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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 */
/** */
/** Datagram Transport Layer Security (DTLS) */
/** */
/**************************************************************************/
/**************************************************************************/
#define NX_SECURE_SOURCE_CODE
#include "nx_secure_dtls.h"
#ifdef NX_SECURE_ENABLE_DTLS
#ifdef NX_SECURE_ENABLE_ECJPAKE_CIPHERSUITE
extern NX_CRYPTO_METHOD crypto_method_ec_secp256;
#endif /* NX_SECURE_ENABLE_ECJPAKE_CIPHERSUITE */
#ifdef NX_SECURE_ENABLE_ECC_CIPHERSUITE
static UINT _nx_secure_dtls_send_clienthello_sec_spf_extensions(NX_SECURE_TLS_SESSION *tls_session,
UCHAR *packet_buffer, ULONG *packet_offset,
USHORT *extension_length, ULONG available_size);
#endif /* NX_SECURE_ENABLE_ECC_CIPHERSUITE */
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_dtls_send_clienthello PORTABLE C */
/* 6.1.10 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function populates an NX_PACKET with a ClientHello message, */
/* which kicks off a DTLS handshake when sent to a remote DTLS server. */
/* */
/* INPUT */
/* */
/* dtls_session DTLS control block */
/* send_packet Outgoing TLS packet */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* _nx_secure_tls_handshake_hash_init Initialize the finished hash */
/* _nx_secure_tls_newest_supported_version */
/* Get the version of DTLS to use*/
/* [nx_crypto_init] Crypto initialization */
/* [nx_crypto_operation] Crypto operation */
/* [nx_secure_tls_session_time_function] Get the current time for the */
/* TLS timestamp */
/* */
/* CALLED BY */
/* */
/* nx_secure_dtls_session_start */
/* nx_secure_dtls_client_handshake */
/* */
/* RELEASE HISTORY */
/* */
/* DATE NAME DESCRIPTION */
/* */
/* 05-19-2020 Timothy Stapko Initial Version 6.0 */
/* 09-30-2020 Timothy Stapko Modified comment(s), */
/* verified memcpy use cases, */
/* resulting in version 6.1 */
/* 01-31-2022 Yuxin Zhou Modified comment(s), and */
/* updated cookie handling, */
/* resulting in version 6.1.10 */
/* */
/**************************************************************************/
UINT _nx_secure_dtls_send_clienthello(NX_SECURE_DTLS_SESSION *dtls_session, NX_PACKET *send_packet)
{
ULONG length;
UINT gmt_time;
UINT random_value;
UINT i;
USHORT ciphersuite;
USHORT ciphersuites_length;
#ifdef NX_SECURE_ENABLE_ECJPAKE_CIPHERSUITE
USHORT extension_length;
USHORT extension_type;
UINT status;
NX_SECURE_TLS_PSK_STORE *psk_store;
NX_CRYPTO_EXTENDED_OUTPUT extended_output;
#endif
#if defined(NX_SECURE_ENABLE_ECJPAKE_CIPHERSUITE) || defined(NX_SECURE_ENABLE_ECC_CIPHERSUITE)
UCHAR *extension_total_length_ptr;
USHORT extension_total_length;
const NX_CRYPTO_METHOD *crypto_method = NX_NULL;
#endif
UCHAR *packet_buffer;
NX_SECURE_TLS_SESSION *tls_session;
const NX_SECURE_TLS_CRYPTO *crypto_table;
USHORT protocol_version;
/* ClientHello structure:
* | 2 | 4 + 28 | 1 | <SID len> | 2 | <CS Len> | 1 | <Comp Len> | 2 | <Ext. Len> |
* | TLS version | Random (time + random) | SID length | Session ID | CS Len | Ciphersuites |Comp Len | Compression |Ext. Len | Extensions |
*/
tls_session = &dtls_session -> nx_secure_dtls_tls_session;
packet_buffer = send_packet -> nx_packet_prepend_ptr;
/* Initialize the handshake hashes used for the Finished message. */
