Remove the ability to query relations when the original event was redacted. (#5629)

Fixes #5594

Forbid viewing relations on an event once it has been redacted.

1 files changed, 12 insertions, 4 deletions

diff --git a/synapse/events/utils.py b/synapse/events/utils.py

index 987de5cab7..9487a886f5 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -52,10 +52,15 @@ def prune_event(event):
 
     from . import event_type_from_format_version
 
-    return event_type_from_format_version(event.format_version)(
+    pruned_event = event_type_from_format_version(event.format_version)(
         pruned_event_dict, event.internal_metadata.get_dict()
     )
 
+    # Mark the event as redacted
+    pruned_event.internal_metadata.redacted = True
+
+    return pruned_event
+
 
 def prune_event_dict(event_dict):
     """Redacts the event_dict in the same way as `prune_event`, except it
@@ -360,9 +365,12 @@ class EventClientSerializer(object):
         event_id = event.event_id
         serialized_event = serialize_event(event, time_now, **kwargs)
 
-        # If MSC1849 is enabled then we need to look if thre are any relations
-        # we need to bundle in with the event
-        if self.experimental_msc1849_support_enabled and bundle_aggregations:
+        # If MSC1849 is enabled then we need to look if there are any relations
+        # we need to bundle in with the event.
+        # Do not bundle relations if the event has been redacted
+        if not event.internal_metadata.is_redacted() and (
+            self.experimental_msc1849_support_enabled and bundle_aggregations
+        ):
             annotations = yield self.store.get_aggregation_groups_for_event(event_id)
             references = yield self.store.get_relations_for_event(
                 event_id, RelationTypes.REFERENCE, direction="f"