summaryrefslogtreecommitdiff
path: root/src/backend/taler-merchant-httpd_private-get-orders-ID.c
blob: 829b3a568e4200dac9d3b7258f8ca0c170d6a1b3 (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
/*
  This file is part of TALER
  (C) 2017, 2019, 2020 Taler Systems SA

  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, see <http://www.gnu.org/licenses/>
*/
/**
 * @file backend/taler-merchant-httpd_private-get-orders-ID.c
 * @brief implementation of GET /private/orders/ID handler
 * @author Florian Dold
 * @author Christian Grothoff
 */
#include "platform.h"
#include "taler-merchant-httpd_private-get-orders-ID.h"
#include "taler-merchant-httpd_get-orders-ID.h"
#include <taler/taler_json_lib.h>
#include "taler-merchant-httpd_mhd.h"
#include "taler-merchant-httpd_exchanges.h"
#include "taler-merchant-httpd_private-get-orders.h"


/**
 * How long do we wait on the exchange?
 */
#define EXCHANGE_TIMEOUT GNUNET_TIME_relative_multiply ( \
    GNUNET_TIME_UNIT_SECONDS, 30)


/**
 * Data structure we keep for a check payment request.
 */
struct GetOrderRequestContext;


/**
 * Request to an exchange for details about wire transfers
 * in response to a coin's deposit operation.
 */
struct TransferQuery
{

  /**
   * Kept in a DLL.
   */
  struct TransferQuery *next;

  /**
   * Kept in a DLL.
   */
  struct TransferQuery *prev;

  /**
   * Handle to query exchange about deposit status.
   */
  struct TALER_EXCHANGE_DepositGetHandle *dgh;

  /**
   * Handle for ongoing exchange operation.
   */
  struct TMH_EXCHANGES_FindOperation *fo;

  /**
   * Overall request this TQ belongs with.
   */
  struct GetOrderRequestContext *gorc;

  /**
   * Hash of the merchant's bank account the transfer (presumably) went to.
   */
  struct GNUNET_HashCode h_wire;

  /**
   * Value deposited (including deposit fee).
   */
  struct TALER_Amount amount_with_fee;

  /**
   * Deposit fee paid for this coin.
   */
  struct TALER_Amount deposit_fee;

  /**
   * Public key of the coin this is about.
   */
  struct TALER_CoinSpendPublicKeyP coin_pub;

  /**
   * Which deposit operation is this about?
   */
  uint64_t deposit_serial;

};


/**
 * Data structure we keep for a check payment request.
 */
struct GetOrderRequestContext
{

  /**
   * Entry in the #resume_timeout_heap for this check payment, if we are
   * suspended.
   */
  struct TMH_SuspendedConnection sc;

  /**
   * Which merchant instance is this for?
   */
  struct TMH_HandlerContext *hc;

  /**
   * session of the client
   */
  const char *session_id;

  /**
   * Fulfillment URL extracted from the contract. For repurchase detection.
   * Only valid as long as @e contract_terms is valid!  NULL if there is
   * no fulfillment URL in the contract.
   */
  const char *fulfillment_url;

  /**
   * Kept in a DLL while suspended on exchange.
   */
  struct GetOrderRequestContext *next;

  /**
   * Kept in a DLL while suspended on exchange.
   */
  struct GetOrderRequestContext *prev;

  /**
   * Handle to the exchange, only valid while the @e fo succeeds.
   */
  struct TALER_EXCHANGE_Handle *eh;

  /**
   * Head of DLL of individual queries for transfer data.
   */
  struct TransferQuery *tq_head;

  /**
   * Tail of DLL of individual queries for transfer data.
   */
  struct TransferQuery *tq_tail;

  /**
   * Timeout task while waiting on exchange.
   */
  struct GNUNET_SCHEDULER_Task *tt;

  /**
   * Contract terms of the payment we are checking. NULL when they
   * are not (yet) known.
   */
  json_t *contract_terms;

  /**
   * Wire details for the payment, to be returned in the reply. NULL
   * if not available.
   */
  json_t *wire_details;

  /**
   * Problems we encountered when looking up Wire details
   * for the payment, to be returned.  NULL if not available.
   */
  json_t *wire_reports;

  /**
   * Details about refunds, NULL if there are no refunds.
   */
  json_t *refund_details;

  /**
   * Hash over the @e contract_terms.
   */
  struct GNUNET_HashCode h_contract_terms;

  /**
   * Total amount the exchange deposited into our bank account
   * (confirmed or unconfirmed), excluding fees.
   */
  struct TALER_Amount deposits_total;

  /**
   * Total amount in deposit fees we paid for all coins.
   */
  struct TALER_Amount deposit_fees_total;

  /**
   * Total value of the coins that the exchange deposited into our bank
   * account (confirmed or unconfirmed), including deposit fees.
   */
  struct TALER_Amount value_total;

  /**
   * Total we were to be paid under the contract, excluding refunds.
   */
  struct TALER_Amount contract_amount;

  /**
   * Serial ID of the order.
   */
  uint64_t order_serial;

