) || ( $cmd eq "RSET" ) )
	{
		print "+OK\r\n" ;
	}

	else
	{
		print "-ERR unknown command\r\n" ;
	}
}