#!/usr/bin/env python3 # Copyright (c) 2015-2020 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 struct import sys from test_framework.messages import ( CBlockHeader, CInv, msg_ping, ser_string, msg_getdata, msg_headers, msg_inv, MSG_TX, ) from test_framework.mininode import ( P2PDataStore, P2PInterface ) from test_framework.test_framework import BitcoinTestFramework from test_framework.util import ( assert_equal, wait_until, ) class msg_unrecognized: """Nonsensical message. Modeled after similar types in test_framework.messages.""" msgtype = 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 ser_string(self.str_data) def __repr__(self): return "{}(data={})".format(self.msgtype, 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 (3MB) messages of an unrecognized type. Check to see that it isn't an effective DoS against the node. 1. Send an oversized (3MB+) 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_buffer() self.test_magic_bytes() self.test_checksum() self.test_size() self.test_msgtype() self.test_large_inv() node = self.nodes[0] self.node = node node.add_p2p_connection(P2PDataStore()) conn2 = node.add_p2p_connection(P2PDataStore()) msg_limit = 3 * 1024 * 1024 # 3MB, 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(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()) def test_buffer(self): self.log.info("Test message with header split across two buffers, should be received") conn = self.nodes[0].add_p2p_connection(P2PDataStore()) # Create valid message msg = conn.build_message(msg_ping(nonce=12345)) cut_pos = 12 # Chosen at an arbitrary position within the header # Send message in two pieces before = int(self.nodes[0].getnettotals()['totalbytesrecv']) conn.send_raw_message(msg[:cut_pos]) # Wait until node has processed the first half of the message wait_until(lambda: int(self.nodes[0].getnettotals()['totalbytesrecv']) != before) middle = int(self.nodes[0].getnettotals()['totalbytesrecv']) # If this assert fails, we've hit an unlikely race # where the test framework sent a message in between the two halves assert_equal(middle, before + cut_pos) conn.send_raw_message(msg[cut_pos:]) conn.sync_with_ping(timeout=1) self.nodes[0].disconnect_p2ps() def test_magic_bytes(self): conn = self.nodes[0].add_p2p_connection(P2PDataStore()) with self.nodes[0].assert_debug_log(['HEADER ERROR - MESSAGESTART (badmsg, 2 bytes), received ffffffff']): msg = conn.build_message(msg_unrecognized(str_data="d")) # modify magic bytes msg = b'\xff' * 4 + msg[4:] conn.send_raw_message(msg) conn.wait_for_disconnect(timeout=5) 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")) # Checksum is after start bytes (4B), message type (12B), len (4B) cut_len = 4 + 12 + 4 # 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(['HEADER ERROR - SIZE (badmsg, 33554433 bytes)']): msg = conn.build_message(msg_unrecognized(str_data="d")) cut_len = ( 4 + # magic 12 # msgtype ) # modify len to MAX_SIZE + 1 msg = msg[:cut_len] + struct.pack(" 20): message inv size() = 50001']): msg = msg_inv([CInv(MSG_TX, 1)] * 50001) conn.send_and_ping(msg) with self.nodes[0].assert_debug_log(['Misbehaving', '(20 -> 40): message getdata size() = 50001']): msg = msg_getdata([CInv(MSG_TX, 1)] * 50001) conn.send_and_ping(msg) with self.nodes[0].assert_debug_log(['Misbehaving', '(40 -> 60): headers message size = 2001']): msg = msg_headers([CBlockHeader()] * 2001) conn.send_and_ping(msg) 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("