_nx_secure_tls_handshake_hash_init(tls_session);
/* At this point, the remote session is not active - that is, incoming records are not encrypted. */
tls_session -> nx_secure_tls_remote_session_active = 0;
/* Since we are establishing a new session, we start in non-encrypted mode. */
tls_session -> nx_secure_tls_local_session_active = 0;
/* Length of the ciphersuites list that follows. The client can send any number of suites for the
* server to choose from, with a 2-byte length field. */
crypto_table = tls_session -> nx_secure_tls_crypto_table;
ciphersuites_length = (USHORT)(2 + (crypto_table -> nx_secure_tls_ciphersuite_lookup_table_size << 1));
if ((10u + sizeof(tls_session -> nx_secure_tls_key_material.nx_secure_tls_client_random) +
tls_session -> nx_secure_tls_session_id_length + dtls_session -> nx_secure_dtls_cookie_length + ciphersuites_length) >
((ULONG)(send_packet -> nx_packet_data_end) - (ULONG)(send_packet -> nx_packet_prepend_ptr)))
{
/* Packet buffer is too small. */
return(NX_SECURE_TLS_PACKET_BUFFER_TOO_SMALL);
}
/* First two bytes of the hello following the header are the DTLS major and minor version numbers. */
_nx_secure_tls_protocol_version_get(tls_session, &protocol_version, NX_SECURE_DTLS);
if (protocol_version == 0x0)
{
/* Error, no versions enabled. */
return(NX_SECURE_TLS_UNSUPPORTED_TLS_VERSION);
}
tls_session -> nx_secure_tls_protocol_version = protocol_version;
if (dtls_session -> nx_secure_dtls_cookie_length > 0)
{
/* Skip record header. */
send_packet -> nx_packet_prepend_ptr += (NX_SECURE_DTLS_RECORD_HEADER_SIZE +
NX_SECURE_DTLS_HANDSHAKE_HEADER_SIZE);
length = send_packet -> nx_packet_length - (NX_SECURE_DTLS_RECORD_HEADER_SIZE +
NX_SECURE_DTLS_HANDSHAKE_HEADER_SIZE);
/* Locate the buffer to add cookie. */
packet_buffer = send_packet -> nx_packet_prepend_ptr +
(2 + sizeof(tls_session -> nx_secure_tls_key_material.nx_secure_tls_client_random) +
1 + tls_session -> nx_secure_tls_session_id_length);
/* Put the length into the record. */
packet_buffer[0] = (UCHAR)dtls_session -> nx_secure_dtls_cookie_length;
packet_buffer++;
/* Move the data to insert cookie. */
NX_SECURE_MEMMOVE(packet_buffer + dtls_session -> nx_secure_dtls_cookie_length,
packet_buffer, (UINT)(send_packet -> nx_packet_append_ptr - packet_buffer));
/* Set cookie. */
NX_SECURE_MEMCPY(packet_buffer, dtls_session -> nx_secure_dtls_client_cookie_ptr,
dtls_session -> nx_secure_dtls_cookie_length); /* Use case of memcpy is verified. */
length += dtls_session -> nx_secure_dtls_cookie_length;
/* Finally, we have a complete length and can put it into the buffer. Before that,
save off and return the number of bytes we wrote and need to send. */
send_packet -> nx_packet_append_ptr = send_packet -> nx_packet_prepend_ptr + length;
send_packet -> nx_packet_length = length;
return(NX_SUCCESS);
}
/* Use our length as an index into the buffer. */
length = 0;
packet_buffer[length] = (UCHAR)((protocol_version & 0xFF00) >> 8);
packet_buffer[length + 1] = (UCHAR)(protocol_version & 0x00FF);
length += 2;
/* Set the Client random data, used in key generation. First 4 bytes is GMT time. */
gmt_time = 0;
if (tls_session -> nx_secure_tls_session_time_function != NX_NULL)
{
gmt_time = tls_session -> nx_secure_tls_session_time_function();
}
