# Pleroma: A lightweight social networking server # Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/> # SPDX-License-Identifier: AGPL-3.0-only defmodule Pleroma.Web.ActivityPub.MRF.HellthreadPolicy do alias Pleroma.User require Pleroma.Constants @moduledoc "Block messages with too much mentions (configurable)" @behaviour Pleroma.Web.ActivityPub.MRF defp delist_message(message, threshold) when threshold > 0 do follower_collection = User.get_cached_by_ap_id(message["actor"]).follower_address to = message["to"] || [] cc = message["cc"] || [] follower_collection? = Enum.member?(to ++ cc, follower_collection) message = case get_recipient_count(message) do {:public, recipients} when follower_collection? and recipients > threshold -> message |> Map.put("to", [follower_collection]) |> Map.put("cc", [Pleroma.Constants.as_public()]) {:public, recipients} when recipients > threshold -> message |> Map.put("to", []) |> Map.put("cc", [Pleroma.Constants.as_public()]) _ -> message end {:ok, message} end defp delist_message(message, _threshold), do: {:ok, message} defp reject_message(message, threshold) when threshold > 0 do with {_, recipients} <- get_recipient_count(message) do if recipients > threshold do {:reject, "[HellthreadPolicy] #{recipients} recipients is over the limit of #{threshold}"} else {:ok, message} end end end defp reject_message(message, _threshold), do: {:ok, message} defp get_recipient_count(message) do recipients = (message["to"] || []) ++ (message["cc"] || []) follower_collection = User.get_cached_by_ap_id(message["actor"]).follower_address if Enum.member?(recipients, Pleroma.Constants.as_public()) do recipients = recipients |> List.delete(Pleroma.Constants.as_public()) |> List.delete(follower_collection) {:public, length(recipients)} else recipients = recipients |> List.delete(follower_collection) {:not_public, length(recipients)} end end @impl true def filter(%{"type" => "Create", "object" => %{"type" => object_type}} = message) when object_type in ~w{Note Article} do reject_threshold = Pleroma.Config.get( [:mrf_hellthread, :reject_threshold], Pleroma.Config.get([:mrf_hellthread, :threshold]) ) delist_threshold = Pleroma.Config.get([:mrf_hellthread, :delist_threshold]) with {:ok, message} <- reject_message(message, reject_threshold), {:ok, message} <- delist_message(message, delist_threshold) do {:ok, message} else e -> e end end @impl true def filter(message), do: {:ok, message} @impl true def describe, do: {:ok, %{mrf_hellthread: Pleroma.Config.get(:mrf_hellthread) |> Enum.into(%{})}} end