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/***************************************************************************
* Copyright (c) 2024 Microsoft Corporation
* Copyright (c) 2025-present Eclipse ThreadX Contributors
*
* This program and the accompanying materials are made available under the
* terms of the MIT License which is available at
* https://opensource.org/licenses/MIT.
*
* SPDX-License-Identifier: MIT
**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** NetX Secure Component */
/** */
/** Transport Layer Security (TLS) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SECURE_SOURCE_CODE
#include "nx_secure_tls.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_tls_send_newsessionticket PORTABLE C */
/* 6.4.3 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function generates a NewSessionTicket message for a TLS Server.*/
/* The message contains data used to generate a PSK that can be used */
/* for session resumption should the same client attempt another */
/* connection within the lifespan of the ticket. */
/* */
/* INPUT */
/* */
/* tls_session TLS control block */
/* send_packet Packet used to send message */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* NX_RAND Generate ticket data */
/* */
/* CALLED BY */
/* */
/* _nx_secure_tls_server_handshake TLS server state machine */
/* */
/**************************************************************************/
#if (NX_SECURE_TLS_TLS_1_3_ENABLED)
UINT _nx_secure_tls_send_newsessionticket(NX_SECURE_TLS_SESSION *tls_session, NX_PACKET *send_packet)
{
UINT status = NX_SUCCESS;
UINT length;
UINT lifetime;
UINT age_add;
UINT nonce;
UINT nonce_len;
UINT ticket_len;
UCHAR *ticket;
UINT extensions_len;
UCHAR *packet_buffer;
/* From RFC 8446:
struct {
uint32 ticket_lifetime;
uint32 ticket_age_add;
opaque ticket_nonce<0..255>;
opaque ticket<1..2^16-1>;
Extension extensions<0..2^16-2>;
} NewSessionTicket;
| 4 | 4 | 1 | <nonce_len> | 2 | <ticket_len> | 2 | <extensions_len> |
| lifetime | age add | nonce_len | nonce | ticket_len | ticket | extensions_len | extensions |
ticket_lifetime: Indicates the lifetime in seconds as a 32-bit
unsigned integer in network byte order from the time of ticket
issuance. Servers MUST NOT use any value greater than
604800 seconds (7 days). The value of zero indicates that the
ticket should be discarded immediately. Clients MUST NOT cache
tickets for longer than 7 days, regardless of the ticket_lifetime,
and MAY delete tickets earlier based on local policy. A server
MAY treat a ticket as valid for a shorter period of time than what
is stated in the ticket_lifetime.
ticket_age_add: A securely generated, random 32-bit value that is
used to obscure the age of the ticket that the client includes in
the "pre_shared_key" extension. The client-side ticket age is
added to this value modulo 2^32 to obtain the value that is
transmitted by the client. The server MUST generate a fresh value
for each ticket it sends.
ticket_nonce: A per-ticket value that is unique across all tickets
issued on this connection.
ticket: The value of the ticket to be used as the PSK identity. The
ticket itself is an opaque label. It MAY be either a database
lookup key or a self-encrypted and self-authenticated value.
extensions: A set of extension values for the ticket. The
"Extension" format is defined in Section 4.2. Clients MUST ignore
unrecognized extensions.
The sole extension currently defined for NewSessionTicket is
"early_data", indicating that the ticket may be used to send 0-RTT
data (Section 4.2.10). It contains the following value:
max_early_data_size: The maximum amount of 0-RTT data that the
client is allowed to send when using this ticket, in bytes. Only
Application Data payload (i.e., plaintext but not padding or the
inner content type byte) is counted. A server receiving more than
max_early_data_size bytes of 0-RTT data SHOULD terminate the
connection with an "unexpected_message" alert. Note that servers
that reject early data due to lack of cryptographic material will
be unable to differentiate padding from content, so clients
SHOULD NOT depend on being able to send large quantities of
padding in early data records.
The PSK associated with the ticket is computed as:
HKDF-Expand-Label(resumption_master_secret,
"resumption", ticket_nonce, Hash.length)
*/
NX_PARAMETER_NOT_USED(tls_session);
if (((ULONG)(send_packet -> nx_packet_data_end) - (ULONG)(send_packet -> nx_packet_append_ptr)) < 13u)
{
/* Packet buffer too small. */
return(NX_SECURE_TLS_PACKET_BUFFER_TOO_SMALL);
}
length = 0;
packet_buffer = send_packet -> nx_packet_append_ptr;
/* First, the ticket lifetime in ms - 604800 is the maximum. */
lifetime = 604800;
packet_buffer[length] = (UCHAR)((lifetime & 0xFF000000) >> 24);
packet_buffer[length + 1] = (UCHAR)((lifetime & 0x00FF0000) >> 16);
packet_buffer[length + 2] = (UCHAR)((lifetime & 0x0000FF00) >> 8);
packet_buffer[length + 3] = (UCHAR) (lifetime & 0x000000FF);
length += 4;
/* The age_add is a cryptographically secure random 32-bit number. */
age_add = (UINT)NX_RAND();
packet_buffer[length] = (UCHAR)((age_add & 0xFF000000) >> 24);
packet_buffer[length + 1] = (UCHAR)((age_add & 0x00FF0000) >> 16);
packet_buffer[length + 2] = (UCHAR)((age_add & 0x0000FF00) >> 8);
packet_buffer[length + 3] = (UCHAR) (age_add & 0x000000FF);
length += 4;
/* Set up the nonce - 4 bytes of random data. */
nonce = (UINT)NX_RAND();
nonce_len = 4;
/* Add in the nonce length. */
packet_buffer[length] = (UCHAR)(nonce_len & 0xFF);
length += 1;
/* Nonces are currently max 32 bits */
packet_buffer[length] = (UCHAR)((nonce & 0xFF000000) >> 24);
packet_buffer[length + 1] = (UCHAR)((nonce & 0x00FF0000) >> 16);
packet_buffer[length + 2] = (UCHAR)((nonce & 0x0000FF00) >> 8);
packet_buffer[length + 3] = (UCHAR) (nonce & 0x000000FF);
length += nonce_len;
/* Now for the ticket ID itself. 16-bit length with the ticket being a label
used as the PSK identity. */
ticket = (UCHAR *)("NewSessionTicket");
ticket_len = sizeof("NewSessionTicket");
if (((ULONG)(send_packet -> nx_packet_data_end) - (ULONG)(send_packet -> nx_packet_append_ptr)) < (17u + ticket_len))
{
/* Packet buffer too small. */
return(NX_SECURE_TLS_PACKET_BUFFER_TOO_SMALL);
}
/* Insert ticket length. */
packet_buffer[length] = (UCHAR)((ticket_len & 0xFF00) >> 8);
packet_buffer[length + 1] = (UCHAR)(ticket_len & 0x00FF);
length += 2;
/* Copy in ticket. */
NX_SECURE_MEMCPY(&packet_buffer[length], ticket, ticket_len); /* Use case of memcpy is verified. */
length += ticket_len;
/* Add in extensions if available. */
extensions_len = 0;
packet_buffer[length] = (UCHAR)((extensions_len & 0xFF00) >> 8);
packet_buffer[length + 1] = (UCHAR) (extensions_len & 0x00FF);
length += 2;
/* Adjust the packet into which we just wrote the finished hash. */
send_packet -> nx_packet_append_ptr = send_packet -> nx_packet_append_ptr + length;
send_packet -> nx_packet_length = send_packet -> nx_packet_length + length;
return(status);
}
#endif
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