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# -*- coding: utf-8 -*-
"""
FixedResolver - example resolver which responds with fixed response
to all requests
"""
from __future__ import print_function
import copy
from dnslib import RR
from dnslib.server import DNSServer,DNSHandler,BaseResolver,DNSLogger
class FixedResolver(BaseResolver):
"""
Respond with fixed response to all requests
"""
def __init__(self,zone):
# Parse RRs
self.rrs = RR.fromZone(zone)
def resolve(self,request,handler):
reply = request.reply()
qname = request.q.qname
# Replace labels with request label
for rr in self.rrs:
a = copy.copy(rr)
a.rname = qname
reply.add_answer(a)
return reply
if __name__ == '__main__':
import argparse,sys,time
p = argparse.ArgumentParser(description="Fixed DNS Resolver")
p.add_argument("--response","-r",default=". 60 IN A 127.0.0.1",
metavar="<response>",
help="DNS response (zone format) (default: 127.0.0.1)")
p.add_argument("--zonefile","-f",
metavar="<zonefile>",
help="DNS response (zone file, '-' for stdin)")
p.add_argument("--port","-p",type=int,default=53,
metavar="<port>",
help="Server port (default:53)")
p.add_argument("--address","-a",default="",
metavar="<address>",
help="Listen address (default:all)")
p.add_argument("--udplen","-u",type=int,default=0,
metavar="<udplen>",
help="Max UDP packet length (default:0)")
p.add_argument("--tcp",action='store_true',default=False,
help="TCP server (default: UDP only)")
p.add_argument("--log",default="request,reply,truncated,error",
help="Log hooks to enable (default: +request,+reply,+truncated,+error,-recv,-send,-data)")
p.add_argument("--log-prefix",action='store_true',default=False,
help="Log prefix (timestamp/handler/resolver) (default: False)")
args = p.parse_args()
if args.zonefile:
if args.zonefile == '-':
args.response = sys.stdin
else:
args.response = open(args.zonefile)
resolver = FixedResolver(args.response)
logger = DNSLogger(args.log,args.log_prefix)
print("Starting Fixed Resolver (%s:%d) [%s]" % (
args.address or "*",
args.port,
"UDP/TCP" if args.tcp else "UDP"))
for rr in resolver.rrs:
print(" | ",rr.toZone().strip(),sep="")
print()
if args.udplen:
DNSHandler.udplen = args.udplen
udp_server = DNSServer(resolver,
port=args.port,
address=args.address,
logger=logger)
udp_server.start_thread()
if args.tcp:
tcp_server = DNSServer(resolver,
port=args.port,
address=args.address,
tcp=True,
logger=logger)
tcp_server.start_thread()
while udp_server.isAlive():
time.sleep(1)
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