NX_CHANGE_ULONG_ENDIAN(gmt_time);
NX_SECURE_MEMCPY(tls_session -> nx_secure_tls_key_material.nx_secure_tls_client_random, (UCHAR *)&gmt_time, sizeof(gmt_time)); /* Use case of memcpy is verified. */
/* Next 28 bytes is random data. */
for (i = 0; i < 28; i += (UINT)sizeof(random_value))
{
random_value = (UINT)NX_RAND();
NX_CHANGE_ULONG_ENDIAN(random_value);
*(tls_session -> nx_secure_tls_key_material.nx_secure_tls_client_random + (i + 4)) = (UCHAR)(random_value);
*(tls_session -> nx_secure_tls_key_material.nx_secure_tls_client_random + (i + 5)) = (UCHAR)(random_value >> 8);
*(tls_session -> nx_secure_tls_key_material.nx_secure_tls_client_random + (i + 6)) = (UCHAR)(random_value >> 16);
*(tls_session -> nx_secure_tls_key_material.nx_secure_tls_client_random + (i + 7)) = (UCHAR)(random_value >> 24);
}
/* Copy the random data into the packet. */
NX_SECURE_MEMCPY(&packet_buffer[length], tls_session -> nx_secure_tls_key_material.nx_secure_tls_client_random,
sizeof(tls_session -> nx_secure_tls_key_material.nx_secure_tls_client_random)); /* Use case of memcpy is verified. */
length += sizeof(tls_session -> nx_secure_tls_key_material.nx_secure_tls_client_random);
/* Session ID length is one byte. */
packet_buffer[length] = tls_session -> nx_secure_tls_session_id_length;
length++;
/* Session ID follows. */
if (tls_session -> nx_secure_tls_session_id_length > 0)
{
NX_SECURE_MEMCPY(&packet_buffer[length], tls_session -> nx_secure_tls_session_id, tls_session -> nx_secure_tls_session_id_length); /* Use case of memcpy is verified. */
length += tls_session -> nx_secure_tls_session_id_length;
}
/* Cookie length - 0 for first client hello */
packet_buffer[length] = 0;
length += 1;
/* Length of the ciphersuites list that follows. The client can send any number of suites for the
* server to choose from, with a 2-byte length field. */
packet_buffer[length] = (UCHAR)((ciphersuites_length & 0xFF00) >> 8);
packet_buffer[length + 1] = (UCHAR)(ciphersuites_length & 0x00FF);
length += 2;
/* Our chosen ciphersuites. In sending a ClientHello, we need to include all the ciphersuites
* we are interested in speaking. This will be a list of ciphersuites the user has chosen to support
* and all of them will be presented to the remote server in this initial message. */
for (i = 0; i < crypto_table -> nx_secure_tls_ciphersuite_lookup_table_size; i++)
{
ciphersuite = crypto_table -> nx_secure_tls_ciphersuite_lookup_table[i].nx_secure_tls_ciphersuite;
packet_buffer[length] = (UCHAR)((ciphersuite & 0xFF00) >> 8);
packet_buffer[length + 1] = (UCHAR)(ciphersuite & 0x00FF);
length += 2;
#if defined(NX_SECURE_ENABLE_ECJPAKE_CIPHERSUITE) || defined(NX_SECURE_ENABLE_ECC_CIPHERSUITE)
if (crypto_table -> nx_secure_tls_ciphersuite_lookup_table[i].nx_secure_tls_public_auth -> nx_crypto_algorithm == NX_CRYPTO_KEY_EXCHANGE_ECJPAKE)
{
crypto_method = crypto_table -> nx_secure_tls_ciphersuite_lookup_table[i].nx_secure_tls_public_auth;
}
#endif /* NX_SECURE_ENABLE_ECJPAKE_CIPHERSUITE || NX_SECURE_ENABLE_ECC_CIPHERSUITE */
}
/* For the secure rengotiation indication extension, we need to send a
Signalling Ciphersuite Value (SCSV) as detailled in RFC5746. */
ciphersuite = TLS_EMPTY_RENEGOTIATION_INFO_SCSV;
packet_buffer[length] = (UCHAR)((ciphersuite & 0xFF00) >> 8);
packet_buffer[length + 1] = (UCHAR)(ciphersuite & 0x00FF);
