c9cb8ae9eb
This patch is strictly the result of: $ black $(git ls-files '*.py') There have been no manual changes.
402 lines
13 KiB
Python
Executable File
402 lines
13 KiB
Python
Executable File
# 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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def endswith(domain, labels):
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return domain.endswith("." + labels) or domain == labels
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############################################################################
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# Respond to a DNS query.
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# For good. it serves:
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# ns2.good. IN A 10.53.0.2
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# zoop.boing.good. NS ns3.good.
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# ns3.good. IN A 10.53.0.3
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# too.many.labels.a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z.good. A 192.0.2.2
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# it responds properly (with NODATA empty response) to non-empty terminals
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#
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# For slow. it works the same as for good., but each response is delayed by 400 milliseconds
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#
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# For bad. it works the same as for good., but returns NXDOMAIN to non-empty terminals
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#
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# For ugly. it works the same as for good., but returns garbage to non-empty terminals
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#
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# For 1.0.0.2.ip6.arpa it serves
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# 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.f.4.0.1.0.0.2.ip6.arpa. IN PTR nee.com.
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# 8.2.6.0.1.0.0.2.ip6.arpa IN NS ns3.good
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# 1.0.0.2.ip6.arpa. IN NS ns2.good
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# ip6.arpa. IN NS ns2.good
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#
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# For stale. it serves:
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# a.b. NS ns.a.b.stale.
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# ns.a.b.stale. IN A 10.53.0.3
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# b. NS ns.b.stale.
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# ns.b.stale. IN A 10.53.0.4
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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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lqname = qname.lower()
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labels = lqname.split(".")
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# get qtype
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rrtype = m.question[0].rdtype
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typename = dns.rdatatype.to_text(rrtype)
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if typename == "A" or typename == "AAAA":
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typename = "ADDR"
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bad = False
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ugly = False
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slow = False
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# log this query
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with open("query.log", "a") as f:
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f.write("%s %s\n" % (typename, lqname))
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print("%s %s" % (typename, lqname), end=" ")
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r = dns.message.make_response(m)
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r.set_rcode(NOERROR)
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if endswith(lqname, "1.0.0.2.ip6.arpa."):
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# Direct query - give direct answer
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if endswith(lqname, "8.2.6.0.1.0.0.2.ip6.arpa."):
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# Delegate to ns3
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r.authority.append(
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dns.rrset.from_text(
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"8.2.6.0.1.0.0.2.ip6.arpa.", 60, IN, NS, "ns3.good."
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)
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)
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r.additional.append(
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dns.rrset.from_text("ns3.good.", 60, IN, A, "10.53.0.3")
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)
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elif (
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lqname
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== "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.f.4.0.1.0.0.2.ip6.arpa."
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and rrtype == PTR
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):
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# Direct query - give direct answer
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r.answer.append(
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dns.rrset.from_text(
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"1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.f.4.0.1.0.0.2.ip6.arpa.",
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1,
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IN,
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PTR,
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"nee.com.",
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)
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)
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r.flags |= dns.flags.AA
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elif lqname == "1.0.0.2.ip6.arpa." and rrtype == NS:
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# NS query at the apex
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r.answer.append(
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dns.rrset.from_text("1.0.0.2.ip6.arpa.", 30, IN, NS, "ns2.good.")
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)
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r.flags |= dns.flags.AA
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elif endswith(
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"1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.f.4.0.1.0.0.2.ip6.arpa.",
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lqname,
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):
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# NODATA answer
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r.authority.append(
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dns.rrset.from_text(
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"1.0.0.2.ip6.arpa.",
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30,
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IN,
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SOA,
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"ns2.good. hostmaster.arpa. 2018050100 1 1 1 1",
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)
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)
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else:
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# NXDOMAIN
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r.authority.append(
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dns.rrset.from_text(
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"1.0.0.2.ip6.arpa.",
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30,
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IN,
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SOA,
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"ns2.good. hostmaster.arpa. 2018050100 1 1 1 1",
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)
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)
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r.set_rcode(NXDOMAIN)
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return r
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elif endswith(lqname, "ip6.arpa."):
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if lqname == "ip6.arpa." and rrtype == NS:
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# NS query at the apex
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r.answer.append(dns.rrset.from_text("ip6.arpa.", 30, IN, NS, "ns2.good."))
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r.flags |= dns.flags.AA
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elif endswith("1.0.0.2.ip6.arpa.", lqname):
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# NODATA answer
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r.authority.append(
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dns.rrset.from_text(
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"ip6.arpa.",
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30,
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IN,
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SOA,
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"ns2.good. hostmaster.arpa. 2018050100 1 1 1 1",
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)
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)
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else:
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# NXDOMAIN
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r.authority.append(
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dns.rrset.from_text(
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"ip6.arpa.",
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30,
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IN,
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SOA,
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"ns2.good. hostmaster.arpa. 2018050100 1 1 1 1",
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)
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)
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r.set_rcode(NXDOMAIN)
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return r
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elif endswith(lqname, "stale."):
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if endswith(lqname, "a.b.stale."):
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# Delegate to ns.a.b.stale.
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r.authority.append(
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dns.rrset.from_text("a.b.stale.", 2, IN, NS, "ns.a.b.stale.")
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)
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r.additional.append(
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dns.rrset.from_text("ns.a.b.stale.", 2, IN, A, "10.53.0.3")
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)
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elif endswith(lqname, "b.stale."):
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# Delegate to ns.b.stale.
