aboutsummaryrefslogtreecommitdiff
path: root/src/mint/taler-mint-httpd_db.c
blob: 247a84e9ddae79edcac5bb70b16c725c0ebad710 (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
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
/*
  This file is part of TALER
  Copyright (C) 2014, 2015 Christian Grothoff (and other contributing authors)

  TALER is free software; you can redistribute it and/or modify it under the
  terms of the GNU General Public License as published by the Free Software
  Foundation; either version 3, or (at your option) any later version.

  TALER 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 General Public License for more details.

  You should have received a copy of the GNU General Public License along with
  TALER; see the file COPYING.  If not, If not, see <http://www.gnu.org/licenses/>
*/
/**
 * @file taler-mint-httpd_db.c
 * @brief High-level (transactional-layer) database operations for the mint.
 * @author Christian Grothoff
 */
#include "platform.h"
#include <pthread.h>
#include <jansson.h>
#include "taler-mint-httpd_responses.h"
#include "taler-mint-httpd_keystate.h"

/**
 * How often should we retry a transaction before giving up
 * (for transactions resulting in serialization/dead locks only).
 */
#define MAX_TRANSACTION_COMMIT_RETRIES 3

/**
 * Code to begin a transaction, must be inline as we define a block
 * that ends with #COMMIT_TRANSACTION() within which we perform a number
 * of retries.  Note that this code may call "return" internally, so
 * it must be called within a function where any cleanup will be done
 * by the caller. Furthermore, the function's return value must
 * match that of a #TMH_RESPONSE_reply_internal_db_error() status code.
 *
 * @param session session handle
 * @param connection connection handle
 */
#define START_TRANSACTION(session,connection)                 \
{ /* start new scope, will be ended by COMMIT_TRANSACTION() */\
  unsigned int transaction_retries = 0;                       \
  int transaction_commit_result;                              \
transaction_start_label: /* we will use goto for retries */   \
  if (GNUNET_OK !=                                            \
      TMH_plugin->start (TMH_plugin->cls,                     \
                         session))                            \
  {                                                           \
    GNUNET_break (0);                                         \
    return TMH_RESPONSE_reply_internal_db_error (connection); \
  }

/**
 * Code to conclude a transaction, dual to #START_TRANSACTION().  Note
 * that this code may call "return" internally, so it must be called
 * within a function where any cleanup will be done by the caller.
 * Furthermore, the function's return value must match that of a
 * #TMH_RESPONSE_reply_internal_db_error() status code.
 *
 * @param session session handle
 * @param connection connection handle
 */
#define COMMIT_TRANSACTION(session,connection)                             \
  transaction_commit_result =                                              \
    TMH_plugin->commit (TMH_plugin->cls,                                   \
                        session);                                          \
  if (GNUNET_SYSERR == transaction_commit_result)                          \
  {                                                                        \
    TALER_LOG_WARNING ("Transaction commit failed in %s\n", __FUNCTION__); \
    return TMH_RESPONSE_reply_commit_error (connection);                   \
  }                                                                        \
  if (GNUNET_NO == transaction_commit_result)                              \
  {                                                                        \
    TALER_LOG_WARNING ("Transaction commit failed in %s\n", __FUNCTION__); \
    if (transaction_retries++ <= MAX_TRANSACTION_COMMIT_RETRIES)           \
      goto transaction_start_label;                                        \
    TALER_LOG_WARNING ("Transaction commit failed %u times in %s\n",       \
                       transaction_retries,                                \
                       __FUNCTION__);                                      \
    return TMH_RESPONSE_reply_commit_error (connection);                   \
  }                                                                        \
} /* end of scope opened by BEGIN_TRANSACTION */


/**
 * Calculate the total value of all transactions performed.
 * Stores @a off plus the cost of all transactions in @a tl
 * in @a ret.
 *
 * @param tl transaction list to process
 * @param off offset to use as the starting value
 * @param ret where the resulting total is to be stored
 * @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
 */
static int
calculate_transaction_list_totals (struct TALER_MINTDB_TransactionList *tl,
                                   const struct TALER_Amount *off,
                                   struct TALER_Amount *ret)
{
  struct TALER_Amount spent = *off;
  struct TALER_MINTDB_TransactionList *pos;

  for (pos = tl; NULL != pos; pos = pos->next)
  {
    switch (pos->type)
    {
    case TALER_MINTDB_TT_DEPOSIT:
      if (GNUNET_OK !=
          TALER_amount_add (&spent,
                            &spent,
                            &pos->details.deposit->amount_with_fee))
      {
        GNUNET_break (0);
        return GNUNET_SYSERR;
      }
      break;
    case TALER_MINTDB_TT_REFRESH_MELT:
      if (GNUNET_OK !=
          TALER_amount_add (&spent,
                            &spent,
                            &pos->details.melt->amount_with_fee))
      {
        GNUNET_break (0);
        return GNUNET_SYSERR;
      }
      break;
    }
  }
  *ret = spent;
  return GNUNET_OK;
}


/**
 * Execute a deposit.  The validity of the coin and signature
 * have already been checked.  The database must now check that
 * the coin is not (double or over) spent, and execute the
 * transaction (record details, generate success or failure response).
 *
 * @param connection the MHD connection to handle
 * @param deposit information about the deposit
 * @return MHD result code
 */
int
TMH_DB_execute_deposit (struct MHD_Connection *connection,
                        const struct TALER_MINTDB_Deposit *deposit)
{
  struct TALER_MINTDB_Session *session;
  struct TALER_MINTDB_TransactionList *tl;
  struct TALER_Amount spent;
  struct TALER_Amount value;
  struct TALER_Amount amount_without_fee;
  struct TMH_KS_StateHandle *mks;
  struct TALER_MINTDB_DenominationKeyIssueInformation *dki;
  int ret;

  if (NULL == (session = TMH_plugin->get_session (TMH_plugin->cls,
                                                  TMH_test_mode)))
  {
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }
  if (GNUNET_YES ==
      TMH_plugin->have_deposit (TMH_plugin->cls,
                                session,
                                deposit))
  {
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_subtract (&amount_without_fee,
                                          &deposit->amount_with_fee,
                                          &deposit->deposit_fee));
    return TMH_RESPONSE_reply_deposit_success (connection,
                                               &deposit->coin.coin_pub,
                                               &deposit->h_wire,
                                               &deposit->h_contract,
                                               deposit->transaction_id,
                                               deposit->timestamp,
                                               deposit->refund_deadline,
                                               &deposit->merchant_pub,
                                               &amount_without_fee);
  }
  mks = TMH_KS_acquire ();
  dki = TMH_KS_denomination_key_lookup (mks,
                                        &deposit->coin.denom_pub,
					TMH_KS_DKU_DEPOSIT);
  if (NULL == dki)
  {
    TMH_KS_release (mks);
    return TMH_RESPONSE_reply_arg_invalid (connection,
                                           "denom_pub");
  }
  TALER_amount_ntoh (&value,
                     &dki->issue.properties.value);
  TMH_KS_release (mks);

