Ignore incoming presence updates when presence is disabled (#7508)

changelog.d/7508.bugfix

@@ -0,0 +1 @@
+Ignore incoming presence events from other homeservers if presence is disabled locally.

synapse/handlers/presence.py

@@ -204,6 +204,7 @@ class PresenceHandler(BasePresenceHandler):
         self.notifier = hs.get_notifier()
         self.federation = hs.get_federation_sender()
         self.state = hs.get_state_handler()
+        self._presence_enabled = hs.config.use_presence
 
         federation_registry = hs.get_federation_registry()
 
@@ -676,13 +677,14 @@ class PresenceHandler(BasePresenceHandler):
     async def incoming_presence(self, origin, content):
         """Called when we receive a `m.presence` EDU from a remote server.
         """
+        if not self._presence_enabled:
+            return
+
         now = self.clock.time_msec()
         updates = []
         for push in content.get("push", []):
             # A "push" contains a list of presence that we are probably interested
             # in.
-            # TODO: Actually check if we're interested, rather than blindly
-            # accepting presence updates.
             user_id = push.get("user_id", None)
             if not user_id:
                 logger.info(