summaryrefslogtreecommitdiff
path: root/lib/gnutls_state.c
blob: a8111ba7a77c23f7cff204012fd280f20d2cbdb3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
/*
 * Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
 * Free Software Foundation, Inc.
 *
 * Author: Nikos Mavrogiannopoulos
 *
 * This file is part of GnuTLS.
 *
 * The GnuTLS is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
 * USA
 *
 */

/* Functions to manipulate the session (gnutls_int.h), and some other stuff
 * are included here. The file's name is traditionally gnutls_state even if the
 * state has been renamed to session.
 */

#include <gnutls_int.h>
#include <gnutls_errors.h>
#include <gnutls_auth.h>
#include <gnutls_num.h>
#include <gnutls_datum.h>
#include <gnutls_db.h>
#include <gnutls_record.h>
#include <gnutls_handshake.h>
#include <gnutls_dh.h>
#include <gnutls_buffers.h>
#include <gnutls_mbuffers.h>
#include <gnutls_state.h>
#include <gnutls_constate.h>
#include <auth/cert.h>
#include <auth/anon.h>
#include <auth/psk.h>
#include <gnutls_algorithms.h>
#include <gnutls_rsa_export.h>
#include <gnutls_extensions.h>
#include <system.h>
#include <gnutls/dtls.h>

/* These should really be static, but src/tests.c calls them.  Make
   them public functions?  */
void
_gnutls_rsa_pms_set_version (gnutls_session_t session,
                             unsigned char major, unsigned char minor);

void
_gnutls_session_cert_type_set (gnutls_session_t session,
                               gnutls_certificate_type_t ct)
{
  _gnutls_handshake_log("HSK[%p]: Selected certificate type %s (%d)\n", session,
        gnutls_certificate_type_get_name(ct), ct);
  session->security_parameters.cert_type = ct;
}

/**
 * gnutls_cipher_get:
 * @session: is a #gnutls_session_t structure.
 *
 * Get currently used cipher.
 *
 * Returns: the currently used cipher, a #gnutls_cipher_algorithm_t
 *   type.
 **/
gnutls_cipher_algorithm_t
gnutls_cipher_get (gnutls_session_t session)
{
  record_parameters_st *record_params;
  int ret;
  
  ret = _gnutls_epoch_get (session, EPOCH_READ_CURRENT, &record_params);
  if (ret < 0)
    return gnutls_assert_val(GNUTLS_CIPHER_NULL);

  return record_params->cipher_algorithm;
}

/**
 * gnutls_certificate_type_get:
 * @session: is a #gnutls_session_t structure.
 *
 * The certificate type is by default X.509, unless it is negotiated
 * as a TLS extension.
 *
 * Returns: the currently used #gnutls_certificate_type_t certificate
 *   type.
 **/
gnutls_certificate_type_t
gnutls_certificate_type_get (gnutls_session_t session)
{
  return session->security_parameters.cert_type;
}

/**
 * gnutls_kx_get:
 * @session: is a #gnutls_session_t structure.
 *
 * Get currently used key exchange algorithm.
 *
 * Returns: the key exchange algorithm used in the last handshake, a
 *   #gnutls_kx_algorithm_t value.
 **/
gnutls_kx_algorithm_t
gnutls_kx_get (gnutls_session_t session)
{
  return session->security_parameters.kx_algorithm;
}

/**
 * gnutls_mac_get:
 * @session: is a #gnutls_session_t structure.
 *
 * Get currently used MAC algorithm.
 *
 * Returns: the currently used mac algorithm, a
 *   #gnutls_mac_algorithm_t value.
 **/
gnutls_mac_algorithm_t
gnutls_mac_get (gnutls_session_t session)
{
  record_parameters_st *record_params;
  int ret;
  
  ret = _gnutls_epoch_get (session, EPOCH_READ_CURRENT, &record_params);
  if (ret < 0)
    return gnutls_assert_val(GNUTLS_MAC_NULL);

  return record_params->mac_algorithm;
}

/**
 * gnutls_compression_get:
 * @session: is a #gnutls_session_t structure.
 *
 * Get currently used compression algorithm.
 *
 * Returns: the currently used compression method, a
 *   #gnutls_compression_method_t value.
 **/
gnutls_compression_method_t
gnutls_compression_get (gnutls_session_t session)
{
  record_parameters_st *record_params;
  int ret;
  
  ret = _gnutls_epoch_get (session, EPOCH_READ_CURRENT, &record_params);
  if (ret < 0)
    return gnutls_assert_val(GNUTLS_COMP_NULL);

  return record_params->compression_algorithm;
}

/* Check if the given certificate type is supported.
 * This means that it is enabled by the priority functions,
 * and a matching certificate exists.
 */
int
_gnutls_session_cert_type_supported (gnutls_session_t session,
                                     gnutls_certificate_type_t cert_type)
{
  unsigned i;
  unsigned cert_found = 0;
  gnutls_certificate_credentials_t cred;

  if (session->security_parameters.entity == GNUTLS_SERVER)
    {
      cred = (gnutls_certificate_credentials_t)
        _gnutls_get_cred (session->key, GNUTLS_CRD_CERTIFICATE, NULL);

