summaryrefslogtreecommitdiff
path: root/src/cadet/gnunet-service-cadet_core.c
blob: ec70a968b3d8d3bf09b8297bff4418b866ecfd8a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
/*
     This file is part of GNUnet.
     Copyright (C) 2017 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 cadet/gnunet-service-cadet_core.c
 * @brief cadet service; interaction with CORE service
 * @author Bartlomiej Polot
 * @author Christian Grothoff
 *
 * All functions in this file should use the prefix GCO (Gnunet Cadet cOre (bottom))
 *
 * TODO:
 * - Optimization: given BROKEN messages, destroy paths (?)
 */
#include "platform.h"
#include "gnunet-service-cadet_core.h"
#include "gnunet-service-cadet_paths.h"
#include "gnunet-service-cadet_peer.h"
#include "gnunet-service-cadet_connection.h"
#include "gnunet-service-cadet_tunnels.h"
#include "gnunet_core_service.h"
#include "gnunet_statistics_service.h"
#include "cadet_protocol.h"

#define LOG(level, ...) GNUNET_log_from (level, "cadet-cor", __VA_ARGS__)

/**
 * Information we keep per direction for a route.
 */
struct RouteDirection;

/**
 * Set of CadetRoutes that have exactly the same number of messages
 * in their buffer.  Used so we can efficiently find all of those
 * routes that have the current maximum of messages in the buffer (in
 * case we have to purge).
 */
struct Rung
{

  /**
   * Rung of RouteDirections with one more buffer entry each.
   */
  struct Rung *next;

  /**
   * Rung of RouteDirections with one less buffer entry each.
   */
  struct Rung *prev;

  /**
   * DLL of route directions with a number of buffer entries matching this rung.
   */
  struct RouteDirection *rd_head;

  /**
   * DLL of route directions with a number of buffer entries matching this rung.
   */
  struct RouteDirection *rd_tail;

  /**
   * Total number of route directions in this rung.
   */
  unsigned int num_routes;

  /**
   * Number of messages route directions at this rung have
   * in their buffer.
   */
  unsigned int rung_off;
};


/**
 * Information we keep per direction for a route.
 */
struct RouteDirection
{

  /**
   * DLL of other route directions within the same `struct Rung`.
   */
  struct RouteDirection *prev;

  /**
   * DLL of other route directions within the same `struct Rung`.
   */
  struct RouteDirection *next;

  /**
   * Rung of this route direction (matches length of the buffer DLL).
   */
  struct Rung *rung;

  /**
   * Head of DLL of envelopes we have in the buffer for this direction.
   */
  struct GNUNET_MQ_Envelope *env_head;

  /**
   * Tail of DLL of envelopes we have in the buffer for this direction.
   */
  struct GNUNET_MQ_Envelope *env_tail;

  /**
   * Target peer.
   */
  struct CadetPeer *hop;

  /**
   * Route this direction is part of.
   */
  struct CadetRoute *my_route;

  /**
   * Message queue manager for @e hop.
   */
  struct GCP_MessageQueueManager *mqm;

  /**
   * Is @e mqm currently ready for transmission?
   */
  int is_ready;
};


/**
 * Description of a segment of a `struct CadetConnection` at the
 * intermediate peers.  Routes are basically entries in a peer's
 * routing table for forwarding traffic.  At both endpoints, the
 * routes are terminated by a `struct CadetConnection`, which knows
 * the complete `struct CadetPath` that is formed by the individual
 * routes.
 */
struct CadetRoute
{

  /**
   * Information about the next hop on this route.
   */
  struct RouteDirection next;

  /**
   * Information about the previous hop on this route.
   */
  struct RouteDirection prev;

  /**
   * Unique identifier for the connection that uses this route.
   */
  struct GNUNET_CADET_ConnectionTunnelIdentifier cid;

  /**
   * When was this route last in use?
   */
  struct GNUNET_TIME_Absolute last_use;

  /**
   * Position of this route in the #route_heap.
   */
  struct GNUNET_CONTAINER_HeapNode *hn;
};


/**
 * Handle to the CORE service.
 */
static struct GNUNET_CORE_Handle *core;

/**
 * Routes on which this peer is an intermediate.
 */
static struct GNUNET_CONTAINER_MultiShortmap *routes;

/**
 * Heap of routes, MIN-sorted by last activity.
 */
static struct GNUNET_CONTAINER_Heap *route_heap;

/**
 * Rung zero (always pointed to by #rung_head).
 */
static struct Rung rung_zero;

/**
 * DLL of rungs, with the head always point to a rung of
 * route directions with no messages in the queue.
 */
static struct Rung *rung_head = &rung_zero;

/**
 * Tail of the #rung_head DLL.
 */
static struct Rung *rung_tail = &rung_zero;

/**
 * Maximum number of concurrent routes this peer will support.
 */
static unsigned long long max_routes;

/**
 * Maximum number of envelopes we will buffer at this peer.
 */
static unsigned long long max_buffers;

/**
 * Current number of envelopes we have buffered at this peer.
 */
static unsigned long long cur_buffers;

/**
 * Task to timeout routes.
 */
static struct GNUNET_SCHEDULER_Task *timeout_task;


