1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
|
"""Unit tests for zeroconf._listener"""
from __future__ import annotations
import logging
import unittest
import unittest.mock
from unittest.mock import MagicMock, patch
import zeroconf as r
from zeroconf import (
ServiceInfo,
Zeroconf,
_engine,
_listener,
const,
current_time_millis,
)
from zeroconf._protocol import outgoing
from zeroconf._protocol.incoming import DNSIncoming
from . import QuestionHistoryWithoutSuppression
log = logging.getLogger("zeroconf")
original_logging_level = logging.NOTSET
def setup_module():
global original_logging_level
original_logging_level = log.level
log.setLevel(logging.DEBUG)
def teardown_module():
if original_logging_level != logging.NOTSET:
log.setLevel(original_logging_level)
def test_guard_against_oversized_packets():
"""Ensure we do not process oversized packets.
These packets can quickly overwhelm the system.
"""
zc = Zeroconf(interfaces=["127.0.0.1"])
generated = r.DNSOutgoing(const._FLAGS_QR_RESPONSE)
for _i in range(5000):
generated.add_answer_at_time(
r.DNSText(
"packet{i}.local.",
const._TYPE_TXT,
const._CLASS_IN | const._CLASS_UNIQUE,
500,
b"path=/~paulsm/",
),
0,
)
try:
# We are patching to generate an oversized packet
with (
patch.object(outgoing, "_MAX_MSG_ABSOLUTE", 100000),
patch.object(outgoing, "_MAX_MSG_TYPICAL", 100000),
):
over_sized_packet = generated.packets()[0]
assert len(over_sized_packet) > const._MAX_MSG_ABSOLUTE
except AttributeError:
# cannot patch with cython
zc.close()
return
generated = r.DNSOutgoing(const._FLAGS_QR_RESPONSE)
okpacket_record = r.DNSText(
"okpacket.local.",
const._TYPE_TXT,
const._CLASS_IN | const._CLASS_UNIQUE,
500,
b"path=/~paulsm/",
)
generated.add_answer_at_time(
okpacket_record,
0,
)
ok_packet = generated.packets()[0]
# We cannot test though the network interface as some operating systems
# will guard against the oversized packet and we won't see it.
listener = _listener.AsyncListener(zc)
listener.transport = unittest.mock.MagicMock()
listener.datagram_received(ok_packet, ("127.0.0.1", const._MDNS_PORT))
assert zc.cache.async_get_unique(okpacket_record) is not None
listener.datagram_received(over_sized_packet, ("127.0.0.1", const._MDNS_PORT))
assert (
zc.cache.async_get_unique(
r.DNSText(
"packet0.local.",
const._TYPE_TXT,
const._CLASS_IN | const._CLASS_UNIQUE,
500,
b"path=/~paulsm/",
)
)
is None
)
logging.getLogger("zeroconf").setLevel(logging.INFO)
listener.datagram_received(over_sized_packet, ("::1", const._MDNS_PORT, 1, 1))
assert (
zc.cache.async_get_unique(
r.DNSText(
"packet0.local.",
const._TYPE_TXT,
const._CLASS_IN | const._CLASS_UNIQUE,
500,
b"path=/~paulsm/",
)
)
is None
)
zc.close()
def test_guard_against_duplicate_packets():
"""Ensure we do not process duplicate packets.
These packets can quickly overwhelm the system.
"""
zc = Zeroconf(interfaces=["127.0.0.1"])
zc.registry.async_add(
ServiceInfo(
"_http._tcp.local.",
"Test._http._tcp.local.",
server="Test._http._tcp.local.",
port=4,
)
)
zc.question_history = QuestionHistoryWithoutSuppression()
class SubListener(_listener.AsyncListener):
def handle_query_or_defer(
self,
msg: DNSIncoming,
addr: str,
port: int,
transport: _engine._WrappedTransport,
v6_flow_scope: tuple[()] | tuple[int, int] = (),
) -> None:
"""Handle a query or defer it for later processing."""
super().handle_query_or_defer(msg, addr, port, transport, v6_flow_scope)
listener = SubListener(zc)
listener.transport = MagicMock()
query = r.DNSOutgoing(const._FLAGS_QR_QUERY, multicast=True)
question = r.DNSQuestion("x._http._tcp.local.", const._TYPE_PTR, const._CLASS_IN)
query.add_question(question)
packet_with_qm_question = query.packets()[0]
query3 = r.DNSOutgoing(const._FLAGS_QR_QUERY, multicast=True)
question3 = r.DNSQuestion("x._ay._tcp.local.", const._TYPE_PTR, const._CLASS_IN)
query3.add_question(question3)
packet_with_qm_question2 = query3.packets()[0]
query2 = r.DNSOutgoing(const._FLAGS_QR_QUERY, multicast=True)
question2 = r.DNSQuestion("x._http._tcp.local.", const._TYPE_PTR, const._CLASS_IN)
question2.unicast = True
query2.add_question(question2)
packet_with_qu_question = query2.packets()[0]
addrs = ("1.2.3.4", 43)
with patch.object(listener, "handle_query_or_defer") as _handle_query_or_defer:
start_time = current_time_millis()
listener._process_datagram_at_time(
False,
len(packet_with_qm_question),
start_time,
packet_with_qm_question,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
# Now call with the same packet again and handle_query_or_defer should not fire
listener._process_datagram_at_time(
False,
len(packet_with_qm_question),
start_time,
packet_with_qm_question,
addrs,
)
_handle_query_or_defer.assert_not_called()
_handle_query_or_defer.reset_mock()
# Now walk time forward 1100 milliseconds
new_time = start_time + 1100
# Now call with the same packet again and handle_query_or_defer should fire
listener._process_datagram_at_time(
False,
len(packet_with_qm_question),
new_time,
packet_with_qm_question,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
# Now call with the different packet and handle_query_or_defer should fire
listener._process_datagram_at_time(
False,
len(packet_with_qm_question2),
new_time,
packet_with_qm_question2,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
# Now call with the different packet and handle_query_or_defer should fire
listener._process_datagram_at_time(
False,
len(packet_with_qm_question),
new_time,
packet_with_qm_question,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
# Now call with the different packet with qu question and handle_query_or_defer should fire
listener._process_datagram_at_time(
False,
len(packet_with_qu_question),
new_time,
packet_with_qu_question,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
# Now call again with the same packet that has a qu question and handle_query_or_defer should fire
listener._process_datagram_at_time(
False,
len(packet_with_qu_question),
new_time,
packet_with_qu_question,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
log.setLevel(logging.WARNING)
# Call with the QM packet again
listener._process_datagram_at_time(
False,
len(packet_with_qm_question),
new_time,
packet_with_qm_question,
addrs,
)
_handle_query_or_defer.assert_called_once()
_handle_query_or_defer.reset_mock()
# Now call with the same packet again and handle_query_or_defer should not fire
listener._process_datagram_at_time(
False,
len(packet_with_qm_question),
new_time,
packet_with_qm_question,
addrs,
)
_handle_query_or_defer.assert_not_called()
_handle_query_or_defer.reset_mock()
# Now call with garbage
listener._process_datagram_at_time(False, len(b"garbage"), new_time, b"garbage", addrs)
_handle_query_or_defer.assert_not_called()
_handle_query_or_defer.reset_mock()
zc.close()
|
