test: Check that disconnection happens when >4095 garbage bytes is sent

This test type is represented using EXCESS_GARBAGE.

test/functional/p2p_v2_misbehaving.py

@@ -3,12 +3,16 @@
 # 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.p2p import P2PInterface
 from test_framework.test_framework import BitcoinTestFramework
-from test_framework.v2_p2p import EncryptedP2PState
+from test_framework.v2_p2p import (
+    EncryptedP2PState,
+    MAX_GARBAGE_LEN,
+)
 
 
 class TestType(Enum):
@@ -16,8 +20,10 @@ class TestType(Enum):
 
     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
     """
     EARLY_KEY_RESPONSE = 0
+    EXCESS_GARBAGE = 1
 
 
 class EarlyKeyResponseState(EncryptedP2PState):
@@ -32,6 +38,13 @@ class EarlyKeyResponseState(EncryptedP2PState):
         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 MisbehavingV2Peer(P2PInterface):
     """Custom implementation of P2PInterface which uses modified v2 P2P protocol functions for testing purposes."""
     def __init__(self, test_type):
@@ -41,6 +54,8 @@ class MisbehavingV2Peer(P2PInterface):
     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')
         super().connection_made(transport)
 
     def data_received(self, t):
@@ -58,6 +73,7 @@ class EncryptedP2PMisbehaving(BitcoinTestFramework):
 
     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')
@@ -75,6 +91,21 @@ class EncryptedP2PMisbehaving(BitcoinTestFramework):
             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
+        ]
+        for test_type in TestType:
+            if test_type == TestType.EARLY_KEY_RESPONSE:
+                continue
+            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/v2_p2p.py

@@ -109,9 +109,10 @@ class EncryptedP2PState:
             # Responding, place their public key encoding first.
             return TaggedHash("bip324_ellswift_xonly_ecdh", ellswift_theirs + ellswift_ours + ecdh_point_x32)
 
-    def generate_keypair_and_garbage(self):
+    def generate_keypair_and_garbage(self, garbage_len=None):
         """Generates ellswift keypair and 4095 bytes garbage at max"""
         self.privkey_ours, self.ellswift_ours = ellswift_create()
+        if garbage_len is None:
             garbage_len = random.randrange(MAX_GARBAGE_LEN + 1)
         self.sent_garbage = random.randbytes(garbage_len)
         return self.ellswift_ours + self.sent_garbage