      if (cred == NULL)
        return GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE;

      if (cred->server_get_cert_callback == NULL
          && cred->get_cert_callback == NULL)
        {
          for (i = 0; i < cred->ncerts; i++)
            {
              if (cred->cert_list[i][0].type == cert_type)
                {
                  cert_found = 1;
                  break;
                }
            }

          if (cert_found == 0)
            /* no certificate is of that type.
             */
            return GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE;
        }
    }

  if (session->internals.priorities.cert_type.algorithms == 0
      && cert_type == DEFAULT_CERT_TYPE)
    return 0;

  for (i = 0; i < session->internals.priorities.cert_type.algorithms; i++)
    {
      if (session->internals.priorities.cert_type.priority[i] == cert_type)
        {
          return 0;             /* ok */
        }
    }

  return GNUTLS_E_UNSUPPORTED_CERTIFICATE_TYPE;
}


/* this function deinitializes all the internal parameters stored
 * in a session struct.
 */
inline static void
deinit_internal_params (gnutls_session_t session)
{
  if (session->internals.params.free_dh_params)
    gnutls_dh_params_deinit (session->internals.params.dh_params);

  if (session->internals.params.free_rsa_params)
    gnutls_rsa_params_deinit (session->internals.params.rsa_params);

  _gnutls_handshake_hash_buffers_clear (session);

  memset (&session->internals.params, 0, sizeof (session->internals.params));
}

/* This function will clear all the variables in internals
 * structure within the session, which depend on the current handshake.
 * This is used to allow further handshakes.
 */
static void
_gnutls_handshake_internal_state_init (gnutls_session_t session)
{
  session->internals.extensions_sent_size = 0;

  /* by default no selected certificate */
  session->internals.adv_version_major = 0;
  session->internals.adv_version_minor = 0;
  session->internals.direction = 0;

  /* use out of band data for the last
   * handshake messages received.
   */
  session->internals.last_handshake_in = -1;
  session->internals.last_handshake_out = -1;

  session->internals.resumable = RESUME_TRUE;
  
  session->internals.dtls.hsk_read_seq = 0;
  session->internals.dtls.hsk_write_seq = 0;
  session->internals.dtls.handshake_start_time = time(0);
}

void
_gnutls_handshake_internal_state_clear (gnutls_session_t session)
{
  _gnutls_handshake_internal_state_init (session);

  deinit_internal_params (session);
  
  _gnutls_epoch_gc(session);
}

#define MIN_DH_BITS 727
/**
 * gnutls_init:
 * @session: is a pointer to a #gnutls_session_t structure.
 * @flags: indicate if this session is to be used for server or client.
 *
 * This function initializes the current session to null. Every
 * session must be initialized before use, so internal structures can
 * be allocated.  This function allocates structures which can only
 * be free'd by calling gnutls_deinit().  Returns zero on success.
 *
 * @flags can be one of %GNUTLS_CLIENT and %GNUTLS_SERVER. For a DTLS
 * entity, the flags %GNUTLS_DATAGRAM and  %GNUTLS_NONBLOCK are
 * also available. The latter flag will enable a non-blocking
 * operation of the DTLS timers.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, or an error code.
 **/
int
gnutls_init (gnutls_session_t * session, unsigned int flags)
{
  int ret;
  record_parameters_st *epoch;

  *session = gnutls_calloc (1, sizeof (struct gnutls_session_int));
  if (*session == NULL)
    return GNUTLS_E_MEMORY_ERROR;

  ret = _gnutls_epoch_alloc (*session, 0, &epoch);
  if (ret < 0)
    {
      gnutls_assert ();
      return GNUTLS_E_MEMORY_ERROR;
    }

  /* Set all NULL algos on epoch 0 */
  _gnutls_epoch_set_null_algos (*session, epoch);

  (*session)->security_parameters.epoch_next = 1;

  (*session)->security_parameters.entity = (flags&GNUTLS_SERVER?GNUTLS_SERVER:GNUTLS_CLIENT);

  /* the default certificate type for TLS */
  (*session)->security_parameters.cert_type = DEFAULT_CERT_TYPE;

  /* Initialize buffers */
  _gnutls_buffer_init (&(*session)->internals.handshake_hash_buffer);

  _mbuffer_head_init (&(*session)->internals.record_buffer);
  _mbuffer_head_init (&(*session)->internals.record_send_buffer);
  _mbuffer_head_init (&(*session)->internals.record_recv_buffer);

  _mbuffer_head_init (&(*session)->internals.handshake_send_buffer);
  _gnutls_handshake_recv_buffer_init(*session);

  (*session)->key = gnutls_calloc (1, sizeof (struct gnutls_key_st));
  if ((*session)->key == NULL)
    {
      gnutls_free (*session);
      *session = NULL;
      return GNUTLS_E_MEMORY_ERROR;
    }

  (*session)->internals.expire_time = DEFAULT_EXPIRE_TIME;      /* one hour default */

  gnutls_dh_set_prime_bits ((*session), MIN_DH_BITS);

  gnutls_handshake_set_max_packet_length ((*session),
                                          MAX_HANDSHAKE_PACKET_SIZE);

