#!/usr/bin/env perl

use strict;
use warnings "all";

use Net::DNS;
use threads;
use threads::shared;

my $max_sleep = 2000;         # max sleep between sequental lookups 2 seconds long
my $max_burst_lookups = 15;   # max amount of lookup without delay
my $threads_max = 310;        # on my vm threads gonna die if amount more than 313, seems like some pthread limit?
my @nameservers = ('192.168.88.2');

my $domfile = 'domfile.txt';  # file format: domainname record_type number_of_values
                              # num_of_values can be -1 if no A record exist
sub worker;                   # main sub of worker
sub lookup;                   # hotpath :)
sub nodomlist;
sub usleep;                   # millisecond sleep, 1000 milliseconds = 1 second

nodomlist() unless ( -f $domfile );

my $res;

my @list;
open (LIST, $domfile) or die ("Unable to read $domfile");

while (<LIST>){
	next if (($_ eq '') or ($_ =~ /^\s*#/));
	chomp($_); chomp($_);
	push @list, $_;
}

close LIST;

# TODO: looks like this stuff should be created on per thread basis, not shared

my @threads;
for (my $m = 1; $m <= $threads_max; $m++){
	push @threads, threads->create('worker');
	syswrite STDOUT, "thread $m/$threads_max spawned\r";
	usleep('10');
}

syswrite STDOUT, "\n";

# we'll wait forever 'till threads' exit :)
foreach my $thread (@threads){ $thread->join(); }

exit 0;


sub worker {
	threads->yield();

	$res = Net::DNS::Resolver->new(
		nameservers => [ @nameservers ],
		recurse     => 1,
		debug       => 0
	);

	my $lookup_cnt = int(rand($max_burst_lookups));
	while ( 1 ) {
		my $ok = 0; my $error = 0;

		for (my $i = 0; $i < 10000; $i++) {

			if ($lookup_cnt <= 0){
				usleep(int(rand($max_sleep)));
				$lookup_cnt = int(rand($max_burst_lookups));
			} else {
				$lookup_cnt--;
			}

			my ($domain, $record_type, $amount) = split(/\s+/, $list[int(rand(@list))]);
			my $result = lookup($domain, $record_type);

			if (defined($result) and ($result == $amount)){ $ok++; }
			elsif (($amount == -1) and ($result == undef)){ $ok++; }
			else { $error++; }
		}

		syswrite STDOUT, "Success/Error: $ok/$error\n";
	}
	return 0; # we'll never return :(
}

sub lookup {
	my $host = shift;
	my $type = shift;
	my $rec_count = 0;
	my $reply = $res->query($host, $type);

	if (defined($reply)) {

		foreach my $rr ($reply->answer) {
			$rec_count++ if ($rr->type eq $type);
		}

		return $rec_count;
	} else {
#		warn "query failed: ", $res->errorstring, "\n";
		return undef;
	}
}

sub nodomlist {
	print "Unable to find $domfile\n";
	exit 1;
}

sub usleep {
	my $delay = shift;
	select(undef, undef, undef, $delay/1000);
	return;
}