Synapse accepts optional unspecced servers field in PUT directory/room/{roomAlias}

[DMRobertson]

Spec: https://spec.matrix.org/v1.4/client-server-api/#put_matrixclientv3directoryroomroomalias

synapse/synapse/rest/client/directory.py

Lines 74 to 89 in 6b99a66

	servers = content["servers"] if "servers" in content else None
	logger.debug("Got room_id: %s", room_id)
	logger.debug("Got servers: %s", servers)
	# TODO(erikj): Check types.
	room = await self.store.get_room(room_id)
	if room is None:
	raise SynapseError(400, "Room does not exist")
	requester = await self.auth.get_user_by_req(request)
	await self.directory_handler.create_association(
	requester, room_alias_obj, room_id, servers
	)

Forwarded to here

synapse/synapse/handlers/directory.py

Line 173 in 1a209ef

await self._create_association(room_alias, room_id, servers, creator=user_id)

and to here

synapse/synapse/handlers/directory.py

Lines 93 to 95 in 1a209ef

	await self.store.create_room_alias_association(
	room_alias, room_id, servers, creator=creator
	)

and eventually written to the database here

synapse/synapse/storage/databases/main/directory.py

Lines 112 to 117 in 3e0536c

	self.db_pool.simple_insert_many_txn(
	txn,
	table="room_alias_servers",
	keys=("room_alias", "server"),
	values=[(room_alias.to_string(), server) for server in servers],
	)

[DMRobertson]

Should be easy enough to drop this: we can simply ignore the field.

[DMRobertson]

But first we should check to see if it's in use in a meaningful way (i.e. in a way that differs to what servers=None would provide).