IO :: Socket :: Socks (source)

TABLE OF CONTENTS

NAME

IO::Socket::Socks - Provides a way to create socks client or server both 4 and 5 version.

SYNOPSIS

Client

use IO::Socket::Socks;

my $socks = new IO::Socket::Socks(ProxyAddr=>"proxy host",
                                  ProxyPort=>"proxy port",
                                  ConnectAddr=>"remote host",
                                  ConnectPort=>"remote port",
                                 );

print $socks "foo\n";

$socks->close();

Server

use IO::Socket::Socks ':constants';

my $socks_server = new IO::Socket::Socks(ProxyAddr=>"localhost",
                                         ProxyPort=>"8000",
                                         Listen=>1,
                                         UserAuth=>\&auth,
                                         RequireAuth=>1
                                        );

while(1)
{
    my $client = $socks_server->accept();

    if (!defined($client))
    {
        print "ERROR: $SOCKS_ERROR\n";
        next;
    }

    my $command = $client->command();
    if ($command->[0] == CMD_CONNECT)
    {
       # Handle the CONNECT
       $client->command_reply(REPLY_SUCCESS, addr, port);
    }
      
    ...
    #read from the client and send to the CONNECT address
    ...
    
    $client->close();
}

sub auth
{
    my $user = shift;
    my $pass = shift;

    return 1 if (($user eq "foo") && ($pass eq "bar"));
    return 0;
}

DESCRIPTION

IO::Socket::Socks connects to a SOCKS proxy, tells it to open a connection to a remote host/port when the object is created. The object you receive can be used directly as a socket for sending and receiving data from the remote host. In addition to create socks client this module could be used to create socks server. See examples below.

EXAMPLES

For complete examples of socks 4/5 client and server see `examples' subdirectory in the distribution.

METHODS

Socks Client

new( %cfg )

new_from_socket($socket, %cfg)

new_from_fd($socket, %cfg)

Creates a new IO::Socket::Socks client object. new_from_socket() is the same as new(), but allows one to create object from an existing and not connected socket (new_from_fd is new_from_socket alias). To make IO::Socket::Socks object from connected socket see "start_SOCKS"

Both takes the following config hash:

SocksVersion => 4 or 5. Default is 5

Timeout => connect/accept timeout

Blocking => Since IO::Socket::Socks version 0.5 you can perform non-blocking connect/bind by 
            passing false value for this option. Default is true - blocking. See ready()
            below for more details.

SocksResolve => resolve host name to ip by proxy server or 
                not (will resolve by client). This
                overrides value of $SOCKS4_RESOLVE or $SOCKS5_RESOLVE
                variable. Boolean.

SocksDebug => This will cause all of the SOCKS traffic to
              be presented on the command line in a form
              similar to the tables in the RFCs. This overrides value
              of $SOCKS_DEBUG variable. Boolean.

ProxyAddr => Hostname of the proxy

ProxyPort => Port of the proxy

ConnectAddr => Hostname of the remote machine

ConnectPort => Port of the remote machine

BindAddr => Hostname of the remote machine which will
            connect to the proxy server after bind request

BindPort => Port of the remote machine which will
            connect to the proxy server after bind request

UdpAddr => Associate UDP socket on the server with this client
           hostname

UdpPort => Associate UDP socket on the server with this client
           port

AuthType => What kind of authentication to support:
            none       - no authentication (default)
            userpass  - Username/Password. For socks5
            proxy only.

RequireAuth => Do not send ANON as a valid auth mechanism.
               For socks5 proxy only

Username => For socks5 if AuthType is set to userpass, then
            you must provide a username. For socks4 proxy with
            this option you can specify userid.

Password => If AuthType is set to userpass, then you must
            provide a password. For socks5 proxy only.

