#!perl -w

=head1 NAME

exim-bsmtp

=head1 DESCRIPTION

This plugin enqueues mail from qpsmtpd into Exim via BSMTP

=head1 INSTALLATION

The qpsmtpd user B<must> be configured in the I<trusted_users> setting
in your Exim configuration.  If it is not, queueing will still work,
but sender addresses will not be honored by exim, which will make all
mail appear to originate from the smtpd user itself.

=head1 CONFIGURATION

The plugin accepts configuration settings in space-delimited name/value
pairs.  For example:

 queue/exim-bsmtp exim_path /usr/sbin/exim4

=over 4

=item exim_path I<path>

The path to use to execute the Exim BSMTP receiver; by default this is
I</usr/sbin/rsmtp>.  The commandline switch '-bS' will be added (this is
actually redundant with rsmtp, but harmless).

=back

=head1 LICENSE

Copyright (c) 2004 by Devin Carraway <qpsmtpd@devin.com>

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.

=cut

use strict;
use warnings;

use IO::File;
use Sys::Hostname qw(hostname);
use File::Temp qw(tempfile);
use Qpsmtpd::Constants;

sub register {
    my ($self, $qp, %args) = @_;

    $self->{_exim_path} = $args{exim_path} || '/usr/sbin/rsmtp';
    $self->{_exim_path} = $1 if $self->{_exim_path} =~ /(.*)/;
    unless (-x $self->{_exim_path}) {
        $self->log(LOGERROR,
                       "Could not find exim at $self->{_exim_path};"
                     . " please set exim_path in config/plugins"
                  );
        return undef;
    }
}

sub hook_queue {
    my ($self, $transaction) = @_;

    unless ($transaction->header) {
        $self->log(LOGERROR, "No header parsed for transaction; can't enqueue");
        return DENY, 'Mail unqueuable';
    }
    my $tmp_dir = $self->qp->config('spool_dir') || '/tmp';
    $tmp_dir = $1 if ($tmp_dir =~ /(.*)/);
    my ($tmp, $tmpfn) = tempfile("exim-bsmtp.$$.XXXXXX", DIR => $tmp_dir);
    unless ($tmp && $tmpfn) {
        $self->log(LOGERROR, "Couldn't create tempfile: $!");
        return DECLINED, 'Internal error enqueueing mail';
    }

    print $tmp "HELO ", hostname(), "\n",
      "MAIL FROM:<", ($transaction->sender->address || ''), ">\n";
    print $tmp "RCPT TO:<", ($_->address || ''), ">\n"
      for $transaction->recipients;
    print $tmp "DATA\n", $transaction->header->as_string;
    $transaction->body_resetpos;
    while (my $line = $transaction->body_getline) {
        $line =~ s/^\./../;
        print $tmp $line;
    }
    print $tmp ".\nQUIT\n";
    close $tmp;

    my $cmd = "$self->{_exim_path} -bS < $tmpfn";
    $self->log(LOGDEBUG, "executing cmd $cmd");
    my $exim = new IO::File "$cmd|";
    unless ($exim) {
        $self->log(LOGERROR, "Could not execute $self->{_exim_path}: $!");
        unlink $tmpfn or $self->log(LOGERROR, "unlink: $tmpfn: $!");
        return DECLINED, "Internal error enqueuing mail";
    }

    # Normally exim produces no output in BSMTP mode; anything that
    # does come out is an error worth logging.
    my $start = time;
    my ($bsmtp_error, $bsmtp_msg);
    while (<$exim>) {
        chomp;
        $self->log(LOGERROR, "exim: $_");
        if (/(\d\d\d)\s(\S.*)/) {
            ($bsmtp_error, $bsmtp_msg) = ($1, $2);
        }
    }
    $self->log(LOGDEBUG, "BSMTP finished (" . (time - $start) . " sec)");
    $exim->close;
    my $exit = $?;
    unlink $tmpfn or $self->log(LOGERROR, "unlink: $tmpfn: $!");

    $self->log(LOGDEBUG, "Exitcode from exim: $exit");
    if ($bsmtp_error && $bsmtp_error >= 400 && $bsmtp_error < 600) {
        $self->log(LOGERROR,
               "BSMTP enqueue failed; response $bsmtp_error" . " ($bsmtp_msg)");
        return $bsmtp_error < 400 ? DECLINED : DENY, $bsmtp_msg;
    }
    elsif (($exit >> 8) != 0 || $bsmtp_error) {
        $self->log(LOGERROR,
                       'BSMTP enqueue failed; exitcode '
                     . ($exit >> 8)
                     . " from $self->{_exim_path} -bS"
                  );
        return DECLINED, 'Internal error enqueuing mail';
    }

    $self->log(LOGINFO, "Enqueued to exim via BSMTP");
    return OK, "Queued!";
}