Session-based OAuth auth fixes (token expiration check), refactoring, tweaks.

lib/pleroma/helpers/auth_helper.ex

@@ -5,13 +5,21 @@
 defmodule Pleroma.Helpers.AuthHelper do
   alias Pleroma.Web.Plugs.OAuthScopesPlug
 
+  import Plug.Conn
+
   @doc """
   Skips OAuth permissions (scopes) checks, assigns nil `:token`.
   Intended to be used with explicit authentication and only when OAuth token cannot be determined.
   """
   def skip_oauth(conn) do
     conn
-    |> Plug.Conn.assign(:token, nil)
+    |> assign(:token, nil)
     |> OAuthScopesPlug.skip_plug()
   end
+
+  def drop_auth_info(conn) do
+    conn
+    |> assign(:user, nil)
+    |> assign(:token, nil)
+  end
 end