  /* set the socket pointers to -1;
   */
  (*session)->internals.transport_recv_ptr = (gnutls_transport_ptr_t) - 1;
  (*session)->internals.transport_send_ptr = (gnutls_transport_ptr_t) - 1;

  /* set the default maximum record size for TLS
   */
  (*session)->security_parameters.max_record_recv_size =
    DEFAULT_MAX_RECORD_SIZE;
  (*session)->security_parameters.max_record_send_size =
    DEFAULT_MAX_RECORD_SIZE;

  /* everything else not initialized here is initialized
   * as NULL or 0. This is why calloc is used.
   */

  _gnutls_handshake_internal_state_init (*session);

  /* emulate old gnutls behavior for old applications that do not use the priority_*
   * functions.
   */
  (*session)->internals.priorities.sr = SR_PARTIAL;

#ifdef HAVE_WRITEV
  gnutls_transport_set_vec_push_function (*session, system_writev);
#else
  gnutls_transport_set_push_function (*session, system_write);
#endif
  gnutls_transport_set_pull_function (*session, system_read);
  gnutls_transport_set_errno_function (*session, system_errno);
  gnutls_transport_set_pull_timeout_function (*session, system_recv_timeout);

  if (flags & GNUTLS_DATAGRAM)
    {
      (*session)->internals.dtls.mtu = DTLS_DEFAULT_MTU;
      (*session)->internals.transport = GNUTLS_DGRAM;

      (*session)->internals.dtls.retrans_timeout = 1000;
      (*session)->internals.dtls.total_timeout = 60000;

      (*session)->internals.dtls.record_sw_size = 0;
    }
  else
    (*session)->internals.transport = GNUTLS_STREAM;
  
  if (flags & GNUTLS_NONBLOCK)
    (*session)->internals.dtls.blocking = 0;
  else
    (*session)->internals.dtls.blocking = 1;

  return 0;
}

/* returns RESUME_FALSE or RESUME_TRUE.
 */
int
_gnutls_session_is_resumable (gnutls_session_t session)
{
  return session->internals.resumable;
}


/**
 * gnutls_deinit:
 * @session: is a #gnutls_session_t structure.
 *
 * This function clears all buffers associated with the @session.
 * This function will also remove session data from the session
 * database if the session was terminated abnormally.
 **/
void
gnutls_deinit (gnutls_session_t session)
{
  unsigned int i;

  if (session == NULL)
    return;

  /* remove auth info firstly */
  _gnutls_free_auth_info (session);

  _gnutls_handshake_internal_state_clear (session);
  _gnutls_handshake_io_buffer_clear (session);
  _gnutls_ext_free_session_data (session);

  for (i = 0; i < MAX_EPOCH_INDEX; i++)
    if (session->record_parameters[i] != NULL)
      {
        _gnutls_epoch_free (session, session->record_parameters[i]);
        session->record_parameters[i] = NULL;
      }

  _gnutls_buffer_clear (&session->internals.handshake_hash_buffer);
  _mbuffer_head_clear (&session->internals.record_buffer);
  _mbuffer_head_clear (&session->internals.record_recv_buffer);
  _mbuffer_head_clear (&session->internals.record_send_buffer);

  gnutls_credentials_clear (session);
  _gnutls_selected_certs_deinit (session);

  if (session->key != NULL)
    {
      _gnutls_mpi_release (&session->key->KEY);
      _gnutls_mpi_release (&session->key->client_Y);
      _gnutls_mpi_release (&session->key->client_p);
      _gnutls_mpi_release (&session->key->client_g);

      _gnutls_mpi_release (&session->key->u);
      _gnutls_mpi_release (&session->key->a);
      _gnutls_mpi_release (&session->key->x);
      _gnutls_mpi_release (&session->key->A);
      _gnutls_mpi_release (&session->key->B);
      _gnutls_mpi_release (&session->key->b);

      /* RSA */
      _gnutls_mpi_release (&session->key->rsa[0]);
      _gnutls_mpi_release (&session->key->rsa[1]);

      _gnutls_mpi_release (&session->key->dh_secret);
      gnutls_free (session->key);

      session->key = NULL;
    }

  memset (session, 0, sizeof (struct gnutls_session_int));
  gnutls_free (session);
}

