#!/usr/bin/perl 

$VERSION = 0.1;

use Fcntl;
use Net::DNS;
use Net::DNS::Nameserver;
#use LWP::Simple;
use LWP::UserAgent;
use Time::HiRes qw ( usleep gettimeofday );
use MIME::Base64;
use MIME::Base32 qw ( RFC );
use IO::Socket;
use Class::Struct;
use threads;
use threads::shared;
use Thread::Queue;
use Getopt::Long;
use English;


my %opts;
my %mods;

$opts{ptrname} =  "127.0.0.1";
$opts{filename} = "nomde.pl";
$opts{forward}  = "sshdns:127.0.0.1:22";
GetOptions(
	"ip=s"   =>  \$opts{ip},
	"filename=s"  =>  \$opts{file},
    "ptrname"     =>  \$opts{ptrname},
    "Localforward"=>  \$opts{forward}
);
if($ARGV[0]) {
   $opts{localname} = $ARGV[0];
   my @tmp = split('\.', $opts{localname});
   $opts{nameoffset} = $#tmp;
   undef @tmp;
}

if(!length($opts{localname}) || !length($opts{ip})){

   print STDERR << "EOD";
nomde $VERSION:     Experimental DNS Server
Component of:  OzymanDNS          Dan Kaminsky(dan\@doxpara.com)
       Usage:  nomde -l 10.0.1.11 servername.foo.com
     Options:  -i [ip address]:   IP address to host for all A requests
               -f [filename]  :   Filename to host in TXT records [b64]
               -p [name]      :   Name/IP to return for reverse lookups[ptr]
               -L [name:host:port]: Forward function to address, port
                                    (Default:  sshdns:127.0.0.1:22)
EOD
   exit 1;
}

struct ( dns_sock => {
	sock     => '$',
	lasttime => '$',
	reader   => '$',
	queue    => '$'
});


struct ( dns_sock_data => {
	data      => '$',
	lasttime  => '$'
});

# set STDIN to nonblock
$flags='';
fcntl(STDIN, F_GETFL, $flags) or die "1\n";
$flags |= O_NONBLOCK;
fcntl(STDIN, F_SETFL, $flags) or die "2\n";


#use strict;
#use warnings;

$dataclean;

sub reply_handler {
        my ($qname, $qclass, $qtype, $peerhost, $header, $packet) = @_;
        my ($rcode, @ans, @auth, @add, $val);
	
	my @namelist = split(/\./, $qname);
	my @reverselist = reverse(@namelist);
	my $function = $reverselist[$opts{nameoffset}+1];
	my @args = (@reverselist[$opts{nameoffset}+2..$#reverselist]);

	$rcode = "NXDOMAIN";

	if ($qtype eq "AAAA") { $rcode = "NOTIMPL"; goto end;};
	if ($qtype eq "SOA") {
		my $now = gettimeofday(); # yeah that'll give unique serials
		my $name = $opts{localname};
                my ($ttl, $rdata) = (3600, "ns.$name root.$name $now 28800 14400 3600000 0");
                push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype $rdata");
                $rcode = "NOERROR";
		goto end;
        }
	if ($qtype eq "TYPE38") { $rcode = "NOTIMPL"; goto end;};
	if ($qtype eq "A" && $function eq "glance") {
		my $addr = $args[0];
		chomp($addr);
		$addr =~ s/_/\./g;
		$addr =~ s/-/\//g;
		$addr = "http://" . $addr;

		my $ua      = LWP::UserAgent->new;
		my $request = HTTP::Request->new(HEAD => "$addr");
		my $response= $ua->request($request);
		my $modified_time = $response->last_modified;
		my $expires       = $response->expires;
		my $date          = $response->date;

		my $ttl     = $expires - $date;
		
		my @array = unpack("C*", pack("V", $modified_time));  # will it work? 
		my $nsip = join(".", @array);
		if ($ttl < (60*20)) {$ttl = 60*20;}
		push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype $nsip");
		$rcode = "NOERROR";
		goto end;
	}
	if ($function eq "echo"){
	