  /**
   * Total refunds granted for this payment. Only initialized
   * if @e refunded is set to true.
   */
  struct TALER_Amount refund_amount;

  /**
   * Exchange HTTP error code encountered while trying to determine wire transfer
   * details. #TALER_EC_NONE for no error encountered.
   */
  unsigned int exchange_hc;

  /**
   * Exchange error code encountered while trying to determine wire transfer
   * details. #TALER_EC_NONE for no error encountered.
   */
  enum TALER_ErrorCode exchange_ec;

  /**
   * Error code encountered while trying to determine wire transfer
   * details. #TALER_EC_NONE for no error encountered.
   */
  enum TALER_ErrorCode wire_ec;

  /**
   * HTTP status to return with @e wire_ec, 0 if @e wire_ec is #TALER_EC_NONE.
   */
  unsigned int wire_hc;

  /**
   * Set to true if this payment has been refunded and
   * @e refund_amount is initialized.
   */
  bool refunded;

  /**
   * Did the client request us to fetch the wire transfer status?
   * If false, we may still return it if it is available.
   */
  bool transfer_status_requested;

};


/**
 * Head of list of suspended requests waiting on the exchange.
 */
static struct GetOrderRequestContext *gorc_head;

/**
 * Tail of list of suspended requests waiting on the exchange.
 */
static struct GetOrderRequestContext *gorc_tail;


/**
 * Resume processing the request, cancelling all pending asynchronous
 * operations.
 *
 * @param gorc request to resume
 * @param http_status HTTP status to return, 0 to continue with success
 * @param ec error code for the request, #TALER_EC_NONE on success
 */
static void
gorc_resume (struct GetOrderRequestContext *gorc,
             unsigned int http_status,
             enum TALER_ErrorCode ec)
{
  struct TransferQuery *tq;

  if (NULL != gorc->tt)
  {
    GNUNET_SCHEDULER_cancel (gorc->tt);
    gorc->tt = NULL;
  }
  while (NULL != (tq = gorc->tq_head))
  {
    if (NULL != tq->fo)
    {
      TMH_EXCHANGES_find_exchange_cancel (tq->fo);
      tq->fo = NULL;
    }
    if (NULL != tq->dgh)
    {
      TALER_EXCHANGE_deposits_get_cancel (tq->dgh);
      tq->dgh = NULL;
    }
  }
  gorc->wire_hc = http_status;
  gorc->wire_ec = ec;
  GNUNET_CONTAINER_DLL_remove (gorc_head,
                               gorc_tail,
                               gorc);
  MHD_resume_connection (gorc->sc.con);
  TMH_trigger_daemon ();   /* we resumed, kick MHD */
}


/**
 * Add a report about trouble obtaining wire transfer data to the reply.
 *
 * @param gorc request to add wire report to
 * @param ec error code to add
 * @param coin_pub public key of the affected coin
 * @param exchange_hr details from exchange, NULL if exchange is blameless
 */
static void
gorc_report (struct GetOrderRequestContext *gorc,
             enum TALER_ErrorCode ec,
             struct TALER_CoinSpendPublicKeyP *coin_pub,
             const struct TALER_EXCHANGE_HttpResponse *exchange_hr)
{
  if (NULL != exchange_hr)
    GNUNET_assert (0 ==
                   json_array_append_new (
                     gorc->wire_reports,
                     json_pack ("{s:I, s:s, s:I, s:I, s:o }",
                                "code",
                                (json_int_t) ec,
                                "hint",
                                TALER_ErrorCode_get_hint (ec),
                                "exchange_ec",
                                (json_int_t) exchange_hr->ec,
                                "exchange_hc",
                                (json_int_t) exchange_hr->http_status,
                                "coin_pub",
                                GNUNET_JSON_from_data_auto (coin_pub))));
  else
    GNUNET_assert (0 ==
                   json_array_append_new (
                     gorc->wire_reports,
                     json_pack ("{s:I, s:s, s:o }",
                                "code",
                                (json_int_t) ec,
                                "hint",
                                TALER_ErrorCode_get_hint (ec),
                                "coin_pub",
                                GNUNET_JSON_from_data_auto (coin_pub))));
}


/**
 * Timeout trying to get current wire transfer data from the exchange.
 * Clean up and continue.
 *
 * @param cls closure, must be a `struct GetOrderRequestContext *`
 */
static void
exchange_timeout_cb (void *cls)
{
  struct GetOrderRequestContext *gorc = cls;

  gorc->tt = NULL;
  gorc_resume (gorc,
               MHD_HTTP_REQUEST_TIMEOUT,
               TALER_EC_GET_ORDERS_EXCHANGE_TIMEOUT);
}


/**
 * Function called with detailed wire transfer data.
 *
 * @param cls closure with a `struct TransferQuery *`
 * @param hr HTTP response data
 * @param dd details about the deposit (NULL on errors)
 */
static void
deposit_get_cb (void *cls,
                const struct TALER_EXCHANGE_HttpResponse *hr,
                const struct TALER_EXCHANGE_DepositData *dd)
{
  struct TransferQuery *tq = cls;
  struct GetOrderRequestContext *gorc = tq->gorc;

