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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.
import os
import select
import signal
import socket
import sys
import time
import dns.flags
import dns.message
def port():
env_port = os.getenv("PORT")
if env_port is None:
env_port = 5300
else:
env_port = int(env_port)
return env_port
def udp_listen(port):
udp = socket.socket(type=socket.SOCK_DGRAM)
udp.bind(("10.53.0.3", port))
return udp
def tcp_listen(port):
tcp = socket.socket(type=socket.SOCK_STREAM)
tcp.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
tcp.bind(("10.53.0.3", port))
tcp.listen(100)
return tcp
def udp_tc_once(udp):
qrybytes, clientaddr = udp.recvfrom(65535)
qry = dns.message.from_wire(qrybytes)
answ = dns.message.make_response(qry)
answ.flags |= dns.flags.TC
answbytes = answ.to_wire()
udp.sendto(answbytes, clientaddr)
def tcp_once(tcp):
csock, _clientaddr = tcp.accept()
time.sleep(5)
csock.close()
def sigterm(signum, frame):
os.remove("ans.pid")
sys.exit(0)
def write_pid():
with open("ans.pid", "w") as f:
pid = os.getpid()
f.write("{}".format(pid))
signal.signal(signal.SIGTERM, sigterm)
write_pid()
udp = udp_listen(port())
tcp = tcp_listen(port())
input = [udp, tcp]
while True:
try:
inputready, outputready, exceptready = select.select(input, [], [])
except select.error:
break
except socket.error:
break
except KeyboardInterrupt:
break
for s in inputready:
if s == udp:
udp_tc_once(udp)
if s == tcp:
tcp_once(tcp)
sigterm(signal.SIGTERM, 0)
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