lib/ext/session_ticket.c

   1 /*
   2  * Copyright (C) 2009-2012 Free Software Foundation, Inc.
   3  *
   4  * Author: Daiki Ueno
   5  *
   6  * This file is part of GnuTLS.
   7  *
   8  * The GnuTLS is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public License
  10  * as published by the Free Software Foundation; either version 2.1 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program.  If not, see <http://www.gnu.org/licenses/>
  20  *
  21  */
  22
  23 #include <gnutls_int.h>
  24 #include <gnutls_errors.h>
  25 #include <gnutls_datum.h>
  26 #include <algorithms.h>
  27 #include <gnutls_handshake.h>
  28 #include <gnutls_num.h>
  29 #include <gnutls_constate.h>
  30 #include <gnutls_session_pack.h>
  31 #include <random.h>
  32 #include <ext/session_ticket.h>
  33 #include <gnutls_mbuffers.h>
  34 #include <gnutls_extensions.h>
  35 #include <gnutls_constate.h>
  36
  37 #ifdef ENABLE_SESSION_TICKETS
  38
  39 #define KEY_NAME_SIZE SESSION_TICKET_KEY_NAME_SIZE
  40 #define KEY_SIZE SESSION_TICKET_KEY_SIZE
  41 #define IV_SIZE 12 /* GCM */
  42
  43 #define TAG_SIZE 16 /* GCM */
  44
  45 static int session_ticket_recv_params(gnutls_session_t session,
  46                                       const uint8_t * data,
  47                                       size_t data_size);
  48 static int session_ticket_send_params(gnutls_session_t session,
  49                                       gnutls_buffer_st * extdata);
  50 static int session_ticket_unpack(gnutls_buffer_st * ps,
  51                                  extension_priv_data_t * _priv);
  52 static int session_ticket_pack(extension_priv_data_t _priv,
  53                                gnutls_buffer_st * ps);
  54 static void session_ticket_deinit_data(extension_priv_data_t priv);
  55
  56 extension_entry_st ext_mod_session_ticket = {
  57         .name = "SESSION TICKET",
  58         .type = GNUTLS_EXTENSION_SESSION_TICKET,
  59         .parse_type = GNUTLS_EXT_MANDATORY,
  60
  61         .recv_func = session_ticket_recv_params,
  62         .send_func = session_ticket_send_params,
  63         .pack_func = session_ticket_pack,
  64         .unpack_func = session_ticket_unpack,
  65         .deinit_func = session_ticket_deinit_data,
  66 };
  67
  68 #define SESSION_KEY_SIZE (SESSION_TICKET_KEY_NAME_SIZE+SESSION_TICKET_KEY_SIZE)
  69 #define NAME_POS (0)
  70 #define KEY_POS (SESSION_TICKET_KEY_NAME_SIZE)
  71
  72 typedef struct {
  73         int session_ticket_enable;
  74         int session_ticket_renew;
  75
  76         uint8_t *session_ticket;
  77         int session_ticket_len;
  78
  79         uint8_t key[SESSION_KEY_SIZE];
  80 } session_ticket_ext_st;
  81
  82 struct ticket_st {
  83         uint8_t key_name[KEY_NAME_SIZE];
  84         uint8_t IV[IV_SIZE];
  85         uint8_t *encrypted_state;
  86         uint16_t encrypted_state_len;
  87         uint8_t tag[TAG_SIZE];
  88 };
  89
  90 static int
  91 decrypt_ticket(gnutls_session_t session, session_ticket_ext_st * priv,
  92                struct ticket_st *ticket)
  93 {
  94         cipher_hd_st cipher_hd;
  95         gnutls_datum_t key, IV, state;
  96         uint8_t final[TAG_SIZE];
  97         time_t timestamp = gnutls_time(0);
  98         int ret;
  99
 100         /* Decrypt encrypted_state using 128-bit AES in CBC mode. */
 101         key.data = (void *) &priv->key[KEY_POS];
 102         key.size = KEY_SIZE;
 103         IV.data = ticket->IV;
 104         IV.size = IV_SIZE;
 105         ret =
 106             _gnutls_cipher_init(&cipher_hd,
 107                                 cipher_to_entry(GNUTLS_CIPHER_AES_128_GCM),
 108                                 &key, &IV, 0);
 109         if (ret < 0) {
 110                 gnutls_assert();
 111                 return ret;
 112         }
