=head1 NAME

rcpt_regexp - check recipients against a list of regular expressions

=head1 DESCRIPTION

B<rcpt_regexp> reads a list of regular expressions, return codes and comments
from the I<rcpt_regexp> config file. If the regular expression does NOT match
I<m#^(/.*/)$#>, it is used as a string which is compared with I<eq lc($rcpt)>.
The recipient addresses are checked against this list, and if the first 
matches, the return code from that line and the comment are returned to
qpsmtpd. Return code can be any valid plugin return code from 
L<Qpsmtpd::Constants>. Matching is always done case insenstive. 

=head1 CONFIG FILE

The config file I<rcpt_regexp> contains lines with a perl RE, including the 
"/"s, a return code and a comment, which will be returned to the sender, if 
the code is not OK or DECLINED. Example:

  # rcpt_regexp - config for rcpt_regexp plugin
  me@myhost.org           OK       Accepting mail
  /^user\d+\@doma\.in$/   OK       Accepting mail
  info@myhost.com         DENY     User not found.
  /^unused\@.*/           DENY     User not found.
  /^.*$/                  DECLINED Fall through to next rcpt plugin

=head1 NOTE

The C<rcpt_regexp> config file should be writeable by trusted users only: the
regexes are compiled with I<eval()>.

=head1 COPYRIGHT AND LICENSE

Copyright (c) 2005 Hanno Hecker

This plugin is licensed under the same terms as the qpsmtpd package itself.
Please see the LICENSE file included with qpsmtpd for details.

=cut

use Qpsmtpd::Constants;

sub hook_rcpt {
    my ($self, $transaction, $recipient) = @_;
    return (DECLINED)
      unless $recipient->host && $recipient->user;

    my $rcpt = lc $recipient->user . '@' . $recipient->host;
    my ($re, $const, $comment, $str, $ok, $err);

    foreach ($self->qp->config("rcpt_regexp")) {
        s/^\s*//;
        ($re, $const, $comment) = split /\s+/, $_, 3;
        $str = undef;
        if ($re =~ m#^/(.*)/$#) {
            $re = $1;
            $ok = eval { $re = qr/$re/i; };
            if ($@) {
                ($err = $@) =~ s/\s*at \S+ line \d+\.\s*$//;
                $self->log(LOGWARN, "REGEXP '$re' not valid: $err");
                next;
            }
            $re = $ok;
        }
        else {
            $str = lc $re;
        }

        unless (defined $const) {
            $self->(LOGWARN, "rcpt_regexp - no return code");
            next;
        }

        $ok    = $const;
        $const = Qpsmtpd::Constants::return_code($const);
        unless (defined $const) {
            $self->log(LOGWARN,
                           "rcpt_regexp - '$ok' is not a valid "
                         . "constant, ignoring this line"
                      );
            next;
        }

        if (defined $str) {
            next unless $str eq $rcpt;
            $self->log(LOGDEBUG, "String $str matched $rcpt, returning $ok");
        }
        else {
            next unless $rcpt =~ $re;
            $self->log(LOGDEBUG, "RE $re matched $rcpt, returning $ok");
        }

        return ($const, $comment);
    }
    return (DECLINED);
}

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