#!/usr/bin/perl

use strict;
use warnings;


$| = 1;
open(STDERR, ">>/var/log/constatd.log") || die "Can't write to file: $!\n";

my $arg = shift;
my $pid;

if ( $arg =~ /^stop$/i )
{
	&terminate;
	exit;
}
elsif ( $arg =~ /^restart$/i )
{

	&terminate;
	$pid = &start;
}
elsif ( $arg =~ /^start$/i )
{
	if ( -f '/var/run/constatd.lock' )
	{
		print "constatd already running\n";
		exit;
	}
	$pid = &start;
}
elsif ( $arg =~ /^status$/i )
{
	if ( -f '/var/run/constatd.lock' )
	{
		open LOCK, "</var/run/constatd.lock";
			my @pid = <LOCK>;
		close LOCK;
		print "constatd running with pid $pid[0]\n";
		exit;
	}
	else
	{
		print "constatd is stopped\n";
		exit;
	}
}
else
{
	print "Unknown argument. Usage: [start|stop|restart|status]\n";
	exit;
}


if ( !$pid )
{
	my $failed_pass;
	while(1)	
	{
		my @servers = ('google.co.uk', 'bbc.co.uk', 'yahoo.co.uk');
		foreach (@servers)
		{
			my $result = &check_connection($_);
			if ( $result )
			{
				$failed_pass++;
				next;
			}
			else
			{
				$failed_pass = 0;
				last;	
			}
		}
		if ( $failed_pass > scalar(@servers) )
		{
			print STDERR time . ": Reboot required\n";
			&reboot_router;
			$failed_pass = 0;
		}
		sleep(300);
	}
}
else
{

	print STDERR time . ": contstatd started with pid $pid\n";
		
	open LOCK, ">/var/run/constatd.lock";
		print LOCK $pid;
	close LOCK;

}

sub start
{
	my $pid = fork();
	print "constatd start: [OK]\n" if $pid;
	return $pid;
}

sub terminate
{	
	my $pid;
	if ( -f '/var/run/constatd.lock' )
	{
		open PID, "</var/run/constatd.lock";
			my @lock_contents = <PID>;
		close PID;
		$pid = $lock_contents[0];
	}
	else
	{
		print "constatd stop: [FAILED]\n";
		exit;
	}
	print STDERR time . ": contstatd closing pid $pid\n";
	if (kill 'KILL', $pid)
	{
		print STDERR time . ": Closed pid $pid\n";
		print "constatd stop: [OK]\n";
		unlink '/var/run/constatd.lock';
	}
	else
	{
		print STDERR time . ": PANIC error closing pid $pid $!\n";
		print "constatd stop: [FAILED]\n";
	}
}


sub check_connection
{
	my $server = shift;
	use IO::Socket::INET;
	my $sock = new IO::Socket::INET
	(
	    PeerAddr=>$server,
	    PeerPort=>80,
	    Proto=>'tcp',
	);
	if ($sock)
	{
		print STDERR time .": Connection OK to $server.\n";
		$sock->close;
		return;
	}
	else
	{
		print STDERR time .": Socket could not be created to $server.\n";
		return 1;
	}
}



sub reboot_router
{
	use LWP::UserAgent;
	my $ua = LWP::UserAgent->new;
	$ua->agent("constatd/0.1 ");
	$ua->credentials(
		'192.168.0.1:80',
		'NETGEAR DG834GT ',
		'username' => 'password'
	);
	my $req = HTTP::Request->new(POST => 'http://192.168.0.1/setup.cgi');
	$req->content_type('application/x-www-form-urlencoded');
	$req->content('Reboot=Reboot&todo=reboot&this_file=diag.htm&next_file=diag.htm');
	my $result = $ua->request($req);
	print STDERR $result->content;
}