length += 2;
/* Compression methods length - one byte. For now we only have the NULL method, for a length of 1. */
packet_buffer[length] = 0x1;
length++;
/* Compression methods - for now this is NULL. */
packet_buffer[length] = 0x0;
length++;
/* TLS extensions, once supported, will be here in the ClientHello. */
#ifdef NX_SECURE_ENABLE_ECJPAKE_CIPHERSUITE
if (crypto_method)
{
if (crypto_method -> nx_crypto_init == NX_NULL)
{
return(NX_SECURE_TLS_HANDSHAKE_FAILURE);
}
if (tls_session -> nx_secure_tls_credentials.nx_secure_tls_psk_count == 0)
{
return(NX_SECURE_TLS_HANDSHAKE_FAILURE);
}
if (((ULONG)(send_packet -> nx_packet_data_end) - (ULONG)(send_packet -> nx_packet_prepend_ptr)) < (20u + length))
{
/* Packet buffer is too small. */
return(NX_SECURE_TLS_PACKET_BUFFER_TOO_SMALL);
}
psk_store = &tls_session -> nx_secure_tls_credentials.nx_secure_tls_psk_store[0];
status = crypto_method -> nx_crypto_init((NX_CRYPTO_METHOD*)crypto_method,
psk_store -> nx_secure_tls_psk_data,
(USHORT)(psk_store -> nx_secure_tls_psk_data_size << 3),
NX_NULL,
tls_session -> nx_secure_public_auth_metadata_area,
tls_session -> nx_secure_public_auth_metadata_size);
if (status)
{
return(status);
}
status = crypto_method -> nx_crypto_operation(NX_CRYPTO_ECJPAKE_HASH_METHOD_SET,
NX_NULL,
(NX_CRYPTO_METHOD*)crypto_method,
NX_NULL,
(USHORT)(tls_session -> nx_secure_tls_handshake_hash.nx_secure_tls_handshake_hash_sha256_metadata_size << 3),
(UCHAR *)(tls_session -> nx_secure_tls_crypto_table -> nx_secure_tls_handshake_hash_sha256_method),
sizeof(NX_CRYPTO_METHOD),
NX_NULL, NX_NULL, 0,
tls_session -> nx_secure_public_auth_metadata_area,
tls_session -> nx_secure_public_auth_metadata_size,
NX_NULL, NX_NULL);
if (status)
{
return(status);
}
status = crypto_method -> nx_crypto_operation(NX_CRYPTO_ECJPAKE_CURVE_SET,
NX_NULL,
(NX_CRYPTO_METHOD*)crypto_method,
NX_NULL, 0,
(UCHAR *)&crypto_method_ec_secp256,
sizeof(NX_CRYPTO_METHOD),
NX_NULL, NX_NULL, 0,
tls_session -> nx_secure_public_auth_metadata_area,
tls_session -> nx_secure_public_auth_metadata_size,
NX_NULL, NX_NULL);
if (status)
{
return(status);
}
extension_total_length_ptr = &packet_buffer[length];
extension_total_length = 18;
length += 2;
/* Supported Elliptic Curves Extension. */
extension_type = NX_SECURE_TLS_EXTENSION_EC_GROUPS;
packet_buffer[length] = (UCHAR)((extension_type >> 8) & 0xFF);
packet_buffer[length + 1] = (UCHAR)(extension_type & 0xFF);
length += 2;
/* Supported Groups Length: 4. */
extension_length = 4;
packet_buffer[length] = (UCHAR)((extension_length >> 8) & 0xFF);
packet_buffer[length + 1] = (UCHAR)(extension_length & 0xFF);
length += 2;
/* Supported Groups List Length: 2. */
extension_length = 2;
packet_buffer[length] = (UCHAR)((extension_length >> 8) & 0xFF);
packet_buffer[length + 1] = (UCHAR)(extension_length & 0xFF);
length += 2;
/* Supported Group: secp256r1. */
extension_type = (USHORT)NX_CRYPTO_EC_SECP256R1;
packet_buffer[length] = (UCHAR)((extension_type >> 8) & 0xFF);
packet_buffer[length + 1] = (UCHAR)(extension_type & 0xFF);
length += 2;
/* ec_point_formats Extension. */
extension_type = NX_SECURE_TLS_EXTENSION_EC_POINT_FORMATS;
packet_buffer[length] = (UCHAR)((extension_type >> 8) & 0xFF);
packet_buffer[length + 1] = (UCHAR)(extension_type & 0xFF);
length += 2;
