2 * TLS server tickets callbacks implementation
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4 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
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5 * SPDX-License-Identifier: Apache-2.0
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7 * Licensed under the Apache License, Version 2.0 (the "License"); you may
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8 * not use this file except in compliance with the License.
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9 * You may obtain a copy of the License at
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11 * http://www.apache.org/licenses/LICENSE-2.0
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13 * Unless required by applicable law or agreed to in writing, software
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14 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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15 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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16 * See the License for the specific language governing permissions and
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17 * limitations under the License.
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19 * This file is part of mbed TLS (https://tls.mbed.org)
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22 #if !defined(MBEDTLS_CONFIG_FILE)
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23 #include "mbedtls/config.h"
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25 #include MBEDTLS_CONFIG_FILE
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28 #if defined(MBEDTLS_SSL_TICKET_C)
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30 #if defined(MBEDTLS_PLATFORM_C)
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31 #include "mbedtls/platform.h"
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34 #define mbedtls_calloc calloc
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35 #define mbedtls_free free
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38 #include "mbedtls/ssl_ticket.h"
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39 #include "mbedtls/platform_util.h"
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46 void mbedtls_ssl_ticket_init( mbedtls_ssl_ticket_context *ctx )
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48 memset( ctx, 0, sizeof( mbedtls_ssl_ticket_context ) );
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50 #if defined(MBEDTLS_THREADING_C)
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51 mbedtls_mutex_init( &ctx->mutex );
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55 #define MAX_KEY_BYTES 32 /* 256 bits */
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57 #define TICKET_KEY_NAME_BYTES 4
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58 #define TICKET_IV_BYTES 12
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59 #define TICKET_CRYPT_LEN_BYTES 2
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60 #define TICKET_AUTH_TAG_BYTES 16
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62 #define TICKET_MIN_LEN ( TICKET_KEY_NAME_BYTES + \
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64 TICKET_CRYPT_LEN_BYTES + \
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65 TICKET_AUTH_TAG_BYTES )
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66 #define TICKET_ADD_DATA_LEN ( TICKET_KEY_NAME_BYTES + \
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68 TICKET_CRYPT_LEN_BYTES )
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71 * Generate/update a key
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73 static int ssl_ticket_gen_key( mbedtls_ssl_ticket_context *ctx,
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74 unsigned char index )
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77 unsigned char buf[MAX_KEY_BYTES];
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78 mbedtls_ssl_ticket_key *key = ctx->keys + index;
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80 #if defined(MBEDTLS_HAVE_TIME)
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81 key->generation_time = (uint32_t) mbedtls_time( NULL );
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84 if( ( ret = ctx->f_rng( ctx->p_rng, key->name, sizeof( key->name ) ) ) != 0 )
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87 if( ( ret = ctx->f_rng( ctx->p_rng, buf, sizeof( buf ) ) ) != 0 )
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90 /* With GCM and CCM, same context can encrypt & decrypt */
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91 ret = mbedtls_cipher_setkey( &key->ctx, buf,
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92 mbedtls_cipher_get_key_bitlen( &key->ctx ),
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95 mbedtls_platform_zeroize( buf, sizeof( buf ) );
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101 * Rotate/generate keys if necessary
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103 static int ssl_ticket_update_keys( mbedtls_ssl_ticket_context *ctx )
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105 #if !defined(MBEDTLS_HAVE_TIME)
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108 if( ctx->ticket_lifetime != 0 )
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110 uint32_t current_time = (uint32_t) mbedtls_time( NULL );
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111 uint32_t key_time = ctx->keys[ctx->active].generation_time;
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113 if( current_time >= key_time &&
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114 current_time - key_time < ctx->ticket_lifetime )
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119 ctx->active = 1 - ctx->active;
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121 return( ssl_ticket_gen_key( ctx, ctx->active ) );
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124 #endif /* MBEDTLS_HAVE_TIME */
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129 * Setup context for actual use
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131 int mbedtls_ssl_ticket_setup( mbedtls_ssl_ticket_context *ctx,
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132 int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
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133 mbedtls_cipher_type_t cipher,
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134 uint32_t lifetime )
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137 const mbedtls_cipher_info_t *cipher_info;
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139 ctx->f_rng = f_rng;
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140 ctx->p_rng = p_rng;
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142 ctx->ticket_lifetime = lifetime;
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144 cipher_info = mbedtls_cipher_info_from_type( cipher);
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145 if( cipher_info == NULL )
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146 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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148 if( cipher_info->mode != MBEDTLS_MODE_GCM &&
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149 cipher_info->mode != MBEDTLS_MODE_CCM )
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151 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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154 if( cipher_info->key_bitlen > 8 * MAX_KEY_BYTES )
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155 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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157 #if defined(MBEDTLS_USE_PSA_CRYPTO)
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158 ret = mbedtls_cipher_setup_psa( &ctx->keys[0].ctx,
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159 cipher_info, TICKET_AUTH_TAG_BYTES );
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160 if( ret != 0 && ret != MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