/* Returns the minimum prime bits that are acceptable.
 */
int
_gnutls_dh_get_allowed_prime_bits (gnutls_session_t session)
{
  return session->internals.dh_prime_bits;
}

int
_gnutls_dh_set_peer_public (gnutls_session_t session, bigint_t public)
{
  dh_info_st *dh;
  int ret;

  switch (gnutls_auth_get_type (session))
    {
    case GNUTLS_CRD_ANON:
      {
        anon_auth_info_t info;
        info = _gnutls_get_auth_info (session);
        if (info == NULL)
          return GNUTLS_E_INTERNAL_ERROR;

        dh = &info->dh;
        break;
      }
    case GNUTLS_CRD_PSK:
      {
        psk_auth_info_t info;
        info = _gnutls_get_auth_info (session);
        if (info == NULL)
          return GNUTLS_E_INTERNAL_ERROR;

        dh = &info->dh;
        break;
      }
    case GNUTLS_CRD_CERTIFICATE:
      {
        cert_auth_info_t info;

        info = _gnutls_get_auth_info (session);
        if (info == NULL)
          return GNUTLS_E_INTERNAL_ERROR;

        dh = &info->dh;
        break;
      }
    default:
      gnutls_assert ();
      return GNUTLS_E_INTERNAL_ERROR;
    }

  if (dh->public_key.data)
    _gnutls_free_datum (&dh->public_key);

  ret = _gnutls_mpi_dprint_lz (public, &dh->public_key);
  if (ret < 0)
    {
      gnutls_assert ();
      return ret;
    }

  return 0;
}

int
_gnutls_dh_set_secret_bits (gnutls_session_t session, unsigned bits)
{
  switch (gnutls_auth_get_type (session))
    {
    case GNUTLS_CRD_ANON:
      {
        anon_auth_info_t info;
        info = _gnutls_get_auth_info (session);
        if (info == NULL)
          return GNUTLS_E_INTERNAL_ERROR;
        info->dh.secret_bits = bits;
        break;
      }
    case GNUTLS_CRD_PSK:
      {
        psk_auth_info_t info;
        info = _gnutls_get_auth_info (session);
        if (info == NULL)
          return GNUTLS_E_INTERNAL_ERROR;
        info->dh.secret_bits = bits;
        break;
      }
    case GNUTLS_CRD_CERTIFICATE:
      {
        cert_auth_info_t info;

        info = _gnutls_get_auth_info (session);
        if (info == NULL)
          return GNUTLS_E_INTERNAL_ERROR;

        info->dh.secret_bits = bits;
        break;
    default:
        gnutls_assert ();
        return GNUTLS_E_INTERNAL_ERROR;
      }
    }

  return 0;
}

/* This function will set in the auth info structure the
 * RSA exponent and the modulus.
 */
int
_gnutls_rsa_export_set_pubkey (gnutls_session_t session,
                               bigint_t exponent, bigint_t modulus)
{
  cert_auth_info_t info;
  int ret;

  info = _gnutls_get_auth_info (session);
  if (info == NULL)
    return GNUTLS_E_INTERNAL_ERROR;

  if (info->rsa_export.modulus.data)
    _gnutls_free_datum (&info->rsa_export.modulus);

  if (info->rsa_export.exponent.data)
    _gnutls_free_datum (&info->rsa_export.exponent);

  ret = _gnutls_mpi_dprint_lz (modulus, &info->rsa_export.modulus);
  if (ret < 0)
    {
      gnutls_assert ();
      return ret;
    }

  ret = _gnutls_mpi_dprint_lz (exponent, &info->rsa_export.exponent);
  if (ret < 0)
    {
      gnutls_assert ();
      _gnutls_free_datum (&info->rsa_export.modulus);
      return ret;
    }

  return 0;
}


/* Sets the prime and the generator in the auth info structure.
 */
int
_gnutls_dh_set_group (gnutls_session_t session, bigint_t gen, bigint_t prime)
{
  dh_info_st *dh;
  int ret;

  switch (gnutls_auth_get_type (session))
    {
    case GNUTLS_CRD_ANON:
      {
        anon_auth_info_t info;
        info = _gnutls_get_auth_info (session);
        if (info == NULL)
          return GNUTLS_E_INTERNAL_ERROR;

        dh = &info->dh;
        break;
      }
    case GNUTLS_CRD_PSK:
      {
        psk_auth_info_t info;
        info = _gnutls_get_auth_info (session);
        if (info == NULL)
          return GNUTLS_E_INTERNAL_ERROR;

        dh = &info->dh;
        break;
      }
    case GNUTLS_CRD_CERTIFICATE:
      {
        cert_auth_info_t info;

        info = _gnutls_get_auth_info (session);
        if (info == NULL)
          return GNUTLS_E_INTERNAL_ERROR;

        dh = &info->dh;
        break;
      }
    default:
      gnutls_assert ();
      return GNUTLS_E_INTERNAL_ERROR;
    }

  if (dh->prime.data)
    _gnutls_free_datum (&dh->prime);

  if (dh->generator.data)
    _gnutls_free_datum (&dh->generator);

  /* prime
   */
  ret = _gnutls_mpi_dprint_lz (prime, &dh->prime);
  if (ret < 0)
    {
      gnutls_assert ();
      return ret;
    }

  /* generator
   */
  ret = _gnutls_mpi_dprint_lz (gen, &dh->generator);
  if (ret < 0)
    {
      gnutls_assert ();
      _gnutls_free_datum (&dh->prime);
      return ret;
    }

  return 0;
}

#ifdef ENABLE_OPENPGP
/**
 * gnutls_openpgp_send_cert:
 * @session: is a pointer to a #gnutls_session_t structure.
 * @status: is one of GNUTLS_OPENPGP_CERT, or GNUTLS_OPENPGP_CERT_FINGERPRINT
 *
 * This function will order gnutls to send the key fingerprint
 * instead of the key in the initial handshake procedure. This should
 * be used with care and only when there is indication or knowledge
 * that the server can obtain the client's key.
 **/
void
gnutls_openpgp_send_cert (gnutls_session_t session,
                          gnutls_openpgp_crt_status_t status)
{
  session->internals.pgp_fingerprint = status;
}
#endif

