test: Introduce test types and modify v2 handshake function accordingly

Prior to this commit, TestEncryptedP2PState would always
send initial_v2_handshake bytes in 2 parts (as required
by early key response test).

For generalising this test and having different v2 handshake
behaviour based on the test type, special behaviours like
sending initial_v2_handshake bytes in 2 parts are executed
only if test_type is set to EARLY_KEY_RESPONSE.

test/functional/p2p_v2_misbehaving.py

@@ -3,87 +3,78 @@
 # 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.test_framework import BitcoinTestFramework
-from test_framework.crypto.ellswift import ellswift_create
+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
 
 
-class TestEncryptedP2PState(EncryptedP2PState):
-    """ Modify v2 P2P protocol functions for testing that "The responder waits until one byte is received which does
-    not match the 16 bytes consisting of the network magic followed by "version\x00\x00\x00\x00\x00"." (see BIP 324)
+class TestType(Enum):
+    """ Scenarios to be tested:
 
-    - if `send_net_magic` is True, send first 4 bytes of ellswift (match network magic) else send remaining 60 bytes
-    - `can_data_be_received` is a variable used to assert if data is received on recvbuf.
-            - v2 TestNode shouldn't respond back if we send V1_PREFIX and data shouldn't be received on recvbuf.
-              This state is represented using `can_data_be_received` = False.
-            - v2 TestNode responds back when mismatch from V1_PREFIX happens and data can be received on recvbuf.
-              This state is represented using `can_data_be_received` = True.
+    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
     """
+    EARLY_KEY_RESPONSE = 0
 
-    def __init__(self):
-        super().__init__(initiating=True, net='regtest')
-        self.send_net_magic = True
-        self.can_data_be_received = False
-
-    def initiate_v2_handshake(self, garbage_len=random.randrange(4096)):
-        """Initiator begins the v2 handshake by sending its ellswift bytes and garbage.
-        Here, the 64 bytes ellswift is assumed to have it's 4 bytes match network magic bytes. It is sent in 2 phases:
-            1. when `send_network_magic` = True, send first 4 bytes of ellswift (matches network magic bytes)
-            2. when `send_network_magic` = False, send remaining 60 bytes of ellswift
-        """
-        if self.send_net_magic:
-            self.privkey_ours, self.ellswift_ours = ellswift_create()
-            self.sent_garbage = random.randbytes(garbage_len)
-            self.send_net_magic = False
-            return b"\xfa\xbf\xb5\xda"
-        else:
-            self.can_data_be_received = True
-            return self.ellswift_ours[4:] + self.sent_garbage
 
+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 PeerEarlyKey(P2PInterface):
+
+class MisbehavingV2Peer(P2PInterface):
     """Custom implementation of P2PInterface which uses modified v2 P2P protocol functions for testing purposes."""
-    def __init__(self):
+    def __init__(self, test_type):
         super().__init__()
-        self.v2_state = None
-        self.connection_opened = False
+        self.test_type = test_type
 
     def connection_made(self, transport):
-        """64 bytes ellswift is sent in 2 parts during `initial_v2_handshake()`"""
-        self.v2_state = TestEncryptedP2PState()
+        if self.test_type == TestType.EARLY_KEY_RESPONSE:
+            self.v2_state = EarlyKeyResponseState(initiating=True, net='regtest')
         super().connection_made(transport)
 
     def data_received(self, t):
-        # check that data can be received on recvbuf only when mismatch from V1_PREFIX happens (send_net_magic = False)
-        assert self.v2_state.can_data_be_received and not self.v2_state.send_net_magic
+        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)
 
-    def on_open(self):
-        self.connection_opened = True
 
-class P2PEarlyKey(BitcoinTestFramework):
+class EncryptedP2PMisbehaving(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 1
         self.extra_args = [["-v2transport=1", "-peertimeout=3"]]
 
     def run_test(self):
+        self.test_earlykeyresponse()
+
+    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')
-        # send happens in `initiate_v2_handshake()` in `connection_made()`
-        peer1 = node0.add_p2p_connection(PeerEarlyKey(), wait_for_verack=False, send_version=False, supports_v2_p2p=True, wait_for_v2_handshake=False)
-        self.wait_until(lambda: peer1.connection_opened)
+        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')
-        ellswift_and_garbage_data = peer1.v2_state.initiate_v2_handshake()
-        peer1.send_raw_message(ellswift_and_garbage_data)
-        peer1.wait_for_disconnect(timeout=5)
-        self.log.info('successful disconnection when MITM happens in the key exchange phase')
+        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')
 
 
 if __name__ == '__main__':
-    P2PEarlyKey().main()
+    EncryptedP2PMisbehaving().main()