#!/usr/bin/perl
##FIXME : REMOVE THE -w above when the code is fixed !
#
#This is headers_filter.pl v0.2a
#
#Changelog
#Dec 03 : v0.2a Fix a bug when email address contains a "&"
#               The fix is dirty, and requires more thinking
#               But it works.
#
#Filters emails (send it headers+body) in order to hide your network mail hops from the outside world.
#
#
#Author : Vincent Deffontaines <vincent@gryzor.REMOVETHISIFNOSPAM.com>
#Copyright : Vincent Deffontaines, KDX (www.kdx.fr), Council of Europe (www.coe.int)  (c) 2002
#
#Please send me contributions/ modifications/ comments that could be useful to this script!
#
#This program is free software; you can redistribute it and/or
#modify it under the terms of the GNU General Public License
#as published by the Free Software Foundation; version 2
#of the License.
#
#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.
#



#For DEBUG ONLY, not on prod
#use Data::Dumper;

#Maybe this one could be commented too for performance
use strict;

my $sendmail = "/usr/lib/sendmail";

my %filtered_patterns = ();

#Data is in this part of the script, so it loads faster.
#Have a look at your email headers and set this up
#If you see
#
#########################
#Received: from foo.bar.com [whatever stuff here]
#    by foobar.bar.com blah blah
#    for user@bar.com
#    id <anyIDyoulike>
##########################
#you will set up this :
push @{$filtered_patterns{'Received: from foo.bar.com'}}, "\\s+by\\s+";
push @{$filtered_patterns{'Received: from foo.bar.com'}}, "\\s+for\\s+";
push @{$filtered_patterns{'Received: from foo.bar.com'}}, "\\s+id\\s+";

# The code below will interpret it as :
# Line with "Received: from foo.bar.com" is filtered, and lines just below it that start with \s+{by/for/id}
# will be filtered too.

#you can setup several "sections" to filter, eg:
push @{$filtered_patterns{'Received: by foo.bar.com'}}, "\\s+id\\s+";
#Which is a common one too.


#This optimises filtering : whenever one line starts with one of these elements, script stops 
#looking at lines and just outputs the input as it received it.
#By default only the header is filtered, NEVER the body, so this is just to make things faster.
my @stop_filtering_patterns = (
   "Message-ID:",
   "From:",
   "To:",
   "Subject:",
   "Date:",
   "Mime-Version:",
   "X-Mailer:",
   "Content-Type"
);

my $end_filtering = 0;
my $filter = 0;
my $patt = "";

#We quote "&" else they will be damned interpreted when we run sendmail
#Probably more thinking must be performed here, and probably more things need to be filtered or quoted.
foreach my $argument(@ARGV)
{
   $argument =~ s/&/\\&/;
}

open (SENDMAIL, "|$sendmail @ARGV") or die "Couldn't fork: $!\n";

while (not $end_filtering){
   my $line = <STDIN>;
   my $filter_this_line =0;
   $line =~ /^$/ and $end_filtering = 1;
   foreach my $pattern (@stop_filtering_patterns)
   {
      $line =~/^$pattern/ and $end_filtering =1;
   }
   if ($end_filtering)
   {
      print SENDMAIL $line;
      next;
   }
   
   foreach my $pattern (keys %filtered_patterns)
   {
      if ($line =~/^$pattern/)
      {
         $filter_this_line = 1;
	 $filter = 1;
	 $patt = $pattern;
	 last;
      }
   }
   if ($filter)
   {   
#      print STDERR "DEBUG : ".Dumper($filtered_patterns{$patt})."\n";
      foreach my $subpattern(@{$filtered_patterns{$patt}})
      {
         if ($line =~ /^$subpattern/)
         {
            $filter_this_line = 1;
	    last;
         }
      }
      unless ($filter_this_line)
      {
         $filter = 0;
      }
   }
   unless ($filter_this_line)
   {
      print SENDMAIL $line;
   }
}   

while (<STDIN>){print SENDMAIL $_;}
print SENDMAIL ".\n";
close SENDMAIL;