/**
 * gnutls_certificate_send_x509_rdn_sequence:
 * @session: is a pointer to a #gnutls_session_t structure.
 * @status: is 0 or 1
 *
 * If status is non zero, this function will order gnutls not to send
 * the rdnSequence in the certificate request message. That is the
 * server will not advertize it's trusted CAs to the peer. If status
 * is zero then the default behaviour will take effect, which is to
 * advertize the server's trusted CAs.
 *
 * This function has no effect in clients, and in authentication
 * methods other than certificate with X.509 certificates.
 **/
void
gnutls_certificate_send_x509_rdn_sequence (gnutls_session_t session,
                                           int status)
{
  session->internals.ignore_rdn_sequence = status;
}

#ifdef ENABLE_OPENPGP
int
_gnutls_openpgp_send_fingerprint (gnutls_session_t session)
{
  return session->internals.pgp_fingerprint;
}
#endif

/*-
 * _gnutls_record_set_default_version - Used to set the default version for the first record packet
 * @session: is a #gnutls_session_t structure.
 * @major: is a tls major version
 * @minor: is a tls minor version
 *
 * This function sets the default version that we will use in the first
 * record packet (client hello). This function is only useful to people
 * that know TLS internals and want to debug other implementations.
 -*/
void
_gnutls_record_set_default_version (gnutls_session_t session,
                                    unsigned char major, unsigned char minor)
{
  session->internals.default_record_version[0] = major;
  session->internals.default_record_version[1] = minor;
}

/**
 * gnutls_handshake_set_private_extensions:
 * @session: is a #gnutls_session_t structure.
 * @allow: is an integer (0 or 1)
 *
 * This function will enable or disable the use of private cipher
 * suites (the ones that start with 0xFF).  By default or if @allow
 * is 0 then these cipher suites will not be advertized nor used.
 *
 * Currently GnuTLS does not include such cipher-suites or
 * compression algorithms.
 *
 * Enabling the private ciphersuites when talking to other than
 * gnutls servers and clients may cause interoperability problems.
 **/
void
gnutls_handshake_set_private_extensions (gnutls_session_t session, int allow)
{
  session->internals.enable_private = allow;
}

inline static int
_gnutls_cal_PRF_A (gnutls_mac_algorithm_t algorithm,
                   const void *secret, int secret_size,
                   const void *seed, int seed_size, void *result)
{
  digest_hd_st td1;
  int ret;

  ret = _gnutls_hmac_init (&td1, algorithm, secret, secret_size);
  if (ret < 0)
    {
      gnutls_assert ();
      return ret;
    }

  _gnutls_hmac (&td1, seed, seed_size);
  _gnutls_hmac_deinit (&td1, result);

  return 0;
}

#define MAX_SEED_SIZE 200

/* Produces "total_bytes" bytes using the hash algorithm specified.
 * (used in the PRF function)
 */
static int
_gnutls_P_hash (gnutls_mac_algorithm_t algorithm,
                const opaque * secret, int secret_size,
                const opaque * seed, int seed_size,
                int total_bytes, opaque * ret)
{

  digest_hd_st td2;
  int i, times, how, blocksize, A_size;
  opaque final[MAX_HASH_SIZE], Atmp[MAX_SEED_SIZE];
  int output_bytes, result;

  if (seed_size > MAX_SEED_SIZE || total_bytes <= 0)
    {
      gnutls_assert ();
      return GNUTLS_E_INTERNAL_ERROR;
    }

  blocksize = _gnutls_hmac_get_algo_len (algorithm);

  output_bytes = 0;
  do
    {
      output_bytes += blocksize;
    }
  while (output_bytes < total_bytes);

  /* calculate A(0) */

  memcpy (Atmp, seed, seed_size);
  A_size = seed_size;

  times = output_bytes / blocksize;

  for (i = 0; i < times; i++)
    {
      result = _gnutls_hmac_init (&td2, algorithm, secret, secret_size);
      if (result < 0)
        {
          gnutls_assert ();
          return result;
        }

      /* here we calculate A(i+1) */
      if ((result =
           _gnutls_cal_PRF_A (algorithm, secret, secret_size, Atmp,
                              A_size, Atmp)) < 0)
        {
          gnutls_assert ();
          _gnutls_hmac_deinit (&td2, final);
          return result;
        }

      A_size = blocksize;

