Hey everyone, just wanted to post some code to have it reviewed. 




#!/usr/bin/perl 
use Net::DNS::Resolver;
use NetAddr::IP;

use vars qw/ %opt /;

######################################################################
+###################
#                                            #
#    Sub to perform DNS lookup                            #
#    Too lazy to write one sub with var for fw/rev so did two instead 
+       #
#                                            #
######################################################################
+###################
sub revlookup
{
    my $res=Net::DNS::Resolver->new;
    $res->nameservers($server);
    my $search = $res->search($input);
    
    if ($search)
    {
        foreach $rr ( $search->answer)
        {
            my $type=$rr->type;
            if ($type eq "A")
            {
                $host=$rr->address;
            }
            if ($type eq "PTR")
            {
                $host=$rr->ptrdname;
            }
            else
            {
                print "$input\t$rr->type\n";
            }
        #print "$input\t$host\n";
    push(@reverseip,$input);
    push (@reversename, $host);
        }
    }
}

sub fwlookup
{
    my $res=Net::DNS::Resolver->new;
    $res->nameservers($server);
    my $search = $res->search($input);
    
    if ($search)
    {
        foreach $rr ( $search->answer)
        {
            my $type=$rr->type;
            if ($type eq "A")
            {
                $host=$rr->address;
            }
            if ($type eq "PTR")
            {
                $host=$rr->ptrdname;
            }
            if ($type eq "CNAME")
            {
                $host=$rr->cname;
            }
            else
            {
                #print "$input\t$rr->type\n";
            }
        #print "$input\t$host\n";
    push(@forwardip,$host);
    push (@forwardname, $input);
        }
    }
    else
    {
        push (@forwardip, $res->errorstring);
        push (@forwardname, $input);
    }
}

######################################################################
+###################
#                                            #
#    sub to check command line options passed to program for validity 
+       #
#                                            #
######################################################################
+###################
sub options
{
    use Getopt::Long;
    if ($#ARGV lt 0)
    {
        &usage;
    }
    GetOptions ("r:s"     => \$cidr,
            "h"     => \$help,
            "s:s"    => \$server);
    &usage if $help;    
    &usage if not $cidr;
    &usage if not $server;
}


######################################################################
+###################
#                                            #
#    sub to display a usage message                            #
#                                            #
######################################################################
+###################
sub usage
{
    print "-h help message\n";
    print "-r [range] to search in CIDR format: 128.0/8\n";
    print "-s [server] to direct queries to\n";
    exit 1;
}


######################################################################
+###################
#                                            #
#    Main program                                    #
#    Too lazy to write sub to do check so just shoved it in here      
+      #
#                                            #
######################################################################
+###################
&options;

my $ip = new NetAddr::IP($cidr);
$range = $ip->range();
$bcast = $ip->broadcast();
print "Searching range: $range: Broadcast $bcast\n";
while ($ip < $ip->broadcast)
{
    ($iponly,$mask) = split /\//, $ip;
    $input=$iponly;
    &revlookup;
    $ip++;
}

foreach (@reversename)
{
   $input=$_;
   &fwlookup;
}


for ($count=0; $count ne $#reversename; $count++)
{
    $revip=$reverseip[$count];
    $revname=$reversename[$count];
    $fwip=$forwardip[$count];
    $fwname=$forwardname[$count];

    if ($revip ne $fwip)
    { 
        print "\n\n";
        print "REVERSE: $revip\t$revname\n";
        print "FORWARD: $fwname\t$fwip\n";
    }
    if ($fwname ne $revname)
    {
        print "\n\n";
        print "WARNING: $revname\t$fwname\n";
    }
}

[download]


I know it's not the best in the world, but it sort of works.

My question is: would it be better to have a variable passing to a lookup sub to say "this is forward" or "this is reverse"
I know that there is unnecessary use of too many arrays here



Anyway, any comments appreciated.




Thanks for the feedback everyone.I'll probably post another updated version in a week or so when I get time to update it.....
comments much appreciated.

In reply to code review by svankalken

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