packages/backend/src/models/entities/user.ts

@@ -1,4 +1,4 @@
-import { Entity, Column, Index, OneToOne, JoinColumn, PrimaryColumn } from 'typeorm';
+import { Entity, Column, Index, OneToOne, ManyToOne, JoinColumn, PrimaryColumn } from 'typeorm';
 import { id } from '../id.js';
 import { DriveFile } from './drive-file.js';
 
@@ -230,6 +230,18 @@ export class User {
 	})
 	public federateBlocks: boolean;
 
+	@Column({
+		...id(),
+		nullable: true,
+	})
+	public movedToId: User['id'] | null;
+
+	@ManyToOne(() => User, {
+		onDelete: 'SET NULL'
+	})
+	@JoinColumn()
+	public movedTo: User | null;
+
 	constructor(data: Partial<User>) {
 		if (data == null) return;
 

packages/backend/src/remote/activitypub/kernel/index.ts

@@ -4,7 +4,7 @@ import { Resolver } from '@/remote/activitypub/resolver.js';
 import { extractDbHost } from '@/misc/convert-host.js';
 import { shouldBlockInstance } from '@/misc/should-block-instance.js';
 import { apLogger } from '../logger.js';
-import { IObject, isCreate, isDelete, isUpdate, isRead, isFollow, isAccept, isReject, isAdd, isRemove, isAnnounce, isLike, isUndo, isBlock, isCollectionOrOrderedCollection, isCollection, isFlag, getApId } from '../type.js';
+import { IObject, isCreate, isDelete, isUpdate, isRead, isFollow, isAccept, isReject, isAdd, isRemove, isAnnounce, isLike, isUndo, isBlock, isCollectionOrOrderedCollection, isCollection, isFlag, isMove, getApId } from '../type.js';
 import create from './create/index.js';
 import performDeleteActivity from './delete/index.js';
 import performUpdateActivity from './update/index.js';
@@ -19,6 +19,7 @@ import add from './add/index.js';
 import remove from './remove/index.js';
 import block from './block/index.js';
 import flag from './flag/index.js';
+import { move } from './move/index.js';
 
 export async function performActivity(actor: CacheableRemoteUser, activity: IObject, resolver: Resolver): Promise<void> {
 	if (isCollectionOrOrderedCollection(activity)) {
@@ -73,6 +74,8 @@ async function performOneActivity(actor: CacheableRemoteUser, activity: IObject,
 		await block(actor, activity);
 	} else if (isFlag(activity)) {
 		await flag(actor, activity);
+	} else if (isMove(activity)) {
+		await move(actor, activity, resolver);
 	} else {
 		apLogger.warn(`unrecognized activity type: ${(activity as any).type}`);
 	}

packages/backend/src/remote/activitypub/kernel/move/index.ts

@@ -0,0 +1,62 @@
+import { IsNull } from 'typeorm';
+import { CacheableRemoteUser } from '@/models/entities/user.js';
+import { resolvePerson } from '@/remote/activitypub/models/person.js';
+import { Followings, Users } from '@/models/index.js';
+import { createNotification } from '@/services/create-notification.js';
+import Resolver from '../../resolver.js';
+import { IMove, isActor, getApId } from '../../type.js';
+
+export async function move(actor: CacheableRemoteUser, activity: IMove, resolver: Resolver): Promise<void> {
+	// actor is not move origin
+	if (activity.object == null || getApId(activity.object) !== actor.uri) return;
+
+	// actor already moved
+	if (actor.movedTo != null) return;
+
+	// no move target
+	if (activity.target == null) return;
+
+	/* the database resolver can not be used here, because:
+	 * 1. It must be ensured that the latest data is used.
+	 * 2. The AP representation is needed, because `alsoKnownAs`
+	 *    is not stored in the database.
+	 * This also checks whether the move target is blocked
+	 */
+	const movedToAp = await resolver.resolve(getApId(activity.target));
+
+	// move target is not an actor
+	if (!isActor(movedToAp)) return;
+
+	// move destination has not accepted
+	if (!Array.isArray(movedToAp.alsoKnownAs) || !movedToAp.alsoKnownAs.includes(actor.id)) return;
+
+	// ensure the user exists
+	const movedTo = await resolvePerson(getApId(activity.target), resolver, movedToAp);
+	// move target is already suspended
+	if (movedTo.isSuspended) return;
+
+	// process move for local followers
+	const followings = Followings.find({
+		select: {
+			followerId: true,
+		},
+		where: {
+			followeeId: actor.id,
+			followerHost: IsNull(),
+		},
+	});
+
+	await Promise.all([
+		Users.update(actor.id, {
+			movedToId: movedTo.id,
+		}),
+		...followings.map(async (following) => {
+			// TODO: autoAcceptMove?
+
+			await createNotification(following.followerId, 'move', {
+				notifierId: actor.id,
+				moveTargetId: movedTo.id,
+			});
+		}),
+	]);
+}

packages/backend/src/remote/activitypub/type.ts

@@ -296,6 +296,10 @@ export interface IFlag extends IActivity {
 	type: 'Flag';
 }
 
+export interface IMove extends IActivity {
+	type: 'Move';
+}
+
 export const isCreate = (object: IObject): object is ICreate => getApType(object) === 'Create';
 export const isDelete = (object: IObject): object is IDelete => getApType(object) === 'Delete';
 export const isUpdate = (object: IObject): object is IUpdate => getApType(object) === 'Update';
@@ -310,6 +314,7 @@ export const isLike = (object: IObject): object is ILike => getApType(object) ==
 export const isAnnounce = (object: IObject): object is IAnnounce => getApType(object) === 'Announce';
 export const isBlock = (object: IObject): object is IBlock => getApType(object) === 'Block';
 export const isFlag = (object: IObject): object is IFlag => getApType(object) === 'Flag';
+export const isMove = (object: IObject): object is IMove => getApType(object) === 'Move';
 
 export interface ILink {
 	href: string;