extend reject MRF to check if originating instance is blocked

[akkoma] / lib / pleroma / web / activity_pub / mrf / anti_followbot_policy.ex

diff --git a/lib/pleroma/web/activity_pub/mrf/anti_followbot_policy.ex b/lib/pleroma/web/activity_pub/mrf/anti_followbot_policy.ex
index 7c6ad582ae9ab6e652d4224931d6451eed461407..627f52168d469429185ec1067fd662a8c2cc02e3 100644 (file)
--- a/lib/pleroma/web/activity_pub/mrf/anti_followbot_policy.ex
+++ b/lib/pleroma/web/activity_pub/mrf/anti_followbot_policy.ex
@@ -1,11 +1,13 @@
 # Pleroma: A lightweight social networking server
-# Copyright © 2019 Pleroma Authors <https://pleroma.social/>
+# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.ActivityPub.MRF.AntiFollowbotPolicy do
   alias Pleroma.User
 
-  @behaviour Pleroma.Web.ActivityPub.MRF
+  @moduledoc "Prevent followbots from following with a bit of heuristic"
+
+  @behaviour Pleroma.Web.ActivityPub.MRF.Policy
 
   # XXX: this should become User.normalize_by_ap_id() or similar, really.
   defp normalize_by_ap_id(%{"id" => id}), do: User.get_cached_by_ap_id(id)
@@ -22,36 +24,62 @@ defmodule Pleroma.Web.ActivityPub.MRF.AntiFollowbotPolicy do
   defp score_displayname("fedibot"), do: 1.0
   defp score_displayname(_), do: 0.0
 
-  defp determine_if_followbot(%User{nickname: nickname, name: displayname}) do
+  defp determine_if_followbot(%User{nickname: nickname, name: displayname, actor_type: actor_type}) do
+    # nickname will be a binary string except when following a relay
     nick_score =
-      nickname
-      |> String.downcase()
-      |> score_nickname()
+      if is_binary(nickname) do
+        nickname
+        |> String.downcase()
+        |> score_nickname()
+      else
+        0.0
+      end
 
+    # displayname will either be a binary string or nil, if a displayname isn't set.
     name_score =
-      displayname
-      |> String.downcase()
-      |> score_displayname()
+      if is_binary(displayname) do
+        displayname
+        |> String.downcase()
+        |> score_displayname()
+      else
+        0.0
+      end
+
+    # actor_type "Service" is a Bot account
+    actor_type_score =
+      if actor_type == "Service" do
+        1.0
+      else
+        0.0
+      end
 
-    nick_score + name_score
+    nick_score + name_score + actor_type_score
   end
 
   defp determine_if_followbot(_), do: 0.0
 
+  defp bot_allowed?(%{"object" => target}, bot_actor) do
+    %User{} = user = normalize_by_ap_id(target)
+
+    User.following?(user, bot_actor)
+  end
+
   @impl true
   def filter(%{"type" => "Follow", "actor" => actor_id} = message) do
     %User{} = actor = normalize_by_ap_id(actor_id)
 
     score = determine_if_followbot(actor)
 
-    # TODO: scan biography data for keywords and score it somehow.
-    if score < 0.8 do
+    if score < 0.8 || bot_allowed?(message, actor) do
       {:ok, message}
     else
-      {:reject, nil}
+      {:reject, "[AntiFollowbotPolicy] Scored #{actor_id} as #{score}"}
     end
   end
 
   @impl true
   def filter(message), do: {:ok, message}
+
+  @impl true
+  def describe, do: {:ok, %{}}
 end