<code>ERR_reason_error_string()</code>.
	</dd>

	<br>
-->

	<dt>
	  <strong>hello</strong> <em>servername</em>
	</dt>
	<dd>
	  This form of callback is invoked during client hello message processing.
	</dd>

	<br>

	    return 1;
	}
    }
    cmdPtr = Tcl_DuplicateObj(statePtr->callback);

    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("verify", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr,
	Tcl_NewStringObj(Tcl_GetChannelName(statePtr->self), -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewIntObj(depth));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tls_NewX509Obj(interp, cert));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewIntObj(ok));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(errStr ? errStr : "", -1));

    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);

	fclose(fd);
    }
}

/*
 *-------------------------------------------------------------------
 *
 * Password Callback --
 *
 *	Called when a password is needed to unpack RSA and PEM keys.
 *	Evals any bound password script and returns the result as
 *	the password string.
 *-------------------------------------------------------------------
 */
static int

    return -1;
	verify = verify;
}

/*
 *-------------------------------------------------------------------
 *
 * Session Callback for Clients --
 *
 *	Called when a new session ticket has been received. In TLS 1.3
 *	this may be received multiple times after the handshake. For
 *	earlier versions, this will be received during the handshake.
 *
 * Results:
 *	None

    dprintf("Called");

    if (statePtr->callback == (Tcl_Obj*)NULL)
	return 0;

    cmdPtr = Tcl_DuplicateObj(statePtr->callback);

    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("session", -1));

    /* Session id */
    session_id = SSL_SESSION_get0_id_context(session, &len);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(session_id, len));

    /* Session ticket */
    SSL_SESSION_get0_ticket(session, &ticket, &len2);

    servername = SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);
    if (!servername || servername[0] == '\0') {
        return SSL_TLSEXT_ERR_NOACK;
    }

    cmdPtr = Tcl_DuplicateObj(statePtr->callback);

    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("sni", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(servername , -1));

    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);

    Tcl_IncrRefCount(cmdPtr);
    code = Tcl_EvalObjEx(interp, cmdPtr, TCL_EVAL_GLOBAL);

 * Hello Callback for Servers --
 *
 *	Used by server to examine the server name indication (SNI) extension
 *	provided by the client in order to select an appropriate certificate to
 *	present, and make other configuration adjustments relevant to that server
 *	name and its configuration. This includes swapping out the associated
 *	SSL_CTX pointer, modifying the server's list of permitted TLS versions,
*	changing the server's cipher list in response to the client's cipher list, etc.
 *
 * Results:
 *	None
 *
 * Side effects:
 *	Calls callback (if defined)
 *
 * Return codes:
 *	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(const SSL *ssl, int *alert, void *arg) {
    State *statePtr = (State*)arg;
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    int code;
    const char *servername;
    const unsigned char *p;
    size_t len, remaining;

    dprintf("Called");

    if (statePtr->callback == (Tcl_Obj*)NULL)
	return SSL_CLIENT_HELLO_SUCCESS;

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

    /* Extract the length of the supplied list of names. */
    len = (*(p++) << 8);
    len += *(p++);
    if (len + 2 != remaining) {
        return SSL_CLIENT_HELLO_ERROR;
    }
    remaining = len;

    /* The list in practice only has a single element, so we only consider the first one. */
    if (remaining == 0 || *p++ != TLSEXT_NAMETYPE_host_name) {
        return SSL_CLIENT_HELLO_ERROR;
    }
    remaining--;

    /* Now we can finally pull out the byte array with the actual hostname. */
    if (remaining <= 2) {
        return SSL_CLIENT_HELLO_ERROR;
    }
    len = (*(p++) << 8);
    len += *(p++);
    if (len + 2 > remaining) {
        return SSL_CLIENT_HELLO_ERROR;
    }
    remaining = len;
    servername = (const char *)p;

    cmdPtr = Tcl_DuplicateObj(statePtr->callback);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("hello", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(servername, (int)len));

    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);

    Tcl_IncrRefCount(cmdPtr);
    code = Tcl_EvalObjEx(interp, cmdPtr, TCL_EVAL_GLOBAL);
    if (code != TCL_OK) {