 113         ret = _gnutls_cipher_decrypt(&cipher_hd, ticket->encrypted_state,
 114                                      ticket->encrypted_state_len);
 115         if (ret < 0) {
 116                 gnutls_assert();
 117                 goto cleanup;
 118         }
 119
 120         _gnutls_cipher_tag(&cipher_hd, final, TAG_SIZE);
 121         if (memcmp(ticket->tag, final, TAG_SIZE) != 0) {
 122                 gnutls_assert();
 123                 ret = GNUTLS_E_DECRYPTION_FAILED;
 124                 goto cleanup;
 125         }
 126
 127         /* Unpack security parameters. */
 128         state.data = ticket->encrypted_state;
 129         state.size = ticket->encrypted_state_len;
 130         ret = _gnutls_session_unpack(session, &state);
 131         if (ret < 0) {
 132                 gnutls_assert();
 133                 goto cleanup;
 134         }
 135
 136         if (timestamp -
 137             session->internals.resumed_security_parameters.timestamp >
 138             session->internals.expire_time
 139             || session->internals.resumed_security_parameters.timestamp >
 140             timestamp) {
 141                 gnutls_assert();
 142                 ret = GNUTLS_E_EXPIRED;
 143                 goto cleanup;
 144         }
 145
 146         session->internals.resumed = RESUME_TRUE;
 147
 148         ret = 0;
 149 cleanup:
 150         _gnutls_cipher_deinit(&cipher_hd);
 151
 152         return ret;
 153
 154 }
 155
 156 static int
 157 encrypt_ticket(gnutls_session_t session, session_ticket_ext_st * priv,
 158                struct ticket_st *ticket)
 159 {
 160         cipher_hd_st cipher_hd;
 161         gnutls_datum_t key, IV;
 162         gnutls_datum_t state = {NULL,0}, encrypted_state = {NULL,0};
 163         uint8_t iv[IV_SIZE];
 164         uint32_t t;
 165         int ret;
 166
 167         /* Pack security parameters. */
 168         ret = _gnutls_session_pack(session, &state);
 169         if (ret < 0) {
 170                 gnutls_assert();
 171                 return ret;
 172         }
 173
 174         encrypted_state.size = state.size;
 175         encrypted_state.data = gnutls_malloc(encrypted_state.size);
 176         if (!encrypted_state.data) {
 177                 gnutls_assert();
 178                 ret = GNUTLS_E_MEMORY_ERROR;
 179                 goto cleanup;
 180         }
 181         memset(encrypted_state.data, 0, encrypted_state.size);
 182         memcpy(encrypted_state.data, state.data, state.size);
 183
 184         /* Encrypt state using 128-bit AES in GCM mode. */
 185         key.data = (void *) &priv->key[KEY_POS];
 186         key.size = KEY_SIZE;
 187         IV.data = iv;
 188         IV.size = IV_SIZE;
 189
 190         t = gnutls_time(0);
 191         memcpy(iv, &t, 4);
 192         ret = _gnutls_rnd(GNUTLS_RND_NONCE, iv+4, IV_SIZE-4);
 193         if (ret < 0) {
 194                 gnutls_assert();
 195                 goto cleanup;
 196         }
 197
 198         ret =
 199             _gnutls_cipher_init(&cipher_hd,
 200                                 cipher_to_entry(GNUTLS_CIPHER_AES_128_GCM),
 201                                 &key, &IV, 1);
 202         if (ret < 0) {
 203                 gnutls_assert();
 204                 goto cleanup;
 205         }
 206
 207         ret = _gnutls_cipher_encrypt(&cipher_hd, encrypted_state.data,
 208                                      encrypted_state.size);
 209         if (ret < 0) {
 210                 gnutls_assert();
 211                 goto cleanup2;
 212         }
 213
 214         _gnutls_cipher_tag(&cipher_hd, ticket->tag, TAG_SIZE);
 215
 216         /* Fill the ticket structure to compute MAC. */
 217         memcpy(ticket->key_name, &priv->key[NAME_POS], KEY_NAME_SIZE);
 218         memcpy(ticket->IV, IV.data, IV.size);
 219         ticket->encrypted_state_len = encrypted_state.size;
