Add sanity checks to prevent users from ignoring themselves (#30079)

* Fix missing state

* Throw error if membership event changes

* Write test

* Fix broken tests

* Cache inviter when room is loaded

* Translate error message for dialog

src/components/structures/RoomView.tsx

@@ -370,6 +370,10 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
     private unmounted = false;
     private permalinkCreators: Record<string, RoomPermalinkCreator> = {};
 
+    // The userId from which we received this invite.
+    // Only populated if the membership of our user is invite.
+    private inviter?: string;
+
     private roomView = createRef<HTMLDivElement>();
     private searchResultsPanel = createRef<ScrollPanel>();
     private messagePanel: TimelinePanel | null = null;
@@ -1350,6 +1354,11 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
     // after a successful peek, or after we join the room).
     private onRoomLoaded = (room: Room): void => {
         if (this.unmounted) return;
+
+        // Store the inviter so that we can know who invited us to this room even if
+        // the membership event changes.
+        this.inviter = this.getInviterFromRoom(room);
+
         // Attach a widget store listener only when we get a room
         this.context.widgetLayoutStore.on(WidgetLayoutStore.emissionForRoom(room), this.onWidgetLayoutChange);
 
@@ -1729,8 +1738,20 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         });
     };
 
+    private getInviterFromRoom(room: Room): string | undefined {
+        const ownUserId = this.context.client?.getSafeUserId();
+        if (!ownUserId) return;
+
+        const myMember = room.getMember(ownUserId);
+        const memberEvent = myMember?.events.member;
+        const senderId = memberEvent?.getSender();
+
+        if (memberEvent?.getContent().membership === KnownMembership.Invite) return senderId;
+    }
+
     private onDeclineAndBlockButtonClicked = async (): Promise<void> => {
         if (!this.state.room || !this.context.client) return;
+
         const [shouldReject, ignoreUser, reportRoom] = await Modal.createDialog(DeclineAndBlockInviteDialog, {
             roomName: this.state.room.name,
         }).finished;
@@ -1745,11 +1766,20 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         const actions: Promise<unknown>[] = [];
 
         if (ignoreUser) {
-            const myMember = this.state.room.getMember(this.context.client!.getSafeUserId());
-            const inviteEvent = myMember!.events.member;
-            const ignoredUsers = this.context.client.getIgnoredUsers();
-            ignoredUsers.push(inviteEvent!.getSender()!); // de-duped internally in the js-sdk
-            actions.push(this.context.client.setIgnoredUsers(ignoredUsers));
+            const doIgnore = async (): Promise<void> => {
+                const ownUserId = this.context.client!.getSafeUserId();
+                if (!this.inviter || this.inviter === ownUserId) {
+                    // This is unlikely to happen since we cache the inviter as early as possible.
+                    // However, we still do this check here to be double sure.
+                    throw new CannotDetermineUserError(
+                        "Cannot determine which user to ignore since the member event has changed.",
+                    );
+                }
+                const ignoredUsers = this.context.client!.getIgnoredUsers();
+                ignoredUsers.push(this.inviter); // de-duped internally in the js-sdk
+                await this.context.client!.setIgnoredUsers(ignoredUsers);
+            };
+            actions.push(doIgnore());
         }
 
         if (reportRoom !== false) {
@@ -1766,7 +1796,14 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         } catch (error) {
             logger.error(`Failed to reject invite: ${error}`);
 
-            const msg = error instanceof Error ? error.message : JSON.stringify(error);
+            let msg: string = "";
+            if (error instanceof CannotDetermineUserError) {
+                msg = _t("room|failed_determine_user");
+            } else if (error instanceof Error) {
+                msg = error.message;
+            } else {
+                msg = JSON.stringify(error);
+            }
             Modal.createDialog(ErrorDialog, {
                 title: _t("room|failed_reject_invite"),
                 description: msg,
@@ -1783,6 +1820,9 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
             return;
         }
         try {
+            this.setState({
+                rejecting: true,
+            });
             await this.context.client.leave(this.state.room.roomId);
             defaultDispatcher.dispatch({ action: Action.ViewHomePage });
             this.setState({
@@ -2612,3 +2652,7 @@ export class RoomView extends React.Component<IRoomProps, IRoomState> {
         );
     }
 }
+
+class CannotDetermineUserError extends Error {
+    public name = "CannotDetermineUserError";
+}