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
|
#!/usr/bin/env python3
# Copyright (c) 2015-2019 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Test node responses to invalid network messages."""
import asyncio
import struct
import sys
from test_framework import messages
from test_framework.mininode import P2PDataStore, NetworkThread
from test_framework.test_framework import BitcoinTestFramework
class msg_unrecognized:
"""Nonsensical message. Modeled after similar types in test_framework.messages."""
command = b'badmsg'
def __init__(self, *, str_data):
self.str_data = str_data.encode() if not isinstance(str_data, bytes) else str_data
def serialize(self):
return messages.ser_string(self.str_data)
def __repr__(self):
return "{}(data={})".format(self.command, self.str_data)
class InvalidMessagesTest(BitcoinTestFramework):
def set_test_params(self):
self.num_nodes = 1
self.setup_clean_chain = True
def run_test(self):
"""
. Test msg header
0. Send a bunch of large (4MB) messages of an unrecognized type. Check to see
that it isn't an effective DoS against the node.
1. Send an oversized (4MB+) message and check that we're disconnected.
2. Send a few messages with an incorrect data size in the header, ensure the
messages are ignored.
"""
self.test_magic_bytes()
self.test_checksum()
self.test_size()
self.test_command()
node = self.nodes[0]
self.node = node
node.add_p2p_connection(P2PDataStore())
conn2 = node.add_p2p_connection(P2PDataStore())
msg_limit = 4 * 1000 * 1000 # 4MB, per MAX_PROTOCOL_MESSAGE_LENGTH
valid_data_limit = msg_limit - 5 # Account for the 4-byte length prefix
#
# 0.
#
# Send as large a message as is valid, ensure we aren't disconnected but
# also can't exhaust resources.
#
msg_at_size = msg_unrecognized(str_data="b" * valid_data_limit)
assert len(msg_at_size.serialize()) == msg_limit
self.log.info("Sending a bunch of large, junk messages to test memory exhaustion. May take a bit...")
# Run a bunch of times to test for memory exhaustion.
for _ in range(80):
node.p2p.send_message(msg_at_size)
# Check that, even though the node is being hammered by nonsense from one
# connection, it can still service other peers in a timely way.
for _ in range(20):
conn2.sync_with_ping(timeout=2)
# Peer 1, despite serving up a bunch of nonsense, should still be connected.
self.log.info("Waiting for node to drop junk messages.")
node.p2p.sync_with_ping(timeout=400)
assert node.p2p.is_connected
#
# 1.
#
# Send an oversized message, ensure we're disconnected.
#
# Under macOS this test is skipped due to an unexpected error code
# returned from the closing socket which python/asyncio does not
# yet know how to handle.
#
if sys.platform != 'darwin':
msg_over_size = msg_unrecognized(str_data="b" * (valid_data_limit + 1))
assert len(msg_over_size.serialize()) == (msg_limit + 1)
# An unknown message type (or *any* message type) over
# MAX_PROTOCOL_MESSAGE_LENGTH should result in a disconnect.
node.p2p.send_message(msg_over_size)
node.p2p.wait_for_disconnect(timeout=4)
node.disconnect_p2ps()
conn = node.add_p2p_connection(P2PDataStore())
conn.wait_for_verack()
else:
self.log.info("Skipping test p2p_invalid_messages/1 (oversized message) under macOS")
#
# 2.
#
# Send messages with an incorrect data size in the header.
#
actual_size = 100
msg = msg_unrecognized(str_data="b" * actual_size)
# TODO: handle larger-than cases. I haven't been able to pin down what behavior to expect.
for wrong_size in (2, 77, 78, 79):
self.log.info("Sending a message with incorrect size of {}".format(wrong_size))
# Unmodified message should submit okay.
node.p2p.send_and_ping(msg)
