因為突然有個邪惡的想法，想在自己的Android平板上面搭建一個DNS服務器，因為平板上之前安裝過SL4A和Python的解釋器，也想繼續學學Python因此，就打算用Python實現了。

在Google上面找了一下,Python實現的DNS，沒找到我所希望的答案，因此就決定自己來實現了。

現在所實現的沒什么高深的，只是能夠對A記錄查詢進行簡單的匹配和回復。

實現的代碼如下：
''
Created on 2012-10-15

@author: RobinTang
'''

import socketserver
import struct

# DNS Query
class SinDNSQuery:
    def __init__(self, data):
        i = 1
        self.name = ''
        while True:
            d = data[i]
            if d == 0:
                break;
            if d < 32:
                self.name = self.name + '.'
            else:
                self.name = self.name + chr(d)
            i = i + 1
        self.querybytes = data[0:i + 1]
        (self.type, self.classify) = struct.unpack('>HH', data[i + 1:i + 5])
        self.len = i + 5
    def getbytes(self):
        return self.querybytes + struct.pack('>HH', self.type, self.classify)

# DNS Answer RRS
# this class is also can be use as Authority RRS or Additional RRS
class SinDNSAnswer:
    def __init__(self, ip):
        self.name = 49164
        self.type = 1
        self.classify = 1
        self.timetolive = 190
        self.datalength = 4
        self.ip = ip
    def getbytes(self):
        res = struct.pack('>HHHLH', self.name, self.type, self.classify, self.timetolive, self.datalength)
        s = self.ip.split('.')
        res = res + struct.pack('BBBB', int(s[0]), int(s[1]), int(s[2]), int(s[3]))
        return res

# DNS frame
# must initialized by a DNS query frame
class SinDNSFrame: