Untested approach for MSC2174

synapse/api/room_versions.py

@@ -68,6 +68,8 @@ class RoomVersion:
     limit_notifications_power_levels: bool
     # MSC2174/MSC2176: Apply updated redaction rules algorithm.
     msc2176_redaction_rules: bool
+    # MSC2174: Move `redacts` into `content`
+    msc2174_redacts_key_content: bool
     # MSC3083: Support the 'restricted' join_rule.
     msc3083_join_rules: bool
     # MSC3375: Support for the proper redaction rules for MSC3083. This mustn't
@@ -94,6 +96,7 @@ class RoomVersions:
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
         msc2176_redaction_rules=False,
+        msc2174_redacts_key_content=False,
         msc3083_join_rules=False,
         msc3375_redaction_rules=False,
         msc2403_knocking=False,
@@ -110,6 +113,7 @@ class RoomVersions:
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
         msc2176_redaction_rules=False,
+        msc2174_redacts_key_content=False,
         msc3083_join_rules=False,
         msc3375_redaction_rules=False,
         msc2403_knocking=False,
@@ -126,6 +130,7 @@ class RoomVersions:
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
         msc2176_redaction_rules=False,
+        msc2174_redacts_key_content=False,
         msc3083_join_rules=False,
         msc3375_redaction_rules=False,
         msc2403_knocking=False,
@@ -142,6 +147,7 @@ class RoomVersions:
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
         msc2176_redaction_rules=False,
+        msc2174_redacts_key_content=False,
         msc3083_join_rules=False,
         msc3375_redaction_rules=False,
         msc2403_knocking=False,
@@ -158,6 +164,7 @@ class RoomVersions:
         strict_canonicaljson=False,
         limit_notifications_power_levels=False,
         msc2176_redaction_rules=False,
+        msc2174_redacts_key_content=False,
         msc3083_join_rules=False,
         msc3375_redaction_rules=False,
         msc2403_knocking=False,
@@ -174,6 +181,7 @@ class RoomVersions:
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
         msc2176_redaction_rules=False,
+        msc2174_redacts_key_content=False,
         msc3083_join_rules=False,
         msc3375_redaction_rules=False,
         msc2403_knocking=False,
@@ -190,6 +198,25 @@ class RoomVersions:
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
         msc2176_redaction_rules=True,
+        msc2174_redacts_key_content=False,
+        msc3083_join_rules=False,
+        msc3375_redaction_rules=False,
+        msc2403_knocking=False,
+        msc2716_historical=False,
+        msc2716_redactions=False,
+    )
+    MSC2174 = RoomVersion(
+        # v6 + MSC2174
+        "org.matrix.msc2174",
+        RoomDisposition.UNSTABLE,
+        EventFormatVersions.V3,
+        StateResolutionVersions.V2,
+        enforce_key_validity=True,
+        special_case_aliases_auth=False,
+        strict_canonicaljson=True,
+        limit_notifications_power_levels=True,
+        msc2176_redaction_rules=False,
+        msc2174_redacts_key_content=True,
         msc3083_join_rules=False,
         msc3375_redaction_rules=False,
         msc2403_knocking=False,
@@ -206,6 +233,7 @@ class RoomVersions:
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
         msc2176_redaction_rules=False,
+        msc2174_redacts_key_content=False,
         msc3083_join_rules=False,
         msc3375_redaction_rules=False,
         msc2403_knocking=True,
@@ -222,6 +250,7 @@ class RoomVersions:
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
         msc2176_redaction_rules=False,
+        msc2174_redacts_key_content=False,
         msc3083_join_rules=True,
         msc3375_redaction_rules=False,
         msc2403_knocking=True,
@@ -238,6 +267,7 @@ class RoomVersions:
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
         msc2176_redaction_rules=False,
+        msc2174_redacts_key_content=False,
         msc3083_join_rules=True,
         msc3375_redaction_rules=True,
         msc2403_knocking=True,
@@ -254,6 +284,7 @@ class RoomVersions:
         strict_canonicaljson=True,
         limit_notifications_power_levels=True,
         msc2176_redaction_rules=False,
+        msc2174_redacts_key_content=False,
         msc3083_join_rules=False,
         msc3375_redaction_rules=False,
         msc2403_knocking=True,
@@ -272,6 +303,7 @@ class RoomVersions:
         RoomVersions.V5,
         RoomVersions.V6,
         RoomVersions.MSC2176,
+        RoomVersions.MSC2174,
         RoomVersions.V7,
         RoomVersions.V8,
         RoomVersions.V9,