 220         ticket->encrypted_state = encrypted_state.data;
 221
 222         encrypted_state.data = NULL;
 223
 224         ret = 0;
 225
 226 cleanup2:
 227         _gnutls_cipher_deinit(&cipher_hd);
 228
 229 cleanup:
 230         _gnutls_free_datum(&state);
 231         _gnutls_free_datum(&encrypted_state);
 232
 233         return ret;
 234 }
 235
 236 static int
 237 session_ticket_recv_params(gnutls_session_t session,
 238                            const uint8_t * data, size_t _data_size)
 239 {
 240         ssize_t data_size = _data_size;
 241         session_ticket_ext_st *priv = NULL;
 242         extension_priv_data_t epriv;
 243         int ret;
 244
 245         ret =
 246             _gnutls_ext_get_session_data(session,
 247                                          GNUTLS_EXTENSION_SESSION_TICKET,
 248                                          &epriv);
 249         if (ret < 0) {
 250                 return 0;
 251         }
 252         priv = epriv.ptr;
 253
 254         if (!priv->session_ticket_enable)
 255                 return 0;
 256
 257         if (session->security_parameters.entity == GNUTLS_SERVER) {
 258                 struct ticket_st ticket;
 259                 const uint8_t *encrypted_state;
 260                 int ret;
 261
 262                 /* The client requested a new session ticket. */
 263                 if (data_size == 0) {
 264                         priv->session_ticket_renew = 1;
 265                         return 0;
 266                 }
 267
 268                 DECR_LEN(data_size, KEY_NAME_SIZE);
 269                 memcpy(ticket.key_name, data, KEY_NAME_SIZE);
 270                 data += KEY_NAME_SIZE;
 271
 272                 /* If the key name of the ticket does not match the one that we
 273                    hold, issue a new ticket. */
 274                 if (memcmp
 275                     (ticket.key_name, &priv->key[NAME_POS],
 276                      KEY_NAME_SIZE)) {
 277                         priv->session_ticket_renew = 1;
 278                         return 0;
 279                 }
 280
 281                 DECR_LEN(data_size, IV_SIZE);
 282                 memcpy(ticket.IV, data, IV_SIZE);
 283                 data += IV_SIZE;
 284
 285                 DECR_LEN(data_size, 2);
 286                 ticket.encrypted_state_len = _gnutls_read_uint16(data);
 287                 data += 2;
 288
 289                 encrypted_state = data;
 290
 291                 DECR_LEN(data_size, ticket.encrypted_state_len);
 292                 data += ticket.encrypted_state_len;
 293
 294                 DECR_LEN(data_size, TAG_SIZE);
 295                 memcpy(ticket.tag, data, TAG_SIZE);
 296
 297                 ticket.encrypted_state =
 298                     gnutls_malloc(ticket.encrypted_state_len);
 299                 if (!ticket.encrypted_state) {
 300                         gnutls_assert();
 301                         return GNUTLS_E_MEMORY_ERROR;
 302                 }
 303                 memcpy(ticket.encrypted_state, encrypted_state,
 304                        ticket.encrypted_state_len);
 305
 306                 ret = decrypt_ticket(session, priv, &ticket);
 307                 gnutls_free(ticket.encrypted_state);
 308                 if (ret < 0) {
 309                         priv->session_ticket_renew = 1;
 310                         return 0;
 311                 }
 312         } else {                /* Client */
 313
 314                 if (data_size == 0) {
 315                         priv->session_ticket_renew = 1;
 316                         return 0;
 317                 }
 318         }
 319
 320         return 0;
 321 }
 322
 323 /* returns a positive number if we send the extension data, (0) if we
 324    do not want to send it, and a negative number on failure.
