+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2021 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) do
- threshold = Pleroma.Config.get([:mrf_hellthread, :threshold])
- recipients = (object["to"] || []) ++ (object["cc"] || [])
+ 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])
- if length(recipients) > threshold do
- {:reject, nil}
+ with {:ok, message} <- reject_message(message, reject_threshold),
+ {:ok, message} <- delist_message(message, delist_threshold) do
+ {:ok, message}
else
- {:ok, object}
+ e -> e
end
end
@impl true
- def filter(object), do: {:ok, object}
+ def filter(message), do: {:ok, message}
+
+ @impl true
+ def describe,
+ do: {:ok, %{mrf_hellthread: Pleroma.Config.get(:mrf_hellthread) |> Enum.into(%{})}}
+
+ @impl true
+ def config_description do
+ %{
+ key: :mrf_hellthread,
+ related_policy: "Pleroma.Web.ActivityPub.MRF.HellthreadPolicy",
+ label: "MRF Hellthread",
+ description: "Block messages with excessive user mentions",
+ children: [
+ %{
+ key: :delist_threshold,
+ type: :integer,
+ description:
+ "Number of mentioned users after which the message gets removed from timelines and" <>
+ "disables notifications. Set to 0 to disable.",
+ suggestions: [10]
+ },
+ %{
+ key: :reject_threshold,
+ type: :integer,
+ description:
+ "Number of mentioned users after which the messaged gets rejected. Set to 0 to disable.",
+ suggestions: [20]
+ }
+ ]
+ }
+ end
end