/**
 * Get the route corresponding to a hash.
 *
 * @param cid hash generated from the connection identifier
 */
static struct CadetRoute *
get_route (const struct GNUNET_CADET_ConnectionTunnelIdentifier *cid)
{
  return GNUNET_CONTAINER_multishortmap_get (routes,
                                             &cid->connection_of_tunnel);
}


/**
 * Lower the rung in which @a dir is by 1.
 *
 * @param dir direction to lower in rung.
 */
static void
lower_rung (struct RouteDirection *dir)
{
  struct Rung *rung = dir->rung;
  struct Rung *prev;

  GNUNET_CONTAINER_DLL_remove (rung->rd_head, rung->rd_tail, dir);
  prev = rung->prev;
  GNUNET_assert (NULL != prev);
  if (prev->rung_off != rung->rung_off - 1)
  {
    prev = GNUNET_new (struct Rung);
    prev->rung_off = rung->rung_off - 1;
    GNUNET_CONTAINER_DLL_insert_after (rung_head, rung_tail, rung->prev, prev);
  }
  GNUNET_assert (NULL != prev);
  GNUNET_CONTAINER_DLL_insert (prev->rd_head, prev->rd_tail, dir);
  dir->rung = prev;
}


/**
 * Discard the buffer @a env from the route direction @a dir and
 * move @a dir down a rung.
 *
 * @param dir direction that contains the @a env in the buffer
 * @param env envelope to discard
 */
static void
discard_buffer (struct RouteDirection *dir, struct GNUNET_MQ_Envelope *env)
{
  GNUNET_MQ_dll_remove (&dir->env_head, &dir->env_tail, env);
  cur_buffers--;
  GNUNET_MQ_discard (env);
  lower_rung (dir);
  GNUNET_STATISTICS_set (stats, "# buffer use", cur_buffers, GNUNET_NO);
}


/**
 * Discard all messages from the highest rung, to make space.
 */
static void
discard_all_from_rung_tail ()
{
  struct Rung *tail = rung_tail;
  struct RouteDirection *dir;

  while (NULL != (dir = tail->rd_head))
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Queue full due new message %s on connection %s, dropping old message\n",
         GNUNET_sh2s (&dir->my_route->cid.connection_of_tunnel));
    GNUNET_STATISTICS_update (stats,
                              "# messages dropped due to full buffer",
                              1,
                              GNUNET_NO);
    discard_buffer (dir, dir->env_head);
  }
  GNUNET_CONTAINER_DLL_remove (rung_head, rung_tail, tail);
  GNUNET_free (tail);
}


/**
 * We message @a msg from @a prev.  Find its route by @a cid and
 * forward to the next hop.  Drop and signal broken route if we do not
 * have a route.
 *
 * @param prev previous hop (sender)
 * @param cid connection identifier, tells us which route to use
 * @param msg the message to forward
 */
static void
route_message (struct CadetPeer *prev,
               const struct GNUNET_CADET_ConnectionTunnelIdentifier *cid,
               const struct GNUNET_MessageHeader *msg,
               const enum GNUNET_MQ_PriorityPreferences priority)
{
  struct CadetRoute *route;
  struct RouteDirection *dir;
  struct Rung *rung;
  struct Rung *nxt;
  struct GNUNET_MQ_Envelope *env;

  route = get_route (cid);
  if (NULL == route)
  {
    struct GNUNET_MQ_Envelope *env;
    struct GNUNET_CADET_ConnectionBrokenMessage *bm;

    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Failed to route message of type %u from %s on connection %s: no route\n",
         ntohs (msg->type),
         GCP_2s (prev),
         GNUNET_sh2s (&cid->connection_of_tunnel));
    switch (ntohs (msg->type))
    {
    case GNUNET_MESSAGE_TYPE_CADET_CONNECTION_DESTROY:
    case GNUNET_MESSAGE_TYPE_CADET_CONNECTION_BROKEN:
      /* No need to respond to these! */
      return;
    }
    env = GNUNET_MQ_msg (bm, GNUNET_MESSAGE_TYPE_CADET_CONNECTION_BROKEN);
    bm->cid = *cid;
    bm->peer1 = my_full_id;
    GCP_send_ooo (prev, env);
    return;
  }
  route->last_use = GNUNET_TIME_absolute_get ();
  GNUNET_CONTAINER_heap_update_cost (route->hn, route->last_use.abs_value_us);
  dir = (prev == route->prev.hop) ? &route->next : &route->prev;
  if (GNUNET_YES == dir->is_ready)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Routing message of type %u from %s to %s on connection %s\n",
         ntohs (msg->type),
         GCP_2s (prev),
         GNUNET_i2s (GCP_get_id (dir->hop)),
         GNUNET_sh2s (&cid->connection_of_tunnel));
    dir->is_ready = GNUNET_NO;
    GCP_send (dir->mqm, GNUNET_MQ_msg_copy (msg));
    return;
  }
  /* Check if low latency is required and if the previous message was
     unreliable; if so, make sure we only queue one message per
     direction (no buffering). */
  if ((0 != (priority & GNUNET_MQ_PREF_LOW_LATENCY)) &&
      (NULL != dir->env_head) &&
      (0 ==
       (GNUNET_MQ_env_get_options (dir->env_head) & GNUNET_MQ_PREF_UNRELIABLE)))
    discard_buffer (dir, dir->env_head);
  /* Check for duplicates */
  for (const struct GNUNET_MQ_Envelope *env = dir->env_head; NULL != env;
       env = GNUNET_MQ_env_next (env))
  {
    const struct GNUNET_MessageHeader *hdr = GNUNET_MQ_env_get_msg (env);

