PERL - Mass A Record IPv4 to IPv6 Replacement

# Copyright notice. 
# Please include this in redistribution.
# Original author kevinhng86 @ FAI Hosting Solution.
# This is free to use for any purpose that is not unlawful for free of charge.
# This script follow CDDL-1.0 license protocol, to use this script for any purpose you are agreeing to CDDL-1.0.
# CDDL-1.0 license can be view from the link below.
# https://opensource.org/licenses/CDDL-1.0

use strict;

package config;
    our $dir = "./yourdir"; #directory to look into to search for DNS name file record file
    our $ext = "ns"; #extension of file, dont put dot here
    our $ipv4 = "123:123:123:123"; #ipv4 address to look for
    our $ipv6 = "2001:db8:3:4::1"; #ipv6 address to change or replace to
    our $tempdir = "./tmp"; #temporary directory


package function;
sub getFileList{
  our ($getdir, $getname) = @_; # to use this function string directory path first, string extension after
    our @list = ();  # array to hold all file name with the config extenstion
    our @output = (); # output array
    
    # Open directory and search for file with extension, compile an array with all file names that is found
    opendir my $DIR,  $getdir or die "Cannot open directory: $!"; 
    @list = grep( /\.$getname$/ ,readdir($DIR));
    closedir($DIR);

    # If directory name input doesn have / then add / to the end of it
    if (!($getdir =~ /\/$/)) { $getdir = $getdir . "/";};
    

    # Add file name to full path for each file is found and push the result into an output array.
    for (our $i = 0; $i < scalar(@list); $i++){
        our $str = $getdir . @list[$i];
        push @output, $str;
    }
    
    # This function can return 2 result, the array @list is for filename only, array @output is file name with full path, configure to desire
    return @output;
}


sub faiIPv4ToIPv6{
    our ($inarray, $ipv4, $ipv6, $tempdir, $operation) = @_;
    our @filelist = @{ $inarray };
    our @repcountarr = (); # storing information
    our %repcounthash = {}; # storing how many record is replace from a file into a hash;
    our $repcount = 0; # each time a row is replace with record count will increase
    our $tempfile = "faitemp.tmp"; # temporary file name
    our $tempstr = ""; # Temporary string to work with, for operation replace
    our $tempstradd = ""; # Temporary sring for operation add
    our $tempdirexist = ""; #variable to check if temporary directory pre-exist for script clean up

    # check operation, only support add or replace
    if ($operation ne "add" && $operation ne "replace") { die "only support operation add or replace"  } ;
    
    # create a string with temp file full path, first check to see if there is a splash on the end of temp dir if there is not add a splash
    if (!($tempdir =~ /\/$/)) { $tempdir = $tempdir . "/";};
    our $tempfullpath = $tempdir . $tempfile;
    
    
    # check if temp dir is exist if not create, set tempdirexist in both case for clean up after 
    if (-d $tempdir){
        $tempdirexist = "true";
    }
    if (!-d $tempdir){
        $tempdirexist = "false";
        unless(mkdir $tempdir) {
             die "Unable to create $tempdir\n";
        }
    }
    
    if (-e $tempfullpath) {
        die "temporary file $tempfullpath exist.\nYou might have another program use the same name or this script crash while running, check to see if any information is needed\n";
    }
    
    
    for ( our $i = 0; $i < scalar(@filelist); $i++){
            $repcount = 0; # Set replace count to 0 each time one file is loop through
            %repcounthash = {}; # Reset all rep count hash property after every use.
            our @content = () ; # Read content into this array, each line equal to one array 
            our $arrcount = 0; # everytime a newline is read from the file this count will plus one so array does not save to the same one everytime
            our @contentadd = (); # when adding temporary save onto this array
            our $arraddcount = 0; # everytime there is a modification to the add array this have to be increase

            # open file and read all content into an array
            open(ORGIN, "<"."@filelist[$i]") or die "Could not open file '@filelist[$i]' $!" ;
                while (our $row = <ORGIN>){
                    chomp($row);
                    @content[$arrcount] = $row;
                    $arrcount = $arrcount + 1;
                }
            close(ORGIN);
            
            
            
            # This is simple, if replace just replace the ipv4 with ipv6 and replace A with AAAA
            if ($operation eq "replace" ){
                for (our $id = 0; $id < scalar(@content); $id++){
                    if ( index(@content[$id], $ipv4) != -1 && index(@content[$id], "A"  ) != -1 ){
                         @content[$id] =~ s/$ipv4/$ipv6/g;
                         @content[$id] =~ s/A/AAAA/g;
                         $repcount = $repcount + 1;
                    }
                }
            }
            
            
            # Operation add, check if there is ipv4 value. If match check to see if weather an ipv6 record exist for ipv4 record.
            # Only add if there is not another ipv6 record with same value exist.
            # append the information to a difference array so that the record are add below the original record.
            if ($operation eq "add"){
                for (our $id = 0; $id < scalar(@content); $id++){
                    @contentadd[$arraddcount] = @content[$id];
                    $arraddcount = $arraddcount + 1;
                    if ( index(@content[$id], $ipv4  ) != -1 && index(@content[$id], "A"  ) != -1 ){
                         $tempstr = @content[$id];
                         $tempstr =~ s/$ipv4/$ipv6/g;
                         $tempstr =~ s/A/AAAA/g;
                         if ( !(grep { $_ eq $tempstr} @content) ){
                             $repcount = $repcount + 1;
                             @contentadd[$arraddcount] = $tempstr;
                             $arraddcount = $arraddcount +1;
                         }
                    }
                }
                @content = @contentadd;
            }
           
            # Open a temporary file to write to and then copy that file to the original just read from.
            # This way we do not open the original again incase script failure during write, crash, or unexpected program behaviour on difference platform.
            open(TEMP, ">"."$tempfullpath") or die "Could not open file '$tempfullpath' $!";
                for (our $id = 0; $id < scalar(@content); $id++){
                    print TEMP @content[$id] . "\n";
                }
            close( TEMP );
            
            # Replace the original file with a temp file. 
            rename ($tempfullpath, @filelist[$i] );

            # produce how many records was replace or add in which file.    
            $repcounthash{"operation"} = $operation;
            $repcounthash{"count"} = $repcount;
            $repcounthash{"file"} = @filelist[$i];        
            push @repcountarr, {%repcounthash};


    }
    
    # if the temp directory was created by this script delete it, if not left it intact
    if ( $tempdirexist eq "false" ){
        rmdir $tempdir;
        if(-e $tempdir) 
        {
            print "Temporary directory '$tempdir' could not be deleted";
        }
    }
    
    return @repcountarr;
    
}



package main;

our @test = function::getFileList($config::dir, $config::ext);
our @result = function::faiIPv4ToIPv6([@test], $config::ipv4, $config::ipv6, $config::tempdir, "add");

for (our $i = 0; $i < scalar(@result); $i++){
    if (  @result[$i]->{"operation"} eq "replace"){
    print @result[$i]->{"operation"} . " " . @result[$i]->{"count"} . " record(s) from " . @result[$i]->{"file"} . "\n";
    }
    
    if (  @result[$i]->{"operation"} eq "add"){
    print @result[$i]->{"operation"} . " " . @result[$i]->{"count"} . " record(s) to " . @result[$i]->{"file"} . "\n";
    }
}