The following options should be specified:

(ProxyAddr and ProxyPort)
(ConnectAddr and ConnectPort) or (BindAddr and BindPort) or (UdpAddr and UdpPort)

Other options are facultative.

start_SOCKS($socket, %cfg)

This is a class method to start socks handshake on already connected socket. This will bless passed $socket to IO::Socket::Socks class. %cfg is like hash in the constructor. Only options listed below makes sence:

Timeout
ConnectAddr
ConnectPort
BindAddr
BindPort
UdpAddr
UdpPort
SocksVersion
SocksDebug
SocksResolve
AuthType
RequireAuth
Username
Password
AuthMethods

On success this method will return same $socket, but as IO::Socket::Socks object. On failure it will return undef (but socket will be still blessed to IO::Socket::Socks class). See example:

use IO::Socket;
use IO::Socket::Socks;

my $sock = IO::Socket::INET->new("$proxy_host:$proxy_port") or die $@;
$sock = IO::Socket::Socks->start_SOCKS($sock, ConnectAddr => "google.com", ConnectPort => 80) or die $SOCKS_ERROR;

version( )

Returns socks version for this socket

ready( )

Returns true when socket becomes ready to transfer data (socks handshake done), false otherwise. This is useful for non-blocking connect/bind. When this method returns false value you can determine what socks handshake need for with $SOCKS_ERROR variable. It may need for read, then $SOCKS_ERROR will be SOCKS_WANT_READ or need for write, then it will be SOCKS_WANT_WRITE.

Example:

use IO::Socket::Socks;
use IO::Select;

my $sock = IO::Socket::Socks->new(
    ProxyAddr => 'localhost', ProxyPort => 1080, ConnectAddr => 'mail.com', ConnectPort => 80, Blocking => 0
) or die $SOCKS_ERROR;

my $sel = IO::Select->new($sock);
until ($sock->ready) {
    if ($SOCKS_ERROR == SOCKS_WANT_READ) {
        $sel->can_read();
    }
    elsif ($SOCKS_ERROR == SOCKS_WANT_WRITE) {
        $sel->can_write();
    }
    else {
        die $SOCKS_ERROR;
    }
}

# you may want to return socket to blocking state by $sock->blocking(1)
$sock->syswrite("I am ready");

accept( )

Accept an incoming connection after bind request. On failed returns undef. On success returns socket. No new socket created, returned socket is same on which this method was called. Because accept(2) is not invoked on the client side, socks server calls accept(2) and proxify all traffic via socket opened by client bind request. You can call accept only once on IO::Socket::Socks client socket.

command( %cfg )

Allows one to execute socks command on already opened socket. Thus you can create socks chain. For example see "EXAMPLES" section.

%cfg is like hash in the constructor. Only options listed below makes sence:

ConnectAddr
ConnectPort
BindAddr
BindPort
UdpAddr
UdpPort
SocksVersion
SocksDebug
SocksResolve
AuthType
RequireAuth
Username
Password
AuthMethods

Values of the other options (Timeout for example) inherited from the constructor. Options like ProxyAddr and ProxyPort are not included.

dst( )

Return (host, port) of the remote host after connect/accept or socks server (host, port) after bind/udpassoc.

Socks Server

new( %cfg )

new_from_socket($socket, %cfg)

new_from_fd($socket, %cfg)

Creates a new IO::Socket::Socks server object. new_from_socket() is the same as new(), but allows one to create object from an existing socket (new_from_fd is new_from_socket alias). Both takes the following config hash:

SocksVersion => 4 for socks4, 5 for socks5 or [4,5] if you want accept both 4 and 5. Default is 5

Timeout => Timeout value for various operations

Blocking => Since IO::Socket::Socks version 0.6 you can perform non-blocking accept by 
            passing false value for this option. Default is true - blocking. See ready()
            below for more details.

SocksResolve => For socks v5: return destination address to the client
                in form of 4 bytes if true, otherwise in form of host
                length and host name.
                For socks v4: allow use socks4a protocol extension if
                true and not otherwise.
                This overrides value of $SOCKS4_RESOLVE or $SOCKS5_RESOLVE.

