1############################################################################
2# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
3#
4# This Source Code Form is subject to the terms of the Mozilla Public
5# License, v. 2.0. If a copy of the MPL was not distributed with this
6# file, You can obtain one at http://mozilla.org/MPL/2.0/.
7#
8# See the COPYRIGHT file distributed with this work for additional
9# information regarding copyright ownership.
10############################################################################
11
12from __future__ import print_function
13import os
14import sys
15import signal
16import socket
17import select
18from datetime import datetime, timedelta
19import time
20import functools
21
22import dns, dns.message, dns.query, dns.flags
23from dns.rdatatype import *
24from dns.rdataclass import *
25from dns.rcode import *
26from dns.name import *
27
28
29# Log query to file
30def logquery(type, qname):
31    with open("qlog", "a") as f:
32        f.write("%s %s\n", type, qname)
33
34############################################################################
35# Respond to a DNS query.
36# For good. it serves:
37# ns2.good. IN A 10.53.0.2
38# zoop.boing.good. NS ns3.good.
39# ns3.good. IN A 10.53.0.3
40# 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
41# it responds properly (with NODATA empty response) to non-empty terminals
42#
43# For slow. it works the same as for good., but each response is delayed by 400 milliseconds
44#
45# For bad. it works the same as for good., but returns NXDOMAIN to non-empty terminals
46#
47# For ugly. it works the same as for good., but returns garbage to non-empty terminals
48#
49# For 1.0.0.2.ip6.arpa it serves
50# 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.
51# 1.0.0.2.ip6.arpa. IN NS ns2.good
52# ip6.arpa. IN NS ns2.good
53############################################################################
54def create_response(msg):
55    m = dns.message.from_wire(msg)
56    qname = m.question[0].name.to_text()
57    lqname = qname.lower()
58    labels = lqname.split('.')
59
60    # get qtype
61    rrtype = m.question[0].rdtype
62    typename = dns.rdatatype.to_text(rrtype)
63    if typename == "A" or typename == "AAAA":
64        typename = "ADDR"
65    bad = False
66    ugly = False
67    slow = False
68
69    # log this query
70    with open("query.log", "a") as f:
71        f.write("%s %s\n" % (typename, lqname))
72        print("%s %s" % (typename, lqname), end=" ")
73
74    r = dns.message.make_response(m)
75    r.set_rcode(NOERROR)
76
77    if lqname.endswith("1.0.0.2.ip6.arpa."):
78        # Direct query - give direct answer
79        if lqname == "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." and rrtype == PTR:
80            # Direct query - give direct answer
81            r.answer.append(dns.rrset.from_text("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.", 1, IN, PTR, "nee.com."))
82            r.flags |= dns.flags.AA
83        elif lqname == "1.0.0.2.ip6.arpa." and rrtype == NS:
84            # NS query at the apex
85            r.answer.append(dns.rrset.from_text("1.0.0.2.ip6.arpa.", 1, IN, NS, "ns2.good."))
86            r.flags |= dns.flags.AA
87        elif "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.".endswith(lqname):
88            # NODATA answer
89            r.authority.append(dns.rrset.from_text("1.0.0.2.ip6.arpa.", 1, IN, SOA, "ns2.good. hostmaster.arpa. 2018050100 1 1 1 1"))
90        else:
91            # NXDOMAIN
92            r.authority.append(dns.rrset.from_text("1.0.0.2.ip6.arpa.", 1, IN, SOA, "ns2.good. hostmaster.arpa. 2018050100 1 1 1 1"))
93            r.set_rcode(NXDOMAIN)
94        return r
95    elif lqname.endswith("ip6.arpa."):
96        if lqname == "ip6.arpa." and rrtype == NS:
97            # NS query at the apex
98            r.answer.append(dns.rrset.from_text("ip6.arpa.", 1, IN, NS, "ns2.good."))
99            r.flags |= dns.flags.AA
100        elif "1.0.0.2.ip6.arpa.".endswith(lqname):
101            # NODATA answer
102            r.authority.append(dns.rrset.from_text("ip6.arpa.", 1, IN, SOA, "ns2.good. hostmaster.arpa. 2018050100 1 1 1 1"))
103        else:
104            # NXDOMAIN
105            r.authority.append(dns.rrset.from_text("ip6.arpa.", 1, IN, SOA, "ns2.good. hostmaster.arpa. 2018050100 1 1 1 1"))
106            r.set_rcode(NXDOMAIN)
107        return r
108    elif lqname.endswith("bad."):
109        bad = True
110        suffix = "bad."
111        lqname = lqname[:-4]
112    elif lqname.endswith("ugly."):
113        ugly = True
114        suffix = "ugly."
115        lqname = lqname[:-5]
116    elif lqname.endswith("good."):
117        suffix = "good."
118        lqname = lqname[:-5]
119    elif lqname.endswith("slow."):
120        slow = True
121        suffix = "slow."
122        lqname = lqname[:-5]
123    elif lqname.endswith("fwd."):
124        suffix = "fwd."
