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/**************************************************************************/
/* */
/* Copyright (c) Microsoft Corporation. All rights reserved. */
/* */
/* This software is licensed under the Microsoft Software License */
/* Terms for Microsoft Azure RTOS. Full text of the license can be */
/* found in the LICENSE file at https://aka.ms/AzureRTOS_EULA */
/* and in the root directory of this software. */
/* */
/**************************************************************************/
/**************************************************************************/
/**************************************************************************/
/** */
/** NetX Secure Component */
/** */
/** Transport Layer Security (TLS) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SECURE_SOURCE_CODE
#include "nx_secure_tls.h"
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_tls_psk_find PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function finds a pre-shared key (PSK) in a TLS session for use */
/* with a PSK ciphersuite. The PSK is found using an "identity hint" */
/* that should match a field in the PSK structure in the TLS session. */
/* */
/* INPUT */
/* */
/* tls_session Pointer to TLS Session */
/* psk_data Pointer to PSK data */
/* psk_length Length of PSK data */
/* psk_identity_hint PSK identity hint data */
/* identity_length Length of identity data */
/* psk_store_index Index of found PSK in store */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* tx_mutex_get Get protection mutex */
/* tx_mutex_put Put protection mutex */
/* */
/* CALLED BY */
/* */
/* _nx_secure_tls_generate_premaster_secret */
/* Generate the shared secret */
/* used to generate keys later */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 Timothy Stapko Initial Version 6.0 */
/* 09-30-2020 Timothy Stapko Modified comment(s), */
/* resulting in version 6.1 */
/* */
/**************************************************************************/
#if defined(NX_SECURE_ENABLE_PSK_CIPHERSUITES) || defined(NX_SECURE_ENABLE_ECJPAKE_CIPHERSUITE)
UINT _nx_secure_tls_psk_find(NX_SECURE_TLS_SESSION *tls_session, UCHAR **psk_data, UINT *psk_length,
UCHAR *psk_identity_hint, UINT identity_length, UINT *psk_store_index)
{
UINT psk_list_size;
UINT compare_val;
UINT i;
/* Get the protection. */
tx_mutex_get(&_nx_secure_tls_protection, TX_WAIT_FOREVER);
psk_list_size = tls_session -> nx_secure_tls_credentials.nx_secure_tls_psk_count;
if ((psk_identity_hint[0] == 0) && (psk_list_size > 0))
{
/* No hint from server. Return the first associated PSK. */
*psk_data = tls_session -> nx_secure_tls_credentials.nx_secure_tls_psk_store[0].nx_secure_tls_psk_data;
*psk_length = tls_session -> nx_secure_tls_credentials.nx_secure_tls_psk_store[0].nx_secure_tls_psk_data_size;
if(psk_store_index != NX_NULL)
{
*psk_store_index = 0;
}
/* Release the protection. */
tx_mutex_put(&_nx_secure_tls_protection);
return(NX_SUCCESS);
}
/* Loop through all PSKs, looking for a matching identity string. */
for (i = 0; i < psk_list_size; ++i)
{
/* Save off the PSK and its length. */
compare_val = (UINT)NX_SECURE_MEMCMP(tls_session -> nx_secure_tls_credentials.nx_secure_tls_psk_store[i].nx_secure_tls_psk_id_hint, psk_identity_hint, identity_length);
/* See if the identity matched, and the length is the same (without the length, we could have a
matching prefix which could be a possible attack vector... */
if (compare_val == 0 && identity_length == tls_session -> nx_secure_tls_credentials.nx_secure_tls_psk_store[i].nx_secure_tls_psk_id_hint_size)
{
/* Found a matching identity, return the associated PSK. */
*psk_data = tls_session -> nx_secure_tls_credentials.nx_secure_tls_psk_store[i].nx_secure_tls_psk_data;
*psk_length = tls_session -> nx_secure_tls_credentials.nx_secure_tls_psk_store[i].nx_secure_tls_psk_data_size;
if(psk_store_index != NX_NULL)
{
*psk_store_index = i;
}
/* Release the protection. */
tx_mutex_put(&_nx_secure_tls_protection);
return(NX_SUCCESS);
}
}
/* Release the protection. */
tx_mutex_put(&_nx_secure_tls_protection);
return(NX_SECURE_TLS_NO_MATCHING_PSK);
}
#endif
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