#!/usr/bin/perl
use strict;
use warnings;
use Sendmail::PMilter;
my $conn = 'local:/var/run/mymilter.sock';
my $milter = Sendmail::PMilter->new();
$milter->setconn($conn);
$milter->register('mymilter',
                  {}
                  Sendmail::PMilter::SMFI_CURR_ACTS
                 );
$< = $> = getpwnam 'nobody';
$milter->main()

##</code><code>##

$milter->register('mymilter',
                  {
                      envrcpt => \&my_envrcpt_callback,
                  },
                  Sendmail::PMilter::SMFI_CURR_ACTS
                 );
openlog 'mymilter', 'pid', Unix::Syslog::LOG_MAIL();

##</code><code>##

use Unix::Syslog qw(:macros :subs);
sub is_valid_host
{
    my $host = shift;
    return undef unless $host;
    my ($name,$aliases,$addrtype,$net) = gethostbyname($host);
    defined $name;
}

sub my_envrcpt_callback
{
    my $ctx = shift;

    my $rcpt_addr = $ctx->getsymval('{rcpt_addr}');
    my ($fqdn) = ($rcpt_addr =~ /\@(\S+)/);

    if (not is_valid_host($fqdn))
    {
        # no such machine?
        syslog LOG_INFO, "$$: Rejected mail for $fqdn";

        return Sendmail::PMilter::SMFIS_ACCEPT;
    }

    Sendmail::PMilter::SMFIS_ACCEPT;
}

##</code><code>##

my %cache;
sub is_valid_host
{
    my $host = shift;
    return undef unless $host;

    $host = lc $host;
    unless (exists $cache{$host})
    {
        my ($name,$aliases,$addrtype,$net) = gethostbyname($host);
        $cache{$host} = $name;
    }
    $cache{$host};
}

##</code><code>##

        ++$msg_count;
        $0 = "[mymilter:$msg_count@" . scalar(localtime) . "] Checking $fqdn ($rcpt_addr)";

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;

use Sendmail::PMilter;
use Unix::Syslog qw(:macros :subs);

my $conn = 'inet:33333@127.0.0.1';
$ENV{PMILTER_DISPATCHER} = 'prefork';

my %cache;
sub is_valid_host
{
    my $host = shift;
    return undef unless $host;

    $host = lc $host;
    unless (exists $cache{$host})
    {
        my ($name,$aliases,$addrtype,$net) = gethostbyname($host);
        $cache{$host} = $name;
    }
    $cache{$host};
}

$SIG{ALRM} = sub { die "alarm\n" };

{
    my $msg_count = 0;
    sub my_envrcpt_callback
    {
        my $ctx = shift;

        # if we're not used in 30 seconds, quit.
        alarm 30;

        my $rcpt_addr = $ctx->getsymval('{rcpt_addr}');
        my ($fqdn) = ($rcpt_addr =~ /\@(\S+)/);
        ++$msg_count;
        $0 = "[mymilter:$msg_count@" . scalar(localtime) . "] Checking $fqdn ($rcpt_addr)";

        if (not is_valid_host($fqdn))
        {
            # no such machine?
            syslog LOG_INFO, "$$: Rejected mail for $fqdn";

            return Sendmail::PMilter::SMFIS_REJECT;
            #return Sendmail::PMilter::SMFIS_ACCEPT;
        }

        Sendmail::PMilter::SMFIS_ACCEPT;
    }
}

my $milter = Sendmail::PMilter->new();
$milter->setconn($conn);
$milter->register('mymilter',
                  {
                      envrcpt => \&my_envrcpt_callback,
                  },
                  Sendmail::PMilter::SMFI_CURR_ACTS
                 );

openlog 'mymilter', 'pid', Unix::Syslog::LOG_MAIL();

$< = $> = getpwnam 'nobody';

syslog LOG_INFO, "Starting up: $$";

END { closelog }

$milter->main(10,100);