1#!/usr/bin/env python2.7 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 16"""Makes DNS queries for A records to specified servers""" 17 18import argparse 19import threading 20import time 21import twisted.internet.task as task 22import twisted.names.client as client 23import twisted.internet.reactor as reactor 24 25 26def main(): 27 argp = argparse.ArgumentParser(description='Make DNS queries for A records') 28 argp.add_argument('-s', '--server_host', default='127.0.0.1', type=str, 29 help='Host for DNS server to listen on for TCP and UDP.') 30 argp.add_argument('-p', '--server_port', default=53, type=int, 31 help='Port that the DNS server is listening on.') 32 argp.add_argument('-n', '--qname', default=None, type=str, 33 help=('Name of the record to query for. ')) 34 argp.add_argument('-t', '--timeout', default=1, type=int, 35 help=('Force process exit after this number of seconds.')) 36 args = argp.parse_args() 37 def OnResolverResultAvailable(result): 38 answers, authority, additional = result 39 for a in answers: 40 print(a.payload) 41 def BeginQuery(reactor, qname): 42 servers = [(args.server_host, args.server_port)] 43 resolver = client.Resolver(servers=servers) 44 deferred_result = resolver.lookupAddress(args.qname) 45 deferred_result.addCallback(OnResolverResultAvailable) 46 return deferred_result 47 task.react(BeginQuery, [args.qname]) 48 49if __name__ == '__main__': 50 main() 51