    if ((hdr->size == msg->size) && (0 == memcmp (hdr, msg, ntohs (msg->size))))
    {
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Received duplicate of message already in buffer, dropping\n");
      GNUNET_STATISTICS_update (stats,
                                "# messages dropped due to duplicate in buffer",
                                1,
                                GNUNET_NO);
      return;
    }
  }

  rung = dir->rung;
  if (cur_buffers == max_buffers)
  {
    /* Need to make room. */
    if (NULL != rung->next)
    {
      /* Easy case, drop messages from route directions in highest rung */
      discard_all_from_rung_tail ();
    }
    else
    {
      /* We are in the highest rung, drop our own! */
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Queue full due new message %s on connection %s, dropping old message\n",
           GNUNET_sh2s (&dir->my_route->cid.connection_of_tunnel));
      GNUNET_STATISTICS_update (stats,
                                "# messages dropped due to full buffer",
                                1,
                                GNUNET_NO);
      discard_buffer (dir, dir->env_head);
      rung = dir->rung;
    }
  }
  /* remove 'dir' from current rung */
  GNUNET_CONTAINER_DLL_remove (rung->rd_head, rung->rd_tail, dir);
  /* make 'nxt' point to the next higher rung, create if necessary */
  nxt = rung->next;
  if ((NULL == nxt) || (rung->rung_off + 1 != nxt->rung_off))
  {
    nxt = GNUNET_new (struct Rung);
    nxt->rung_off = rung->rung_off + 1;
    GNUNET_CONTAINER_DLL_insert_after (rung_head, rung_tail, rung, nxt);
  }
  /* insert 'dir' into next higher rung */
  GNUNET_CONTAINER_DLL_insert (nxt->rd_head, nxt->rd_tail, dir);
  dir->rung = nxt;

  /* add message into 'dir' buffer */
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Queueing new message of type %u from %s to %s on connection %s\n",
       ntohs (msg->type),
       GCP_2s (prev),
       GNUNET_i2s (GCP_get_id (dir->hop)),
       GNUNET_sh2s (&cid->connection_of_tunnel));
  env = GNUNET_MQ_msg_copy (msg);
  GNUNET_MQ_env_set_options (env, priority);
  if ((0 != (priority & GNUNET_MQ_PREF_LOW_LATENCY)) &&
      (0 != (priority & GNUNET_MQ_PREF_OUT_OF_ORDER)) &&
      (NULL != dir->env_head) &&
      (0 == (GNUNET_MQ_env_get_options (dir->env_head) &
             GNUNET_MQ_PREF_LOW_LATENCY)))
    GNUNET_MQ_dll_insert_head (&dir->env_head, &dir->env_tail, env);
  else
    GNUNET_MQ_dll_insert_tail (&dir->env_head, &dir->env_tail, env);
  cur_buffers++;
  GNUNET_STATISTICS_set (stats, "# buffer use", cur_buffers, GNUNET_NO);
  /* Clean up 'rung' if now empty (and not head) */
  if ((NULL == rung->rd_head) && (rung != rung_head))
  {
    GNUNET_CONTAINER_DLL_remove (rung_head, rung_tail, rung);
    GNUNET_free (rung);
  }
}


/**
 * Check if the create_connection message has the appropriate size.
 *
 * @param cls Closure (unused).
 * @param msg Message to check.
 *
 * @return #GNUNET_YES if size is correct, #GNUNET_NO otherwise.
 */
static int
check_connection_create (void *cls,
                         const struct GNUNET_CADET_ConnectionCreateMessage *msg)
{
  uint16_t size = ntohs (msg->header.size) - sizeof (*msg);

  if (0 != (size % sizeof (struct GNUNET_PeerIdentity)))
  {
    GNUNET_break_op (0);
    return GNUNET_NO;
  }
  return GNUNET_YES;
}


/**
 * Free internal data of a route direction.
 *
 * @param dir direction to destroy (do NOT free memory of 'dir' itself)
 */
static void
destroy_direction (struct RouteDirection *dir)
{
  struct GNUNET_MQ_Envelope *env;

  while (NULL != (env = dir->env_head))
  {
    GNUNET_STATISTICS_update (stats,
                              "# messages dropped due to route destruction",
                              1,
                              GNUNET_NO);
    discard_buffer (dir, env);
  }
  if (NULL != dir->mqm)
  {
    GCP_request_mq_cancel (dir->mqm, NULL);
    dir->mqm = NULL;
  }
  GNUNET_CONTAINER_DLL_remove (rung_head->rd_head, rung_head->rd_tail, dir);
}


