From 11b3d4fa0a881c555c70af9879b022e037325c09 Mon Sep 17 00:00:00 2001
From: Laura Hausmann <laura@hausmann.dev>
Date: Wed, 18 Oct 2023 23:58:56 +0200
Subject: [PATCH] [backend] Require users to be followed before adding them to
 lists

---
 .../queue/processors/db/import-user-lists.ts  | 17 +++++++++++++++-
 .../server/api/endpoints/users/lists/push.ts  | 20 +++++++++++++++++--
 .../src/server/api/mastodon/helpers/list.ts   |  9 ++++++++-
 .../backend/src/services/user-list/push.ts    |  3 ++-
 4 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/packages/backend/src/queue/processors/db/import-user-lists.ts b/packages/backend/src/queue/processors/db/import-user-lists.ts
index 0c23f0699..68ba001ec 100644
--- a/packages/backend/src/queue/processors/db/import-user-lists.ts
+++ b/packages/backend/src/queue/processors/db/import-user-lists.ts
@@ -10,7 +10,7 @@ import {
 	DriveFiles,
 	Users,
 	UserLists,
-	UserListJoinings,
+	UserListJoinings, Blockings, Followings,
 } from "@/models/index.js";
 import { genId } from "@/misc/gen-id.js";
 import type { DbUserImportJobData } from "@/queue/types.js";
@@ -77,6 +77,21 @@ export async function importUserLists(
 				target = await resolveUser(username, host);
 			}
 
+			const isBlocked = await Blockings.exist({
+				where: {
+					blockerId: target.id,
+					blockeeId: user.id,
+				},
+			});
+			const isFollowed = await Followings.exist({
+				where: {
+					followerId: user.id,
+					followeeId: target.id,
+				},
+			});
+
+			if (isBlocked || !isFollowed) continue;
+
 			if (
 				(await UserListJoinings.findOneBy({
 					userListId: list!.id,
diff --git a/packages/backend/src/server/api/endpoints/users/lists/push.ts b/packages/backend/src/server/api/endpoints/users/lists/push.ts
index 899754aaf..3b4a87835 100644
--- a/packages/backend/src/server/api/endpoints/users/lists/push.ts
+++ b/packages/backend/src/server/api/endpoints/users/lists/push.ts
@@ -1,5 +1,5 @@
 import { pushUserToUserList } from "@/services/user-list/push.js";
-import { UserLists, UserListJoinings, Blockings } from "@/models/index.js";
+import { UserLists, UserListJoinings, Blockings, Followings } from "@/models/index.js";
 import define from "../../../define.js";
 import { ApiError } from "../../../error.js";
 import { getUser } from "../../../common/getters.js";
@@ -38,6 +38,13 @@ export const meta = {
 			code: "YOU_HAVE_BEEN_BLOCKED",
 			id: "990232c5-3f9d-4d83-9f3f-ef27b6332a4b",
 		},
+
+		notFollowing: {
+			message:
+				"You cannot push this user because you are not following this user.",
+			code: "NOT_FOLLOWING",
+			id: "0a2e4d73-fe61-41fb-822c-d365ec81ba2a",
+		},
 	},
 } as const;
 
@@ -68,7 +75,7 @@ export default define(meta, paramDef, async (ps, me) => {
 		throw e;
 	});
 
-	// Check blocking
+	// Check blocking and following status
 	if (user.id !== me.id) {
 		const isBlocked = await Blockings.exist({
 			where: {
@@ -76,9 +83,18 @@ export default define(meta, paramDef, async (ps, me) => {
 				blockeeId: me.id,
 			},
 		});
+		const isFollowed = await Followings.exist({
+			where: {
+				followerId: me.id,
+				followeeId: user.id,
+			},
+		});
 		if (isBlocked) {
 			throw new ApiError(meta.errors.youHaveBeenBlocked);
 		}
+		if (!isFollowed) {
+			throw new ApiError(meta.errors.notFollowing);
+		}
 	}
 
 	const exist = await UserListJoinings.exist({
diff --git a/packages/backend/src/server/api/mastodon/helpers/list.ts b/packages/backend/src/server/api/mastodon/helpers/list.ts
index 7ce6d12b5..0fa607b3e 100644
--- a/packages/backend/src/server/api/mastodon/helpers/list.ts
+++ b/packages/backend/src/server/api/mastodon/helpers/list.ts
@@ -1,5 +1,5 @@
 import { ILocalUser, User } from "@/models/entities/user.js";
-import { Blockings, UserListJoinings, UserLists, Users } from "@/models/index.js";
+import { Blockings, Followings, UserListJoinings, UserLists, Users } from "@/models/index.js";
 import { PaginationHelpers } from "@/server/api/mastodon/helpers/pagination.js";
 import { UserList } from "@/models/entities/user-list.js";
 import { pushUserToUserList } from "@/services/user-list/push.js";
@@ -76,7 +76,14 @@ export class ListHelpers {
                         blockeeId: localUser.id,
                     },
                 });
+                const isFollowed = await Followings.exist({
+                    where: {
+                        followeeId: user.id,
+                        followerId: localUser.id,
+                    },
+                });
                 if (isBlocked) throw Error("Can't add users you've been blocked by to list");
+                if (!isFollowed) throw Error("Can't add users you're not following to list");
             }
 
             const exist = await UserListJoinings.exist({
diff --git a/packages/backend/src/services/user-list/push.ts b/packages/backend/src/services/user-list/push.ts
index 7866ca17f..74827b46b 100644
--- a/packages/backend/src/services/user-list/push.ts
+++ b/packages/backend/src/services/user-list/push.ts
@@ -1,9 +1,10 @@
 import { publishUserListStream } from "@/services/stream.js";
 import type { User } from "@/models/entities/user.js";
 import type { UserList } from "@/models/entities/user-list.js";
-import { UserListJoinings, Users } from "@/models/index.js";
+import { Followings, UserListJoinings, Users } from "@/models/index.js";
 import type { UserListJoining } from "@/models/entities/user-list-joining.js";
 import { genId } from "@/misc/gen-id.js";
+import { ApiError } from "@/server/api/error.js";
 
 export async function pushUserToUserList(target: User, list: UserList) {
 	await UserListJoinings.insert({