Generate IPv6 reverse DNS records for Bind

reverse6.pl

#!/usr/bin/env perl

sub populateArrayFromFile {
  my ($filename) = @_;
  open FILE, $filename || die "Cannot open file ".$filename." for read";
  @lines=<FILE>;
  close FILE;
  return @lines;
}
sub ip6AppendZeroes {
  my ($address) = @_;
  @array = split(/:/, $address);
  my $address;
  foreach $elem (@array) {
    if (length $elem > 0 && length $elem < 4) { $elem = padWithZeroes($elem);}
    elsif (length $elem == 0) { $elem = "::" }
    $address = $address.$elem;
  }
  $address = ip6ConsecutiveHexFieldReplace($address);
  $address = ip6ReverseAndSeparate($address);
  return $address;
}
sub ip6ReverseAndSeparate {
  my ($address) = @_;
  $address = reverse $address;
  @octets = split(//, $address);
  foreach my $octet (@octets) { $octet = $octet."." }
  $address =~ s/(.)/$1\./g;
  return $address;
}
sub ip6ConsecutiveHexFieldReplace {
  my ($address) = @_;
  my $pad_len = 32 - length($address);
  my $find = "::";
  my $pad_len = $pad_len + 2;  # There is an offset, caused by "::" symbol taking up space
  $find = quotemeta $find;
  my $paddedNumber = "0" x ( $pad_len );
  $address =~ s/$find/$paddedNumber/g;
  return $address;
}
sub padWithZeroes {
  my ($number) = @_;
  my $pad_len = 4 - length($number);
  my $paddedNumber = "0" x ( $pad_len ) . $number;
  return $paddedNumber;
}

# Main
foreach my $filename (@ARGV) {
  my @newlines = ();
  my @lines = populateArrayFromFile($filename);
  foreach $line (@lines) {
    if ($line =~ m/([\dA-F:]+)\s+(\S+)/) {
      my $address = ip6AppendZeroes($1);
      print $address."ip6.arpa.    IN  PTR  $2.","\n"
    }
  }
}