使用自定义后端的Python DNS服务器

Question

有没有用Python写的DNS服务器，我可以很方便地使用自己的后台？

其实，我就是想为一些域名提供我自己的IP地址的查询结果，但其他的查询就交给真正的DNS服务器处理。

Answer 1

很多人会建议你用Twisted来写这个，并且加一些自定义的功能，这样你就可以自己回答请求了。如果你想了解更多，可以看看这些链接：

http://twistedmatrix.com/documents/10.1.0/names/howto/names.html

http://twistedmatrix.com/documents/10.1.0/api/twisted.names.dns.DNSDatagramProtocol.html

Answer 2

其实，我发现了一种更简单的方法：使用PowerDNS和管道后端。

http://doc.powerdns.com/pipebackend-dynamic-resolution.html

http://doc.powerdns.com/backends-detail.html#PIPEBACKEND

只需安装PowerDNS服务器，写一个小脚本把请求转发到你的服务器，这样就完成了。

Answer 3

我最近写了一个这样的东西，也许你可以把它当作一个例子。它使用了一个DHT作为后端，并在那里面查找所有的.kad域名。如果你简单地把P2PMapping替换成你自己的映射（比如一个字典，像{'google.com' : '127.0.0.1'}），它应该就能实现你想要的功能。

"""
Created on 16.08.2010

@author: Jochen Ritzel
"""

import dht

from twisted.names import dns, server, client, cache
from twisted.application import service, internet

class P2PMapping(dht.EntangledDHT):

    def __contains__(self, key):
        return key.endswith('.kad')

class MapResolver(client.Resolver):
    """
    Resolves names by looking in a mapping. 
    If `name in mapping` then mapping[name] should return a IP
    else the next server in servers will be asked for name    
    """
    def __init__(self, mapping, servers):
        self.mapping = mapping
        client.Resolver.__init__(self, servers=servers)
        self.ttl = 10

    def lookupAddress(self, name, timeout = None):
        # find out if this is a .kad. request
        if name in self.mapping:
            result = self.mapping[name] # get the result
            def packResult( value ):
                return [
                        (dns.RRHeader(name, dns.A, dns.IN, self.ttl, dns.Record_A(value, self.ttl)),), (), ()
                ]
            result.addCallback(packResult) # put it in a A Record
            return result
        else:
            return self._lookup(name, dns.IN, dns.A, timeout)


## this sets up the application


application = service.Application('dnsserver', 1, 1)


## set up the DHT
mapping = P2PMapping(bootstrap=[('127.0.0.1', 4001)])
mapping['jochen.kad'] = '99.99.99.99' # "register" domain with IP


# set up a resolver that uses the mapping or a secondary nameserver
p2presolver = MapResolver(mapping, servers=[('192.168.178.1', 53)])


# create the protocols
f = server.DNSServerFactory(caches=[cache.CacheResolver()], clients=[p2presolver])
p = dns.DNSDatagramProtocol(f)
f.noisy = p.noisy = False


# register as tcp and udp
ret = service.MultiService()
PORT=53

for (klass, arg) in [(internet.TCPServer, f), (internet.UDPServer, p)]:
    s = klass(PORT, arg)
    s.setServiceParent(ret)


# run all of the above as a twistd application
ret.setServiceParent(service.IServiceCollection(application))


# run it through twistd!
if __name__ == '__main__':
    import sys
    print "Usage: twistd -y %s" % sys.argv[0]