Function looksLikeUnexpectedTLS

protocol/response.go:148–157

looksLikeUnexpectedTLS returns true if the size passed in resemble the TLS alert message that is returned to a client which sends an invalid ClientHello message.

(size int32)

// the TLS alert message that is returned to a client which sends
// an invalid ClientHello message.
func looksLikeUnexpectedTLS(size int32) bool {
	var sizeBytes [4]byte
	binary.BigEndian.PutUint32(sizeBytes[:], uint32(size))

	if sizeBytes[0] != tlsAlertByte {
		return false
	}
	version := int(sizeBytes[1])<<8 | int(sizeBytes[2])
	return version <= tls.VersionTLS13 && version >= tls.VersionTLS10
}