class Gem::Resolv::DNS::Requester::TCP

def close
  super
  @senders.each_key {|from,id|
    DNS.free_request_id(@host, @port, id)
  }
end

def initialize(host, port=Port)
  super()
  @host = host
  @port = port
  sock = TCPSocket.new(@host, @port)
  @socks = [sock]
  @senders = {}
end

def recv_reply(readable_socks)
  len = readable_socks[0].read(2).unpack('n')[0]
  reply = @socks[0].read(len)
  return reply, nil
end

def sender(msg, data, host=@host, port=@port)
  unless host == @host && port == @port
    raise RequestError.new("host/port don't match: #{host}:#{port}")
  end
  id = DNS.allocate_request_id(@host, @port)
  request = msg.encode
  request[0,2] = [request.length, id].pack('nn')
  return @senders[[nil,id]] = Sender.new(request, data, @socks[0])
end