From a2bb50c2eb431414d999ec682b236620528b00e1 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Wed, 9 Oct 2019 15:39:13 +0100
Subject: [PATCH] Merge pull request #6185 from
 matrix-org/erikj/fix_censored_evnets

Fix inserting bytes as text in `censor_redactions`
---
 changelog.d/6185.bugfix                       |  1 +
 synapse/storage/events.py                     |  6 ++---
 .../redaction_censor3_fix_update.sql.postgres | 26 +++++++++++++++++++
 3 files changed, 29 insertions(+), 4 deletions(-)
 create mode 100644 changelog.d/6185.bugfix
 create mode 100644 synapse/storage/schema/delta/56/redaction_censor3_fix_update.sql.postgres

diff --git a/changelog.d/6185.bugfix b/changelog.d/6185.bugfix
new file mode 100644
index 000000000..9d1c669b8
--- /dev/null
+++ b/changelog.d/6185.bugfix
@@ -0,0 +1 @@
+Fix bug where redacted events were sometimes incorrectly censored in the database, breaking APIs that attempted to fetch such events.
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index 2e485c864..bb6ff0595 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -23,7 +23,7 @@ from functools import wraps
 from six import iteritems, text_type
 from six.moves import range
 
-from canonicaljson import encode_canonical_json, json
+from canonicaljson import json
 from prometheus_client import Counter, Histogram
 
 from twisted.internet import defer
@@ -1632,9 +1632,7 @@ class EventsStore(
                 and original_event.internal_metadata.is_redacted()
             ):
                 # Redaction was allowed
-                pruned_json = encode_canonical_json(
-                    prune_event_dict(original_event.get_dict())
-                )
+                pruned_json = encode_json(prune_event_dict(original_event.get_dict()))
             else:
                 # Redaction wasn't allowed
                 pruned_json = None
diff --git a/synapse/storage/schema/delta/56/redaction_censor3_fix_update.sql.postgres b/synapse/storage/schema/delta/56/redaction_censor3_fix_update.sql.postgres
new file mode 100644
index 000000000..f7bcc5e2f
--- /dev/null
+++ b/synapse/storage/schema/delta/56/redaction_censor3_fix_update.sql.postgres
@@ -0,0 +1,26 @@
+/* Copyright 2019 The Matrix.org Foundation C.I.C.
+ *
+ * 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.
+ */
+
+
+-- There was a bug where we may have updated censored redactions as bytes,
+-- which can (somehow) cause json to be inserted hex encoded. This goes and
+-- undoes any such hex encoded JSON.
+UPDATE event_json SET json = convert_from(json::bytea, 'utf8')
+WHERE event_id IN (
+  SELECT event_json.event_id
+  FROM event_json
+  INNER JOIN redactions ON (event_json.event_id = redacts)
+  WHERE have_censored AND json NOT LIKE '{%'
+);