new_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  
  # Copyright (c) 2014 clowwindy
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
  # in the Software without restriction, including without limitation the rights
  # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  # copies of the Software, and to permit persons to whom the Software is
  # furnished to do so, subject to the following conditions:
  #
  # The above copyright notice and this permission notice shall be included in
  # all copies or substantial portions of the Software.
  #
  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  # SOFTWARE.
  
  import socket
  import struct
  import common
  
  
  _request_count = 1
  
  # rfc1035
  #                                 1  1  1  1  1  1
  #   0  1  2  3  4  5  6  7  8  9  0  1  2  3  4  5
  # +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
  # |                      ID                       |
  # +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
  # |QR|   Opcode  |AA|TC|RD|RA|   Z    |   RCODE   |
  # +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
  # |                    QDCOUNT                    |
  # +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
  # |                    ANCOUNT                    |
  # +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
  # |                    NSCOUNT                    |
  # +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
  # |                    ARCOUNT                    |
  # +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
  
  
  def pack_request(address):
      global _request_count
      _request_count += 1
      header = struct.pack('!HBBHHHH', _request_count, 1, 0, 1, 0, 0, 0)
      pass
  
  
  def unpack_response(data):
      # TODO detect address type
      pass
  
  
  def resolve(address, callback):
      callback(address)
  
  
  def test():
      def _callback(address):
          print address
  
      resolve('www.baidu.com', _callback)
  
  
  if __name__ == '__main__':
      test()
  
subject: add asyncdns