diff --git a/synapse/events/utils.py b/synapse/events/utils.py
new file mode 100644
index 0000000000..412f690f08
--- /dev/null
+++ b/synapse/events/utils.py
@@ -0,0 +1,82 @@
+# -*- coding: utf-8 -*-
+# Copyright 2014 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from synapse.api.constants import EventTypes
+
+
+def prune_event(event):
+ """ Returns a pruned version of the given event, which removes all keys we
+ don't know about or think could potentially be dodgy.
+
+ This is used when we "redact" an event. We want to remove all fields that
+ the user has specified, but we do want to keep necessary information like
+ type, state_key etc.
+ """
+ event_type = event.type
+
+ allowed_keys = [
+ "event_id",
+ "sender",
+ "room_id",
+ "hashes",
+ "signatures",
+ "content",
+ "type",
+ "state_key",
+ "depth",
+ "prev_events",
+ "prev_state",
+ "auth_events",
+ "origin",
+ "origin_server_ts",
+ ]
+
+ new_content = {}
+
+ def add_fields(*fields):
+ for field in fields:
+ if field in event.content:
+ new_content[field] = event.content[field]
+
+ if event_type == EventTypes.Member:
+ add_fields("membership")
+ elif event_type == EventTypes.Create:
+ add_fields("creator")
+ elif event_type == EventTypes.JoinRules:
+ add_fields("join_rule")
+ elif event_type == EventTypes.PowerLevels:
+ add_fields(
+ "users",
+ "users_default",
+ "events",
+ "events_default",
+ "events_default",
+ "state_default",
+ "ban",
+ "kick",
+ "redact",
+ )
+ elif event_type == EventTypes.Aliases:
+ add_fields("aliases")
+
+ allowed_fields = {
+ k: v
+ for k, v in event.get_dict().items()
+ if k in allowed_keys
+ }
+
+ allowed_fields["content"] = new_content
+
+ return type(event)(allowed_fields)
|
