ensure only pickable frontends can be returned

[akkoma] / lib / pleroma / web / plugs / frontend_static.ex

diff --git a/lib/pleroma/web/plugs/frontend_static.ex b/lib/pleroma/web/plugs/frontend_static.ex
index 03fd510431e882ab2c17bcb3cd01560d6dd687b1..41b8ba46b90d659a5ba17069f9a8da6eae87076b 100644 (file)
--- a/lib/pleroma/web/plugs/frontend_static.ex
+++ b/lib/pleroma/web/plugs/frontend_static.ex
@@ -5,19 +5,23 @@
 defmodule Pleroma.Web.Plugs.FrontendStatic do
   require Pleroma.Constants
 
+  @frontend_cookie_name "preferred_frontend"
+
   @moduledoc """
   This is a shim to call `Plug.Static` but with runtime `from` configuration`. It dispatches to the different frontends.
   """
   @behaviour Plug
 
-  @api_routes Pleroma.Web.get_api_routes()
+  defp instance_static_path do
+    Pleroma.Config.get([:instance, :static_dir], "instance/static")
+  end
 
-  def file_path(path, frontend_type \\ :primary) do
-    if configuration = Pleroma.Config.get([:frontends, frontend_type]) do
-      instance_static_path = Pleroma.Config.get([:instance, :static_dir], "instance/static")
+  def file_path(path, frontend_type \\ :primary)
 
+  def file_path(path, frontend_type) when is_atom(frontend_type) do
+    if configuration = Pleroma.Config.get([:frontends, frontend_type]) do
       Path.join([
-        instance_static_path,
+        instance_static_path(),
         "frontends",
         configuration["name"],
         configuration["ref"],
@@ -28,17 +32,29 @@ defmodule Pleroma.Web.Plugs.FrontendStatic do
     end
   end
 
+  def file_path(path, frontend_type) when is_binary(frontend_type) do
+    Path.join([
+      instance_static_path(),
+      "frontends",
+      frontend_type,
+      path
+    ])
+  end
+
   def init(opts) do
     opts
     |> Keyword.put(:from, "__unconfigured_frontend_static_plug")
     |> Plug.Static.init()
     |> Map.put(:frontend_type, opts[:frontend_type])
+    |> Map.put(:if, Keyword.get(opts, :if, true))
   end
 
   def call(conn, opts) do
     with false <- api_route?(conn.path_info),
          false <- invalid_path?(conn.path_info),
-         frontend_type <- Map.get(opts, :frontend_type, :primary),
+         true <- enabled?(opts[:if]),
+         fallback_frontend_type <- Map.get(opts, :frontend_type, :primary),
+         frontend_type <- preferred_or_fallback(conn, fallback_frontend_type),
          path when not is_nil(path) <- file_path("", frontend_type) do
       call_static(conn, opts, path)
     else
@@ -47,6 +63,35 @@ defmodule Pleroma.Web.Plugs.FrontendStatic do
     end
   end
 
+  def preferred_frontend(conn) do
+    %{req_cookies: cookies} =
+      conn
+      |> Plug.Conn.fetch_cookies()
+
+    Map.get(cookies, @frontend_cookie_name)
+  end
+
+  # Only override primary frontend
+  def preferred_or_fallback(conn, :primary) do
+    case preferred_frontend(conn) do
+      nil ->
+        :primary
+
+      frontend ->
+        if Enum.member?(Pleroma.Config.get([:frontends, :pickable], []), frontend) do
+          frontend
+        else
+          :primary
+        end
+    end
+  end
+
+  def preferred_or_fallback(_conn, fallback), do: fallback
+
+  defp enabled?(if_opt) when is_function(if_opt), do: if_opt.()
+  defp enabled?(true), do: true
+  defp enabled?(_), do: false
+
   defp invalid_path?(list) do
     invalid_path?(list, :binary.compile_pattern(["/", "\\", ":", "\0"]))
   end
@@ -55,11 +100,12 @@ defmodule Pleroma.Web.Plugs.FrontendStatic do
   defp invalid_path?([h | t], match), do: String.contains?(h, match) or invalid_path?(t)
   defp invalid_path?([], _match), do: false
 
-  defp api_route?(list) when is_list(list) and length(list) > 0 do
-    List.first(list) in @api_routes
-  end
+  defp api_route?([]), do: false
 
-  defp api_route?(_), do: false
+  defp api_route?([h | t]) do
+    api_routes = Pleroma.Web.Router.get_api_routes()
+    if h in api_routes, do: true, else: api_route?(t)
+  end
 
   defp call_static(conn, opts, from) do
     opts = Map.put(opts, :from, from)