summaryrefslogtreecommitdiff
path: root/src/set/set_api.c
blob: a082c23c1ee0abb907fe4ec513920d768eac9119 (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
/*
     This file is part of GNUnet.
     Copyright (C) 2012-2016 GNUnet e.V.

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

     GNUnet 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
     Affero General Public License for more details.

     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
 */
/**
 * @file set/set_api.c
 * @brief api for the set service
 * @author Florian Dold
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_protocols.h"
#include "gnunet_set_service.h"
#include "set.h"


#define LOG(kind, ...) GNUNET_log_from (kind, "set-api", __VA_ARGS__)

struct SetCopyRequest
{
  struct SetCopyRequest *next;

  struct SetCopyRequest *prev;

  void *cls;

  GNUNET_SET_CopyReadyCallback cb;
};

/**
 * Opaque handle to a set.
 */
struct GNUNET_SET_Handle
{
  /**
   * Message queue for @e client.
   */
  struct GNUNET_MQ_Handle *mq;

  /**
   * Linked list of operations on the set.
   */
  struct GNUNET_SET_OperationHandle *ops_head;

  /**
   * Linked list of operations on the set.
   */
  struct GNUNET_SET_OperationHandle *ops_tail;

  /**
   * Callback for the current iteration over the set,
   * NULL if no iterator is active.
   */
  GNUNET_SET_ElementIterator iterator;

  /**
   * Closure for @e iterator
   */
  void *iterator_cls;

  /**
   * Should the set be destroyed once all operations are gone?
   * #GNUNET_SYSERR if #GNUNET_SET_destroy() must raise this flag,
   * #GNUNET_YES if #GNUNET_SET_destroy() did raise this flag.
   */
  int destroy_requested;

  /**
   * Has the set become invalid (e.g. service died)?
   */
  int invalid;

  /**
   * Both client and service count the number of iterators
   * created so far to match replies with iterators.
   */
  uint16_t iteration_id;

  /**
   * Configuration, needed when creating (lazy) copies.
   */
  const struct GNUNET_CONFIGURATION_Handle *cfg;

  /**
   * Doubly linked list of copy requests.
   */
  struct SetCopyRequest *copy_req_head;

  /**
   * Doubly linked list of copy requests.
   */
  struct SetCopyRequest *copy_req_tail;
};


/**
 * Handle for a set operation request from another peer.
 */
struct GNUNET_SET_Request
{
  /**
   * Id of the request, used to identify the request when
   * accepting/rejecting it.
   */
  uint32_t accept_id;

  /**
   * Has the request been accepted already?
   * #GNUNET_YES/#GNUNET_NO
   */
  int accepted;
};


/**
 * Handle to an operation.  Only known to the service after committing
 * the handle with a set.
 */
struct GNUNET_SET_OperationHandle
{
  /**
   * Function to be called when we have a result,
   * or an error.
   */
  GNUNET_SET_ResultIterator result_cb;

  /**
   * Closure for @e result_cb.
   */
  void *result_cls;

  /**
   * Local set used for the operation,
   * NULL if no set has been provided by conclude yet.
   */
  struct GNUNET_SET_Handle *set;

  /**
   * Message sent to the server on calling conclude,
   * NULL if conclude has been called.
   */
  struct GNUNET_MQ_Envelope *conclude_mqm;

  /**
   * Address of the request if in the conclude message,
   * used to patch the request id into the message when the set is known.
   */
  uint32_t *request_id_addr;

  /**
   * Handles are kept in a linked list.
   */
  struct GNUNET_SET_OperationHandle *prev;

  /**
   * Handles are kept in a linked list.
   */
  struct GNUNET_SET_OperationHandle *next;

  /**
   * Request ID to identify the operation within the set.
   */
  uint32_t request_id;
};


/**
 * Opaque handle to a listen operation.
 */
struct GNUNET_SET_ListenHandle
{
  /**
   * Message queue for the client.
   */
  struct GNUNET_MQ_Handle*mq;

  /**
   * Configuration handle for the listener, stored
   * here to be able to reconnect transparently on
   * connection failure.
   */
  const struct GNUNET_CONFIGURATION_Handle *cfg;

  /**
   * Function to call on a new incoming request,
   * or on error.
   */
  GNUNET_SET_ListenCallback listen_cb;

  /**
   * Closure for @e listen_cb.
   */
  void *listen_cls;

  /**
   * Application ID we listen for.
   */
  struct GNUNET_HashCode app_id;

  /**
   * Time to wait until we try to reconnect on failure.
   */
  struct GNUNET_TIME_Relative reconnect_backoff;

  /**
   * Task for reconnecting when the listener fails.
   */
  struct GNUNET_SCHEDULER_Task *reconnect_task;

