Function checkALPN

handshake_client.go:752–765

checkALPN ensure that the server's choice of ALPN protocol is compatible with the protocols that we advertised in the Client Hello.

(clientProtos []string, serverProto string)

// checkALPN ensure that the server's choice of ALPN protocol is compatible with
// the protocols that we advertised in the Client Hello.
func checkALPN(clientProtos []string, serverProto string) error {
	if serverProto == "" {
		return nil
	}
	if len(clientProtos) == 0 {
		return errors.New("tls: server advertised unrequested ALPN extension")
	}
	for _, proto := range clientProtos {
		if proto == serverProto {
			return nil
		}
	}
	return errors.New("tls: server selected unadvertised ALPN protocol")
}

func (hs *clientHandshakeState) readFinished(out []byte) error {
	c := hs.c