I recommend using NetAddr::IP to make your life much easier, and your code more readable.

from the docs:

use NetAddr::IP;
  my $ip = new NetAddr::IP 'loopback';
  if ($ip->within(new     NetAddr::IP "127.0.0.0", "255.0.0.0")) {
      print "Is a loopback address\n";
  }
[download]

The module also has many other functions for defining and scanning subnets.