add domain whitelist

steal_emoji_policy.ex

@@ -10,15 +10,23 @@ defmodule Pleroma.Web.ActivityPub.MRF.StealEmojiPolicy do
     length(result) == 1
   end
 
-  defp local_actor(actor) do
-    host = Pleroma.Config.get([Pleroma.Web.Endpoint, :url, :host])
-    prefix = "https://" <> host <> "/"
-    String.starts_with?(actor, prefix)
+  defp is_remote(host) do
+    my_host = Pleroma.Config.get([Pleroma.Web.Endpoint, :url, :host])
+    my_host != host
+  end
+
+  # if whitelist is not defined, everything is "whitelisted"
+  defp is_whitelisted(domain) do
+    whitelist = Pleroma.Config.get([:emoji_stealer, :whitelist])
+
+    whitelist == nil || Enum.member?(whitelist, domain)
   end
 
   @impl true
   def filter(%{"object" => %{"emoji" => foreign_emoji, "actor" => actor}} = object) do
-    unless local_actor(actor) do
+    host = URI.parse(actor).host
+
+    if is_remote(host) && is_whitelisted(host) do
       num_foreign_emoji = Kernel.map_size(foreign_emoji)
 
       if num_foreign_emoji > 0 do