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 steal_emoji({shortcode, url}, emoji_dir_path) do
  16     url = Pleroma.Web.MediaProxy.url(url)
  17
  18     with {:ok, %{status: status} = response} when status in 200..299 <- Pleroma.HTTP.get(url) do
  19       size_limit = Config.get([:mrf_steal_emoji, :size_limit], 50_000)
  20
  21       if byte_size(response.body) <= size_limit do
  22         extension =
  23           url
  24           |> URI.parse()
  25           |> Map.get(:path)
  26           |> Path.basename()
  27           |> Path.extname()
  28
  29         file_path = Path.join(emoji_dir_path, shortcode <> (extension || ".png"))
  30
  31         case File.write(file_path, response.body) do
  32           :ok ->
  33             shortcode
  34
  35           e ->
  36             Logger.warn("MRF.StealEmojiPolicy: Failed to write to #{file_path}: #{inspect(e)}")
  37             nil
  38         end
  39       else
  40         Logger.debug(
  41           "MRF.StealEmojiPolicy: :#{shortcode}: at #{url} (#{byte_size(response.body)} B) over size limit (#{
  42             size_limit
  43           } B)"
  44         )
  45
  46         nil
  47       end
  48     else
  49       e ->
  50         Logger.warn("MRF.StealEmojiPolicy: Failed to fetch #{url}: #{inspect(e)}")
  51         nil
  52     end
  53   end
  54
  55   @impl true
  56   def filter(%{"object" => %{"emoji" => foreign_emojis, "actor" => actor}} = message) do
  57     host = URI.parse(actor).host
  58
  59     if host != Pleroma.Web.Endpoint.host() and accept_host?(host) do
  60       installed_emoji = Pleroma.Emoji.get_all() |> Enum.map(fn {k, _} -> k end)
  61
  62       emoji_dir_path =
  63         Config.get(
  64           [:mrf_steal_emoji, :path],
  65           Path.join(Config.get([:instance, :static_dir]), "emoji/stolen")
  66         )
  67
  68       File.mkdir_p(emoji_dir_path)
  69
  70       new_emojis =
  71         foreign_emojis
  72         |> Enum.reject(fn {shortcode, _url} -> shortcode in installed_emoji end)
  73         |> Enum.filter(fn {shortcode, _url} ->
  74           reject_emoji? =
  75             [:mrf_steal_emoji, :rejected_shortcodes]
  76             |> Config.get([])
  77             |> Enum.find(false, fn regex -> String.match?(shortcode, regex) end)
  78
  79           !reject_emoji?
  80         end)
  81         |> Enum.map(&steal_emoji(&1, emoji_dir_path))
  82         |> Enum.filter(& &1)
  83
  84       if !Enum.empty?(new_emojis) do
  85         Logger.info("Stole new emojis: #{inspect(new_emojis)}")
  86         Pleroma.Emoji.reload()
  87       end
  88     end
  89
  90     {:ok, message}
  91   end
  92
  93   def filter(message), do: {:ok, message}
  94
  95   @impl true
  96   @spec config_description :: %{
  97           children: [
  98             %{
  99               description: <<_::272, _::_*256>>,
 100               key: :hosts | :rejected_shortcodes | :size_limit,
 101               suggestions: [any(), ...],
 102               type: {:list, :string} | {:list, :string} | :integer
 103             },
 104             ...
 105           ],
 106           description: <<_::448>>,
 107           key: :mrf_steal_emoji,
 108           label: <<_::80>>,
 109           related_policy: <<_::352>>
 110         }
 111   def config_description do
 112     %{
 113       key: :mrf_steal_emoji,
 114       related_policy: "Pleroma.Web.ActivityPub.MRF.StealEmojiPolicy",
 115       label: "MRF Emojis",
 116       description: "Steals emojis from selected instances when it sees them.",
 117       children: [
 118         %{
 119           key: :hosts,
 120           type: {:list, :string},
 121           description: "List of hosts to steal emojis from",
 122           suggestions: [""]
 123         },
 124         %{
 125           key: :rejected_shortcodes,
 126           type: {:list, :string},
 127           description: "Regex-list of shortcodes to reject",
 128           suggestions: [""]
 129         },
 130         %{
 131           key: :size_limit,
 132           type: :integer,
 133           description: "File size limit (in bytes), checked before an emoji is saved to the disk",
 134           suggestions: ["100000"]
 135         }
 136       ]
 137     }
 138   end
 139
 140   @impl true
 141   def describe do
 142     {:ok, %{}}
 143   end
 144 end