  GNUNET_CONTAINER_DLL_remove (gorc->tq_head,
                               gorc->tq_tail,
                               tq);
  if (NULL == dd)
  {
    gorc_report (gorc,
                 TALER_EC_GET_ORDERS_EXCHANGE_TRACKING_FAILURE,
                 &tq->coin_pub,
                 hr);
    GNUNET_free (tq);
    if (NULL == gorc->tq_head)
      gorc_resume (gorc,
                   0,
                   TALER_EC_NONE);
    return;
  }
  else if (MHD_HTTP_OK == hr->http_status)
  {
    enum GNUNET_DB_QueryStatus qs;

    qs = TMH_db->insert_deposit_to_transfer (TMH_db->cls,
                                             tq->deposit_serial,
                                             dd);
    if (qs < 0)
    {
      gorc_report (gorc,
                   TALER_EC_GET_ORDERS_DB_STORE_TRACKING_FAILURE,
                   &tq->coin_pub,
                   NULL);
      GNUNET_free (tq);
      if (NULL == gorc->tq_head)
        gorc_resume (gorc,
                     0,
                     TALER_EC_NONE);
      return;
    }
    /* Compute total amount *wired* */
    if (0 >
        TALER_amount_add (&gorc->deposits_total,
                          &gorc->deposits_total,
                          &dd->coin_contribution))
    {
      gorc_report (gorc,
                   TALER_EC_GET_ORDERS_AMOUNT_ARITHMETIC_FAILURE,
                   &tq->coin_pub,
                   NULL);
      GNUNET_free (tq);
      if (NULL == gorc->tq_head)
        gorc_resume (gorc,
                     0,
                     TALER_EC_NONE);
      return;
    }
    if (0 >
        TALER_amount_add (&gorc->deposit_fees_total,
                          &gorc->deposit_fees_total,
                          &tq->deposit_fee))
    {
      gorc_report (gorc,
                   TALER_EC_GET_ORDERS_AMOUNT_ARITHMETIC_FAILURE,
                   &tq->coin_pub,
                   NULL);
      GNUNET_free (tq);
      if (NULL == gorc->tq_head)
        gorc_resume (gorc,
                     0,
                     TALER_EC_NONE);
      return;
    }
  }
  else
  {
    /* got a 'preliminary' reply from the exchange, simply skip */
    gorc_report (gorc,
                 TALER_EC_NONE,
                 &tq->coin_pub,
                 hr);
  }
  GNUNET_free (tq);
  if (NULL != gorc->tq_head)
    return;
  /* *all* are done, resume! */
  gorc_resume (gorc,
               0,
               TALER_EC_NONE);
}


/**
 * Function called with the result of a #TMH_EXCHANGES_find_exchange()
 * operation.
 *
 * @param cls closure with a `struct GetOrderRequestContext *`
 * @param hr HTTP response details
 * @param eh handle to the exchange context
 * @param payto_uri payto://-URI of the exchange
 * @param wire_fee current applicable wire fee for dealing with @a eh, NULL if not available
 * @param exchange_trusted true if this exchange is trusted by config
 */
static void
exchange_found_cb (void *cls,
                   const struct TALER_EXCHANGE_HttpResponse *hr,
                   struct TALER_EXCHANGE_Handle *eh,
                   const char *payto_uri,
                   const struct TALER_Amount *wire_fee,
                   bool exchange_trusted)
{
  struct TransferQuery *tq = cls;
  struct GetOrderRequestContext *gorc = tq->gorc;

  tq->fo = NULL;
  if (NULL == eh)
  {
    /* failed */
    GNUNET_CONTAINER_DLL_remove (gorc->tq_head,
                                 gorc->tq_tail,
                                 tq);
    GNUNET_free (tq);
    gorc->exchange_hc = hr->http_status;
    gorc->exchange_ec = hr->ec;
    gorc_resume (gorc,
                 MHD_HTTP_FAILED_DEPENDENCY,
                 TALER_EC_GET_ORDERS_EXCHANGE_LOOKUP_FAILURE);
    return;
  }
  tq->dgh = TALER_EXCHANGE_deposits_get (eh,
                                         &gorc->hc->instance->merchant_priv,
                                         &tq->h_wire,
                                         &gorc->h_contract_terms,
                                         &tq->coin_pub,
                                         &deposit_get_cb,
                                         tq);
  if (NULL == tq->dgh)
  {
    GNUNET_CONTAINER_DLL_remove (gorc->tq_head,
                                 gorc->tq_tail,
                                 tq);
    GNUNET_free (tq);
    gorc_resume (gorc,
                 MHD_HTTP_INTERNAL_SERVER_ERROR,
                 TALER_EC_GET_ORDERS_EXCHANGE_REQUEST_FAILURE);
  }
}


