#!/usr/bin/perl -w

use strict;
use IO::Socket;
use Net::DNS;
use MIME::Lite;

sub mail_run;
sub send_letter($$$$);

my ($msg, $resp, $from_addr, $subject);
my $debug;
my ($child_count, $kid_pid);
my $conn_id;
my $sim_delivery = 30;

$| = 1;
$debug = 0;

while (my $arg = shift)
{
        if              ($arg eq '-d')  { $debug = 1 }
        elsif   ($arg eq '-s')  { $sim_delivery = shift or die "You must specify the number of simultaneous deliveries!\n" }
}

for ($child_count = 0; $child_count < $sim_delivery; $child_count++)
{
        if (!defined($kid_pid = fork()))
        {
                die "Couldn't fork!\n";
        } elsif ($kid_pid) {
                # I'm the daddy - don't do nothin, yet
        } else {
                mail_run;
                exit;
        }
}

while ($child_count > 0) { wait; $child_count--; }

sub snd
{
        my $sock = shift;
        my $msg = shift;

        my $len = length($msg);
        if ($debug) {print $conn_id . ": sent: $msg\n"}
        $msg = pack('N', $len) . $msg;
        syswrite($sock, $msg, length($msg));
}
sub rcv
{
        my $sock = shift;
        my $buf;
        my ($bytes_read, $total_read, $bytes_to_read);

        $bytes_read = sysread($sock, $buf, 4);
        if ($! || ($bytes_read != 4))
        {
                return undef;
        } else {
                $bytes_to_read = unpack('N',$buf);
                $total_read = 0;
                my $buf2 = $buf = undef;
                while ($total_read < $bytes_to_read)
                {
                        $bytes_read = sysread($sock, $buf, $bytes_to_read - $total_read);
                        $buf2 .= $buf;
                        $total_read += $bytes_read;
                }
                $buf = $buf2;
        }
        return $buf;
}

sub mail_run
{
        my $stop;
        my $server = IO::Socket::INET->new(
                        Proto           => 'tcp',
                        PeerAddr        => 'localhost',
                        PeerPort        => 6900 );

        $server->autoflush();

        $_ = rcv($server);
        ($conn_id) = /HELO (.*)/;
        if ($debug) {print "$conn_id: Connected to server\n"}

        $stop = 0;
        while (!$stop)
        {

                if (!defined $msg)
                {
                        if ($debug) {print "$conn_id: Getting message\n"}
                        snd($server,"get_msg");
                        $msg = rcv($server);
                        if (!defined $msg || $msg =~ /^FIN/)
                        {
                                snd($server,"quit");
                                $stop = 1;
                        } else {
                                ($from_addr, $subject, $msg) = split("\n", $msg, 3);
                        }
                } else {
                        if ($debug) {print "$conn_id: Requesting next address\n"}
                        snd($server,"next_addr");
                        $server->flush();
                        if ($debug) {print "$conn_id: Request sent...waiting\n"}
                        $resp = rcv($server);
                        $resp =~ s/[\r|\n]//g;
                        if ($debug) {print "$conn_id: server said: $resp\n"}
                        if ($resp eq 'FIN')
                        {
                                if ($debug) {print "$conn_id: Getting message\n"}
                                snd($server,"get_msg");
                                $msg = rcv($server);
                                if (!defined $msg || $msg eq 'FIN')
                                {
                                        if ($debug) {print "$conn_id: server said: FIN (msg)\n"}
                                        snd($server,"quit");
                                        $stop = 1;
                                } else {
                                        ($from_addr, $subject, $msg) = split("\n", $msg, 3);
                                }
                        } else {
                                if ($debug)
                                {
                                        print "$conn_id: From: $from_addr\nTo: $resp\nSubject: $subject\n";
                                        sleep 2;
                                } else {
                                        if (send_letter($from_addr, $resp, $subject, $msg))
                                        {
                                                snd($server,"succ_addr $resp");
                                        } else {
                                                snd($server,"fail_addr $resp");
                                        }
                                        $resp = rcv($server);
                                }
                        }
                }
        }
}
sub send_letter($$$$)
{
        my $from_addr = shift;
        my $to_addr = shift;
        my $subject = shift;
        my $body = shift;

        my $username = undef;
        my $domain = undef;

        my $success = 0;

        ######################
        # add email validation
        ######################
        if ( $to_addr =~ /\@/ )
        {
                ($username, $domain) = split /\@/, $to_addr;

                my $msg = MIME::Lite->new(
                        From    => $from_addr,
                        To              => $to_addr,
                        Subject => $subject,
                        Data    => $body,
                        Type    => 'text/html'
                        );

                my $res = Net::DNS::Resolver->new();
                my @mx = mx($res, $domain);

                my $i = 0;
                my $num_mx = @mx;

                while ($i < $num_mx && !$success)
                {
                        # print "\n$to_addr: ", $mx[$i]->exchange;
                        eval('$msg->send_by_smtp($mx[$i]->exchange, Timeout=>60)');
                        if ( !$@ ) { $success = 1 }
                        $i++;
                }
        }
        return $success;
}