feat: if an incoming remote message is too long, don't create the room, but notify the local recipients instead

closes #13174

public/language/en-GB/error.json

@@ -194,6 +194,7 @@
 	"cant-add-users-to-chat-room": "Can't add users to chat room.",
 	"cant-remove-users-from-chat-room": "Can't remove users from chat room.",
 	"chat-room-name-too-long": "Chat room name too long. Names can't be longer than %1 characters.",
+	"remote-chat-received-too-long": "You received a chat message from %1, but it was too long and was rejected.",
 
 	"already-voting-for-this-post": "You have already voted for this post.",
 	"reputation-system-disabled": "Reputation system is disabled.",

src/activitypub/notes.js

@@ -9,6 +9,7 @@ const meta = require('../meta');
 const privileges = require('../privileges');
 const categories = require('../categories');
 const messaging = require('../messaging');
+const notifications = require('../notifications');
 const user = require('../user');
 const topics = require('../topics');
 const posts = require('../posts');
@@ -288,6 +289,20 @@ Notes.assertPrivate = async (object) => {
 
 	const payload = await activitypub.mocks.message(object);
 
+	try {
+		await messaging.checkContent(payload.content, false);
+	} catch (e) {
+		const { displayname, userslug } = await user.getUserFields(payload.uid, ['displayname', 'userslug']);
+		const notification = await notifications.create({
+			bodyShort: `[[error:remote-chat-received-too-long, ${displayname}]]`,
+			path: `/user/${userslug}`,
+			nid: `error:chat:uid:${payload.uid}`,
+			from: payload.uid,
+		});
+		notifications.push(notification, Array.from(recipients).filter(uid => utils.isNumber(uid)));
+		return null;
+	}
+
 	if (!roomId) {
 		roomId = await messaging.newRoom(payload.uid, { uids: [...recipients] });
 	}