Merge #14522: tests: add invalid P2P message tests

d20a9fa13d tests: add tests for invalid P2P messages (James O'Beirne)
62f94d39f8 tests: add P2PConnection.send_raw_message (James O'Beirne)
5aa31f6ef2 tests: add utility to assert node memory usage hasn't increased (James O'Beirne)

Pull request description:

  - Adds `p2p_invalid_messages.py`: tests based on behavior for dealing with invalid and malformed P2P messages. Includes a test verifying that we can't DoS a node by spamming it with large invalid messages.
  - Adds `TestNode.assert_memory_usage_stable`: a context manager that allows us to ensure memory usage doesn't significantly increase on a node during some test.
  - Adds `P2PConnection.send_raw_message`: which allows us to construct and send messages with tweaked headers.

Tree-SHA512: 720a4894c1e6d8f1551b2ae710e5b06c9e4f281524623957cb01599be9afea82671dc26d6152281de0acb87720f0c53b61e2b27d40434d30e525dd9e31fa671f

test/functional/test_framework/mininode.py

@@ -207,10 +207,13 @@ class P2PConnection(asyncio.Protocol):
 
         This method takes a P2P payload, builds the P2P header and adds
         the message to the send buffer to be sent over the socket."""
+        tmsg = self.build_message(message)
+        self._log_message("send", message)
+        return self.send_raw_message(tmsg)
+
+    def send_raw_message(self, raw_message_bytes):
         if not self.is_connected:
             raise IOError('Not connected')
-        self._log_message("send", message)
-        tmsg = self._build_message(message)
 
         def maybe_write():
             if not self._transport:
@@ -220,12 +223,12 @@ class P2PConnection(asyncio.Protocol):
             # Python 3.4 versions.
             if hasattr(self._transport, 'is_closing') and 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()
@@ -409,9 +412,9 @@ class P2PInterface(P2PConnection):
 
     # 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):

test/functional/test_framework/test_node.py

@@ -115,6 +115,28 @@ class TestNode():
         ]
         return 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 %d] %s" % (self.index, msg)
@@ -271,6 +293,29 @@ class TestNode():
                 if re.search(re.escape(expected_msg), log, flags=re.MULTILINE) is None:
                     self._raise_assertion_error('Expected message "{}" does not partially match log:\n\n{}\n\n'.format(expected_msg, 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.