akkoma/lib/pleroma/web/activity_pub/mrf/hellthread_policy.ex
ilja 1f863f0a36
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Fix MRF policies to also work with Update
Objects who got updated would just pass through several of the MRF policies, undoing moderation in some situations.
In the relevant cases we now check not only for Create activities, but also Update activities.

I checked which ones checked explicitly on type Create using `grep '"type" => "Create"' lib/pleroma/web/activity_pub/mrf/*`.

The following from that list have not been changed:
* lib/pleroma/web/activity_pub/mrf/follow_bot_policy.ex
    * Not relevant for moderation
* lib/pleroma/web/activity_pub/mrf/keyword_policy.ex
    * Already had a test for Update
* lib/pleroma/web/activity_pub/mrf/object_age_policy.ex
    * In practice only relevant when fetching old objects (e.g. through Like or Announce). These are always wrapped in a Create.
* lib/pleroma/web/activity_pub/mrf/reject_non_public.ex
    * We don't allow changing scope with Update, so not relevant here
2022-12-08 23:22:05 +01:00

127 lines
3.7 KiB
Elixir

# 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.Policy
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" => type, "object" => %{"type" => object_type}} = message)
when type in ~w{Create Update} and 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(%{})}}
@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