const unsigned char *p;
    size_t len, remaining;

    dprintf("Called");

    if (statePtr->vcmd == (Tcl_Obj*)NULL) {
	return SSL_CLIENT_HELLO_SUCCESS;
    } else if (ssl == (const SSL *)NULL || arg == (void *)NULL) {
    } else if (ssl == (const SSL *)NULL || arg == NULL) {
	return SSL_CLIENT_HELLO_ERROR;
    }

    /* Get names */
    if (!SSL_client_hello_get0_ext(ssl, TLSEXT_TYPE_server_name, &p, &remaining) || remaining <= 2) {
	*alert = SSL_R_SSLV3_ALERT_ILLEGAL_PARAMETER;
	return SSL_CLIENT_HELLO_ERROR;

    }

    if (model != NULL) {
	int mode;
	/* Get the "model" context */
	chan = Tcl_GetChannel(interp, model, &mode);
	if (chan == (Tcl_Channel) NULL) {
	    Tls_Free((tls_free_type *)statePtr);
	    Tls_Free(statePtr);
	    return TCL_ERROR;
	}

	/*
	 * Make sure to operate on the topmost channel
	 */
	chan = Tcl_GetTopChannel(chan);
	if (Tcl_GetChannelType(chan) != Tls_ChannelType()) {
	    Tcl_AppendResult(interp, "bad channel \"", Tcl_GetChannelName(chan),
		    "\": not a TLS channel", (char *)NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "CHANNEL", "INVALID", (char *)NULL);
	    Tls_Free((tls_free_type *)statePtr);
	    Tls_Free(statePtr);
	    return TCL_ERROR;
	}
	ctx = ((State *)Tcl_GetChannelInstanceData(chan))->ctx;
    } else {
	if ((ctx = CTX_Init(statePtr, server, proto, keyfile, certfile, key, cert, (int)key_len,
		(int)cert_len, CApath, CAfile, ciphers, ciphersuites, level, DHparams)) == NULL) {
	    Tls_Free((tls_free_type *)statePtr);
	    Tls_Free(statePtr);
	    return TCL_ERROR;
	}
    }

    statePtr->ctx = ctx;

    /*

    dprintf("Consuming Tcl channel %s", Tcl_GetChannelName(chan));
    statePtr->self = Tcl_StackChannel(interp, Tls_ChannelType(), statePtr, (TCL_READABLE | TCL_WRITABLE), chan);
    dprintf("Created channel named %s", Tcl_GetChannelName(statePtr->self));
    if (statePtr->self == (Tcl_Channel) NULL) {
	/*
	 * No use of Tcl_EventuallyFree because no possible Tcl_Preserve.
	 */
	Tls_Free((tls_free_type *)statePtr);
	Tls_Free(statePtr);
	return TCL_ERROR;
    }

    Tcl_SetChannelOption(interp, statePtr->self, "-translation", Tcl_DStringValue(&upperChannelTranslation));
    Tcl_SetChannelOption(interp, statePtr->self, "-encoding", Tcl_DStringValue(&upperChannelEncoding));
    Tcl_SetChannelOption(interp, statePtr->self, "-eofchar", Tcl_DStringValue(&upperChannelEOFChar));
    Tcl_SetChannelOption(interp, statePtr->self, "-blocking", Tcl_DStringValue(&upperChannelBlocking));
    Tcl_DStringFree(&upperChannelTranslation);
    Tcl_DStringFree(&upperChannelEncoding);
    Tcl_DStringFree(&upperChannelEOFChar);
    Tcl_DStringFree(&upperChannelBlocking);

    /*
     * SSL Initialization
     */
    statePtr->ssl = SSL_new(statePtr->ctx);
    if (!statePtr->ssl) {
	/* SSL library error */
	Tcl_AppendResult(interp, "couldn't construct ssl session: ", GET_ERR_REASON(), (char *)NULL);
	Tcl_SetErrorCode(interp, "TLS", "IMPORT", "INIT", "FAILED", (char *)NULL);
	Tls_Free((tls_free_type *)statePtr);
	Tls_Free(statePtr);
	return TCL_ERROR;
    }