      _gnutls_hmac (&td2, Atmp, A_size);
      _gnutls_hmac (&td2, seed, seed_size);
      _gnutls_hmac_deinit (&td2, final);

      if ((1 + i) * blocksize < total_bytes)
        {
          how = blocksize;
        }
      else
        {
          how = total_bytes - (i) * blocksize;
        }

      if (how > 0)
        {
          memcpy (&ret[i * blocksize], final, how);
        }
    }

  return 0;
}

/* Xor's two buffers and puts the output in the first one.
 */
inline static void
_gnutls_xor (opaque * o1, opaque * o2, int length)
{
  int i;
  for (i = 0; i < length; i++)
    {
      o1[i] ^= o2[i];
    }
}



#define MAX_PRF_BYTES 200

/* The PRF function expands a given secret 
 * needed by the TLS specification. ret must have a least total_bytes
 * available.
 */
int
_gnutls_PRF (gnutls_session_t session,
             const opaque * secret, int secret_size, const char *label,
             int label_size, const opaque * seed, int seed_size,
             int total_bytes, void *ret)
{
  int l_s, s_seed_size;
  const opaque *s1, *s2;
  opaque s_seed[MAX_SEED_SIZE];
  opaque o1[MAX_PRF_BYTES], o2[MAX_PRF_BYTES];
  int result;
  gnutls_protocol_t ver = gnutls_protocol_get_version (session);

  if (total_bytes > MAX_PRF_BYTES)
    {
      gnutls_assert ();
      return GNUTLS_E_INTERNAL_ERROR;
    }
  /* label+seed = s_seed */
  s_seed_size = seed_size + label_size;

  if (s_seed_size > MAX_SEED_SIZE)
    {
      gnutls_assert ();
      return GNUTLS_E_INTERNAL_ERROR;
    }

  memcpy (s_seed, label, label_size);
  memcpy (&s_seed[label_size], seed, seed_size);

  if (_gnutls_version_has_selectable_prf (ver))
    {
      result =
        _gnutls_P_hash (GNUTLS_MAC_SHA256, secret, secret_size,
                        s_seed, s_seed_size, total_bytes, ret);
      if (result < 0)
        {
          gnutls_assert ();
          return result;
        }
    }
  else
    {
      l_s = secret_size / 2;

      s1 = &secret[0];
      s2 = &secret[l_s];

      if (secret_size % 2 != 0)
        {
          l_s++;
        }

      result =
        _gnutls_P_hash (GNUTLS_MAC_MD5, s1, l_s, s_seed, s_seed_size,
                        total_bytes, o1);
      if (result < 0)
        {
          gnutls_assert ();
          return result;
        }

      result =
        _gnutls_P_hash (GNUTLS_MAC_SHA1, s2, l_s, s_seed, s_seed_size,
                        total_bytes, o2);
      if (result < 0)
        {
          gnutls_assert ();
          return result;
        }

      _gnutls_xor (o1, o2, total_bytes);

      memcpy (ret, o1, total_bytes);
    }

  return 0;                     /* ok */

}

/**
 * gnutls_prf_raw:
 * @session: is a #gnutls_session_t structure.
 * @label_size: length of the @label variable.
 * @label: label used in PRF computation, typically a short string.
 * @seed_size: length of the @seed variable.
 * @seed: optional extra data to seed the PRF with.
 * @outsize: size of pre-allocated output buffer to hold the output.
 * @out: pre-allocate buffer to hold the generated data.
 *
 * Apply the TLS Pseudo-Random-Function (PRF) using the master secret
 * on some data.
 *
 * The @label variable usually contain a string denoting the purpose
 * for the generated data.  The @seed usually contain data such as the
 * client and server random, perhaps together with some additional
 * data that is added to guarantee uniqueness of the output for a
 * particular purpose.
 *
 * Because the output is not guaranteed to be unique for a particular
 * session unless @seed include the client random and server random
 * fields (the PRF would output the same data on another connection
 * resumed from the first one), it is not recommended to use this
 * function directly.  The gnutls_prf() function seed the PRF with the
 * client and server random fields directly, and is recommended if you
 * want to generate pseudo random data unique for each session.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, or an error code.
 **/
int
gnutls_prf_raw (gnutls_session_t session,
                size_t label_size,
                const char *label,
                size_t seed_size, const char *seed, size_t outsize, char *out)
{
  int ret;

  ret = _gnutls_PRF (session,
                     session->security_parameters.master_secret,
                     GNUTLS_MASTER_SIZE,
                     label,
                     label_size, (opaque *) seed, seed_size, outsize, out);

  return ret;
}

/**
 * gnutls_prf:
 * @session: is a #gnutls_session_t structure.
 * @label_size: length of the @label variable.
 * @label: label used in PRF computation, typically a short string.
 * @server_random_first: non-0 if server random field should be first in seed
 * @extra_size: length of the @extra variable.
 * @extra: optional extra data to seed the PRF with.
 * @outsize: size of pre-allocated output buffer to hold the output.
 * @out: pre-allocate buffer to hold the generated data.
 *
 * Apply the TLS Pseudo-Random-Function (PRF) using the master secret
 * on some data, seeded with the client and server random fields.
 *
 * The @label variable usually contain a string denoting the purpose
 * for the generated data.  The @server_random_first indicate whether
 * the client random field or the server random field should be first
 * in the seed.  Non-0 indicate that the server random field is first,
 * 0 that the client random field is first.
 *
 * The @extra variable can be used to add more data to the seed, after
 * the random variables.  It can be used to tie make sure the
 * generated output is strongly connected to some additional data
 * (e.g., a string used in user authentication).
 *
 * The output is placed in *@OUT, which must be pre-allocated.
 *
 * Returns: %GNUTLS_E_SUCCESS on success, or an error code.
 **/
int
gnutls_prf (gnutls_session_t session,
            size_t label_size,
            const char *label,
            int server_random_first,
            size_t extra_size, const char *extra, size_t outsize, char *out)
{
  int ret;
  opaque *seed;
  size_t seedsize = 2 * GNUTLS_RANDOM_SIZE + extra_size;

