diff --git a/test/functional/abc-invalid-message.py b/test/functional/abc-invalid-message.py
index b820c6db1..f1a40b109 100755
--- a/test/functional/abc-invalid-message.py
+++ b/test/functional/abc-invalid-message.py
@@ -1,103 +1,103 @@
 #!/usr/bin/env python3
 # Copyright (c) 2019 The Bitcoin developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """ABC Invalid Message Test
 
 Test that invalid messages get rejected and/or ban the sender as expected for
 each case.
 """
 
 import struct
 
 from test_framework.messages import NODE_NETWORK, msg_version
 from test_framework.mininode import (
     MAGIC_BYTES,
     mininode_lock,
     msg_ping,
     P2PInterface,
 )
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import wait_until
 
 
 def msg_bad_checksum(connection, original_message):
-    message_data = bytearray(connection._build_message(original_message))
+    message_data = bytearray(connection.build_message(original_message))
 
     data = original_message.serialize()
     i = 0
     i += len(MAGIC_BYTES[connection.network])
     i += 12
     i += len(struct.pack("<I", len(data)))
 
     # Make the checksum invalid
     message_data[i] = message_data[i] ^ 0xAA
     return message_data
 
 
 class BadVersionP2PInterface(P2PInterface):
     def peer_connect(self, *args, services=NODE_NETWORK,
                      send_version=False, **kwargs):
         create_conn = super().peer_connect(*args, send_version=send_version, **kwargs)
 
         # Send version message with invalid checksum
         vt = msg_version()
         vt.nServices = services
         vt.addrTo.ip = self.dstaddr
         vt.addrTo.port = self.dstport
         vt.addrFrom.ip = "0.0.0.0"
         vt.addrFrom.port = 0
         invalid_vt = msg_bad_checksum(self, vt)
         # Will be sent right after connection_made
         self.on_connection_send_msg = invalid_vt
         self.on_connection_send_msg_is_raw = True
 
         return create_conn
 
 
 class InvalidMessageTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = False
         self.num_nodes = 2
 
     def run_test(self):
         # Try to connect to a node using an invalid checksum on version message
         bad_interface = BadVersionP2PInterface()
         self.nodes[0].add_p2p_connection(
             bad_interface, send_version=False, wait_for_verack=False)
 
         # Also connect to a node with a valid version message
         interface = P2PInterface()
         # Node with valid version message should connect successfully
         connection = self.nodes[1].add_p2p_connection(interface)
 
         # The invalid version message should cause a disconnect on the first
         # connection because we are now banned
         bad_interface.wait_for_disconnect()
 
         # Create a valid message
         valid_message = msg_ping(interface.ping_counter)
 
         def wait_for_ping():
             def check_ping():
                 if not interface.last_message.get("pong"):
                     return False
                 return interface.last_message["pong"].nonce == interface.ping_counter
             wait_until(check_ping, lock=mininode_lock)
             interface.ping_counter += 1
 
         # The valid message is accepted
         connection.send_message(valid_message)
         wait_for_ping()
 
         # Make an invalid copy of the valid message with an invalid checksum
         invalid_message = msg_bad_checksum(connection, valid_message)
 
         # The invalid message should cause a disconnect because we are now
         # banned
         connection.send_raw_message(invalid_message)
         interface.wait_for_disconnect()
 
 
 if __name__ == '__main__':
     InvalidMessageTest().main()
diff --git a/test/functional/p2p_invalid_messages.py b/test/functional/p2p_invalid_messages.py
new file mode 100755
index 000000000..001a641bf
--- /dev/null
+++ b/test/functional/p2p_invalid_messages.py
@@ -0,0 +1,180 @@
+#!/usr/bin/env python3
+# Copyright (c) 2015-2018 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
+
+from test_framework import messages
+from test_framework.mininode import P2PDataStore
+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 msg_nametoolong(msg_unrecognized):
+
+    command = b'thisnameiswayyyyyyyyytoolong'
+
+
+class InvalidMessagesTest(BitcoinTestFramework):
+
+    def set_test_params(self):
+        self.num_nodes = 1
+        self.setup_clean_chain = True
+
+    def run_test(self):
+        """
+        0. Send a bunch of large (2MB) messages of an unrecognized type. Check to see
+           that it isn't an effective DoS against the node.
+
+        1. Send an oversized (2MB+) 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.
+
+        3. Send an unrecognized message with a command name longer than 12 characters.
+
+        """
+        node = self.nodes[0]
+        self.node = node
+        node.add_p2p_connection(P2PDataStore())
+        conn2 = node.add_p2p_connection(P2PDataStore())
+
+        # 2MB, per MAX_PROTOCOL_MESSAGE_LENGTH
+        msg_limit = 2 * 1024 * 1024
+        # Account for the 4-byte length prefix
+        valid_data_limit = msg_limit - 5
+
+        #
+        # 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("b" * valid_data_limit)
+        assert len(msg_at_size.serialize()) == msg_limit
+
+        with node.assert_memory_usage_stable(perc_increase_allowed=0.03):
+            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=30)
+            assert node.p2p.is_connected
+
+        #
+        # 1.
+        #
+        # Send an oversized message, ensure we're disconnected.
+        #
+        msg_over_size = msg_unrecognized("b" * (valid_data_limit + 1))
+        assert len(msg_over_size.serialize()) == (msg_limit + 1)
+
+        with node.assert_debug_log(["Oversized header detected"]):
+            # 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()
+
+        #
+        # 2.
+        #
+        # Send messages with an incorrect data size in the header.
+        #
+        actual_size = 100
+        msg = msg_unrecognized("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())
+
+        #
+        # 3.
+        #
+        # Send a message with a too-long command name.
+        #
+        node.p2p.send_message(msg_nametoolong("foobar"))
+        node.p2p.wait_for_disconnect(timeout=4)
+
+        # Node is still up.
+        conn = node.add_p2p_connection(P2PDataStore())
+        conn.sync_with_ping()
+
+    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()
diff --git a/test/functional/test_framework/mininode.py b/test/functional/test_framework/mininode.py
index 3ebb2ffb1..ffe74bb0c 100755
--- a/test/functional/test_framework/mininode.py
+++ b/test/functional/test_framework/mininode.py
@@ -1,663 +1,663 @@
 #!/usr/bin/env python3
 # Copyright (c) 2010 ArtForz -- public domain half-a-node
 # Copyright (c) 2012 Jeff Garzik
 # Copyright (c) 2010-2019 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Bitcoin P2P network half-a-node.
 
 This python code was modified from ArtForz' public domain half-a-node, as
 found in the mini-node branch of http://github.com/jgarzik/pynode.
 
