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   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.Plugs.FrontendStatic do
   6   require Pleroma.Constants
   7
   8   @frontend_cookie_name "preferred_frontend"
   9
  10   @moduledoc """
  11   This is a shim to call `Plug.Static` but with runtime `from` configuration`. It dispatches to the different frontends.
  12   """
  13   @behaviour Plug
  14
  15   defp instance_static_path do
  16     Pleroma.Config.get([:instance, :static_dir], "instance/static")
  17   end
  18
  19   def file_path(path, frontend_type \\ :primary)
  20
  21   def file_path(path, frontend_type) when is_atom(frontend_type) do
  22     if configuration = Pleroma.Config.get([:frontends, frontend_type]) do
  23       Path.join([
  24         instance_static_path(),
  25         "frontends",
  26         configuration["name"],
  27         configuration["ref"],
  28         path
  29       ])
  30     else
  31       nil
  32     end
  33   end
  34
  35   def file_path(path, frontend_type) when is_binary(frontend_type) do
  36     Path.join([
  37       instance_static_path(),
  38       "frontends",
  39       frontend_type,
  40       path
  41     ])
  42   end
  43
  44   def init(opts) do
  45     opts
  46     |> Keyword.put(:from, "__unconfigured_frontend_static_plug")
  47     |> Plug.Static.init()
  48     |> Map.put(:frontend_type, opts[:frontend_type])
  49     |> Map.put(:if, Keyword.get(opts, :if, true))
  50   end
  51
  52   def call(conn, opts) do
  53     IO.inspect("OPTS: #{inspect(opts)}")
  54     with false <- api_route?(conn.path_info),
  55          false <- invalid_path?(conn.path_info),
  56          true <- enabled?(opts[:if]),
  57          fallback_frontend_type <- Map.get(opts, :frontend_type, :primary),
  58          frontend_type <- preferred_or_fallback(conn, fallback_frontend_type),
  59          path when not is_nil(path) <- file_path("", frontend_type) do
  60       call_static(conn, opts, path)
  61     else
  62       _ ->
  63         conn
  64     end
  65   end
  66
  67   def preferred_frontend(conn) do
  68     %{req_cookies: cookies} =
  69       conn
  70       |> Plug.Conn.fetch_cookies()
  71
  72     Map.get(cookies, @frontend_cookie_name)
  73   end
  74
  75   # Only override primary frontend
  76   def preferred_or_fallback(conn, :primary) do
  77     case preferred_frontend(conn) do
  78       nil ->
  79         :primary
  80
  81       frontend ->
  82         frontend
  83     end
  84   end
  85
  86   def preferred_or_fallback(conn, fallback), do: fallback
  87
  88   defp enabled?(if_opt) when is_function(if_opt), do: if_opt.()
  89   defp enabled?(true), do: true
  90   defp enabled?(_), do: false
  91
  92   defp invalid_path?(list) do
  93     invalid_path?(list, :binary.compile_pattern(["/", "\\", ":", "\0"]))
  94   end
  95
  96   defp invalid_path?([h | _], _match) when h in [".", "..", ""], do: true
  97   defp invalid_path?([h | t], match), do: String.contains?(h, match) or invalid_path?(t)
  98   defp invalid_path?([], _match), do: false
  99
 100   defp api_route?([]), do: false
 101
 102   defp api_route?([h | t]) do
 103     api_routes = Pleroma.Web.Router.get_api_routes()
 104     if h in api_routes, do: true, else: api_route?(t)
 105   end
 106
 107   defp call_static(conn, opts, from) do
 108     opts = Map.put(opts, :from, from)
 109     IO.inspect(opts, label: "opts")
 110     Plug.Static.call(conn, opts)
 111   end
 112 end