SocksDebug => This will cause all of the SOCKS traffic to
              be presented on the command line in a form
              similar to the tables in the RFCs. This overrides value
              of $SOCKS_DEBUG variable. Boolean.

ProxyAddr => Local host bind address

ProxyPort => Local host bind port

UserAuth => Reference to a function that returns 1 if client
            allowed to use socks server, 0 otherwise. For
            socks5 proxy it takes login and password as
            arguments. For socks4 argument is userid.

RequireAuth => Not allow anonymous access for socks5 proxy.

Listen => Same as IO::Socket::INET listen option. Should be
          specified as number > 0.

The following options should be specified:

Listen
ProxyAddr
ProxyPort

Other options are facultative.

accept( )

Accept an incoming connection and return a new IO::Socket::Socks object that represents that connection. You must call command() on this to find out what the incoming connection wants you to do, and then call command_reply() to send back the reply.

version( )

Returns socks version for socket. It is useful when your server accepts both 4 and 5 version. Then you should know socks version to make proper response. Just call version() on socket received after accept().

ready( )

After non-blocking accept you will get new client socket object, which may be not ready to transfer data (if socks handshake is not done yet). ready() will return true value when handshake will be done successfully and false otherwise. Note, socket returned by accept() call will be always in blocking mode. So if your program can't block you should set non-blocking mode for this socket before ready() call: $socket->blocking(0). When ready() returns false value you can determine what socks handshake needs for with $SOCKS_ERROR variable. It may need for read, then $SOCKS_ERROR will be SOCKS_WANT_READ or need for write, then it will be SOCKS_WANT_WRITE.

Example:

use IO::Socket::Socks;
use IO::Select;

my $server = IO::Socket::Socks->new(ProxyAddr => 'localhost', ProxyPort => 1080, Blocking => 0)
    or die $@;
my $select = IO::Select->new($server);
$select->can_read(); # wait for client

my $client = $server->accept()
  or die "accept(): $! ($SOCKS_ERROR)";
$client->blocking(0); # !!!
$select->add($client);
$select->remove($server); # no more connections

while (1) {
    if ($client->ready) {
        my $command = $client->command;
        
        ... # do client command
        
        $client->command_reply(IO::Socket::Socks::REPLY_SUCCESS, $command->[1], $command->[2]);
        
        ... # transfer traffic
        
        last;
    }
    elsif ($SOCKS_ERROR == SOCKS_WANT_READ) {
        $select->can_read();
    }
    elsif ($SOCKS_ERROR == SOCKS_WANT_WRITE) {
        $select->can_write();
    }
    else {
        die "Unexpected error: $SOCKS_ERROR";
    }
}

command( )

After you call accept() the client has sent the command they want you to process. This function should be called on the socket returned by accept(). It returns a reference to an array with the following format:

[ COMMAND, ADDRESS, PORT, ADDRESS TYPE ]

command_reply( REPLY CODE, ADDRESS, PORT )

After you call command() the client needs to be told what the result is. The REPLY CODE is one of the constants as follows (integer value):

For socks v4
REQUEST_GRANTED(90): request granted
REQUEST_FAILED(91): request rejected or failed
REQUEST_REJECTED_IDENTD(92): request rejected becasue SOCKS server cannot connect to identd on the client
REQUEST_REJECTED_USERID(93): request rejected because the client program and identd report different user-ids

For socks v5
REPLY_SUCCESS(0): Success
REPLY_GENERAL_FAILURE(1): General Failure
REPLY_CONN_NOT_ALLOWED(2): Connection Not Allowed
REPLY_NETWORK_UNREACHABLE(3): Network Unreachable
REPLY_HOST_UNREACHABLE(4): Host Unreachable
REPLY_CONN_REFUSED(5): Connection Refused
REPLY_TTL_EXPIRED(6): TTL Expired
REPLY_CMD_NOT_SUPPORTED(7): Command Not Supported
REPLY_ADDR_NOT_SUPPORTED(8): Address Not Supported

HOST and PORT are the resulting host and port that you use for the command.

