Shell Programming and Scripting

#use strict;
use Getopt::Long;
use utils qw(%ERRORS);
use vars qw($opt_V $opt_h $opt_H $opt_w $opt_c $warning $critical);


my $PROGNAME = "check_dns";
my $VERSION = "Beta 1";
my $query = "/usr/bin/host";

sub messages();

Getopt::Long::Configure('bundling');
GetOptions
        ("V"   => \$opt_V, "version"    => \$opt_V,
         "h"   => \$opt_h, "help"       => \$opt_h,
         "q=s" => \$opt_q, "query=s" => \$opt_q,
         "s=s" => \$opt_s, "server=s" => \$opt_p,
         "e=s" => \$opt_e, "expected=s" => \$opt_e);


messages();
if ($opt_V) { print $Messages{Version} and exit $ERRORS{'UNKNOWN'}; }
if ($opt_h) { print $Messages{Usage} and exit $ERRORS{'UNKNOWN'}; }
print $Messages{Files} and exit unless (-x $query);
unless ($opt_q && $opt_s) { print $Messages{Usage} and exit $ERRORS{'UNKNOWN'}; }
my $response = `$query $opt_q $opt_s`;
my @response = split('\n', $response);
my @expected = split(',', $opt_e);
my $success = '';
my $fail = '';
my $critical = '';
my $timeout = '';
messages();
@expected = sort(@expected);
IP: foreach my $ip (@expected) {
        my $found = 0;
        foreach (@response) {
        print $Messages{'Timeout'} and exit $ERRORS{'CRITICAL'} if /connection timed out/;
        print $Messages{'Failure'} and exit $ERRORS{'CRITICAL'} if /not found/;
        #$found = 1 and last if /$opt_q has address $ip/; # This doesnt work because the 'host' command resolves the query string to it's alias
        $found = 1 and last if /has address $ip/;
        }
        $success .= "$ip, " if $found;
        $fail .= "$ip, " unless $found;
}
chop $success && chop $success;
chop $fail && chop $fail;
messages();
print $Messages{'Warning'} and exit $ERRORS{'WARNING'} if $fail;
print $Messages{'Ok'} and exit $ERRORS{'OK'} if $success;
print "Unknown Output\n" and exit;

sub messages () {
%Messages = (   'Files'         => "make sure $query exists and is executable.\n",
                'Timeout'       => "Connection Timed Out, DNS Unavailable!.\n",
                'Failure'       => "Critical: $opt_s returned $opt_q not found.\n",
                'Version'       => "$PROGNAME Version: $VERSION\n",
                'Ok'            => "Ok: $opt_s returned $success on query for $opt_q.\n",
                'Warning'       => "Warning: $opt_s did not return $fail on query for $opt_q.\n",
                'Usage'         => "Usage: $PROGNAME -s <server> -q <query> -e <expected>\n"
                                        ."\t<server> = DNS Server to query\n"
                                        ."\t<query> = DNS record to query\n"
                                        ."\t<expected> = comma seperated lists of expected IP's\n" );
}