 325  */
 326 static int
 327 session_ticket_send_params(gnutls_session_t session,
 328                            gnutls_buffer_st * extdata)
 329 {
 330         session_ticket_ext_st *priv = NULL;
 331         extension_priv_data_t epriv;
 332         int ret;
 333
 334         ret =
 335             _gnutls_ext_get_session_data(session,
 336                                          GNUTLS_EXTENSION_SESSION_TICKET,
 337                                          &epriv);
 338         if (ret >= 0)
 339                 priv = epriv.ptr;
 340
 341         if (priv == NULL || !priv->session_ticket_enable)
 342                 return 0;
 343
 344         if (session->security_parameters.entity == GNUTLS_SERVER) {
 345                 if (priv && priv->session_ticket_renew) {
 346                         return GNUTLS_E_INT_RET_0;
 347                 }
 348         } else {
 349                 ret =
 350                     _gnutls_ext_get_resumed_session_data(session,
 351                                                          GNUTLS_EXTENSION_SESSION_TICKET,
 352                                                          &epriv);
 353                 if (ret >= 0)
 354                         priv = epriv.ptr;
 355
 356                 /* no previous data. Just advertize it */
 357                 if (ret < 0)
 358                         return GNUTLS_E_INT_RET_0;
 359
 360                 /* previous data had session tickets disabled. Don't advertize. Ignore. */
 361                 if (!priv->session_ticket_enable)
 362                         return 0;
 363
 364                 if (priv->session_ticket_len > 0) {
 365                         ret =
 366                             _gnutls_buffer_append_data(extdata,
 367                                                        priv->
 368                                                        session_ticket,
 369                                                        priv->
 370                                                        session_ticket_len);
 371                         if (ret < 0)
 372                                 return gnutls_assert_val(ret);
 373
 374                         return priv->session_ticket_len;
 375                 }
 376         }
 377         return 0;
 378 }
 379
 380
 381 static void session_ticket_deinit_data(extension_priv_data_t epriv)
 382 {
 383         session_ticket_ext_st *priv = epriv.ptr;
 384
 385         gnutls_free(priv->session_ticket);
 386         gnutls_free(priv);
 387 }
 388
 389 static int
 390 session_ticket_pack(extension_priv_data_t epriv, gnutls_buffer_st * ps)
 391 {
 392         session_ticket_ext_st *priv = epriv.ptr;
 393         int ret;
 394
 395         BUFFER_APPEND_PFX4(ps, priv->session_ticket,
 396                            priv->session_ticket_len);
 397         BUFFER_APPEND_NUM(ps, priv->session_ticket_enable);
 398
 399         return 0;
 400 }
 401
 402 static int
 403 session_ticket_unpack(gnutls_buffer_st * ps, extension_priv_data_t * _priv)
 404 {
 405         session_ticket_ext_st *priv = NULL;
 406         int ret;
 407         extension_priv_data_t epriv;
 408         gnutls_datum_t ticket;
 409
 410         priv = gnutls_calloc(1, sizeof(*priv));
 411         if (priv == NULL) {
 412                 gnutls_assert();
 413                 return GNUTLS_E_MEMORY_ERROR;
 414         }
 415
 416         BUFFER_POP_DATUM(ps, &ticket);
 417         priv->session_ticket = ticket.data;
 418         priv->session_ticket_len = ticket.size;
 419         BUFFER_POP_NUM(ps, priv->session_ticket_enable);
 420
 421         epriv.ptr = priv;
 422         *_priv = epriv;
 423
 424         return 0;
 425
 426       error:
 427         gnutls_free(priv);
 428         return ret;
 429 }
 430
 431
 432
 433 /**
 434  * gnutls_session_ticket_key_generate:
 435  * @key: is a pointer to a #gnutls_datum_t which will contain a newly
 436  * created key.
 437  *
 438  * Generate a random key to encrypt security parameters within
 439  * SessionTicket.
 440  *
 441  * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, or an
 442  * error code.
 443  *
 444  * Since: 2.10.0
 445  **/
 446 int gnutls_session_ticket_key_generate(gnutls_datum_t * key)
 447 {
 448         return gnutls_key_generate(key, SESSION_KEY_SIZE);
 449 }
 450
 451 /**
 452  * gnutls_session_ticket_enable_client:
 453  * @session: is a #gnutls_session_t structure.
 454  *
 455  * Request that the client should attempt session resumption using
 456  * SessionTicket.
 457  *
 458  * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, or an
 459  * error code.
 460  *
 461  * Since: 2.10.0
 462  **/
 463 int gnutls_session_ticket_enable_client(gnutls_session_t session)
 464 {
 465         session_ticket_ext_st *priv = NULL;
 466         extension_priv_data_t epriv;
 467
 468         if (!session) {
 469                 gnutls_assert();
 470                 return GNUTLS_E_INVALID_REQUEST;
 471         }
 472
 473         priv = gnutls_calloc(1, sizeof(*priv));
 474         if (priv == NULL) {
 475                 gnutls_assert();
 476                 return GNUTLS_E_MEMORY_ERROR;
 477         }
 478         priv->session_ticket_enable = 1;
 479         epriv.ptr = priv;
 480
 481         _gnutls_ext_set_session_data(session,
 482                                      GNUTLS_EXTENSION_SESSION_TICKET,
 483                                      epriv);
 484
 485         return 0;
 486 }
 487
 488 /**
 489  * gnutls_session_ticket_enable_server:
 490  * @session: is a #gnutls_session_t structure.
 491  * @key: key to encrypt session parameters.
 492  *
 493  * Request that the server should attempt session resumption using
 494  * SessionTicket.  @key must be initialized with
 495  * gnutls_session_ticket_key_generate().
 496  *
 497  * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, or an
 498  * error code.
 499  *
 500  * Since: 2.10.0
 501  **/
 502 int
 503 gnutls_session_ticket_enable_server(gnutls_session_t session,
 504                                     const gnutls_datum_t * key)
 505 {
 506         session_ticket_ext_st *priv = NULL;
 507         extension_priv_data_t epriv;
 508
 509         if (!session || !key || key->size != SESSION_KEY_SIZE) {
 510                 gnutls_assert();
 511                 return GNUTLS_E_INVALID_REQUEST;
 512         }
 513
 514         priv = gnutls_calloc(1, sizeof(*priv));
 515         if (priv == NULL) {
 516                 gnutls_assert();
 517                 return GNUTLS_E_MEMORY_ERROR;
 518         }
 519         epriv.ptr = priv;
 520
 521         memcpy(&priv->key, key->data, key->size);
 522         priv->session_ticket_enable = 1;
 523
 524         _gnutls_ext_set_session_data(session,
 525                                      GNUTLS_EXTENSION_SESSION_TICKET,
 526                                      epriv);
 527
 528         return 0;
 529 }
 530
 531 int _gnutls_send_new_session_ticket(gnutls_session_t session, int again)
 532 {
 533         mbuffer_st *bufel = NULL;
 534         uint8_t *data = NULL, *p;
 535         int data_size = 0;
 536         int ret;
 537         struct ticket_st ticket;
 538         uint16_t ticket_len;
 539         session_ticket_ext_st *priv = NULL;
 540         extension_priv_data_t epriv;
 541         uint16_t epoch_saved = session->security_parameters.epoch_write;
 542
 543         if (again == 0) {
 544                 ret =
 545                     _gnutls_ext_get_session_data(session,
 546                                                  GNUTLS_EXTENSION_SESSION_TICKET,
 547                                                  &epriv);
 548                 if (ret < 0)
 549                         return 0;
 550                 priv = epriv.ptr;
 551
 552                 if (!priv->session_ticket_renew)
 553                         return 0;
 554
 555                 /* XXX: Temporarily set write algorithms to be used.
 556                    _gnutls_write_connection_state_init() does this job, but it also
 557                    triggers encryption, while NewSessionTicket should not be
 558                    encrypted in the record layer. */
 559                 ret =
 560                     _gnutls_epoch_set_keys(session,
 561                                            session->security_parameters.