  seed = gnutls_malloc (seedsize);
  if (!seed)
    {
      gnutls_assert ();
      return GNUTLS_E_MEMORY_ERROR;
    }

  memcpy (seed, server_random_first ?
          session->security_parameters.server_random :
          session->security_parameters.client_random, GNUTLS_RANDOM_SIZE);
  memcpy (seed + GNUTLS_RANDOM_SIZE, server_random_first ?
          session->security_parameters.client_random :
          session->security_parameters.server_random, GNUTLS_RANDOM_SIZE);

  memcpy (seed + 2 * GNUTLS_RANDOM_SIZE, extra, extra_size);

  ret = _gnutls_PRF (session, session->security_parameters.master_secret,
                     GNUTLS_MASTER_SIZE,
                     label, label_size, seed, seedsize, outsize, out);

  gnutls_free (seed);

  return ret;
}

/**
 * gnutls_session_is_resumed:
 * @session: is a #gnutls_session_t structure.
 *
 * Check whether session is resumed or not.
 *
 * Returns: non zero if this session is resumed, or a zero if this is
 *   a new session.
 **/
int
gnutls_session_is_resumed (gnutls_session_t session)
{
  if (session->security_parameters.entity == GNUTLS_CLIENT)
    {
      if (session->security_parameters.session_id_size > 0 &&
          session->security_parameters.session_id_size ==
          session->internals.resumed_security_parameters.session_id_size
          && memcmp (session->security_parameters.session_id,
                     session->internals.
                     resumed_security_parameters.session_id,
                     session->security_parameters.session_id_size) == 0)
        return 1;
    }
  else
    {
      if (session->internals.resumed == RESUME_TRUE)
        return 1;
    }

  return 0;
}

/*-
 * _gnutls_session_is_export - Used to check whether this session is of export grade
 * @session: is a #gnutls_session_t structure.
 *
 * This function will return non zero if this session is of export grade.
 -*/
int
_gnutls_session_is_export (gnutls_session_t session)
{
  gnutls_cipher_algorithm_t cipher;

  cipher =
    _gnutls_cipher_suite_get_cipher_algo (&session->
                                          security_parameters.current_cipher_suite);

  if (_gnutls_cipher_get_export_flag (cipher) != 0)
    return 1;

  return 0;
}

/*-
 * _gnutls_session_is_psk - Used to check whether this session uses PSK kx
 * @session: is a #gnutls_session_t structure.
 *
 * This function will return non zero if this session uses a PSK key
 * exchange algorithm.
 -*/
int
_gnutls_session_is_psk (gnutls_session_t session)
{
  gnutls_kx_algorithm_t kx;

  kx =
    _gnutls_cipher_suite_get_kx_algo (&session->
                                      security_parameters.current_cipher_suite);
  if (kx == GNUTLS_KX_PSK || kx == GNUTLS_KX_DHE_PSK)
    return 1;

  return 0;
}

/**
 * gnutls_session_get_ptr:
 * @session: is a #gnutls_session_t structure.
 *
 * Get user pointer for session.  Useful in callbacks.  This is the
 *   pointer set with gnutls_session_set_ptr().
 *
 * Returns: the user given pointer from the session structure, or
 *   %NULL if it was never set.
 **/
void *
gnutls_session_get_ptr (gnutls_session_t session)
{
  return session->internals.user_ptr;
}

/**
 * gnutls_session_set_ptr:
 * @session: is a #gnutls_session_t structure.
 * @ptr: is the user pointer
 *
 * This function will set (associate) the user given pointer @ptr to
 * the session structure.  This is pointer can be accessed with
 * gnutls_session_get_ptr().
 **/
void
gnutls_session_set_ptr (gnutls_session_t session, void *ptr)
{
  session->internals.user_ptr = ptr;
}


/**
 * gnutls_record_get_direction:
 * @session: is a #gnutls_session_t structure.
 *
 * This function provides information about the internals of the
 * record protocol and is only useful if a prior gnutls function call
 * (e.g.  gnutls_handshake()) was interrupted for some reason, that
 * is, if a function returned %GNUTLS_E_INTERRUPTED or
 * %GNUTLS_E_AGAIN.  In such a case, you might want to call select()
 * or poll() before calling the interrupted gnutls function again.  To
 * tell you whether a file descriptor should be selected for either
 * reading or writing, gnutls_record_get_direction() returns 0 if the
 * interrupted function was trying to read data, and 1 if it was
 * trying to write data.
 *
 * Returns: 0 if trying to read data, 1 if trying to write data.
 **/
int
gnutls_record_get_direction (gnutls_session_t session)
{
  return session->internals.direction;
}

