#!/usr/bin/perl -w

use strict;
use Getopt::Long;

my $host_file = "$ENV{HOME}/etc/hostlist.monitor";
my $nc = '/usr/pkg/sbin/nc';

my $mail_host = 'localhost';
my @mail_recip = ();
my $debug = 0;

GetOptions('file=s' => \$host_file, 'debug' => \$debug,
	'mailhost=s' => \$mail_host, 'recipients=s' => \@mail_recip);
@mail_recip = split(/,/, join(',', @mail_recip));

@mail_recip = qw(change@me.dom) if ($#mail_recip < 0);

open HFILE, "<$host_file";

my ($host, $port, $send, $recv, $state);

my $report = '';

while (<HFILE>) {
	chomp($_);
	($host, $port, $send, $recv) = split(':', $_);
	chomp($state = `/bin/echo $send | $nc $host $port`);
	print "[$state][$recv]\n" if $debug;
	if ($state ne $recv) {
		$report .= "Services at port $port on $host seem to be down.\n";
	}
}

close HFILE;

if ($report) {
	use Net::SMTP;

	if ($debug) {
		print $report;
		exit 1;
	}

	my $smtp = Net::SMTP->new($mail_host);

	chomp(my $mail_subject = `basename $0`);
	$mail_subject .= " report at " . localtime;
	my $from = (split('\(', (split('\)', `id`))[0]))[1]
		. '@' . `hostname`;

	$smtp->mail($from);
	foreach (@mail_recip) {
		$smtp->recipient($_);
	}
	$smtp->data();
	$smtp->datasend("To: " . join(', ', @mail_recip) . "\n");
	$smtp->datasend("Subject: $mail_subject\n\n");
	$smtp->datasend("There appears to be a system outtage problem:\n\n");
	$smtp->datasend($report);
	$smtp->datasend("\nComputer operator, please page the Unix sysadmin.\n");
	$smtp->dataend;
	$smtp->quit;
}