/**
 * Function called with each @a coin_pub that was deposited into the
 * @a h_wire account of the merchant for the @a deposit_serial as part
 * of the payment for the order identified by @a cls.
 *
 * Queries the exchange for the payment status associated with the
 * given coin.
 *
 * @param cls a `struct GetOrderRequestContext`
 * @param deposit_serial identifies the deposit operation
 * @param exchange_url URL of the exchange that issued @a coin_pub
 * @param amount_with_fee amount the exchange will deposit for this coin
 * @param deposit_fee fee the exchange will charge for this coin
 * @param h_wire hash of the merchant's wire account into which the deposit was made
 * @param coin_pub public key of the deposited coin
 */
static void
deposit_cb (void *cls,
            uint64_t deposit_serial,
            const char *exchange_url,
            const struct GNUNET_HashCode *h_wire,
            const struct TALER_Amount *amount_with_fee,
            const struct TALER_Amount *deposit_fee,
            const struct TALER_CoinSpendPublicKeyP *coin_pub)
{
  struct GetOrderRequestContext *gorc = cls;
  struct TransferQuery *tq;

  tq = GNUNET_new (struct TransferQuery);
  tq->gorc = gorc;
  tq->deposit_serial = deposit_serial;
  GNUNET_CONTAINER_DLL_insert (gorc->tq_head,
                               gorc->tq_tail,
                               tq);
  tq->coin_pub = *coin_pub;
  tq->h_wire = *h_wire;
  tq->amount_with_fee = *amount_with_fee;
  tq->deposit_fee = *deposit_fee;
  tq->fo = TMH_EXCHANGES_find_exchange (exchange_url,
                                        NULL,
                                        GNUNET_NO,
                                        &exchange_found_cb,
                                        tq);
  if (NULL == tq->fo)
  {
    gorc_resume (gorc,
                 MHD_HTTP_INTERNAL_SERVER_ERROR,
                 TALER_EC_GET_ORDERS_EXCHANGE_LOOKUP_START_FAILURE);
  }
}


/**
 * Clean up the session state for a GET /private/order/ID request.
 *
 * @param cls closure, must be a `struct GetOrderRequestContext *`
 */
static void
gorc_cleanup (void *cls)
{
  struct GetOrderRequestContext *gorc = cls;

  if (NULL != gorc->contract_terms)
    json_decref (gorc->contract_terms);
  if (NULL != gorc->wire_details)
    json_decref (gorc->wire_details);
  if (NULL != gorc->refund_details)
    json_decref (gorc->refund_details);
  if (NULL != gorc->wire_reports)
    json_decref (gorc->wire_reports);
  GNUNET_assert (NULL == gorc->tt);
  GNUNET_free (gorc);
}


/**
 * Function called with information about a refund.
 * It is responsible for summing up the refund amount.
 *
 * @param cls closure
 * @param refund_serial unique serial number of the refund
 * @param timestamp time of the refund (for grouping of refunds in the wallet UI)
 * @param coin_pub public coin from which the refund comes from
 * @param exchange_url URL of the exchange that issued @a coin_pub
 * @param rtransaction_id identificator of the refund
 * @param reason human-readable explanation of the refund
 * @param timestamp when was the refund made
 * @param refund_amount refund amount which is being taken from @a coin_pub
 * @param pending true if the this refund was not yet processed by the wallet/exchange
 */
static void
process_refunds_cb (void *cls,
                    uint64_t refund_serial,
                    struct GNUNET_TIME_Absolute timestamp,
                    const struct TALER_CoinSpendPublicKeyP *coin_pub,
                    const char *exchange_url,
                    uint64_t rtransaction_id,
                    const char *reason,
                    const struct TALER_Amount *refund_amount,
                    bool pending)
{
  struct GetOrderRequestContext *gorc = cls;

  GNUNET_assert (0 ==
                 json_array_append_new (
                   gorc->refund_details,
                   json_pack ("{s:o, s:o, s:s}",
                              "amount",
                              TALER_JSON_from_amount (refund_amount),
                              "timestamp",
                              GNUNET_JSON_from_time_abs (timestamp),
                              "reason",
                              reason)));
  /* For refunded coins, we are not charged deposit fees, so subtract those
     again */
  for (struct TransferQuery *tq = gorc->tq_head;
       NULL != tq;
       tq = tq->next)
  {
    if (0 ==
        GNUNET_memcmp (&tq->coin_pub,
                       coin_pub))
    {
      GNUNET_assert (0 <=
                     TALER_amount_subtract (&gorc->deposit_fees_total,
                                            &gorc->deposit_fees_total,
                                            &tq->deposit_fee));
    }
  }
  GNUNET_assert (0 <=
                 TALER_amount_add (&gorc->refund_amount,
                                   &gorc->refund_amount,
                                   refund_amount));
  gorc->refunded = true;
}


