TCPSocket proxy monkey patch

tcp_socket_proxy_monkey_patch.rb

# Usage:
#
# TCPSocket.socks_server = "socks-proxy.example.net"
# TCPSocket.socks_port   = 8888

require 'socket'

class TCPSocket

  alias :direct_to :initialize

  class << self
    attr_accessor :socks_server, :socks_port
  end

  def initialize(host, port, local_host = nil, local_port = nil)
    socks_server = self.class.socks_server
    socks_port   = self.class.socks_port

    if socks_server && socks_port
      direct socks_server, socks_port
      authenticate
      proxy_to(host, port)
    else
      direct_to host, port, local_host, local_port
    end
  end

  def authenticate
    # no authentication
    write "\005\001\000"
    recv(2)
  end

  def proxy_to(host, port)
    ["\005", "\001", "\000"].map {|b| write b }

    if host =~ /^(\d+)\.(\d+)\.(\d+)\.(\d+)$/
      write "\001"
      write [$1.to_i, $2.to_i, $3.to_i, $4.to_i].pack("CCCC")
    elsif host =~ /^[:0-9a-f]+$/
      raise "TCP/IPv6 is not supported via SOCKS"
    else
      write "\003" + [host.size].pack("C") + host
    end

    write [port].pack('n')

    receive_via_proxy
  end

  def receive_via_proxy
    reply = recv(4)

    raise "SOCKS version #{reply[0..0]} is not supported" if reply[0..0] != "\005"
    raise "SOCKS error: #{reply.bytes.to_a.inspect}" if reply[1..1] != "\000"

    bind_addr_len = case reply[3..3]
      when "\001"
        4
      when "\003"
        recv(1).bytes.first
      when "\004"
        16
      else
        raise "SOCKS error: #{reply.bytes.to_a.inspect}"
      end

    bind_addr_s = recv(bind_addr_len)

    bind_addr = case reply[3..3]
      when "\001"
        bind_addr_s.bytes.to_a.join(".")
      when "\003"
        bind_addr_s
      end

    [bind_addr, recv(bind_addr_len + 2).unpack("n")]
  end
end