#!/usr/bin/env perl

my $eng_dns = "141.217.202.31";
my $wsu_dns = "141.217.154.162";

my @eng_doms = qw/
eng.wayne.edu
/;

my @wsu_doms = qw/
bc.accs.wayne.edu
chem.wayne.edu
cs.wayne.edu
eng.wayne.edu
gluon.physics.wayne.edu
hal.physics.wayne.edu
igloo.wayne.edu
lists.wayne.edu
mail.physics.wayne.edu
wayne.edu
opus.pass.wayne.edu
physics.wayne.edu
thermal.physics.wayne.edu
web-prod.wayne.edu
zimbra.wayne.edu
hr.wayne.edu
busops.wayne.edu
compbio.med.wayne.edu
wdet.org
detfm.org
/;


printf("%-20s %-40s %-8s\n", "Domain", "MX Value", "TTL");
print "-" x 20, " ", "-" x 40, " ", "-" x 8, "\n";

foreach my $dom (@eng_doms) {
    foreach my $mx (@{get_mx($dom, $eng_dns)}) {
        if ($mx->{mx} =~ /(?:wsu-ironport01|mx1\.wayne\.edu)/) {
            printf("%-20s %-40s %-8s\n", $dom, $mx->{mx}, $mx->{ttl});
        }
    }
}

foreach my $dom (@wsu_doms) {
    foreach my $mx (@{get_mx($dom, $wsu_dns)}) {
        if ($mx->{mx} =~ /(?:wsu-ironport01|mx1\.wayne\.edu)/) {
            printf("%-20s %-40s %-8s\n", $dom, $mx->{mx}, $mx->{ttl});
        }
    }
}

sub get_mx {
    my ($host, $dns) = @_;

    die "invalid hostname\n" unless $host =~ /^[\w\.\-]+$/;
    die "invalid dns\n" unless $dns =~ /^[\w\.\-]+$/;

    open(DIG, '-|', "dig -t MX \@$dns $host");

    my $answer = 0;
    my $response = [];
    while (my $line = <DIG>) {
        last if $answer && $line =~ /^[\r\n]}$/;
        if ($answer) {
            if ($line =~ /^$host\.\s+(\d+)\s+IN\s+MX\s+(.+)[\r\n]+$/) {
                push(@$response, { ttl => $1, mx => $2 });
            }
        } elsif ($line =~ /ANSWER SECTION/) {
            $answer = 1;
        }
    }

    close(DIG);

    return $response;
}