152 lines
4.3 KiB
Python
152 lines
4.3 KiB
Python
# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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#
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# SPDX-License-Identifier: MPL-2.0
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#
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# This Source Code Form is subject to the terms of the Mozilla Public
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# License, v. 2.0. If a copy of the MPL was not distributed with this
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# file, you can obtain one at https://mozilla.org/MPL/2.0/.
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#
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# See the COPYRIGHT file distributed with this work for additional
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# information regarding copyright ownership.
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from __future__ import print_function
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import os
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import sys
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import signal
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import socket
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import select
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from datetime import datetime, timedelta
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import time
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import functools
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import dns, dns.message, dns.query, dns.flags
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from dns.rdatatype import *
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from dns.rdataclass import *
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from dns.rcode import *
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from dns.name import *
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# Log query to file
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def logquery(type, qname):
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with open("qlog", "a") as f:
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f.write("%s %s\n", type, qname)
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############################################################################
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# Respond to a DNS query.
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# If there are EDNS options present return FORMERR copying the OPT record.
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# Otherwise:
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# SOA gets a unsigned response.
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# NS gets a unsigned response.
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# A gets a unsigned response.
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# All other types get a unsigned NODATA response.
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############################################################################
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def create_response(msg):
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m = dns.message.from_wire(msg)
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qname = m.question[0].name.to_text()
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rrtype = m.question[0].rdtype
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typename = dns.rdatatype.to_text(rrtype)
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with open("query.log", "a") as f:
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f.write("%s %s\n" % (typename, qname))
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print("%s %s" % (typename, qname), end=" ")
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if m.edns != -1 and len(m.options) != 0:
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r = dns.message.make_response(m)
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r.use_edns(
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edns=m.edns, ednsflags=m.ednsflags, payload=m.payload, options=m.options
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)
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r.set_rcode(FORMERR)
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else:
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r = dns.message.make_response(m)
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r.set_rcode(NOERROR)
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if rrtype == A:
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r.answer.append(dns.rrset.from_text(qname, 1, IN, A, "10.53.0.10"))
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elif rrtype == NS:
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r.answer.append(dns.rrset.from_text(qname, 1, IN, NS, "."))
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elif rrtype == SOA:
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r.answer.append(dns.rrset.from_text(qname, 1, IN, SOA, ". . 0 0 0 0 0"))
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else:
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r.authority.append(dns.rrset.from_text(qname, 1, IN, SOA, ". . 0 0 0 0 0"))
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r.flags |= dns.flags.AA
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return r
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def sigterm(signum, frame):
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print("Shutting down now...")
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os.remove("ans.pid")
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running = False
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sys.exit(0)
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############################################################################
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# Main
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#
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# Set up responder and control channel, open the pid file, and start
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# the main loop, listening for queries on the query channel or commands
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# on the control channel and acting on them.
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############################################################################
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ip4 = "10.53.0.10"
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ip6 = "fd92:7065:b8e:ffff::10"
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try:
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port = int(os.environ["PORT"])
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except:
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port = 5300
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query4_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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query4_socket.bind((ip4, port))
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havev6 = True
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try:
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query6_socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
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try:
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query6_socket.bind((ip6, port))
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except:
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query6_socket.close()
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havev6 = False
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except:
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havev6 = False
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signal.signal(signal.SIGTERM, sigterm)
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f = open("ans.pid", "w")
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pid = os.getpid()
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print(pid, file=f)
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f.close()
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running = True
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print("Listening on %s port %d" % (ip4, port))
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if havev6:
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print("Listening on %s port %d" % (ip6, port))
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print("Ctrl-c to quit")
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if havev6:
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input = [query4_socket, query6_socket]
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else:
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input = [query4_socket]
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while running:
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try:
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inputready, outputready, exceptready = select.select(input, [], [])
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except select.error as e:
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break
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except socket.error as e:
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break
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except KeyboardInterrupt:
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break
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for s in inputready:
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if s == query4_socket or s == query6_socket:
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print(
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"Query received on %s" % (ip4 if s == query4_socket else ip6), end=" "
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)
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# Handle incoming queries
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msg = s.recvfrom(65535)
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rsp = create_response(msg[0])
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if rsp:
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print(dns.rcode.to_text(rsp.rcode()))
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s.sendto(rsp.to_wire(), msg[1])
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else:
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print("NO RESPONSE")
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if not running:
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break
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