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#!/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=320)
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()
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