summaryrefslogtreecommitdiff
path: root/src/revocation/gnunet-service-revocation.c
blob: 81a30748cb61c9c2f9df1ab8b9a32d540a8ca34f (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
/*
   This file is part of GNUnet.
   Copyright (C) 2013, 2014, 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 revocation/gnunet-service-revocation.c
 * @brief key revocation service
 * @author Christian Grothoff
 *
 * The purpose of this service is to allow users to permanently revoke
 * (compromised) keys.  This is done by flooding the network with the
 * revocation requests.  To reduce the attack potential offered by such
 * flooding, revocations must include a proof of work.  We use the
 * set service for efficiently computing the union of revocations of
 * peers that connect.
 *
 * TODO:
 * - optimization: avoid sending revocation back to peer that we got it from;
 * - optimization: have randomized delay in sending revocations to other peers
 *                 to make it rare to traverse each link twice (NSE-style)
 */
#include "platform.h"
#include <math.h>
#include "gnunet_util_lib.h"
#include "gnunet_block_lib.h"
#include "gnunet_constants.h"
#include "gnunet_protocols.h"
#include "gnunet_signatures.h"
#include "gnunet_statistics_service.h"
#include "gnunet_core_service.h"
#include "gnunet_revocation_service.h"
#include "gnunet_set_service.h"
#include "revocation.h"
#include <gcrypt.h>


/**
 * Per-peer information.
 */
struct PeerEntry
{
  /**
   * Queue for sending messages to this peer.
   */
  struct GNUNET_MQ_Handle *mq;

  /**
   * What is the identity of the peer?
   */
  struct GNUNET_PeerIdentity id;

  /**
   * Tasked used to trigger the set union operation.
   */
  struct GNUNET_SCHEDULER_Task *transmit_task;

  /**
   * Handle to active set union operation (over revocation sets).
   */
  struct GNUNET_SET_OperationHandle *so;
};


/**
 * Set from all revocations known to us.
 */
static struct GNUNET_SET_Handle *revocation_set;

/**
 * Hash map with all revoked keys, maps the hash of the public key
 * to the respective `struct RevokeMessage`.
 */
static struct GNUNET_CONTAINER_MultiHashMap *revocation_map;

/**
 * Handle to our current configuration.
 */
static const struct GNUNET_CONFIGURATION_Handle *cfg;

/**
 * Handle to the statistics service.
 */
static struct GNUNET_STATISTICS_Handle *stats;

/**
 * Handle to the core service (for flooding)
 */
static struct GNUNET_CORE_Handle *core_api;

/**
 * Map of all connected peers.
 */
static struct GNUNET_CONTAINER_MultiPeerMap *peers;

/**
 * The peer identity of this peer.
 */
static struct GNUNET_PeerIdentity my_identity;

/**
 * File handle for the revocation database.
 */
static struct GNUNET_DISK_FileHandle *revocation_db;

/**
 * Handle for us listening to incoming revocation set union requests.
 */
static struct GNUNET_SET_ListenHandle *revocation_union_listen_handle;

/**
 * Amount of work required (W-bit collisions) for REVOCATION proofs, in collision-bits.
 */
static unsigned long long revocation_work_required;

/**
 * Length of an expiration expoch
 */
static struct GNUNET_TIME_Relative epoch_duration;

/**
 * Our application ID for set union operations.  Must be the
 * same for all (compatible) peers.
 */
static struct GNUNET_HashCode revocation_set_union_app_id;


/**
 * Create a new PeerEntry and add it to the peers multipeermap.
 *
 * @param peer the peer identity
 * @return a pointer to the new PeerEntry
 */
static struct PeerEntry *
new_peer_entry (const struct GNUNET_PeerIdentity *peer)
{
  struct PeerEntry *peer_entry;

  peer_entry = GNUNET_new (struct PeerEntry);
  peer_entry->id = *peer;
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CONTAINER_multipeermap_put (peers,
                                                    &peer_entry->id,
                                                    peer_entry,
                                                    GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  return peer_entry;
}


/**
 * An revoke message has been received, check that it is well-formed.
 *
 * @param rm the message to verify
 * @return #GNUNET_YES if the message is verified
 *         #GNUNET_NO if the key/signature don't verify
 */
static int
verify_revoke_message (const struct RevokeMessage *rm)
{
  if (GNUNET_YES != GNUNET_REVOCATION_check_pow (&rm->proof_of_work,
                                                 (unsigned
                                                  int) revocation_work_required,
                                                 epoch_duration))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Proof of work invalid!\n");
    GNUNET_break_op (0);
    return GNUNET_NO;
  }
  return GNUNET_YES;
}


/**
 * Handle client connecting to the service.
 *
 * @param cls NULL
 * @param client the new client
 * @param mq the message queue of @a client
 * @return @a client
 */
static void *
client_connect_cb (void *cls,
                   struct GNUNET_SERVICE_Client *client,
                   struct GNUNET_MQ_Handle *mq)
{
  return client;
}


/**
 * Handle client connecting to the service.
 *
 * @param cls NULL
 * @param client the new client
 * @param app_cls must alias @a client
 */
static void
client_disconnect_cb (void *cls,
                      struct GNUNET_SERVICE_Client *client,
                      void *app_cls)
{
  GNUNET_assert (client == app_cls);
}


/**
 * Handle QUERY message from client.
 *
 * @param cls client who sent the message
 * @param qm the message received
 */
static void
handle_query_message (void *cls,
                      const struct QueryMessage *qm)
{
  struct GNUNET_SERVICE_Client *client = cls;
  struct GNUNET_MQ_Envelope *env;
  struct QueryResponseMessage *qrm;
  struct GNUNET_HashCode hc;
  int res;

  GNUNET_CRYPTO_hash (&qm->key,
                      sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
                      &hc);
  res = GNUNET_CONTAINER_multihashmap_contains (revocation_map,
                                                &hc);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              (GNUNET_NO == res)
              ? "Received revocation check for valid key `%s' from client\n"
              : "Received revocation check for revoked key `%s' from client\n",
              GNUNET_h2s (&hc));
  env = GNUNET_MQ_msg (qrm,
                       GNUNET_MESSAGE_TYPE_REVOCATION_QUERY_RESPONSE);
  qrm->is_valid = htonl ((GNUNET_YES == res) ? GNUNET_NO : GNUNET_YES);
  GNUNET_MQ_send (GNUNET_SERVICE_client_get_mq (client),
                  env);
  GNUNET_SERVICE_client_continue (client);
}


/**
 * Flood the given revocation message to all neighbours.
 *
 * @param cls the `struct RevokeMessage` to flood
 * @param target a neighbour
 * @param value our `struct PeerEntry` for the neighbour
 * @return #GNUNET_OK (continue to iterate)
 */
static int
do_flood (void *cls,
          const struct GNUNET_PeerIdentity *target,
          void *value)
{
  const struct RevokeMessage *rm = cls;
  struct PeerEntry *pe = value;
  struct GNUNET_MQ_Envelope *e;
  struct RevokeMessage *cp;

  if (NULL == pe->mq)
    return GNUNET_OK; /* peer connected to us via SET,
                         but we have no direct CORE
                         connection for flooding */
  e = GNUNET_MQ_msg (cp,
                     GNUNET_MESSAGE_TYPE_REVOCATION_REVOKE);
  *cp = *rm;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Flooding revocation to `%s'\n",
              GNUNET_i2s (target));
  GNUNET_MQ_send (pe->mq,
                  e);
  return GNUNET_OK;
}


/**
 * Publicize revocation message.   Stores the message locally in the
 * database and passes it to all connected neighbours (and adds it to
 * the set for future connections).
 *
 * @param rm message to publicize
 * @return #GNUNET_OK on success, #GNUNET_NO if we encountered an error,
 *         #GNUNET_SYSERR if the message was malformed
 */
static int
publicize_rm (const struct RevokeMessage *rm)
{
  struct RevokeMessage *cp;
  struct GNUNET_HashCode hc;
  struct GNUNET_SET_Element e;

  GNUNET_CRYPTO_hash (&rm->proof_of_work.key,
                      sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
                      &hc);
  if (GNUNET_YES ==
      GNUNET_CONTAINER_multihashmap_contains (revocation_map,
                                              &hc))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Duplicate revocation received from peer. Ignored.\n");
    return GNUNET_OK;
  }
  if (GNUNET_OK !=
      verify_revoke_message (rm))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  /* write to disk */
  if (sizeof(struct RevokeMessage) !=
      GNUNET_DISK_file_write (revocation_db,
                              rm,
                              sizeof(struct RevokeMessage)))
  {
    GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR,
                         "write");
    return GNUNET_NO;
  }
  if (GNUNET_OK !=
      GNUNET_DISK_file_sync (revocation_db))
  {
    GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR,
                         "sync");
    return GNUNET_NO;
  }
  /* keep copy in memory */
  cp = (struct RevokeMessage *) GNUNET_copy_message (&rm->header);
  GNUNET_break (GNUNET_OK ==
                GNUNET_CONTAINER_multihashmap_put (revocation_map,
                                                   &hc,
                                                   cp,
                                                   GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  /* add to set for future connections */
  e.size = htons (rm->header.size);
  e.element_type = GNUNET_BLOCK_TYPE_REVOCATION;
  e.data = rm;
  if (GNUNET_OK !=
      GNUNET_SET_add_element (revocation_set,
                              &e,
                              NULL,
                              NULL))
  {
    GNUNET_break (0);
    return GNUNET_OK;
  }
  else
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Added revocation info to SET\n");
  }
  /* flood to neighbours */
  GNUNET_CONTAINER_multipeermap_iterate (peers,
                                         &do_flood,
                                         cp);
  return GNUNET_OK;
}


/**
 * Handle REVOKE message from client.
 *
 * @param cls client who sent the message
 * @param rm the message received
 */
static void
handle_revoke_message (void *cls,
                       const struct RevokeMessage *rm)
{
  struct GNUNET_SERVICE_Client *client = cls;
  struct GNUNET_MQ_Envelope *env;
  struct RevocationResponseMessage *rrm;
  int ret;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received REVOKE message from client\n");
  if (GNUNET_SYSERR == (ret = publicize_rm (rm)))
  {
    GNUNET_break_op (0);
    GNUNET_SERVICE_client_drop (client);
    return;
  }
  env = GNUNET_MQ_msg (rrm,
                       GNUNET_MESSAGE_TYPE_REVOCATION_REVOKE_RESPONSE);
  rrm->is_valid = htonl ((GNUNET_OK == ret) ? GNUNET_NO : GNUNET_YES);
  GNUNET_MQ_send (GNUNET_SERVICE_client_get_mq (client),
                  env);
  GNUNET_SERVICE_client_continue (client);
}


/**
 * Core handler for flooded revocation messages.
 *
 * @param cls closure unused
 * @param rm revocation message
 */
static void
handle_p2p_revoke (void *cls,
                   const struct RevokeMessage *rm)
{
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received REVOKE message\n");
  GNUNET_break_op (GNUNET_SYSERR !=
                   publicize_rm (rm));
}


/**
 * Callback for set operation results. Called for each element in the
 * result set.  Each element contains a revocation, which we should
 * validate and then add to our revocation list (and set).
 *
 * @param cls closure
 * @param element a result element, only valid if status is #GNUNET_SET_STATUS_OK
 * @param current_size current set size
 * @param status see `enum GNUNET_SET_Status`
 */
static void
add_revocation (void *cls,
                const struct GNUNET_SET_Element *element,
                uint64_t current_size,
                enum GNUNET_SET_Status status)
{
  struct PeerEntry *peer_entry = cls;
  const struct RevokeMessage *rm;

  switch (status)
  {
  case GNUNET_SET_STATUS_OK:
    if (element->size != sizeof(struct RevokeMessage))
    {
      GNUNET_break_op (0);
      return;
    }
    if (GNUNET_BLOCK_TYPE_REVOCATION != element->element_type)
    {
      GNUNET_STATISTICS_update (stats,
                                gettext_noop (
                                  "# unsupported revocations received via set union"),
                                1,
                                GNUNET_NO);
      return;
    }
    rm = element->data;
    (void) handle_p2p_revoke (NULL,
                              rm);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop (
                                "# revocation messages received via set union"),
                              1, GNUNET_NO);
    break;

  case GNUNET_SET_STATUS_FAILURE:
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _ ("Error computing revocation set union with %s\n"),
                GNUNET_i2s (&peer_entry->id));
    peer_entry->so = NULL;
    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("# revocation set unions failed"),
                              1,
                              GNUNET_NO);
    break;

  case GNUNET_SET_STATUS_HALF_DONE:
    break;

  case GNUNET_SET_STATUS_DONE:
    peer_entry->so = NULL;
    GNUNET_STATISTICS_update (stats,
                              gettext_noop (
                                "# revocation set unions completed"),
                              1,
                              GNUNET_NO);
    break;

  default:
    GNUNET_break (0);
    break;
  }
}


/**
 * The timeout for performing the set union has expired,
 * run the set operation on the revocation certificates.
 *
 * @param cls NULL
 */
static void
transmit_task_cb (void *cls)
{
  struct PeerEntry *peer_entry = cls;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Starting set exchange with peer `%s'\n",
              GNUNET_i2s (&peer_entry->id));
  peer_entry->transmit_task = NULL;
  GNUNET_assert (NULL == peer_entry->so);
  peer_entry->so = GNUNET_SET_prepare (&peer_entry->id,
                                       &revocation_set_union_app_id,
                                       NULL,
                                       GNUNET_SET_RESULT_ADDED,
                                       (struct GNUNET_SET_Option[]) { { 0 } },
                                       &add_revocation,
                                       peer_entry);
  if (GNUNET_OK !=
      GNUNET_SET_commit (peer_entry->so,
                         revocation_set))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _ ("SET service crashed, terminating revocation service\n"));
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
}


/**
 * Method called whenever a peer connects. Sets up the PeerEntry and
 * schedules the initial revocation set exchange with this peer.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 */
static void *
handle_core_connect (void *cls,
                     const struct GNUNET_PeerIdentity *peer,
                     struct GNUNET_MQ_Handle *mq)
{
  struct PeerEntry *peer_entry;
  struct GNUNET_HashCode my_hash;
  struct GNUNET_HashCode peer_hash;

  if (0 == GNUNET_memcmp (peer,
                          &my_identity))
  {
    return NULL;
  }

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Peer `%s' connected to us\n",
              GNUNET_i2s (peer));
  GNUNET_STATISTICS_update (stats,
                            "# peers connected",
                            1,
                            GNUNET_NO);
  peer_entry = GNUNET_CONTAINER_multipeermap_get (peers,
                                                  peer);
  if (NULL != peer_entry)
  {
    /* This can happen if "core"'s notification is a tad late
       and CADET+SET were faster and already produced a
     #handle_revocation_union_request() for us to deal
       with.  This should be rare, but isn't impossible. */
    peer_entry->mq = mq;
    return peer_entry;
  }
  peer_entry = new_peer_entry (peer);
  peer_entry->mq = mq;
  GNUNET_CRYPTO_hash (&my_identity,
                      sizeof(my_identity),
                      &my_hash);
  GNUNET_CRYPTO_hash (peer,
                      sizeof(*peer),
                      &peer_hash);
  if (0 < GNUNET_CRYPTO_hash_cmp (&my_hash,
                                  &peer_hash))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Starting SET operation with peer `%s'\n",
                GNUNET_i2s (peer));
    peer_entry->transmit_task =
      GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_UNIT_SECONDS,
                                    &transmit_task_cb,
                                    peer_entry);
  }
  return peer_entry;
}


/**
 * Method called whenever a peer disconnects. Deletes the PeerEntry and cancels
 * any pending transmission requests to that peer.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 * @param internal_cls our `struct PeerEntry` for this peer
 */
static void
handle_core_disconnect (void *cls,
                        const struct GNUNET_PeerIdentity *peer,
                        void *internal_cls)
{
  struct PeerEntry *peer_entry = internal_cls;

  if (0 == GNUNET_memcmp (peer,
                          &my_identity))
    return;
  GNUNET_assert (NULL != peer_entry);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Peer `%s' disconnected from us\n",
              GNUNET_i2s (peer));
  GNUNET_assert (GNUNET_YES ==
                 GNUNET_CONTAINER_multipeermap_remove (peers,
                                                       peer,
                                                       peer_entry));
  if (NULL != peer_entry->transmit_task)
  {
    GNUNET_SCHEDULER_cancel (peer_entry->transmit_task);
    peer_entry->transmit_task = NULL;
  }
  if (NULL != peer_entry->so)
  {
    GNUNET_SET_operation_cancel (peer_entry->so);
    peer_entry->so = NULL;
  }
  GNUNET_free (peer_entry);
  GNUNET_STATISTICS_update (stats,
                            "# peers connected",
                            -1,
                            GNUNET_NO);
}


/**
 * Free all values in a hash map.
 *
 * @param cls NULL
 * @param key the key
 * @param value value to free
 * @return #GNUNET_OK (continue to iterate)
 */
static int
free_entry (void *cls,
            const struct GNUNET_HashCode *key,
            void *value)
{
  GNUNET_free (value);
  return GNUNET_OK;
}


/**
 * Task run during shutdown.
 *
 * @param cls unused
 */
static void
shutdown_task (void *cls)
{
  if (NULL != revocation_set)
  {
    GNUNET_SET_destroy (revocation_set);
    revocation_set = NULL;
  }
  if (NULL != revocation_union_listen_handle)
  {
    GNUNET_SET_listen_cancel (revocation_union_listen_handle);
    revocation_union_listen_handle = NULL;
  }
  if (NULL != core_api)
  {
    GNUNET_CORE_disconnect (core_api);
    core_api = NULL;
  }
  if (NULL != stats)
  {
    GNUNET_STATISTICS_destroy (stats, GNUNET_NO);
    stats = NULL;
  }
  if (NULL != peers)
  {
    GNUNET_CONTAINER_multipeermap_destroy (peers);
    peers = NULL;
  }
  if (NULL != revocation_db)
  {
    GNUNET_DISK_file_close (revocation_db);
    revocation_db = NULL;
  }
  GNUNET_CONTAINER_multihashmap_iterate (revocation_map,
                                         &free_entry,
                                         NULL);
  GNUNET_CONTAINER_multihashmap_destroy (revocation_map);
}


/**
 * Called on core init/fail.
 *
 * @param cls service closure
 * @param identity the public identity of this peer
 */
static void
core_init (void *cls,
           const struct GNUNET_PeerIdentity *identity)
{
  if (NULL == identity)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                "Connection to core FAILED!\n");
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
  my_identity = *identity;
}


/**
 * Called when another peer wants to do a set operation with the
 * local peer. If a listen error occurs, the 'request' is NULL.
 *
 * @param cls closure
 * @param other_peer the other peer
 * @param context_msg message with application specific information from
 *        the other peer
 * @param request request from the other peer (never NULL), use GNUNET_SET_accept()
 *        to accept it, otherwise the request will be refused
 *        Note that we can't just return value from the listen callback,
 *        as it is also necessary to specify the set we want to do the
 *        operation with, whith sometimes can be derived from the context
 *        message. It's necessary to specify the timeout.
 */
static void
handle_revocation_union_request (void *cls,
                                 const struct GNUNET_PeerIdentity *other_peer,
                                 const struct GNUNET_MessageHeader *context_msg,
                                 struct GNUNET_SET_Request *request)
{
  struct PeerEntry *peer_entry;

  if (NULL == request)
  {
    GNUNET_break (0);
    return;
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received set exchange request from peer `%s'\n",
              GNUNET_i2s (other_peer));
  peer_entry = GNUNET_CONTAINER_multipeermap_get (peers,
                                                  other_peer);
  if (NULL == peer_entry)
  {
    peer_entry = new_peer_entry (other_peer);
  }
  if (NULL != peer_entry->so)
  {
    GNUNET_break_op (0);
    return;
  }
  peer_entry->so = GNUNET_SET_accept (request,
                                      GNUNET_SET_RESULT_ADDED,
                                      (struct GNUNET_SET_Option[]) { { 0 } },
                                      &add_revocation,
                                      peer_entry);
  if (GNUNET_OK !=
      GNUNET_SET_commit (peer_entry->so,
                         revocation_set))
  {
    GNUNET_break (0);
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
}


/**
 * Handle network size estimate clients.
 *
 * @param cls closure
 * @param server the initialized server
 * @param c configuration to use
 */
static void
run (void *cls,
     const struct GNUNET_CONFIGURATION_Handle *c,
     struct GNUNET_SERVICE_Handle *service)
{
  struct GNUNET_MQ_MessageHandler core_handlers[] = {
    GNUNET_MQ_hd_fixed_size (p2p_revoke,
                             GNUNET_MESSAGE_TYPE_REVOCATION_REVOKE,
                             struct RevokeMessage,
                             NULL),
    GNUNET_MQ_handler_end ()
  };
  char *fn;
  uint64_t left;
  struct RevokeMessage *rm;
  struct GNUNET_HashCode hc;

  GNUNET_CRYPTO_hash ("revocation-set-union-application-id",
                      strlen ("revocation-set-union-application-id"),
                      &revocation_set_union_app_id);
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_filename (c,
                                               "REVOCATION",
                                               "DATABASE",
                                               &fn))
  {
    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
                               "REVOCATION",
                               "DATABASE");
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
  cfg = c;
  revocation_map = GNUNET_CONTAINER_multihashmap_create (16,
                                                         GNUNET_NO);
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_number (cfg,
                                             "REVOCATION",
                                             "WORKBITS",
                                             &revocation_work_required))
  {
    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
                               "REVOCATION",
                               "WORKBITS");
    GNUNET_SCHEDULER_shutdown ();
    GNUNET_free (fn);
    return;
  }
  if (revocation_work_required >= sizeof(struct GNUNET_HashCode) * 8)
  {
    GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR,
                               "REVOCATION",
                               "WORKBITS",
                               _ ("Value is too large.\n"));
    GNUNET_SCHEDULER_shutdown ();
    GNUNET_free (fn);
    return;
  }
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_time (cfg,
                                           "REVOCATION",
                                           "EPOCH_DURATION",
                                           &epoch_duration))
  {
    GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
                               "REVOCATION",
                               "EPOCH_DURATION");
    GNUNET_SCHEDULER_shutdown ();
    GNUNET_free (fn);
    return;
  }

  revocation_set = GNUNET_SET_create (cfg,
                                      GNUNET_SET_OPERATION_UNION);
  revocation_union_listen_handle
    = GNUNET_SET_listen (cfg,
                         GNUNET_SET_OPERATION_UNION,
                         &revocation_set_union_app_id,
                         &handle_revocation_union_request,
                         NULL);
  revocation_db = GNUNET_DISK_file_open (fn,
                                         GNUNET_DISK_OPEN_READWRITE
                                         | GNUNET_DISK_OPEN_CREATE,
                                         GNUNET_DISK_PERM_USER_READ
                                         | GNUNET_DISK_PERM_USER_WRITE
                                         | GNUNET_DISK_PERM_GROUP_READ
                                         | GNUNET_DISK_PERM_OTHER_READ);
  if (NULL == revocation_db)
  {
    GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR,
                               "REVOCATION",
                               "DATABASE",
                               _ ("Could not open revocation database file!"));
    GNUNET_SCHEDULER_shutdown ();
    GNUNET_free (fn);
    return;
  }
  if (GNUNET_OK !=
      GNUNET_DISK_file_size (fn, &left, GNUNET_YES, GNUNET_YES))
    left = 0;
  while (left > sizeof(struct RevokeMessage))
  {
    rm = GNUNET_new (struct RevokeMessage);
    if (sizeof(struct RevokeMessage) !=
        GNUNET_DISK_file_read (revocation_db,
                               rm,
                               sizeof(struct RevokeMessage)))
    {
      GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_ERROR,
                                "read",
                                fn);
      GNUNET_free (rm);
      GNUNET_SCHEDULER_shutdown ();
      GNUNET_free (fn);
      return;
    }
    GNUNET_break (0 == ntohl (rm->reserved));
    GNUNET_CRYPTO_hash (&rm->proof_of_work.key,
                        sizeof(struct GNUNET_CRYPTO_EcdsaPublicKey),
                        &hc);
    GNUNET_break (GNUNET_OK ==
                  GNUNET_CONTAINER_multihashmap_put (revocation_map,
                                                     &hc,
                                                     rm,
                                                     GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  }
  GNUNET_free (fn);

  GNUNET_SCHEDULER_add_shutdown (&shutdown_task,
                                 NULL);
  peers = GNUNET_CONTAINER_multipeermap_create (128,
                                                GNUNET_YES);
  /* Connect to core service and register core handlers */
  core_api = GNUNET_CORE_connect (cfg,    /* Main configuration */
                                  NULL,       /* Closure passed to functions */
                                  &core_init,    /* Call core_init once connected */
                                  &handle_core_connect,  /* Handle connects */
                                  &handle_core_disconnect,       /* Handle disconnects */
                                  core_handlers);        /* Register these handlers */
  if (NULL == core_api)
  {
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
  stats = GNUNET_STATISTICS_create ("revocation",
                                    cfg);
}


/**
 * Define "main" method using service macro.
 */
GNUNET_SERVICE_MAIN
  ("revocation",
  GNUNET_SERVICE_OPTION_NONE,
  &run,
  &client_connect_cb,
  &client_disconnect_cb,
  NULL,
  GNUNET_MQ_hd_fixed_size (query_message,
                           GNUNET_MESSAGE_TYPE_REVOCATION_QUERY,
                           struct QueryMessage,
                           NULL),
  GNUNET_MQ_hd_fixed_size (revoke_message,
                           GNUNET_MESSAGE_TYPE_REVOCATION_REVOKE,
                           struct RevokeMessage,
                           NULL),
  GNUNET_MQ_handler_end ());


#if defined(__linux__) && defined(__GLIBC__)
#include <malloc.h>

/**
 * MINIMIZE heap size (way below 128k) since this process doesn't need much.
 */
void __attribute__ ((constructor))
GNUNET_REVOCATION_memory_init ()
{
  mallopt (M_TRIM_THRESHOLD, 4 * 1024);
  mallopt (M_TOP_PAD, 1 * 1024);
  malloc_trim (0);
}


#endif


/* end of gnunet-service-revocation.c */