eliminate-dups

#! /usr/bin/perl
#----------------------------------------------------------------------
# Copyright 2006 Russell Nelson <nelson@crynwr.com>
# This program is free software; you can redistribute it and/or
# modify it under the same terms as Perl itself.
#----------------------------------------------------------------------
#
# Call from a .qmail file as follows:
#    | eliminate-dups hashname
#    &user-delivery@domain
#and create a NEW .qmail-delivery file containing
#
#    /home/user/mbox
#
#Now, if delivery to the mbox is deferred, eliminate-dups will NOT be
#run a second time for the same message.

$hashname = shift;

use MD5;
$md5 = new MD5;

$loose = 1;			# loose matching if set.

while(<>) {
    last if /^$/;
    next if $ignore_continue && /^\s/;
    $ignore_continue = 0;
    if (/^received:/i) {
	$ignore_continue = 1;
	next;
    }
    if (!$loose) {
	$headers .= $_;
	next;
    }
    if ($keep_continue && /^\s/) {
	$headers .= $_;
	next;
    }
    $keep_continue = 0;
    if (m/^(from|message-id|date):/i) {
	$headers .= $_;
	$keep_continue = 1;
	next;
    }
    next;
}

$md5->add($headers);
$md5->addfile(STDIN);
$hash = $md5->hexdigest;
print "$headers Our hash:$hash\n";

if (open(HASH, "<$hashname.newer")) {
    flock(HASH, 2);
    while(<HASH>) { chomp; exit 99 if $_ eq $hash; }
}
open(HASH, "<$hashname.older") || die "$0: Cannot open $hashname.older";
while(<HASH>) { chomp; exit 99 if $_ eq $hash; }

# roll the files once a week.
if (-M "$hashname.older" > 7) {
	rename("$hashname.newer", "$hashname.older") || die "$0: Unable to move newer to older";
}

# add the hash to the "received messages" list.
open(HASH, ">>$hashname.newer") || die "$0: Cannot append to $hashname.newer";
print HASH "$hash\n";
close(HASH);

print "Original message";
exit 0;