MRF.ObjectAgePolicy: Check objects alongside Create activities

ObjectAgePolicy only checked Create activites, which still resulted in
some old posts making it to user timelines, even when it was enabled.

This fixes that issue by also checking objects of an updatable type
as defined in `Pleroma.Constants.updatable_object_types`.

lib/pleroma/constants.ex

@@ -43,17 +43,19 @@ defmodule Pleroma.Constants do
     ]
   )
 
-  const(updatable_object_types,
-    do: [
-      "Note",
-      "Question",
-      "Audio",
-      "Video",
-      "Event",
-      "Article",
-      "Page"
-    ]
-  )
+  @updatable_object_types [
+    "Note",
+    "Question",
+    "Audio",
+    "Video",
+    "Event",
+    "Article",
+    "Page"
+  ]
+
+  const(updatable_object_types, do: @updatable_object_types)
+
+  const(object_types, do: @updatable_object_types ++ ["Answer"])
 
   const(actor_types,
     do: [

lib/pleroma/web/activity_pub/mrf/object_age_policy.ex

@@ -11,12 +11,36 @@ defmodule Pleroma.Web.ActivityPub.MRF.ObjectAgePolicy do
   @moduledoc "Filter activities depending on their age"
   @behaviour Pleroma.Web.ActivityPub.MRF.Policy
 
-  defp check_date(%{"object" => %{"published" => published}} = message) do
+  defp update_to_cc(message, to, cc) do
+    message =
+      message
+      |> Map.put("to", to)
+      |> Map.put("cc", cc)
+
+    if Map.has_key?(message, "object") do
+      message
+      |> Kernel.put_in(["object", "to"], to)
+      |> Kernel.put_in(["object", "cc"], cc)
+    else
+      message
+    end
+  end
+
+  defp check_date(%{"object" => %{"published" => _} = object} = activity) do
+    with {:ok, object} <- check_date(object) do
+      activity = activity |> Map.put("object", object)
+      {:ok, activity}
+    else
+      e -> e
+    end
+  end
+
+  defp check_date(%{"published" => published} = object) do
     with %DateTime{} = now <- DateTime.utc_now(),
          {:ok, %DateTime{} = then, _} <- DateTime.from_iso8601(published),
          max_ttl <- Config.get([:mrf_object_age, :threshold]),
          {:ttl, false} <- {:ttl, DateTime.diff(now, then) > max_ttl} do
-      {:ok, message}
+      {:ok, object}
     else
       {:ttl, true} ->
         {:reject, nil}
@@ -47,10 +71,7 @@ defmodule Pleroma.Web.ActivityPub.MRF.ObjectAgePolicy do
 
         message =
           message
-          |> Map.put("to", to)
-          |> Map.put("cc", cc)
-          |> Kernel.put_in(["object", "to"], to)
-          |> Kernel.put_in(["object", "cc"], cc)
+          |> update_to_cc(to, cc)
 
         {:ok, message}
       else
@@ -70,10 +91,7 @@ defmodule Pleroma.Web.ActivityPub.MRF.ObjectAgePolicy do
 
         message =
           message
-          |> Map.put("to", to)
-          |> Map.put("cc", cc)
-          |> Kernel.put_in(["object", "to"], to)
-          |> Kernel.put_in(["object", "cc"], cc)
+          |> update_to_cc(to, cc)
 
         {:ok, message}
       else
@@ -85,11 +103,18 @@ defmodule Pleroma.Web.ActivityPub.MRF.ObjectAgePolicy do
     end
   end
 
-  @impl true
-  def filter(%{"type" => "Create", "object" => %{"published" => _}} = message) do
+  defp maybe_check_reject(message, _actions, false) do
+    {:ok, message}
+  end
+
+  defp maybe_check_reject(message, actions, true) do
+    check_reject(message, actions)
+  end
+
+  defp check(message, allow_reject) do
     with actions <- Config.get([:mrf_object_age, :actions]),
          {:reject, _} <- check_date(message),
-         {:ok, message} <- check_reject(message, actions),
+         {:ok, message} <- maybe_check_reject(message, actions, allow_reject),
          {:ok, message} <- check_delist(message, actions),
          {:ok, message} <- check_strip_followers(message, actions) do
       {:ok, message}
@@ -99,6 +124,17 @@ defmodule Pleroma.Web.ActivityPub.MRF.ObjectAgePolicy do
     end
   end
 
+  @impl true
+  def filter(%{"type" => "Create", "object" => %{"published" => _}} = message) do
+    check(message, true)
+  end
+
+  @impl true
+  def filter(%{"type" => type, "published" => _} = message)
+      when type in Pleroma.Constants.object_types() do
+    check(message, false)
+  end
+
   @impl true
   def filter(message), do: {:ok, message}
 

test/pleroma/web/activity_pub/mrf/object_age_policy_test.exs

@@ -57,6 +57,15 @@ defmodule Pleroma.Web.ActivityPub.MRF.ObjectAgePolicyTest do
       assert match?({:reject, _}, ObjectAgePolicy.filter(data))
     end
 
+    test "it doesn't reject a fetched post" do
+      clear_config([:mrf_object_age, :actions], [:reject])
+
+      data = get_old_message()
+      object = data["object"]
+
+      assert match?({:ok, _}, ObjectAgePolicy.filter(object))
+    end
+
     test "it allows a new post" do
       clear_config([:mrf_object_age, :actions], [:reject])