2 files changed, 44 insertions, 2 deletions
diff --git a/lib/pleroma/web/activity_pub/mrf.ex b/lib/pleroma/web/activity_pub/mrf.ex
index 3bf7955f3..10ceef715 100644
--- a/lib/pleroma/web/activity_pub/mrf.ex
+++ b/lib/pleroma/web/activity_pub/mrf.ex
@@ -5,8 +5,8 @@
 defmodule Pleroma.Web.ActivityPub.MRF do
   @callback filter(Map.t()) :: {:ok | :reject, Map.t()}
 
-  def filter(object) do
-    get_policies()
+  def filter(policies, %{} = object) do
+    policies
     |> Enum.reduce({:ok, object}, fn
       policy, {:ok, object} ->
         policy.filter(object)
@@ -16,6 +16,8 @@ defmodule Pleroma.Web.ActivityPub.MRF do
     end)
   end
 
+  def filter(%{} = object), do: get_policies() |> filter(object)
+
   def get_policies do
     Pleroma.Config.get([:instance, :rewrite_policy], []) |> get_policies()
   end
diff --git a/lib/pleroma/web/activity_pub/mrf/subchain_policy.ex b/lib/pleroma/web/activity_pub/mrf/subchain_policy.ex
new file mode 100644
index 000000000..765704389
--- /dev/null
+++ b/lib/pleroma/web/activity_pub/mrf/subchain_policy.ex
@@ -0,0 +1,40 @@
+# 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.SubchainPolicy do
+  alias Pleroma.Config
+  alias Pleroma.Web.ActivityPub.MRF
+
+  require Logger
+
+  @behaviour MRF
+
+  defp lookup_subchain(actor) do
+    with matches <- Config.get([:mrf_subchain, :match_actor]),
+         {match, subchain} <- Enum.find(matches, fn {k, _v} -> String.match?(actor, k) end) do
+      {:ok, match, subchain}
+    else
+      _e -> {:error, :notfound}
+    end
+  end
+
+  @impl true
+  def filter(%{"actor" => actor} = message) do
+    with {:ok, match, subchain} <- lookup_subchain(actor) do
+      Logger.debug(
+        "[SubchainPolicy] Matched #{actor} against #{inspect(match)} with subchain #{
+          inspect(subchain)
+        }"
+      )
+
+      subchain
+      |> MRF.filter(message)
+    else
+      _e -> {:ok, message}
+    end
+  end
+
+  @impl true
+  def filter(message), do: {:ok, message}
+end