Remove `room_version` param from `validate_event_for_room_version`

Instead, use the `room_version` property of the event we're validating.

The `room_version` was originally added as a parameter somewhere around #4482,
but really it's been redundant since #6875 added a `room_version` field to `EventBase`.

synapse/event_auth.py

@@ -45,9 +45,7 @@ if typing.TYPE_CHECKING:
 logger = logging.getLogger(__name__)
 
 
-def validate_event_for_room_version(
-    room_version_obj: RoomVersion, event: "EventBase"
-) -> None:
+def validate_event_for_room_version(event: "EventBase") -> None:
     """Ensure that the event complies with the limits, and has the right signatures
 
     NB: does not *validate* the signatures - it assumes that any signatures present
@@ -60,12 +58,10 @@ def validate_event_for_room_version(
     NB: This is used to check events that have been received over federation. As such,
     it can only enforce the checks specified in the relevant room version, to avoid
     a split-brain situation where some servers accept such events, and others reject
-    them.
-
-    TODO: consider moving this into EventValidator
+    them. See also EventValidator, which contains extra checks which are applied only to
+    locally-generated events.
 
     Args:
-        room_version_obj: the version of the room which contains this event
         event: the event to be checked
 
     Raises:
@@ -103,7 +99,7 @@ def validate_event_for_room_version(
             raise AuthError(403, "Event not signed by sending server")
 
     is_invite_via_allow_rule = (
-        room_version_obj.msc3083_join_rules
+        event.room_version.msc3083_join_rules
         and event.type == EventTypes.Member
         and event.membership == Membership.JOIN
         and EventContentFields.AUTHORISING_USER in event.content

synapse/events/validator.py

@@ -35,6 +35,10 @@ class EventValidator:
     def validate_new(self, event: EventBase, config: HomeServerConfig) -> None:
         """Validates the event has roughly the right format
 
+        Suitable for checking a locally-created event. It has stricter checks than
+        is appropriate for an event received over federation (for which, see
+        event_auth.validate_event_for_room_version)
+
         Args:
             event: The event to validate.
             config: The homeserver's configuration.

synapse/handlers/federation.py

@@ -1206,7 +1206,7 @@ class FederationHandler:
             event.internal_metadata.send_on_behalf_of = self.hs.hostname
 
             try:
-                validate_event_for_room_version(room_version_obj, event)
+                validate_event_for_room_version(event)
                 await self._event_auth_handler.check_auth_rules_from_context(
                     room_version_obj, event, context
                 )
@@ -1258,7 +1258,7 @@ class FederationHandler:
         )
 
         try:
-            validate_event_for_room_version(room_version_obj, event)
+            validate_event_for_room_version(event)
             await self._event_auth_handler.check_auth_rules_from_context(
                 room_version_obj, event, context
             )

synapse/handlers/federation_event.py

@@ -1453,7 +1453,7 @@ class FederationEventHandler:
 
                 context = EventContext.for_outlier(self._storage_controllers)
                 try:
-                    validate_event_for_room_version(room_version_obj, event)
+                    validate_event_for_room_version(event)
                     check_auth_rules_for_event(room_version_obj, event, auth)
                 except AuthError as e:
                     logger.warning("Rejecting %r because %s", event, e)
@@ -1501,7 +1501,7 @@ class FederationEventHandler:
         room_version_obj = KNOWN_ROOM_VERSIONS[room_version]
 
         try:
-            validate_event_for_room_version(room_version_obj, event)
+            validate_event_for_room_version(event)
         except AuthError as e:
             logger.warning("While validating received event %r: %s", event, e)
             # TODO: use a different rejected reason here?

synapse/handlers/message.py

@@ -1297,7 +1297,7 @@ class EventCreationHandler:
             assert event.content["membership"] == Membership.LEAVE
         else:
             try:
-                validate_event_for_room_version(room_version_obj, event)
+                validate_event_for_room_version(event)
                 await self._event_auth_handler.check_auth_rules_from_context(
                     room_version_obj, event, context
                 )

synapse/handlers/room.py

@@ -227,7 +227,7 @@ class RoomCreationHandler:
             },
         )
         old_room_version = await self.store.get_room_version(old_room_id)
-        validate_event_for_room_version(old_room_version, tombstone_event)
+        validate_event_for_room_version(tombstone_event)
         await self._event_auth_handler.check_auth_rules_from_context(
             old_room_version, tombstone_event, tombstone_context
         )