char *model		        = NULL;
    char *servername	        = NULL;	/* hostname for Server Name Indication */
    const unsigned char *session_id = NULL;
    Tcl_Obj *alpn		= NULL;
    int ssl2 = 0, ssl3 = 0;
    int tls1 = 1, tls1_1 = 1, tls1_2 = 1, tls1_3 = 1;
    int proto = 0, level = -1;
    int verify = 0, require = 0, request = 1, post_handshake = 0;

    dprintf("Called");

#if OPENSSL_VERSION_NUMBER < 0x10100000L && !defined(OPENSSL_NO_SSL2) && !defined(NO_SSL2) && defined(NO_SSL3) && defined(NO_TLS1) && defined(NO_TLS1_1) && defined(NO_TLS1_2) && defined(NO_TLS1_3)
    ssl2 = 1;
#endif
#if !defined(OPENSSL_NO_SSL3) && !defined(NO_SSL3) && defined(NO_SSL2) && defined(NO_TLS1) && defined(NO_TLS1_1) && defined(NO_TLS1_2) && defined(NO_TLS1_3)

	OPTSTR("-ciphers", ciphers);
	OPTSTR("-ciphersuites", ciphersuites);
	OPTOBJ("-command", script);
	OPTSTR("-dhparams", DHparams);
	OPTSTR("-keyfile", keyfile);
	OPTSTR("-model", model);
	OPTOBJ("-password", password);
	OPTBOOL("-post_handshake", post_handshake);
	OPTBOOL("-require", require);
	OPTBOOL("-request", request);
	OPTINT("-securitylevel", level);
	OPTBOOL("-server", server);
	OPTSTR("-servername", servername);
	OPTSTR("-session_id", session_id);
	OPTOBJ("-alpn", alpn);

	OPTBAD("option", "-alpn, -cadir, -cafile, -cert, -certfile, -cipher, -ciphersuites, -command, -dhparams, -key, -keyfile, -model, -password, -require, -request, -securitylevel, -server, -servername, -session_id, -ssl2, -ssl3, -tls1, -tls1.1, -tls1.2, or -tls1.3");

	return TCL_ERROR;
    }
    if (request)	    verify |= SSL_VERIFY_CLIENT_ONCE | SSL_VERIFY_PEER;
    if (request && require) verify |= SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
    if (request && post_handshake)  verify |= SSL_VERIFY_POST_HANDSHAKE;
    if (verify == 0)	verify = SSL_VERIFY_NONE;

    proto |= (ssl2 ? TLS_PROTO_SSL2 : 0);
    proto |= (ssl3 ? TLS_PROTO_SSL3 : 0);
    proto |= (tls1 ? TLS_PROTO_TLS1 : 0);
    proto |= (tls1_1 ? TLS_PROTO_TLS1_1 : 0);
    proto |= (tls1_2 ? TLS_PROTO_TLS1_2 : 0);

    if (server) {
	/* Server callbacks */
	SSL_CTX_set_alpn_select_cb(statePtr->ctx, ALPNCallback, (void *)statePtr);
	SSL_CTX_set_tlsext_servername_arg(statePtr->ctx, (void *)statePtr);
	SSL_CTX_set_tlsext_servername_callback(statePtr->ctx, SNICallback);
	SSL_CTX_set_client_hello_cb(statePtr->ctx, HelloCallback, (void *)statePtr);

	/* Enable server to send cert request after handshake (TLS 1.3 only) */
	if (request && post_handshake) {
	    SSL_verify_client_post_handshake(statePtr->ssl);
	}

	statePtr->flags |= TLS_TCL_SERVER;
	SSL_set_accept_state(statePtr->ssl);
    } else {
	/* Session caching */
	SSL_CTX_set_session_cache_mode(statePtr->ctx, SSL_SESS_CACHE_CLIENT | SSL_SESS_CACHE_NO_INTERNAL_STORE);
	SSL_CTX_sess_set_new_cb(statePtr->ctx, SessionCallback);

	/* Enable post handshake Authentication extension. TLS 1.3 only, not http/2. */
	if (request && post_handshake) {
	    SSL_set_post_handshake_auth(statePtr->ssl, 1);
	}

	SSL_set_connect_state(statePtr->ssl);
    }
    SSL_set_bio(statePtr->ssl, statePtr->p_bio, statePtr->p_bio);
    BIO_set_ssl(statePtr->bio, statePtr->ssl, BIO_NOCLOSE);

    /*