# File lib/em/protocols/saslauth.rb, line 139
      def validate? username, psw, sysname=nil, realm=nil

        str = [username, psw, sysname, realm].map {|m|
          [(m || "").length, (m || "")]
        }.flatten.pack( "nA*" * 4 )
        send_data str

        d = EM::DefaultDeferrable.new
        @queries.unshift d
        d
      end