# A message lying about its data size results in a disconnect when the incorrect
# data size is less than the actual size.
#
# TODO: why does behavior change at 78 bytes?
#
node.p2p.send_raw_message(self._tweak_msg_data_size(msg, wrong_size))
# For some reason unknown to me, we sometimes have to push additional data to the
# peer in order for it to realize a disconnect.
try:
node.p2p.send_message(messages.msg_ping(nonce=123123))
except IOError:
pass
node.p2p.wait_for_disconnect(timeout=10)
node.disconnect_p2ps()
node.add_p2p_connection(P2PDataStore())
# Node is still up.
conn = node.add_p2p_connection(P2PDataStore())
conn.sync_with_ping()
def test_magic_bytes(self):
conn = self.nodes[0].add_p2p_connection(P2PDataStore())
async def swap_magic_bytes():
conn._on_data = lambda: None # Need to ignore all incoming messages from now, since they come with "invalid" magic bytes
conn.magic_bytes = b'\x00\x11\x22\x32'
# Call .result() to block until the atomic swap is complete, otherwise
# we might run into races later on
asyncio.run_coroutine_threadsafe(swap_magic_bytes(), NetworkThread.network_event_loop).result()
with self.nodes[0].assert_debug_log(['PROCESSMESSAGE: INVALID MESSAGESTART ping']):
conn.send_message(messages.msg_ping(nonce=0xff))
conn.wait_for_disconnect(timeout=1)
self.nodes[0].disconnect_p2ps()
def test_checksum(self):
conn = self.nodes[0].add_p2p_connection(P2PDataStore())
with self.nodes[0].assert_debug_log(['CHECKSUM ERROR (badmsg, 2 bytes), expected 78df0a04 was ffffffff']):
msg = conn.build_message(msg_unrecognized(str_data="d"))
cut_len = (
4 + # magic
12 + # command
4 #len
)
# modify checksum
msg = msg[:cut_len] + b'\xff' * 4 + msg[cut_len + 4:]
self.nodes[0].p2p.send_raw_message(msg)
conn.sync_with_ping(timeout=1)
self.nodes[0].disconnect_p2ps()
def test_size(self):
conn = self.nodes[0].add_p2p_connection(P2PDataStore())
with self.nodes[0].assert_debug_log(['']):
msg = conn.build_message(msg_unrecognized(str_data="d"))
cut_len = (
4 + # magic
12 # command
)
# modify len to MAX_SIZE + 1
msg = msg[:cut_len] + struct.pack("<I", 0x02000000 + 1) + msg[cut_len + 4:]
self.nodes[0].p2p.send_raw_message(msg)
conn.wait_for_disconnect(timeout=1)
self.nodes[0].disconnect_p2ps()
def test_command(self):
conn = self.nodes[0].add_p2p_connection(P2PDataStore())
with self.nodes[0].assert_debug_log(['PROCESSMESSAGE: ERRORS IN HEADER']):
msg = msg_unrecognized(str_data="d")
msg.command = b'\xff' * 12
msg = conn.build_message(msg)
# Modify command
msg = msg[:7] + b'\x00' + msg[7 + 1:]
self.nodes[0].p2p.send_raw_message(msg)
conn.sync_with_ping(timeout=1)
self.nodes[0].disconnect_p2ps()
def _tweak_msg_data_size(self, message, wrong_size):
"""
Return a raw message based on another message but with an incorrect data size in
the message header.
"""
raw_msg = self.node.p2p.build_message(message)
bad_size_bytes = struct.pack("<I", wrong_size)
num_header_bytes_before_size = 4 + 12
# Replace the correct data size in the message with an incorrect one.
raw_msg_with_wrong_size = (
raw_msg[:num_header_bytes_before_size] +
bad_size_bytes +
raw_msg[(num_header_bytes_before_size + len(bad_size_bytes)):]
)
assert len(raw_msg) == len(raw_msg_with_wrong_size)
return raw_msg_with_wrong_size
if __name__ == '__main__':
InvalidMessagesTest().main()
|