  /**
   * Operation we listen for.
   */
  enum GNUNET_SET_OperationType operation;
};


/* mutual recursion with handle_copy_lazy */
static struct GNUNET_SET_Handle *
create_internal (const struct GNUNET_CONFIGURATION_Handle *cfg,
                 enum GNUNET_SET_OperationType op,
                 const uint32_t *cookie);


/**
 * Handle element for iteration over the set.  Notifies the
 * iterator and sends an acknowledgement to the service.
 *
 * @param cls the `struct GNUNET_SET_Handle *`
 * @param msg the message
 */
static void
handle_copy_lazy (void *cls,
                  const struct GNUNET_SET_CopyLazyResponseMessage *msg)
{
  struct GNUNET_SET_Handle *set = cls;
  struct SetCopyRequest *req;
  struct GNUNET_SET_Handle *new_set;

  req = set->copy_req_head;
  if (NULL == req)
  {
    /* Service sent us unsolicited lazy copy response */
    GNUNET_break (0);
    return;
  }

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Handling response to lazy copy\n");
  GNUNET_CONTAINER_DLL_remove (set->copy_req_head,
                               set->copy_req_tail,
                               req);
  // We pass none as operation here, since it doesn't matter when
  // cloning.
  new_set = create_internal (set->cfg,
                             GNUNET_SET_OPERATION_NONE,
                             &msg->cookie);
  req->cb (req->cls, new_set);
  GNUNET_free (req);
}


/**
 * Check that the given @a msg is well-formed.
 *
 * @param cls closure
 * @param msg message to check
 * @return #GNUNET_OK if message is well-formed
 */
static int
check_iter_element (void *cls,
                    const struct GNUNET_SET_IterResponseMessage *msg)
{
  /* minimum size was already checked, everything else is OK! */
  return GNUNET_OK;
}


/**
 * Handle element for iteration over the set.  Notifies the
 * iterator and sends an acknowledgement to the service.
 *
 * @param cls the `struct GNUNET_SET_Handle *`
 * @param mh the message
 */
static void
handle_iter_element (void *cls,
                     const struct GNUNET_SET_IterResponseMessage *msg)
{
  struct GNUNET_SET_Handle *set = cls;
  GNUNET_SET_ElementIterator iter = set->iterator;
  struct GNUNET_SET_Element element;
  struct GNUNET_SET_IterAckMessage *ack_msg;
  struct GNUNET_MQ_Envelope *ev;
  uint16_t msize;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Received element in set iteration\n");
  msize = ntohs (msg->header.size);
  if (set->iteration_id != ntohs (msg->iteration_id))
  {
    /* element from a previous iteration, skip! */
    iter = NULL;
  }
  if (NULL != iter)
  {
    element.size = msize - sizeof(struct GNUNET_SET_IterResponseMessage);
    element.element_type = ntohs (msg->element_type);
    element.data = &msg[1];
    iter (set->iterator_cls,
          &element);
  }
  ev = GNUNET_MQ_msg (ack_msg,
                      GNUNET_MESSAGE_TYPE_SET_ITER_ACK);
  ack_msg->send_more = htonl ((NULL != iter));
  GNUNET_MQ_send (set->mq, ev);
}


/**
 * Handle message signalling conclusion of iteration over the set.
 * Notifies the iterator that we are done.
 *
 * @param cls the set
 * @param mh the message
 */
static void
handle_iter_done (void *cls,
                  const struct GNUNET_MessageHeader *mh)
{
  struct GNUNET_SET_Handle *set = cls;
  GNUNET_SET_ElementIterator iter = set->iterator;

  if (NULL == iter)
  {
    /* FIXME: if this is true, could cancel+start a fresh one
       cause elements to go to the wrong iteration? */
    LOG (GNUNET_ERROR_TYPE_INFO,
         "Service completed set iteration that was already cancelled\n");
    return;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Set iteration completed\n");
  set->destroy_requested = GNUNET_SYSERR;
  set->iterator = NULL;
  set->iteration_id++;
  iter (set->iterator_cls,
        NULL);
  if (GNUNET_SYSERR == set->destroy_requested)
    set->destroy_requested = GNUNET_NO;
  if (GNUNET_YES == set->destroy_requested)
    GNUNET_SET_destroy (set);
}


/**
 * Check that the given @a msg is well-formed.
 *
 * @param cls closure
 * @param msg message to check
 * @return #GNUNET_OK if message is well-formed
 */
static int
check_result (void *cls,
              const struct GNUNET_SET_ResultMessage *msg)
{
  /* minimum size was already checked, everything else is OK! */
  return GNUNET_OK;
}


/**
 * Handle result message for a set operation.
 *
 * @param cls the set
 * @param mh the message
 */
static void
handle_result (void *cls,
               const struct GNUNET_SET_ResultMessage *msg)
{
  struct GNUNET_SET_Handle *set = cls;
  struct GNUNET_SET_OperationHandle *oh;
  struct GNUNET_SET_Element e;
  enum GNUNET_SET_Status result_status;
  int destroy_set;

  GNUNET_assert (NULL != set->mq);
  result_status = (enum GNUNET_SET_Status) ntohs (msg->result_status);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Got result message with status %d\n",
       result_status);

  oh = GNUNET_MQ_assoc_get (set->mq,
                            ntohl (msg->request_id));
  if (NULL == oh)
  {
    /* 'oh' can be NULL if we canceled the operation, but the service
       did not get the cancel message yet. */
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Ignoring result from canceled operation\n");
    return;
  }

  switch (result_status)
  {
  case GNUNET_SET_STATUS_OK:
  case GNUNET_SET_STATUS_ADD_LOCAL:
  case GNUNET_SET_STATUS_ADD_REMOTE:
    goto do_element;

  case GNUNET_SET_STATUS_FAILURE:
  case GNUNET_SET_STATUS_DONE:
    goto do_final;

  case GNUNET_SET_STATUS_HALF_DONE:
    /* not used anymore */
    GNUNET_assert (0);
  }

do_final:
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Treating result as final status\n");
  GNUNET_MQ_assoc_remove (set->mq,
                          ntohl (msg->request_id));
  GNUNET_CONTAINER_DLL_remove (set->ops_head,
                               set->ops_tail,
                               oh);
  /* Need to do this calculation _before_ the result callback,
     as IF the application still has a valid set handle, it
     may trigger destruction of the set during the callback. */
  destroy_set = (GNUNET_YES == set->destroy_requested) &&
                (NULL == set->ops_head);
  if (NULL != oh->result_cb)
  {
    oh->result_cb (oh->result_cls,
                   NULL,
                   GNUNET_ntohll (msg->current_size),
                   result_status);
  }
  else
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "No callback for final status\n");
  }
  if (destroy_set)
    GNUNET_SET_destroy (set);
  GNUNET_free (oh);
  return;

do_element:
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Treating result as element\n");
  e.data = &msg[1];
  e.size = ntohs (msg->header.size) - sizeof(struct GNUNET_SET_ResultMessage);
  e.element_type = ntohs (msg->element_type);
  if (NULL != oh->result_cb)
    oh->result_cb (oh->result_cls,
                   &e,
                   GNUNET_ntohll (msg->current_size),
                   result_status);
}


/**
 * Destroy the given set operation.
 *
 * @param oh set operation to destroy
 */
static void
set_operation_destroy (struct GNUNET_SET_OperationHandle *oh)
{
  struct GNUNET_SET_Handle *set = oh->set;
  struct GNUNET_SET_OperationHandle *h_assoc;

  if (NULL != oh->conclude_mqm)
    GNUNET_MQ_discard (oh->conclude_mqm);
  /* is the operation already commited? */
  if (NULL != set)
  {
    GNUNET_CONTAINER_DLL_remove (set->ops_head,
                                 set->ops_tail,
                                 oh);
    h_assoc = GNUNET_MQ_assoc_remove (set->mq,
                                      oh->request_id);
    GNUNET_assert ((NULL == h_assoc) ||
                   (h_assoc == oh));
  }
  GNUNET_free (oh);
}


/**
 * Cancel the given set operation.  We need to send an explicit cancel
 * message, as all operations one one set communicate using one
 * handle.
 *
 * @param oh set operation to cancel
 */
void
GNUNET_SET_operation_cancel (struct GNUNET_SET_OperationHandle *oh)
{
  struct GNUNET_SET_Handle *set = oh->set;
  struct GNUNET_SET_CancelMessage *m;
  struct GNUNET_MQ_Envelope *mqm;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Cancelling SET operation\n");
  if (NULL != set)
  {
    mqm = GNUNET_MQ_msg (m, GNUNET_MESSAGE_TYPE_SET_CANCEL);
    m->request_id = htonl (oh->request_id);
    GNUNET_MQ_send (set->mq, mqm);
  }
  set_operation_destroy (oh);
  if ((NULL != set) &&
      (GNUNET_YES == set->destroy_requested) &&
      (NULL == set->ops_head))
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Destroying set after operation cancel\n");
    GNUNET_SET_destroy (set);
  }
}


/**
 * We encountered an error communicating with the set service while
 * performing a set operation. Report to the application.
 *
 * @param cls the `struct GNUNET_SET_Handle`
 * @param error error code
 */
static void
handle_client_set_error (void *cls,
                         enum GNUNET_MQ_Error error)
{
  struct GNUNET_SET_Handle *set = cls;
  GNUNET_SET_ElementIterator iter = set->iterator;

  LOG (GNUNET_ERROR_TYPE_ERROR,
       "Handling client set error %d\n",
       error);
  while (NULL != set->ops_head)
  {
    if ((NULL != set->ops_head->result_cb) &&
        (GNUNET_NO == set->destroy_requested))
      set->ops_head->result_cb (set->ops_head->result_cls,
                                NULL,
                                0,
                                GNUNET_SET_STATUS_FAILURE);
    set_operation_destroy (set->ops_head);
  }
  set->iterator = NULL;
  set->iteration_id++;
  set->invalid = GNUNET_YES;
  if (NULL != iter)
    iter (set->iterator_cls,
          NULL);
}


/**
 * FIXME.
 */
static struct GNUNET_SET_Handle *
create_internal (const struct GNUNET_CONFIGURATION_Handle *cfg,
                 enum GNUNET_SET_OperationType op,
                 const uint32_t *cookie)
{
  struct GNUNET_SET_Handle *set = GNUNET_new (struct GNUNET_SET_Handle);
  struct GNUNET_MQ_MessageHandler mq_handlers[] = {
    GNUNET_MQ_hd_var_size (result,
                           GNUNET_MESSAGE_TYPE_SET_RESULT,
                           struct GNUNET_SET_ResultMessage,
                           set),
    GNUNET_MQ_hd_var_size (iter_element,
                           GNUNET_MESSAGE_TYPE_SET_ITER_ELEMENT,
                           struct GNUNET_SET_IterResponseMessage,
                           set),
    GNUNET_MQ_hd_fixed_size (iter_done,
                             GNUNET_MESSAGE_TYPE_SET_ITER_DONE,
                             struct GNUNET_MessageHeader,
                             set),
    GNUNET_MQ_hd_fixed_size (copy_lazy,
                             GNUNET_MESSAGE_TYPE_SET_COPY_LAZY_RESPONSE,
                             struct GNUNET_SET_CopyLazyResponseMessage,
                             set),
    GNUNET_MQ_handler_end ()
  };
  struct GNUNET_MQ_Envelope *mqm;
  struct GNUNET_SET_CreateMessage *create_msg;
  struct GNUNET_SET_CopyLazyConnectMessage *copy_msg;

  set->cfg = cfg;
  set->mq = GNUNET_CLIENT_connect (cfg,
                                   "set",
                                   mq_handlers,
                                   &handle_client_set_error,
                                   set);
  if (NULL == set->mq)
  {
    GNUNET_free (set);
    return NULL;
  }
  if (NULL == cookie)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Creating new set (operation %u)\n",
         op);
    mqm = GNUNET_MQ_msg (create_msg,
                         GNUNET_MESSAGE_TYPE_SET_CREATE);
    create_msg->operation = htonl (op);
  }
  else
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Creating new set (lazy copy)\n");
    mqm = GNUNET_MQ_msg (copy_msg,
                         GNUNET_MESSAGE_TYPE_SET_COPY_LAZY_CONNECT);
    copy_msg->cookie = *cookie;
  }
  GNUNET_MQ_send (set->mq,
                  mqm);
  return set;
}


/**
 * Create an empty set, supporting the specified operation.
 *
 * @param cfg configuration to use for connecting to the
 *        set service
 * @param op operation supported by the set
 *        Note that the operation has to be specified
 *        beforehand, as certain set operations need to maintain
 *        data structures spefific to the operation
 * @return a handle to the set
 */
struct GNUNET_SET_Handle *
GNUNET_SET_create (const struct GNUNET_CONFIGURATION_Handle *cfg,
                   enum GNUNET_SET_OperationType op)
{
  struct GNUNET_SET_Handle *set;

  set = create_internal (cfg,
                         op,
                         NULL);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Creating set %p for operation %d\n",
       set,
       op);
  return set;
}


/**
 * Add an element to the given set.  After the element has been added
 * (in the sense of being transmitted to the set service), @a cont
 * will be called.  Multiple calls to GNUNET_SET_add_element() can be
 * queued.
 *
 * @param set set to add element to
 * @param element element to add to the set
 * @param cont continuation called after the element has been added
 * @param cont_cls closure for @a cont
 * @return #GNUNET_OK on success, #GNUNET_SYSERR if the
 *         set is invalid (e.g. the set service crashed)
 */
int
GNUNET_SET_add_element (struct GNUNET_SET_Handle *set,
                        const struct GNUNET_SET_Element *element,
                        GNUNET_SET_Continuation cont,
                        void *cont_cls)
{
  struct GNUNET_MQ_Envelope *mqm;
  struct GNUNET_SET_ElementMessage *msg;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "adding element of type %u to set %p\n",
       (unsigned int) element->element_type,
       set);
  GNUNET_assert (NULL != set);
  if (GNUNET_YES == set->invalid)
  {
    if (NULL != cont)
      cont (cont_cls);
    return GNUNET_SYSERR;
  }
  mqm = GNUNET_MQ_msg_extra (msg,
                             element->size,
                             GNUNET_MESSAGE_TYPE_SET_ADD);
  msg->element_type = htons (element->element_type);
  GNUNET_memcpy (&msg[1],
                 element->data,
                 element->size);
  GNUNET_MQ_notify_sent (mqm,
                         cont, cont_cls);
  GNUNET_MQ_send (set->mq, mqm);
  return GNUNET_OK;
}


/**
 * Remove an element to the given set.  After the element has been
 * removed (in the sense of the request being transmitted to the set
 * service), @a cont will be called.  Multiple calls to
 * GNUNET_SET_remove_element() can be queued
 *
 * @param set set to remove element from
 * @param element element to remove from the set
 * @param cont continuation called after the element has been removed
 * @param cont_cls closure for @a cont
 * @return #GNUNET_OK on success, #GNUNET_SYSERR if the
 *         set is invalid (e.g. the set service crashed)
 */
int
GNUNET_SET_remove_element (struct GNUNET_SET_Handle *set,
                           const struct GNUNET_SET_Element *element,
                           GNUNET_SET_Continuation cont,
                           void *cont_cls)
{
  struct GNUNET_MQ_Envelope *mqm;
  struct GNUNET_SET_ElementMessage *msg;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Removing element from set %p\n",
       set);
  if (GNUNET_YES == set->invalid)
  {
    if (NULL != cont)
      cont (cont_cls);
    return GNUNET_SYSERR;
  }
  mqm = GNUNET_MQ_msg_extra (msg,
                             element->size,
                             GNUNET_MESSAGE_TYPE_SET_REMOVE);
  msg->element_type = htons (element->element_type);
  GNUNET_memcpy (&msg[1],
                 element->data,
                 element->size);
  GNUNET_MQ_notify_sent (mqm,
                         cont, cont_cls);
  GNUNET_MQ_send (set->mq, mqm);
  return GNUNET_OK;
}


/**
 * Destroy the set handle if no operations are left, mark the set
 * for destruction otherwise.
 *
 * @param set set handle to destroy
 */
void
GNUNET_SET_destroy (struct GNUNET_SET_Handle *set)
{
  /* destroying set while iterator is active is currently
     not supported; we should expand the API to allow
     clients to explicitly cancel the iteration! */
  GNUNET_assert (NULL != set);
  if ((NULL != set->ops_head) ||
      (NULL != set->iterator) ||
      (GNUNET_SYSERR == set->destroy_requested))
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Set operations are pending, delaying set destruction\n");
    set->destroy_requested = GNUNET_YES;
    return;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Really destroying set\n");
  if (NULL != set->mq)
  {
    GNUNET_MQ_destroy (set->mq);
    set->mq = NULL;
  }
  GNUNET_free (set);
}


/**
 * Prepare a set operation to be evaluated with another peer.
 * The evaluation will not start until the client provides
 * a local set with #GNUNET_SET_commit().
 *
 * @param other_peer peer with the other set
 * @param app_id hash for the application using the set
 * @param context_msg additional information for the request
 * @param result_mode specified how results will be returned,
 *        see `enum GNUNET_SET_ResultMode`.
 * @param result_cb called on error or success
 * @param result_cls closure for @e result_cb
 * @return a handle to cancel the operation
 */
struct GNUNET_SET_OperationHandle *
GNUNET_SET_prepare (const struct GNUNET_PeerIdentity *other_peer,
                    const struct GNUNET_HashCode *app_id,
                    const struct GNUNET_MessageHeader *context_msg,
                    enum GNUNET_SET_ResultMode result_mode,
                    struct GNUNET_SET_Option options[],
                    GNUNET_SET_ResultIterator result_cb,
                    void *result_cls)
{
  struct GNUNET_MQ_Envelope *mqm;
  struct GNUNET_SET_OperationHandle *oh;
  struct GNUNET_SET_EvaluateMessage *msg;
  struct GNUNET_SET_Option *opt;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Client prepares set operation (%d)\n",
       result_mode);
  oh = GNUNET_new (struct GNUNET_SET_OperationHandle);
  oh->result_cb = result_cb;
  oh->result_cls = result_cls;
  mqm = GNUNET_MQ_msg_nested_mh (msg,
                                 GNUNET_MESSAGE_TYPE_SET_EVALUATE,
                                 context_msg);
  msg->app_id = *app_id;
  msg->result_mode = htonl (result_mode);
  msg->target_peer = *other_peer;
  for (opt = options; opt->type != 0; opt++)
  {
    switch (opt->type)
    {
    case GNUNET_SET_OPTION_BYZANTINE:
      msg->byzantine = GNUNET_YES;
      msg->byzantine_lower_bound = opt->v.num;
      break;

    case GNUNET_SET_OPTION_FORCE_FULL:
      msg->force_full = GNUNET_YES;
      break;

    case GNUNET_SET_OPTION_FORCE_DELTA:
      msg->force_delta = GNUNET_YES;
      break;

    default:
      LOG (GNUNET_ERROR_TYPE_ERROR,
           "Option with type %d not recognized\n", (int) opt->type);
    }
  }
  oh->conclude_mqm = mqm;
  oh->request_id_addr = &msg->request_id;

  return oh;
}


/**
 * Connect to the set service in order to listen for requests.
 *
 * @param cls the `struct GNUNET_SET_ListenHandle *` to connect
 */
static void
listen_connect (void *cls);


/**
 * Check validity of request message for a listen operation
 *
 * @param cls the listen handle
 * @param msg the message
 * @return #GNUNET_OK if the message is well-formed
 */
static int
check_request (void *cls,
               const struct GNUNET_SET_RequestMessage *msg)
{
  const struct GNUNET_MessageHeader *context_msg;

  if (ntohs (msg->header.size) == sizeof(*msg))
    return GNUNET_OK; /* no context message is OK */
  context_msg = GNUNET_MQ_extract_nested_mh (msg);
  if (NULL == context_msg)
  {
    /* malformed context message is NOT ok */
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Handle request message for a listen operation
 *
 * @param cls the listen handle
 * @param msg the message
 */
static void
handle_request (void *cls,
                const struct GNUNET_SET_RequestMessage *msg)
{
  struct GNUNET_SET_ListenHandle *lh = cls;
  struct GNUNET_SET_Request req;
  const struct GNUNET_MessageHeader *context_msg;
  struct GNUNET_MQ_Envelope *mqm;
  struct GNUNET_SET_RejectMessage *rmsg;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Processing incoming operation request with id %u\n",
       ntohl (msg->accept_id));
  /* we got another valid request => reset the backoff */
  lh->reconnect_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
  req.accept_id = ntohl (msg->accept_id);
  req.accepted = GNUNET_NO;
  context_msg = GNUNET_MQ_extract_nested_mh (msg);
  /* calling #GNUNET_SET_accept() in the listen cb will set req->accepted */
  lh->listen_cb (lh->listen_cls,
                 &msg->peer_id,
                 context_msg,
                 &req);
  if (GNUNET_YES == req.accepted)
    return; /* the accept-case is handled in #GNUNET_SET_accept() */
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Rejected request %u\n",
       ntohl (msg->accept_id));
  mqm = GNUNET_MQ_msg (rmsg,
                       GNUNET_MESSAGE_TYPE_SET_REJECT);
  rmsg->accept_reject_id = msg->accept_id;
  GNUNET_MQ_send (lh->mq, mqm);
}


/**
 * Our connection with the set service encountered an error,
 * re-initialize with exponential back-off.
 *
 * @param cls the `struct GNUNET_SET_ListenHandle *`
 * @param error reason for the disconnect
 */
static void
handle_client_listener_error (void *cls,
                              enum GNUNET_MQ_Error error)
{
  struct GNUNET_SET_ListenHandle *lh = cls;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Listener broke down (%d), re-connecting\n",
       (int) error);
  GNUNET_MQ_destroy (lh->mq);
  lh->mq = NULL;
  lh->reconnect_task = GNUNET_SCHEDULER_add_delayed (lh->reconnect_backoff,
                                                     &listen_connect,
                                                     lh);
  lh->reconnect_backoff = GNUNET_TIME_STD_BACKOFF (lh->reconnect_backoff);
}


/**
 * Connect to the set service in order to listen for requests.
 *
 * @param cls the `struct GNUNET_SET_ListenHandle *` to connect
 */
static void
listen_connect (void *cls)
{
  struct GNUNET_SET_ListenHandle *lh = cls;
  struct GNUNET_MQ_MessageHandler mq_handlers[] = {
    GNUNET_MQ_hd_var_size (request,
                           GNUNET_MESSAGE_TYPE_SET_REQUEST,
                           struct GNUNET_SET_RequestMessage,
                           lh),
    GNUNET_MQ_handler_end ()
  };
  struct GNUNET_MQ_Envelope *mqm;
  struct GNUNET_SET_ListenMessage *msg;

  lh->reconnect_task = NULL;
  GNUNET_assert (NULL == lh->mq);
  lh->mq = GNUNET_CLIENT_connect (lh->cfg,
                                  "set",
                                  mq_handlers,
                                  &handle_client_listener_error,
                                  lh);
  if (NULL == lh->mq)
    return;
  mqm = GNUNET_MQ_msg (msg, GNUNET_MESSAGE_TYPE_SET_LISTEN);
  msg->operation = htonl (lh->operation);
  msg->app_id = lh->app_id;
  GNUNET_MQ_send (lh->mq,
                  mqm);
}


/**
 * Wait for set operation requests for the given application id
 *
 * @param cfg configuration to use for connecting to
 *            the set service, needs to be valid for the lifetime of the listen handle
 * @param operation operation we want to listen for
 * @param app_id id of the application that handles set operation requests
 * @param listen_cb called for each incoming request matching the operation
 *                  and application id
 * @param listen_cls handle for @a listen_cb
 * @return a handle that can be used to cancel the listen operation
 */
struct GNUNET_SET_ListenHandle *
GNUNET_SET_listen (const struct GNUNET_CONFIGURATION_Handle *cfg,
                   enum GNUNET_SET_OperationType operation,
                   const struct GNUNET_HashCode *app_id,
                   GNUNET_SET_ListenCallback listen_cb,
                   void *listen_cls)
{
  struct GNUNET_SET_ListenHandle *lh;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Starting listener for app %s\n",
       GNUNET_h2s (app_id));
  lh = GNUNET_new (struct GNUNET_SET_ListenHandle);
  lh->listen_cb = listen_cb;
  lh->listen_cls = listen_cls;
  lh->cfg = cfg;
  lh->operation = operation;
  lh->app_id = *app_id;
  lh->reconnect_backoff = GNUNET_TIME_UNIT_MILLISECONDS;
  listen_connect (lh);
  if (NULL == lh->mq)
  {
    GNUNET_free (lh);
    return NULL;
  }
  return lh;
}


/**
 * Cancel the given listen operation.
 *
 * @param lh handle for the listen operation
 */
void
GNUNET_SET_listen_cancel (struct GNUNET_SET_ListenHandle *lh)
{
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Canceling listener %s\n",
       GNUNET_h2s (&lh->app_id));
  if (NULL != lh->mq)
  {
    GNUNET_MQ_destroy (lh->mq);
    lh->mq = NULL;
  }
  if (NULL != lh->reconnect_task)
  {
    GNUNET_SCHEDULER_cancel (lh->reconnect_task);
    lh->reconnect_task = NULL;
  }
  GNUNET_free (lh);
}


/**
 * Accept a request we got via #GNUNET_SET_listen.  Must be called during
 * #GNUNET_SET_listen, as the 'struct GNUNET_SET_Request' becomes invalid
 * afterwards.
 * Call #GNUNET_SET_commit to provide the local set to use for the operation,
 * and to begin the exchange with the remote peer.
 *
 * @param request request to accept
 * @param result_mode specified how results will be returned,
 *        see `enum GNUNET_SET_ResultMode`.
 * @param result_cb callback for the results
 * @param result_cls closure for @a result_cb
 * @return a handle to cancel the operation
 */
struct GNUNET_SET_OperationHandle *
GNUNET_SET_accept (struct GNUNET_SET_Request *request,
                   enum GNUNET_SET_ResultMode result_mode,
                   struct GNUNET_SET_Option options[],
                   GNUNET_SET_ResultIterator result_cb,
                   void *result_cls)
{
  struct GNUNET_MQ_Envelope *mqm;
  struct GNUNET_SET_OperationHandle *oh;
  struct GNUNET_SET_AcceptMessage *msg;

  GNUNET_assert (GNUNET_NO == request->accepted);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Client accepts set operation (%d) with id %u\n",
       result_mode,
       request->accept_id);
  request->accepted = GNUNET_YES;
  mqm = GNUNET_MQ_msg (msg,
                       GNUNET_MESSAGE_TYPE_SET_ACCEPT);
  msg->accept_reject_id = htonl (request->accept_id);
  msg->result_mode = htonl (result_mode);
  oh = GNUNET_new (struct GNUNET_SET_OperationHandle);
  oh->result_cb = result_cb;
  oh->result_cls = result_cls;
  oh->conclude_mqm = mqm;
  oh->request_id_addr = &msg->request_id;
  return oh;
}


/**
 * Commit a set to be used with a set operation.
 * This function is called once we have fully constructed
 * the set that we want to use for the operation.  At this
 * time, the P2P protocol can then begin to exchange the
 * set information and call the result callback with the
 * result information.
 *
 * @param oh handle to the set operation
 * @param set the set to use for the operation
 * @return #GNUNET_OK on success, #GNUNET_SYSERR if the
 *         set is invalid (e.g. the set service crashed)
 */
int
GNUNET_SET_commit (struct GNUNET_SET_OperationHandle *oh,
                   struct GNUNET_SET_Handle *set)
{
  if (NULL != oh->set)
  {
    /* Some other set was already committed for this
     * operation, there is a logic bug in the client of this API */
    GNUNET_break (0);
    return GNUNET_OK;
  }
  GNUNET_assert (NULL != set);
  if (GNUNET_YES == set->invalid)
    return GNUNET_SYSERR;
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Client commits to SET\n");
  GNUNET_assert (NULL != oh->conclude_mqm);
  oh->set = set;
  GNUNET_CONTAINER_DLL_insert (set->ops_head,
                               set->ops_tail,
                               oh);
  oh->request_id = GNUNET_MQ_assoc_add (set->mq,
                                        oh);
  *oh->request_id_addr = htonl (oh->request_id);
  GNUNET_MQ_send (set->mq,
                  oh->conclude_mqm);
  oh->conclude_mqm = NULL;
  oh->request_id_addr = NULL;
  return GNUNET_OK;
}


/**
 * Iterate over all elements in the given set.  Note that this
 * operation involves transferring every element of the set from the
 * service to the client, and is thus costly.
 *
 * @param set the set to iterate over
 * @param iter the iterator to call for each element
 * @param iter_cls closure for @a iter
 * @return #GNUNET_YES if the iteration started successfuly,
 *         #GNUNET_NO if another iteration is active
 *         #GNUNET_SYSERR if the set is invalid (e.g. the server crashed, disconnected)
 */
int
GNUNET_SET_iterate (struct GNUNET_SET_Handle *set,
                    GNUNET_SET_ElementIterator iter,
                    void *iter_cls)
{
  struct GNUNET_MQ_Envelope *ev;

  GNUNET_assert (NULL != iter);
  if (GNUNET_YES == set->invalid)
    return GNUNET_SYSERR;
  if (NULL != set->iterator)
    return GNUNET_NO;
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Iterating over set\n");
  set->iterator = iter;
  set->iterator_cls = iter_cls;
  ev = GNUNET_MQ_msg_header (GNUNET_MESSAGE_TYPE_SET_ITER_REQUEST);
  GNUNET_MQ_send (set->mq, ev);
  return GNUNET_YES;
}


void
GNUNET_SET_copy_lazy (struct GNUNET_SET_Handle *set,
                      GNUNET_SET_CopyReadyCallback cb,
                      void *cls)
{
  struct GNUNET_MQ_Envelope *ev;
  struct SetCopyRequest *req;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Creating lazy copy of set\n");
  ev = GNUNET_MQ_msg_header (GNUNET_MESSAGE_TYPE_SET_COPY_LAZY_PREPARE);
  GNUNET_MQ_send (set->mq, ev);

  req = GNUNET_new (struct SetCopyRequest);
  req->cb = cb;
  req->cls = cls;
  GNUNET_CONTAINER_DLL_insert (set->copy_req_head,
                               set->copy_req_tail,
                               req);
}


/**
 * Create a copy of an element.  The copy
 * must be GNUNET_free-d by the caller.
 *
 * @param element the element to copy
 * @return the copied element
 */
struct GNUNET_SET_Element *
GNUNET_SET_element_dup (const struct GNUNET_SET_Element *element)
{
  struct GNUNET_SET_Element *copy;

  copy = GNUNET_malloc (element->size + sizeof(struct GNUNET_SET_Element));
  copy->size = element->size;
  copy->element_type = element->element_type;
  copy->data = &copy[1];
  GNUNET_memcpy (&copy[1],
                 element->data,
                 copy->size);
  return copy;
}


/**
 * Hash a set element.
 *
 * @param element the element that should be hashed
 * @param[out] ret_hash a pointer to where the hash of @a element
 *        should be stored
 */
void
GNUNET_SET_element_hash (const struct GNUNET_SET_Element *element,
                         struct GNUNET_HashCode *ret_hash)
{
  struct GNUNET_HashContext *ctx = GNUNET_CRYPTO_hash_context_start ();

  /* It's not guaranteed that the element data is always after the element header,
     so we need to hash the chunks separately. */
  GNUNET_CRYPTO_hash_context_read (ctx, &element->size, sizeof(uint16_t));
  GNUNET_CRYPTO_hash_context_read (ctx, &element->element_type,
                                   sizeof(uint16_t));
  GNUNET_CRYPTO_hash_context_read (ctx, element->data, element->size);
  GNUNET_CRYPTO_hash_context_finish (ctx, ret_hash);
}


/* end of set_api.c */