--- /dev/null
+# Pleroma: A lightweight social networking server
+# Copyright © 2019 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
+
+ # 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)
+ defp normalize_by_ap_id(uri) when is_binary(uri), do: User.get_cached_by_ap_id(uri)
+ defp normalize_by_ap_id(_), do: nil
+
+ defp score_nickname("followbot@" <> _), do: 1.0
+ defp score_nickname("federationbot@" <> _), do: 1.0
+ defp score_nickname("federation_bot@" <> _), do: 1.0
+ defp score_nickname(_), do: 0.0
+
+ defp score_displayname("federation bot"), do: 1.0
+ defp score_displayname("federationbot"), do: 1.0
+ defp score_displayname("fedibot"), do: 1.0
+ defp score_displayname(_), do: 0.0
+
+ defp determine_if_followbot(%User{nickname: nickname, name: displayname}) do
+ nick_score =
+ nickname
+ |> String.downcase()
+ |> score_nickname()
+
+ name_score =
+ displayname
+ |> String.downcase()
+ |> score_displayname()
+
+ nick_score + name_score
+ end
+
+ defp determine_if_followbot(_), do: 0.0
+
+ @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
+ {:ok, message}
+ else
+ {:reject, nil}
+ end
+ end
+
+ @impl true
+ def filter(message), do: {:ok, message}
+end