	Tcl_AppendResult(interp, "couldn't construct ssl session: ", REASON(), (char *) NULL);
	Tls_Free((char *) statePtr);
	return TCL_ERROR;
    }

    /* Set host server name */
    if (servername) {
	/* Sets the server name indication (SNI) ClientHello extension */
	if (!SSL_set_tlsext_host_name(statePtr->ssl, servername) && require) {
	    Tcl_AppendResult(interp, "setting TLS host name extension failed", (char *) NULL);
            Tls_Free((char *) statePtr);
            return TCL_ERROR;
        }

	/* Configure server host name checks in the SSL client. Set DNS hostname to
	   name for peer certificate checks. SSL_set1_host has limitations. */
	if (!SSL_add1_host(statePtr->ssl, servername)) {
	    Tcl_AppendResult(interp, "setting DNS host name failed", (char *) NULL);
            Tls_Free((char *) 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), session_id, (unsigned int) strlen(session_id))) {
	    Tcl_AppendResult(interp, "Resume session id ", session_id, " failed", (char *) NULL);

#if !defined(NO_TLS1_3) && !defined(OPENSSL_NO_TLS1_3)
    if (proto == TLS_PROTO_TLS1_3) {
	SSL_CTX_set_min_proto_version(ctx, TLS1_3_VERSION);
	SSL_CTX_set_max_proto_version(ctx, TLS1_3_VERSION);
    }
#endif

    /* Force cipher selection order by server */
    if (!isServer) {
	SSL_CTX_set_options(ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
    }

    SSL_CTX_set_app_data(ctx, (void*)interp);	/* remember the interpreter */
    SSL_CTX_set_options(ctx, SSL_OP_ALL);	/* all SSL bug workarounds */
    SSL_CTX_set_options(ctx, off);		/* disable protocol versions */

    X509 *peer;
    Tcl_Obj *objPtr;
    Tcl_Channel chan;
    char *channelName, *ciphers;
    int mode;
    const unsigned char *proto;
    unsigned int len;
    char *peername = NULL;

    dprintf("Called");

    switch (objc) {
	case 2:
	    channelName = Tcl_GetStringFromObj(objv[1], NULL);
	    break;

    if (peer) {
	objPtr = Tls_NewX509Obj(interp, peer);
	if (objc == 2) { X509_free(peer); }
    } else {
	objPtr = Tcl_NewListObj(0, NULL);
    }

    /* Peer cert chain (client only) */
    STACK_OF(X509)* ssl_certs = SSL_get_peer_cert_chain(statePtr->ssl);
    if (!peer && (ssl_certs == NULL || sk_X509_num(ssl_certs) == 0)) {
	return TCL_ERROR;
    }

    /* Peer name from cert */
    if (SSL_get_verify_result(statePtr->ssl) == X509_V_OK) {
	peername = SSL_get0_peername(statePtr->ssl);
    }
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("peername", -1));
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(peername, -1));

    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("sbits", -1));
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewIntObj(SSL_get_cipher_bits(statePtr->ssl, NULL)));

    ciphers = (char*)SSL_get_cipher(statePtr->ssl);
    if ((ciphers != NULL) && (strcmp(ciphers, "(NONE)") != 0)) {
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("cipher", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(SSL_get_cipher(statePtr->ssl), -1));

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

	/* Renegotiation allowed */
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("renegotiation", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(
	    SSL_get_secure_renegotiation_support(ssl) ? "supported" : "not supported", -1));

	/* Report the selected protocol as a result of the ALPN negotiation */
	SSL_get0_alpn_selected(ssl, &proto, &len);
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("alpn", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj((char *)proto, (int)len));

	/* Get security level */

	/* Session info */
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("session_reused", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewIntObj(SSL_session_reused(ssl)));

	/* Session id */
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("session_id", -1));
	session_id = SSL_SESSION_get_id(session, &len);
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(session_id, (int)len));

	/* Session ticket - client only */
	SSL_SESSION_get0_ticket(session, &ticket, &len2);
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("session_ticket", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(ticket, (int) len2));

	/* Resumable session */
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("resumable", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewIntObj(SSL_SESSION_is_resumable(session)));