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# Pleroma: A lightweight social networking server
# Copyright © 2017-2019 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only
defmodule Pleroma.Web.ActivityPub.MRF.KeywordPolicy do
@moduledoc "Reject or Word-Replace messages with a keyword or regex"
@behaviour Pleroma.Web.ActivityPub.MRF
defp string_matches?(string, _) when not is_binary(string) do
false
end
defp string_matches?(string, pattern) when is_binary(pattern) do
String.contains?(string, pattern)
end
defp string_matches?(string, pattern) do
String.match?(string, pattern)
end
defp check_reject(%{"object" => %{"content" => content, "summary" => summary}} = message) do
if Enum.any?(Pleroma.Config.get([:mrf_keyword, :reject]), fn pattern ->
string_matches?(content, pattern) or string_matches?(summary, pattern)
end) do
{:reject, nil}
else
{:ok, message}
end
end
defp check_ftl_removal(
%{"to" => to, "object" => %{"content" => content, "summary" => summary}} = message
) do
if "https://www.w3.org/ns/activitystreams#Public" in to and
Enum.any?(Pleroma.Config.get([:mrf_keyword, :federated_timeline_removal]), fn pattern ->
string_matches?(content, pattern) or string_matches?(summary, pattern)
end) do
to = List.delete(to, "https://www.w3.org/ns/activitystreams#Public")
cc = ["https://www.w3.org/ns/activitystreams#Public" | message["cc"] || []]
message =
message
|> Map.put("to", to)
|> Map.put("cc", cc)
{:ok, message}
else
{:ok, message}
end
end
defp check_replace(%{"object" => %{"content" => content, "summary" => summary}} = message) do
content =
if is_binary(content) do
content
else
""
end
summary =
if is_binary(summary) do
summary
else
""
end
{content, summary} =
Enum.reduce(
Pleroma.Config.get([:mrf_keyword, :replace]),
{content, summary},
fn {pattern, replacement}, {content_acc, summary_acc} ->
{String.replace(content_acc, pattern, replacement),
String.replace(summary_acc, pattern, replacement)}
end
)
{:ok,
message
|> put_in(["object", "content"], content)
|> put_in(["object", "summary"], summary)}
end
@impl true
def filter(%{"type" => "Create", "object" => %{"content" => _content}} = message) do
with {:ok, message} <- check_reject(message),
{:ok, message} <- check_ftl_removal(message),
{:ok, message} <- check_replace(message) do
{:ok, message}
else
_e ->
{:reject, nil}
end
end
@impl true
def filter(message), do: {:ok, message}
@impl true
def describe do
# This horror is needed to convert regex sigils to strings
mrf_keyword =
Pleroma.Config.get(:mrf_keyword, [])
|> Enum.map(fn {key, value} ->
{key,
Enum.map(value, fn
{pattern, replacement} ->
%{
"pattern" =>
if not is_binary(pattern) do
inspect(pattern)
else
pattern
end,
"replacement" => replacement
}
pattern ->
if not is_binary(pattern) do
inspect(pattern)
else
pattern
end
end)}
end)
|> Enum.into(%{})
{:ok, %{mrf_keyword: mrf_keyword}}
end
end
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