    	if ($qtype eq "A" && $namelist[0] eq "ns")
    	{
    		my $nsip = $args[0];
    		$nsip =~ s/-/./g;
    		my ($ttl, $rdata) = (20, $nsip);
    		push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype $rdata");
    		$rcode = "NOERROR";
    		goto end;
    	}
    	else {
    		my $nsip = $args[0];
    		$nsip =~ s/-/./g;
    		my $ns = "ns." . "$qname";
    		print "\n$ns\n";
    		$type = "NS";
    		if($qtype eq "NS") {
        		push @ans, Net::DNS::RR->new("$qname 20 $qclass NS $ns");
    		} else {
                push @auth, Net::DNS::RR->new("$qname 20 $qclass NS $ns");
            }
    		push @add, Net::DNS::RR->new("$ns 20 $qclass A $nsip");
    		$rcode = "NOERROR";
    		goto end;
    	}
	}
    

	if ($qtype eq "CNAME") { $rcode = "NOERROR"; goto end;};
	if ($qtype eq "PTR") {
		my ($ttl, $rdata) = (0, $opts{ptrname});
		push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype $rdata");
                $rcode = "NOERROR";
	}
	if ($qtype eq "TXT" && $function eq "b64" && $opts{file}) {
		my $val, $i;
		seek($opts{file}, $args[0], 0);
		read($opts{file}, $val, 57*2);
		$val = encode_base64($val);
		read($opts{file}, $val2, 57*2);
		$val2 = encode_base64($val2);
		my $ttl = 60;
		push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype \"$val\" \"$val2\"" );
                $rcode = "NOERROR";
		goto end;
	}

    my ($servname, $remotehost, $remoteport) = split(":", $opts{forward});
	if ($function eq "$servname"){
	   my $op     = $args[0];
	   my $id     = $args[1];
	   my ($offset, $nonce) = split("-", $args[2]);
	   
	   my $now = gettimeofday();
	   if(!$sockclean || $now - $sockclean > 240){
	       $sockclean = gettimeofday();
	       foreach $scanid (keys %socklist){
	          if($now - $socklist{$scanid}->lasttime > 10){
	             $socklist{$scanid}->sock->shutdown(2);
		     delete $socklist{$scanid};
	          }
	       }
	   }
       my $scanid;
	   if(!$dataclean || $now - $dataclean > 20){
	       $dataclean = gettimeofday();
	       foreach $scanid (keys %sockdata) {
	          if(defined($sockdata{"$scanid"})&&
	              $now - $sockdata{"$scanid"}->lasttime > 60){
	             delete $sockdata{$scanid};
	          }
           }
       }
	       
	   if(!exists $socklist{$id}) {
	         $socklist{$id}=new dns_sock;
	         my $sock = IO::Socket::INET->new(
	            PeerAddr => "$remotehost",
		        PeerPort => "$remoteport",
	            Proto    => "tcp",
		        Type     => SOCK_STREAM,
	            Blocking => 1);# or die "couldn't spawn socket\n";
		 $socklist{$id}->queue(Thread::Queue->new);
         $socklist{$id}->sock($sock);
		 $socklist{$id}->reader(threads->new(\&reader, $socklist{$id}->sock, $socklist{$id}->queue));
	   }

	   $socklist{$id}->lasttime($now);
	   my $sock = $socklist{$id}->sock;

	   my $sockdata_is_fresh=0;
	   if(!exists $sockdata{$op,$offset,$id}) {
	         $sockdata{$op,$offset,$id} = new dns_sock_data;
	         $sockdata{$op,$offset,$id}->lasttime($now);
	         $sockdata_is_fresh=1;
	   }

	   my $data = $sockdata{$op,$offset,$id}->data;
	   if($op eq "up" && $qtype eq "A"){
	      my $size=0;
	      $data = uc join("", reverse(@args[3..$#args]));
	      $data = MIME::Base32::decode($data);

	      if($sockdata_is_fresh){
	         while($size != length($data)) {
		    my $outdata;
		    $outdata = substr($data, $size);
	            $size += syswrite($sock, $outdata, length($data)-$size);
		    if($size != length($data)){usleep (100 * 1000);}
	         }
	         $data="1"; #for now, we don't store incoming data
	      }
	      $sockdata{$op,$offset,$id}->data($data);
	      my $reply = "$size.0.0.0";
	      my $ttl  = 0;
	      push @ans, Net::DNS::RR->new("$qname $ttl $qclass A $reply");
	      $rcode = "NOERROR";
	     