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r.authority.append(
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dns.rrset.from_text("b.stale.", 2, IN, NS, "ns.b.stale.")
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)
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r.additional.append(
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dns.rrset.from_text("ns.b.stale.", 2, IN, A, "10.53.0.4")
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)
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elif lqname == "stale." and rrtype == NS:
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# NS query at the apex.
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r.answer.append(dns.rrset.from_text("stale.", 2, IN, NS, "ns2.stale."))
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r.flags |= dns.flags.AA
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elif lqname == "stale." and rrtype == SOA:
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# SOA query at the apex.
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r.answer.append(
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dns.rrset.from_text(
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"stale.", 2, IN, SOA, "ns2.stale. hostmaster.stale. 1 2 3 4 5"
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)
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)
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r.flags |= dns.flags.AA
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elif lqname == "stale.":
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# NODATA answer
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r.authority.append(
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dns.rrset.from_text(
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"stale.", 2, IN, SOA, "ns2.stale. hostmaster.arpa. 1 2 3 4 5"
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)
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)
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else:
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# NXDOMAIN
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r.authority.append(
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dns.rrset.from_text(
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"stale.", 2, IN, SOA, "ns2.stale. hostmaster.arpa. 1 2 3 4 5"
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)
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)
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r.set_rcode(NXDOMAIN)
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return r
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elif endswith(lqname, "bad."):
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bad = True
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suffix = "bad."
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lqname = lqname[:-4]
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elif endswith(lqname, "ugly."):
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ugly = True
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suffix = "ugly."
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lqname = lqname[:-5]
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elif endswith(lqname, "good."):
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suffix = "good."
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lqname = lqname[:-5]
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elif endswith(lqname, "slow."):
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slow = True
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suffix = "slow."
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lqname = lqname[:-5]
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elif endswith(lqname, "fwd."):
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suffix = "fwd."
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lqname = lqname[:-4]
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else:
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r.set_rcode(REFUSED)
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return r
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# Good/bad/ugly differs only in how we treat non-empty terminals
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if endswith(lqname, "zoop.boing."):
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r.authority.append(
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dns.rrset.from_text("zoop.boing." + suffix, 1, IN, NS, "ns3." + suffix)
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)
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elif (
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lqname == "many.labels.a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z."
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and rrtype == A
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):
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r.answer.append(dns.rrset.from_text(lqname + suffix, 1, IN, A, "192.0.2.2"))
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r.flags |= dns.flags.AA
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elif lqname == "" and rrtype == NS:
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r.answer.append(dns.rrset.from_text(suffix, 30, IN, NS, "ns2." + suffix))
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r.flags |= dns.flags.AA
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elif lqname == "ns2." and rrtype == A:
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r.answer.append(dns.rrset.from_text("ns2." + suffix, 30, IN, A, "10.53.0.2"))
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r.flags |= dns.flags.AA
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elif lqname == "ns2." and rrtype == AAAA:
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r.answer.append(
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dns.rrset.from_text("ns2." + suffix, 30, IN, AAAA, "fd92:7065:b8e:ffff::2")
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)
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r.flags |= dns.flags.AA
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elif lqname == "ns3." and rrtype == A:
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r.answer.append(dns.rrset.from_text("ns3." + suffix, 30, IN, A, "10.53.0.3"))
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r.flags |= dns.flags.AA
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elif lqname == "ns3." and rrtype == AAAA:
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r.answer.append(
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dns.rrset.from_text("ns3." + suffix, 30, IN, AAAA, "fd92:7065:b8e:ffff::3")
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)
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r.flags |= dns.flags.AA
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elif lqname == "ns4." and rrtype == A:
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r.answer.append(dns.rrset.from_text("ns4." + suffix, 30, IN, A, "10.53.0.4"))
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r.flags |= dns.flags.AA
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elif lqname == "ns4." and rrtype == AAAA:
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r.answer.append(
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dns.rrset.from_text("ns4." + suffix, 30, IN, AAAA, "fd92:7065:b8e:ffff::4")
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)
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r.flags |= dns.flags.AA
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elif lqname == "a.bit.longer.ns.name." and rrtype == A:
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r.answer.append(
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dns.rrset.from_text("a.bit.longer.ns.name." + suffix, 1, IN, A, "10.53.0.4")
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)
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r.flags |= dns.flags.AA
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elif lqname == "a.bit.longer.ns.name." and rrtype == AAAA:
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r.answer.append(
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dns.rrset.from_text(
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"a.bit.longer.ns.name." + suffix, 1, IN, AAAA, "fd92:7065:b8e:ffff::4"
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)
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)
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r.flags |= dns.flags.AA
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else:
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r.authority.append(
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dns.rrset.from_text(
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suffix,
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1,
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IN,
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SOA,
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"ns2." + suffix + " hostmaster.arpa. 2018050100 1 1 1 1",
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)
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)
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if bad or not (
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endswith("icky.icky.icky.ptang.zoop.boing.", lqname)
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or endswith(
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"many.labels.a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z.",
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lqname,
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)
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or endswith("a.bit.longer.ns.name.", lqname)
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):
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r.set_rcode(NXDOMAIN)
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if ugly:
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r.set_rcode(FORMERR)
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if slow:
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time.sleep(0.2)
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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 = "10.53.0.2"
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ip6 = "fd92:7065:b8e:ffff::2"
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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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