#!/usr/bin/env python3 # This is just a toy, real code would check that the received message # really was a NOTIFY, and otherwise handle errors. import socket import dns.flags import dns.message import dns.rdataclass import dns.rdatatype import dns.name from typing import cast address = "127.0.0.1" port = 53535 s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) s.bind((address, port)) while True: (wire, address) = s.recvfrom(512) notify = dns.message.from_wire(wire) try: soa = notify.find_rrset( notify.answer, notify.question[0].name, dns.rdataclass.IN, dns.rdatatype.SOA ) # Do something with the SOA RR here print("The serial number for", soa.name, "is", soa[0].serial) except KeyError: # No SOA RR in the answer section. pass response = dns.message.make_response(notify) # type: dns.message.Message response.flags |= dns.flags.AA wire = response.to_wire(cast(dns.name.Name, response)) s.sendto(wire, address)