Использование схем и dnslib Вот полный рекурсивный DNS-сервер, написанный на Python всего в 143 строках кода:
#!/usr/bin/env python
from __future__ import print_function
from uuid import uuid4 as uuid
from dnslib import CLASS, QR, QTYPE
from dnslib import DNSHeader, DNSQuestion, DNSRecord
from circuits.net.events import write
from circuits import Component, Debugger, Event
from circuits.net.sockets import UDPClient, UDPServer
class lookup(Event):
"""lookup Event"""
class query(Event):
"""query Event"""
class response(Event):
"""response Event"""
class DNS(Component):
def read(self, peer, data):
record = DNSRecord.parse(data)
if record.header.qr == QR["QUERY"]:
return self.fire(query(peer, record))
return self.fire(response(peer, record))
class ReturnResponse(Component):
def response(self, peer, response):
return response
class Client(Component):
channel = "client"
def init(self, server, port, channel=channel):
self.server = server
self.port = int(port)
self.transport = UDPClient(0, channel=self.channel).register(self)
self.protocol = DNS(channel=self.channel).register(self)
self.handler = ReturnResponse(channel=self.channel).register(self)
class Resolver(Component):
def init(self, server, port):
self.server = server
self.port = port
def lookup(self, qname, qclass="IN", qtype="A"):
channel = uuid()
client = Client(
self.server,
self.port,
channel=channel
).register(self)
yield self.wait("ready", channel)
self.fire(
write(
(self.server, self.port),
DNSRecord(
q=DNSQuestion(
qname,
qclass=CLASS[qclass],
qtype=QTYPE[qtype]
)
).pack()
)
)
yield (yield self.wait("response", channel))
client.unregister()
yield self.wait("unregistered", channel)
del client
class ProcessQuery(Component):
def query(self, peer, query):
qname = query.q.qname
qtype = QTYPE[query.q.qtype]
qclass = CLASS[query.q.qclass]
response = yield self.call(lookup(qname, qclass=qclass, qtype=qtype))
record = DNSRecord(
DNSHeader(id=query.header.id, qr=1, aa=1, ra=1),
q=query.q,
)
for rr in response.value.rr:
record.add_answer(rr)
yield record.pack()
class Server(Component):
def init(self, bind=("0.0.0.0", 53)):
self.bind = bind
self.transport = UDPServer(self.bind).register(self)
self.protocol = DNS().register(self)
self.handler = ProcessQuery().register(self)
class App(Component):
def init(self, bind=("0.0.0.0", 53), server="8.8.8.8", port=53,
verbose=False):
if verbose:
Debugger().register(self)
self.resolver = Resolver(server, port).register(self)
self.server = Server(bind).register(self)
def main():
App().run()
if __name__ == "__main__":
main()
Использование:
По умолчанию в этом примере привязки идут 0.0.0.0:53, поэтому вам нужно будет выполнить что-то вроде:
sudo ./dnsserver.py
В противном случае измените параметр bind.