git.squeep.com Git - akkoma/blob - lib/pleroma/web/activity_pub/mrf/steal_emoji_policy.ex

   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.Web.ActivityPub.MRF.StealEmojiPolicy do
   6   require Logger
   7
   8   alias Pleroma.Config
   9
  10   @moduledoc "Detect new emojis by their shortcode and steals them"
  11   @behaviour Pleroma.Web.ActivityPub.MRF.Policy
  12
  13   defp accept_host?(host), do: host in Config.get([:mrf_steal_emoji, :hosts], [])
  14
  15   defp shortcode_matches?(shortcode, pattern) when is_binary(pattern) do
  16     shortcode == pattern
  17   end
  18
  19   defp shortcode_matches?(shortcode, pattern) do
  20     String.match?(shortcode, pattern)
  21   end
  22
  23   defp steal_emoji({shortcode, url}, emoji_dir_path) do
  24     url = Pleroma.Web.MediaProxy.url(url)
  25
  26     with {:ok, %{status: status} = response} when status in 200..299 <- Pleroma.HTTP.get(url) do
  27       size_limit = Config.get([:mrf_steal_emoji, :size_limit], 50_000)
  28
  29       if byte_size(response.body) <= size_limit do
  30         extension =
  31           url
  32           |> URI.parse()
  33           |> Map.get(:path)
  34           |> Path.basename()
  35           |> Path.extname()
  36
  37         file_path = Path.join(emoji_dir_path, shortcode <> (extension || ".png"))
  38
  39         case File.write(file_path, response.body) do
  40           :ok ->
  41             shortcode
  42
  43           e ->
  44             Logger.warn("MRF.StealEmojiPolicy: Failed to write to #{file_path}: #{inspect(e)}")
  45             nil
  46         end
  47       else
  48         Logger.debug(
  49           "MRF.StealEmojiPolicy: :#{shortcode}: at #{url} (#{byte_size(response.body)} B) over size limit (#{size_limit} B)"
  50         )
  51
  52         nil
  53       end
  54     else
  55       e ->
  56         Logger.warn("MRF.StealEmojiPolicy: Failed to fetch #{url}: #{inspect(e)}")
  57         nil
  58     end
  59   end
  60
  61   @impl true
  62   def filter(%{"object" => %{"emoji" => foreign_emojis, "actor" => actor}} = message) do
  63     host = URI.parse(actor).host
  64
  65     if host != Pleroma.Web.Endpoint.host() and accept_host?(host) do
  66       installed_emoji = Pleroma.Emoji.get_all() |> Enum.map(fn {k, _} -> k end)
  67
  68       emoji_dir_path =
  69         Config.get(
  70           [:mrf_steal_emoji, :path],
  71           Path.join(Config.get([:instance, :static_dir]), "emoji/stolen")
  72         )
  73
  74       File.mkdir_p(emoji_dir_path)
  75
  76       new_emojis =
  77         foreign_emojis
  78         |> Enum.reject(fn {shortcode, _url} -> shortcode in installed_emoji end)
  79         |> Enum.filter(fn {shortcode, _url} ->
  80           reject_emoji? =
  81             [:mrf_steal_emoji, :rejected_shortcodes]
  82             |> Config.get([])
  83             |> Enum.find(false, fn pattern -> shortcode_matches?(shortcode, pattern) end)
  84
  85           !reject_emoji?
  86         end)
  87         |> Enum.map(&steal_emoji(&1, emoji_dir_path))
  88         |> Enum.filter(& &1)
  89
  90       if !Enum.empty?(new_emojis) do
  91         Logger.info("Stole new emojis: #{inspect(new_emojis)}")
  92         Pleroma.Emoji.reload()
  93       end
  94     end
  95
  96     {:ok, message}
  97   end
  98
  99   def filter(message), do: {:ok, message}
 100
 101   @impl true
 102   @spec config_description :: %{
 103           children: [
 104             %{
 105               description: <<_::272, _::_*256>>,
 106               key: :hosts | :rejected_shortcodes | :size_limit,
 107               suggestions: [any(), ...],
 108               type: {:list, :string} | {:list, :string} | :integer
 109             },
 110             ...
 111           ],
 112           description: <<_::448>>,
 113           key: :mrf_steal_emoji,
 114           label: <<_::80>>,
 115           related_policy: <<_::352>>
 116         }
 117   def config_description do
 118     %{
 119       key: :mrf_steal_emoji,
 120       related_policy: "Pleroma.Web.ActivityPub.MRF.StealEmojiPolicy",
 121       label: "MRF Emojis",
 122       description: "Steals emojis from selected instances when it sees them.",
 123       children: [
 124         %{
 125           key: :hosts,
 126           type: {:list, :string},
 127           description: "List of hosts to steal emojis from",
 128           suggestions: [""]
 129         },
 130         %{
 131           key: :rejected_shortcodes,
 132           type: {:list, :string},
 133           description: """
 134             A list of patterns or matches to reject shortcodes with.
 135
 136             Each pattern can be a string or [Regex](https://hexdocs.pm/elixir/Regex.html) in the format of `~r/PATTERN/`.
 137           """,
 138           suggestions: ["foo", ~r/foo/]
 139         },
 140         %{
 141           key: :size_limit,
 142           type: :integer,
 143           description: "File size limit (in bytes), checked before an emoji is saved to the disk",
 144           suggestions: ["100000"]
 145         }
 146       ]
 147     }
 148   end
 149
 150   @impl true
 151   def describe do
 152     {:ok, %{}}
 153   end
 154 end