#! /usr/bin/perl
#
# check_wireless_ssid <device> <ssid> [warn] [critical] [port]
#
# Nagios host script to check if a wireless SSID exists.  Relies on iwlist
# to scan for SSIDs.  iwlist must be accessible to the nagios user. 
#
# Changes and Modifications
# =========================
# 15=Jul-2011 - David Shivak
#

require 5.004;
use POSIX;
use strict;
use warnings;
use FindBin qw($Bin);
use lib "$Bin/../perl/lib", "/usr/local/nagios/libexec";
use utils qw($TIMEOUT %ERRORS &print_revision &support &usage);

use Nagios::Plugin;
use Nagios::Plugin::Getopt;

my $checkname = "check_wireless_ssid";

my ($np) = Nagios::Plugin->new(
    shortname => $checkname,
    timeout   => $TIMEOUT,
);

my ($ng) = Nagios::Plugin::Getopt->new(
    usage =>
        "Usage: %s -d <wifi device> -s <ssid> [--help] [--version]\n",
    version => '0.1',
    blurb   => 'Perl Check Wireless SSID plugin for Nagios',
    extra => 'Requires that nagios user has access to iwlist',
    license => 'Copyright (c) 2000 Michael Anthon/Karl DeBisschop, (c) 2010 David Shivak',
);

$ng->arg(
    spec     => 'device|d=s',
    help     => "Wireless device name without /dev prefix",
    required => 1,
);

$ng->arg(
    spec     => 'ssid|s=s',
    help     => "SSID to look for",
    required => 1,
);

$ng->getopts();

my ($device)      = $ng->device;
my ($ssid)     = $ng->ssid;

my ( $verbose, $warn, $crit );

$ENV{'PATH'}     = '';
$ENV{'BASH_ENV'} = '';
$ENV{'ENV'}      = '';


my $iwlist = "/usr/local/bin/iwlist";

if ( !$iwlist || !-x $iwlist ) {
    $np->nagios_die("$iwlist is not findable/executable by the Nagios user");
}

# sanitize options that will be passed to shell
$device      = quotemeta($device);
$ssid        = quotemeta($ssid);

# Does this device exist on the system?
# Iwconfig takes forever to return a nonexistent device, use proc instead
my $deviceok = 0;
open DEVLIST, "</proc/net/dev";
my @devices = <DEVLIST>;
close DEVLIST;
my $devname = "";
my $devline = "";
foreach my $devline (@devices)
	{
	($devname) = $devline =~ /(\w+):/;
	$devname = "" unless defined($devname);
	if ($devname eq $device)
		{
		$deviceok = 1;
		} 
	}
unless ($deviceok)
	{
	warn "Device $device does not exist";
	print "SSID CRITICAL: No such device $device on system";
	exit;
	}

open (IWLIST, "-|") 
       or exec ($iwlist, $device, "scan");
my @output = <IWLIST>;
close IWLIST;

my (@ssid_list) = grep {/SSID:/} @output;
my (@ssid) = grep {/$ssid/i} @ssid_list;

my $output;
my $state  = "CRITICAL";
if (scalar(@ssid) > 0)
	{
	$state = "OK";
	}

if ($state eq "OK")
	{
	$output = "SSID $state: Device $device found ssid:'$ssid' ";
	}
else	{
	$output = "SSID $state: Device $device could not find ssid:'$ssid' ";
	}

print $output;

# Just in case of problems, let's not hang Nagios
$SIG{'ALRM'} = sub {
    $np->nagios_exit( $ERRORS{'CRITICAL'}, "Wireless scan not completed" );
};
alarm($TIMEOUT);
#Turn off alarm
alarm(0);

#Split $res into an array of lines
# did we get a number back or a string?
my ($EXIT) = ( $state =~ /^\d$/ ) ? $state : $ERRORS{$state};
my $answer = 0; # CHECK THIS FOR CORRECTNESS
$np->nagios_exit( $EXIT, $answer );