Merge branch 'feature/mention-mrf' into 'develop'

Add MRF MentionPolicy for dropping posts which mention specific actors

See merge request pleroma/pleroma!1439

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

@@ -0,0 +1,24 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Web.ActivityPub.MRF.MentionPolicy do
+  @moduledoc "Block messages which mention a user"
+
+  @behaviour Pleroma.Web.ActivityPub.MRF
+
+  @impl true
+  def filter(%{"type" => "Create"} = message) do
+    reject_actors = Pleroma.Config.get([:mrf_mention, :actors], [])
+    recipients = (message["to"] || []) ++ (message["cc"] || [])
+
+    if Enum.any?(recipients, fn recipient -> Enum.member?(reject_actors, recipient) end) do
+      {:reject, nil}
+    else
+      {:ok, message}
+    end
+  end
+
+  @impl true
+  def filter(message), do: {:ok, message}
+end