From 7e5a8b8feb2acaac02045987c87ef567eb94c6b1 Mon Sep 17 00:00:00 2001
From: Half-Shot <will@half-shot.uk>
Date: Wed, 18 Sep 2024 10:08:03 +0100
Subject: [PATCH 1/2] Retry a join on invite if the response was M_FORBIDDEN

---
 src/room/useLoadGroupCall.ts | 47 ++++++++++++++++++++++++++++++++----
 1 file changed, 42 insertions(+), 5 deletions(-)

diff --git a/src/room/useLoadGroupCall.ts b/src/room/useLoadGroupCall.ts
index 8b758726..eacf090a 100644
--- a/src/room/useLoadGroupCall.ts
+++ b/src/room/useLoadGroupCall.ts
@@ -17,7 +17,7 @@ import { SyncState } from "matrix-js-sdk/src/sync";
 import { MatrixRTCSession } from "matrix-js-sdk/src/matrixrtc/MatrixRTCSession";
 import { RoomEvent, Room } from "matrix-js-sdk/src/models/room";
 import { KnownMembership } from "matrix-js-sdk/src/types";
-import { JoinRule } from "matrix-js-sdk/src/matrix";
+import { JoinRule, MatrixError } from "matrix-js-sdk/src/matrix";
 import { useTranslation } from "react-i18next";
 
 import { widget } from "../widget";
@@ -54,6 +54,40 @@ export type GroupCallStatus =
   | GroupCallWaitForInvite
   | GroupCallCanKnock;
 
+const MAX_RETRIES_FOR_INVITE_JOIN_FAILURE = 3;
+
+/**
+ * Join a room, and retry on M_FORBIDDEN error in order to work
+ * around a potential race when joining rooms over federation.
+ *
+ * Will retry up to `MAX_RETRIES_FOR_INVITE_JOIN_FAILURE` times.
+ *
+ * @see https://github.com/element-hq/element-call/issues/2634
+ * @param client The matrix client
+ * @param retries Number of attempts made.
+ * @param params Parameters to pass to client.joinRoom
+ */
+async function joinRoomAfterInvite(
+  client: MatrixClient,
+  retries = 0,
+  ...params: Parameters<MatrixClient["joinRoom"]>
+): ReturnType<MatrixClient["joinRoom"]> {
+  try {
+    return await client.joinRoom(...params);
+  } catch (ex) {
+    if (
+      ex instanceof MatrixError &&
+      ex.errcode === "M_FORBIDDEN" &&
+      retries < MAX_RETRIES_FOR_INVITE_JOIN_FAILURE
+    ) {
+      // If we were invited and got a M_FORBIDDEN, it's highly likely the server hasn't caught up yet.
+      await new Promise((r) => setTimeout(r, 5000));
+      return joinRoomAfterInvite(client, retries + 1, ...params);
+    }
+    throw ex;
+  }
+}
+
 export class CallTerminatedMessage extends Error {
   /**
    * @param messageBody The message explaining the kind of termination (kick, ban, knock reject, etc.) (translated)
@@ -162,10 +196,13 @@ export const useLoadGroupCall = (
               membership === KnownMembership.Invite &&
               prevMembership === KnownMembership.Knock
             ) {
-              client.joinRoom(room.roomId, { viaServers }).then((room) => {
-                logger.log("Auto-joined %s", room.roomId);
-                resolve(room);
-              }, reject);
+              joinRoomAfterInvite(client, 0, room.roomId, { viaServers }).then(
+                (room) => {
+                  logger.log("Auto-joined %s", room.roomId);
+                  resolve(room);
+                },
+                reject,
+              );
             }
             if (membership === KnownMembership.Ban) reject(bannedError());
             if (membership === KnownMembership.Leave)

From c19645c7108f5f530fbe62e39eed969df14adc00 Mon Sep 17 00:00:00 2001
From: Half-Shot <will@half-shot.uk>
Date: Wed, 18 Sep 2024 10:10:29 +0100
Subject: [PATCH 2/2] consts

---
 src/room/useLoadGroupCall.ts | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/room/useLoadGroupCall.ts b/src/room/useLoadGroupCall.ts
index eacf090a..6e07aa52 100644
--- a/src/room/useLoadGroupCall.ts
+++ b/src/room/useLoadGroupCall.ts
@@ -54,22 +54,24 @@ export type GroupCallStatus =
   | GroupCallWaitForInvite
   | GroupCallCanKnock;
 
-const MAX_RETRIES_FOR_INVITE_JOIN_FAILURE = 3;
+const MAX_ATTEMPTS_FOR_INVITE_JOIN_FAILURE = 3;
+const DELAY_MS_FOR_INVITE_JOIN_FAILURE = 3000;
 
 /**
  * Join a room, and retry on M_FORBIDDEN error in order to work
  * around a potential race when joining rooms over federation.
  *
- * Will retry up to `MAX_RETRIES_FOR_INVITE_JOIN_FAILURE` times.
+ * Will wait up to to `DELAY_MS_FOR_INVITE_JOIN_FAILURE` per attempt.
+ * Will try up to `MAX_ATTEMPTS_FOR_INVITE_JOIN_FAILURE` times.
  *
  * @see https://github.com/element-hq/element-call/issues/2634
  * @param client The matrix client
- * @param retries Number of attempts made.
+ * @param attempt Number of attempts made.
  * @param params Parameters to pass to client.joinRoom
  */
 async function joinRoomAfterInvite(
   client: MatrixClient,
-  retries = 0,
+  attempt = 0,
   ...params: Parameters<MatrixClient["joinRoom"]>
 ): ReturnType<MatrixClient["joinRoom"]> {
   try {
@@ -78,11 +80,11 @@ async function joinRoomAfterInvite(
     if (
       ex instanceof MatrixError &&
       ex.errcode === "M_FORBIDDEN" &&
-      retries < MAX_RETRIES_FOR_INVITE_JOIN_FAILURE
+      attempt < MAX_ATTEMPTS_FOR_INVITE_JOIN_FAILURE
     ) {
       // If we were invited and got a M_FORBIDDEN, it's highly likely the server hasn't caught up yet.
-      await new Promise((r) => setTimeout(r, 5000));
-      return joinRoomAfterInvite(client, retries + 1, ...params);
+      await new Promise((r) => setTimeout(r, DELAY_MS_FOR_INVITE_JOIN_FAILURE));
+      return joinRoomAfterInvite(client, attempt + 1, ...params);
     }
     throw ex;
   }