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162 /* We don't yet expect to support all ciphers through PSA,
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163 * so allow fallback to ordinary mbedtls_cipher_setup(). */
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164 if( ret == MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
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165 #endif /* MBEDTLS_USE_PSA_CRYPTO */
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166 if( ( ret = mbedtls_cipher_setup( &ctx->keys[0].ctx, cipher_info ) ) != 0 )
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169 #if defined(MBEDTLS_USE_PSA_CRYPTO)
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170 ret = mbedtls_cipher_setup_psa( &ctx->keys[1].ctx,
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171 cipher_info, TICKET_AUTH_TAG_BYTES );
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172 if( ret != 0 && ret != MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
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174 if( ret == MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE )
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175 #endif /* MBEDTLS_USE_PSA_CRYPTO */
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176 if( ( ret = mbedtls_cipher_setup( &ctx->keys[1].ctx, cipher_info ) ) != 0 )
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179 if( ( ret = ssl_ticket_gen_key( ctx, 0 ) ) != 0 ||
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180 ( ret = ssl_ticket_gen_key( ctx, 1 ) ) != 0 )
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189 * Serialize a session in the following format:
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191 * - If MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is enabled:
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192 * 0 . n-1 session structure, n = sizeof(mbedtls_ssl_session)
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193 * n . n+2 peer_cert length = m (0 if no certificate)
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194 * n+3 . n+2+m peer cert ASN.1
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196 * - If MBEDTLS_SSL_KEEP_PEER_CERTIFICATE is disabled:
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197 * 0 . n-1 session structure, n = sizeof(mbedtls_ssl_session)
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198 * n . n length of peer certificate digest = k (0 if no digest)
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199 * n+1 . n+k peer certificate digest (digest type encoded in session)
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201 static int ssl_save_session( const mbedtls_ssl_session *session,
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202 unsigned char *buf, size_t buf_len,
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205 unsigned char *p = buf;
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206 size_t left = buf_len;
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207 #if defined(MBEDTLS_X509_CRT_PARSE_C)
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208 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
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211 size_t cert_digest_len;
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212 #endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
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213 #endif /* MBEDTLS_X509_CRT_PARSE_C */
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215 if( left < sizeof( mbedtls_ssl_session ) )
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216 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
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218 /* This also copies the values of pointer fields in the
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219 * session to be serialized, but they'll be ignored when
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220 * loading the session through ssl_load_session(). */
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221 memcpy( p, session, sizeof( mbedtls_ssl_session ) );
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222 p += sizeof( mbedtls_ssl_session );
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223 left -= sizeof( mbedtls_ssl_session );
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225 #if defined(MBEDTLS_X509_CRT_PARSE_C)
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226 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
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227 if( session->peer_cert == NULL )
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230 cert_len = session->peer_cert->raw.len;
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232 if( left < 3 + cert_len )
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233 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
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235 *p++ = (unsigned char)( ( cert_len >> 16 ) & 0xFF );
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236 *p++ = (unsigned char)( ( cert_len >> 8 ) & 0xFF );
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237 *p++ = (unsigned char)( ( cert_len ) & 0xFF );
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240 if( session->peer_cert != NULL )
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241 memcpy( p, session->peer_cert->raw.p, cert_len );
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245 #else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
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246 if( session->peer_cert_digest != NULL )
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247 cert_digest_len = 0;
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249 cert_digest_len = session->peer_cert_digest_len;
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251 if( left < 1 + cert_digest_len )
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252 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
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254 *p++ = (unsigned char) cert_digest_len;
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257 if( session->peer_cert_digest != NULL )
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258 memcpy( p, session->peer_cert_digest, cert_digest_len );
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260 p += cert_digest_len;
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261 left -= cert_digest_len;
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262 #endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
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263 #endif /* MBEDTLS_X509_CRT_PARSE_C */
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271 * Unserialise session, see ssl_save_session()
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273 static int ssl_load_session( mbedtls_ssl_session *session,
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274 const unsigned char *buf, size_t len )
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276 const unsigned char *p = buf;
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277 const unsigned char * const end = buf + len;
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278 #if defined(MBEDTLS_X509_CRT_PARSE_C)
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279 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
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282 size_t cert_digest_len;
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283 #endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
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284 #endif /* MBEDTLS_X509_CRT_PARSE_C */
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286 if( sizeof( mbedtls_ssl_session ) > (size_t)( end - p ) )
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287 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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289 memcpy( session, p, sizeof( mbedtls_ssl_session ) );
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290 p += sizeof( mbedtls_ssl_session );
