我正在尝试编写基于Twisted的模拟DNS服务器来进行一些测试。
[从this guide获得灵感,我编写了一个非常简单的服务器,它将所有内容解析为127.0.0.1
:
from twisted.internet import defer, reactor
from twisted.names import dns, error, server
class MockDNSResolver:
def _doDynamicResponse(self, query):
name = query.name.name
record = dns.Record_A(address=b"127.0.0.1")
answer = dns.RRHeader(name=name, payload=record)
authority = []
additional = []
return [answer], authority, additional
def query(self, query, timeout=None):
print("Incoming query for:", query.name)
if query.type == dns.A:
return defer.succeed(self._doDynamicResponse(query))
else:
return defer.fail(error.DomainError())
if __name__ == "__main__":
clients = [MockDNSResolver()]
factory = server.DNSServerFactory(clients=clients)
protocol = dns.DNSDatagramProtocol(controller=factory)
reactor.listenUDP(10053, protocol)
reactor.listenTCP(10053, factory)
reactor.run()
以上在dig
和nslookup
(从另一个终端)上正常工作:
$ dig -p 10053 @localhost something.example.org A +short
127.0.0.1
$ nslookup something.else.example.org 127.0.0.1 -port=10053
Server: 127.0.0.1
Address: 127.0.0.1#10053
Non-authoritative answer:
Name: something.else.example.org
Address: 127.0.0.1
我还在运行服务器的终端上获得了相应的匹配:
Incoming query for: something.example.org
Incoming query for: something.else.example.org
然后,我根据this section about making requests和this section about installing a custom resolver编写了以下代码:
from twisted.internet import reactor
from twisted.names.client import createResolver
from twisted.web.client import Agent
d = Agent(reactor).request(b'GET', b'http://does.not.exist')
reactor.installResolver(createResolver(servers=[('127.0.0.1', 10053)]))
def callback(result):
print('Result:', result)
d.addBoth(callback)
d.addBoth(lambda _: reactor.stop())
reactor.run()
但是这失败(并且服务器终端中没有任何行)。好像查询不是去模拟服务器,而是去系统定义的服务器:
Result: [Failure instance: Traceback: <class 'twisted.internet.error.DNSLookupError'>: DNS lookup failed: no results for hostname lookup: does.not.exist.
/.../venv/lib/python3.6/site-packages/twisted/internet/_resolver.py:137:deliverResults
/.../venv/lib/python3.6/site-packages/twisted/internet/endpoints.py:921:resolutionComplete
/.../venv/lib/python3.6/site-packages/twisted/internet/defer.py:460:callback
/.../venv/lib/python3.6/site-packages/twisted/internet/defer.py:568:_startRunCallbacks
--- <exception caught here> ---
/.../venv/lib/python3.6/site-packages/twisted/internet/defer.py:654:_runCallbacks
/.../venv/lib/python3.6/site-packages/twisted/internet/endpoints.py:975:startConnectionAttempts
]
我正在使用:
感谢您的帮助,如果需要其他信息,请告诉我。
谢谢!
这正在工作,我将更新答案以使其更简单。
from twisted.internet import reactor
from twisted.names import client
resolver = client.createResolver(servers=[('127.0.0.1', 10053)])
d = resolver.getHostByName('does.not.exist')
def callback(result):
print('Result:', result)
d.addBoth(callback)
reactor.callLater(4, reactor.stop)
reactor.run()
我也更改了模拟DNS解析器:
from twisted.internet import defer, reactor
from twisted.names import dns, error, server, common
class MockDNSResolver(common.ResolverBase):
def _lookup(self, name, cls, type, timeout):
print("Incoming query for:", name)
record = dns.Record_A(address=b"127.0.0.5")
answer = dns.RRHeader(name=name, payload=record)
return defer.succeed(([answer], [], []))
if __name__ == "__main__":
clients = [MockDNSResolver()]
factory = server.DNSServerFactory(clients=clients)
protocol = dns.DNSDatagramProtocol(controller=factory)
reactor.listenUDP(10053, protocol)
reactor.listenTCP(10053, factory)
reactor.run()