  START_TRANSACTION (session, connection);

  /* fee for THIS transaction */
  spent = deposit->amount_with_fee;
  /* add cost of all previous transactions */
  tl = TMH_plugin->get_coin_transactions (TMH_plugin->cls,
                                          session,
                                          &deposit->coin.coin_pub);
  if (GNUNET_OK !=
      calculate_transaction_list_totals (tl,
                                         &spent,
                                         &spent))
  {
    TMH_plugin->free_coin_transaction_list (TMH_plugin->cls,
                                            tl);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }
  /* Check that cost of all transactions is smaller than
     the value of the coin. */
  if (0 < TALER_amount_cmp (&spent,
                            &value))
  {
    TMH_plugin->rollback (TMH_plugin->cls,
                          session);
    ret = TMH_RESPONSE_reply_deposit_insufficient_funds (connection,
                                                         tl);
    TMH_plugin->free_coin_transaction_list (TMH_plugin->cls,
                                            tl);
    return ret;
  }
  TMH_plugin->free_coin_transaction_list (TMH_plugin->cls,
                                          tl);

  if (GNUNET_OK !=
      TMH_plugin->insert_deposit (TMH_plugin->cls,
                                  session,
                                  deposit))
  {
    TALER_LOG_WARNING ("Failed to store /deposit information in database\n");
    TMH_plugin->rollback (TMH_plugin->cls,
                          session);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }

  COMMIT_TRANSACTION(session, connection);
  GNUNET_assert (GNUNET_OK ==
                 TALER_amount_subtract (&amount_without_fee,
                                        &deposit->amount_with_fee,
                                        &deposit->deposit_fee));
  return TMH_RESPONSE_reply_deposit_success (connection,
                                             &deposit->coin.coin_pub,
                                             &deposit->h_wire,
                                             &deposit->h_contract,
                                             deposit->transaction_id,
                                             deposit->timestamp,
                                             deposit->refund_deadline,
                                             &deposit->merchant_pub,
                                             &amount_without_fee);
}


/**
 * Execute a /reserve/status.  Given the public key of a reserve,
 * return the associated transaction history.
 *
 * @param connection the MHD connection to handle
 * @param reserve_pub public key of the reserve to check
 * @return MHD result code
 */
int
TMH_DB_execute_reserve_status (struct MHD_Connection *connection,
                               const struct TALER_ReservePublicKeyP *reserve_pub)
{
  struct TALER_MINTDB_Session *session;
  struct TALER_MINTDB_ReserveHistory *rh;
  int res;

  if (NULL == (session = TMH_plugin->get_session (TMH_plugin->cls,
                                                  TMH_test_mode)))
  {
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }
  rh = TMH_plugin->get_reserve_history (TMH_plugin->cls,
                                        session,
                                        reserve_pub);
  if (NULL == rh)
    return TMH_RESPONSE_reply_json_pack (connection,
                                         MHD_HTTP_NOT_FOUND,
                                         "{s:s, s:s}",
                                         "error", "Reserve not found",
                                         "parameter", "withdraw_pub");
  res = TMH_RESPONSE_reply_reserve_status_success (connection,
                                                    rh);
  TMH_plugin->free_reserve_history (TMH_plugin->cls,
                                    rh);
  return res;
}


/**
 * Try to execute /reserve/withdraw transaction.
 *
 * @param connection request we are handling
 * @param session database session we are using
 * @param reserve reserve to withdraw from
 * @param denomination_pub public key of the denomination requested
 * @param dki denomination to withdraw
 * @param blinded_msg blinded message to be signed
 * @param blinded_msg_len number of bytes in @a blinded_msg
 * @param h_blind hash of @a blinded_msg
 * @param signature signature over the withdraw request, to be stored in DB
 * @param denom_sig[out] where to write the resulting signature
 *        (used to release memory in case of transaction failure
 * @return MHD result code
 */
static int
execute_reserve_withdraw_transaction (struct MHD_Connection *connection,
                                      struct TALER_MINTDB_Session *session,
                                      struct TMH_KS_StateHandle *key_state,
                                      const struct TALER_ReservePublicKeyP *reserve,
                                      const struct TALER_DenominationPublicKey *denomination_pub,
                                      const struct TALER_MINTDB_DenominationKeyIssueInformation *dki,
                                      const char *blinded_msg,
                                      size_t blinded_msg_len,
                                      const struct GNUNET_HashCode *h_blind,
                                      const struct TALER_ReserveSignatureP *signature,
                                      struct TALER_DenominationSignature *denom_sig)
{
  struct TALER_MINTDB_ReserveHistory *rh;
  const struct TALER_MINTDB_ReserveHistory *pos;
  struct TALER_MINTDB_DenominationKeyIssueInformation *tdki;
  struct TALER_MINTDB_CollectableBlindcoin collectable;
  struct TALER_Amount amount_required;
  struct TALER_Amount deposit_total;
  struct TALER_Amount withdraw_total;
  struct TALER_Amount balance;
  struct TALER_Amount value;
  struct TALER_Amount fee_withdraw;
  int res;

  /* Check if balance is sufficient */
  START_TRANSACTION (session, connection);
  rh = TMH_plugin->get_reserve_history (TMH_plugin->cls,
                                        session,
                                        reserve);
  if (NULL == rh)
  {
    TMH_plugin->rollback (TMH_plugin->cls,
                          session);
    return TMH_RESPONSE_reply_arg_unknown (connection,
                                           "reserve_pub");
  }

  /* calculate amount required including fees */
  TALER_amount_ntoh (&value,
                     &dki->issue.properties.value);
  TALER_amount_ntoh (&fee_withdraw,
                     &dki->issue.properties.fee_withdraw);

  if (GNUNET_OK !=
      TALER_amount_add (&amount_required,
                        &value,
                        &fee_withdraw))
  {
    TMH_plugin->rollback (TMH_plugin->cls,
                          session);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }

  /* calculate balance of the reserve */
  res = 0;
  for (pos = rh; NULL != pos; pos = pos->next)
  {
    switch (pos->type)
    {
    case TALER_MINTDB_RO_BANK_TO_MINT:
      if (0 == (res & 1))
        deposit_total = pos->details.bank->amount;
      else
        if (GNUNET_OK !=
            TALER_amount_add (&deposit_total,
                              &deposit_total,
                              &pos->details.bank->amount))
        {
          TMH_plugin->rollback (TMH_plugin->cls,
                                session);
          return TMH_RESPONSE_reply_internal_db_error (connection);
        }
      res |= 1;
      break;
    case TALER_MINTDB_RO_WITHDRAW_COIN:
      tdki = TMH_KS_denomination_key_lookup (key_state,
                                             &pos->details.withdraw->denom_pub,
					     TMH_KS_DKU_WITHDRAW);
      if (NULL == tdki)
      {
        GNUNET_break (0);
        TMH_plugin->rollback (TMH_plugin->cls,
                              session);
        return TMH_RESPONSE_reply_internal_db_error (connection);
      }
      TALER_amount_ntoh (&value,
                         &tdki->issue.properties.value);
      if (0 == (res & 2))
        withdraw_total = value;
      else
        if (GNUNET_OK !=
            TALER_amount_add (&withdraw_total,
                              &withdraw_total,
                              &value))
        {
          TMH_plugin->rollback (TMH_plugin->cls,
                                session);
          return TMH_RESPONSE_reply_internal_db_error (connection);
        }
      res |= 2;
      break;
    }
  }
  if (0 == (res & 1))
  {
    /* did not encounter any deposit operations, how can we have a reserve? */
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }
  if (0 == (res & 2))
  {
    /* did not encounter any withdraw operations, set to zero */
    TALER_amount_get_zero (deposit_total.currency,
                           &withdraw_total);
  }
  /* All reserve balances should be non-negative */
  GNUNET_assert (GNUNET_SYSERR !=
                 TALER_amount_subtract (&balance,
                                        &deposit_total,
                                        &withdraw_total));
  if (0 < TALER_amount_cmp (&amount_required,
                            &balance))
  {
    TMH_plugin->rollback (TMH_plugin->cls,
                          session);
    res = TMH_RESPONSE_reply_reserve_withdraw_insufficient_funds (connection,
                                                                  rh);
    TMH_plugin->free_reserve_history (TMH_plugin->cls,
                                      rh);
    return res;
  }
  TMH_plugin->free_reserve_history (TMH_plugin->cls,
                                    rh);

  /* Balance is good, sign the coin! */
  denom_sig->rsa_signature
    = GNUNET_CRYPTO_rsa_sign (dki->denom_priv.rsa_private_key,
                              blinded_msg,
                              blinded_msg_len);
  if (NULL == denom_sig->rsa_signature)
  {
    GNUNET_break (0);
    TMH_plugin->rollback (TMH_plugin->cls,
                          session);
    return TMH_RESPONSE_reply_internal_error (connection,
                                              "Internal error");
  }
  collectable.sig = *denom_sig;
  collectable.denom_pub = *denomination_pub;
  collectable.amount_with_fee = amount_required;
  collectable.withdraw_fee = fee_withdraw;
  collectable.reserve_pub = *reserve;
  collectable.h_coin_envelope = *h_blind;
  collectable.reserve_sig = *signature;
  if (GNUNET_OK !=
      TMH_plugin->insert_withdraw_info (TMH_plugin->cls,
                                        session,
                                        &collectable))
  {
    GNUNET_break (0);
    TMH_plugin->rollback (TMH_plugin->cls,
                          session);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }
  COMMIT_TRANSACTION (session, connection);

  return TMH_RESPONSE_reply_reserve_withdraw_success (connection,
                                                      &collectable);
}



/**
 * Execute a "/reserve/withdraw". Given a reserve and a properly signed
 * request to withdraw a coin, check the balance of the reserve and
 * if it is sufficient, store the request and return the signed
 * blinded envelope.
 *
 * @param connection the MHD connection to handle
 * @param reserve public key of the reserve
 * @param denomination_pub public key of the denomination requested
 * @param blinded_msg blinded message to be signed
 * @param blinded_msg_len number of bytes in @a blinded_msg
 * @param signature signature over the withdraw request, to be stored in DB
 * @return MHD result code
 */
int
TMH_DB_execute_reserve_withdraw (struct MHD_Connection *connection,
                                 const struct TALER_ReservePublicKeyP *reserve,
                                 const struct TALER_DenominationPublicKey *denomination_pub,
                                 const char *blinded_msg,
                                 size_t blinded_msg_len,
                                 const struct TALER_ReserveSignatureP *signature)
{
  struct TALER_MINTDB_Session *session;
  struct TMH_KS_StateHandle *key_state;
  struct TALER_MINTDB_DenominationKeyIssueInformation *dki;
  struct TALER_MINTDB_CollectableBlindcoin collectable;
  struct TALER_DenominationSignature denom_sig;
  struct GNUNET_HashCode h_blind;
  int res;

  GNUNET_CRYPTO_hash (blinded_msg,
                      blinded_msg_len,
                      &h_blind);
  if (NULL == (session = TMH_plugin->get_session (TMH_plugin->cls,
                                                  TMH_test_mode)))
  {
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }
  res = TMH_plugin->get_withdraw_info (TMH_plugin->cls,
                                       session,
                                       &h_blind,
                                       &collectable);
  if (GNUNET_SYSERR == res)
  {
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }

  /* Don't sign again if we have already signed the coin */
  if (GNUNET_YES == res)
  {
    res = TMH_RESPONSE_reply_reserve_withdraw_success (connection,
                                                       &collectable);
    GNUNET_CRYPTO_rsa_signature_free (collectable.sig.rsa_signature);
    GNUNET_CRYPTO_rsa_public_key_free (collectable.denom_pub.rsa_public_key);
    return res;
  }
  GNUNET_assert (GNUNET_NO == res);

  key_state = TMH_KS_acquire ();
  dki = TMH_KS_denomination_key_lookup (key_state,
                                        denomination_pub,
					TMH_KS_DKU_WITHDRAW);
  if (NULL == dki)
  {
    TMH_KS_release (key_state);
    return TMH_RESPONSE_reply_json_pack (connection,
                                         MHD_HTTP_NOT_FOUND,
                                         "{s:s}",
                                         "error",
                                         "Denomination not found");
  }
  denom_sig.rsa_signature = NULL;
  res = execute_reserve_withdraw_transaction (connection,
                                              session,
                                              key_state,
                                              reserve,
                                              denomination_pub,
                                              dki,
                                              blinded_msg,
                                              blinded_msg_len,
                                              &h_blind,
                                              signature,
                                              &denom_sig);
  if (NULL != denom_sig.rsa_signature)
    GNUNET_CRYPTO_rsa_signature_free (denom_sig.rsa_signature);
  TMH_KS_release (key_state);
  return res;
}