	      goto end;
	   }

	   sub reader {
		my @args = @_;
		my $sock = @args[0];
		my $queue= @args[1];
	
		while(1){
		   if($queue->pending < 32) {
			sysread($sock, $data, 220);
			if(length($data)) {$queue->enqueue($data);}
			usleep (50 * 1000 / 10);
		   }
		}
	   }

	   if($op eq "down"){ #intentionally not txt checking
	      if($sockdata_is_fresh || length($data)==0) {
		 $data = $socklist{$id}->queue->dequeue_nb;
	         #sysread($sock, $data, 220);
	      }
	      $sockdata{$op,$offset,$id}->data($data);
	      my $data1  = substr($data, 0, 110);
	      my $data2  = substr($data, 110, 110);
	      my $txt1 = encode_base64($data1);
	      my $txt2 = encode_base64($data2);
	      my $x    = $socklist{$id}->queue->pending;
	     
	      push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype \"$txt1\" \"$txt2\"");
	      push @add, Net::DNS::RR->new("pending.$qname $ttl $qclass A $x.0.0.0");
	      $rcode = "NOERROR";
	      goto end;
	   }
	}

	if ($function eq "b32" && $args[0] eq "set") {
		my $descrip = $args[1];
		my @data = @args[2..$#args];
		my $string = join(".", @data);
		#my $data   = MIME::Base32::decode($string);
		$datastore{$descrip} = $qname; #$string;
		push @ans, Net::DNS::RR->new("$qname $ttl $qclass   A 1.0.0.0");
		#push @ans, Net::DNS::RR->new("$qname $ttl $qclass TXT \"ok: $descrip = $string\"");
		$rcode = "NOERROR";
		goto end;
	}
	if ($function eq "b32" && $args[0] eq "get") {
		my $descrip = $args[1];
		if(exists $datastore{$descrip}){
		   push @ans, Net::DNS::RR->new("$qname $ttl $qclass CNAME $datastore{$descrip}");
		   push @add, Net::DNS::RR->new("$datastore{descrip} $ttl $qclass     A 1.0.0.0");
		   $rcode = "NOERROR";
		} else {
		   $rcode = "NXDOMAIN";
		}
		goto end;
	}
		
        if ($qtype eq "TXT") {
		$val = `/bin/date`;
		chomp $val;
		$val = "Hi:  $val";
                my ($ttl, $rdata) = (0, $val);
                push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype \"$rdata\"");
                $rcode = "NOERROR";
		goto end;
	}
	if ($qtype eq "NS") {
        if($args[0] ne "ns"){ my ($ttl, $rdata) = (3600, "ns.$name");}
        push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype $rdata");
		push @add, Net::DNS::RR->new("$qname $ttl $qclass $qtype $opts{ip}");
                $rcode = "NOERROR";
		goto end;
        }
		

        if ($qtype eq "A") {
                my ($ttl, $rdata) = (3600, $opts{ip});
                push @ans, Net::DNS::RR->new("$qname $ttl $qclass $qtype $rdata");
                $rcode = "NOERROR";
		goto end;
        }

	end:
	my $element, $name;
	print "\n";
	foreach $element (@ans, @auth, @add) {
		$name = $element->string;
		chomp $name;
		print $name, "\n";
	}

        # mark the answer as authoritive (by setting the 'aa' flag
        my @response = ($rcode, \@ans, \@auth, \@add, { aa => 1 });
	return @response;
}
if(length($opts{filename})) {open FILE, "$opts{filename}" or die $!;}
binmode FILE;
$opts{file}=FILE;

my %datastore;

# note that this socket is blocking -- WAY harder to do nonblocking with
# callbacks (need fork/ipc).
my %socklist : shared;
%sockdata;

my $ns = Net::DNS::Nameserver->new(
    LocalPort    => 53,
    ReplyHandler => \&reply_handler,
    Verbose      => 2,
) || die "couldn't create nameserver object\n";

$ns->main_loop;