merge bitcoin#29431: disconnection scenarios during v2 handshake

src/net.cpp

@@ -2401,7 +2401,11 @@ bool CConnman::InactivityCheck(const CNode& node) const
     }
 
     if (!node.fSuccessfullyConnected) {
-        LogPrint(BCLog::NET, "version handshake timeout peer=%d\n", node.GetId());
+        if (node.m_transport->GetInfo().transport_type == TransportProtocolType::DETECTING) {
+            LogPrint(BCLog::NET, "V2 handshake timeout peer=%d\n", node.GetId());
+        } else {
+            LogPrint(BCLog::NET, "version handshake timeout peer=%d\n", node.GetId());
+        }
         return true;
     }
 

test/functional/p2p_v2_misbehaving.py

@@ -0,0 +1,178 @@
+#!/usr/bin/env python3
+# Copyright (c) 2022 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+import random
+from enum import Enum
+
+from test_framework.messages import MAGIC_BYTES
+from test_framework.util import random_bytes
+from test_framework.p2p import P2PInterface
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import random_bitflip
+from test_framework.v2_p2p import (
+    EncryptedP2PState,
+    MAX_GARBAGE_LEN,
+)
+
+
+class TestType(Enum):
+    """ Scenarios to be tested:
+
+    1. EARLY_KEY_RESPONSE - The responder needs to wait until one byte is received which does not match the 16 bytes
+    consisting of network magic followed by "version\x00\x00\x00\x00\x00" before sending out its ellswift + garbage bytes
+    2. EXCESS_GARBAGE - Disconnection happens when > MAX_GARBAGE_LEN bytes garbage is sent
+    3. WRONG_GARBAGE_TERMINATOR - Disconnection happens when incorrect garbage terminator is sent
+    4. WRONG_GARBAGE - Disconnection happens when garbage bytes that is sent is different from what the peer receives
+    5. SEND_NO_AAD - Disconnection happens when AAD of first encrypted packet after the garbage terminator is not filled
+    6. SEND_NON_EMPTY_VERSION_PACKET - non-empty version packet is simply ignored
+    """
+    EARLY_KEY_RESPONSE = 0
+    EXCESS_GARBAGE = 1
+    WRONG_GARBAGE_TERMINATOR = 2
+    WRONG_GARBAGE = 3
+    SEND_NO_AAD = 4
+    SEND_NON_EMPTY_VERSION_PACKET = 5
+
+
+class EarlyKeyResponseState(EncryptedP2PState):
+    """ Modify v2 P2P protocol functions for testing EARLY_KEY_RESPONSE scenario"""
+    def __init__(self, initiating, net):
+        super().__init__(initiating=initiating, net=net)
+        self.can_data_be_received = False  # variable used to assert if data is received on recvbuf.
+
+    def initiate_v2_handshake(self):
+        """Send ellswift and garbage bytes in 2 parts when TestType = (EARLY_KEY_RESPONSE)"""
+        self.generate_keypair_and_garbage()
+        return b""
+
+
+class ExcessGarbageState(EncryptedP2PState):
+    """Generate > MAX_GARBAGE_LEN garbage bytes"""
+    def generate_keypair_and_garbage(self):
+        garbage_len = MAX_GARBAGE_LEN + random.randrange(1, MAX_GARBAGE_LEN + 1)
+        return super().generate_keypair_and_garbage(garbage_len)
+
+
+class WrongGarbageTerminatorState(EncryptedP2PState):
+    """Add option for sending wrong garbage terminator"""
+    def generate_keypair_and_garbage(self):
+        garbage_len = random.randrange(MAX_GARBAGE_LEN//2)
+        return super().generate_keypair_and_garbage(garbage_len)
+
+    def complete_handshake(self, response):
+        length, handshake_bytes = super().complete_handshake(response)
+        # first 16 bytes returned by complete_handshake() is the garbage terminator
+        wrong_garbage_terminator = random_bitflip(handshake_bytes[:16])
+        return length, wrong_garbage_terminator + handshake_bytes[16:]
+
+
+class WrongGarbageState(EncryptedP2PState):
+    """Generate tampered garbage bytes"""
+    def generate_keypair_and_garbage(self):
+        garbage_len = random.randrange(1, MAX_GARBAGE_LEN)
+        ellswift_garbage_bytes = super().generate_keypair_and_garbage(garbage_len)
+        # assume that garbage bytes sent to TestNode were tampered with
+        return ellswift_garbage_bytes[:64] + random_bitflip(ellswift_garbage_bytes[64:])
+
+
+class NoAADState(EncryptedP2PState):
+    """Add option for not filling first encrypted packet after garbage terminator with AAD"""
+    def generate_keypair_and_garbage(self):
+        garbage_len = random.randrange(1, MAX_GARBAGE_LEN)
+        return super().generate_keypair_and_garbage(garbage_len)
+
+    def complete_handshake(self, response):
+        self.sent_garbage = b''  # do not authenticate the garbage which is sent
+        return super().complete_handshake(response)
+
+
+class NonEmptyVersionPacketState(EncryptedP2PState):
+    """"Add option for sending non-empty transport version packet."""
+    def complete_handshake(self, response):
+        self.transport_version = random_bytes(5)
+        return super().complete_handshake(response)