/**
 * Destroy our state for @a route.
 *
 * @param route route to destroy
 */
static void
destroy_route (struct CadetRoute *route)
{
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Destroying route from %s to %s of connection %s\n",
       GNUNET_i2s (GCP_get_id (route->prev.hop)),
       GNUNET_i2s2 (GCP_get_id (route->next.hop)),
       GNUNET_sh2s (&route->cid.connection_of_tunnel));
  GNUNET_assert (route == GNUNET_CONTAINER_heap_remove_node (route->hn));
  GNUNET_assert (
    GNUNET_YES ==
    GNUNET_CONTAINER_multishortmap_remove (routes,
                                           &route->cid.connection_of_tunnel,
                                           route));
  GNUNET_STATISTICS_set (stats,
                         "# routes",
                         GNUNET_CONTAINER_multishortmap_size (routes),
                         GNUNET_NO);
  destroy_direction (&route->prev);
  destroy_direction (&route->next);
  GNUNET_free (route);
}


/**
 * Send message that a route is broken between @a peer1 and @a peer2.
 *
 * @param target where to send the message
 * @param cid connection identifier to use
 * @param peer1 one of the peers where a link is broken
 * @param peer2 another one of the peers where a link is broken
 */
static void
send_broken (struct RouteDirection *target,
             const struct GNUNET_CADET_ConnectionTunnelIdentifier *cid,
             const struct GNUNET_PeerIdentity *peer1,
             const struct GNUNET_PeerIdentity *peer2)
{
  struct GNUNET_MQ_Envelope *env;
  struct GNUNET_CADET_ConnectionBrokenMessage *bm;

  if (NULL == target->mqm)
    return; /* Can't send notification, connection is down! */
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Notifying %s about BROKEN route at %s-%s of connection %s\n",
       GCP_2s (target->hop),
       GNUNET_i2s (peer1),
       GNUNET_i2s2 (peer2),
       GNUNET_sh2s (&cid->connection_of_tunnel));

  env = GNUNET_MQ_msg (bm, GNUNET_MESSAGE_TYPE_CADET_CONNECTION_BROKEN);
  bm->cid = *cid;
  if (NULL != peer1)
    bm->peer1 = *peer1;
  if (NULL != peer2)
    bm->peer2 = *peer2;
  GCP_request_mq_cancel (target->mqm, env);
  target->mqm = NULL;
}


/**
 * Function called to check if any routes have timed out, and if
 * so, to clean them up.  Finally, schedules itself again at the
 * earliest time where there might be more work.
 *
 * @param cls NULL
 */
static void
timeout_cb (void *cls)
{
  struct CadetRoute *r;
  struct GNUNET_TIME_Relative linger;
  struct GNUNET_TIME_Absolute exp;

  timeout_task = NULL;
  linger = GNUNET_TIME_relative_multiply (keepalive_period, 3);
  while (NULL != (r = GNUNET_CONTAINER_heap_peek (route_heap)))
  {
    exp = GNUNET_TIME_absolute_add (r->last_use, linger);
    if (0 != GNUNET_TIME_absolute_get_remaining (exp).rel_value_us)
    {
      /* Route not yet timed out, wait until it does. */
      timeout_task = GNUNET_SCHEDULER_add_at (exp, &timeout_cb, NULL);
      return;
    }
    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                "Sending BROKEN due to timeout (%s was last use, %s linger)\n",
                GNUNET_STRINGS_absolute_time_to_string (r->last_use),
                GNUNET_STRINGS_relative_time_to_string (linger, GNUNET_YES));
    send_broken (&r->prev, &r->cid, NULL, NULL);
    send_broken (&r->next, &r->cid, NULL, NULL);
    destroy_route (r);
  }
  /* No more routes left, so no need for a #timeout_task */
}


/**
 * Function called when the message queue to the previous hop
 * becomes available/unavailable.  We expect this function to
 * be called immediately when we register, and then again
 * later if the connection ever goes down.
 *
 * @param cls the `struct RouteDirection`
 * @param available #GNUNET_YES if sending is now possible,
 *                  #GNUNET_NO if sending is no longer possible
 *                  #GNUNET_SYSERR if sending is no longer possible
 *                                 and the last envelope was discarded
 */
static void
dir_ready_cb (void *cls, int ready)
{
  struct RouteDirection *dir = cls;
  struct CadetRoute *route = dir->my_route;
  struct RouteDirection *odir;

  if (GNUNET_YES == ready)
  {
    struct GNUNET_MQ_Envelope *env;

    dir->is_ready = GNUNET_YES;
    if (NULL != (env = dir->env_head))
    {
      GNUNET_MQ_dll_remove (&dir->env_head, &dir->env_tail, env);
      cur_buffers--;
      GNUNET_STATISTICS_set (stats, "# buffer use", cur_buffers, GNUNET_NO);
      lower_rung (dir);
      dir->is_ready = GNUNET_NO;
      GCP_send (dir->mqm, env);
    }
    return;
  }
  odir = (dir == &route->next) ? &route->prev : &route->next;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Sending BROKEN due to MQ going down\n");
  send_broken (&route->next, &route->cid, GCP_get_id (odir->hop), &my_full_id);
  destroy_route (route);
}


/**
 * Initialize one of the directions of a route.
 *
 * @param route route the direction belongs to
 * @param dir direction to initialize
 * @param hop next hop on in the @a dir
 */
static void
dir_init (struct RouteDirection *dir,
          struct CadetRoute *route,
          struct CadetPeer *hop)
{
  dir->hop = hop;
  dir->my_route = route;
  dir->mqm = GCP_request_mq (hop, &dir_ready_cb, dir);
  GNUNET_CONTAINER_DLL_insert (rung_head->rd_head, rung_head->rd_tail, dir);
  dir->rung = rung_head;
  GNUNET_assert (GNUNET_YES == dir->is_ready);
}


/**
 * We could not create the desired route.  Send a
 * #GNUNET_MESSAGE_TYPE_CADET_CONNECTION_BROKEN
 * message to @a target.
 *
 * @param target who should receive the message
 * @param cid identifier of the connection/route that failed
 * @param failure_at neighbour with which we failed to route,
 *        or NULL.
 */
static void
send_broken_without_mqm (
  struct CadetPeer *target,
  const struct GNUNET_CADET_ConnectionTunnelIdentifier *cid,
  const struct GNUNET_PeerIdentity *failure_at)
{
  struct GNUNET_MQ_Envelope *env;
  struct GNUNET_CADET_ConnectionBrokenMessage *bm;

  env = GNUNET_MQ_msg (bm, GNUNET_MESSAGE_TYPE_CADET_CONNECTION_BROKEN);
  bm->cid = *cid;
  bm->peer1 = my_full_id;
  if (NULL != failure_at)
    bm->peer2 = *failure_at;
  GCP_send_ooo (target, env);
}


/**
 * Handle for #GNUNET_MESSAGE_TYPE_CADET_CONNECTION_CREATE
 *
 * @param cls Closure (CadetPeer for neighbor that sent the message).
 * @param msg Message itself.
 */
static void
handle_connection_create (
  void *cls,
  const struct GNUNET_CADET_ConnectionCreateMessage *msg)
{
  struct CadetPeer *sender = cls;
  struct CadetPeer *next;
  const struct GNUNET_PeerIdentity *pids =
    (const struct GNUNET_PeerIdentity *) &msg[1];
  struct CadetRoute *route;
  uint16_t size = ntohs (msg->header.size) - sizeof (*msg);
  unsigned int path_length;
  unsigned int off;

  path_length = size / sizeof (struct GNUNET_PeerIdentity);
  if (0 == path_length)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Dropping CADET_CONNECTION_CREATE with empty path\n");
    GNUNET_break_op (0);
    return;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Handling CADET_CONNECTION_CREATE from %s for CID %s with %u hops\n",
       GCP_2s (sender),
       GNUNET_sh2s (&msg->cid.connection_of_tunnel),
       path_length);
  /* Check for loops */
  {
    struct GNUNET_CONTAINER_MultiPeerMap *map;

    map = GNUNET_CONTAINER_multipeermap_create (path_length * 2, GNUNET_YES);
    GNUNET_assert (NULL != map);
    for (unsigned int i = 0; i < path_length; i++)
    {
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "CADET_CONNECTION_CREATE has peer %s at offset %u\n",
           GNUNET_i2s (&pids[i]),
           i);
      if (GNUNET_SYSERR == GNUNET_CONTAINER_multipeermap_put (
                             map,
                             &pids[i],
                             NULL,
                             GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY))
      {
        /* bogus request */
        GNUNET_CONTAINER_multipeermap_destroy (map);
        LOG (GNUNET_ERROR_TYPE_DEBUG,
             "Dropping CADET_CONNECTION_CREATE with cyclic path\n");
        GNUNET_break_op (0);
        return;
      }
    }
    GNUNET_CONTAINER_multipeermap_destroy (map);
  }
  /* Initiator is at offset 0, find us */
  for (off = 1; off < path_length; off++)
    if (0 == GNUNET_memcmp (&my_full_id, &pids[off]))
      break;
  if (off == path_length)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Dropping CADET_CONNECTION_CREATE without us in the path\n");
    GNUNET_break_op (0);
    return;
  }
  /* Check previous hop */
  if (sender != GCP_get (&pids[off - 1], GNUNET_NO))
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Dropping CADET_CONNECTION_CREATE without sender at previous hop in the path\n");
    GNUNET_break_op (0);
    return;
  }
  if (NULL != (route = get_route (&msg->cid)))
  {
    /* Duplicate CREATE, pass it on, previous one might have been lost! */

    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Passing on duplicate CADET_CONNECTION_CREATE message on connection %s\n",
         GNUNET_sh2s (&msg->cid.connection_of_tunnel));
    route_message (sender,
                   &msg->cid,
                   &msg->header,
                   GNUNET_MQ_PRIO_CRITICAL_CONTROL |
                     GNUNET_MQ_PREF_LOW_LATENCY);
    return;
  }
  if (off == path_length - 1)
  {
    /* We are the destination, create connection */
    struct CadetConnection *cc;
    struct CadetPeerPath *path;
    struct CadetPeer *origin;

    cc = GCC_lookup (&msg->cid);
    if (NULL != cc)
    {
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Received duplicate CADET_CONNECTION_CREATE message on connection %s\n",
           GNUNET_sh2s (&msg->cid.connection_of_tunnel));
      GCC_handle_duplicate_create (cc);
      return;
    }

