#!/usr/bin/perl -w
#
# listfilter
# John Simpson <jms1@jms1.net> 2004-02-19
#
# verify that a message is really from a given mailing list-
# searches for a given header and makes sure the line contains the given value
#
# IF the message is really from a given list
#   - exit 0, causing the directions in .qmail to continue to be processed
# OTHERWISE
#   - exit 99, preventing any further delivery
#
# call from .qmail as...
#   |listfilter headername value
#
# example: if you have a dummy email address "qmr@jms1.not" which should
# only be receiving messages from a certain mailing list, and the mailing
# list always adds the header...
#	List-Post: <mailto:qmr@list.qmailrocks.org>
# you can make sure that a given message actually came from this list using
# this line in the user's .qmail file...
#	|listfilter List-Post qmr@list.qmailrocks.org
# and anything sent to this user which doesn't have the correct header to
# identify it as part of the mailing list, will be deleted automatically.
#
# you can also combine this with "condredirect" to redirect mailing list
# messages to a certain folder, in cases where you can't subscribe to a
# list directly under the dummy email address. for the same mailing list
# as above, i could add this to my normal user's .qmail file...
#	|condredirect qmr@jms1.not listfilter List-Post qmailrocks.org
# and any messages which arrive with the list's magic header will be
# automatically re-sent to the dummy user.
#
# 2005-04-11 jms1 - (code not modifed) added GPL-2-ONLY copyright notice,
#   expanded on the documentation above.
#
###############################################################################
#
# Copyright (C) 2004-2005 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 2, 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, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
# or visit http://www.gnu.org/licenses/gpl.txt
#
###############################################################################

require 5.003 ;
use strict ;

my ( $header , $value , $inh , $found ) ;

$header = shift || die "Header name not specified\n" ;
$value  = shift || die "Expected value not specified\n" ;

$inh = 1 ;
$found = 0 ;

while ( my $line = <> )
{
	next unless $inh ;

	chomp $line ;
	if ( $line =~ /^$/ )
	{
		$inh = 0 ;
		next ;
	}

	if ( $line =~ /^$header\:/ )
	{
		if ( $line =~ /$value/ )
		{
			$found = 1 ;
		}
	}
}

exit ( $found ? 0 : 99 ) ;