From 6b5f4aa0a9c16fa0b3a5252ad5e60802adb05ac0 Mon Sep 17 00:00:00 2001
From: Michael Telatynski <7t3chguy@gmail.com>
Date: Thu, 5 May 2022 07:14:23 +0100
Subject: [PATCH] Prune both clear & wire content on redaction (#2346)

---
 spec/unit/models/event.spec.ts | 27 +++++++++++++++++++++++++++
 src/models/event.ts            | 22 ++++++++++------------
 2 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/spec/unit/models/event.spec.ts b/spec/unit/models/event.spec.ts
index f1a8969ddfd..7f2b263137c 100644
--- a/spec/unit/models/event.spec.ts
+++ b/spec/unit/models/event.spec.ts
@@ -57,4 +57,31 @@ describe('MatrixEvent', () => {
         expect(a.toSnapshot().isEquivalentTo(a)).toBe(true);
         expect(a.toSnapshot().isEquivalentTo(b)).toBe(false);
     });
+
+    it("should prune clearEvent when being redacted", () => {
+        const ev = new MatrixEvent({
+            type: "m.room.message",
+            content: {
+                body: "Test",
+            },
+            event_id: "$event1:server",
+        });
+
+        expect(ev.getContent().body).toBe("Test");
+        expect(ev.getWireContent().body).toBe("Test");
+        ev.makeEncrypted("m.room.encrypted", { ciphertext: "xyz" }, "", "");
+        expect(ev.getContent().body).toBe("Test");
+        expect(ev.getWireContent().body).toBeUndefined();
+        expect(ev.getWireContent().ciphertext).toBe("xyz");
+
+        const redaction = new MatrixEvent({
+            type: "m.room.redaction",
+            redacts: ev.getId(),
+        });
+
+        ev.makeRedacted(redaction);
+        expect(ev.getContent().body).toBeUndefined();
+        expect(ev.getWireContent().body).toBeUndefined();
+        expect(ev.getWireContent().ciphertext).toBeUndefined();
+    });
 });
diff --git a/src/models/event.ts b/src/models/event.ts
index bcfaab9c658..227036be5e7 100644
--- a/src/models/event.ts
+++ b/src/models/event.ts
@@ -1112,23 +1112,21 @@ export class MatrixEvent extends TypedEventEmitter<EmittedEvents, MatrixEventHan
         }
         this.event.unsigned.redacted_because = redactionEvent.event as IEvent;
 
-        let key;
-        for (key in this.event) {
-            if (!this.event.hasOwnProperty(key)) {
-                continue;
-            }
-            if (!REDACT_KEEP_KEYS.has(key)) {
+        for (const key in this.event) {
+            if (this.event.hasOwnProperty(key) && !REDACT_KEEP_KEYS.has(key)) {
                 delete this.event[key];
             }
         }
 
+        // If the event is encrypted prune the decrypted bits
+        if (this.isEncrypted()) {
+            this.clearEvent = null;
+        }
+
         const keeps = REDACT_KEEP_CONTENT_MAP[this.getType()] || {};
         const content = this.getContent();
-        for (key in content) {
-            if (!content.hasOwnProperty(key)) {
-                continue;
-            }
-            if (!keeps[key]) {
+        for (const key in content) {
+            if (content.hasOwnProperty(key) && !keeps[key]) {
                 delete content[key];
             }
         }
@@ -1589,7 +1587,7 @@ const REDACT_KEEP_KEYS = new Set([
     'content', 'unsigned', 'origin_server_ts',
 ]);
 
-// a map from event type to the .content keys we keep when an event is redacted
+// a map from state event type to the .content keys we keep when an event is redacted
 const REDACT_KEEP_CONTENT_MAP = {
     [EventType.RoomMember]: { 'membership': 1 },
     [EventType.RoomCreate]: { 'creator': 1 },