    origin = GCP_get (&pids[0], GNUNET_YES);
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "I am destination for CADET_CONNECTION_CREATE message from %s for connection %s, building inverse path\n",
         GCP_2s (origin),
         GNUNET_sh2s (&msg->cid.connection_of_tunnel));
    path = GCPP_get_path_from_route (path_length - 1, pids);
    if (GNUNET_OK !=
        GCT_add_inbound_connection (GCP_get_tunnel (origin, GNUNET_YES),
                                    &msg->cid,
                                    path))
    {
      /* Send back BROKEN: duplicate connection on the same path,
         we will use the other one. */
      LOG (GNUNET_ERROR_TYPE_DEBUG,
           "Received CADET_CONNECTION_CREATE from %s for %s, but %s already has a connection. Sending BROKEN\n",
           GCP_2s (sender),
           GNUNET_sh2s (&msg->cid.connection_of_tunnel),
           GCPP_2s (path));
      send_broken_without_mqm (sender, &msg->cid, NULL);
      return;
    }
    return;
  }
  /* We are merely a hop on the way, check if we can support the route */
  next = GCP_get (&pids[off + 1], GNUNET_NO);
  if ((NULL == next) || (GNUNET_NO == GCP_has_core_connection (next)))
  {
    /* unworkable, send back BROKEN notification */
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Received CADET_CONNECTION_CREATE from %s for %s. Next hop %s:%u is down. Sending BROKEN\n",
         GCP_2s (sender),
         GNUNET_sh2s (&msg->cid.connection_of_tunnel),
         GNUNET_i2s (&pids[off + 1]),
         off + 1);
    send_broken_without_mqm (sender, &msg->cid, &pids[off + 1]);
    return;
  }
  if (max_routes <= GNUNET_CONTAINER_multishortmap_size (routes))
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Received CADET_CONNECTION_CREATE from %s for %s. We have reached our route limit. Sending BROKEN\n",
         GCP_2s (sender),
         GNUNET_sh2s (&msg->cid.connection_of_tunnel));
    send_broken_without_mqm (sender, &msg->cid, &pids[off - 1]);
    return;
  }

  /* Workable route, create routing entry */
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Received CADET_CONNECTION_CREATE from %s for %s. Next hop %s:%u is up. Creating route\n",
       GCP_2s (sender),
       GNUNET_sh2s (&msg->cid.connection_of_tunnel),
       GNUNET_i2s (&pids[off + 1]),
       off + 1);
  route = GNUNET_new (struct CadetRoute);
  route->cid = msg->cid;
  route->last_use = GNUNET_TIME_absolute_get ();
  dir_init (&route->prev, route, sender);
  dir_init (&route->next, route, next);
  GNUNET_assert (GNUNET_OK ==
                 GNUNET_CONTAINER_multishortmap_put (
                   routes,
                   &route->cid.connection_of_tunnel,
                   route,
                   GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  GNUNET_STATISTICS_set (stats,
                         "# routes",
                         GNUNET_CONTAINER_multishortmap_size (routes),
                         GNUNET_NO);
  route->hn = GNUNET_CONTAINER_heap_insert (route_heap,
                                            route,
                                            route->last_use.abs_value_us);
  if (NULL == timeout_task)
    timeout_task =
      GNUNET_SCHEDULER_add_delayed (GNUNET_TIME_relative_multiply (keepalive_period,
                                                                   3),
                                    &timeout_cb,
                                    NULL);
  /* also pass CREATE message along to next hop */
  route_message (sender,
                 &msg->cid,
                 &msg->header,
                 GNUNET_MQ_PRIO_CRITICAL_CONTROL | GNUNET_MQ_PREF_LOW_LATENCY);
}


/**
 * Handle for #GNUNET_MESSAGE_TYPE_CADET_CONNECTION_CREATE_ACK
 *
 * @param cls Closure (CadetPeer for neighbor that sent the message).
 * @param msg Message itself.
 */
static void
handle_connection_create_ack (
  void *cls,
  const struct GNUNET_CADET_ConnectionCreateAckMessage *msg)
{
  struct CadetPeer *peer = cls;
  struct CadetConnection *cc;

  /* First, check if ACK belongs to a connection that ends here. */
  cc = GCC_lookup (&msg->cid);
  if (NULL != cc)
  {
    /* verify ACK came from the right direction */
    unsigned int len;
    struct CadetPeerPath *path = GCC_get_path (cc, &len);

    if (peer != GCPP_get_peer_at_offset (path, 0))
    {
      /* received ACK from unexpected direction, ignore! */
      GNUNET_break_op (0);
      return;
    }
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Received CONNECTION_CREATE_ACK for connection %s.\n",
         GNUNET_sh2s (&msg->cid.connection_of_tunnel));
    GCC_handle_connection_create_ack (cc);
    return;
  }

  /* We're just an intermediary peer, route the message along its path */
  route_message (peer,
                 &msg->cid,
                 &msg->header,
                 GNUNET_MQ_PRIO_CRITICAL_CONTROL | GNUNET_MQ_PREF_LOW_LATENCY);
}


