1# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
2#
3# SPDX-License-Identifier: MPL-2.0
4#
5# This Source Code Form is subject to the terms of the Mozilla Public
6# License, v. 2.0.  If a copy of the MPL was not distributed with this
7# file, you can obtain one at https://mozilla.org/MPL/2.0/.
8#
9# See the COPYRIGHT file distributed with this work for additional
10# information regarding copyright ownership.
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
34def endswith(domain, labels):
35    return domain.endswith("." + labels) or domain == labels
36
37############################################################################
38# Respond to a DNS query.
39# For good. it serves:
40# icky.ptang.zoop.boing.good. NS a.bit.longer.ns.name.
41# icky.icky.icky.ptang.zoop.boing.good. A 192.0.2.1
42# more.icky.icky.icky.ptang.zoop.boing.good. A 192.0.2.2
43# it responds properly (with NODATA empty response) to non-empty terminals
44#
45# For slow. it works the same as for good., but each response is delayed by 400 milliseconds
46#
47# For bad. it works the same as for good., but returns NXDOMAIN to non-empty terminals
48#
49# For ugly. it works the same as for good., but returns garbage to non-empty terminals
50#
51# For stale. it serves:
52# a.b.stale. IN TXT hooray (resolver did do qname minimization)
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    slow = False
67    ugly = 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    ip6req = False
78
79    if endswith(lqname, "bad."):
80        bad = True
81        suffix = "bad."
82        lqname = lqname[:-4]
83    elif endswith(lqname, "ugly."):
84        ugly = True
85        suffix = "ugly."
86        lqname = lqname[:-5]
87    elif endswith(lqname, "good."):
88        suffix = "good."
89        lqname = lqname[:-5]
90    elif endswith(lqname, "slow."):
91        slow = True
92        suffix = "slow."
93        lqname = lqname[:-5]
94    elif endswith(lqname, "1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa."):
95        ip6req = True
96    elif endswith(lqname, "b.stale."):
97        if lqname == "a.b.stale.":
98            if rrtype == TXT:
99                # Direct query.
100                r.answer.append(dns.rrset.from_text(lqname, 1, IN, TXT, "hooray"))
101                r.flags |= dns.flags.AA
102            elif rrtype == NS:
103                # NS a.b.
104                r.answer.append(dns.rrset.from_text(lqname, 1, IN, NS, "ns.a.b.stale."))
105                r.additional.append(dns.rrset.from_text("ns.a.b.stale.", 1, IN, A, "10.53.0.3"))
106                r.flags |= dns.flags.AA
107            elif rrtype == SOA:
108                # SOA a.b.
109                r.answer.append(dns.rrset.from_text(lqname, 1, IN, SOA, "a.b.stale. hostmaster.a.b.stale. 1 2 3 4 5"))
110                r.flags |= dns.flags.AA
111            else:
112                # NODATA.
113                r.authority.append(dns.rrset.from_text(lqname, 1, IN, SOA, "a.b.stale. hostmaster.a.b.stale. 1 2 3 4 5"))
114        elif lqname == "b.stale.":
115            if rrtype == NS:
116                # NS b.
117                r.answer.append(dns.rrset.from_text(lqname, 1, IN, NS, "ns.b.stale."))
118                r.additional.append(dns.rrset.from_text("ns.b.stale.", 1, IN, A, "10.53.0.4"))
119                r.flags |= dns.flags.AA
120            elif rrtype == SOA:
121                # SOA b.
122                r.answer.append(dns.rrset.from_text(lqname, 1, IN, SOA, "b.stale. hostmaster.b.stale. 1 2 3 4 5"))
123                r.flags |= dns.flags.AA
124            else:
125                # NODATA.
126                r.authority.append(dns.rrset.from_text(lqname, 1, IN, SOA, "b.stale. hostmaster.b.stale. 1 2 3 4 5"))
127        else:
128            r.authority.append(dns.rrset.from_text(lqname, 1, IN, SOA, "b.stale. hostmaster.b.stale. 1 2 3 4 5"))
129            r.set_rcode(NXDOMAIN)
130            # NXDOMAIN.
131        return r
132    else:
133        r.set_rcode(REFUSED)
134        return r
135
136    # Good/bad differs only in how we treat non-empty terminals
137    if lqname == "icky.icky.icky.ptang.zoop.boing." and rrtype == A:
138        r.answer.append(dns.rrset.from_text(lqname + suffix, 1, IN, A, "192.0.2.1"))
139        r.flags |= dns.flags.AA
140    elif lqname == "more.icky.icky.icky.ptang.zoop.boing." and rrtype == A:
141        r.answer.append(dns.rrset.from_text(lqname + suffix, 1, IN, A, "192.0.2.2"))
142        r.flags |= dns.flags.AA
143    elif lqname == "icky.ptang.zoop.boing." and rrtype == NS:
144        r.answer.append(dns.rrset.from_text(lqname + suffix, 1, IN, NS, "a.bit.longer.ns.name."+suffix))
145        r.flags |= dns.flags.AA
146    elif endswith(lqname, "icky.ptang.zoop.boing."):
147        r.authority.append(dns.rrset.from_text("icky.ptang.zoop.boing." + suffix, 1, IN, SOA, "ns2." + suffix + " hostmaster.arpa. 2018050100 1 1 1 1"))
148        if bad or not endswith("more.icky.icky.icky.ptang.zoop.boing.", lqname):
149            r.set_rcode(NXDOMAIN)
150        if ugly:
151            r.set_rcode(FORMERR)
152    elif ip6req:
153        r.flags |= dns.flags.AA
154        if lqname == "test1.test2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.9.0.9.4.1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa." and rrtype == TXT:
155            r.answer.append(dns.rrset.from_text("test1.test2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.9.0.9.4.1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa.", 1, IN, TXT, "long_ip6_name"))
156        elif endswith("0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.9.0.9.4.1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa.", lqname):
157            #NODATA answer
158            r.authority.append(dns.rrset.from_text("1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa.", 60, IN, SOA, "ns4.good. hostmaster.arpa. 2018050100 120 30 320 16"))
159        else:
160            # NXDOMAIN
161            r.authority.append(dns.rrset.from_text("1.1.1.1.8.2.6.0.1.0.0.2.ip6.arpa.", 60, IN, SOA, "ns4.good. hostmaster.arpa. 2018050100 120 30 320 16"))
162            r.set_rcode(NXDOMAIN)
163    else:
164        r.set_rcode(REFUSED)
165
166    if slow:
167        time.sleep(0.4)
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 = "10.53.0.4"
185ip6 = "fd92:7065:b8e:ffff::4"
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