Class: Rex::Proto::Proxy::Socks5::ServerClient

Inherits:
Object
  • Object
show all
Defined in:
lib/rex/proto/proxy/socks5/server_client.rb

Overview

A client connected to the SOCKS5 server.

Constant Summary collapse

AUTH_NONE = 
0
AUTH_GSSAPI = 
1
AUTH_CREDS = 
2
AUTH_NO_ACCEPTABLE_METHODS = 
255
AUTH_PROTOCOL_VERSION = 
1
AUTH_RESULT_SUCCESS = 
0
AUTH_RESULT_FAILURE = 
1
COMMAND_CONNECT = 
1
COMMAND_BIND = 
2
COMMAND_UDP_ASSOCIATE = 
3
REPLY_SUCCEEDED = 
0
REPLY_GENERAL_FAILURE = 
1
REPLY_NOT_ALLOWED = 
2
REPLY_NET_UNREACHABLE = 
3
REPLY_HOST_UNREACHABLE = 
4
REPLY_CONNECTION_REFUSED = 
5
REPLY_TTL_EXPIRED = 
6
REPLY_CMD_NOT_SUPPORTED = 
7
REPLY_ADDRESS_TYPE_NOT_SUPPORTED = 
8
HOST = 
1
PORT = 
2

Instance Method Summary collapse

Constructor Details

#initialize(server, sock, opts = {}) ⇒ ServerClient

Create a new client connected to the server.



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# File 'lib/rex/proto/proxy/socks5/server_client.rb', line 49

def initialize(server, sock, opts={})
  @server        = server
  @lsock         = sock
  @opts          = opts
  @rsock         = nil
  @client_thread = nil
  @mutex         = ::Mutex.new
end

Instance Method Details

#handle_authentication ⇒ Object 



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# File 'lib/rex/proto/proxy/socks5/server_client.rb', line 82

def handle_authentication
  request = AuthRequestPacket.read(@lsock.get_once)
  if @opts['ServerUsername'].nil? && @opts['ServerPassword'].nil?
    handle_authentication_none(request)
  else
    handle_authentication_creds(request)
  end
end

#handle_authentication_creds(request) ⇒ Object 



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# File 'lib/rex/proto/proxy/socks5/server_client.rb', line 91

def handle_authentication_creds(request)
  unless request.supported_methods.include? AUTH_CREDS
    raise "Invalid SOCKS5 request packet received (no supported authentication methods)."
  end
  response = AuthResponsePacket.new
  response.chosen_method = AUTH_CREDS
  @lsock.put(response.to_binary_s)

  version = @lsock.read(1)
  raise "Invalid SOCKS5 authentication packet received." unless version.unpack('C').first == 0x01

  username_length = @lsock.read(1).unpack('C').first
  username        = @lsock.read(username_length)

  password_length = @lsock.read(1).unpack('C').first
  password        = @lsock.read(password_length)

  #  +-----+--------+
  #  | VER | STATUS |
  #  +-----+--------+  VERSION: 0x01
  #  | 1   | 1      |  STATUS:  0x00=SUCCESS, otherwise FAILURE
  #  +-----+--------+
  if username == @opts['ServerUsername'] && password == @opts['ServerPassword']
    raw = [ AUTH_PROTOCOL_VERSION, AUTH_RESULT_SUCCESS ].pack ('CC')
    ilog("SOCKS5: Successfully authenticated")
    @lsock.put(raw)
  else
    raw = [ AUTH_PROTOCOL_VERSION, AUTH_RESULT_FAILURE ].pack ('CC')
    @lsock.put(raw)
    raise "Invalid SOCKS5 credentials provided"
  end
end

#handle_authentication_none(request) ⇒ Object 



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# File 'lib/rex/proto/proxy/socks5/server_client.rb', line 124

def handle_authentication_none(request)
  unless request.supported_methods.include? AUTH_NONE
    raise "Invalid SOCKS5 request packet received (no supported authentication methods)."
  end
  response = AuthResponsePacket.new
  response.chosen_method = AUTH_NONE
  @lsock.put(response.to_binary_s)
end

