Python Twisted 自定义 DNS

Question

我是 python 的 Twisted 框架的新手。我正在玩客户 DNS 服务器，我想知道如何定位 DNS 请求的 SRC_IP。

我正在使用以下脚本：http://twisted.readthedocs.org/en/latest/names/howto/custom-server.html

特别是动态解析并想知道我如何定位请求的源 IP 的那个。 谢谢

Answer 1

对twisted不太熟悉，我不知道这是否是最好的方式。我怀疑我在下面提出的不是因为直接在套接字上操作感觉不对，而是这样。

子类server.DNSServerFactory并覆盖handleQuery()方法，例如：

import socket
from twisted.internet.address import IPv4Address

class MyDNSServerFactory(server.DNSServerFactory):

    def handleQuery(self, message, protocol, address):
        if protocol.transport.socket.type == socket.SOCK_STREAM:
            self.peer_address = protocol.transport.getPeer()
        elif protocol.transport.socket.type == socket.SOCK_DGRAM:
            self.peer_address = IPv4Address('UDP', *address)
        else:
            print "Unexpected socket type %r" % protocol.transport.socket.type

        print "Got message from : %r" % self.peer_address
        return server.DNSServerFactory.handleQuery(self, message, protocol, address)
.
.
.

factory = MyDNSServerFactory(
    clients=[DynamicResolver(), client.Resolver(resolv='/etc/resolv.conf')]
)

需要担心的事情：

1. IPV6 地址
2. 直接使用socket 似乎很卑鄙。
3. socket.SOCK_STREAM 是否总是暗示 TCP 连接？

还有其他方法可以做到这一点，例如子类dns.DNSDatagramProtocol 并覆盖datagramReceived(self, data, addr) 以获取客户端UDP 地址。 TCP 客户端地址将通过子类化和覆盖server.DNSServerFactory.connectionMade(self, protocol) 并使用protocol.transport.getPeer() 获取对等方的地址来获得。

---

更新答案以在 DynamicResolver 中提供对等地址

修改MyDNSServerFactory.handleQuery() 为具有peer_address 属性的解析器设置peer_address：

class MyDNSServerFactory(server.DNSServerFactory):

    def handleQuery(self, message, protocol, address):
        if protocol.transport.socket.type == socket.SOCK_STREAM:
            self.peer_address = protocol.transport.getPeer()
        elif protocol.transport.socket.type == socket.SOCK_DGRAM:
            self.peer_address = IPv4Address('UDP', *address)
        else:
            print "Unexpected socket type %r" % protocol.transport.socket.type

        print "Got message from : %r" % self.peer_address

        # Make peer_address available to resolvers that support that attribute
        for resolver in self.resolver.resolvers:
            if hasattr(resolver, 'peer_address'):
                resolver.peer_address = self.peer_address

        return server.DNSServerFactory.handleQuery(self, message, protocol, address)

将以下peer_address 属性添加到类DynamicResolver：

    def __init__(self):
        self._peer_address = None

    @property
    def peer_address(self):
        return self._peer_address

    @peer_address.setter
    def peer_address(self, value):
        self._peer_address = value

现在您可以在DynamicResolver.query() 中访问peer_address，例如

    def query(self, query, timeout=None):
        print "In DynamicResolver.query(): self.peer_address = %r" % self.peer_address
        if self._dynamicResponseRequired(query):
            return defer.succeed(self._doDynamicResponse(query))
        else:
            return defer.fail(error.DomainError())