Honour ratelimit flag for application services for invite ratelimiting (#9302)

2 files changed, 12 insertions, 4 deletions

diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index dbdfd56ff5..eddc7582d0 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -1619,7 +1619,9 @@ class FederationHandler(BaseHandler):
 
         # We retrieve the room member handler here as to not cause a cyclic dependency
         member_handler = self.hs.get_room_member_handler()
-        member_handler.ratelimit_invite(event.room_id, event.state_key)
+        # We don't rate limit based on room ID, as that should be done by
+        # sending server.
+        member_handler.ratelimit_invite(None, event.state_key)
 
         # keep a record of the room version, if we don't yet know it.
         # (this may get overwritten if we later get a different room version in a
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index d335da6f19..a5da97cfe0 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -155,10 +155,14 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
         """
         raise NotImplementedError()
 
-    def ratelimit_invite(self, room_id: str, invitee_user_id: str):
+    def ratelimit_invite(self, room_id: Optional[str], invitee_user_id: str):
         """Ratelimit invites by room and by target user.
+
+        If room ID is missing then we just rate limit by target user.
         """
-        self._invites_per_room_limiter.ratelimit(room_id)
+        if room_id:
+            self._invites_per_room_limiter.ratelimit(room_id)
+
         self._invites_per_user_limiter.ratelimit(invitee_user_id)
 
     async def _local_membership_update(
@@ -406,7 +410,9 @@ class RoomMemberHandler(metaclass=abc.ABCMeta):
         if effective_membership_state == Membership.INVITE:
             target_id = target.to_string()
             if ratelimit:
-                self.ratelimit_invite(room_id, target_id)
+                # Don't ratelimit application services.
+                if not requester.app_service or requester.app_service.is_rate_limited():
+                    self.ratelimit_invite(room_id, target_id)
 
             # block any attempts to invite the server notices mxid
             if target_id == self._server_notices_mxid: