Python 实现DNS服务器(Pyhon域名解析服务器)

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Date	: 2014-06-29 03:01:25
# @Author  : Your Name ([email protected])
# @Link	: http://example.org
# @Version : $Id$

import SocketServer
import struct
import socket as socketlib
# DNS Query
class SinDNSQuery:
	def __init__(self, data):
		i = 1
		self.name = ''
		while True:
			d = ord(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:
	def __init__(self, data):
		(self.id, self.flags, self.quests, self.answers, self.author, self.addition) = struct.unpack('>HHHHHH', data[0:12])
		self.query = SinDNSQuery(data[12:])
	def getname(self):
		return self.query.name
	def setip(self, ip):
		self.answer = SinDNSAnswer(ip)
		self.answers = 1
		self.flags = 33152
	def getbytes(self):
		res = struct.pack('>HHHHHH', self.id, self.flags, self.quests, self.answers, self.author, self.addition)
		res = res + self.query.getbytes()
		if self.answers != 0:
			res = res + self.answer.getbytes()
		return res
# A UDPHandler to handle DNS query
class SinDNSUDPHandler(SocketServer.BaseRequestHandler):
	def handle(self):
		data = self.request[0].strip()
		dns = SinDNSFrame(data)
		socket = self.request[1]
		namemap = SinDNSServer.namemap
		if(dns.query.type==1):
			# If this is query a A record, then response it
			
			name = dns.getname();
			toip = None
			ifrom = "map"
			if namemap.__contains__(name):
				# If have record, response it
				# dns.setip(namemap[name])
				# socket.sendto(dns.getbytes(), self.client_address)
				toip = namemap[name]
			elif namemap.__contains__('*'):
				# Response default address
				# dns.setip(namemap['*'])
				# socket.sendto(dns.getbytes(), self.client_address)
				toip = namemap['*']
			else:
				# ignore it
				# socket.sendto(data, self.client_address)
				# socket.getaddrinfo(name,0)
				try:
					toip = socketlib.getaddrinfo(name,0)[0][4][0]
					ifrom = "sev"
					# namemap[name] = toip
					# print socket.getaddrinfo(name,0)
				except Exception, e:
					print 'get ip fail'
			if toip:
				dns.setip(toip)
			print '%s: %s-->%s (%s)'%(self.client_address[0], name, toip, ifrom)
			socket.sendto(dns.getbytes(), self.client_address)
		else:
			# If this is not query a A record, ignore it
			socket.sendto(data, self.client_address)

# DNS Server
# It only support A record query
# user it, U can create a simple DNS server
class SinDNSServer:
	def __init__(self, port=53):
		SinDNSServer.namemap = {}
		self.port = port
	def addname(self, name, ip):
		SinDNSServer.namemap[name] = ip
	def start(self):
		HOST, PORT = "0.0.0.0", self.port
		server = SocketServer.UDPServer((HOST, PORT), SinDNSUDPHandler)
		server.serve_forever()

# Now, test it
if __name__ == "__main__":
	sev = SinDNSServer()
	sev.addname('www.aa.com', '192.168.0.1')	# add a A record
	sev.addname('www.bb.com', '192.168.0.2')	# add a A record
	# sev.addname('*', '0.0.0.0') # default address
	sev.start() # start DNS server

# Now, U can use "nslookup" command to test it
# Such as "nslookup www.aa.com"

因为突然有个邪恶的想法，想在自己的Android平板上面搭建一个DNS服务器，因为平板上之前安装过SL4A和Python的解释器，也想继续学学Python因此，就打算用Python实现了。

在Google上面找了一下,Python实现的DNS，没找到我所希望的答案，因此就决定自己来实现了。

现在所实现的没什么高深的，只是能够对A记录查询进行简单的匹配和回复。

实现的代码如下：

py3

'''
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:
    def __init__(self, data):
        (self.id, self.flags, self.quests, self.answers, self.author, self.addition) = struct.unpack('>HHHHHH', data[0:12])
        self.query = SinDNSQuery(data[12:])
    def getname(self):
        return self.query.name
    def setip(self, ip):
        self.answer = SinDNSAnswer(ip)
        self.answers = 1
        self.flags = 33152
    def getbytes(self):
        res = struct.pack('>HHHHHH', self.id, self.flags, self.quests, self.answers, self.author, self.addition)
        res = res + self.query.getbytes()
        if self.answers != 0:
            res = res + self.answer.getbytes()
        return res
# A UDPHandler to handle DNS query
class SinDNSUDPHandler(socketserver.BaseRequestHandler):
    def handle(self):
        data = self.request[0].strip()
        dns = SinDNSFrame(data)
        socket = self.request[1]
        namemap = SinDNSServer.namemap
        if(dns.query.type==1):
            # If this is query a A record, then response it
            
            name = dns.getname();
            if namemap.__contains__(name):
                # If have record, response it
                dns.setip(namemap[name])
                socket.sendto(dns.getbytes(), self.client_address)
            elif namemap.__contains__('*'):
                # Response default address
                dns.setip(namemap['*'])
                socket.sendto(dns.getbytes(), self.client_address)
            else:
                # ignore it
                socket.sendto(data, self.client_address)
        else:
            # If this is not query a A record, ignore it
            socket.sendto(data, self.client_address)

# DNS Server
# It only support A record query
# user it, U can create a simple DNS server
class SinDNSServer:
    def __init__(self, port=53):
        SinDNSServer.namemap = {}
        self.port = port
    def addname(self, name, ip):
        SinDNSServer.namemap[name] = ip
    def start(self):
        HOST, PORT = "0.0.0.0", self.port
        server = socketserver.UDPServer((HOST, PORT), SinDNSUDPHandler)
        server.serve_forever()

# Now, test it
if __name__ == "__main__":
    sev = SinDNSServer()
    sev.addname('www.aa.com', '192.168.0.1')    # add a A record
    sev.addname('www.bb.com', '192.168.0.2')    # add a A record
    sev.addname('*', '0.0.0.0') # default address
    sev.start() # start DNS server

# Now, U can use "nslookup" command to test it
# Such as "nslookup www.aa.com"

py2