From 2a29b623e999f1199f35f3efca4c999a0d5b370f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Menrath?= <andre.menrath@posteo.de>
Date: Fri, 13 Sep 2024 16:48:16 +0200
Subject: [PATCH] hotfix: announce might also contain an activity

---
 lib/federation/activity_pub/transmogrifier.ex | 62 +++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/lib/federation/activity_pub/transmogrifier.ex b/lib/federation/activity_pub/transmogrifier.ex
index 99c425365..4e2fc9312 100644
--- a/lib/federation/activity_pub/transmogrifier.ex
+++ b/lib/federation/activity_pub/transmogrifier.ex
@@ -379,6 +379,40 @@ defmodule Mobilizon.Federation.ActivityPub.Transmogrifier do
     end
   end
 
+  def handle_incoming(
+        %{
+          "type" => "Announce",
+          "object" => %{
+            "type" => "Delete",
+            "object" =>
+              %{
+                "type" => type
+              } = object
+          },
+          "actor" => _actor,
+          "id" => _id
+        } = data
+      )
+      when type in ["Event", "Note"] do
+    Logger.info("Got an announce with an delete activity.")
+
+    actor_url = Utils.get_actor(data)
+    object_id = Utils.get_url(object)
+
+    case ActivityPubActor.get_or_fetch_actor_by_url(actor_url) do
+      {:error, _err} ->
+        {:error, :unknown_actor}
+
+      {:ok, %Actor{} = actor} ->
+        # If the actor itself is being deleted, no need to check anything other than the object being remote
+        if remote_actor_is_being_deleted(data) do
+          Actions.Delete.delete(actor, actor, false)
+        else
+          handle_group_being_gone(actor, actor_url, object_id)
+        end
+    end
+  end
+
   def handle_incoming(
         %{"type" => "Announce", "object" => object, "actor" => _actor, "id" => _id} = data
       ) do
@@ -1005,6 +1039,30 @@ defmodule Mobilizon.Federation.ActivityPub.Transmogrifier do
   defp fetch_object_optionally_authenticated(url, _),
     do: ActivityPub.fetch_object_from_url(url, force: true)
 
+  # Hotfix for issue #1549: If we receive a share with an Create or Update Activity we add the contained object.
+  defp eventually_create_share(
+         %{
+           "type" => type,
+           "object" =>
+             %{
+               "type" => object_type
+             } = contained_object
+         } = _object,
+         entity,
+         actor_id
+       )
+       when type in ["Create", "Update"] and object_type in ["Event", "Note"] do
+    Logger.info("Maybe adding the contained object of a create/update activity to the share.")
+
+    with object_id <- contained_object |> Utils.get_url(),
+         %Actor{id: object_owner_actor_id} <- Ownable.actor(entity) do
+      {:ok, %Mobilizon.Share{} = _share} =
+        Mobilizon.Share.create(object_id, actor_id, object_owner_actor_id)
+    end
+
+    :ok
+  end
+
   defp eventually_create_share(object, entity, actor_id) do
     with object_id <- object |> Utils.get_url(),
          %Actor{id: object_owner_actor_id} <- Ownable.actor(entity) do
@@ -1161,6 +1219,10 @@ defmodule Mobilizon.Federation.ActivityPub.Transmogrifier do
         Logger.debug("object is really gone")
         {:ok, object}
 
+      {:error, :http_not_found, object} ->
+        Logger.debug("object can not be found any longer")
+        {:ok, object}
+
       {:ok, %{url: url} = object} ->
         if Utils.are_same_origin?(url, Endpoint.url()),
           do: {:ok, object},