lib/pleroma/web/activity_pub/object_validator.ex

@@ -110,6 +110,8 @@ def validate(%{"type" => type} = object, meta)
         "Page" -> ArticleNotePageValidator
       end
 
+    with {:ok, object} <-
+           do_separate_with_history(object, fn object ->
              with {:ok, object} <-
                     object
                     |> validator.cast_and_validate()
@@ -120,6 +122,9 @@ def validate(%{"type" => type} = object, meta)
                tag = (object["tag"] || []) ++ Object.hashtags(%Object{data: object})
                object = Map.put(object, "tag", tag)
 
+               {:ok, object}
+             end
+           end) do
       {:ok, object, meta}
     end
   end
@@ -240,4 +245,54 @@ def fetch_actor_and_object(object) do
     Object.normalize(object["object"], fetch: true)
     :ok
   end
+
+  defp for_each_history_item(
+         %{"type" => "OrderedCollection", "orderedItems" => items} = history,
+         object,
+         fun
+       ) do
+    processed_items =
+      Enum.map(items, fn item ->
+        with item <- Map.put(item, "id", object["id"]),
+             {:ok, item} <- fun.(item) do
+          item
+        else
+          _ -> nil
+        end
+      end)
+
+    if Enum.all?(processed_items, &(not is_nil(&1))) do
+      {:ok, Map.put(history, "orderedItems", processed_items)}
+    else
+      {:error, :invalid_history}
+    end
+  end
+
+  defp for_each_history_item(nil, _object, _fun) do
+    {:ok, nil}
+  end
+
+  defp for_each_history_item(_, _object, _fun) do
+    {:error, :invalid_history}
+  end
+
+  # fun is (object -> {:ok, validated_object_with_string_keys})
+  defp do_separate_with_history(object, fun) do
+    with history <- object["formerRepresentations"],
+         object <- Map.drop(object, ["formerRepresentations"]),
+         {_, {:ok, object}} <- {:main_body, fun.(object)},
+         {_, {:ok, history}} <- {:history_items, for_each_history_item(history, object, fun)} do
+      object =
+        if history do
+          Map.put(object, "formerRepresentations", history)
+        else
+          object
+        end
+
+      {:ok, object}
+    else
+      {:main_body, e} -> e
+      {:history_items, e} -> e
+    end
+  end
 end

test/pleroma/web/activity_pub/object_validators/article_note_page_validator_test.exs

@@ -5,6 +5,7 @@
 defmodule Pleroma.Web.ActivityPub.ObjectValidators.ArticleNotePageValidatorTest do
   use Pleroma.DataCase, async: true
 
+  alias Pleroma.Web.ActivityPub.ObjectValidator
   alias Pleroma.Web.ActivityPub.ObjectValidators.ArticleNotePageValidator
   alias Pleroma.Web.ActivityPub.Utils
 
@@ -149,4 +150,47 @@ test "a misskey MFM status with a _misskey_content field should work and be link
       } = ArticleNotePageValidator.cast_and_validate(note)
     end
   end
+
+  describe "Note with history" do
+    setup do
+      user = insert(:user)
+      {:ok, activity} = Pleroma.Web.CommonAPI.post(user, %{status: "mew mew :dinosaur:"})
+      {:ok, edit} = Pleroma.Web.CommonAPI.update(user, activity, %{status: "edited :blank:"})
+
+      {:ok, %{"object" => external_rep}} =
+        Pleroma.Web.ActivityPub.Transmogrifier.prepare_outgoing(edit.data)
+
+      %{external_rep: external_rep}
+    end
+
+    test "edited note", %{external_rep: external_rep} do
+      assert %{"formerRepresentations" => %{"orderedItems" => [%{"tag" => [_]}]}} = external_rep
+
+      {:ok, validate_res, []} = ObjectValidator.validate(external_rep, [])
+
+      assert %{"formerRepresentations" => %{"orderedItems" => [%{"emoji" => %{"dinosaur" => _}}]}} =
+               validate_res
+    end
+
+    test "edited note, badly-formed formerRepresentations", %{external_rep: external_rep} do
+      external_rep = Map.put(external_rep, "formerRepresentations", %{})
+
+      assert {:error, _} = ObjectValidator.validate(external_rep, [])
+    end
+
+    test "edited note, badly-formed history item", %{external_rep: external_rep} do
+      history_item =
+        Enum.at(external_rep["formerRepresentations"]["orderedItems"], 0)
+        |> Map.put("type", "Foo")
+
+      external_rep =
+        put_in(
+          external_rep,
+          ["formerRepresentations", "orderedItems"],
+          [history_item]
+        )
+
+      assert {:error, _} = ObjectValidator.validate(external_rep, [])
+    end
+  end
 end