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@messa
Created Apr 22, 2021
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#!/usr/bin/env python3
from argparse import ArgumentParser
from asyncio import run, get_running_loop, sleep, create_task
from logging import getLogger
from pathlib import Path
from dnslib import DNSRecord, DNSHeader, DNSQuestion, RR, A
logger = getLogger(Path(__file__).with_suffix('').name)
log_format = '%(asctime)s %(name)-25s %(levelname)5s: %(message)s'
def main():
p = ArgumentParser()
p.add_argument('--bind-host', default='127.0.0.1')
p.add_argument('--bind-port', '-p', type=int, default=53)
args = p.parse_args()
setup_logging()
run(async_main(args))
async def async_main(args):
loop = get_running_loop()
# https://docs.python.org/3/library/asyncio-protocol.html#udp-echo-server
transport, protocol = await loop.create_datagram_endpoint(
NameServerProtocol, local_addr=(args.bind_host, args.bind_port))
try:
while True:
await sleep(3600)
finally:
transport.close()
class NameServerProtocol:
def connection_made(self, transport):
self.transport = transport
logger.debug('connection made (transport=%r)', self.transport)
def datagram_received(self, data, addr):
logger.debug('datagram received from %r: %r (transport=%r)', addr, data, self.transport)
task = create_task(process_udp_packet(data))
def task_cb(future):
reply_data = future.result()
if reply_data:
logger.debug('Sending data to %r: %r', addr, reply_data)
self.transport.sendto(reply_data, addr)
task.add_done_callback(task_cb)
async def process_udp_packet(data):
record = DNSRecord.parse(data)
logger.debug('parsed record: %r', record)
await sleep(3)
response = record.reply()
response.add_answer(RR("abc.com",rdata=A("1.2.3.4")))
logger.debug('response: %r', response)
return response.pack()
def setup_logging():
from logging import basicConfig, DEBUG
basicConfig(format=log_format, level=DEBUG)
if __name__ == '__main__':
main()
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