 P2PConnection: A low-level connection object to a node's P2P interface
 P2PInterface: A high-level interface object for communicating to a node over P2P
 P2PDataStore: A p2p interface class that keeps a store of transactions and blocks
               and can respond correctly to getdata and getheaders messages"""
 import asyncio
 from collections import defaultdict
 from io import BytesIO
 import logging
 import struct
 import sys
 import threading
 
 from test_framework.messages import (
     CBlockHeader,
     MIN_VERSION_SUPPORTED,
     msg_addr,
     msg_avapoll,
     msg_tcpavaresponse,
     msg_block,
     MSG_BLOCK,
     msg_blocktxn,
     msg_cmpctblock,
     msg_feefilter,
     msg_getaddr,
     msg_getblocks,
     msg_getblocktxn,
     msg_getdata,
     msg_getheaders,
     msg_headers,
     msg_inv,
     msg_mempool,
     msg_notfound,
     msg_ping,
     msg_pong,
     msg_reject,
     msg_sendcmpct,
     msg_sendheaders,
     msg_tx,
     MSG_TX,
     MSG_TYPE_MASK,
     msg_verack,
     msg_version,
     NODE_NETWORK,
     sha256,
 )
 from test_framework.util import wait_until
 
 logger = logging.getLogger("TestFramework.mininode")
 
 MESSAGEMAP = {
     b"addr": msg_addr,
     b"avapoll": msg_avapoll,
     b"avaresponse": msg_tcpavaresponse,
     b"block": msg_block,
     b"blocktxn": msg_blocktxn,
     b"cmpctblock": msg_cmpctblock,
     b"feefilter": msg_feefilter,
     b"getaddr": msg_getaddr,
     b"getblocks": msg_getblocks,
     b"getblocktxn": msg_getblocktxn,
     b"getdata": msg_getdata,
     b"getheaders": msg_getheaders,
     b"headers": msg_headers,
     b"inv": msg_inv,
     b"mempool": msg_mempool,
     b"notfound": msg_notfound,
     b"ping": msg_ping,
     b"pong": msg_pong,
     b"reject": msg_reject,
     b"sendcmpct": msg_sendcmpct,
     b"sendheaders": msg_sendheaders,
     b"tx": msg_tx,
     b"verack": msg_verack,
     b"version": msg_version,
 }
 
 MAGIC_BYTES = {
     "mainnet": b"\xe3\xe1\xf3\xe8",
     "testnet3": b"\xf4\xe5\xf3\xf4",
     "regtest": b"\xda\xb5\xbf\xfa",
 }
 
 
 class P2PConnection(asyncio.Protocol):
     """A low-level connection object to a node's P2P interface.
 
     This class is responsible for:
 
     - opening and closing the TCP connection to the node
     - reading bytes from and writing bytes to the socket
     - deserializing and serializing the P2P message header
     - logging messages as they are sent and received
 
     This class contains no logic for handing the P2P message payloads. It must be
     sub-classed and the on_message() callback overridden."""
 
     def __init__(self):
         # The underlying transport of the connection.
         # Should only call methods on this from the NetworkThread, c.f.
         # call_soon_threadsafe
         self._transport = None
 
     @property
     def is_connected(self):
         return self._transport is not None
 
     def peer_connect(self, dstaddr, dstport, net="regtest"):
         assert not self.is_connected
         self.dstaddr = dstaddr
         self.dstport = dstport
         # The initial message to send after the connection was made:
         self.on_connection_send_msg = None
         self.on_connection_send_msg_is_raw = False
         self.recvbuf = b""
         self.network = net
         logger.debug('Connecting to Bitcoin Node: {}:{}'.format(
             self.dstaddr, self.dstport))
 
         loop = NetworkThread.network_event_loop
         conn_gen_unsafe = loop.create_connection(
             lambda: self, host=self.dstaddr, port=self.dstport)
 
         def conn_gen(): return loop.call_soon_threadsafe(
             loop.create_task, conn_gen_unsafe)
         return conn_gen
 
     def peer_disconnect(self):
         # Connection could have already been closed by other end.
         NetworkThread.network_event_loop.call_soon_threadsafe(
             lambda: self._transport and self._transport.abort())
 
     # Connection and disconnection methods
 
     def connection_made(self, transport):
         """asyncio callback when a connection is opened."""
         assert not self._transport
         logger.debug("Connected & Listening: {}:{}".format(
             self.dstaddr, self.dstport))
         self._transport = transport
         if self.on_connection_send_msg:
             if self.on_connection_send_msg_is_raw:
                 self.send_raw_message(self.on_connection_send_msg)
             else:
                 self.send_message(self.on_connection_send_msg)
             # Never used again
             self.on_connection_send_msg = None
         self.on_open()
 
     def connection_lost(self, exc):
         """asyncio callback when a connection is closed."""
         if exc:
             logger.warning("Connection lost to {}:{} due to {}".format(
                 self.dstaddr, self.dstport, exc))
         else:
             logger.debug("Closed connection to: {}:{}".format(
                 self.dstaddr, self.dstport))
         self._transport = None
         self.recvbuf = b""
         self.on_close()
 
     # Socket read methods
 
     def data_received(self, t):
         """asyncio callback when data is read from the socket."""
         with mininode_lock:
             if len(t) > 0:
                 self.recvbuf += t
 
         while True:
             msg = self._on_data()
             if msg is None:
                 break
             self.on_message(msg)
 
     def _on_data(self):
         """Try to read P2P messages from the recv buffer.
 
         This method reads data from the buffer in a loop. It deserializes,
         parses and verifies the P2P header, then passes the P2P payload to
         the on_message callback for processing."""
         try:
             with mininode_lock:
                 if len(self.recvbuf) < 4:
                     return None
                 if self.recvbuf[:4] != MAGIC_BYTES[self.network]:
                     raise ValueError(
                         "got garbage {}".format(repr(self.recvbuf)))
                 if len(self.recvbuf) < 4 + 12 + 4 + 4:
                     return None
                 command = self.recvbuf[4:4 + 12].split(b"\x00", 1)[0]
                 msglen = struct.unpack(
                     "<i", self.recvbuf[4 + 12:4 + 12 + 4])[0]
                 checksum = self.recvbuf[4 + 12 + 4:4 + 12 + 4 + 4]
                 if len(self.recvbuf) < 4 + 12 + 4 + 4 + msglen:
                     return None
                 msg = self.recvbuf[4 + 12 + 4 + 4:4 + 12 + 4 + 4 + msglen]
                 h = sha256(sha256(msg))
                 if checksum != h[:4]:
                     raise ValueError("got bad checksum " + repr(self.recvbuf))
                 self.recvbuf = self.recvbuf[4 + 12 + 4 + 4 + msglen:]
                 if command not in MESSAGEMAP:
                     raise ValueError("Received unknown command from {}:{}: '{}' {}".format(
                         self.dstaddr, self.dstport, command, repr(msg)))
                 f = BytesIO(msg)
                 m = MESSAGEMAP[command]()
                 m.deserialize(f)
                 self._log_message("receive", m)
                 return m
         except Exception as e:
             logger.exception('Error reading message:', repr(e))
             raise
 
     def on_message(self, message):
         """Callback for processing a P2P payload. Must be overridden by derived class."""
         raise NotImplementedError
 
     # Socket write methods
 
     def send_message(self, message):
         """Send a P2P message over the socket.
 