/**
 * Parse coin melt requests from a JSON object and write them to
 * the database.
 *
 * @param connection the connection to send errors to
 * @param session the database connection
 * @param key_state the mint's key state
 * @param session_hash hash identifying the refresh session
 * @param coin_details details about the coin being melted
 * @param oldcoin_index what is the number assigned to this coin
 * @return #GNUNET_OK on success,
 *         #GNUNET_NO if an error message was generated,
 *         #GNUNET_SYSERR on internal errors (no response generated)
 */
static int
refresh_accept_melts (struct MHD_Connection *connection,
                      struct TALER_MINTDB_Session *session,
                      const struct TMH_KS_StateHandle *key_state,
                      const struct GNUNET_HashCode *session_hash,
                      const struct TMH_DB_MeltDetails *coin_details,
                      uint16_t oldcoin_index)
{
  struct TALER_MINTDB_DenominationKeyIssueInformation *dk;
  struct TALER_MINTDB_DenominationKeyInformationP *dki;
  struct TALER_MINTDB_TransactionList *tl;
  struct TALER_Amount coin_value;
  struct TALER_Amount coin_residual;
  struct TALER_Amount spent;
  struct TALER_MINTDB_RefreshMelt melt;
  int res;

  dk = TMH_KS_denomination_key_lookup (key_state,
                                       &coin_details->coin_info.denom_pub,
                                       TMH_KS_DKU_DEPOSIT);
  if (NULL == dk)
    return (MHD_YES ==
            TMH_RESPONSE_reply_arg_unknown (connection,
                                            "denom_pub"))
        ? GNUNET_NO : GNUNET_SYSERR;
  dki = &dk->issue;
  TALER_amount_ntoh (&coin_value,
                     &dki->properties.value);
  /* fee for THIS transaction; the melt amount includes the fee! */
  spent = coin_details->melt_amount_with_fee;
  /* add historic transaction costs of this coin */
  tl = TMH_plugin->get_coin_transactions (TMH_plugin->cls,
                                          session,
                                          &coin_details->coin_info.coin_pub);
  if (GNUNET_OK !=
      calculate_transaction_list_totals (tl,
                                         &spent,
                                         &spent))
  {
    GNUNET_break (0);
    TMH_plugin->free_coin_transaction_list (TMH_plugin->cls,
                                            tl);
    return (MHD_YES ==
            TMH_RESPONSE_reply_internal_db_error (connection))
      ? GNUNET_NO : GNUNET_SYSERR;
  }
  /* Refuse to refresh when the coin's value is insufficient
     for the cost of all transactions. */
  if (TALER_amount_cmp (&coin_value,
                        &spent) < 0)
  {
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_subtract (&coin_residual,
                                          &spent,
                                          &coin_details->melt_amount_with_fee));
    res = (MHD_YES ==
           TMH_RESPONSE_reply_refresh_melt_insufficient_funds (connection,
                                                               &coin_details->coin_info.coin_pub,
                                                               coin_value,
                                                               tl,
                                                               coin_details->melt_amount_with_fee,
                                                               coin_residual))
        ? GNUNET_NO : GNUNET_SYSERR;
    TMH_plugin->free_coin_transaction_list (TMH_plugin->cls,
                                            tl);
    return res;
  }
  TMH_plugin->free_coin_transaction_list (TMH_plugin->cls,
                                          tl);

  melt.coin = coin_details->coin_info;
  melt.coin_sig = coin_details->melt_sig;
  melt.session_hash = *session_hash;
  melt.amount_with_fee = coin_details->melt_amount_with_fee;
  melt.melt_fee = coin_details->melt_fee;
  if (GNUNET_OK !=
      TMH_plugin->insert_refresh_melt (TMH_plugin->cls,
                                       session,
                                       oldcoin_index,
                                       &melt))
  {
    GNUNET_break (0);
    return (MHD_YES ==
            TMH_RESPONSE_reply_internal_db_error (connection))
      ? GNUNET_NO : GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Execute a "/refresh/melt".  We have been given a list of valid
 * coins and a request to melt them into the given
 * @a refresh_session_pub.  Check that the coins all have the
 * required value left and if so, store that they have been
 * melted and confirm the melting operation to the client.
 *
 * @param connection the MHD connection to handle
 * @param session_hash hash code of the session the coins are melted into
 * @param num_new_denoms number of entries in @a denom_pubs, size of y-dimension of @a commit_coin array
 * @param denom_pubs public keys of the coins we want to withdraw in the end
 * @param coin_count number of entries in @a coin_melt_details, size of y-dimension of @a commit_link array
 * @param coin_melt_details signatures and (residual) value of the respective coin should be melted
 * @param commit_coin 2d array of coin commitments (what the mint is to sign
 *                    once the "/refres/reveal" of cut and choose is done),
 *                    x-dimension must be #TALER_CNC_KAPPA
 * @param commit_link 2d array of coin link commitments (what the mint is
 *                    to return via "/refresh/link" to enable linkage in the
 *                    future)
 *                    x-dimension must be #TALER_CNC_KAPPA
 * @return MHD result code
 */
int
TMH_DB_execute_refresh_melt (struct MHD_Connection *connection,
                             const struct GNUNET_HashCode *session_hash,
                             unsigned int num_new_denoms,
                             const struct TALER_DenominationPublicKey *denom_pubs,
                             unsigned int coin_count,
                             const struct TMH_DB_MeltDetails *coin_melt_details,
                             struct TALER_MINTDB_RefreshCommitCoin *const* commit_coin,
                             struct TALER_RefreshCommitLinkP *const* commit_link)
{
  struct TMH_KS_StateHandle *key_state;
  struct TALER_MINTDB_RefreshSession refresh_session;
  struct TALER_MINTDB_Session *session;
  int res;
  unsigned int i;

  if (NULL == (session = TMH_plugin->get_session (TMH_plugin->cls,
                                                  TMH_test_mode)))
  {
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }
  START_TRANSACTION (session, connection);
  res = TMH_plugin->get_refresh_session (TMH_plugin->cls,
                                         session,
                                         session_hash,
                                         &refresh_session);
  if (GNUNET_YES == res)
  {
    TMH_plugin->rollback (TMH_plugin->cls,
                          session);
    res = TMH_RESPONSE_reply_refresh_melt_success (connection,
                                                   session_hash,
                                                   refresh_session.noreveal_index);
    return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
  }
  if (GNUNET_SYSERR == res)
  {
    TMH_plugin->rollback (TMH_plugin->cls,
                          session);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }

  /* store 'global' session data */
  refresh_session.num_oldcoins = coin_count;
  refresh_session.num_newcoins = num_new_denoms;
  refresh_session.noreveal_index
      = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_STRONG,
                                  TALER_CNC_KAPPA);
  if (GNUNET_OK !=
      (res = TMH_plugin->create_refresh_session (TMH_plugin->cls,
                                                 session,
                                                 session_hash,
                                                 &refresh_session)))
  {
    TMH_plugin->rollback (TMH_plugin->cls,
                          session);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }

  /* Melt old coins and check that they had enough residual value */
  key_state = TMH_KS_acquire ();
  for (i=0;i<coin_count;i++)
  {
    if (GNUNET_OK !=
        (res = refresh_accept_melts (connection,
                                     session,
                                     key_state,
                                     session_hash,
                                     &coin_melt_details[i],
                                     i)))
    {
      TMH_KS_release (key_state);
      TMH_plugin->rollback (TMH_plugin->cls,
                            session);
      return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
    }
  }
  TMH_KS_release (key_state);

  /* store requested new denominations */
  if (GNUNET_OK !=
      TMH_plugin->insert_refresh_order (TMH_plugin->cls,
                                        session,
                                        session_hash,
                                        num_new_denoms,
                                        denom_pubs))
  {
    TMH_plugin->rollback (TMH_plugin->cls,
                          session);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }

  for (i = 0; i < TALER_CNC_KAPPA; i++)
  {
    if (GNUNET_OK !=
        TMH_plugin->insert_refresh_commit_coins (TMH_plugin->cls,
                                                 session,
                                                 session_hash,
                                                 i,
                                                 num_new_denoms,
                                                 commit_coin[i]))
    {
      TMH_plugin->rollback (TMH_plugin->cls,
                            session);
      return TMH_RESPONSE_reply_internal_db_error (connection);
    }
  }
  for (i = 0; i < TALER_CNC_KAPPA; i++)
  {
    if (GNUNET_OK !=
        TMH_plugin->insert_refresh_commit_links (TMH_plugin->cls,
                                                 session,
                                                 session_hash,
                                                 i,
                                                 coin_count,
                                                 commit_link[i]))
    {
      TMH_plugin->rollback (TMH_plugin->cls,
                            session);
      return TMH_RESPONSE_reply_internal_db_error (connection);
    }
  }

  COMMIT_TRANSACTION (session, connection);
  return TMH_RESPONSE_reply_refresh_melt_success (connection,
                                                  session_hash,
                                                  refresh_session.noreveal_index);
}


/**
 * Send an error response with the details of the original melt
 * commitment and the location of the mismatch.
 *
 * @param connection the MHD connection to handle
 * @param session database connection to use
 * @param session_hash hash of session to query
 * @param off commitment offset to check
 * @param index index of the mismatch
 * @param object_name name of the object with the problem
 * @return #GNUNET_NO if we generated the error message
 *         #GNUNET_SYSERR if we could not even generate an error message
 */
static int
send_melt_commitment_error (struct MHD_Connection *connection,
                            struct TALER_MINTDB_Session *session,
                            const struct GNUNET_HashCode *session_hash,
                            unsigned int off,
                            unsigned int index,
                            const char *object_name)
{
  struct TALER_MINTDB_MeltCommitment *mc;
  int ret;

  mc = TMH_plugin->get_melt_commitment (TMH_plugin->cls,
                                        session,
                                        session_hash);
  if (NULL == mc)
  {
    GNUNET_break (0);
    return (MHD_YES ==
            TMH_RESPONSE_reply_internal_error (connection,
                                               "Melt commitment assembly"))
      ? GNUNET_NO : GNUNET_SYSERR;
  }
  ret = (MHD_YES ==
         TMH_RESPONSE_reply_refresh_reveal_missmatch (connection,
                                                      mc,
                                                      off,
                                                      index,
                                                      object_name))
    ? GNUNET_NO : GNUNET_SYSERR;
  TMH_plugin->free_melt_commitment (TMH_plugin->cls,
                                    mc);
  return ret;
}


/**
 * Check if the given @a transfer_privs correspond to an honest
 * commitment for the given session.
 * Checks that the transfer private keys match their commitments.
 * Then derives the shared secret for each #TALER_CNC_KAPPA, and check that they match.
 *
 * @param connection the MHD connection to handle
 * @param session database connection to use
 * @param session_hash hash of session to query
 * @param off commitment offset to check
 * @param num_oldcoins size of the @a transfer_privs and @a melts arrays
 * @param transfer_privs private transfer keys
 * @param melts array of melted coins
 * @param num_newcoins number of newcoins being generated
 * @param denom_pubs array of @a num_newcoins keys for the new coins
 * @return #GNUNET_OK if the committment was honest,
 *         #GNUNET_NO if there was a problem and we generated an error message
 *         #GNUNET_SYSERR if we could not even generate an error message
 */
static int
check_commitment (struct MHD_Connection *connection,
                  struct TALER_MINTDB_Session *session,
                  const struct GNUNET_HashCode *session_hash,
                  unsigned int off,
                  unsigned int num_oldcoins,
                  const struct TALER_TransferPrivateKeyP *transfer_privs,
                  const struct TALER_MINTDB_RefreshMelt *melts,
                  unsigned int num_newcoins,
                  const struct TALER_DenominationPublicKey *denom_pubs)
{
  unsigned int j;
  struct TALER_LinkSecretP last_shared_secret;
  int secret_initialized = GNUNET_NO;
  struct TALER_RefreshCommitLinkP *commit_links;
  struct TALER_MINTDB_RefreshCommitCoin *commit_coins;

  commit_links = GNUNET_malloc (num_oldcoins *
                                sizeof (struct TALER_RefreshCommitLinkP));
  if (GNUNET_OK !=
      TMH_plugin->get_refresh_commit_links (TMH_plugin->cls,
                                            session,
                                            session_hash,
                                            off,
                                            num_oldcoins,
                                            commit_links))
  {
    GNUNET_break (0);
    GNUNET_free (commit_links);
    return (MHD_YES == TMH_RESPONSE_reply_internal_db_error (connection))
        ? GNUNET_NO : GNUNET_SYSERR;
  }

  for (j = 0; j < num_oldcoins; j++)
  {
    struct TALER_LinkSecretP shared_secret;
    struct TALER_TransferPublicKeyP transfer_pub_check;

    GNUNET_CRYPTO_ecdhe_key_get_public (&transfer_privs[j].ecdhe_priv,
                                        &transfer_pub_check.ecdhe_pub);
    if (0 !=
        memcmp (&transfer_pub_check,
                &commit_links[j].transfer_pub,
                sizeof (struct TALER_TransferPublicKeyP)))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  "transfer keys do not match\n");
      GNUNET_free (commit_links);
      return send_melt_commitment_error (connection,
                                         session,
                                         session_hash,
                                         off,
                                         j,
                                         "transfer key");
    }

    if (GNUNET_OK !=
	TALER_link_decrypt_secret (&commit_links[j].shared_secret_enc,
				   &transfer_privs[j],
				   &melts[j].coin.coin_pub,
				   &shared_secret))
    {
      GNUNET_free (commit_links);
      return (MHD_YES ==
	      TMH_RESPONSE_reply_internal_error (connection,
						 "Transfer secret decryption error"))
	? GNUNET_NO : GNUNET_SYSERR;
    }
    if (GNUNET_NO == secret_initialized)
    {
      secret_initialized = GNUNET_YES;
      last_shared_secret = shared_secret;
    }
    else if (0 != memcmp (&shared_secret,
                          &last_shared_secret,
                          sizeof (struct GNUNET_HashCode)))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  "shared secrets do not match\n");
      GNUNET_free (commit_links);
      return send_melt_commitment_error (connection,
                                         session,
                                         session_hash,
                                         off,
                                         j,
                                         "transfer secret");
    }
  }
  GNUNET_break (GNUNET_YES == secret_initialized);
  GNUNET_free (commit_links);

  /* Check that the commitments for all new coins were correct */
  commit_coins = GNUNET_malloc (num_newcoins *
                                sizeof (struct TALER_MINTDB_RefreshCommitCoin));

  if (GNUNET_OK !=
      TMH_plugin->get_refresh_commit_coins (TMH_plugin->cls,
                                            session,
                                            session_hash,
                                            off,
                                            num_newcoins,
                                            commit_coins))
  {
    GNUNET_break (0);
    GNUNET_free (commit_coins);
    return (MHD_YES == TMH_RESPONSE_reply_internal_db_error (connection))
        ? GNUNET_NO : GNUNET_SYSERR;
  }

  for (j = 0; j < num_newcoins; j++)
  {
    struct TALER_RefreshLinkDecrypted *link_data;
    struct TALER_CoinSpendPublicKeyP coin_pub;
    struct GNUNET_HashCode h_msg;
    char *buf;
    size_t buf_len;

    link_data = TALER_refresh_decrypt (commit_coins[j].refresh_link,
                                       &last_shared_secret);
    if (NULL == link_data)
    {
      GNUNET_break (0);
      GNUNET_free (commit_coins);
      return (MHD_YES == TMH_RESPONSE_reply_internal_error (connection,
                                                            "Decryption error"))
          ? GNUNET_NO : GNUNET_SYSERR;
    }

    GNUNET_CRYPTO_eddsa_key_get_public (&link_data->coin_priv.eddsa_priv,
                                        &coin_pub.eddsa_pub);
    GNUNET_CRYPTO_hash (&coin_pub,
                        sizeof (struct TALER_CoinSpendPublicKeyP),
                        &h_msg);
    if (0 == (buf_len =
              GNUNET_CRYPTO_rsa_blind (&h_msg,
                                       link_data->blinding_key.rsa_blinding_key,
                                       denom_pubs[j].rsa_public_key,
                                       &buf)))
    {
      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                  "blind failed\n");
      GNUNET_free (commit_coins);
      return (MHD_YES == TMH_RESPONSE_reply_internal_error (connection,
                                                            "Blinding error"))
          ? GNUNET_NO : GNUNET_SYSERR;
    }

    if ( (buf_len != commit_coins[j].coin_ev_size) ||
         (0 != memcmp (buf,
                       commit_coins[j].coin_ev,
                       buf_len)) )
    {
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  "blind envelope does not match for k=%u, old=%d\n",
                  off,
                  (int) j);
      GNUNET_free (commit_coins);
      return send_melt_commitment_error (connection,
                                         session,
                                         session_hash,
                                         off,
                                         j,
                                         "envelope");
    }
    GNUNET_free (buf);
  }
  GNUNET_free (commit_coins);

  return GNUNET_OK;
}


/**
 * Mint a coin as part of a refresh operation.  Obtains the
 * envelope from the database and performs the signing operation.
 *
 * @param connection the MHD connection to handle
 * @param session database connection to use
 * @param session_hash hash of session to query
 * @param key_state key state to lookup denomination pubs
 * @param denom_pub denomination key for the coin to create
 * @param commit_coin the coin that was committed
 * @param coin_off number of the coin
 * @return NULL on error, otherwise signature over the coin
 */
static struct TALER_DenominationSignature
refresh_mint_coin (struct MHD_Connection *connection,
                   struct TALER_MINTDB_Session *session,
                   const struct GNUNET_HashCode *session_hash,
                   struct TMH_KS_StateHandle *key_state,
                   const struct TALER_DenominationPublicKey *denom_pub,
                   const struct TALER_MINTDB_RefreshCommitCoin *commit_coin,
                   unsigned int coin_off)
{
  struct TALER_MINTDB_DenominationKeyIssueInformation *dki;
  struct TALER_DenominationSignature ev_sig;

  dki = TMH_KS_denomination_key_lookup (key_state,
                                        denom_pub,
					TMH_KS_DKU_WITHDRAW);
  if (NULL == dki)
  {
    GNUNET_break (0);
    ev_sig.rsa_signature = NULL;
    return ev_sig;
  }
  ev_sig.rsa_signature
      = GNUNET_CRYPTO_rsa_sign (dki->denom_priv.rsa_private_key,
                                commit_coin->coin_ev,
                                commit_coin->coin_ev_size);
  if (NULL == ev_sig.rsa_signature)
  {
    GNUNET_break (0);
    return ev_sig;
  }
  if (GNUNET_OK !=
      TMH_plugin->insert_refresh_out (TMH_plugin->cls,
                                      session,
                                      session_hash,
                                      coin_off,
                                      &ev_sig))
  {
    GNUNET_break (0);
    GNUNET_CRYPTO_rsa_signature_free (ev_sig.rsa_signature);
    ev_sig.rsa_signature = NULL;
  }
  return ev_sig;
}


/**
 * The client request was well-formed, now execute the DB transaction
 * of a "/refresh/reveal" operation.  We use the @a ev_sigs and
 * @a commit_coins to clean up resources after this function returns
 * as we might experience retries of the database transaction.
 *
 * @param connection the MHD connection to handle
 * @param session database session
 * @param session_hash hash identifying the refresh session
 * @param refresh_session information about the refresh operation we are doing
 * @param denom_pubs array of "num_newcoins" denomination keys for the new coins
 * @param ev_sigs[out] where to store generated signatures for the new coins,
 *                     array of length "num_newcoins", memory released by the
 *                     caller
 * @param commit_coins[out] array of length "num_newcoins" to be used for
 *                     information about the new coins from the commitment.
 * @return MHD result code
 */
static int
execute_refresh_reveal_transaction (struct MHD_Connection *connection,
                                    struct TALER_MINTDB_Session *session,
                                    const struct GNUNET_HashCode *session_hash,
                                    struct TALER_MINTDB_RefreshSession *refresh_session,
                                    struct TALER_MINTDB_RefreshMelt *melts,
                                    struct TALER_DenominationPublicKey *denom_pubs,
                                    struct TALER_DenominationSignature *ev_sigs,
                                    struct TALER_MINTDB_RefreshCommitCoin *commit_coins)
{
  unsigned int j;
  struct TMH_KS_StateHandle *key_state;

