#!/usr/bin/perl

use strict;
use warnings;

my $temp = 'key1=two_tabs%09%09+other_two_tabs%09%09&key2=three_nulls_%00%00%00';

my @pairs = split(/&/, $temp);
foreach my $item(@pairs) {
    my ($key, $value) = split(/=/, $item, 2);
    $value =~ tr/+/ /;
    $value =~ s/%(..)/pack("c", hex($1))/ge;
    $value =~ s/\t/ /g;
    $value =~ s/\0//g;
    print "Key: '$key', value: '$value'\n";
}