         This method takes a P2P payload, builds the P2P header and adds
         the message to the send buffer to be sent over the socket."""
         if not self.is_connected:
             raise IOError('Not connected')
+        tmsg = self.build_message(message)
         self._log_message("send", message)
-        tmsg = self._build_message(message)
-        self.send_raw_message(tmsg)
+        return self.send_raw_message(tmsg)
 
-    def send_raw_message(self, tmsg):
+    def send_raw_message(self, raw_message_bytes):
         """Send any raw message over the socket.
 
         This method adds a raw message to the send buffer to be sent over the
         socket."""
         if not self.is_connected:
             raise IOError('Not connected')
 
         def maybe_write():
             if not self._transport:
                 return
             if self._transport.is_closing():
                 return
-            self._transport.write(tmsg)
+            self._transport.write(raw_message_bytes)
         NetworkThread.network_event_loop.call_soon_threadsafe(maybe_write)
 
     # Class utility methods
 
-    def _build_message(self, message):
+    def build_message(self, message):
         """Build a serialized P2P message"""
         command = message.command
         data = message.serialize()
         tmsg = MAGIC_BYTES[self.network]
         tmsg += command
         tmsg += b"\x00" * (12 - len(command))
         tmsg += struct.pack("<I", len(data))
         th = sha256(data)
         h = sha256(th)
         tmsg += h[:4]
         tmsg += data
         return tmsg
 
     def _log_message(self, direction, msg):
         """Logs a message being sent or received over the connection."""
         if direction == "send":
             log_message = "Send message to "
         elif direction == "receive":
             log_message = "Received message from "
         log_message += "{}:{}: {}".format(
             self.dstaddr, self.dstport, repr(msg)[:500])
         if len(log_message) > 500:
             log_message += "... (msg truncated)"
         logger.debug(log_message)
 
 
 class P2PInterface(P2PConnection):
     """A high-level P2P interface class for communicating with a Bitcoin Cash node.
 
     This class provides high-level callbacks for processing P2P message
     payloads, as well as convenience methods for interacting with the
     node over P2P.
 
     Individual testcases should subclass this and override the on_* methods
     if they want to alter message handling behaviour."""
 
     def __init__(self):
         super().__init__()
 
         # Track number of messages of each type received and the most recent
         # message of each type
         self.message_count = defaultdict(int)
         self.last_message = {}
 
         # A count of the number of ping messages we've sent to the node
         self.ping_counter = 1
 
         # The network services received from the peer
         self.nServices = 0
 
     def peer_connect(self, *args, services=NODE_NETWORK,
                      send_version=True, **kwargs):
         create_conn = super().peer_connect(*args, **kwargs)
 
         if send_version:
             # Send a version msg
             vt = msg_version()
             vt.nServices = services
             vt.addrTo.ip = self.dstaddr
             vt.addrTo.port = self.dstport
             vt.addrFrom.ip = "0.0.0.0"
             vt.addrFrom.port = 0
             # Will be sent soon after connection_made
             self.on_connection_send_msg = vt
 
         return create_conn
 
     # Message receiving methods
 
     def on_message(self, message):
         """Receive message and dispatch message to appropriate callback.
 
         We keep a count of how many of each message type has been received
         and the most recent message of each type."""
         with mininode_lock:
             try:
                 command = message.command.decode('ascii')
                 self.message_count[command] += 1
                 self.last_message[command] = message
                 getattr(self, 'on_' + command)(message)
             except Exception:
                 print("ERROR delivering {} ({})".format(
                     repr(message), sys.exc_info()[0]))
                 raise
 
     # Callback methods. Can be overridden by subclasses in individual test
     # cases to provide custom message handling behaviour.
 
     def on_open(self):
         pass
 
     def on_close(self):
         pass
 
     def on_addr(self, message): pass
 
     def on_avapoll(self, message): pass
 
     def on_avaresponse(self, message): pass
 
     def on_block(self, message): pass
 
     def on_blocktxn(self, message): pass
 
     def on_cmpctblock(self, message): pass
 
     def on_feefilter(self, message): pass
 
     def on_getaddr(self, message): pass
 
     def on_getblocks(self, message): pass
 
     def on_getblocktxn(self, message): pass
 
     def on_getdata(self, message): pass
 
     def on_getheaders(self, message): pass
 
     def on_headers(self, message): pass
 
     def on_mempool(self, message): pass
 
     def on_notfound(self, message): pass
 
     def on_pong(self, message): pass
 
     def on_reject(self, message): pass
 
     def on_sendcmpct(self, message): pass
 
     def on_sendheaders(self, message): pass
 
     def on_tx(self, message): pass
 
     def on_inv(self, message):
         want = msg_getdata()
         for i in message.inv:
             if i.type != 0:
                 want.inv.append(i)
         if len(want.inv):
             self.send_message(want)
 
     def on_ping(self, message):
         self.send_message(msg_pong(message.nonce))
 
     def on_verack(self, message):
         self.verack_received = True
 
     def on_version(self, message):
         assert message.nVersion >= MIN_VERSION_SUPPORTED, "Version {} received. Test framework only supports versions greater than {}".format(
             message.nVersion, MIN_VERSION_SUPPORTED)
         self.send_message(msg_verack())
         self.nServices = message.nServices
 
     # Connection helper methods
 
     def wait_for_disconnect(self, timeout=60):
         def test_function(): return not self.is_connected
         wait_until(test_function, timeout=timeout, lock=mininode_lock)
 
     # Message receiving helper methods
 
     def wait_for_block(self, blockhash, timeout=60):
         def test_function(): return self.last_message.get(
             "block") and self.last_message["block"].block.rehash() == blockhash
         wait_until(test_function, timeout=timeout, lock=mininode_lock)
 
     def wait_for_header(self, blockhash, timeout=60):
         def test_function():
             last_headers = self.last_message.get('headers')
             if not last_headers:
                 return False
             return last_headers.headers[0].rehash() == blockhash
 
         wait_until(test_function, timeout=timeout, lock=mininode_lock)
 
     def wait_for_getdata(self, timeout=60):
         """Waits for a getdata message.
 