/* ec_point_formats Length: 2. */
extension_length = 2;
packet_buffer[length] = (UCHAR)((extension_length >> 8) & 0xFF);
packet_buffer[length + 1] = (UCHAR)(extension_length & 0xFF);
length += 2;
/* EC point formats Length: 1. */
packet_buffer[length] = 1;
length += 1;
/* EC point format: uncompressed(0). */
packet_buffer[length] = 0;
length += 1;
/* ecjpake_key_kp_pair Extension. */
extension_type = NX_SECURE_TLS_EXTENSION_ECJPAKE_KEY_KP_PAIR;
packet_buffer[length] = (UCHAR)((extension_type >> 8) & 0xFF);
packet_buffer[length + 1] = (UCHAR)(extension_type & 0xFF);
length += 2;
/* ecjpake_key_kp_pair Length. */
length += 2;
extended_output.nx_crypto_extended_output_data = &packet_buffer[length];
extended_output.nx_crypto_extended_output_length_in_byte =
(ULONG)send_packet -> nx_packet_data_end - (ULONG)&packet_buffer[length];
extended_output.nx_crypto_extended_output_actual_size = 0;
status = crypto_method -> nx_crypto_operation(NX_CRYPTO_ECJPAKE_CLIENT_HELLO_GENERATE,
NX_NULL,
(NX_CRYPTO_METHOD*)crypto_method,
NX_NULL, 0,
NX_NULL, 0, NX_NULL,
(UCHAR *)&extended_output,
sizeof(extended_output),
tls_session -> nx_secure_public_auth_metadata_area,
tls_session -> nx_secure_public_auth_metadata_size,
NX_NULL, NX_NULL);
if (status)
{
return(status);
}
/* Set length for ecjpake_key_kp_pair extension. */
extension_length = (USHORT)extended_output.nx_crypto_extended_output_actual_size;
packet_buffer[length - 2] = (UCHAR)((extension_length >> 8) & 0xFF);
packet_buffer[length - 1] = (UCHAR)(extension_length & 0xFF);
extension_total_length = (USHORT)(extension_total_length +
extended_output.nx_crypto_extended_output_actual_size);
length += extended_output.nx_crypto_extended_output_actual_size;
/* Set extension total length. */
extension_total_length_ptr[0] = (UCHAR)((extension_total_length >> 8) & 0xFF);
extension_total_length_ptr[1] = (UCHAR)(extension_total_length & 0xFF);
}
#endif
#ifdef NX_SECURE_ENABLE_ECC_CIPHERSUITE
if (crypto_method == NX_NULL)
{
extension_total_length_ptr = &packet_buffer[length];
extension_total_length = 18;
length += 2;
_nx_secure_dtls_send_clienthello_sec_spf_extensions(&dtls_session -> nx_secure_dtls_tls_session,
packet_buffer, &length, &extension_total_length,
((ULONG)send_packet -> nx_packet_data_end -
(ULONG)packet_buffer));
if (extension_total_length == 0)
{
/* No extensions, remove the extensions length. */
length -= 2;
}
else
{
/* Set extension total length. */
extension_total_length_ptr[0] = (UCHAR)((extension_total_length >> 8) & 0xFF);
extension_total_length_ptr[1] = (UCHAR)(extension_total_length & 0xFF);
}
}
#endif /* NX_SECURE_ENABLE_ECC_CIPHERSUITE */
/* Finally, we have a complete length and can put it into the buffer. Before that,
save off and return the number of bytes we wrote and need to send. */
send_packet -> nx_packet_append_ptr = send_packet -> nx_packet_prepend_ptr + length;
send_packet -> nx_packet_length = send_packet -> nx_packet_length + length;
/* We are starting a new handshake, so both local and remote sessions are not
* active. */
dtls_session -> nx_secure_dtls_tls_session.nx_secure_tls_remote_session_active = 0;
dtls_session -> nx_secure_dtls_tls_session.nx_secure_tls_local_session_active = 0;
return(NX_SUCCESS);
}
/**************************************************************************/
/* */
