From d36fa802d87abcb54a80324148f5cfd35b465335 Mon Sep 17 00:00:00 2001
From: Laura Hausmann <laura@hausmann.dev>
Date: Tue, 29 Oct 2024 15:10:40 +0100
Subject: [PATCH] [backend/federation] Add extra guard clauses to
 ActivityHandlerService

This should be caught by InboxValidationMiddleware, but more checks are always a good idea.
---
 .../Core/Federation/ActivityPub/ActivityHandlerService.cs      | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Iceshrimp.Backend/Core/Federation/ActivityPub/ActivityHandlerService.cs b/Iceshrimp.Backend/Core/Federation/ActivityPub/ActivityHandlerService.cs
index 506b0dfc..a392fec1 100644
--- a/Iceshrimp.Backend/Core/Federation/ActivityPub/ActivityHandlerService.cs
+++ b/Iceshrimp.Backend/Core/Federation/ActivityPub/ActivityHandlerService.cs
@@ -52,6 +52,9 @@ public class ActivityHandlerService(
 			return;
 		}
 
+		if (resolvedActor.IsLocalUser)
+			throw GracefulException.UnprocessableEntity("Refusing to process activity for local user");
+
 		if (new Uri(activity.Actor.Id).Host != new Uri(activity.Id).Host)
 			throw GracefulException
 				.UnprocessableEntity($"Activity identifier ({activity.Id}) host doesn't match actor identifier ({activity.Actor.Id}) host");