 562                                            epoch_next);
 563                 if (ret < 0) {
 564                         gnutls_assert();
 565                         return ret;
 566                 }
 567
 568                 session->security_parameters.epoch_write =
 569                     session->security_parameters.epoch_next;
 570
 571                 ret = encrypt_ticket(session, priv, &ticket);
 572                 session->security_parameters.epoch_write = epoch_saved;
 573                 if (ret < 0) {
 574                         gnutls_assert();
 575                         return ret;
 576                 }
 577
 578                 ticket_len =
 579                     KEY_NAME_SIZE + IV_SIZE + 2 +
 580                     ticket.encrypted_state_len + TAG_SIZE;
 581
 582                 bufel =
 583                     _gnutls_handshake_alloc(session,
 584                                             4 + 2 + ticket_len);
 585                 if (!bufel) {
 586                         gnutls_assert();
 587                         gnutls_free(ticket.encrypted_state);
 588                         return GNUTLS_E_MEMORY_ERROR;
 589                 }
 590
 591                 data = _mbuffer_get_udata_ptr(bufel);
 592                 p = data;
 593
 594                 _gnutls_write_uint32(session->internals.expire_time, p);
 595                 p += 4;
 596
 597                 _gnutls_write_uint16(ticket_len, p);
 598                 p += 2;
 599
 600                 memcpy(p, ticket.key_name, KEY_NAME_SIZE);
 601                 p += KEY_NAME_SIZE;
 602
 603                 memcpy(p, ticket.IV, IV_SIZE);
 604                 p += IV_SIZE;
 605
 606                 _gnutls_write_uint16(ticket.encrypted_state_len, p);
 607                 p += 2;
 608
 609                 memcpy(p, ticket.encrypted_state, ticket.encrypted_state_len);
 610                 gnutls_free(ticket.encrypted_state);
 611                 p += ticket.encrypted_state_len;
 612
 613                 memcpy(p, ticket.tag, TAG_SIZE);
 614                 p += TAG_SIZE;
 615
 616                 data_size = p - data;
 617
 618                 session->internals.ticket_sent = 1;
 619         }
 620         return _gnutls_send_handshake(session, data_size ? bufel : NULL,
 621                                       GNUTLS_HANDSHAKE_NEW_SESSION_TICKET);
 622 }
 623
 624 int _gnutls_recv_new_session_ticket(gnutls_session_t session)
 625 {
 626         uint8_t *p;
 627         int data_size;
 628         gnutls_buffer_st buf;
 629         uint16_t ticket_len;
 630         int ret;
 631         session_ticket_ext_st *priv = NULL;
 632         extension_priv_data_t epriv;
 633
 634         ret =
 635             _gnutls_ext_get_session_data(session,
 636                                          GNUTLS_EXTENSION_SESSION_TICKET,
 637                                          &epriv);
 638         if (ret < 0) {
 639                 gnutls_assert();
 640                 return 0;
 641         }
 642         priv = epriv.ptr;
 643
 644         if (!priv->session_ticket_renew)
 645                 return 0;
 646
 647         ret = _gnutls_recv_handshake(session,
 648                                      GNUTLS_HANDSHAKE_NEW_SESSION_TICKET,
 649                                      0, &buf);
 650         if (ret < 0)
 651                 return gnutls_assert_val_fatal(ret);
 652
 653         p = buf.data;
 654         data_size = buf.length;
 655
 656         DECR_LENGTH_COM(data_size, 4, ret =
 657                         GNUTLS_E_UNEXPECTED_PACKET_LENGTH;
 658                         goto error);
 659         /* skip over lifetime hint */
 660         p += 4;
 661
 662         DECR_LENGTH_COM(data_size, 2, ret =
 663                         GNUTLS_E_UNEXPECTED_PACKET_LENGTH;
 664                         goto error);
 665         ticket_len = _gnutls_read_uint16(p);
 666         p += 2;
 667
 668         DECR_LENGTH_COM(data_size, ticket_len, ret =
 669                         GNUTLS_E_UNEXPECTED_PACKET_LENGTH;
 670                         goto error);
 671         priv->session_ticket =
 672             gnutls_realloc_fast(priv->session_ticket, ticket_len);
 673         if (!priv->session_ticket) {
 674                 gnutls_assert();
 675                 ret = GNUTLS_E_MEMORY_ERROR;
 676                 goto error;
 677         }
 678         memcpy(priv->session_ticket, p, ticket_len);
 679         priv->session_ticket_len = ticket_len;
 680
 681         /* Discard the current session ID.  (RFC5077 3.4) */
 682         ret =
 683             _gnutls_generate_session_id(session->security_parameters.
 684                                         session_id,
 685                                         &session->security_parameters.
 686                                         session_id_size);
 687         if (ret < 0) {
 688                 gnutls_assert();
 689                 gnutls_free(priv->session_ticket);
 690                 priv->session_ticket = NULL;
 691                 ret = GNUTLS_E_INTERNAL_ERROR;
 692                 goto error;
 693         }
 694         ret = 0;
 695
 696       error:
 697         _gnutls_buffer_clear(&buf);
 698
 699         return ret;
 700 }
 701
 702 #endif