From 03e14e759db47633cce320285d93d8c1f3bde65c Mon Sep 17 00:00:00 2001
From: "Haelwenn (lanodan) Monnier" <contact@hacktivis.me>
Date: Fri, 24 Mar 2023 09:08:39 +0100
Subject: [PATCH] MRF: Add filtering against AP id

---
 changelog.d/mrf-id_filter.add              | 1 +
 lib/pleroma/web/activity_pub/mrf.ex        | 8 ++++++++
 lib/pleroma/web/activity_pub/mrf/policy.ex | 3 ++-
 3 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 changelog.d/mrf-id_filter.add

diff --git a/changelog.d/mrf-id_filter.add b/changelog.d/mrf-id_filter.add
new file mode 100644
index 000000000..f556f9bc4
--- /dev/null
+++ b/changelog.d/mrf-id_filter.add
@@ -0,0 +1 @@
+Add `id_filter` to MRF to filter URLs and their domain prior to fetching
\ No newline at end of file
diff --git a/lib/pleroma/web/activity_pub/mrf.ex b/lib/pleroma/web/activity_pub/mrf.ex
index bc418d908..51ab476b7 100644
--- a/lib/pleroma/web/activity_pub/mrf.ex
+++ b/lib/pleroma/web/activity_pub/mrf.ex
@@ -108,6 +108,14 @@ defmodule Pleroma.Web.ActivityPub.MRF do
 
   def filter(%{} = object), do: get_policies() |> filter(object)
 
+  def id_filter(policies, id) when is_binary(id) do
+    policies
+    |> Enum.filter(&function_exported?(&1, :id_filter, 1))
+    |> Enum.all?(& &1.id_filter(id))
+  end
+
+  def id_filter(id) when is_binary(id), do: get_policies() |> id_filter(id)
+
   @impl true
   def pipeline_filter(%{} = message, meta) do
     object = meta[:object_data]
diff --git a/lib/pleroma/web/activity_pub/mrf/policy.ex b/lib/pleroma/web/activity_pub/mrf/policy.ex
index 54ca4b735..08bcac08a 100644
--- a/lib/pleroma/web/activity_pub/mrf/policy.ex
+++ b/lib/pleroma/web/activity_pub/mrf/policy.ex
@@ -4,6 +4,7 @@
 
 defmodule Pleroma.Web.ActivityPub.MRF.Policy do
   @callback filter(Pleroma.Activity.t()) :: {:ok | :reject, Pleroma.Activity.t()}
+  @callback id_filter(String.t()) :: boolean()
   @callback describe() :: {:ok | :error, map()}
   @callback config_description() :: %{
               optional(:children) => [map()],
@@ -13,5 +14,5 @@ defmodule Pleroma.Web.ActivityPub.MRF.Policy do
               description: String.t()
             }
   @callback history_awareness() :: :auto | :manual
-  @optional_callbacks config_description: 0, history_awareness: 0
+  @optional_callbacks config_description: 0, history_awareness: 0, id_filter: 1
 end