qpsmtpd/plugins/check_relay

# this plugin checks the standard rcpthosts config and
# $ENV{RELAYCLIENT} to see if relaying is allowed.
#
# It should be configured to be run _LAST_!
#

sub register {
  my ($self, $qp) = @_;
  $self->register_hook("rcpt", "check_relay");
}

sub check_relay {
  my ($self, $transaction, $recipient) = @_;
  my $host = lc $recipient->host;

  my @rcpt_hosts = ($self->qp->config("me"), $self->qp->config("rcpthosts"));
  
  # Allow 'no @' addresses for 'postmaster' and 'abuse'
  # qmail-smtpd will do this for all users without a domain, but we'll
  # be a bit more picky.  Maybe that's a bad idea.
  my $user = $recipient->user;
  $host = $self->qp->config("me")
    if ($host eq "" && (lc $user eq "postmaster" || lc $user eq "abuse"));

  # Check if this IP is allowed to relay
  my @relay_clients = $self->qp->config("relayclients");
  my $more_relay_clients = $self->qp->config("morerelayclients", "map");
  my %relay_clients = map { $_ => 1 } @relay_clients;
  my $client_ip = $self->qp->connection->remote_ip;
  while ($client_ip) {
    if (exists($ENV{RELAYCLIENT}) or
        exists($relay_clients{$client_ip}) or
        exists($more_relay_clients->{$client_ip}))
    {
      $transaction->relaying(1);
      return (OK);
    }
    $client_ip =~ s/\d+\.?$//; # strip off another 8 bits
  }
  
  # Check if this recipient host is allowed
  for my $allowed (@rcpt_hosts) {
    $allowed =~ s/^\s*(\S+)/$1/;
    return (OK) if $host eq lc $allowed;
    return (OK) if substr($allowed,0,1) eq "." and $host =~ m/\Q$allowed\E$/i;
  }

  my $more_rcpt_hosts = $self->qp->config('morercpthosts', 'map');
  return (OK) if exists $more_rcpt_hosts->{$host};

  return (DENY);
}