+
+
+class MisbehavingV2Peer(P2PInterface):
+    """Custom implementation of P2PInterface which uses modified v2 P2P protocol functions for testing purposes."""
+    def __init__(self, test_type):
+        super().__init__()
+        self.test_type = test_type
+
+    def connection_made(self, transport):
+        if self.test_type == TestType.EARLY_KEY_RESPONSE:
+            self.v2_state = EarlyKeyResponseState(initiating=True, net='regtest')
+        elif self.test_type == TestType.EXCESS_GARBAGE:
+            self.v2_state = ExcessGarbageState(initiating=True, net='regtest')
+        elif self.test_type == TestType.WRONG_GARBAGE_TERMINATOR:
+            self.v2_state = WrongGarbageTerminatorState(initiating=True, net='regtest')
+        elif self.test_type == TestType.WRONG_GARBAGE:
+            self.v2_state = WrongGarbageState(initiating=True, net='regtest')
+        elif self.test_type == TestType.SEND_NO_AAD:
+            self.v2_state = NoAADState(initiating=True, net='regtest')
+        elif TestType.SEND_NON_EMPTY_VERSION_PACKET:
+            self.v2_state = NonEmptyVersionPacketState(initiating=True, net='regtest')
+        super().connection_made(transport)
+
+    def data_received(self, t):
+        if self.test_type == TestType.EARLY_KEY_RESPONSE:
+            # check that data can be received on recvbuf only when mismatch from V1_PREFIX happens
+            assert self.v2_state.can_data_be_received
+        else:
+            super().data_received(t)
+
+
+class EncryptedP2PMisbehaving(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+        self.disable_mocktime = True
+        self.extra_args = [["-v2transport=1", "-peertimeout=3"]]
+
+    def run_test(self):
+        self.test_earlykeyresponse()
+        self.test_v2disconnection()
+
+    def test_earlykeyresponse(self):
+        self.log.info('Sending ellswift bytes in parts to ensure that response from responder is received only when')
+        self.log.info('ellswift bytes have a mismatch from the 16 bytes(network magic followed by "version\\x00\\x00\\x00\\x00\\x00")')
+        node0 = self.nodes[0]
+        self.log.info('Sending first 4 bytes of ellswift which match network magic')
+        self.log.info('If a response is received, assertion failure would happen in our custom data_received() function')
+        peer1 = node0.add_p2p_connection(MisbehavingV2Peer(TestType.EARLY_KEY_RESPONSE), wait_for_verack=False, send_version=False, supports_v2_p2p=True, wait_for_v2_handshake=False)
+        peer1.send_raw_message(MAGIC_BYTES['regtest'])
+        self.log.info('Sending remaining ellswift and garbage which are different from V1_PREFIX. Since a response is')
+        self.log.info('expected now, our custom data_received() function wouldn\'t result in assertion failure')
+        peer1.v2_state.can_data_be_received = True
+        peer1.send_raw_message(peer1.v2_state.ellswift_ours[4:] + peer1.v2_state.sent_garbage)
+        with node0.assert_debug_log(['V2 handshake timeout peer=0']):
+            peer1.wait_for_disconnect(timeout=5)
+        self.log.info('successful disconnection since modified ellswift was sent as response')
+
+    def test_v2disconnection(self):
+        # test v2 disconnection scenarios
+        node0 = self.nodes[0]
+        expected_debug_message = [
+            [],  # EARLY_KEY_RESPONSE
+            ["V2 transport error: missing garbage terminator, peer=1"],  # EXCESS_GARBAGE
+            ["V2 handshake timeout peer=2"],  # WRONG_GARBAGE_TERMINATOR
+            ["V2 transport error: packet decryption failure"],  # WRONG_GARBAGE
+            ["V2 transport error: packet decryption failure"],  # SEND_NO_AAD
+            [],  # SEND_NON_EMPTY_VERSION_PACKET
+        ]
+        for test_type in TestType:
+            if test_type == TestType.EARLY_KEY_RESPONSE:
+                continue
+            elif test_type == TestType.SEND_NON_EMPTY_VERSION_PACKET:
+                node0.add_p2p_connection(MisbehavingV2Peer(test_type), wait_for_verack=True, send_version=True, supports_v2_p2p=True)
+                self.log.info(f"No disconnection for {test_type.name}")
+            else:
+                with node0.assert_debug_log(expected_debug_message[test_type.value], timeout=5):
+                    peer = node0.add_p2p_connection(MisbehavingV2Peer(test_type), wait_for_verack=False, send_version=False, supports_v2_p2p=True, expect_success=False)
+                    peer.wait_for_disconnect()
+                self.log.info(f"Expected disconnection for {test_type.name}")
+
+
+if __name__ == '__main__':
+    EncryptedP2PMisbehaving().main()

test/functional/test_framework/key.py

@@ -14,6 +14,7 @@
 import unittest
 
 from test_framework.crypto import secp256k1
+from test_framework.util import random_bitflip
 
