Update aliases event after deletion

Attempt to update the appropriate `m.room.aliases` event after deleting
an alias. This may fail due to the deleter not being in the room.

Will also check if the canonical alias of the event is set to the
deleted alias, and if so will attempt to delete it.

synapse/handlers/directory.py

@@ -32,6 +32,8 @@ class DirectoryHandler(BaseHandler):
     def __init__(self, hs):
         super(DirectoryHandler, self).__init__(hs)
 
+        self.state = hs.get_state_handler()
+
         self.federation = hs.get_replication_layer()
         self.federation.register_query_handler(
             "directory", self.on_directory_query
@@ -93,7 +95,7 @@ class DirectoryHandler(BaseHandler):
         yield self._create_association(room_alias, room_id, servers)
 
     @defer.inlineCallbacks
-    def delete_association(self, user_id, room_alias):
+    def delete_association(self, requester, user_id, room_alias):
         # association deletion for human users
 
         can_delete = yield self._user_can_delete_alias(room_alias, user_id)
@@ -112,7 +114,25 @@ class DirectoryHandler(BaseHandler):
                 errcode=Codes.EXCLUSIVE
             )
 
-        yield self._delete_association(room_alias)
+        room_id = yield self._delete_association(room_alias)
+
+        try:
+            yield self.send_room_alias_update_event(
+                requester,
+                requester.user.to_string(),
+                room_id
+            )
+
+            yield self._update_canonical_alias(
+                requester,
+                requester.user.to_string(),
+                room_id,
+                room_alias,
+            )
+        except AuthError as e:
+            logger.info("Failed to update alias events: %s", e)
+
+        defer.returnValue(room_id)
 
     @defer.inlineCallbacks
     def delete_appservice_association(self, service, room_alias):
@@ -129,11 +149,9 @@ class DirectoryHandler(BaseHandler):
         if not self.hs.is_mine(room_alias):
             raise SynapseError(400, "Room alias must be local")
 
-        yield self.store.delete_room_alias(room_alias)
+        room_id = yield self.store.delete_room_alias(room_alias)
 
-        # TODO - Looks like _update_room_alias_event has never been implemented
+        defer.returnValue(room_id)
-        # if room_id:
-        #    yield self._update_room_alias_events(user_id, room_id)
 
     @defer.inlineCallbacks
     def get_association(self, room_alias):
@@ -233,6 +251,28 @@ class DirectoryHandler(BaseHandler):
             ratelimit=False
         )
 
+    @defer.inlineCallbacks
+    def _update_canonical_alias(self, requester, user_id, room_id, room_alias):
+        alias_event = yield self.state.get_current_state(
+            room_id, EventTypes.CanonicalAlias, ""
+        )
+
+        if alias_event.content.get("alias", "") != room_alias.to_string():
+            return
+
+        msg_handler = self.hs.get_handlers().message_handler
+        yield msg_handler.create_and_send_nonmember_event(
+            requester,
+            {
+                "type": EventTypes.CanonicalAlias,
+                "state_key": "",
+                "room_id": room_id,
+                "sender": user_id,
+                "content": {},
+            },
+            ratelimit=False
+        )
+
     @defer.inlineCallbacks
     def get_association_from_room_alias(self, room_alias):
         result = yield self.store.get_association_from_room_alias(

synapse/rest/client/v1/directory.py

@@ -127,8 +127,9 @@ class ClientDirectoryServer(ClientV1RestServlet):
         room_alias = RoomAlias.from_string(room_alias)
 
         yield dir_handler.delete_association(
-            user.to_string(), room_alias
+            requester, user.to_string(), room_alias
         )
+
         logger.info(
             "User %s deleted alias %s",
             user.to_string(),