/**
 * Handle for #GNUNET_MESSAGE_TYPE_CADET_CONNECTION_BROKEN
 *
 * @param cls Closure (CadetPeer for neighbor that sent the message).
 * @param msg Message itself.
 * @deprecated duplicate logic with #handle_destroy(); dedup!
 */
static void
handle_connection_broken (
  void *cls,
  const struct GNUNET_CADET_ConnectionBrokenMessage *msg)
{
  struct CadetPeer *peer = cls;
  struct CadetConnection *cc;
  struct CadetRoute *route;

  /* First, check if message belongs to a connection that ends here. */
  cc = GCC_lookup (&msg->cid);
  if (NULL != cc)
  {
    /* verify message came from the right direction */
    unsigned int len;
    struct CadetPeerPath *path = GCC_get_path (cc, &len);

    if (peer != GCPP_get_peer_at_offset (path, 0))
    {
      /* received message from unexpected direction, ignore! */
      GNUNET_break_op (0);
      return;
    }
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Received CONNECTION_BROKEN for connection %s. Destroying it.\n",
         GNUNET_sh2s (&msg->cid.connection_of_tunnel));
    GCC_destroy_without_core (cc);

    /* FIXME: also destroy the path up to the specified link! */
    return;
  }

  /* We're just an intermediary peer, route the message along its path */
  route_message (peer,
                 &msg->cid,
                 &msg->header,
                 GNUNET_MQ_PREF_LOW_LATENCY | GNUNET_MQ_PRIO_CRITICAL_CONTROL);
  route = get_route (&msg->cid);
  if (NULL != route)
    destroy_route (route);
  /* FIXME: also destroy paths we MAY have up to the specified link! */
}


/**
 * Handle for #GNUNET_MESSAGE_TYPE_CADET_CONNECTION_DESTROY
 *
 * @param cls Closure (CadetPeer for neighbor that sent the message).
 * @param msg Message itself.
 */
static void
handle_connection_destroy (
  void *cls,
  const struct GNUNET_CADET_ConnectionDestroyMessage *msg)
{
  struct CadetPeer *peer = cls;
  struct CadetConnection *cc;
  struct CadetRoute *route;

  /* First, check if message belongs to a connection that ends here. */
  cc = GCC_lookup (&msg->cid);
  if (NULL != cc)
  {
    /* verify message came from the right direction */
    unsigned int len;
    struct CadetPeerPath *path = GCC_get_path (cc, &len);

    if (peer != GCPP_get_peer_at_offset (path, 0))
    {
      /* received message from unexpected direction, ignore! */
      GNUNET_break_op (0);
      return;
    }
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Received CONNECTION_DESTROY for connection %s. Destroying connection.\n",
         GNUNET_sh2s (&msg->cid.connection_of_tunnel));

    GCC_destroy_without_core (cc);
    return;
  }

  /* We're just an intermediary peer, route the message along its path */
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Received CONNECTION_DESTROY for connection %s. Destroying route.\n",
       GNUNET_sh2s (&msg->cid.connection_of_tunnel));
  route_message (peer,
                 &msg->cid,
                 &msg->header,
                 GNUNET_MQ_PREF_LOW_LATENCY | GNUNET_MQ_PRIO_CRITICAL_CONTROL);
  route = get_route (&msg->cid);
  if (NULL != route)
    destroy_route (route);
}


/**
 * Handle for #GNUNET_MESSAGE_TYPE_CADET_TUNNEL_KX
 *
 * @param cls Closure (CadetPeer for neighbor that sent the message).
 * @param msg Message itself.
 */
static void
handle_tunnel_kx (void *cls,
                  const struct GNUNET_CADET_TunnelKeyExchangeMessage *msg)
{
  struct CadetPeer *peer = cls;
  struct CadetConnection *cc;

  /* First, check if message belongs to a connection that ends here. */
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Routing KX with ephemeral %s on CID %s\n",
       GNUNET_e2s (&msg->ephemeral_key),
       GNUNET_sh2s (&msg->cid.connection_of_tunnel));


  cc = GCC_lookup (&msg->cid);
  if (NULL != cc)
  {
    /* verify message came from the right direction */
    unsigned int len;
    struct CadetPeerPath *path = GCC_get_path (cc, &len);

    if (peer != GCPP_get_peer_at_offset (path, 0))
    {
      /* received message from unexpected direction, ignore! */
      GNUNET_break_op (0);
      return;
    }
    GCC_handle_kx (cc, msg);
    return;
  }

  /* We're just an intermediary peer, route the message along its path */
  route_message (peer,
                 &msg->cid,
                 &msg->header,
                 GNUNET_MQ_PRIO_CRITICAL_CONTROL | GNUNET_MQ_PREF_LOW_LATENCY);
}


/**
 * Handle for #GNUNET_MESSAGE_TYPE_CADET_TUNNEL_KX_AUTH
 *
 * @param cls Closure (CadetPeer for neighbor that sent the message).
 * @param msg Message itself.
 */
static void
handle_tunnel_kx_auth (
  void *cls,
  const struct GNUNET_CADET_TunnelKeyExchangeAuthMessage *msg)
{
  struct CadetPeer *peer = cls;
  struct CadetConnection *cc;