#handle_command ⇒ Object 



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# File 'lib/rex/proto/proxy/socks5/server_client.rb', line 133

def handle_command
  request = RequestPacket.read(@lsock.get_once)
  response = nil
  case request.command
    when COMMAND_BIND
      response = handle_command_bind(request)
    when COMMAND_CONNECT
      response = handle_command_connect(request)
    when COMMAND_UDP_ASSOCIATE
      response = handle_command_udp_associate(request)
  end
  @lsock.put(response.to_binary_s) unless response.nil?
end

#handle_command_bind(request) ⇒ Object 



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# File 'lib/rex/proto/proxy/socks5/server_client.rb', line 147

def handle_command_bind(request)
  # create a server socket for this request
  params = {
    'LocalHost' => request.address_type == Address::ADDRESS_TYPE_IPV6 ? '::' : '0.0.0.0',
    'LocalPort' => 0,
  }
  params['Context'] = @server.opts['Context'] if @server.opts.has_key?('Context')
  bsock = Rex::Socket::TcpServer.create(params)

  # send back the bind success to the client
  response              = ResponsePacket.new
  response.command      = REPLY_SUCCEEDED
  response.address      = bsock.getlocalname[HOST]
  response.port         = bsock.getlocalname[PORT]
  @lsock.put(response.to_binary_s)

  # accept a client connection (2 minute timeout as per the socks4a spec)
  begin
    ::Timeout.timeout(120) do
      @rsock = bsock.accept
    end
  rescue ::Timeout::Error
    raise "Timeout reached on accept request."
  end

  # close the listening socket
  bsock.close

  setup_tcp_relay
  response              = ResponsePacket.new
  response.command      = REPLY_SUCCEEDED
  response.address      = @rsock.peerhost
  response.port         = @rsock.peerport
  response
end

#handle_command_connect(request) ⇒ Object 



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# File 'lib/rex/proto/proxy/socks5/server_client.rb', line 183

def handle_command_connect(request)
  # perform the connection request
  params = {
    'PeerHost' => request.address,
    'PeerPort' => request.port,
  }
  params['Context'] = @server.opts['Context'] if @server.opts.has_key?('Context')
  @rsock = Rex::Socket::Tcp.create(params)

  setup_tcp_relay
  response              = ResponsePacket.new
  response.command      = REPLY_SUCCEEDED
  response.address      = @rsock.getlocalname[HOST].split('-')[-1]
  response.port         = @rsock.getlocalname[PORT]
  response
end

#handle_command_udp_associate(request) ⇒ Object 



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# File 'lib/rex/proto/proxy/socks5/server_client.rb', line 200

def handle_command_udp_associate(request)
  response              = ResponsePacket.new
  response.command      = REPLY_CMD_NOT_SUPPORTED
  response
end

#setup_tcp_relay ⇒ Object

Setup the relay between lsock and rsock.



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# File 'lib/rex/proto/proxy/socks5/server_client.rb', line 209

def setup_tcp_relay
  @server.relay_manager.add_relay(@rsock, sink: @lsock, name: 'SOCKS5ProxyRelay-Remote', on_exit: method(:stop))
  @server.relay_manager.add_relay(@lsock, sink: @rsock, name: 'SOCKS5ProxyRelay-Local', on_exit: method(:stop))
end

#start ⇒ Object

Start handling the client connection.



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# File 'lib/rex/proto/proxy/socks5/server_client.rb', line 60

def start
  # create a thread to handle this client request so as to not block the socks5 server
  @client_thread = Rex::ThreadFactory.spawn("SOCKS5ProxyClient", false) do
    begin
      @server.add_client(self)
      # get the initial client request packet
      handle_authentication

      # handle the request
      handle_command
    rescue StandardError => e
      # respond with a general failure to the client
      response         = ResponsePacket.new
      response.command = REPLY_GENERAL_FAILURE
      @lsock.put(response.to_binary_s)

      elog('ServerClient#start - encountered a problem while processing the client connection', error:e)
      self.stop
    end
  end
end

#stop ⇒ Object

Stop handling the client connection.



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# File 'lib/rex/proto/proxy/socks5/server_client.rb', line 217

def stop
  @mutex.synchronize do
    unless @closed
      begin
        @lsock.close if @lsock
      rescue
      end

      begin
        @rsock.close if @rsock
      rescue
      end

      @server.remove_client(self)
      @closed = true

      unless @client_thread == Thread.current
        @client_thread.join
      end
      @client_thread = nil
    end
  end
end