if http11fallback {
		return "", nil
	}
	return "", fmt.Errorf("tls: client requested unsupported application protocols (%s)", clientProtos)
}

// supportsECDHE returns whether ECDHE key exchanges can be used with this
// pre-TLS 1.3 client.
func supportsECDHE(c *Config, version uint16, supportedCurves []CurveID, supportedPoints []uint8) bool {
	supportsCurve := false
	for _, curve := range supportedCurves {