 # Order of the secp256k1 curve
 ORDER = secp256k1.GE.ORDER
@@ -289,11 +290,6 @@ def sign_schnorr(key, msg, aux=None, flip_p=False, flip_r=False):
 class TestFrameworkKey(unittest.TestCase):
     def test_ecdsa_and_schnorr(self):
         """Test the Python ECDSA and Schnorr implementations."""
-        def random_bitflip(sig):
-            sig = list(sig)
-            sig[random.randrange(len(sig))] ^= (1 << (random.randrange(8)))
-            return bytes(sig)
-
         byte_arrays = [generate_privkey() for _ in range(3)] + [v.to_bytes(32, 'big') for v in [0, ORDER - 1, ORDER, 2**256 - 1]]
         keys = {}
         for privkey_bytes in byte_arrays:  # build array of key/pubkey pairs

test/functional/test_framework/p2p.py

@@ -249,6 +249,7 @@ def connection_made(self, transport):
         # send the initial handshake immediately
         if self.supports_v2_p2p and self.v2_state.initiating and not self.v2_state.tried_v2_handshake:
             send_handshake_bytes = self.v2_state.initiate_v2_handshake()
+            logger.debug(f"sending {len(self.v2_state.sent_garbage)} bytes of garbage data")
             self.send_raw_message(send_handshake_bytes)
         # if v2 connection, send `on_connection_send_msg` after initial v2 handshake.
         # if reconnection situation, send `on_connection_send_msg` after version message is received in `on_version()`.
@@ -289,6 +290,7 @@ def v2_handshake(self):
                     self.v2_state = None
                     return
                 elif send_handshake_bytes:
+                    logger.debug(f"sending {len(self.v2_state.sent_garbage)} bytes of garbage data")
                     self.send_raw_message(send_handshake_bytes)
                 elif send_handshake_bytes == b"":
                     return  # only after send_handshake_bytes are sent can `complete_handshake()` be done

test/functional/test_framework/test_node.py

@@ -632,7 +632,7 @@ def assert_start_raises_init_error(self, extra_args=None, expected_msg=None, mat
                     assert_msg += "with expected error " + expected_msg
                 self._raise_assertion_error(assert_msg)
 
-    def add_p2p_connection(self, p2p_conn, *, wait_for_verack=True, send_version=True, supports_v2_p2p=None, wait_for_v2_handshake=True, **kwargs):
+    def add_p2p_connection(self, p2p_conn, *, wait_for_verack=True, send_version=True, supports_v2_p2p=None, wait_for_v2_handshake=True, expect_success=True, **kwargs):
         """Add an inbound p2p connection to the node.
 
         This method adds the p2p connection to the self.p2ps list and also
@@ -652,14 +652,15 @@ def add_p2p_connection(self, p2p_conn, *, wait_for_verack=True, send_version=Tru
         if supports_v2_p2p is None:
             supports_v2_p2p = self.use_v2transport
 
-
         p2p_conn.p2p_connected_to_node = True
         if self.use_v2transport:
             kwargs['services'] = kwargs.get('services', P2P_SERVICES) | NODE_P2P_V2
         supports_v2_p2p = self.use_v2transport and supports_v2_p2p
         p2p_conn.peer_connect(**kwargs, send_version=send_version, net=self.chain, timeout_factor=self.timeout_factor, supports_v2_p2p=supports_v2_p2p)()
 
         self.p2ps.append(p2p_conn)
+        if not expect_success:
+            return p2p_conn
         p2p_conn.wait_until(lambda: p2p_conn.is_connected, check_connected=False)
         if supports_v2_p2p and wait_for_v2_handshake:
             p2p_conn.wait_until(lambda: p2p_conn.v2_state.tried_v2_handshake)

test/functional/test_framework/util.py

@@ -219,6 +219,12 @@ def str_to_b64str(string):
     return b64encode(string.encode('utf-8')).decode('ascii')
 
 
+def random_bitflip(data):
+    data = list(data)
+    data[random.randrange(len(data))] ^= (1 << (random.randrange(8)))
+    return bytes(data)
+
+
 def satoshi_round(amount):
     return Decimal(amount).quantize(Decimal('0.00000001'), rounding=ROUND_DOWN)