/* FUNCTION RELEASE */
/* */
/* _nx_secure_dtls_send_clienthello_sec_spf_extensions PORTABLE C */
/* 6.1 */
/* AUTHOR */
/* */
/* Timothy Stapko, Microsoft Corporation */
/* */
/* DESCRIPTION */
/* */
/* This function adds the Supported Elliptic Curves extension and the */
/* Supported Point Formats extension to an outgoing ClientHello */
/* record. See RFC 4492 section 5.1. */
/* */
/* INPUT */
/* */
/* tls_session TLS control block */
/* packet_buffer Outgoing TLS packet buffer */
/* packet_offset Offset into packet buffer */
/* extension_length Return length of data */
/* available_size Available size of buffer */
/* */
/* OUTPUT */
/* */
/* status Completion status */
/* */
/* CALLS */
/* */
/* None */
/* */
/* CALLED BY */
/* */
/* _nx_secure_dtls_send_clienthello Send TLS ClientHello extension*/
/* */
/* 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 */
/* */
/**************************************************************************/
#ifdef NX_SECURE_ENABLE_ECC_CIPHERSUITE
static UINT _nx_secure_dtls_send_clienthello_sec_spf_extensions(NX_SECURE_TLS_SESSION *tls_session,
UCHAR *packet_buffer, ULONG *packet_offset,
USHORT *extension_length,
ULONG available_size)
{
ULONG offset;
USHORT ext_len, list_len, ext, i;
NX_SECURE_TLS_ECC *ecc_info;
ecc_info = &(tls_session -> nx_secure_tls_ecc);
if (ecc_info -> nx_secure_tls_ecc_supported_groups_count == 0)
{
*extension_length = 0;
return(NX_SUCCESS);
}
/* Start with our passed-in packet offset. */
offset = *packet_offset;
if (available_size < (offset + 12u + (ULONG)(ecc_info -> nx_secure_tls_ecc_supported_groups_count << 1)))
{
/* Packet buffer too small. */
return(NX_SECURE_TLS_PACKET_BUFFER_TOO_SMALL);
}
/* Supported Elliptic Curves Extension. */
ext = NX_SECURE_TLS_EXTENSION_EC_GROUPS; /* Supported Groups */
list_len = (USHORT)(ecc_info -> nx_secure_tls_ecc_supported_groups_count * sizeof(USHORT));
ext_len = (USHORT)(list_len + 2);
packet_buffer[offset] = (UCHAR)((ext & 0xFF00) >> 8);
packet_buffer[offset + 1] = (UCHAR)(ext & 0x00FF);
offset += 2;
packet_buffer[offset] = (UCHAR)((ext_len & 0xFF00) >> 8);
packet_buffer[offset + 1] = (UCHAR)(ext_len & 0x00FF);
offset += 2;
packet_buffer[offset] = (UCHAR)((list_len & 0xFF00) >> 8);
packet_buffer[offset + 1] = (UCHAR)(list_len & 0x00FF);
offset += 2;
for (i = 0; i < ecc_info -> nx_secure_tls_ecc_supported_groups_count; i++)
{
packet_buffer[offset] = (UCHAR)((ecc_info -> nx_secure_tls_ecc_supported_groups[i] & 0xFF00) >> 8);
packet_buffer[offset + 1] = (UCHAR)(ecc_info -> nx_secure_tls_ecc_supported_groups[i] & 0x00FF);
offset += 2;
}
/* ec_point_formats Extension. */
ext = NX_SECURE_TLS_EXTENSION_EC_POINT_FORMATS;
ext_len = 2; /* ec_point_formats Length: 2. */
packet_buffer[offset] = (UCHAR)((ext & 0xFF00) >> 8);
packet_buffer[offset + 1] = (UCHAR)(ext & 0x00FF);
offset += 2;
packet_buffer[offset] = (UCHAR)((ext_len & 0xFF00) >> 8);
packet_buffer[offset + 1] = (UCHAR)(ext_len & 0x00FF);
offset += 2;
packet_buffer[offset] = 1;
offset += 1;
packet_buffer[offset] = 0;
offset += 1;
/* Return our updated packet offset. */
*extension_length = (USHORT)(offset - *packet_offset);
*packet_offset = offset;
return(NX_SUCCESS);
}
#endif /* NX_SECURE_ENABLE_ECC_CIPHERSUITE */
#endif /* NX_SECURE_ENABLE_DTLS */
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