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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_session_sni_extension_parse PORTABLE C */
/* 6.4.3 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function parses an incoming Hello extensions block, looking */
/* for a Server Name Indication (SNI) extension. The SNI extension */
/* (RFC 6066) currently contains only a single DNS Name entry, so only */
/* a single DNS Name is returned. If new RFCs add other name types in */
/* the future, new API will be added. */
/* */
/* This function is intended to be called in a TLS Server callback */
/* as part of processing Hello message extensions. The SNI extension */
/* is only sent by TLS Clients so if a Client receives an SNI */
/* extension it should be ignored. */
/* */
/* INPUT */
/* */
/* tls_session TLS control block */
/* extensions Pointer to received extensions*/
/* num_extensions The number of extensions */
/* received */
/* dns_name Return the name requested by */
/* the client */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* None */
/* */
/* CALLED BY */
/* */
/* Application Code */
/* */
/**************************************************************************/
UINT _nx_secure_tls_session_sni_extension_parse(NX_SECURE_TLS_SESSION *tls_session,
NX_SECURE_TLS_HELLO_EXTENSION *extensions,
UINT num_extensions, NX_SECURE_X509_DNS_NAME *dns_name)
{
UINT i;
const UCHAR *data_ptr;
UCHAR name_type;
USHORT list_length;
UINT offset;
NX_PARAMETER_NOT_USED(tls_session);
/* Loop through the received extensions until we find SNI or hit the end. */
for (i = 0; i < num_extensions; ++i)
{
if (extensions[i].nx_secure_tls_extension_id == NX_SECURE_TLS_EXTENSION_SERVER_NAME_INDICATION)
{
/* Extract the data from the extension. */
/* Server Name Indication Extension structure:
* | 2 | 2 | 1 | 2 | <name length> |
* | Ext Type | list length | name type | name length | Host name string |
*/
/* The generic extension parsing already handled the extension type, so this points to the
list length field. */
data_ptr = extensions[i].nx_secure_tls_extension_data;
/* Extract the list length. */
list_length = (USHORT)((data_ptr[0] << 8) + data_ptr[1]);
offset = 2;
/* Extract the name type. */
name_type = data_ptr[offset];
offset += 1;
/* Extract the name length. */
dns_name -> nx_secure_x509_dns_name_length = (USHORT)((data_ptr[offset] << 8) + data_ptr[offset + 1]);
offset += 2;
/* Check the name type and lengths. */
if (name_type != NX_SECURE_TLS_SNI_NAME_TYPE_DNS ||
list_length > extensions[i].nx_secure_tls_extension_data_length ||
dns_name -> nx_secure_x509_dns_name_length > list_length)
{
return(NX_SECURE_TLS_SNI_EXTENSION_INVALID);
}
/* Make sure we don't copy over the end of the buffer. */
if (dns_name -> nx_secure_x509_dns_name_length > NX_SECURE_X509_DNS_NAME_MAX)
{
dns_name -> nx_secure_x509_dns_name_length = NX_SECURE_X509_DNS_NAME_MAX;
}
/* Name and lengths check out, save off the name data. */
NX_SECURE_MEMCPY(dns_name -> nx_secure_x509_dns_name, &data_ptr[offset], dns_name -> nx_secure_x509_dns_name_length); /* Use case of memcpy is verified. lgtm[cpp/banned-api-usage-required-any] */
/* Success! */
return(NX_SUCCESS);
}
}
/* Searched through all the extensions, did not find SNI. */
return(NX_SECURE_TLS_EXTENSION_NOT_FOUND);
}
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