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# 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.ObjectAgePolicy do
alias Pleroma.Config
alias Pleroma.User
require Pleroma.Constants
@moduledoc "Filter activities depending on their age"
@behaviour Pleroma.Web.ActivityPub.MRF
defp check_date(%{"object" => %{"published" => published}} = message) do
with %DateTime{} = now <- DateTime.utc_now(),
{:ok, %DateTime{} = then, _} <- DateTime.from_iso8601(published),
max_ttl <- Config.get([:mrf_object_age, :threshold]),
{:ttl, false} <- {:ttl, DateTime.diff(now, then) > max_ttl} do
{:ok, message}
else
{:ttl, true} ->
{:reject, nil}
e ->
{:error, e}
end
end
defp check_reject(message, actions) do
if :reject in actions do
{:reject, nil}
else
{:ok, message}
end
end
defp check_delist(message, actions) do
if :delist in actions do
with %User{} = user <- User.get_cached_by_ap_id(message["actor"]) do
to = List.delete(message["to"], Pleroma.Constants.as_public()) ++ [user.follower_address]
cc = List.delete(message["cc"], user.follower_address) ++ [Pleroma.Constants.as_public()]
message =
message
|> Map.put("to", to)
|> Map.put("cc", cc)
{:ok, message}
else
# Unhandleable error: somebody is messing around, just drop the message.
_e ->
{:reject, nil}
end
else
{:ok, message}
end
end
defp check_strip_followers(message, actions) do
if :strip_followers in actions do
with %User{} = user <- User.get_cached_by_ap_id(message["actor"]) do
to = List.delete(message["to"], user.follower_address)
cc = List.delete(message["cc"], user.follower_address)
message =
message
|> Map.put("to", to)
|> Map.put("cc", cc)
{:ok, message}
else
# Unhandleable error: somebody is messing around, just drop the message.
_e ->
{:reject, nil}
end
else
{:ok, message}
end
end
@impl true
def filter(%{"type" => "Create", "published" => _} = message) do
with actions <- Config.get([:mrf_object_age, :actions]),
{:reject, _} <- check_date(message),
{:ok, message} <- check_reject(message, actions),
{:ok, message} <- check_delist(message, actions),
{:ok, message} <- check_strip_followers(message, actions) do
{:ok, message}
else
# check_date() is allowed to short-circuit the pipeline
e -> e
end
end
@impl true
def filter(message), do: {:ok, message}
@impl true
def describe do
mrf_object_age =
Pleroma.Config.get(:mrf_object_age)
|> Enum.into(%{})
{:ok, %{mrf_object_age: mrf_object_age}}
end
end
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