    /* Set host server name */
    if (servername) {
	/* Sets the server name indication (SNI) in ClientHello extension */
	/* Per RFC 6066, hostname is a ASCII encoded string, though RFC 4366 says UTF-8. */
	if (!SSL_set_tlsext_host_name(statePtr->ssl, servername) && require) {
	    Tcl_AppendResult(interp, "Set SNI extension failed: ", GET_ERR_REASON(), (char *)NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "SNI", "FAILED", (char *)NULL);
	    Tls_Free((tls_free_type *)statePtr);
	    Tls_Free(statePtr);
	    return TCL_ERROR;
	}

	/* Set hostname for peer certificate hostname verification in clients.
	   Don't use SSL_set1_host since it has limitations. */
	if (!SSL_add1_host(statePtr->ssl, servername)) {
	    Tcl_AppendResult(interp, "Set DNS hostname failed: ", GET_ERR_REASON(), (char *)NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "HOSTNAME", "FAILED", (char *)NULL);
	    Tls_Free((tls_free_type *)statePtr);
	    Tls_Free(statePtr);
	    return TCL_ERROR;
	}
    }

    /* Resume session id */
    if (session_id && strlen(session_id) <= SSL_MAX_SID_CTX_LENGTH) {
	/* SSL_set_session() */
	if (!SSL_SESSION_set1_id_context(SSL_get_session(statePtr->ssl),
		(const unsigned char *) session_id, (unsigned int) strlen(session_id))) {
	    Tcl_AppendResult(interp, "Resume session failed: ", GET_ERR_REASON(), (char *)NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "SESSION", "FAILED", (char *)NULL);
	    Tls_Free((tls_free_type *)statePtr);
	    Tls_Free(statePtr);
	    return TCL_ERROR;
	}
    }

    /* Enable Application-Layer Protocol Negotiation. Examples are: http/1.0,
	http/1.1, h2, h3, ftp, imap, pop3, xmpp-client, xmpp-server, mqtt, irc, etc. */
    if (alpn) {
	/* Convert a TCL list into a protocol-list in wire-format */
	unsigned char *protos, *p;
	unsigned int protos_len = 0;
	Tcl_Size cnt, i;
	int j;
	Tcl_Obj **list;

	if (Tcl_ListObjGetElements(interp, alpn, &cnt, &list) != TCL_OK) {
	    Tls_Free((tls_free_type *)statePtr);
	    Tls_Free(statePtr);
	    return TCL_ERROR;
	}

	/* Determine the memory required for the protocol-list */
	for (i = 0; i < cnt; i++) {
	    Tcl_GetStringFromObj(list[i], &len);
	    if (len > 255) {
		Tcl_AppendResult(interp, "ALPN protocol names too long", (char *)NULL);
		Tcl_SetErrorCode(interp, "TLS", "IMPORT", "ALPN", "FAILED", (char *)NULL);
		Tls_Free((tls_free_type *)statePtr);
		Tls_Free(statePtr);
		return TCL_ERROR;
	    }
	    protos_len += 1 + (int) len;
	}

	/* Build the complete protocol-list */
	protos = ckalloc(protos_len);
	/* protocol-lists consist of 8-bit length-prefixed, byte strings */
	for (j = 0, p = protos; j < cnt; j++) {
	    char *str = Tcl_GetStringFromObj(list[j], &len);
	    *p++ = (unsigned char) len;
	    memcpy(p, str, (size_t) len);
	    p += len;
	}

	/* SSL_set_alpn_protos makes a copy of the protocol-list */
	/* Note: This function reverses the return value convention */
	if (SSL_set_alpn_protos(statePtr->ssl, protos, protos_len)) {
	    Tcl_AppendResult(interp, "Set ALPN protocols failed: ", GET_ERR_REASON(), (char *)NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "ALPN", "FAILED", (char *)NULL);
	    Tls_Free((tls_free_type *)statePtr);
	    Tls_Free(statePtr);
	    ckfree(protos);
	    return TCL_ERROR;
	}

	/* Store protocols list */
	statePtr->protos = protos;
	statePtr->protos_len = protos_len;

 *	none
 *
 * Side effects:
 *	Frees all the state
 *
 *-------------------------------------------------------------------
 */
#undef Tls_Free
void
#if TCL_MAJOR_VERSION > 8
Tls_Free(tls_free_type *blockPtr) {
Tls_Free(void *blockPtr)
#else
Tls_Free(char *blockPtr)
#endif
{
    State *statePtr = (State *)blockPtr;

    dprintf("Called");

    Tls_Clean(statePtr);
    ckfree(blockPtr);
}