         Receiving any getdata message will satisfy the predicate. the last_message["getdata"]
         value must be explicitly cleared before calling this method, or this will return
         immediately with success. TODO: change this method to take a hash value and only
         return true if the correct block/tx has been requested."""
         def test_function(): return self.last_message.get("getdata")
         wait_until(test_function, timeout=timeout, lock=mininode_lock)
 
     def wait_for_getheaders(self, timeout=60):
         """Waits for a getheaders message.
 
         Receiving any getheaders message will satisfy the predicate. the last_message["getheaders"]
         value must be explicitly cleared before calling this method, or this will return
         immediately with success. TODO: change this method to take a hash value and only
         return true if the correct block header has been requested."""
         def test_function(): return self.last_message.get("getheaders")
         wait_until(test_function, timeout=timeout, lock=mininode_lock)
 
     def wait_for_inv(self, expected_inv, timeout=60):
         """Waits for an INV message and checks that the first inv object in the message was as expected."""
         if len(expected_inv) > 1:
             raise NotImplementedError(
                 "wait_for_inv() will only verify the first inv object")
 
         def test_function(): return self.last_message.get("inv") and \
             self.last_message["inv"].inv[0].type == expected_inv[0].type and \
             self.last_message["inv"].inv[0].hash == expected_inv[0].hash
         wait_until(test_function, timeout=timeout, lock=mininode_lock)
 
     def wait_for_verack(self, timeout=60):
         def test_function(): return self.message_count["verack"]
         wait_until(test_function, timeout=timeout, lock=mininode_lock)
 
     # Message sending helper functions
 
-    def send_and_ping(self, message):
+    def send_and_ping(self, message, timeout=60):
         self.send_message(message)
-        self.sync_with_ping()
+        self.sync_with_ping(timeout=timeout)
 
     # Sync up with the node
     def sync_with_ping(self, timeout=60):
         self.send_message(msg_ping(nonce=self.ping_counter))
 
         def test_function():
             if not self.last_message.get("pong"):
                 return False
             return self.last_message["pong"].nonce == self.ping_counter
         wait_until(test_function, timeout=timeout, lock=mininode_lock)
         self.ping_counter += 1
 
 
 # One lock for synchronizing all data access between the networking thread (see
 # NetworkThread below) and the thread running the test logic.  For simplicity,
 # P2PConnection acquires this lock whenever delivering a message to a P2PInterface.
 # This lock should be acquired in the thread running the test logic to synchronize
 # access to any data shared with the P2PInterface or P2PConnection.
 mininode_lock = threading.RLock()
 
 
 class NetworkThread(threading.Thread):
     network_event_loop = None
 
     def __init__(self):
         super().__init__(name="NetworkThread")
         # There is only one event loop and no more than one thread must be
         # created
         assert not self.network_event_loop
 
         NetworkThread.network_event_loop = asyncio.new_event_loop()
 
     def run(self):
         """Start the network thread."""
         self.network_event_loop.run_forever()
 
     def close(self, timeout=10):
         """Close the connections and network event loop."""
         self.network_event_loop.call_soon_threadsafe(
             self.network_event_loop.stop)
         wait_until(lambda: not self.network_event_loop.is_running(),
                    timeout=timeout)
         self.network_event_loop.close()
         self.join(timeout)
 
 
 class P2PDataStore(P2PInterface):
     """A P2P data store class.
 
     Keeps a block and transaction store and responds correctly to getdata and getheaders requests."""
 
     def __init__(self):
         super().__init__()
         # store of blocks. key is block hash, value is a CBlock object
         self.block_store = {}
         self.last_block_hash = ''
         # store of txs. key is txid, value is a CTransaction object
         self.tx_store = {}
         self.getdata_requests = []
 
     def on_getdata(self, message):
         """Check for the tx/block in our stores and if found, reply with an inv message."""
         for inv in message.inv:
             self.getdata_requests.append(inv.hash)
             if (inv.type & MSG_TYPE_MASK) == MSG_TX and inv.hash in self.tx_store.keys():
                 self.send_message(msg_tx(self.tx_store[inv.hash]))
             elif (inv.type & MSG_TYPE_MASK) == MSG_BLOCK and inv.hash in self.block_store.keys():
                 self.send_message(msg_block(self.block_store[inv.hash]))
             else:
                 logger.debug(
                     'getdata message type {} received.'.format(hex(inv.type)))
 
     def on_getheaders(self, message):
         """Search back through our block store for the locator, and reply with a headers message if found."""
 
         locator, hash_stop = message.locator, message.hashstop
 
         # Assume that the most recent block added is the tip
         if not self.block_store:
             return
 
         headers_list = [self.block_store[self.last_block_hash]]
         maxheaders = 2000
         while headers_list[-1].sha256 not in locator.vHave:
             # Walk back through the block store, adding headers to headers_list
             # as we go.
             prev_block_hash = headers_list[-1].hashPrevBlock
             if prev_block_hash in self.block_store:
                 prev_block_header = CBlockHeader(
                     self.block_store[prev_block_hash])
                 headers_list.append(prev_block_header)
                 if prev_block_header.sha256 == hash_stop:
                     # if this is the hashstop header, stop here
                     break
             else:
                 logger.debug('block hash {} not found in block store'.format(
                     hex(prev_block_hash)))
                 break
 
         # Truncate the list if there are too many headers
         headers_list = headers_list[:-maxheaders - 1:-1]
         response = msg_headers(headers_list)
 
         if response is not None:
             self.send_message(response)
 
     def send_blocks_and_test(self, blocks, node, *, success=True, request_block=True,
                              reject_reason=None, expect_disconnect=False, timeout=60):
         """Send blocks to test node and test whether the tip advances.
 
          - add all blocks to our block_store
          - send a headers message for the final block
          - the on_getheaders handler will ensure that any getheaders are responded to
          - if request_block is True: wait for getdata for each of the blocks. The on_getdata handler will
            ensure that any getdata messages are responded to
          - if success is True: assert that the node's tip advances to the most recent block
          - if success is False: assert that the node's tip doesn't advance
          - if reject_reason is set: assert that the correct reject message is logged"""
 
         with mininode_lock:
             for block in blocks:
                 self.block_store[block.sha256] = block
                 self.last_block_hash = block.sha256
 
         def test():
             self.send_message(msg_headers([CBlockHeader(blocks[-1])]))
 
             if request_block:
                 wait_until(
                     lambda: blocks[-1].sha256 in self.getdata_requests, timeout=timeout, lock=mininode_lock)
 
             if expect_disconnect:
                 self.wait_for_disconnect(timeout=timeout)
             else:
                 self.sync_with_ping(timeout=timeout)
 
             if success:
                 wait_until(lambda: node.getbestblockhash() ==
                            blocks[-1].hash, timeout=timeout)
             else:
                 assert node.getbestblockhash() != blocks[-1].hash
 
         if reject_reason:
             with node.assert_debug_log(expected_msgs=[reject_reason]):
                 test()
         else:
             test()
 
     def send_txs_and_test(self, txs, node, *, success=True,
                           expect_disconnect=False, reject_reason=None):
         """Send txs to test node and test whether they're accepted to the mempool.
 
