#!/usr/bin/perl

$auth_enabled = 0;
$auth_login = "user";
$auth_pass = "pass";
$port = 3003;

use IO::Socket::INET;

$SIG{'CHLD'} = 'IGNORE';
$bind = IO::Socket::INET->new(Listen=>10, Reuse=>1, LocalPort=>$port) or  die "Can't bind port $port\n";

while($client = $bind->accept()) {
$client->autoflush();

if(fork()){ $client->close(); }
else { $bind->close(); new_client($client); exit(); }
}

sub new_client {
local $t, $i, $buff, $ord, $success;
local $client = $_[0];
sysread($client, $buff, 1);

if(ord($buff) == 5) {
  sysread($client, $buff, 1);
  $t = ord($buff);

  unless(sysread($client, $buff, $t) == $t) { return; }

  $success = 0;
  for($i = 0; $i < $t; $i++) {
    $ord = ord(substr($buff, $i, 1));
    if($ord == 0 && !$auth_enabled) {
      syswrite($client, "\x05\x00", 2);
      $success++;
      break;
    }
    elsif($ord == 2 && $auth_enabled) {
      unless(do_auth($client)){ return; }
      $success++;
      break;
    }
  }

  if($success) {
    $t = sysread($client, $buff, 3);

    if(substr($buff, 0, 1) == '\x05') {
      if(ord(substr($buff, 2, 1)) == 0) { # reserved
        ($host, $raw_host) = socks_get_host($client);
        if(!$host) {  return; }
        ($port, $raw_port) = socks_get_port($client);
        if(!$port) { return; }
        $ord = ord(substr($buff, 1, 1));
        $buff = "\x05\x00\x00".$raw_host.$raw_port;
        syswrite($client, $buff, length($buff));
        socks_do($ord, $client, $host, $port);
      }
    }
  } else { syswrite($client, "\x05\xFF", 2); };
}
$client->close();
}

sub do_auth {
local $buff, $login, $pass;
local $client = $_[0];

syswrite($client, "\x05\x02", 2);
sysread($client, $buff, 1);

if(ord($buff) == 1) {
  sysread($client, $buff, 1);
  sysread($client, $login, ord($buff));
  sysread($client, $buff, 1);
  sysread($client, $pass, ord($buff));

  if($login eq $auth_login && $pass eq $auth_pass) {
    syswrite($client, "\x05\x00", 2);
    return 1;
  } else { syswrite($client, "\x05\x01", 2); }
}

$client->close();
return 0;
}

sub socks_get_host {
local $client = $_[0];
local $t, $ord, $raw_host;
local $host = "";

sysread($client, $t, 1);
$ord = ord($t);
if($ord == 1) {
  sysread($client, $raw_host, 4);
  @host = $raw_host =~ /(.)/g;
  $host = ord($host[0]).".".ord($host[1]).".".ord($host[2]).".".ord($host[3]);
} elsif($ord == 3) {
  sysread($client, $raw_host, 1);
  sysread($client, $host, ord($raw_host));
  $raw_host .= $host;
} elsif($ord == 4) {
  #ipv6 - not supported
}

return ($host, $t.$raw_host);
}

sub socks_get_port {
local $client = $_[0];
local $raw_port, $port;
sysread($client, $raw_port, 2);
$port = ord(substr($raw_port, 0, 1)) << 8 | ord(substr($raw_port, 1, 1));
return ($port, $raw_port);
}

sub socks_do {
local($t, $client, $host, $port) = @_;

if($t == 1) { socks_connect($client, $host, $port); }
elsif($t == 2) { socks_bind($client, $host, $port); }
elsif($t == 3) { socks_udp_associate($client, $host, $port); }
else { return 0; }

return 1;
}

# this part of code was taken from datapipe.pl utility,
# written by CuTTer (cutter[at]real.xakep.ru)
# utility lays on cpan.org

sub socks_connect {
my($client, $host, $port) = @_;
my $target = IO::Socket::INET->new(PeerAddr => $host, PeerPort => $port, Proto => 'tcp', Type => SOCK_STREAM);

unless($target) { return; }

$target->autoflush();
while($client || $target) {
  my $rin = "";
  vec($rin, fileno($client), 1) = 1 if $client;
  vec($rin, fileno($target), 1) = 1 if $target;
  my($rout, $eout);
  select($rout = $rin, undef, $eout = $rin, 120);
  if (!$rout  &&  !$eout) { return; }
  my $cbuffer = "";
  my $tbuffer = "";

  if ($client && (vec($eout, fileno($client), 1) || vec($rout, fileno($client), 1))) {
    my $result = sysread($client, $tbuffer, 1024);
    if (!defined($result) || !$result) { return; }
  }

  if ($target  &&  (vec($eout, fileno($target), 1)  || vec($rout, fileno($target), 1))) {
    my $result = sysread($target, $cbuffer, 1024);
    if (!defined($result) || !$result) { return; }
    }

  if ($fh  &&  $tbuffer) { print $fh $tbuffer; }

  while (my $len = length($tbuffer)) {
    my $res = syswrite($target, $tbuffer, $len);
    if ($res > 0) { $tbuffer = substr($tbuffer, $res); } else { return; }
  }

  while (my $len = length($cbuffer)) {
    my $res = syswrite($client, $cbuffer, $len);
    if ($res > 0) { $cbuffer = substr($cbuffer, $res); } else { return; }
  }
}
}

sub socks_bind {
my($client, $host, $port) = @_;
# not supported
}

sub socks_udp_associate {
my($client, $host, $port) = @_;
# not supported
}