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# -*- coding: utf-8 -*-
from __future__ import print_function
import copy
from dnslib import RR,QTYPE,RCODE
from dnslib.server import DNSServer,DNSHandler,BaseResolver,DNSLogger
class ZoneResolver(BaseResolver):
"""
Simple fixed zone file resolver.
"""
def __init__(self,zone,glob=False):
"""
Initialise resolver from zone file.
Stores RRs as a list of (label,type,rr) tuples
If 'glob' is True use glob match against zone file
"""
self.zone = [(rr.rname,QTYPE[rr.rtype],rr) for rr in RR.fromZone(zone)]
self.glob = glob
self.eq = 'matchGlob' if glob else '__eq__'
def resolve(self,request,handler):
"""
Respond to DNS request - parameters are request packet & handler.
Method is expected to return DNS response
"""
reply = request.reply()
qname = request.q.qname
qtype = QTYPE[request.q.qtype]
for name,rtype,rr in self.zone:
# Check if label & type match
if getattr(qname,self.eq)(name) and (qtype == rtype or
qtype == 'ANY' or
rtype == 'CNAME'):
# If we have a glob match fix reply label
if self.glob:
a = copy.copy(rr)
a.rname = qname
reply.add_answer(a)
else:
reply.add_answer(rr)
# Check for A/AAAA records associated with reply and
# add in additional section
if rtype in ['CNAME','NS','MX','PTR']:
for a_name,a_rtype,a_rr in self.zone:
if a_name == rr.rdata.label and a_rtype in ['A','AAAA']:
reply.add_ar(a_rr)
if not reply.rr:
reply.header.rcode = RCODE.NXDOMAIN
return reply
if __name__ == '__main__':
import argparse,sys,time
p = argparse.ArgumentParser(description="Zone DNS Resolver")
p.add_argument("--zone","-z",required=True,
metavar="<zone-file>",
help="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("--glob",action='store_true',default=False,
help="Glob match against zone file (default: false)")
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.zone == '-':
args.zone = sys.stdin
else:
args.zone = open(args.zone)
resolver = ZoneResolver(args.zone,args.glob)
logger = DNSLogger(args.log,args.log_prefix)
print("Starting Zone Resolver (%s:%d) [%s]" % (
args.address or "*",
args.port,
"UDP/TCP" if args.tcp else "UDP"))
for rr in resolver.zone:
print(" | ",rr[2].toZone(),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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