          - add all txs to our tx_store
          - send tx messages for all txs
          - if success is True/False: assert that the txs are/are not accepted to the mempool
          - if expect_disconnect is True: Skip the sync with ping
          - if reject_reason is set: assert that the correct reject message is logged."""
 
         with mininode_lock:
             for tx in txs:
                 self.tx_store[tx.sha256] = tx
 
         def test():
             for tx in txs:
                 self.send_message(msg_tx(tx))
 
             if expect_disconnect:
                 self.wait_for_disconnect()
             else:
                 self.sync_with_ping()
 
             raw_mempool = node.getrawmempool()
             if success:
                 # Check that all txs are now in the mempool
                 for tx in txs:
                     assert tx.hash in raw_mempool, "{} not found in mempool".format(
                         tx.hash)
             else:
                 # Check that none of the txs are now in the mempool
                 for tx in txs:
                     assert tx.hash not in raw_mempool, "{} tx found in mempool".format(
                         tx.hash)
 
         if reject_reason:
             with node.assert_debug_log(expected_msgs=[reject_reason]):
                 test()
         else:
             test()
diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index ba05f425c..c91f5d4f8 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -1,590 +1,638 @@
 #!/usr/bin/env python3
 # Copyright (c) 2017-2019 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Class for bitcoind node under test"""
 
 import contextlib
 import decimal
 from enum import Enum
 import errno
 import http.client
 import json
 import logging
 import os
 import re
 import subprocess
 import sys
 import tempfile
 import time
 import urllib.parse
 import collections
 
 from .authproxy import JSONRPCException
 from .messages import COIN, CTransaction, FromHex
 from .util import (
     MAX_NODES,
     append_config,
     delete_cookie_file,
     get_rpc_proxy,
     p2p_port,
     rpc_url,
     wait_until,
 )
 
 BITCOIND_PROC_WAIT_TIMEOUT = 60
 
 
 class FailedToStartError(Exception):
     """Raised when a node fails to start correctly."""
 
 
 class ErrorMatch(Enum):
     FULL_TEXT = 1
     FULL_REGEX = 2
     PARTIAL_REGEX = 3
 
 
 class TestNode():
     """A class for representing a bitcoind node under test.
 
     This class contains:
 
     - state about the node (whether it's running, etc)
     - a Python subprocess.Popen object representing the running process
     - an RPC connection to the node
     - one or more P2P connections to the node
 
     To make things easier for the test writer, any unrecognised messages will
     be dispatched to the RPC connection."""
 
     def __init__(self, i, datadir, *, chain, host, rpc_port, p2p_port, timewait, bitcoind, bitcoin_cli,
                  coverage_dir, extra_conf=None, extra_args=None, use_cli=False, emulator=None):
         self.index = i
         self.datadir = datadir
         self.bitcoinconf = os.path.join(self.datadir, "bitcoin.conf")
         self.stdout_dir = os.path.join(self.datadir, "stdout")
         self.stderr_dir = os.path.join(self.datadir, "stderr")
         self.chain = chain
         self.host = host
         self.rpc_port = rpc_port
         self.p2p_port = p2p_port
         self.name = "testnode-{}".format(i)
         self.rpc_timeout = timewait
         self.binary = bitcoind
         if not os.path.isfile(self.binary):
             raise FileNotFoundError(
                 "Binary '{}' could not be found.\nTry setting it manually:\n\tBITCOIND=<path/to/bitcoind> {}".format(self.binary, sys.argv[0]))
         self.coverage_dir = coverage_dir
         if extra_conf is not None:
             append_config(datadir, extra_conf)
         # Most callers will just need to add extra args to the default list
         # below.
         # For those callers that need more flexibility, they can access the
         # default args using the provided facilities.
         # Note that common args are set in the config file (see
         # initialize_datadir)
         self.extra_args = extra_args
         self.default_args = [
             "-datadir=" + self.datadir,
             "-logtimemicros",
             "-debug",
             "-debugexclude=libevent",
             "-debugexclude=leveldb",
             "-uacomment=" + self.name,
             "-noprinttoconsole",
         ]
 
         if emulator is not None:
             if not os.path.isfile(emulator):
                 raise FileNotFoundError(
                     "Emulator '{}' could not be found.".format(emulator))
         self.emulator = emulator
 
         if use_cli and not os.path.isfile(bitcoin_cli):
             raise FileNotFoundError(
                 "Binary '{}' could not be found.\nTry setting it manually:\n\tBITCOINCLI=<path/to/bitcoin-cli> {}".format(bitcoin_cli, sys.argv[0]))
         self.cli = TestNodeCLI(bitcoin_cli, self.datadir, self.emulator)
         self.use_cli = use_cli
 
         self.running = False
         self.process = None
         self.rpc_connected = False
         self.rpc = None
         self.url = None
         self.relay_fee_cache = None
         self.log = logging.getLogger('TestFramework.node{}'.format(i))
         # Whether to kill the node when this object goes away
         self.cleanup_on_exit = True
         self.p2ps = []
 
