Add option to disable search room lists

This disables both local and remote room list searching.

docs/sample_config.yaml

@@ -1036,6 +1036,11 @@ password_config:
 
 
 
+# Wether the public room list can be searched. When disabled blocks
+# searching local and remote room list for local and remote users.
+#
+#enable_room_list_search: true
+
 # The `alias_creation` option controls who's allowed to create aliases
 # on this server.
 #

synapse/config/room_directory.py

@@ -20,6 +20,10 @@ from ._base import Config, ConfigError
 
 class RoomDirectoryConfig(Config):
     def read_config(self, config):
+        self.enable_room_list_search = config.get(
+            "enable_room_list_search", True,
+        )
+
         alias_creation_rules = config.get("alias_creation_rules")
 
         if alias_creation_rules is not None:
@@ -54,6 +58,11 @@ class RoomDirectoryConfig(Config):
 
     def default_config(self, config_dir_path, server_name, **kwargs):
         return """
+        # Wether the public room list can be searched. When disabled blocks
+        # searching local and remote room list for local and remote users.
+        #
+        #enable_room_list_search: true
+
         # The `alias_creation` option controls who's allowed to create aliases
         # on this server.
         #

synapse/handlers/room_list.py

@@ -44,6 +44,7 @@ EMPTY_THIRD_PARTY_ID = ThirdPartyInstanceID(None, None)
 class RoomListHandler(BaseHandler):
     def __init__(self, hs):
         super(RoomListHandler, self).__init__(hs)
+        self.config = hs.config
         self.response_cache = ResponseCache(hs, "room_list")
         self.remote_response_cache = ResponseCache(hs, "remote_room_list",
                                                    timeout_ms=30 * 1000)
@@ -70,6 +71,12 @@ class RoomListHandler(BaseHandler):
             "Getting public room list: limit=%r, since=%r, search=%r, network=%r",
             limit, since_token, bool(search_filter), network_tuple,
         )
+        if not self.config.enable_room_list_search:
+            return defer.succeed({
+                "chunk": [],
+                "total_room_count_estimate": 0,
+            })
+
         if search_filter:
             # We explicitly don't bother caching searches or requests for
             # appservice specific lists.
@@ -441,6 +448,12 @@ class RoomListHandler(BaseHandler):
     def get_remote_public_room_list(self, server_name, limit=None, since_token=None,
                                     search_filter=None, include_all_networks=False,
                                     third_party_instance_id=None,):
+        if not self.config.enable_room_list_search:
+            defer.returnValue({
+                "chunk": [],
+                "total_room_count_estimate": 0,
+            })
+
         if search_filter:
             # We currently don't support searching across federation, so we have
             # to do it manually without pagination