  START_TRANSACTION (session, connection);
  if (GNUNET_OK !=
      TMH_plugin->get_refresh_commit_coins (TMH_plugin->cls,
                                            session,
                                            session_hash,
                                            refresh_session->noreveal_index,
                                            refresh_session->num_newcoins,
                                            commit_coins))
  {
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }
  key_state = TMH_KS_acquire ();
  for (j=0;j<refresh_session->num_newcoins;j++)
  {
    if (NULL == ev_sigs[j].rsa_signature) /* could be non-NULL during retries */
      ev_sigs[j] = refresh_mint_coin (connection,
                                      session,
                                      session_hash,
                                      key_state,
                                      &denom_pubs[j],
                                      &commit_coins[j],
                                      j);
    if (NULL == ev_sigs[j].rsa_signature)
    {
      TMH_KS_release (key_state);
      return TMH_RESPONSE_reply_internal_db_error (connection);
    }
  }
  TMH_KS_release (key_state);
  COMMIT_TRANSACTION (session, connection);
  return TMH_RESPONSE_reply_refresh_reveal_success (connection,
                                                    refresh_session->num_newcoins,
                                                    ev_sigs);
}


/**
 * Execute a "/refresh/reveal".  The client is revealing to us the
 * transfer keys for @a #TALER_CNC_KAPPA-1 sets of coins.  Verify that the
 * revealed transfer keys would allow linkage to the blinded coins,
 * and if so, return the signed coins for corresponding to the set of
 * coins that was not chosen.
 *
 * @param connection the MHD connection to handle
 * @param session_hash hash identifying the refresh session
 * @param num_oldcoins size of y-dimension of @a transfer_privs array
 * @param transfer_privs array with the revealed transfer keys,
 *                      x-dimension must be #TALER_CNC_KAPPA - 1
 * @return MHD result code
 */
int
TMH_DB_execute_refresh_reveal (struct MHD_Connection *connection,
                               const struct GNUNET_HashCode *session_hash,
                               unsigned int num_oldcoins,
                               struct TALER_TransferPrivateKeyP **transfer_privs)
{
  int res;
  struct TALER_MINTDB_Session *session;
  struct TALER_MINTDB_RefreshSession refresh_session;
  struct TALER_MINTDB_RefreshMelt *melts;
  struct TALER_DenominationPublicKey *denom_pubs;
  struct TALER_DenominationSignature *ev_sigs;
  struct TALER_MINTDB_RefreshCommitCoin *commit_coins;
  unsigned int i;
  unsigned int j;
  unsigned int off;

  if (NULL == (session = TMH_plugin->get_session (TMH_plugin->cls,
                                                  TMH_test_mode)))
  {
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }

  res = TMH_plugin->get_refresh_session (TMH_plugin->cls,
                                         session,
                                         session_hash,
                                         &refresh_session);
  if (GNUNET_NO == res)
    return TMH_RESPONSE_reply_arg_invalid (connection,
                                           "session_hash");
  if (GNUNET_SYSERR == res)
    return TMH_RESPONSE_reply_internal_db_error (connection);
  if (0 == refresh_session.num_oldcoins)
  {
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }

  melts = GNUNET_malloc (refresh_session.num_oldcoins *
                         sizeof (struct TALER_MINTDB_RefreshMelt));
  for (j=0;j<refresh_session.num_oldcoins;j++)
  {
    if (GNUNET_OK !=
        TMH_plugin->get_refresh_melt (TMH_plugin->cls,
                                      session,
                                      session_hash,
                                      j,
                                      &melts[j]))
    {
      GNUNET_break (0);
      for (i=0;i<j;i++)
      {
        GNUNET_CRYPTO_rsa_signature_free (melts[i].coin.denom_sig.rsa_signature);
        GNUNET_CRYPTO_rsa_public_key_free (melts[i].coin.denom_pub.rsa_public_key);
      }
      GNUNET_free (melts);
      return TMH_RESPONSE_reply_internal_db_error (connection);
    }
  }
  denom_pubs = GNUNET_malloc (refresh_session.num_newcoins *
                              sizeof (struct TALER_DenominationPublicKey));
  if (GNUNET_OK !=
      TMH_plugin->get_refresh_order (TMH_plugin->cls,
                                     session,
                                     session_hash,
                                     refresh_session.num_newcoins,
                                     denom_pubs))
  {
    GNUNET_break (0);
    GNUNET_free (denom_pubs);
    for (i=0;i<refresh_session.num_oldcoins;i++)
    {
      GNUNET_CRYPTO_rsa_signature_free (melts[i].coin.denom_sig.rsa_signature);
      GNUNET_CRYPTO_rsa_public_key_free (melts[i].coin.denom_pub.rsa_public_key);
    }
    GNUNET_free (melts);
    return (MHD_YES == TMH_RESPONSE_reply_internal_db_error (connection))
        ? GNUNET_NO : GNUNET_SYSERR;
  }


  off = 0;
  for (i=0;i<TALER_CNC_KAPPA - 1;i++)
  {
    if (i == refresh_session.noreveal_index)
      off = 1;
    if (GNUNET_OK !=
        (res = check_commitment (connection,
                                 session,
                                 session_hash,
                                 i + off,
                                 refresh_session.num_oldcoins,
                                 transfer_privs[i],
                                 melts,
                                 refresh_session.num_newcoins,
                                 denom_pubs)))
    {
      for (j=0;j<refresh_session.num_newcoins;j++)
        GNUNET_CRYPTO_rsa_public_key_free (denom_pubs[j].rsa_public_key);
      GNUNET_free (denom_pubs);
      for (i=0;i<refresh_session.num_oldcoins;i++)
      {
        GNUNET_CRYPTO_rsa_signature_free (melts[i].coin.denom_sig.rsa_signature);
        GNUNET_CRYPTO_rsa_public_key_free (melts[i].coin.denom_pub.rsa_public_key);
      }
      GNUNET_free (melts);
      return (GNUNET_NO == res) ? MHD_YES : MHD_NO;
    }
  }
  for (i=0;i<refresh_session.num_oldcoins;i++)
  {
    GNUNET_CRYPTO_rsa_signature_free (melts[i].coin.denom_sig.rsa_signature);
    GNUNET_CRYPTO_rsa_public_key_free (melts[i].coin.denom_pub.rsa_public_key);
  }
  GNUNET_free (melts);

