akkoma/lib/pleroma/web/activity_pub/mrf/steal_emoji_policy.ex
Hélène 8f140deb8f StealEmojiPolicy: fix String rejected_shortcodes
* rejected_shortcodes is defined as a list of strings in the
  configuration description. As such, database-based configuration was
  led to handle those settings as strings, and not as the actually
  expected type, Regex.
* This caused each message passing through this MRF, if a rejected
  shortcode was set and the emoji did not exist already on the instance,
  to fail federating, as an exception was raised, swiftly caught and
  mostly silenced.
* This commit fixes the issue by introducing new behavior: strings are
  now handled as perfect matches for an emoji shortcode (meaning that if
  the emoji-to-be-pulled's shortcode is in the blacklist, it will be
  rejected), while still supporting Regex types as before.
2022-06-29 20:47:45 +01:00

154 lines
4.4 KiB
Elixir
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

# 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.StealEmojiPolicy do
require Logger
alias Pleroma.Config
@moduledoc "Detect new emojis by their shortcode and steals them"
@behaviour Pleroma.Web.ActivityPub.MRF.Policy
defp accept_host?(host), do: host in Config.get([:mrf_steal_emoji, :hosts], [])
defp shortcode_matches?(shortcode, pattern) when is_binary(pattern) do
shortcode == pattern
end
defp shortcode_matches?(shortcode, pattern) do
String.match?(shortcode, pattern)
end
defp steal_emoji({shortcode, url}, emoji_dir_path) do
url = Pleroma.Web.MediaProxy.url(url)
with {:ok, %{status: status} = response} when status in 200..299 <- Pleroma.HTTP.get(url) do
size_limit = Config.get([:mrf_steal_emoji, :size_limit], 50_000)
if byte_size(response.body) <= size_limit do
extension =
url
|> URI.parse()
|> Map.get(:path)
|> Path.basename()
|> Path.extname()
file_path = Path.join(emoji_dir_path, shortcode <> (extension || ".png"))
case File.write(file_path, response.body) do
:ok ->
shortcode
e ->
Logger.warn("MRF.StealEmojiPolicy: Failed to write to #{file_path}: #{inspect(e)}")
nil
end
else
Logger.debug(
"MRF.StealEmojiPolicy: :#{shortcode}: at #{url} (#{byte_size(response.body)} B) over size limit (#{size_limit} B)"
)
nil
end
else
e ->
Logger.warn("MRF.StealEmojiPolicy: Failed to fetch #{url}: #{inspect(e)}")
nil
end
end
@impl true
def filter(%{"object" => %{"emoji" => foreign_emojis, "actor" => actor}} = message) do
host = URI.parse(actor).host
if host != Pleroma.Web.Endpoint.host() and accept_host?(host) do
installed_emoji = Pleroma.Emoji.get_all() |> Enum.map(fn {k, _} -> k end)
emoji_dir_path =
Config.get(
[:mrf_steal_emoji, :path],
Path.join(Config.get([:instance, :static_dir]), "emoji/stolen")
)
File.mkdir_p(emoji_dir_path)
new_emojis =
foreign_emojis
|> Enum.reject(fn {shortcode, _url} -> shortcode in installed_emoji end)
|> Enum.filter(fn {shortcode, _url} ->
reject_emoji? =
[:mrf_steal_emoji, :rejected_shortcodes]
|> Config.get([])
|> Enum.find(false, fn pattern -> shortcode_matches?(shortcode, pattern) end)
!reject_emoji?
end)
|> Enum.map(&steal_emoji(&1, emoji_dir_path))
|> Enum.filter(& &1)
if !Enum.empty?(new_emojis) do
Logger.info("Stole new emojis: #{inspect(new_emojis)}")
Pleroma.Emoji.reload()
end
end
{:ok, message}
end
def filter(message), do: {:ok, message}
@impl true
@spec config_description :: %{
children: [
%{
description: <<_::272, _::_*256>>,
key: :hosts | :rejected_shortcodes | :size_limit,
suggestions: [any(), ...],
type: {:list, :string} | {:list, :string} | :integer
},
...
],
description: <<_::448>>,
key: :mrf_steal_emoji,
label: <<_::80>>,
related_policy: <<_::352>>
}
def config_description do
%{
key: :mrf_steal_emoji,
related_policy: "Pleroma.Web.ActivityPub.MRF.StealEmojiPolicy",
label: "MRF Emojis",
description: "Steals emojis from selected instances when it sees them.",
children: [
%{
key: :hosts,
type: {:list, :string},
description: "List of hosts to steal emojis from",
suggestions: [""]
},
%{
key: :rejected_shortcodes,
type: {:list, :string},
description: """
A list of patterns or matches to reject shortcodes with.
Each pattern can be a string or [Regex](https://hexdocs.pm/elixir/Regex.html) in the format of `~r/PATTERN/`.
""",
suggestions: ["foo", ~r/foo/]
},
%{
key: :size_limit,
type: :integer,
description: "File size limit (in bytes), checked before an emoji is saved to the disk",
suggestions: ["100000"]
}
]
}
end
@impl true
def describe do
{:ok, %{}}
end
end