     AddressKeyPair = collections.namedtuple(
         'AddressKeyPair', ['address', 'key'])
     PRIV_KEYS = [
         # address , privkey
         AddressKeyPair(
             'mjTkW3DjgyZck4KbiRusZsqTgaYTxdSz6z',
             'cVpF924EspNh8KjYsfhgY96mmxvT6DgdWiTYMtMjuM74hJaU5psW'),
         AddressKeyPair(
             'msX6jQXvxiNhx3Q62PKeLPrhrqZQdSimTg',
             'cUxsWyKyZ9MAQTaAhUQWJmBbSvHMwSmuv59KgxQV7oZQU3PXN3KE'),
         AddressKeyPair(
             'mnonCMyH9TmAsSj3M59DsbH8H63U3RKoFP',
             'cTrh7dkEAeJd6b3MRX9bZK8eRmNqVCMH3LSUkE3dSFDyzjU38QxK'),
         AddressKeyPair(
             'mqJupas8Dt2uestQDvV2NH3RU8uZh2dqQR',
             'cVuKKa7gbehEQvVq717hYcbE9Dqmq7KEBKqWgWrYBa2CKKrhtRim'),
         AddressKeyPair(
             'msYac7Rvd5ywm6pEmkjyxhbCDKqWsVeYws',
             'cQDCBuKcjanpXDpCqacNSjYfxeQj8G6CAtH1Dsk3cXyqLNC4RPuh'),
         AddressKeyPair(
             'n2rnuUnwLgXqf9kk2kjvVm8R5BZK1yxQBi',
             'cQakmfPSLSqKHyMFGwAqKHgWUiofJCagVGhiB4KCainaeCSxeyYq'),
         AddressKeyPair(
             'myzuPxRwsf3vvGzEuzPfK9Nf2RfwauwYe6',
             'cQMpDLJwA8DBe9NcQbdoSb1BhmFxVjWD5gRyrLZCtpuF9Zi3a9RK'),
         AddressKeyPair(
             'mumwTaMtbxEPUswmLBBN3vM9oGRtGBrys8',
             'cSXmRKXVcoouhNNVpcNKFfxsTsToY5pvB9DVsFksF1ENunTzRKsy'),
         AddressKeyPair(
             'mpV7aGShMkJCZgbW7F6iZgrvuPHjZjH9qg',
             'cSoXt6tm3pqy43UMabY6eUTmR3eSUYFtB2iNQDGgb3VUnRsQys2k'),
         AddressKeyPair(
             'mq4fBNdckGtvY2mijd9am7DRsbRB4KjUkf',
             'cN55daf1HotwBAgAKWVgDcoppmUNDtQSfb7XLutTLeAgVc3u8hik'),
         AddressKeyPair(
             'mpFAHDjX7KregM3rVotdXzQmkbwtbQEnZ6',
             'cT7qK7g1wkYEMvKowd2ZrX1E5f6JQ7TM246UfqbCiyF7kZhorpX3'),
         AddressKeyPair(
             'mzRe8QZMfGi58KyWCse2exxEFry2sfF2Y7',
             'cPiRWE8KMjTRxH1MWkPerhfoHFn5iHPWVK5aPqjW8NxmdwenFinJ'),
     ]
 
     def get_deterministic_priv_key(self):
         """Return a deterministic priv key in base58, that only depends on the node's index"""
         assert len(self.PRIV_KEYS) == MAX_NODES
         return self.PRIV_KEYS[self.index]
 
+    def get_mem_rss(self):
+        """Get the memory usage (RSS) per `ps`.
+
+        If process is stopped or `ps` is unavailable, return None.
+        """
+        if not (self.running and self.process):
+            self.log.warning(
+                "Couldn't get memory usage; process isn't running.")
+            return None
+
+        try:
+            return int(subprocess.check_output(
+                "ps h -o rss {}".format(self.process.pid),
+                shell=True, stderr=subprocess.DEVNULL).strip())
+
+        # Catching `Exception` broadly to avoid failing on platforms where ps
+        # isn't installed or doesn't work as expected, e.g. OpenBSD.
+        #
+        # We could later use something like `psutils` to work across platforms.
+        except Exception:
+            self.log.exception("Unable to get memory usage")
+            return None
+
     def _node_msg(self, msg: str) -> str:
         """Return a modified msg that identifies this node by its index as a debugging aid."""
         return "[node {}] {}".format(self.index, msg)
 
     def _raise_assertion_error(self, msg: str):
         """Raise an AssertionError with msg modified to identify this node."""
         raise AssertionError(self._node_msg(msg))
 
     def __del__(self):
         # Ensure that we don't leave any bitcoind processes lying around after
         # the test ends
         if self.process and self.cleanup_on_exit:
             # Should only happen on test failure
             # Avoid using logger, as that may have already been shutdown when
             # this destructor is called.
             print(self._node_msg("Cleaning up leftover process"))
             self.process.kill()
 
     def __getattr__(self, name):
         """Dispatches any unrecognised messages to the RPC connection or a CLI instance."""
         if self.use_cli:
             return getattr(self.cli, name)
         else:
             assert self.rpc is not None, self._node_msg(
                 "Error: RPC not initialized")
             assert self.rpc_connected, self._node_msg(
                 "Error: No RPC connection")
             return getattr(self.rpc, name)
 
     def clear_default_args(self):
         self.default_args.clear()
 
     def extend_default_args(self, args):
         self.default_args.extend(args)
 
     def remove_default_args(self, args):
         for rm_arg in args:
             # Remove all occurrences of rm_arg in self.default_args:
             #  - if the arg is a flag (-flag), then the names must match
             #  - if the arg is a value (-key=value) then the name must starts
             #    with "-key=" (the '"' char is to avoid removing "-key_suffix"
             #    arg is "-key" is the argument to remove).
             self.default_args = [def_arg for def_arg in self.default_args
                                  if rm_arg != def_arg and not def_arg.startswith(rm_arg + '=')]
 
     def start(self, extra_args=None, *, stdout=None,
               stderr=None, **kwargs):
         """Start the node."""
         if extra_args is None:
             extra_args = self.extra_args
 
         # Add a new stdout and stderr file each time bitcoind is started
         if stderr is None:
             stderr = tempfile.NamedTemporaryFile(
                 dir=self.stderr_dir, delete=False)
         if stdout is None:
             stdout = tempfile.NamedTemporaryFile(
                 dir=self.stdout_dir, delete=False)
         self.stderr = stderr
         self.stdout = stdout
 
         # Delete any existing cookie file -- if such a file exists (eg due to
         # unclean shutdown), it will get overwritten anyway by bitcoind, and
         # potentially interfere with our attempt to authenticate
         delete_cookie_file(self.datadir, self.chain)
 
         # add environment variable LIBC_FATAL_STDERR_=1 so that libc errors are
         # written to stderr and not the terminal
         subp_env = dict(os.environ, LIBC_FATAL_STDERR_="1")
 
         p_args = [self.binary] + self.default_args + extra_args
         if self.emulator is not None:
             p_args = [self.emulator] + p_args
         self.process = subprocess.Popen(
             p_args,
             env=subp_env,
             stdout=stdout,
             stderr=stderr,
             **kwargs)
 
         self.running = True
         self.log.debug("bitcoind started, waiting for RPC to come up")
 
