break;
    case SSL3_RT_HANDSHAKE:
	type = "Handshake";
	break;
    case SSL3_RT_APPLICATION_DATA:
	type = "App Data";
	break;
#if OPENSSL_VERSION_NUMBER < 0x30000000L
    case DTLS1_RT_HEARTBEAT:
	type = "Heartbeat";
	break;
#endif
    default:
	type = "unknown";
    }

    /* Needs compile time option "enable-ssl-trace". */
    if ((bio = BIO_new(BIO_s_mem())) != NULL) {
	int n;
	SSL_trace(write_p, version, content_type, buf, len, ssl, (void *)bio);
	n = BIO_read(bio, buffer, BIO_pending(bio) < 15000 ? BIO_pending(bio) : 14999);
	n = (n<0) ? 0 : n;
	buffer[n] = 0;
	(void)BIO_flush(bio);
	BIO_free(bio);
   }

    /* Create command to eval */

 * Return codes:
 *	0 = error where session will be immediately removed from the internal cache.
 *	1 = success where app retains session in session cache, and must call SSL_SESSION_free() when done.
 *
 *-------------------------------------------------------------------
 */
static int
SessionCallback(SSL *ssl, SSL_SESSION *session) {
    State *statePtr = (State*)SSL_get_app_data((SSL *)ssl);
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    const unsigned char *ticket;
    const unsigned char *session_id;
    size_t len2;
    unsigned int ulen;

 *	    supplied list and the server configuration. The connection will be aborted.
 *	SSL_TLSEXT_ERR_NOACK: ALPN protocol not selected, e.g., because no ALPN
 *	    protocols are configured for this connection. The connection continues.
 *
 *-------------------------------------------------------------------
 */
static int
ALPNCallback(SSL *ssl, const unsigned char **out, unsigned char *outlen,
	const unsigned char *in, unsigned int inlen, void *arg) {
    State *statePtr = (State*)arg;
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    int code, res;

    dprintf("Called");

    if (ssl == NULL || arg == NULL) {
	return SSL_TLSEXT_ERR_NOACK;
    }

    /* Select protocol */
    if (SSL_select_next_proto((unsigned char **) out, outlen, statePtr->protos, statePtr->protos_len,
	in, inlen) == OPENSSL_NPN_NEGOTIATED) {
	/* Match found */
	res = SSL_TLSEXT_ERR_OK;
    } else {
	/* OPENSSL_NPN_NO_OVERLAP = No overlap, so use first item from client protocol list */
	res = SSL_TLSEXT_ERR_NOACK;
    }

    if (statePtr->vcmd == (Tcl_Obj*)NULL) {
	return res;
    }

    /* Create command to eval */
    cmdPtr = Tcl_DuplicateObj(statePtr->vcmd);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("alpn", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr,
	    Tcl_NewStringObj(Tcl_GetChannelName(statePtr->self), -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj((const char *) *out, -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewBooleanObj(res == SSL_TLSEXT_ERR_OK));

    /* Eval callback command */
    Tcl_IncrRefCount(cmdPtr);
    if ((code = EvalCallback(interp, statePtr, cmdPtr)) > 1) {
	res = SSL_TLSEXT_ERR_NOACK;
    } else if (code == 1) {

 */
static int
SNICallback(const SSL *ssl, int *alert, void *arg) {
    State *statePtr = (State*)arg;
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    int code, res;
    const char *servername = NULL;

    dprintf("Called");

    if (ssl == NULL || arg == NULL) {
	return SSL_TLSEXT_ERR_NOACK;
    }

 *	SSL_CLIENT_HELLO_RETRY: suspend the handshake, and the handshake function will return immediately
 *	SSL_CLIENT_HELLO_ERROR: failure, terminate connection. Set alert to error code.
 *	SSL_CLIENT_HELLO_SUCCESS: success
 *
 *-------------------------------------------------------------------
 */
static int
HelloCallback(SSL *ssl, int *alert, void *arg) {
    State *statePtr = (State*)arg;
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    int code, res;
    const char *servername;
    const unsigned char *p;
    size_t len, remaining;

	/* Get SNI requested server name */
	LAPPEND_STR(interp, objPtr, "servername", SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name), -1);

	/* Get protocol */
	LAPPEND_STR(interp, objPtr, "protocol", SSL_get_version(ssl), -1);

	/* Renegotiation allowed */
	LAPPEND_BOOL(interp, objPtr, "renegotiation_allowed", SSL_get_secure_renegotiation_support((SSL *) ssl));

	/* Get security level */
	LAPPEND_INT(interp, objPtr, "security_level", SSL_get_security_level(ssl));

	/* Session info */
	LAPPEND_BOOL(interp, objPtr, "session_reused", SSL_session_reused(ssl));

    /* Session info */
    session = SSL_get_session(ssl);
    if (session != NULL) {
	const unsigned char *ticket;
	size_t len2;
	unsigned int ulen;
	const unsigned char *session_id, *proto;
	unsigned char buffer[SSL_MAX_MASTER_KEY_LENGTH];

	/* Report the selected protocol as a result of the ALPN negotiation */
	SSL_SESSION_get0_alpn_selected(session, &proto, &len2);
	LAPPEND_STR(interp, objPtr, "alpn", (char *) proto, (Tcl_Size) len2);

	/* Report the selected protocol as a result of the NPN negotiation */
#ifdef USE_NPN

	SSL_SESSION_get0_ticket(session, &ticket, &len2);
	LAPPEND_BARRAY(interp, objPtr, "session_ticket", ticket, (Tcl_Size) len2);

	/* Session ticket lifetime hint (in seconds) */
	LAPPEND_LONG(interp, objPtr, "lifetime", SSL_SESSION_get_ticket_lifetime_hint(session));

	/* Ticket app data */
#if OPENSSL_VERSION_NUMBER < 0x30000000L
	SSL_SESSION_get0_ticket_appdata((SSL_SESSION *) session, &ticket, &len2);
	LAPPEND_BARRAY(interp, objPtr, "ticket_app_data", ticket, (Tcl_Size) len2);
#endif

	/* Get master key */
	len2 = SSL_SESSION_get_master_key(session, buffer, SSL_MAX_MASTER_KEY_LENGTH);
	LAPPEND_BARRAY(interp, objPtr, "master_key", buffer, (Tcl_Size) len2);

	/* Compression id */
	unsigned int id = SSL_SESSION_get_compress_id(session);