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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)
def endswith(domain, labels):
return domain.endswith("." + labels) or domain == labels
############################################################################
# Respond to a DNS query.
# For good. it serves:
# zoop.boing.good. NS ns3.good.
# icky.ptang.zoop.boing.good. NS a.bit.longer.ns.name.good.
# it responds properly (with NODATA empty response) to non-empty terminals
#
# For slow. it works the same as for good., but each response is delayed by 400 milliseconds
#
# For bad. it works the same as for good., but returns NXDOMAIN to non-empty terminals
#
# For ugly. it works the same as for good., but returns garbage to non-empty terminals
#
# For stale. it serves:
# a.b.stale. IN TXT peekaboo (resolver did not do qname minimization)
############################################################################
def create_response(msg):
m = dns.message.from_wire(msg)
qname = m.question[0].name.to_text()
lqname = qname.lower()
labels = lqname.split(".")
suffix = ""
# get qtype
rrtype = m.question[0].rdtype
typename = dns.rdatatype.to_text(rrtype)
if typename == "A" or typename == "AAAA":
typename = "ADDR"
bad = False
ugly = False
slow = False
# log this query
with open("query.log", "a") as f:
f.write("%s %s\n" % (typename, lqname))
print("%s %s" % (typename, lqname), end=" ")
r = dns.message.make_response(m)
r.set_rcode(NOERROR)
ip6req = False
if endswith(lqname, "bad."):
bad = True
suffix = "bad."
lqname = lqname[:-4]
elif endswith(lqname, "ugly."):
ugly = True
suffix = "ugly."
lqname = lqname[:-5]
elif endswith(lqname, "good."):
suffix = "good."
lqname = lqname[:-5]
elif endswith(lqname, "slow."):
slow = True
suffix = "slow."
lqname = lqname[:-5]
elif endswith(lqname, "8.2.6.0.1.0.0.2.ip6.arpa."):
ip6req = True
elif endswith(lqname, "a.b.stale."):
if lqname == "a.b.stale.":
if rrtype == TXT:
# Direct query.
r.answer.append(dns.rrset.from_text(lqname, 1, IN, TXT, "peekaboo"))
r.flags |= dns.flags.AA
elif rrtype == NS:
# NS a.b.
r.answer.append(dns.rrset.from_text(lqname, 1, IN, NS, "ns.a.b.stale."))
r.additional.append(
dns.rrset.from_text("ns.a.b.stale.", 1, IN, A, "10.53.0.3")
)
r.flags |= dns.flags.AA
elif rrtype == SOA:
# SOA a.b.
r.answer.append(
dns.rrset.from_text(
lqname, 1, IN, SOA, "a.b.stale. hostmaster.a.b.stale. 1 2 3 4 5"
)
)
r.flags |= dns.flags.AA
else:
# NODATA.
r.authority.append(
dns.rrset.from_text(
lqname, 1, IN, SOA, "a.b.stale. hostmaster.a.b.stale. 1 2 3 4 5"
)
)
else:
r.authority.append(
dns.rrset.from_text(
lqname, 1, IN, SOA, "a.b.stale. hostmaster.a.b.stale. 1 2 3 4 5"
)
)
r.set_rcode(NXDOMAIN)
# NXDOMAIN.
return r
else:
r.set_rcode(REFUSED)
return r
# Good/bad differs only in how we treat non-empty terminals
if lqname == "zoop.boing." and rrtype == NS:
r.answer.append(
dns.rrset.from_text(lqname + suffix, 1, IN, NS, "ns3." + suffix)
)
r.flags |= dns.flags.AA
elif endswith(lqname, "icky.ptang.zoop.boing."):
r.authority.append(
dns.rrset.from_text(
"icky.ptang.zoop.boing." + suffix,
1,
IN,
NS,
"a.bit.longer.ns.name." + suffix,
)
)
elif endswith("icky.ptang.zoop.boing.", lqname):
r.authority.append(
dns.rrset.from_text(
"zoop.boing." + suffix,
1,
IN,
SOA,
"ns3." + suffix + " hostmaster.arpa. 2018050100 1 1 1 1",
)
)
if bad:
r.set_rcode(NXDOMAIN)
if ugly:
r.set_rcode(FORMERR)
elif endswith(lqname, "zoop.boing."):
r.authority.append(
dns.rrset.from_text(
"zoop.boing." + suffix,
1,
IN,
SOA,
"ns3." + suffix + " hostmaster.arpa. 2018050100 1 1 1 1",
)
)
r.set_rcode(NXDOMAIN)
elif ip6req:
r.authority.append(
dns.rrset.from_text(
"1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa.", 60, IN, NS, "ns4.good."
)
)
r.additional.append(dns.rrset.from_text("ns4.good.", 60, IN, A, "10.53.0.4"))
else:
r.set_rcode(REFUSED)
if slow:
time.sleep(0.4)
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 = "10.53.0.3"
ip6 = "fd92:7065:b8e:ffff::3"
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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