/**
 * Function called with available wire details, to be added to
 * the response.
 *
 * @param cls a `struct GetOrderRequestContext`
 * @param wtid wire transfer subject of the wire transfer for the coin
 * @param exchange_url base URL of the exchange that made the payment
 * @param execution_time when was the payment made
 * @param deposit_value contribution of the coin to the total wire transfer value
 * @param deposit_fee deposit fee charged by the exchange for the coin
 * @param transfer_confirmed did the merchant confirm that a wire transfer with
 *        @a wtid over the total amount happened?
 */
static void
process_transfer_details (void *cls,
                          const struct TALER_WireTransferIdentifierRawP *wtid,
                          const char *exchange_url,
                          struct GNUNET_TIME_Absolute execution_time,
                          const struct TALER_Amount *deposit_value,
                          const struct TALER_Amount *deposit_fee,
                          bool transfer_confirmed)
{
  struct GetOrderRequestContext *gorc = cls;
  json_t *wire_details = gorc->wire_details;
  struct TALER_Amount wired;
  struct GNUNET_TIME_Absolute execution_time_round = execution_time;

  /* Compute total amount *wired* */
  GNUNET_assert (0 <
                 TALER_amount_add (&gorc->deposits_total,
                                   &gorc->deposits_total,
                                   deposit_value));
  GNUNET_assert (0 <
                 TALER_amount_add (&gorc->deposit_fees_total,
                                   &gorc->deposit_fees_total,
                                   deposit_fee));

  GNUNET_TIME_round_abs (&execution_time_round);
  GNUNET_assert
    (0 <= TALER_amount_subtract (&wired,
                                 deposit_value,
                                 deposit_fee));
  GNUNET_assert (0 ==
                 json_array_append_new (
                   wire_details,
                   json_pack ("{s:o, s:s, s:o, s:o, s:b}",
                              "wtid",
                              GNUNET_JSON_from_data_auto (wtid),
                              "exchange_url",
                              exchange_url,
                              "amount",
                              TALER_JSON_from_amount (&wired),
                              "execution_time",
                              GNUNET_JSON_from_time_abs (execution_time_round),
                              "confirmed",
                              transfer_confirmed)));
}


/**
 * Manages a GET /private/orders/ID call, checking the status of a payment and
 * refunds and, if necessary, constructing the URL for a payment redirect URL.
 *
 * @param rh context of the handler
 * @param connection the MHD connection to handle
 * @param[in,out] hc context with further information about the request
 * @return MHD result code
 */
MHD_RESULT
TMH_private_get_orders_ID (const struct TMH_RequestHandler *rh,
                           struct MHD_Connection *connection,
                           struct TMH_HandlerContext *hc)
{
  struct GetOrderRequestContext *gorc = hc->ctx;
  enum GNUNET_DB_QueryStatus qs;
  bool paid;
  bool wired;
  bool order_only = false;
  struct TALER_ClaimTokenP claim_token = { 0 };

  if (NULL == gorc)
  {
    /* First time here, parse request and check order is known */
    GNUNET_assert (NULL != hc->infix);
    gorc = GNUNET_new (struct GetOrderRequestContext);
    hc->cc = &gorc_cleanup;
    hc->ctx = gorc;
    gorc->sc.con = connection;
    gorc->hc = hc;
    gorc->wire_details = json_array ();
    GNUNET_assert (NULL != gorc->wire_details);
    gorc->refund_details = json_array ();
    GNUNET_assert (NULL != gorc->refund_details);
    gorc->wire_reports = json_array ();
    GNUNET_assert (NULL != gorc->wire_reports);
    gorc->session_id = MHD_lookup_connection_value (connection,
                                                    MHD_GET_ARGUMENT_KIND,
                                                    "session_id");
    {
      const char *long_poll_timeout_s;

      long_poll_timeout_s = MHD_lookup_connection_value (connection,
                                                         MHD_GET_ARGUMENT_KIND,
                                                         "timeout_ms");
      if (NULL != long_poll_timeout_s)
      {
        unsigned long long timeout;

        if (1 != sscanf (long_poll_timeout_s,
                         "%llu",
                         &timeout))
        {
          GNUNET_break_op (0);
          return TALER_MHD_reply_with_error (connection,
                                             MHD_HTTP_BAD_REQUEST,
                                             TALER_EC_PARAMETER_MALFORMED,
                                             "timeout_ms must be non-negative number");
        }
        gorc->sc.long_poll_timeout
          = GNUNET_TIME_relative_to_absolute (GNUNET_TIME_relative_multiply (
                                                GNUNET_TIME_UNIT_MILLISECONDS,
                                                timeout));
      }
      else
      {
        gorc->sc.long_poll_timeout = GNUNET_TIME_UNIT_ZERO_ABS;
      }
    }

    {
      const char *transfer_s;

      transfer_s = MHD_lookup_connection_value (connection,
                                                MHD_GET_ARGUMENT_KIND,
                                                "transfer");
      if ( (NULL != transfer_s) &&
           (0 == strcasecmp (transfer_s,
                             "yes")) )
        gorc->transfer_status_requested = true;
    }
  }