/*-
 * _gnutls_rsa_pms_set_version - Sets a version to be used at the RSA PMS
 * @session: is a #gnutls_session_t structure.
 * @major: is the major version to use
 * @minor: is the minor version to use
 *
 * This function will set the given version number to be used at the
 * RSA PMS secret. This is only useful to clients, which want to
 * test server's capabilities.
 -*/
void
_gnutls_rsa_pms_set_version (gnutls_session_t session,
                             unsigned char major, unsigned char minor)
{
  session->internals.rsa_pms_version[0] = major;
  session->internals.rsa_pms_version[1] = minor;
}

/**
 * gnutls_handshake_set_post_client_hello_function:
 * @session: is a #gnutls_session_t structure.
 * @func: is the function to be called
 *
 * This function will set a callback to be called after the client
 * hello has been received (callback valid in server side only). This
 * allows the server to adjust settings based on received extensions.
 *
 * Those settings could be ciphersuites, requesting certificate, or
 * anything else except for version negotiation (this is done before
 * the hello message is parsed).
 *
 * This callback must return 0 on success or a gnutls error code to
 * terminate the handshake.
 *
 * Warning: You should not use this function to terminate the
 * handshake based on client input unless you know what you are
 * doing. Before the handshake is finished there is no way to know if
 * there is a man-in-the-middle attack being performed.
 **/
void
gnutls_handshake_set_post_client_hello_function (gnutls_session_t session,
                                                 gnutls_handshake_post_client_hello_func
                                                 func)
{
  session->internals.user_hello_func = func;
}

/**
 * gnutls_session_enable_compatibility_mode:
 * @session: is a #gnutls_session_t structure.
 *
 * This function can be used to disable certain (security) features in
 * TLS in order to maintain maximum compatibility with buggy
 * clients. It is equivalent to calling:
 * gnutls_record_disable_padding()
 *
 * Normally only servers that require maximum compatibility with
 * everything out there, need to call this function.
 **/
void
gnutls_session_enable_compatibility_mode (gnutls_session_t session)
{
  gnutls_record_disable_padding (session);
}

/**
 * gnutls_session_channel_binding:
 * @session: is a #gnutls_session_t structure.
 * @cbtype: an #gnutls_channel_binding_t enumeration type
 * @cb: output buffer array with data
 *
 * Extract given channel binding data of the @cbtype (e.g.,
 * %GNUTLS_CB_TLS_UNIQUE) type.
 *
 * Returns: %GNUTLS_E_SUCCESS on success,
 * %GNUTLS_E_UNIMPLEMENTED_FEATURE if the @cbtype is unsupported,
 * %GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE if the data is not
 * currently available, or an error code.
 *
 * Since: 2.12.0
 **/
int
gnutls_session_channel_binding (gnutls_session_t session,
                                gnutls_channel_binding_t cbtype,
                                gnutls_datum_t * cb)
{
  if (cbtype != GNUTLS_CB_TLS_UNIQUE)
    return GNUTLS_E_UNIMPLEMENTED_FEATURE;

  if (!session->internals.initial_negotiation_completed)
    return GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE;

  cb->size = session->internals.cb_tls_unique_len;
  cb->data = gnutls_malloc (cb->size);
  if (cb->data == NULL)
    return GNUTLS_E_MEMORY_ERROR;

  memcpy (cb->data, session->internals.cb_tls_unique, cb->size);

  return 0;
}

/* returns overhead imposed by the record layer (encryption/compression)
 * etc. It does include the record layer headers.
 *
 * It may return a negative value on error.
 */
int _gnutls_record_overhead_rt(gnutls_session_t session)
{
record_parameters_st *params;
int total = 0, ret, iv_size;

  if (session->internals.initial_negotiation_completed == 0)
    return RECORD_HEADER_SIZE(session);

  ret = _gnutls_epoch_get (session, EPOCH_WRITE_CURRENT, &params);
  if (ret < 0)
    return gnutls_assert_val(ret);

  /* requires padding */
  iv_size = _gnutls_cipher_get_iv_size(params->cipher_algorithm);
  total += iv_size;

  if (_gnutls_cipher_is_block (params->cipher_algorithm) == CIPHER_BLOCK)
    {
      if (!IS_DTLS(session))
        total += MAX_PAD_SIZE;
      else
        total += iv_size; /* iv_size == block_size */
    }
  
  if (params->mac_algorithm == GNUTLS_MAC_AEAD)
    total += _gnutls_cipher_get_tag_size(params->cipher_algorithm);
  else
    {
      ret = _gnutls_hmac_get_algo_len(params->mac_algorithm);
      if (ret < 0)
        return gnutls_assert_val(ret);
      total+=ret;
    }

  if (params->compression_algorithm != GNUTLS_COMP_NULL)
    total += EXTRA_COMP_SIZE;
  
  total += RECORD_HEADER_SIZE(session);
  
  return total;
}