synapse/event_auth.py

@@ -579,6 +579,8 @@ def check_redaction(
 
     if room_version_obj.event_format == EventFormatVersions.V1:
         redacter_domain = get_domain_from_id(event.event_id)
+        # Note: Room versions with v1-formatted events *cannot* have the
+        # `redacts` key in `content` from MSC2174/MSC2176.
         if not isinstance(event.redacts, str):
             return False
         redactee_domain = get_domain_from_id(event.redacts)

synapse/events/utils.py

@@ -386,6 +386,15 @@ def serialize_event(
             raise TypeError("only_event_fields must be a list of strings")
         d = only_fields(d, only_event_fields)
 
+    if d["content"] is not None and e.type == EventTypes.Redaction:
+        # If the redacts key is in the `content`, copy it to the top level for
+        # older clients. Similarly, if the redacts key is already at the top
+        # level then copy it to `content` for newer clients.
+        if e.room_version.msc2174_redacts_key_content:
+            d["redacts"] = d["content"]["redacts"]
+        else:
+            d["content"]["redacts"] = d["redacts"]
+
     return d
 
 

synapse/handlers/message.py

@@ -1403,10 +1403,14 @@ async def persist_and_notify_client_event(
             # user is actually admin or not).
             is_admin_redaction = False
             if event.type == EventTypes.Redaction:
-                assert event.redacts is not None
+                redacts = event.redacts
+                if event.room_version.msc2174_redacts_key_content:
+                    redacts = event.content["redacts"]
+
+                assert redacts is not None
 
                 original_event = await self.store.get_event(
-                    event.redacts,
+                    redacts,
                     redact_behaviour=EventRedactBehaviour.as_is,
                     get_prev_content=False,
                     allow_rejected=False,
@@ -1500,10 +1504,13 @@ async def persist_and_notify_client_event(
                 )
 
         if event.type == EventTypes.Redaction:
-            assert event.redacts is not None
+            redacts = event.redacts
+            if event.room_version.msc2174_redacts_key_content:
+                redacts = event.content["redacts"]
+            assert redacts is not None
 
             original_event = await self.store.get_event(
-                event.redacts,
+                redacts,
                 redact_behaviour=EventRedactBehaviour.as_is,
                 get_prev_content=False,
                 allow_rejected=False,
@@ -1560,7 +1567,7 @@ async def persist_and_notify_client_event(
                 # checks on the original event. Let's start by checking the original
                 # event exists.
                 if not original_event:
-                    raise NotFoundError("Could not find event %s" % (event.redacts,))
+                    raise NotFoundError("Could not find event %s" % (redacts,))
 
                 if event.user_id != original_event.user_id:
                     raise AuthError(403, "You don't have permission to redact events")

synapse/storage/databases/main/cache.py

@@ -125,6 +125,7 @@ def process_replication_rows(
                     row.room_id,
                     row.type,
                     row.state_key,
+                    # TODO: Support `redacts` being in `content` rather than at the top level.
                     row.redacts,
                     row.relates_to,
                     backfilled=True,
@@ -159,6 +160,7 @@ def _process_event_stream_row(self, token: int, row: EventsStreamRow) -> None:
                 data.room_id,
                 data.type,
                 data.state_key,
+                # TODO: Support `redacts` being in `content` rather than at the top level.
                 data.redacts,
                 data.relates_to,
                 backfilled=False,

synapse/storage/databases/main/events.py

@@ -1538,15 +1538,18 @@ def _update_metadata_tables_txn(
             return
 
         for event, _ in events_and_contexts:
-            if event.type == EventTypes.Redaction and event.redacts is not None:
+            redacts = event.redacts
+            if event.room_version.msc2174_redacts_key_content:
+                redacts = event.content["redacts"]
+            if event.type == EventTypes.Redaction and redacts is not None:
                 # Remove the entries in the event_push_actions table for the
                 # redacted event.
                 self._remove_push_actions_for_event_id_txn(
-                    txn, event.room_id, event.redacts
+                    txn, event.room_id, redacts
                 )
 
