room: mark encryption state as missing if a room thinks it's not encrypted after requesting it

crates/matrix-sdk/src/room/mod.rs

@@ -1575,6 +1575,25 @@ impl Room {
             // could be quite useful if someone wants to enable encryption and
             // send a message right after it's enabled.
             _ = timeout(self.client.inner.sync_beat.listen(), SYNC_WAIT_TIME).await;
+
+            // If after waiting for a sync, we don't have the encryption state we expect,
+            // assume the local encryption state is incorrect; this will cause
+            // the SDK to re-request it later for confirmation, instead of
+            // assuming it's sync'd and correct (and not encrypted).
+            let _sync_lock = self.client.base_client().sync_lock().lock().await;
+            if !self.inner.is_encrypted() {
+                debug!("still not marked as encrypted, marking encryption state as missing");
+
+                let mut room_info = self.clone_info();
+                room_info.mark_encryption_state_missing();
+                let mut changes = StateChanges::default();
+                changes.add_room(room_info.clone());
+
+                self.client.store().save_changes(&changes).await?;
+                self.set_room_info(room_info, RoomInfoNotableUpdateReasons::empty());
+            } else {
+                debug!("room successfully marked as encrypted");
+            }
         }
 
         Ok(())

crates/matrix-sdk/tests/integration/room/joined.rs

@@ -761,3 +761,37 @@ async fn test_make_reply_event_doesnt_require_event_cache() {
     // make_edit_event works, even if the event cache hasn't been enabled.
     room.make_edit_event(resp_event_id, EditedContent::RoomMessage(new_content)).await.unwrap();
 }
+
+#[async_test]
+async fn test_enable_encryption_doesnt_stay_unencrypted() {
+    let (client, server) = logged_in_client_with_server().await;
+
+    mock_encryption_state(&server, false).await;
+
+    Mock::given(method("PUT"))
+        .and(path_regex(r"^/_matrix/client/r0/rooms/.*/state/m.*room.*encryption.?"))
+        .and(header("authorization", "Bearer 1234"))
+        .respond_with(ResponseTemplate::new(200).set_body_json(json!({ "event_id": "$1"})))
+        .mount(&server)
+        .await;
+
+    let room_id = room_id!("!a:b.c");
+    let room = mock_sync_with_new_room(
+        |builder| {
+            builder.add_joined_room(JoinedRoomBuilder::new(room_id));
+        },
+        &client,
+        &server,
+        room_id,
+    )
+    .await;
+
+    assert!(!room.is_encrypted().await.unwrap());
+
+    room.enable_encryption().await.expect("enabling encryption should work");
+
+    server.reset().await;
+    mock_encryption_state(&server, true).await;
+
+    assert!(room.is_encrypted().await.unwrap());
+}