# File lib/omniauth/strategies/cas.rb, line 29
      def callback_phase
        ticket = request.params['ticket']
        return fail!(:no_ticket, 'No CAS Ticket') unless ticket
        validator = ServiceTicketValidator.new(@configuration, callback_url, ticket)
        @user_info = validator.user_info
        return fail!(:invalid_ticket, 'Invalid CAS Ticket') if @user_info.nil? || @user_info.empty?
        super
      end