125        lqname = lqname[:-4]
126    else:
127        r.set_rcode(REFUSED)
128        return r
129
130    # Good/bad/ugly differs only in how we treat non-empty terminals
131    if lqname.endswith("zoop.boing."):
132        r.authority.append(dns.rrset.from_text("zoop.boing." + suffix, 1, IN, NS, "ns3." + suffix))
133    elif 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." and rrtype == A:
134        r.answer.append(dns.rrset.from_text(lqname + suffix, 1, IN, A, "192.0.2.2"))
135        r.flags |= dns.flags.AA
136    elif lqname == "" and rrtype == NS:
137        r.answer.append(dns.rrset.from_text(suffix, 1, IN, NS, "ns2." + suffix))
138        r.flags |= dns.flags.AA
139    elif lqname == "ns2." and rrtype == A:
140        r.answer.append(dns.rrset.from_text("ns2."+suffix, 1, IN, A, "10.53.0.2"))
141        r.flags |= dns.flags.AA
142    elif lqname == "ns2." and rrtype == AAAA:
143        r.answer.append(dns.rrset.from_text("ns2."+suffix, 1, IN, AAAA, "fd92:7065:b8e:ffff::2"))
144        r.flags |= dns.flags.AA
145    elif lqname == "ns3." and rrtype == A:
146        r.answer.append(dns.rrset.from_text("ns3."+suffix, 1, IN, A, "10.53.0.3"))
147        r.flags |= dns.flags.AA
148    elif lqname == "ns3." and rrtype == AAAA:
149        r.answer.append(dns.rrset.from_text("ns3."+suffix, 1, IN, AAAA, "fd92:7065:b8e:ffff::3"))
150        r.flags |= dns.flags.AA
151    elif lqname == "a.bit.longer.ns.name." and rrtype == A:
152        r.answer.append(dns.rrset.from_text("a.bit.longer.ns.name."+suffix, 1, IN, A, "10.53.0.4"))
153        r.flags |= dns.flags.AA
154    elif lqname == "a.bit.longer.ns.name." and rrtype == AAAA:
155        r.answer.append(dns.rrset.from_text("a.bit.longer.ns.name."+suffix, 1, IN, AAAA, "fd92:7065:b8e:ffff::4"))
156        r.flags |= dns.flags.AA
157    else:
158        r.authority.append(dns.rrset.from_text(suffix, 1, IN, SOA, "ns2." + suffix + " hostmaster.arpa. 2018050100 1 1 1 1"))
159        if bad or not \
160            ("icky.icky.icky.ptang.zoop.boing.".endswith(lqname) or \
161             "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.".endswith(lqname) or \
162             "a.bit.longer.ns.name.".endswith(lqname)):
163            r.set_rcode(NXDOMAIN)
164        if ugly:
165            r.set_rcode(FORMERR)
166    if slow:
167        time.sleep(0.2)
168    return r
169
170
171def sigterm(signum, frame):
172    print ("Shutting down now...")
173    os.remove('ans.pid')
174    running = False
175    sys.exit(0)
176
177############################################################################
178# Main
179#
180# Set up responder and control channel, open the pid file, and start
181# the main loop, listening for queries on the query channel or commands
182# on the control channel and acting on them.
183############################################################################
184ip4 = "10.53.0.2"
185ip6 = "fd92:7065:b8e:ffff::2"
186
187try: port=int(os.environ['PORT'])
188except: port=5300
189
190query4_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
191query4_socket.bind((ip4, port))
192
193havev6 = True
194try:
195    query6_socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
196    try:
197        query6_socket.bind((ip6, port))
198    except:
199        query6_socket.close()
200        havev6 = False
201except:
202    havev6 = False
203
204signal.signal(signal.SIGTERM, sigterm)
205
206f = open('ans.pid', 'w')
207pid = os.getpid()
208print (pid, file=f)
209f.close()
210
211running = True
212
213print ("Listening on %s port %d" % (ip4, port))
214if havev6:
215    print ("Listening on %s port %d" % (ip6, port))
216print ("Ctrl-c to quit")
217
218if havev6:
219    input = [query4_socket, query6_socket]
220else:
221    input = [query4_socket]
222
223while running:
224    try:
225        inputready, outputready, exceptready = select.select(input, [], [])
226    except select.error as e:
227        break
228    except socket.error as e:
229        break
230    except KeyboardInterrupt:
231        break
232
233    for s in inputready:
234        if s == query4_socket or s == query6_socket:
235            print ("Query received on %s" %
236                    (ip4 if s == query4_socket else ip6), end=" ")
237            # Handle incoming queries
238            msg = s.recvfrom(65535)
239            rsp = create_response(msg[0])
240            if rsp:
241                print(dns.rcode.to_text(rsp.rcode()))
242                s.sendto(rsp.to_wire(), msg[1])
243            else:
244                print("NO RESPONSE")
245    if not running:
246        break
247