nextCipher any       // next encryption state
	nextMac    hash.Hash // next MAC algorithm

	level         QUICEncryptionLevel // current QUIC encryption level
	trafficSecret []byte              // current TLS 1.3 traffic secret
}

type permanentError struct {
	err net.Error
}

func (e *permanentError) Error() string   { return e.err.Error() }