honkoma/lib/pleroma/web/activity_pub/mrf/anti_followbot_policy.ex

86 lines
2.4 KiB
Elixir

# Pleroma: A lightweight social networking server
# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Web.ActivityPub.MRF.AntiFollowbotPolicy do
alias Pleroma.User
@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)
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, actor_type: actor_type}) do
# nickname will be a binary string except when following a relay
nick_score =
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 =
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 + 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)
if score < 0.8 || bot_allowed?(message, actor) do
{:ok, message}
else
{:reject, "[AntiFollowbotPolicy] Scored #{actor_id} as #{score}"}
end
end
@impl true
def filter(message), do: {:ok, message}
@impl true
def describe, do: {:ok, %{}}
end