VARIABLES

$SOCKS_ERROR

This scalar behaves like $! in that if undef is returned. $SOCKS_ERROR is IO::Socket::Socks::Error object with some overloaded operators. In string context this variable should contain a string reason for the error. In numeric context it contains error code.

$SOCKS4_RESOLVE

If this variable has true value resolving of host names will be done by proxy server, otherwise resolving will be done locally. Resolving host by socks proxy version 4 is extension to the protocol also known as socks4a. So, only socks4a proxy supports resolving of hostnames. Default value of this variable is false. This variable is not importable. See also `SocksResolve' parameter in the constructor.

$SOCKS5_RESOLVE

If this variable has true value resolving of host names will be done by proxy server, otherwise resolving will be done locally. Note: some bugous socks5 servers doesn't support resolving of host names. Default value is true. This variable is not importable. See also `SocksResolve' parameter in the constructor.

$SOCKS_DEBUG

Default value is $ENV{SOCKS_DEBUG}. If this variable has true value and no SocksDebug option in the constructor specified, then SocksDebug will has true value. This variable is not importable.

CONSTANTS

The following constants could be imported manually or using `:constants' tag:

SOCKS5_VER
SOCKS4_VER
ADDR_IPV4
ADDR_DOMAINNAME
ADDR_IPV6
CMD_CONNECT
CMD_BIND
CMD_UDPASSOC
AUTHMECH_ANON
AUTHMECH_USERPASS
AUTHMECH_INVALID
AUTHREPLY_SUCCESS
AUTHREPLY_FAILURE
ISS_UNKNOWN_ADDRESS
ISS_BAD_VERSION
REPLY_SUCCESS
REPLY_GENERAL_FAILURE
REPLY_CONN_NOT_ALLOWED
REPLY_NETWORK_UNREACHABLE
REPLY_HOST_UNREACHABLE
REPLY_CONN_REFUSED
REPLY_TTL_EXPIRED
REPLY_CMD_NOT_SUPPORTED
REPLY_ADDR_NOT_SUPPORTED
REQUEST_GRANTED
REQUEST_FAILED
REQUEST_REJECTED_IDENTD
REQUEST_REJECTED_USERID
SOCKS_WANT_READ
SOCKS_WANT_WRITE
ESOCKSPROTO

SOCKS_WANT_READ, SOCKS_WANT_WRITE and ESOCKSPROTO are imported by default.

FAQ

How to determine is connection to socks server (client accept) failed or some protocol error occurred?

You can check $! variable. If $! == ESOCKSPROTO constant, then it was error in the protocol. Error description could be found in $SOCKS_ERROR.

How to determine which error in the protocol occurred?

You should compare $SOCKS_ERROR with constants below:

AUTHMECH_INVALID
AUTHREPLY_FAILURE
ISS_UNKNOWN_ADDRESS # address type sent by client/server not supported by I::S::S
ISS_BAD_VERSION     # socks version sent by client/server != specified version
REPLY_GENERAL_FAILURE
REPLY_CONN_NOT_ALLOWED
REPLY_NETWORK_UNREACHABLE
REPLY_HOST_UNREACHABLE
REPLY_CONN_REFUSED
REPLY_TTL_EXPIRED
REPLY_CMD_NOT_SUPPORTED
REPLY_ADDR_NOT_SUPPORTED
REQUEST_FAILED
REQUEST_REJECTED_IDENTD
REQUEST_REJECTED_USERID

BUGS

The following options are not implemented:

GSSAPI authentication
UDP server side support
IPV6 support

Patches are welcome.

SEE ALSO

IO::Socket::Socks::Wrapper

AUTHOR

Original author is Ryan Eatmon

Now maintained by Oleg G <oleg@cpan.org>

COPYRIGHT

This module is free software, you can redistribute it and/or modify it under the terms of LGPL.