Last finalized batches received from other nodes should be verified before being used

[abramsymons]

Nodes should not trust other nodes when they get the last finalized batches from them and should verify their finalization signature.

zsequencer/node/tasks.py

Lines 403 to 422 in 9fc7309

	def find_all_nodes_last_finalized_batch(app_name: str) -> dict[str, Any]:
	"""Find the last finalized batch from all nodes."""
	last_finalized_batch: dict[str, Any] = zdb.get_last_batch(
	app_name=app_name, state="finalized"
	)
	for node in list(zconfig.NODES.values()):
	if node["id"] == zconfig.NODE["id"]:
	continue
	url: str = f'{node["socket"]}/node/{app_name}/batches/finalized/last'
	try:
	response: dict[str, Any] = requests.get(
	url=url, headers=zconfig.HEADERS
	).json()
	if response["status"] == "error":
	continue
	batch: dict[str, Any] = response["data"]
	if batch.get("index", 0) > last_finalized_batch.get("index", 0):
	last_finalized_batch = batch