spc-pleroma/lib/pleroma/web/activity_pub/mrf/steal_emoji_policy.ex

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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.StealEmojiPolicy do
require Logger
alias Pleroma.Config
@moduledoc "Detect new emojis by their shortcode and steals them"
@behaviour Pleroma.Web.ActivityPub.MRF
defp remote_host?(host), do: host != Config.get([Pleroma.Web.Endpoint, :url, :host])
defp accept_host?(host), do: host in Config.get([:mrf_steal_emoji, :hosts], [])
defp steal_emoji({shortcode, url}) do
url = Pleroma.Web.MediaProxy.url(url)
{:ok, response} = Pleroma.HTTP.get(url)
size_limit = Config.get([:mrf_steal_emoji, :size_limit], 50_000)
if byte_size(response.body) <= size_limit do
emoji_dir_path =
Config.get(
[:mrf_steal_emoji, :path],
Path.join(Config.get([:instance, :static_dir]), "emoji/stolen")
)
extension =
url
|> URI.parse()
|> Map.get(:path)
|> Path.basename()
|> Path.extname()
file_path = Path.join([emoji_dir_path, shortcode <> (extension || ".png")])
try do
:ok = File.write(file_path, response.body)
shortcode
rescue
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
rescue
e ->
Logger.warn("MRF.StealEmojiPolicy: Failed to fetch #{url}: #{inspect(e)}")
nil
end
@impl true
def filter(%{"object" => %{"emoji" => foreign_emojis, "actor" => actor}} = message) do
host = URI.parse(actor).host
if remote_host?(host) and accept_host?(host) do
installed_emoji = Pleroma.Emoji.get_all() |> Enum.map(fn {k, _} -> k end)
new_emojis =
foreign_emojis
|> Enum.filter(fn {shortcode, _url} -> shortcode not in installed_emoji end)
|> Enum.filter(fn {shortcode, _url} ->
reject_emoji? =
Config.get([:mrf_steal_emoji, :rejected_shortcodes], [])
|> Enum.find(false, fn regex -> String.match?(shortcode, regex) end)
!reject_emoji?
end)
|> Enum.map(&steal_emoji(&1))
|> 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
def describe do
{:ok, %{}}
end
end