# Copyright (C) 2006 Phil Hobson, HCI Data Ltd - www.hcidata.info

# Permission is hereby granted, free of charge, to any person obtaining a copy of
# this software and associated documentation files (the "Software"), to deal in
# the Software without restriction, including without limitation the rights to
# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
# of the Software, and to permit persons to whom the Software is furnished to do
# so, subject to the following conditions:

# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

# NAME check_verybadrcptto
#
# This plugin helps other users when a spammer sends e-mails to several addresses, most of which are valid.
#
# Overall Logic:
#
# read qmail's "Very Bad RCPT To" file get the list of addresses (honeypots?) who only receive spam
# decline to do anything when given a recipient address but make a note if the recipient is in the "Very Bad RCPT To" list
# DENY the sending of data if a note of a recipient in the "Very Bad RCPT To" list was made
#
# NOTE
#       This MUST go before any other plugin that can DENY a RCPT address.
#
#       If this goes after such a plugin that has DENIED the RCPT address, then our "hook_rcpt" will not be run
#       and so we do not make a note to reject the whole e-mail as spam.
#       If there were multiple RCPT addresses, the e-mail may get through to other RCPT addresses.
#
#       If our hook_rcpt is run first, we make a note to reject the whole e-mail as spam and any other plugins can
#       run and send any other status codes to the sending system.
#       Even if there are more RCPT addresses that have not been DENIED, we have noted that the e-mail is spam and
#       will stop the data being received.
#
# Installation notes are at http://www.hcidata.info/qpsmtpd.htm

use Qpsmtpd::DSN;
use strict;

sub hook_rcpt {
  my ($self, $transaction, $recipient) = @_;
  return (DECLINED) unless $recipient->host && $recipient->user;  # there is no point continuing if we haven't got enough to work with!

  my @verybadmailto = $self->qp->config('verybadrcptto')  # there is no point continuing if we haven't got a "Very Bad RCPT To" list
    or return (DECLINED);

  my $userhost = lc $recipient->user . '@' .$recipient->host;

  for my $bad (@verybadmailto) {
    $bad =~ s/^\s*(\S+)\s*/$1/;
    next unless lc $bad eq $userhost;
    $self->log(LOGNOTICE,"$userhost is such a bad recipient that no data will be allowed to be sent");
    $transaction->notes('verybadrcptto',
       "sorry, one or more of the recipients has flagged this e-mail as unsolicited bulk/commercial " .
       "e-mail which is contrary to our acceptable e-mail use policy");
    last;
  }
  return (DECLINED);    # we are not going to do anything now.  We will take action later.
}

sub hook_data {
  my ($self, $transaction) = @_;
  my $note = $transaction->notes('verybadrcptto');
  return (DECLINED) unless $note;

  $self->log(LOGNOTICE,$note);
  sleep 1;              # may as well slow the spammer down a bit.
  return Qpsmtpd::DSN->media_unsupported("$note - spam score exceeded threshold");
}