1#!/usr/bin/env python3 2# Copyright 2015 gRPC authors. 3# 4# Licensed under the Apache License, Version 2.0 (the "License"); 5# you may not use this file except in compliance with the License. 6# You may obtain a copy of the License at 7# 8# http://www.apache.org/licenses/LICENSE-2.0 9# 10# Unless required by applicable law or agreed to in writing, software 11# distributed under the License is distributed on an "AS IS" BASIS, 12# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13# See the License for the specific language governing permissions and 14# limitations under the License. 15"""Makes DNS queries for A records to specified servers""" 16 17import argparse 18import threading 19import time 20 21import twisted.internet.reactor as reactor 22import twisted.internet.task as task 23import twisted.names.client as client 24 25 26def main(): 27 argp = argparse.ArgumentParser(description="Make DNS queries for A records") 28 argp.add_argument( 29 "-s", 30 "--server_host", 31 default="127.0.0.1", 32 type=str, 33 help="Host for DNS server to listen on for TCP and UDP.", 34 ) 35 argp.add_argument( 36 "-p", 37 "--server_port", 38 default=53, 39 type=int, 40 help="Port that the DNS server is listening on.", 41 ) 42 argp.add_argument( 43 "-n", 44 "--qname", 45 default=None, 46 type=str, 47 help="Name of the record to query for. ", 48 ) 49 argp.add_argument( 50 "-t", 51 "--timeout", 52 default=1, 53 type=int, 54 help="Force process exit after this number of seconds.", 55 ) 56 args = argp.parse_args() 57 58 def OnResolverResultAvailable(result): 59 answers, authority, additional = result 60 for a in answers: 61 print(a.payload) 62 63 def BeginQuery(reactor, qname): 64 servers = [(args.server_host, args.server_port)] 65 resolver = client.Resolver(servers=servers) 66 deferred_result = resolver.lookupAddress(args.qname) 67 deferred_result.addCallback(OnResolverResultAvailable) 68 return deferred_result 69 70 task.react(BeginQuery, [args.qname]) 71 72 73if __name__ == "__main__": 74 main() 75