qpsmtpd/plugins/check_relay

# this plugin checks the relayclients config file and
# $ENV{RELAYCLIENT} to see if relaying is allowed.
#

use Net::IP qw(:PROC);

sub hook_connect {
  my ($self, $transaction) = @_;
  my $connection = $self->qp->connection;

  # Check if this IP is allowed to relay
  my $client_ip = $self->qp->connection->remote_ip;

  # @crelay... for comparing, @srelay... for stripping
  my (@crelay_clients, @srelay_clients);

  my @relay_clients = $self->qp->config("relayclients");
  for (@relay_clients) {
    my ($range_ip, $range_prefix) = ip_splitprefix($_);
    if($range_prefix){
      # has a prefix, so due for comparing
      push @crelay_clients, $_;
    }
    else {
      # has no prefix, so due for splitting
      push @srelay_clients, $_;
    }
  }
  
  if (@crelay_clients){
    my ($range_ip, $range_prefix, $rversion, $begin, $end, $bin_client_ip);
    my $cversion = ip_get_version($client_ip);
    for (@crelay_clients) {
      # Get just the IP from the CIDR range, to get the IP version, so we can
      # get the start and end of the range
      ($range_ip, $range_prefix) = ip_splitprefix($_);
      $rversion = ip_get_version($range_ip);
      ($begin, $end) = ip_normalize($_, $rversion);

      # expand the client address (zero pad it) before converting to binary
      $bin_client_ip = ip_iptobin(ip_expand_address($client_ip, $cversion), $cversion);

      if (ip_bincomp($bin_client_ip, 'gt', ip_iptobin($begin, $rversion)) 
        && ip_bincomp($bin_client_ip, 'lt', ip_iptobin($end, $rversion)))
      {
        $connection->relay_client(1);
        last;
      }
    }
  }

  # If relay_client is already set, no point checking again
  if (@srelay_clients && !$connection->relay_client) {
    my $more_relay_clients = $self->qp->config("morerelayclients", "map");
    my %srelay_clients = map { $_ => 1 } @srelay_clients;
    $client_ip =~ s/::/:/;
	($connection->relay_client(1) && undef($client_ip)) if $client_ip eq ":1";

    while ($client_ip) {
      if (exists($ENV{RELAYCLIENT}) or
          exists($srelay_clients{$client_ip}) or
          exists($more_relay_clients->{$client_ip}))
      {
        $connection->relay_client(1);
        last;
      }
      $client_ip =~ s/(\d|\w)+(:|\.)?$//; # strip off another 8 bits
    }
  }
  return (DECLINED);
}