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292 /* Non-NULL pointer fields of `session` are meaningless
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293 * and potentially harmful. Zeroize them for safety. */
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294 #if defined(MBEDTLS_X509_CRT_PARSE_C)
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295 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
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296 session->peer_cert = NULL;
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298 session->peer_cert_digest = NULL;
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299 #endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
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300 #endif /* MBEDTLS_X509_CRT_PARSE_C */
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301 #if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
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302 session->ticket = NULL;
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303 #endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
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305 #if defined(MBEDTLS_X509_CRT_PARSE_C)
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306 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
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307 /* Deserialize CRT from the end of the ticket. */
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308 if( 3 > (size_t)( end - p ) )
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309 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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311 cert_len = ( p[0] << 16 ) | ( p[1] << 8 ) | p[2];
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314 if( cert_len != 0 )
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318 if( cert_len > (size_t)( end - p ) )
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319 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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321 session->peer_cert = mbedtls_calloc( 1, sizeof( mbedtls_x509_crt ) );
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323 if( session->peer_cert == NULL )
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324 return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
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326 mbedtls_x509_crt_init( session->peer_cert );
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328 if( ( ret = mbedtls_x509_crt_parse_der( session->peer_cert,
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329 p, cert_len ) ) != 0 )
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331 mbedtls_x509_crt_free( session->peer_cert );
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332 mbedtls_free( session->peer_cert );
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333 session->peer_cert = NULL;
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339 #else /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
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340 /* Deserialize CRT digest from the end of the ticket. */
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341 if( 1 > (size_t)( end - p ) )
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342 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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344 cert_digest_len = (size_t) p[0];
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347 if( cert_digest_len != 0 )
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349 if( cert_digest_len > (size_t)( end - p ) ||
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350 cert_digest_len != session->peer_cert_digest_len )
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352 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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355 session->peer_cert_digest = mbedtls_calloc( 1, cert_digest_len );
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356 if( session->peer_cert_digest == NULL )
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357 return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
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359 memcpy( session->peer_cert_digest, p, cert_digest_len );
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360 p += cert_digest_len;
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362 #endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
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363 #endif /* MBEDTLS_X509_CRT_PARSE_C */
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366 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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372 * Create session ticket, with the following structure:
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375 * opaque key_name[4];
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377 * opaque encrypted_state<0..2^16-1>;
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381 * The key_name, iv, and length of encrypted_state are the additional
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382 * authenticated data.
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385 int mbedtls_ssl_ticket_write( void *p_ticket,
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386 const mbedtls_ssl_session *session,
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387 unsigned char *start,
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388 const unsigned char *end,
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390 uint32_t *ticket_lifetime )
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393 mbedtls_ssl_ticket_context *ctx = p_ticket;
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394 mbedtls_ssl_ticket_key *key;
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395 unsigned char *key_name = start;
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396 unsigned char *iv = start + TICKET_KEY_NAME_BYTES;
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397 unsigned char *state_len_bytes = iv + TICKET_IV_BYTES;
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398 unsigned char *state = state_len_bytes + TICKET_CRYPT_LEN_BYTES;
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399 unsigned char *tag;
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400 size_t clear_len, ciph_len;
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404 if( ctx == NULL || ctx->f_rng == NULL )
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405 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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407 /* We need at least 4 bytes for key_name, 12 for IV, 2 for len 16 for tag,
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408 * in addition to session itself, that will be checked when writing it. */
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409 if( end - start < TICKET_MIN_LEN )
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410 return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
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412 #if defined(MBEDTLS_THREADING_C)
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413 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
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417 if( ( ret = ssl_ticket_update_keys( ctx ) ) != 0 )
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420 key = &ctx->keys[ctx->active];
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422 *ticket_lifetime = ctx->ticket_lifetime;
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424 memcpy( key_name, key->name, TICKET_KEY_NAME_BYTES );
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426 if( ( ret = ctx->f_rng( ctx->p_rng, iv, TICKET_IV_BYTES ) ) != 0 )
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429 /* Dump session state */
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430 if( ( ret = ssl_save_session( session,
