Transmogrifier: Fetch missing actors for chatmessages.

lib/pleroma/web/activity_pub/object_validator.ex

@@ -11,6 +11,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
 
   alias Pleroma.Object
   alias Pleroma.User
+  alias Pleroma.Web.ActivityPub.ObjectValidators.Types
   alias Pleroma.Web.ActivityPub.ObjectValidators.ChatMessageValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.CreateChatMessageValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.LikeValidator
@@ -67,8 +68,14 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidator do
     |> Map.new(fn {key, val} -> {to_string(key), val} end)
   end
 
+  def fetch_actor(object) do
+    with {:ok, actor} <- Types.ObjectID.cast(object["actor"]) do
+      User.get_or_fetch_by_ap_id(actor)
+    end
+  end
+
   def fetch_actor_and_object(object) do
-    User.get_or_fetch_by_ap_id(object["actor"])
+    fetch_actor(object)
     Object.normalize(object["object"])
     :ok
   end

lib/pleroma/web/activity_pub/object_validators/create_chat_message_validator.ex

@@ -12,6 +12,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.CreateChatMessageValidator do
   alias Pleroma.Web.ActivityPub.ObjectValidators.Types
 
   import Ecto.Changeset
+  import Pleroma.Web.ActivityPub.ObjectValidators.CommonValidations
 
   @primary_key false
 
@@ -42,6 +43,7 @@ defmodule Pleroma.Web.ActivityPub.ObjectValidators.CreateChatMessageValidator do
     cng
     |> validate_required([:id, :actor, :to, :type, :object])
     |> validate_inclusion(:type, ["Create"])
+    |> validate_actor_presence()
     |> validate_recipients_match(meta)
     |> validate_object_nonexistence()
   end

lib/pleroma/web/activity_pub/transmogrifier.ex

@@ -647,10 +647,10 @@ defmodule Pleroma.Web.ActivityPub.Transmogrifier do
         %{"type" => "Create", "object" => %{"type" => "ChatMessage"}} = data,
         _options
       ) do
-    case Pipeline.common_pipeline(data, local: false) do
-      {:ok, activity, _} ->
-        {:ok, activity}
-
+    with {:ok, %User{}} <- ObjectValidator.fetch_actor(data),
+         {:ok, activity, _} <- Pipeline.common_pipeline(data, local: false) do
+      {:ok, activity}
+    else
       e ->
         e
     end