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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"
/* We need to access the supported versions table located in nx_secure_tls_check_protocol_version.c. */
extern const NX_SECURE_VERSIONS_LIST nx_secure_supported_versions_list[];
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_tls_newest_supported_version PORTABLE C */
/* 6.4.3 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* Return the newest currently supported and enabled TLS/DTLS protocol */
/* version. This enables the backward-compatible TLS/DTLS handshake */
/* and forces the upgrade to the latest supported TLS/DTLS version. */
/* */
/* INPUT */
/* */
/* session_ptr TLS session */
/* protocol_version Pointer to version variable */
/* id TLS or DTLS */
/* */
/* OUTPUT */
/* */
/* None */
/* */
/* CALLS */
/* */
/* None */
/* */
/* CALLED BY */
/* */
/* _nx_secure_dtls_send_clienthello Send ClientHello */
/* _nx_secure_tls_process_clienthello Process ClientHello */
/* _nx_secure_tls_send_clienthello Send ClientHello */
/* _nx_secure_tls_protocol_version_get Get current TLS version to use*/
/* */
/**************************************************************************/
VOID _nx_secure_tls_newest_supported_version(NX_SECURE_TLS_SESSION *session_ptr,
USHORT *protocol_version, UINT id)
{
INT i;
NX_PARAMETER_NOT_USED(session_ptr);
#ifndef NX_SECURE_TLS_SERVER_DISABLED
if(session_ptr -> nx_secure_tls_socket_type == NX_SECURE_TLS_SESSION_TYPE_SERVER &&
session_ptr -> nx_secure_tls_protocol_version_override != 0)
{
/* If this is a server and the user has overriden the protocol version,
THAT version is now the higest supported. */
(*protocol_version) = session_ptr -> nx_secure_tls_protocol_version_override;
return;
}
#endif
/* Table is in order of oldest to newest, so walk backward to get
* the newest version we support. */
for (i = (INT)(nx_secure_supported_versions_list[id].nx_secure_versions_list_count - 1); i >= 0; --i)
{
/* If the version is supported, return it. */
if (nx_secure_supported_versions_list[id].nx_secure_versions_list[i].nx_secure_tls_is_supported)
{
(*protocol_version) = nx_secure_supported_versions_list[id].nx_secure_versions_list[i].nx_secure_tls_protocol_version;
return;
}
}
/* If we get here, no versions of TLS have been enabled. Set protocol to 0 to indicate failure. */
(*protocol_version) = 0x0;
return;
}
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_tls_highest_supported_version_negotiate PORTABLE C */
/* 6.4.3 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* Negotiate the highested supported and enabled TLS/DTLS protocol */
/* version, if the protocol version in clientHello is not supported */
/* by the server. */
/* */
/* INPUT */
/* */
/* session_ptr TLS session */
/* protocol_version Pointer to version variable */
/* id TLS or DTLS */
/* */
/* OUTPUT */
/* */
/* None */
/* */
/* CALLS */
/* */
/* None */
/* */
/* CALLED BY */
/* */
/* _nx_secure_dtls_process_clienthello Send ClientHello */
/* _nx_secure_tls_process_clienthello Process ClientHello */
/* */
/**************************************************************************/
void _nx_secure_tls_highest_supported_version_negotiate(NX_SECURE_TLS_SESSION *session_ptr,
USHORT *protocol_version, UINT id)
{
INT i;
USHORT highest_version = 0;
USHORT lowest_version = 0xFF;
USHORT highest_version_not_greater_than_client_version = 0;
NX_PARAMETER_NOT_USED(session_ptr);
#ifndef NX_SECURE_TLS_SERVER_DISABLED
if(session_ptr -> nx_secure_tls_socket_type == NX_SECURE_TLS_SESSION_TYPE_SERVER &&
session_ptr -> nx_secure_tls_negotiated_highest_protocol_version != 0)
{
/* If this is a server and the user has the negotiated highest version,
return it directly. */
(*protocol_version) = session_ptr -> nx_secure_tls_negotiated_highest_protocol_version;
return;
}
#endif
/* Find the highest and the lowest supported server version. */
for (i = (INT)(nx_secure_supported_versions_list[id].nx_secure_versions_list_count - 1); i >= 0; --i)
{
/* If the version is supported, return it. */
if (nx_secure_supported_versions_list[id].nx_secure_versions_list[i].nx_secure_tls_is_supported)
{
if (highest_version < nx_secure_supported_versions_list[id].nx_secure_versions_list[i].nx_secure_tls_protocol_version)
{
highest_version = nx_secure_supported_versions_list[id].nx_secure_versions_list[i].nx_secure_tls_protocol_version;
}
if (lowest_version > nx_secure_supported_versions_list[id].nx_secure_versions_list[i].nx_secure_tls_protocol_version)
{
lowest_version = nx_secure_supported_versions_list[id].nx_secure_versions_list[i].nx_secure_tls_protocol_version;
}
if (!highest_version_not_greater_than_client_version &&
(*protocol_version) >= nx_secure_supported_versions_list[id].nx_secure_versions_list[i].nx_secure_tls_protocol_version)
{
highest_version_not_greater_than_client_version = nx_secure_supported_versions_list[id].nx_secure_versions_list[i].nx_secure_tls_protocol_version;
}
}
}
/* No versions of TLS have been enabled. Set protocol to 0 to indicate failure. */
if (highest_version == 0)
{
(*protocol_version) = 0;
session_ptr -> nx_secure_tls_negotiated_highest_protocol_version = 0;
return;
}
/* According to RFC 5246 E.1,
if protocol_version > highest_version, set protocol_version to highest_version to indicate to send "server_hello" with highest_version;
if lowest_version < protocol_version < highest_version, set protocol_version to the highest server version not greater than protocol_version;
if protocol_version < lowest_version, set protocol_version to 0 to indicate to send a "protocol_version" alert message.
*/
if ((*protocol_version) > highest_version)
{
(*protocol_version) = highest_version;
}
else
{
if ((*protocol_version) < highest_version && (*protocol_version) > lowest_version)
{
(*protocol_version) = highest_version_not_greater_than_client_version;
}
else
{
(*protocol_version) = 0;
}
}
session_ptr -> nx_secure_tls_negotiated_highest_protocol_version = (*protocol_version);
return;
}
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