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431 state, end - state, &clear_len ) ) != 0 ||
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432 (unsigned long) clear_len > 65535 )
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436 state_len_bytes[0] = ( clear_len >> 8 ) & 0xff;
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437 state_len_bytes[1] = ( clear_len ) & 0xff;
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439 /* Encrypt and authenticate */
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440 tag = state + clear_len;
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441 if( ( ret = mbedtls_cipher_auth_encrypt( &key->ctx,
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442 iv, TICKET_IV_BYTES,
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443 /* Additional data: key name, IV and length */
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444 key_name, TICKET_ADD_DATA_LEN,
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445 state, clear_len, state, &ciph_len,
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446 tag, TICKET_AUTH_TAG_BYTES ) ) != 0 )
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450 if( ciph_len != clear_len )
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452 ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
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456 *tlen = TICKET_MIN_LEN + ciph_len;
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459 #if defined(MBEDTLS_THREADING_C)
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460 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
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461 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
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468 * Select key based on name
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470 static mbedtls_ssl_ticket_key *ssl_ticket_select_key(
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471 mbedtls_ssl_ticket_context *ctx,
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472 const unsigned char name[4] )
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476 for( i = 0; i < sizeof( ctx->keys ) / sizeof( *ctx->keys ); i++ )
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477 if( memcmp( name, ctx->keys[i].name, 4 ) == 0 )
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478 return( &ctx->keys[i] );
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484 * Load session ticket (see mbedtls_ssl_ticket_write for structure)
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486 int mbedtls_ssl_ticket_parse( void *p_ticket,
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487 mbedtls_ssl_session *session,
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488 unsigned char *buf,
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492 mbedtls_ssl_ticket_context *ctx = p_ticket;
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493 mbedtls_ssl_ticket_key *key;
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494 unsigned char *key_name = buf;
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495 unsigned char *iv = buf + TICKET_KEY_NAME_BYTES;
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496 unsigned char *enc_len_p = iv + TICKET_IV_BYTES;
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497 unsigned char *ticket = enc_len_p + TICKET_CRYPT_LEN_BYTES;
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498 unsigned char *tag;
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499 size_t enc_len, clear_len;
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501 if( ctx == NULL || ctx->f_rng == NULL )
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502 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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504 if( len < TICKET_MIN_LEN )
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505 return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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507 #if defined(MBEDTLS_THREADING_C)
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508 if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 )
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512 if( ( ret = ssl_ticket_update_keys( ctx ) ) != 0 )
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515 enc_len = ( enc_len_p[0] << 8 ) | enc_len_p[1];
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516 tag = ticket + enc_len;
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518 if( len != TICKET_MIN_LEN + enc_len )
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520 ret = MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
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525 if( ( key = ssl_ticket_select_key( ctx, key_name ) ) == NULL )
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527 /* We can't know for sure but this is a likely option unless we're
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528 * under attack - this is only informative anyway */
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529 ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED;
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533 /* Decrypt and authenticate */
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534 if( ( ret = mbedtls_cipher_auth_decrypt( &key->ctx,
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535 iv, TICKET_IV_BYTES,
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536 /* Additional data: key name, IV and length */
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537 key_name, TICKET_ADD_DATA_LEN,
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539 ticket, &clear_len,
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540 tag, TICKET_AUTH_TAG_BYTES ) ) != 0 )
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542 if( ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED )
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543 ret = MBEDTLS_ERR_SSL_INVALID_MAC;
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547 if( clear_len != enc_len )
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549 ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR;
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553 /* Actually load session */
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554 if( ( ret = ssl_load_session( session, ticket, clear_len ) ) != 0 )
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557 #if defined(MBEDTLS_HAVE_TIME)
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559 /* Check for expiration */
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560 mbedtls_time_t current_time = mbedtls_time( NULL );
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562 if( current_time < session->start ||
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563 (uint32_t)( current_time - session->start ) > ctx->ticket_lifetime )
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565 ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED;
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572 #if defined(MBEDTLS_THREADING_C)
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573 if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 )
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574 return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
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583 void mbedtls_ssl_ticket_free( mbedtls_ssl_ticket_context *ctx )
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585 mbedtls_cipher_free( &ctx->keys[0].ctx );
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586 mbedtls_cipher_free( &ctx->keys[1].ctx );
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588 #if defined(MBEDTLS_THREADING_C)
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589 mbedtls_mutex_free( &ctx->mutex );
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592 mbedtls_platform_zeroize( ctx, sizeof( mbedtls_ssl_ticket_context ) );
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595 #endif /* MBEDTLS_SSL_TICKET_C */
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