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# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
#
# SPDX-License-Identifier: MPL-2.0
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, you can obtain one at https://mozilla.org/MPL/2.0/.
#
# See the COPYRIGHT file distributed with this work for additional
# information regarding copyright ownership.
from __future__ import print_function
import os
import sys
import signal
import socket
import select
from datetime import datetime, timedelta
import time
import functools
import dns, dns.message, dns.query, dns.flags
from dns.rdatatype import *
from dns.rdataclass import *
from dns.rcode import *
from dns.name import *
# Log query to file
def logquery(type, qname):
with open("qlog", "a") as f:
f.write("%s %s\n", type, qname)
############################################################################
# Respond to a DNS query.
############################################################################
def create_response(msg):
m = dns.message.from_wire(msg)
qname = m.question[0].name.to_text()
rrtype = m.question[0].rdtype
typename = dns.rdatatype.to_text(rrtype)
with open("query.log", "a") as f:
f.write("%s %s\n" % (typename, qname))
print("%s %s" % (typename, qname), end=" ")
r = dns.message.make_response(m)
r.set_rcode(NOERROR)
if rrtype == A:
tld = qname.split(".")[-2] + "."
ns = "local." + tld
r.answer.append(dns.rrset.from_text(qname, 300, IN, A, "10.53.0.11"))
r.answer.append(dns.rrset.from_text(tld, 300, IN, NS, "local." + tld))
r.additional.append(dns.rrset.from_text(ns, 300, IN, A, "10.53.0.11"))
elif rrtype == NS:
r.answer.append(dns.rrset.from_text(qname, 300, IN, NS, "."))
elif rrtype == SOA:
r.answer.append(dns.rrset.from_text(qname, 300, IN, SOA, ". . 0 0 0 0 0"))
else:
r.authority.append(dns.rrset.from_text(qname, 300, IN, SOA, ". . 0 0 0 0 0"))
r.flags |= dns.flags.AA
return r
def sigterm(signum, frame):
print("Shutting down now...")
os.remove("ans.pid")
running = False
sys.exit(0)
############################################################################
# Main
#
# Set up responder and control channel, open the pid file, and start
# the main loop, listening for queries on the query channel or commands
# on the control channel and acting on them.
############################################################################
ip4 = "10.53.0.11"
ip6 = "fd92:7065:b8e:ffff::11"
try:
port = int(os.environ["PORT"])
except:
port = 5300
query4_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
query4_socket.bind((ip4, port))
havev6 = True
try:
query6_socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
try:
query6_socket.bind((ip6, port))
except:
query6_socket.close()
havev6 = False
except:
havev6 = False
signal.signal(signal.SIGTERM, sigterm)
f = open("ans.pid", "w")
pid = os.getpid()
print(pid, file=f)
f.close()
running = True
print("Listening on %s port %d" % (ip4, port))
if havev6:
print("Listening on %s port %d" % (ip6, port))
print("Ctrl-c to quit")
if havev6:
input = [query4_socket, query6_socket]
else:
input = [query4_socket]
while running:
try:
inputready, outputready, exceptready = select.select(input, [], [])
except select.error as e:
break
except socket.error as e:
break
except KeyboardInterrupt:
break
for s in inputready:
if s == query4_socket or s == query6_socket:
print(
"Query received on %s" % (ip4 if s == query4_socket else ip6), end=" "
)
# Handle incoming queries
msg = s.recvfrom(65535)
rsp = create_response(msg[0])
if rsp:
print(dns.rcode.to_text(rsp.rcode()))
s.sendto(rsp.to_wire(), msg[1])
else:
print("NO RESPONSE")
if not running:
break
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