     def wait_for_rpc_connection(self):
         """Sets up an RPC connection to the bitcoind process. Returns False if unable to connect."""
         # Poll at a rate of four times per second
         poll_per_s = 4
         for _ in range(poll_per_s * self.rpc_timeout):
             if self.process.poll() is not None:
                 raise FailedToStartError(self._node_msg(
                     'bitcoind exited with status {} during initialization'.format(self.process.returncode)))
             try:
                 rpc = get_rpc_proxy(
                     rpc_url(
                         self.datadir,
                         self.chain,
                         self.host,
                         self.rpc_port),
                     self.index,
                     timeout=self.rpc_timeout,
                     coveragedir=self.coverage_dir)
                 rpc.getblockcount()
                 # If the call to getblockcount() succeeds then the RPC
                 # connection is up
                 self.log.debug("RPC successfully started")
                 if self.use_cli:
                     return
                 self.rpc = rpc
                 self.rpc_connected = True
                 self.url = self.rpc.url
                 return
             except IOError as e:
                 if e.errno != errno.ECONNREFUSED:  # Port not yet open?
                     raise  # unknown IO error
             except JSONRPCException as e:  # Initialization phase
                 # -28 RPC in warmup
                 # -342 Service unavailable, RPC server started but is shutting down due to error
                 if e.error['code'] != -28 and e.error['code'] != -342:
                     raise  # unknown JSON RPC exception
             except ValueError as e:  # cookie file not found and no rpcuser or rpcassword. bitcoind still starting
                 if "No RPC credentials" not in str(e):
                     raise
             time.sleep(1.0 / poll_per_s)
         self._raise_assertion_error("Unable to connect to bitcoind")
 
     def generate(self, nblocks, maxtries=1000000):
         self.log.debug(
             "TestNode.generate() dispatches `generate` call to `generatetoaddress`")
         return self.generatetoaddress(
             nblocks=nblocks, address=self.get_deterministic_priv_key().address, maxtries=maxtries)
 
     def get_wallet_rpc(self, wallet_name):
         if self.use_cli:
             return self.cli("-rpcwallet={}".format(wallet_name))
         else:
             assert self.rpc is not None, self._node_msg(
                 "Error: RPC not initialized")
             assert self.rpc_connected, self._node_msg(
                 "Error: RPC not connected")
             wallet_path = "wallet/{}".format(urllib.parse.quote(wallet_name))
             return self.rpc / wallet_path
 
     def stop_node(self, expected_stderr='', wait=0):
         """Stop the node."""
         if not self.running:
             return
         self.log.debug("Stopping node")
         try:
             self.stop(wait=wait)
         except http.client.CannotSendRequest:
             self.log.exception("Unable to stop node.")
 
         # Check that stderr is as expected
         self.stderr.seek(0)
         stderr = self.stderr.read().decode('utf-8').strip()
         if stderr != expected_stderr:
             raise AssertionError(
                 "Unexpected stderr {} != {}".format(stderr, expected_stderr))
 
         self.stdout.close()
         self.stderr.close()
 
         del self.p2ps[:]
 
     def is_node_stopped(self):
         """Checks whether the node has stopped.
 
         Returns True if the node has stopped. False otherwise.
         This method is responsible for freeing resources (self.process)."""
         if not self.running:
             return True
         return_code = self.process.poll()
         if return_code is None:
             return False
 
         # process has stopped. Assert that it didn't return an error code.
         assert return_code == 0, self._node_msg(
             "Node returned non-zero exit code ({}) when stopping".format(return_code))
         self.running = False
         self.process = None
         self.rpc_connected = False
         self.rpc = None
         self.log.debug("Node stopped")
         return True
 
     def wait_until_stopped(self, timeout=BITCOIND_PROC_WAIT_TIMEOUT):
         wait_until(self.is_node_stopped, timeout=timeout)
 
     @contextlib.contextmanager
     def assert_debug_log(self, expected_msgs, unexpected_msgs=None, timeout=2):
         """Assert that some debug messages are present within some timeout.
         Unexpected debug messages may be optionally provided to fail a test
         if they appear before expected messages.
 
         Note: expected_msgs must always be non-empty even if the goal is to check
         for unexpected_msgs. This provides a bounded scenario such that "we expect
         to reach some target resulting in expected_msgs without seeing unexpected_msgs.
         Otherwise, we are testing that something never happens, which is fundamentally
         not robust test logic.
         """
         if not expected_msgs:
             raise AssertionError("Expected debug messages is empty")
         if unexpected_msgs is None:
             unexpected_msgs = []
         time_end = time.time() + timeout
         debug_log = os.path.join(self.datadir, self.chain, 'debug.log')
         with open(debug_log, encoding='utf-8') as dl:
             dl.seek(0, 2)
             prev_size = dl.tell()
 
         yield
 
         while True:
             found = True
             with open(debug_log, encoding='utf-8') as dl:
                 dl.seek(prev_size)
                 log = dl.read()
             print_log = " - " + "\n - ".join(log.splitlines())
             for unexpected_msg in unexpected_msgs:
                 if re.search(re.escape(unexpected_msg),
                              log, flags=re.MULTILINE):
                     self._raise_assertion_error(
                         'Unexpected message "{}" partially matches log:\n\n{}\n\n'.format(
                             unexpected_msg, print_log))
             for expected_msg in expected_msgs:
                 if re.search(re.escape(expected_msg), log,
                              flags=re.MULTILINE) is None:
                     found = False
             if found:
                 return
             if time.time() >= time_end:
                 break
             time.sleep(0.05)
         self._raise_assertion_error(
             'Expected messages "{}" does not partially match log:\n\n{}\n\n'.format(
                 str(expected_msgs), print_log))
 
+    @contextlib.contextmanager
+    def assert_memory_usage_stable(self, perc_increase_allowed=0.03):
+        """Context manager that allows the user to assert that a node's memory usage (RSS)
+        hasn't increased beyond some threshold percentage.
+        """
+        before_memory_usage = self.get_mem_rss()
+
+        yield
+
+        after_memory_usage = self.get_mem_rss()
+
+        if not (before_memory_usage and after_memory_usage):
+            self.log.warning(
+                "Unable to detect memory usage (RSS) - skipping memory check.")
+            return
+
+        perc_increase_memory_usage = 1 - \
+            (float(before_memory_usage) / after_memory_usage)
+
+        if perc_increase_memory_usage > perc_increase_allowed:
+            self._raise_assertion_error(
+                "Memory usage increased over threshold of {:.3f}% from {} to {} ({:.3f}%)".format(
+                    perc_increase_allowed * 100, before_memory_usage, after_memory_usage,
+                    perc_increase_memory_usage * 100))
+
     def assert_start_raises_init_error(
             self, extra_args=None, expected_msg=None, match=ErrorMatch.FULL_TEXT, *args, **kwargs):
         """Attempt to start the node and expect it to raise an error.
 
         extra_args: extra arguments to pass through to bitcoind
         expected_msg: regex that stderr should match when bitcoind fails
 
