From 39214431f4b694a098f6417309af1ed9c857a2f1 Mon Sep 17 00:00:00 2001
From: Hazel K <acomputerdog@gmail.com>
Date: Mon, 7 Oct 2024 11:45:58 -0400
Subject: [PATCH] check for host

---
 .../backend/src/misc/is-system-account.ts     |  9 ++++-
 .../test/unit/misc/is-system-account.ts       | 37 ++++++++++++-------
 2 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/packages/backend/src/misc/is-system-account.ts b/packages/backend/src/misc/is-system-account.ts
index 0b699944b3..a34882f494 100644
--- a/packages/backend/src/misc/is-system-account.ts
+++ b/packages/backend/src/misc/is-system-account.ts
@@ -3,9 +3,14 @@
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
+interface UserLike {
+	readonly username: string;
+	readonly host: string | null;
+}
+
 /**
  * Checks if the given user represents a system account, such as instance.actor.
  */
-export function isSystemAccount(user: { readonly username: string }): boolean {
-	return user.username.includes('.');
+export function isSystemAccount(user: UserLike): boolean {
+	return user.host == null && user.username.includes('.');
 }
diff --git a/packages/backend/test/unit/misc/is-system-account.ts b/packages/backend/test/unit/misc/is-system-account.ts
index 045fe04477..d0ab152630 100644
--- a/packages/backend/test/unit/misc/is-system-account.ts
+++ b/packages/backend/test/unit/misc/is-system-account.ts
@@ -7,30 +7,41 @@ import { isSystemAccount } from '@/misc/is-system-account.js';
 
 describe(isSystemAccount, () => {
 	it('should return true for instance.actor', () => {
-		expect(isSystemAccount({ username: 'instance.actor' })).toBeTruthy();
+		expect(isSystemAccount({ username: 'instance.actor', host: null })).toBeTruthy();
 	});
 
 	it('should return true for relay.actor', () => {
-		expect(isSystemAccount({ username: 'relay.actor' })).toBeTruthy();
+		expect(isSystemAccount({ username: 'relay.actor', host: null })).toBeTruthy();
 	});
 
 	it('should return true for any username with a dot', () => {
-		expect(isSystemAccount({ username: 'some.user' })).toBeTruthy();
-		expect(isSystemAccount({ username: 'some.' })).toBeTruthy();
-		expect(isSystemAccount({ username: '.user' })).toBeTruthy();
-		expect(isSystemAccount({ username: '.' })).toBeTruthy();
+		expect(isSystemAccount({ username: 'some.user', host: null })).toBeTruthy();
+		expect(isSystemAccount({ username: 'some.', host: null })).toBeTruthy();
+		expect(isSystemAccount({ username: '.user', host: null })).toBeTruthy();
+		expect(isSystemAccount({ username: '.', host: null })).toBeTruthy();
 	});
 
 	it('should return true for usernames with multiple dots', () => {
-		expect(isSystemAccount({ username: 'some.user.account' })).toBeTruthy();
-		expect(isSystemAccount({ username: '..' })).toBeTruthy();
+		expect(isSystemAccount({ username: 'some.user.account', host: null })).toBeTruthy();
+		expect(isSystemAccount({ username: '..', host: null })).toBeTruthy();
 	});
 
 	it('should return false for usernames without a dot', () => {
-		expect(isSystemAccount({ username: 'instance_actor' })).toBeFalsy();
-		expect(isSystemAccount({ username: 'instanceactor' })).toBeFalsy();
-		expect(isSystemAccount({ username: 'relay_actor' })).toBeFalsy();
-		expect(isSystemAccount({ username: 'relayactor' })).toBeFalsy();
-		expect(isSystemAccount({ username: '' })).toBeFalsy();
+		expect(isSystemAccount({ username: 'instance_actor', host: null })).toBeFalsy();
+		expect(isSystemAccount({ username: 'instanceactor', host: null })).toBeFalsy();
+		expect(isSystemAccount({ username: 'relay_actor', host: null })).toBeFalsy();
+		expect(isSystemAccount({ username: 'relayactor', host: null })).toBeFalsy();
+		expect(isSystemAccount({ username: '', host: null })).toBeFalsy();
+	});
+
+	it('should return false for users from another instance', () => {
+		expect(isSystemAccount({ username: 'instance.actor', host: 'example.com' })).toBeFalsy();
+		expect(isSystemAccount({ username: 'relay.actor', host: 'example.com' })).toBeFalsy();
+		expect(isSystemAccount({ username: 'some.user', host: 'example.com' })).toBeFalsy();
+		expect(isSystemAccount({ username: 'some.', host: 'example.com' })).toBeFalsy();
+		expect(isSystemAccount({ username: '.user', host: 'example.com' })).toBeFalsy();
+		expect(isSystemAccount({ username: '.', host: 'example.com' })).toBeFalsy();
+		expect(isSystemAccount({ username: 'some.user.account', host: 'example.com' })).toBeFalsy();
+		expect(isSystemAccount({ username: '..', host: 'example.com' })).toBeFalsy();
 	});
 });