qpsmtpd/plugins/check_badmailfrom

#!perl -w

=head1 NAME

check_badmailfrom - checks the badmailfrom config, with per-line reasons

=head1 DESCRIPTION

Reads the "badmailfrom" configuration like qmail-smtpd does.  From the
qmail-smtpd docs:

"Unacceptable envelope sender addresses. qmail-smtpd will reject every
recipient address for a message if the envelope sender address is
listed in badmailfrom. A line in badmailfrom may be of the form
@host, meaning every address at host."

You may include an optional message after the sender address (leave a space),
to be used when rejecting the sender.


=head1 PATTERNS

This plugin also supports regular expression matches. This allows
special patterns to be denied (e.g. FQDN-VERP, percent hack, bangs,
double ats).

Patterns are stored in the format pattern(\s+)response, where pattern
is a Perl pattern expression. Don't forget to anchor the pattern
(front ^ and back $) if you want to restrict it from matching
anywhere in the string.

 ^streamsendbouncer@.*\.mailengine1\.com$    Your right-hand side VERP doesn't fool me
 ^return.*@.*\.pidplate\.biz$                I don' want it regardless of subdomain
 ^admin.*\.ppoonn400\.com$


=head1 NOTES

According to the SMTP protocol, we can't reject until after the RCPT
stage, so store it until later.


=head1 AUTHORS

initial author of badmailfrom - Jim Winstead

pattern matching plugin - Johan Almqvist <johan-qpsmtpd@almqvist.net>

merging of the two and plugin tests - Matt Simerson <matt@tnpi.net>

=cut

sub hook_mail {
    my ($self, $transaction, $sender, %param) = @_;

    my @badmailfrom = $self->qp->config('badmailfrom');
    if ( defined $self->{_badmailfrom_config} ) {       # testing
        @badmailfrom = @{$self->{_badmailfrom_config}};
    };

    return DECLINED if $self->is_immune();
    return DECLINED if $self->is_immune_sender( $sender, \@badmailfrom );

    my $host = lc $sender->host;
    my $from = lc($sender->user) . '@' . $host;

    for my $config (@badmailfrom) {
        $config =~ s/^\s+//g;   # trim leading whitespace
        my ($bad, $reason) = split /\s+/, $config, 2;
        next unless $bad;
        next unless $self->is_match( $from, $bad, $host );
        $reason ||= "Your envelope sender is in my badmailfrom list";
        $transaction->notes('badmailfrom', $reason);
    }
    return DECLINED;
}

sub is_match {
    my ( $self, $from, $bad, $host ) = @_;

    if ( $bad =~ /[\/\^\$\*\+]/ ) {  # it's a regexp
        $self->log(LOGDEBUG, "badmailfrom pattern ($bad) match for $from");
        return 1 if $from =~ /$bad/;
        return;
    };

    $bad = lc $bad;
    if ( $bad !~ m/\@/ ) {
        $self->log(LOGWARN, "badmailfrom: bad config: no \@ sign in $bad");
        return;
    };
    if ( substr($bad,0,1) eq '@' ) {
        return 1 if $bad eq "\@$host";
        return;
    };
    return if $bad ne $from;
    return 1;
};

sub hook_rcpt {
    my ($self, $transaction, $rcpt, %param) = @_;
    my $note = $transaction->notes('badmailfrom') or return (DECLINED);

    $self->log(LOGINFO, $note);
    return (DENY, $note);
}

sub is_immune_sender {
    my ($self, $sender, $badmf ) = @_;

    if ( ! scalar @$badmf ) {
        $self->log(LOGDEBUG, 'skip: empty list');
        return 1;
    };

    if ( ! $sender || $sender->format eq '<>' ) {
        $self->log(LOGDEBUG, 'skip: null sender');
        return 1;
    };

    if ( ! $sender->host || ! $sender->user ) {
        $self->log(LOGDEBUG, 'skip: missing user or host');
        return 1;
    };

    return;
};