         Will throw if bitcoind starts without an error.
         Will throw if an expected_msg is provided and it does not match bitcoind's stdout."""
         with tempfile.NamedTemporaryFile(dir=self.stderr_dir, delete=False) as log_stderr, \
                 tempfile.NamedTemporaryFile(dir=self.stdout_dir, delete=False) as log_stdout:
             try:
                 self.start(extra_args, stdout=log_stdout,
                            stderr=log_stderr, *args, **kwargs)
                 self.wait_for_rpc_connection()
                 self.stop_node()
                 self.wait_until_stopped()
             except FailedToStartError as e:
                 self.log.debug('bitcoind failed to start: {}'.format(e))
                 self.running = False
                 self.process = None
                 # Check stderr for expected message
                 if expected_msg is not None:
                     log_stderr.seek(0)
                     stderr = log_stderr.read().decode('utf-8').strip()
                     if match == ErrorMatch.PARTIAL_REGEX:
                         if re.search(expected_msg, stderr,
                                      flags=re.MULTILINE) is None:
                             self._raise_assertion_error(
                                 'Expected message "{}" does not partially match stderr:\n"{}"'.format(expected_msg, stderr))
                     elif match == ErrorMatch.FULL_REGEX:
                         if re.fullmatch(expected_msg, stderr) is None:
                             self._raise_assertion_error(
                                 'Expected message "{}" does not fully match stderr:\n"{}"'.format(expected_msg, stderr))
                     elif match == ErrorMatch.FULL_TEXT:
                         if expected_msg != stderr:
                             self._raise_assertion_error(
                                 'Expected message "{}" does not fully match stderr:\n"{}"'.format(expected_msg, stderr))
             else:
                 if expected_msg is None:
                     assert_msg = "bitcoind should have exited with an error"
                 else:
                     assert_msg = "bitcoind should have exited with expected error " + expected_msg
                 self._raise_assertion_error(assert_msg)
 
     def relay_fee(self, cached=True):
         if not self.relay_fee_cache or not cached:
             self.relay_fee_cache = self.getnetworkinfo()["relayfee"]
 
         return self.relay_fee_cache
 
     def calculate_fee(self, tx):
         """ Estimate the necessary fees (in sats) for an unsigned CTransaction assuming:
         - the current relayfee on node
         - all inputs are compressed-key p2pkh, and will be signed ecdsa or schnorr
         - all inputs currently unsigned (empty scriptSig)
         """
         billable_size_estimate = tx.billable_size()
         # Add some padding for signatures / public keys
         # 107 = length of PUSH(longest_sig = 72 bytes), PUSH(pubkey = 33 bytes)
         billable_size_estimate += len(tx.vin) * 107
 
         # relay_fee gives a value in BCH per kB.
         return int(self.relay_fee() / 1000 * billable_size_estimate * COIN)
 
     def calculate_fee_from_txid(self, txid):
         ctx = FromHex(CTransaction(), self.getrawtransaction(txid))
         return self.calculate_fee(ctx)
 
     def add_p2p_connection(self, p2p_conn, *, wait_for_verack=True, **kwargs):
         """Add a p2p connection to the node.
 
         This method adds the p2p connection to the self.p2ps list and also
         returns the connection to the caller."""
         if 'dstport' not in kwargs:
             kwargs['dstport'] = p2p_port(self.index)
         if 'dstaddr' not in kwargs:
             kwargs['dstaddr'] = '127.0.0.1'
 
         p2p_conn.peer_connect(**kwargs)()
         self.p2ps.append(p2p_conn)
         if wait_for_verack:
             p2p_conn.wait_for_verack()
 
         return p2p_conn
 
     @property
     def p2p(self):
         """Return the first p2p connection
 
         Convenience property - most tests only use a single p2p connection to each
         node, so this saves having to write node.p2ps[0] many times."""
         assert self.p2ps, self._node_msg("No p2p connection")
         return self.p2ps[0]
 
     def disconnect_p2ps(self):
         """Close all p2p connections to the node."""
         for p in self.p2ps:
             p.peer_disconnect()
         del self.p2ps[:]
 
 
 class TestNodeCLIAttr:
     def __init__(self, cli, command):
         self.cli = cli
         self.command = command
 
     def __call__(self, *args, **kwargs):
         return self.cli.send_cli(self.command, *args, **kwargs)
 
     def get_request(self, *args, **kwargs):
         return lambda: self(*args, **kwargs)
 
 
 def arg_to_cli(arg):
     if isinstance(arg, bool):
         return str(arg).lower()
     elif isinstance(arg, dict) or isinstance(arg, list):
         return json.dumps(arg)
     else:
         return str(arg)
 
 
 class TestNodeCLI():
     """Interface to bitcoin-cli for an individual node"""
 
     def __init__(self, binary, datadir, emulator=None):
         self.options = []
         self.binary = binary
         self.datadir = datadir
         self.input = None
         self.log = logging.getLogger('TestFramework.bitcoincli')
         self.emulator = emulator
 
     def __call__(self, *options, input=None):
         # TestNodeCLI is callable with bitcoin-cli command-line options
         cli = TestNodeCLI(self.binary, self.datadir, self.emulator)
         cli.options = [str(o) for o in options]
         cli.input = input
         return cli
 
     def __getattr__(self, command):
         return TestNodeCLIAttr(self, command)
 
     def batch(self, requests):
         results = []
         for request in requests:
             try:
                 results.append(dict(result=request()))
             except JSONRPCException as e:
                 results.append(dict(error=e))
         return results
 
     def send_cli(self, command=None, *args, **kwargs):
         """Run bitcoin-cli command. Deserializes returned string as python object."""
         pos_args = [arg_to_cli(arg) for arg in args]
         named_args = [str(key) + "=" + arg_to_cli(value)
                       for (key, value) in kwargs.items()]
         assert not (
             pos_args and named_args), "Cannot use positional arguments and named arguments in the same bitcoin-cli call"
         p_args = [self.binary, "-datadir=" + self.datadir] + self.options
         if named_args:
             p_args += ["-named"]
         if command is not None:
             p_args += [command]
         p_args += pos_args + named_args
         if self.emulator is not None:
             p_args = [self.emulator] + p_args
         self.log.debug("Running bitcoin-cli command: {}".format(command))
         process = subprocess.Popen(p_args, stdin=subprocess.PIPE,
                                    stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
         cli_stdout, cli_stderr = process.communicate(input=self.input)
         returncode = process.poll()
         if returncode:
             match = re.match(
                 r'error code: ([-0-9]+)\nerror message:\n(.*)', cli_stderr)
             if match:
                 code, message = match.groups()
                 raise JSONRPCException(dict(code=int(code), message=message))
             # Ignore cli_stdout, raise with cli_stderr
             raise subprocess.CalledProcessError(
                 returncode, self.binary, output=cli_stderr)
         try:
             return json.loads(cli_stdout, parse_float=decimal.Decimal)
         except json.JSONDecodeError:
             return cli_stdout.rstrip("\n")