                 # Remove from relations table.
-                self._handle_redact_relations(txn, event.redacts)
+                self._handle_redact_relations(txn, redacts)
 
         # Update the event_forward_extremities, event_backward_extremities and
         # event_edges tables.
@@ -1564,9 +1567,13 @@ def _update_metadata_tables_txn(
             elif event.type == EventTypes.Message:
                 # Insert into the event_search table.
                 self._store_room_message_txn(txn, event)
-            elif event.type == EventTypes.Redaction and event.redacts is not None:
-                # Insert into the redactions table.
-                self._store_redaction(txn, event)
+            elif event.type == EventTypes.Redaction:
+                redacts = event.redacts
+                if event.room_version.msc2174_redacts_key_content:
+                    redacts = event.content["redacts"]
+                if redacts is not None:
+                    # Insert into the redactions table.
+                    self._store_redaction(txn, event)
             elif event.type == EventTypes.Retention:
                 # Update the room_retention table.
                 self._store_retention_policy_for_room_txn(txn, event)
@@ -1617,6 +1624,7 @@ def _add_to_cache(self, txn, events_and_contexts):
         if not ev_map:
             return
 
+        # TODO: Support `redacts` being in `content` rather than at the top level.
         sql = (
             "SELECT "
             " e.event_id as event_id, "
@@ -1648,18 +1656,22 @@ def prefill():
         txn.call_after(prefill)
 
     def _store_redaction(self, txn: LoggingTransaction, event: EventBase) -> None:
+        redacts = event.redacts
+        if event.room_version.msc2174_redacts_key_content:
+            redacts = event.content["redacts"]
+
         # Invalidate the caches for the redacted event, note that these caches
         # are also cleared as part of event replication in _invalidate_caches_for_event.
-        txn.call_after(self.store._invalidate_get_event_cache, event.redacts)
-        txn.call_after(self.store.get_relations_for_event.invalidate, (event.redacts,))
-        txn.call_after(self.store.get_applicable_edit.invalidate, (event.redacts,))
+        txn.call_after(self.store._invalidate_get_event_cache, redacts)
+        txn.call_after(self.store.get_relations_for_event.invalidate, (redacts,))
+        txn.call_after(self.store.get_applicable_edit.invalidate, (redacts,))
 
         self.db_pool.simple_upsert_txn(
             txn,
             table="redactions",
             keyvalues={"event_id": event.event_id},
             values={
-                "redacts": event.redacts,
+                "redacts": redacts,
                 "received_ts": self._clock.time_msec(),
             },
         )

synapse/storage/databases/main/events_bg_updates.py

@@ -635,6 +635,7 @@ async def _event_fix_redactions_bytes(
 
         def _event_fix_redactions_bytes_txn(txn: LoggingTransaction) -> None:
             # This update is quite fast due to new index.
+            # TODO: Support `redacts` being in `content` rather than at the top level.
             txn.execute(
                 """
                 UPDATE event_json

synapse/storage/databases/main/events_worker.py

@@ -497,7 +497,10 @@ async def get_events_as_list(
             # we have to recheck auth now.
 
             if not allow_rejected and entry.event.type == EventTypes.Redaction:
-                if entry.event.redacts is None:
+                redacted_event_id = entry.event.redacts
+                if entry.event.room_version.msc2174_redacts_key_content:
+                    redacted_event_id = entry.event.content["redacts"]
+                if redacted_event_id is None:
                     # A redacted redaction doesn't have a `redacts` key, in
                     # which case lets just withhold the event.
                     #
@@ -511,7 +514,6 @@ async def get_events_as_list(
                     )
                     continue
 
-                redacted_event_id = entry.event.redacts
                 event_map = await self._get_events_from_cache_or_db([redacted_event_id])
                 original_event_entry = event_map.get(redacted_event_id)
                 if not original_event_entry: