# Supports ranges in any number of bytes.

sub parse_ip_mask {
   my ($ip_mask) = @_;
   my $checks = '';
   my $check_num = 0;
   my $ip_re = join('\\.', map {
      if (/\[(\d+)-(\d+)\]/) {
         $check_num++;
         $checks .= " && \$$check_num >= $1";
         $checks .= " && \$$check_num <= $2";
         '(\\d+)'
      } else {
         $_
      }
   } split(/\./, $ip_mask));
   return eval "sub { (\$_[0] || \$_) =~ /^$ip_re\$/$checks }";
}

my $ip_check = parse_ip_mask('131.202.1.[3-4]');

foreach (qw(
   131.202.1.2
   131.202.1.3
   131.202.1.4
   132.202.1.4
)) {
   print(&$ip_check()   # Uses $_ if no arguments are specified.
      ? "$_ matches.$/"
      : "$_ doesn't match.$/"
   );
}

__END__
output
======
131.202.1.2 doesn't match.
131.202.1.3 matches.
131.202.1.4 matches.
132.202.1.4 doesn't match.