From 3411bb819f329936dd0f67888249ee859b824db0 Mon Sep 17 00:00:00 2001
From: Tusooa Zhu <tusooa@kazv.moe>
Date: Sun, 3 Jul 2022 20:19:50 -0400
Subject: [PATCH] Validate object data for incoming Update activities

In Create validator we do not validate the object data,
but that is because the object itself will go through the
pipeline again, which is not the case for Update. Thus,
we added validation for objects in Update activities.
---
 .../web/activity_pub/object_validator.ex      |  7 +++-
 .../update_handling_test.exs                  | 38 +++++++++++++++++++
 2 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/lib/pleroma/web/activity_pub/object_validator.ex b/lib/pleroma/web/activity_pub/object_validator.ex
index b904d0c2f..1d4bcc863 100644
--- a/lib/pleroma/web/activity_pub/object_validator.ex
+++ b/lib/pleroma/web/activity_pub/object_validator.ex
@@ -135,8 +135,8 @@ def validate(
       )
       when objtype in ~w[Question Answer Audio Video Event Article Note Page] do
     with {_, false} <- {:local, Access.get(meta, :local, false)},
-         {:ok, object_data} <- cast_and_apply(object),
-         meta = Keyword.put(meta, :object_data, object_data |> stringify_keys),
+         {_, {:ok, object_data, _}} <- {:object_validation, validate(object, meta)},
+         meta = Keyword.put(meta, :object_data, object_data),
          {:ok, update_activity} <-
            update_activity
            |> UpdateValidator.cast_and_validate()
@@ -152,6 +152,9 @@ def validate(
           object = stringify_keys(object)
           {:ok, object, meta}
         end
+
+      {:object_validation, e} ->
+        e
     end
   end
 
diff --git a/test/pleroma/web/activity_pub/object_validators/update_handling_test.exs b/test/pleroma/web/activity_pub/object_validators/update_handling_test.exs
index 997276bcd..a74ee2416 100644
--- a/test/pleroma/web/activity_pub/object_validators/update_handling_test.exs
+++ b/test/pleroma/web/activity_pub/object_validators/update_handling_test.exs
@@ -127,4 +127,42 @@ test "returns object_data in meta for a remote Update" do
       assert meta[:object_data]
     end
   end
+
+  describe "update 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, external_rep} = Pleroma.Web.ActivityPub.Transmogrifier.prepare_outgoing(edit.data)
+      %{external_rep: external_rep}
+    end
+
+    test "edited note", %{external_rep: external_rep} do
+      {:ok, _validate_res, meta} = ObjectValidator.validate(external_rep, [])
+
+      assert %{"formerRepresentations" => %{"orderedItems" => [%{"emoji" => %{"dinosaur" => _}}]}} =
+               meta[:object_data]
+    end
+
+    test "edited note, badly-formed formerRepresentations", %{external_rep: external_rep} do
+      external_rep = put_in(external_rep, ["object", "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["object"]["formerRepresentations"]["orderedItems"], 0)
+        |> Map.put("type", "Foo")
+
+      external_rep =
+        put_in(
+          external_rep,
+          ["object", "formerRepresentations", "orderedItems"],
+          [history_item]
+        )
+
+      assert {:error, _} = ObjectValidator.validate(external_rep, [])
+    end
+  end
 end