#!/usr/bin/perl

use Data::Dumper;
use IO::Select;
use Net::DNS;

my $timeout = 10;
my $sel; # global IO::Select object 

my $max_resolver = 1;
my $max_sockets  = 2;
my $max_sessions = $max_resolver * $max_sockets;

my @resolvers;

push( @resolvers, Net::DNS::Resolver->new) for 1..$max_resolver;

my $resolver_counter = 0;
my $socket_counter   = 0;
my $session_counter  = 0;


my $host_counter = 0;
my %sockets = ();

local $| = 1;

while ( <> ) {
    chomp;
print "INITIAL Line: $_\n";
    if ($session_counter < $max_sessions) {
        # make a new DNS session
        my $resolver = $resolvers[ $resolver_counter ];

        my $bgsock   = $resolver->bgsend( $_, 'A' );
        $sockets{ $bgsock } = $resolver;

        if (defined $sel) {
            $sel->add( $bgsock );
        }
        else {
            $sel     = IO::Select->new( $bgsock );
        }
        ++$session_counter;
        if (++$socket_counter == $max_sockets) {
            $socket_counter = 0;
            if (++$resolver_counter == $resolver_counter) {
                $resolver_counter = 0;
            }
        }
        ++$host_counter;
        last if $session_counter == $max_sessions;
    }
    next;
}

print "OKOK \$ARGV: $ARGV\n";

while ($host_counter > 0) {
    my @ready = $sel->can_read( $timeout );
    if ( scalar @ready > 0) {
        foreach my $sock (@ready) {
            my $resolver = $sockets{ $sock };
            my $response = $resolver->bgread( $sock );
            $sel->remove($sock);
            delete $sockets{ $sock };
            --$host_counter;
print "AAAA \$ARGV: $ARGV\n";
            my $line = <>;
print "BBBB \$ARGV: $ARGV\n";
            if ($line ) {
print "ADDITIONAL Line: $line" ;
                chomp $line;
                my $new_sock = $resolver->bgsend( $line, 'A' );
                $sel->add( $new_sock );
                $sockets{ $new_sock } = $resolver;
                ++$host_counter;
print "CCCC \$ARGV: $ARGV\nHostcounter: $host_counter\n";
            }
        }
    }
    else {
        warn "\n\ntimed out after $timeout seconds\n\n";
    }
}

exit;