  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              "Starting GET /private/orders/%s processing with timeout %s\n",
              hc->infix,
              GNUNET_STRINGS_absolute_time_to_string (
                gorc->sc.long_poll_timeout));
  if (NULL != gorc->contract_terms)
  {
    /* Clear old contract terms, might be from an earlier unclaimed contract
       and thus could have changed during claiming. */
    json_decref (gorc->contract_terms);
    gorc->contract_terms = NULL;
    gorc->fulfillment_url = NULL;
  }
  TMH_db->preflight (TMH_db->cls);
  qs = TMH_db->lookup_contract_terms (TMH_db->cls,
                                      hc->instance->settings.id,
                                      hc->infix,
                                      &gorc->contract_terms,
                                      &gorc->order_serial);
  if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
  {
    order_only = true;
  }
  if (0 > qs)
  {
    /* single, read-only SQL statements should never cause
       serialization problems */
    GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR != qs);
    /* Always report on hard error as well to enable diagnostics */
    GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR == qs);
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
                                       TALER_EC_GET_ORDERS_DB_FETCH_CONTRACT_TERMS_ERROR,
                                       NULL);
  }
  if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
  {
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_NOT_FOUND,
                                       TALER_EC_GET_ORDERS_ORDER_NOT_FOUND,
                                       hc->infix);
  }

  {
    struct GNUNET_HashCode unused;
    json_t *ct = NULL;

    /* We need the order for two cases:  Either when the contract doesn't exist yet,
     * or when the order is claimed but unpaid, and we need the claim token. */
    qs = TMH_db->lookup_order (TMH_db->cls,
                               hc->instance->settings.id,
                               hc->infix,
                               &claim_token,
                               &unused,
                               &ct);

    if (0 > qs)
    {
      /* single, read-only SQL statements should never cause
         serialization problems */
      GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR != qs);
      /* Always report on hard error as well to enable diagnostics */
      GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR == qs);
      return TALER_MHD_reply_with_error (connection,
                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                                         TALER_EC_GET_ORDERS_DB_FETCH_CONTRACT_TERMS_ERROR,
                                         NULL);
    }
    if (order_only && (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs) )
    {
      return TALER_MHD_reply_with_error (connection,
                                         MHD_HTTP_NOT_FOUND,
                                         TALER_EC_GET_ORDERS_ORDER_NOT_FOUND,
                                         hc->infix);
    }
    if (order_only)
    {
      gorc->contract_terms = ct;
    }
    else if (NULL != ct)
    {
      json_decref (ct);
    }
  }
  /* extract the fulfillment URL and total amount from the contract terms! */
  {
    struct GNUNET_JSON_Specification spec[] = {
      TALER_JSON_spec_amount ("amount",
                              &gorc->contract_amount),
      GNUNET_JSON_spec_end ()
    };

    if (GNUNET_OK !=
        GNUNET_JSON_parse (gorc->contract_terms,
                           spec,
                           NULL, NULL))
    {
      GNUNET_break (0);
      return TALER_MHD_reply_with_error (
        connection,
        MHD_HTTP_INTERNAL_SERVER_ERROR,
        TALER_EC_GET_ORDERS_DB_FETCH_CONTRACT_TERMS_ERROR,
        hc->infix);
    }
    if (0 !=
        strcasecmp (TMH_currency,
                    gorc->contract_amount.currency))
    {
      GNUNET_break (0);
      return TALER_MHD_reply_with_error (
        connection,
        MHD_HTTP_INTERNAL_SERVER_ERROR,
        TALER_EC_GET_ORDERS_DB_FETCH_CONTRACT_TERMS_ERROR,
        gorc->contract_amount.currency);
    }
  }
  gorc->fulfillment_url
    = json_string_value (json_object_get (gorc->contract_terms,
                                          "fulfillment_url"));
  if (! order_only)
  {
    if (GNUNET_OK !=
        TALER_JSON_contract_hash (gorc->contract_terms,
                                  &gorc->h_contract_terms))
    {
      GNUNET_break (0);
      return TALER_MHD_reply_with_error (connection,
                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                                         TALER_EC_GET_ORDERS_FAILED_COMPUTE_PROPOSAL_HASH,
                                         NULL);
    }
  }
  if (TALER_EC_NONE != gorc->wire_ec)
  {
    return TALER_MHD_reply_with_error (connection,
                                       gorc->wire_hc,
                                       gorc->wire_ec,
                                       NULL);
  }

  GNUNET_assert (NULL != gorc->contract_terms);

  TMH_db->preflight (TMH_db->cls);
  if (order_only)
  {
    paid = false;
    wired = false;
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Order %s unclaimed, no need to lookup payment status\n",
                hc->infix);
  }
  else
  {
    qs = TMH_db->lookup_payment_status (TMH_db->cls,
                                        gorc->order_serial,
                                        gorc->session_id,
                                        &paid,
                                        &wired);
    if (0 > qs)
    {
      /* single, read-only SQL statements should never cause
         serialization problems, and the entry should exist as per above */
      GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR == qs);
      return TALER_MHD_reply_with_error (connection,
                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                                         TALER_EC_GET_ORDERS_DB_FETCH_PAYMENT_STATUS,
                                         NULL);
    }
  }
  if ( (! paid) &&
       (NULL != gorc->fulfillment_url) &&
       (NULL != gorc->session_id) )
  {
    char *already_paid_order_id = NULL;

    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Running re-purchase detection for %s/%s\n",
                gorc->session_id,
                gorc->fulfillment_url);
    qs = TMH_db->lookup_order_by_fulfillment (TMH_db->cls,
                                              hc->instance->settings.id,
                                              gorc->fulfillment_url,
                                              gorc->session_id,
                                              &already_paid_order_id);
    if (0 > qs)
    {
      /* single, read-only SQL statements should never cause
         serialization problems, and the entry should exist as per above */
      GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR == qs);
      return TALER_MHD_reply_with_error (connection,
                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                                         TALER_EC_GET_ORDERS_DB_FETCH_PAYMENT_STATUS,
                                         NULL);
    }
    if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs)
    {
      /* User did pay for this order, but under a different session; ask wallet
         to switch order ID */
      char *taler_pay_uri;
      char *order_status_url;
      MHD_RESULT ret;

      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                  "Found already paid order %s\n",
                  already_paid_order_id);
      taler_pay_uri = TMH_make_taler_pay_uri (connection,
                                              hc->infix,
                                              gorc->session_id,
                                              hc->instance->settings.id,
                                              &claim_token);
      order_status_url = TMH_make_order_status_url (connection,
                                                    hc->infix,
                                                    gorc->session_id,
                                                    hc->instance->settings.id,
                                                    &claim_token,
                                                    NULL);
      ret = TALER_MHD_reply_json_pack (connection,
                                       MHD_HTTP_OK,
                                       "{s:s, s:s, s:s, s:s, s:s}",
                                       "taler_pay_uri",
                                       taler_pay_uri,
                                       "order_status_url",
                                       order_status_url,
                                       "order_status",
                                       "unpaid",
                                       "already_paid_order_id",
                                       already_paid_order_id,
                                       "already_paid_fulfillment_url",
                                       gorc->fulfillment_url);
      GNUNET_free (taler_pay_uri);
      GNUNET_free (already_paid_order_id);
      return ret;
    }
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "No already paid order for %s/%s\n",
                gorc->session_id,
                gorc->fulfillment_url);
  }

  if (paid &&
      (! wired) &&
      gorc->transfer_status_requested)
  {
    /* suspend connection, wait for exchange to check wire transfer status there */
    gorc->transfer_status_requested = false;   /* only try ONCE */
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_get_zero (TMH_currency,
                                          &gorc->deposits_total));
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_get_zero (TMH_currency,
                                          &gorc->deposit_fees_total));
    TMH_db->lookup_deposits_by_order (TMH_db->cls,
                                      gorc->order_serial,
                                      &deposit_cb,
                                      gorc);
    if (NULL != gorc->tq_head)
    {
      GNUNET_CONTAINER_DLL_insert (gorc_head,
                                   gorc_tail,
                                   gorc);
      gorc->tt = GNUNET_SCHEDULER_add_delayed (EXCHANGE_TIMEOUT,
                                               &exchange_timeout_cb,
                                               gorc);
      MHD_suspend_connection (connection);
      return MHD_YES;
    }
  }

  if ( (! paid) &&
       (0 != gorc->sc.long_poll_timeout.abs_value_us) )
  {
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "Suspending GET /private/orders/%s\n",
                hc->infix);
    TMH_long_poll_suspend (hc->infix,
                           gorc->session_id,
                           gorc->fulfillment_url,
                           hc->instance,
                           &gorc->sc,
                           NULL);
    return MHD_YES;
  }

  if (! paid)
  {
    /* User never paid for this order */
    char *taler_pay_uri;
    char *order_status_url;
    MHD_RESULT ret;
    struct TALER_ClaimTokenP *ct = NULL;

    /* Already claimed, so we include the claim token so that
     * the order status page will show the QR code and won't run
     * into a redirect loop. */
    if (! order_only)
      ct = &claim_token;

    taler_pay_uri = TMH_make_taler_pay_uri (connection,
                                            hc->infix,
                                            gorc->session_id,
                                            hc->instance->settings.id,
                                            ct);
    order_status_url = TMH_make_order_status_url (connection,
                                                  hc->infix,
                                                  gorc->session_id,
                                                  hc->instance->settings.id,
                                                  ct,
                                                  NULL);
    ret = TALER_MHD_reply_json_pack (connection,
                                     MHD_HTTP_OK,
                                     "{s:s, s:s, s:s}",
                                     "taler_pay_uri",
                                     taler_pay_uri,
                                     "order_status_url",
                                     order_status_url,
                                     "order_status",
                                     "unpaid");
    GNUNET_free (taler_pay_uri);
    GNUNET_free (order_status_url);
    return ret;
  }

  /* Here we know the user DID pay, compute refunds... */
  GNUNET_assert (! order_only);
  GNUNET_assert (paid);
  /* Accumulate refunds, if any. */
  {
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_get_zero (TMH_currency,
                                          &gorc->refund_amount));
    qs = TMH_db->lookup_refunds_detailed (TMH_db->cls,
                                          hc->instance->settings.id,
                                          &gorc->h_contract_terms,
                                          &process_refunds_cb,
                                          gorc);
  }
  if (0 > qs)
  {
    GNUNET_break (0);
    return TALER_MHD_reply_with_error (connection,
                                       MHD_HTTP_INTERNAL_SERVER_ERROR,
                                       TALER_EC_GET_ORDERS_DB_FETCH_TRANSACTION_ERROR,
                                       NULL);
  }

  /* Generate final reply, including wire details if we have them */
  {
    MHD_RESULT ret;
    char *order_status_url;

    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_get_zero (TMH_currency,
                                          &gorc->deposits_total));
    GNUNET_assert (GNUNET_OK ==
                   TALER_amount_get_zero (TMH_currency,
                                          &gorc->deposit_fees_total));
    qs = TMH_db->lookup_transfer_details_by_order (TMH_db->cls,
                                                   gorc->order_serial,
                                                   &process_transfer_details,
                                                   gorc);
    if (0 > qs)
    {
      GNUNET_break (0);
      return TALER_MHD_reply_with_error (connection,
                                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                                         TALER_EC_PAY_DB_FETCH_TRANSACTION_ERROR,
                                         NULL);
    }

    if (! wired)
    {
      /* we believe(d) the wire transfer did not happen yet, check if maybe
         in light of new evidence it did */
      struct TALER_Amount expect_total;

      if (0 >
          TALER_amount_subtract (&expect_total,
                                 &gorc->contract_amount,
                                 &gorc->refund_amount))
      {
        GNUNET_break (0);
        return TALER_MHD_reply_with_error (connection,
                                           MHD_HTTP_INTERNAL_SERVER_ERROR,
                                           TALER_EC_GET_ORDERS_CONTRACT_CONTENT_INVALID,
                                           "refund exceeds contract value");
      }
      if (0 >
          TALER_amount_subtract (&expect_total,
                                 &expect_total,
                                 &gorc->deposit_fees_total))
      {
        GNUNET_break (0);
        return TALER_MHD_reply_with_error (connection,
                                           MHD_HTTP_INTERNAL_SERVER_ERROR,
                                           TALER_EC_GET_ORDERS_CONTRACT_CONTENT_INVALID,
                                           "deposit fees exceed total minus refunds");
      }
      if (0 >=
          TALER_amount_cmp (&expect_total,
                            &gorc->deposits_total))
      {
        struct GNUNET_TIME_Absolute timestamp;

        /* expect_total <= gorc->deposits_total: good: we got paid */
        wired = true;
        qs = TMH_db->mark_order_wired (TMH_db->cls,
                                       gorc->order_serial);
        GNUNET_break (qs >= 0); /* just warn if transaction failed */
        {
          struct GNUNET_JSON_Specification spec[] = {
            TALER_JSON_spec_absolute_time ("timestamp",
                                           &timestamp),
            GNUNET_JSON_spec_end ()
          };
          enum GNUNET_GenericReturnValue res;

          res = TALER_MHD_parse_internal_json_data (connection,
                                                    gorc->contract_terms,
                                                    spec);
          if (GNUNET_YES != res)
          {
            GNUNET_break (0);
            return res;
          }
        }
        TMH_notify_order_change (hc->instance,
                                 hc->infix,
                                 true, /* paid */
                                 false, /* technically unknown, but OK here */
                                 true, /* wired */
                                 timestamp,
                                 gorc->order_serial);
      }
    }

    {
      struct GNUNET_HashCode *h_contract = NULL;

      /* In a session-bound payment, allow the browser to check the order
       * status page (e.g. to get a refund).
       *
       * Note that we don't allow this outside of session-based payment, as
       * otherwise this becomes an oracle to convert order_id to h_contract.
       */if (NULL != gorc->session_id)
        h_contract = &gorc->h_contract_terms;

      order_status_url =
        TMH_make_order_status_url (connection,
                                   hc->infix,
                                   gorc->session_id,
                                   hc->instance->settings.id,
                                   &claim_token,
                                   h_contract);
    }

    ret = TALER_MHD_reply_json_pack (connection,
                                     MHD_HTTP_OK,
                                     "{s:o, s:I, s:I, s:o, s:O,"
                                     " s:s, s:b, s:b, s:o, s:o, s:o, s:s}",
                                     "wire_reports",
                                     gorc->wire_reports,
                                     "exchange_ec",
                                     (json_int_t) gorc->exchange_ec,
                                     "exchange_hc",
                                     (json_int_t) gorc->exchange_hc,
                                     "deposit_total",
                                     TALER_JSON_from_amount (
                                       &gorc->deposits_total),
                                     "contract_terms",
                                     gorc->contract_terms,
                                     "order_status",
                                     "paid",
                                     "refunded",
                                     gorc->refunded,
                                     "wired",
                                     wired,
                                     "refund_amount",
                                     TALER_JSON_from_amount (
                                       &gorc->refund_amount),
                                     "wire_details",
                                     gorc->wire_details,
                                     "refund_details",
                                     gorc->refund_details,
                                     "order_status_url",
                                     order_status_url);
    GNUNET_free (order_status_url);
    gorc->wire_details = NULL;
    gorc->wire_reports = NULL;
    gorc->refund_details = NULL;
    return ret;
  }
}