From 3ff6433fab7a88b8904a8f93c100f89b6f14a8c6 Mon Sep 17 00:00:00 2001
From: skeh <skeh@is.nota.live>
Date: Thu, 1 Dec 2022 07:45:08 +0000
Subject: [PATCH] Merge pull request 'hotfix/misskey-forkbomb' (#8) from
 hotfix/misskey-forkbomb into stage

Reviewed-on: https://code.vtopia.live/Vtopia/MissV/pulls/8
---
 .../backend/src/remote/activitypub/kernel/update/index.ts | 2 +-
 packages/backend/src/remote/activitypub/models/person.ts  | 8 ++++----
 .../backend/src/remote/activitypub/models/question.ts     | 4 ++--
 packages/backend/src/remote/activitypub/resolver.ts       | 8 ++++++--
 4 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/packages/backend/src/remote/activitypub/kernel/update/index.ts b/packages/backend/src/remote/activitypub/kernel/update/index.ts
index 9e8a81bb39..022be0ad8e 100644
--- a/packages/backend/src/remote/activitypub/kernel/update/index.ts
+++ b/packages/backend/src/remote/activitypub/kernel/update/index.ts
@@ -26,7 +26,7 @@ export default async (actor: CacheableRemoteUser, activity: IUpdate): Promise<st
 		await updatePerson(actor.uri!, resolver, object);
 		return `ok: Person updated`;
 	} else if (getApType(object) === 'Question') {
-		await updateQuestion(object).catch(e => console.log(e));
+		await updateQuestion(object, resolver).catch(e => console.log(e));
 		return `ok: Question updated`;
 	} else {
 		return `skip: Unknown type: ${getApType(object)}`;
diff --git a/packages/backend/src/remote/activitypub/models/person.ts b/packages/backend/src/remote/activitypub/models/person.ts
index 6097e3b6ed..5ef04588e9 100644
--- a/packages/backend/src/remote/activitypub/models/person.ts
+++ b/packages/backend/src/remote/activitypub/models/person.ts
@@ -271,7 +271,7 @@ export async function createPerson(uri: string, resolver?: Resolver): Promise<Us
 	});
 	//#endregion
 
-	await updateFeatured(user!.id).catch(err => logger.error(err));
+	await updateFeatured(user!.id, resolver).catch(err => logger.error(err));
 
 	return user!;
 }
@@ -384,7 +384,7 @@ export async function updatePerson(uri: string, resolver?: Resolver | null, hint
 		followerSharedInbox: person.sharedInbox || (person.endpoints ? person.endpoints.sharedInbox : undefined),
 	});
 
-	await updateFeatured(exist.id).catch(err => logger.error(err));
+	await updateFeatured(exist.id, resolver).catch(err => logger.error(err));
 }
 
 /**
@@ -462,14 +462,14 @@ export function analyzeAttachments(attachments: IObject | IObject[] | undefined)
 	return { fields, services };
 }
 
-export async function updateFeatured(userId: User['id']) {
+export async function updateFeatured(userId: User['id'], resolver?: Resolver) {
 	const user = await Users.findOneByOrFail({ id: userId });
 	if (!Users.isRemoteUser(user)) return;
 	if (!user.featured) return;
 
 	logger.info(`Updating the featured: ${user.uri}`);
 
-	const resolver = new Resolver();
+	if (resolver == null) resolver = new Resolver();
 
 	// Resolve to (Ordered)Collection Object
 	const collection = await resolver.resolveCollection(user.featured);
diff --git a/packages/backend/src/remote/activitypub/models/question.ts b/packages/backend/src/remote/activitypub/models/question.ts
index f0321fdf2f..94a50d4f71 100644
--- a/packages/backend/src/remote/activitypub/models/question.ts
+++ b/packages/backend/src/remote/activitypub/models/question.ts
@@ -40,7 +40,7 @@ export async function extractPollFromQuestion(source: string | IObject, resolver
  * @param uri URI of AP Question object
  * @returns true if updated
  */
-export async function updateQuestion(value: any) {
+export async function updateQuestion(value: any, resolver?: Resolver) {
 	const uri = typeof value === 'string' ? value : value.id;
 
 	// URIがこのサーバーを指しているならスキップ
@@ -55,7 +55,7 @@ export async function updateQuestion(value: any) {
 	//#endregion
 
 	// resolve new Question object
-	const resolver = new Resolver();
+	if (resolver == null) resolver = new Resolver();
 	const question = await resolver.resolve(value) as IQuestion;
 	apLogger.debug(`fetched question: ${JSON.stringify(question, null, 2)}`);
 
diff --git a/packages/backend/src/remote/activitypub/resolver.ts b/packages/backend/src/remote/activitypub/resolver.ts
index 5c9d44292e..94227e4db5 100644
--- a/packages/backend/src/remote/activitypub/resolver.ts
+++ b/packages/backend/src/remote/activitypub/resolver.ts
@@ -19,9 +19,11 @@ import renderFollow from '@/remote/activitypub/renderer/follow.js';
 export default class Resolver {
 	private history: Set<string>;
 	private user?: ILocalUser;
+	private recursionLimit?: number;
 
-	constructor() {
+	constructor(recursionLimit = 100) {
 		this.history = new Set();
+		this.recursionLimit = recursionLimit;
 	}
 
 	public getHistory(): string[] {
@@ -59,7 +61,9 @@ export default class Resolver {
 		if (this.history.has(value)) {
 			throw new Error('cannot resolve already resolved one');
 		}
-
+		if (this.recursionLimit && this.history.size > this.recursionLimit) {
+			throw new Error('hit recursion limit');
+		}
 		this.history.add(value);
 
 		const host = extractDbHost(value);