  /* Client request OK, start transaction */
  commit_coins = GNUNET_malloc (refresh_session.num_newcoins *
                                sizeof (struct TALER_MINTDB_RefreshCommitCoin));
  ev_sigs = GNUNET_malloc (refresh_session.num_newcoins *
                           sizeof (struct TALER_DenominationSignature));
  res = execute_refresh_reveal_transaction (connection,
                                            session,
                                            session_hash,
                                            &refresh_session,
                                            melts,
                                            denom_pubs,
                                            ev_sigs,
                                            commit_coins);
  for (i=0;i<refresh_session.num_newcoins;i++)
    if (NULL != ev_sigs[i].rsa_signature)
    GNUNET_CRYPTO_rsa_signature_free (ev_sigs[i].rsa_signature);
  for (j=0;j<refresh_session.num_newcoins;j++)
    if (NULL != denom_pubs[j].rsa_public_key)
      GNUNET_CRYPTO_rsa_public_key_free (denom_pubs[j].rsa_public_key);
  GNUNET_free (ev_sigs);
  GNUNET_free (denom_pubs);
  GNUNET_free (commit_coins);
  return res;
}


/**
 * Closure for #handle_transfer_data().
 */
struct HTD_Context
{

  /**
   * Session link data we collect.
   */
  struct TMH_RESPONSE_LinkSessionInfo *sessions;

  /**
   * Database session. Nothing to do with @a sessions.
   */
  struct TALER_MINTDB_Session *session;

  /**
   * MHD connection, for queueing replies.
   */
  struct MHD_Connection *connection;

  /**
   * Number of sessions the coin was melted into.
   */
  unsigned int num_sessions;

  /**
   * How are we expected to proceed. #GNUNET_SYSERR if we
   * failed to return an error (should return #MHD_NO).
   * #GNUNET_NO if we succeeded in queueing an MHD error
   * (should return #MHD_YES from #TMH_execute_refresh_link),
   * #GNUNET_OK if we should call #TMH_RESPONSE_reply_refresh_link_success().
   */
  int status;
};


/**
 * Function called with the session hashes and transfer secret
 * information for a given coin.  Gets the linkage data and
 * builds the reply for the client.
 *
 *
 * @param cls closure, a `struct HTD_Context`
 * @param session_hash a session the coin was melted in
 * @param transfer_pub public transfer key for the session
 * @param shared_secret_enc set to shared secret for the session
 */
static void
handle_transfer_data (void *cls,
                      const struct GNUNET_HashCode *session_hash,
                      const struct TALER_TransferPublicKeyP *transfer_pub,
                      const struct TALER_EncryptedLinkSecretP *shared_secret_enc)
{
  struct HTD_Context *ctx = cls;
  struct TALER_MINTDB_LinkDataList *ldl;
  struct TMH_RESPONSE_LinkSessionInfo *lsi;

  if (GNUNET_OK != ctx->status)
    return;
  ldl = TMH_plugin->get_link_data_list (TMH_plugin->cls,
                                        ctx->session,
                                        session_hash);
  if (NULL == ldl)
  {
    ctx->status = GNUNET_NO;
    if (MHD_NO ==
        TMH_RESPONSE_reply_json_pack (ctx->connection,
                                      MHD_HTTP_NOT_FOUND,
                                      "{s:s}",
                                      "error",
                                      "link data not found (link)"))
      ctx->status = GNUNET_SYSERR;
    return;
  }
  GNUNET_array_grow (ctx->sessions,
                     ctx->num_sessions,
                     ctx->num_sessions + 1);
  lsi = &ctx->sessions[ctx->num_sessions - 1];
  lsi->transfer_pub = *transfer_pub;
  lsi->shared_secret_enc = *shared_secret_enc;
  lsi->ldl = ldl;
}


/**
 * Execute a "/refresh/link".  Returns the linkage information that
 * will allow the owner of a coin to follow the refresh trail to
 * the refreshed coin.
 *
 * @param connection the MHD connection to handle
 * @param coin_pub public key of the coin to link
 * @return MHD result code
 */
int
TMH_DB_execute_refresh_link (struct MHD_Connection *connection,
                             const struct TALER_CoinSpendPublicKeyP *coin_pub)
{
  struct HTD_Context ctx;
  int res;
  unsigned int i;

  if (NULL == (ctx.session = TMH_plugin->get_session (TMH_plugin->cls,
                                                      TMH_test_mode)))
  {
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }
  ctx.connection = connection;
  ctx.num_sessions = 0;
  ctx.sessions = NULL;
  ctx.status = GNUNET_OK;
  res = TMH_plugin->get_transfer (TMH_plugin->cls,
                                  ctx.session,
                                  coin_pub,
                                  &handle_transfer_data,
                                  &ctx);
  if (GNUNET_SYSERR == ctx.status)
  {
    res = MHD_NO;
    goto cleanup;
  }
  if (GNUNET_NO == ctx.status)
  {
    res = MHD_YES;
    goto cleanup;
  }
  GNUNET_assert (GNUNET_OK == ctx.status);
  if (0 == ctx.num_sessions)
    return TMH_RESPONSE_reply_arg_unknown (connection,
                                           "coin_pub");
  res = TMH_RESPONSE_reply_refresh_link_success (connection,
                                                 ctx.num_sessions,
                                                 ctx.sessions);
 cleanup:
  for (i=0;i<ctx.num_sessions;i++)
    TMH_plugin->free_link_data_list (TMH_plugin->cls,
                                     ctx.sessions[i].ldl);
  GNUNET_free_non_null (ctx.sessions);
  return res;
}


/**
 * Add an incoming transaction to the database.  Checks if the
 * transaction is fresh (not a duplicate) and if so adds it to
 * the database.
 *
 * @param connection the MHD connection to handle
 * @param reserve_pub public key of the reserve
 * @param amount amount to add to the reserve
 * @param execution_time when did we receive the wire transfer
 * @param wire details about the wire transfer
 * @return MHD result code
 */
int
TMH_DB_execute_admin_add_incoming (struct MHD_Connection *connection,
                                   const struct TALER_ReservePublicKeyP *reserve_pub,
                                   const struct TALER_Amount *amount,
                                   struct GNUNET_TIME_Absolute execution_time,
                                   json_t *wire)
{
  struct TALER_MINTDB_Session *session;
  int ret;

  if (NULL == (session = TMH_plugin->get_session (TMH_plugin->cls,
                                                  TMH_test_mode)))
  {
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }
  ret = TMH_plugin->reserves_in_insert (TMH_plugin->cls,
                                        session,
                                        reserve_pub,
                                        amount,
                                        execution_time,
                                        wire);
  if (GNUNET_SYSERR == ret)
  {
    GNUNET_break (0);
    return TMH_RESPONSE_reply_internal_db_error (connection);
  }
  return TMH_RESPONSE_reply_json_pack (connection,
                                       MHD_HTTP_OK,
                                       "{s:s}",
                                       "status",
                                       (GNUNET_OK == ret)
                                       ? "NEW"
                                       : "DUP");
}


/* end of taler-mint-httpd_db.c */