  /* First, check if message belongs to a connection that ends here. */
  cc = GCC_lookup (&msg->kx.cid);
  if (NULL != cc)
  {
    /* verify message came from the right direction */
    unsigned int len;
    struct CadetPeerPath *path = GCC_get_path (cc, &len);

    if (peer != GCPP_get_peer_at_offset (path, 0))
    {
      /* received message from unexpected direction, ignore! */
      GNUNET_break_op (0);
      return;
    }
    GCC_handle_kx_auth (cc, msg);
    return;
  }

  /* We're just an intermediary peer, route the message along its path */
  route_message (peer,
                 &msg->kx.cid,
                 &msg->kx.header,
                 GNUNET_MQ_PRIO_CRITICAL_CONTROL | GNUNET_MQ_PREF_LOW_LATENCY);
}


/**
 * Check if the encrypted message has the appropriate size.
 *
 * @param cls Closure (unused).
 * @param msg Message to check.
 *
 * @return #GNUNET_YES if size is correct, #GNUNET_NO otherwise.
 */
static int
check_tunnel_encrypted (void *cls,
                        const struct GNUNET_CADET_TunnelEncryptedMessage *msg)
{
  return GNUNET_YES;
}


/**
 * Handle for #GNUNET_MESSAGE_TYPE_CADET_TUNNEL_ENCRYPTED.
 *
 * @param cls Closure (CadetPeer for neighbor that sent the message).
 * @param msg Message itself.
 */
static void
handle_tunnel_encrypted (void *cls,
                         const struct GNUNET_CADET_TunnelEncryptedMessage *msg)
{
  struct CadetPeer *peer = cls;
  struct CadetConnection *cc;

  /* First, check if message belongs to a connection that ends here. */
  cc = GCC_lookup (&msg->cid);
  if (NULL != cc)
  {
    /* verify message came from the right direction */
    unsigned int len;
    struct CadetPeerPath *path = GCC_get_path (cc, &len);

    if (peer != GCPP_get_peer_at_offset (path, 0))
    {
      /* received message from unexpected direction, ignore! */
      GNUNET_break_op (0);
      return;
    }
    GCC_handle_encrypted (cc, msg);
    return;
  }
  /* We're just an intermediary peer, route the message along its path */
  route_message (peer, &msg->cid, &msg->header, GNUNET_MQ_PRIO_BEST_EFFORT);
}


/**
 * Function called after #GNUNET_CORE_connect has succeeded (or failed
 * for good).  Note that the private key of the peer is intentionally
 * not exposed here; if you need it, your process should try to read
 * the private key file directly (which should work if you are
 * authorized...).  Implementations of this function must not call
 * #GNUNET_CORE_disconnect (other than by scheduling a new task to
 * do this later).
 *
 * @param cls closure
 * @param my_identity ID of this peer, NULL if we failed
 */
static void
core_init_cb (void *cls, const struct GNUNET_PeerIdentity *my_identity)
{
  if (NULL == my_identity)
  {
    GNUNET_break (0);
    return;
  }
  GNUNET_break (0 == GNUNET_memcmp (my_identity, &my_full_id));
}


/**
 * Method called whenever a given peer connects.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 */
static void *
core_connect_cb (void *cls,
                 const struct GNUNET_PeerIdentity *peer,
                 struct GNUNET_MQ_Handle *mq)
{
  struct CadetPeer *cp;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "CORE connection to peer %s was established.\n",
       GNUNET_i2s (peer));
  cp = GCP_get (peer, GNUNET_YES);
  GCP_set_mq (cp, mq);
  return cp;
}


/**
 * Method called whenever a peer disconnects.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 */
static void
core_disconnect_cb (void *cls,
                    const struct GNUNET_PeerIdentity *peer,
                    void *peer_cls)
{
  struct CadetPeer *cp = peer_cls;

  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "CORE connection to peer %s went down.\n",
       GNUNET_i2s (peer));
  GCP_set_mq (cp, NULL);
}


/**
 * Initialize the CORE subsystem.
 *
 * @param c Configuration.
 */
void
GCO_init (const struct GNUNET_CONFIGURATION_Handle *c)
{
  struct GNUNET_MQ_MessageHandler handlers[] =
    {GNUNET_MQ_hd_var_size (connection_create,
                            GNUNET_MESSAGE_TYPE_CADET_CONNECTION_CREATE,
                            struct GNUNET_CADET_ConnectionCreateMessage,
                            NULL),
     GNUNET_MQ_hd_fixed_size (connection_create_ack,
                              GNUNET_MESSAGE_TYPE_CADET_CONNECTION_CREATE_ACK,
                              struct GNUNET_CADET_ConnectionCreateAckMessage,
                              NULL),
     GNUNET_MQ_hd_fixed_size (connection_broken,
                              GNUNET_MESSAGE_TYPE_CADET_CONNECTION_BROKEN,
                              struct GNUNET_CADET_ConnectionBrokenMessage,
                              NULL),
     GNUNET_MQ_hd_fixed_size (connection_destroy,
                              GNUNET_MESSAGE_TYPE_CADET_CONNECTION_DESTROY,
                              struct GNUNET_CADET_ConnectionDestroyMessage,
                              NULL),
     GNUNET_MQ_hd_fixed_size (tunnel_kx,
                              GNUNET_MESSAGE_TYPE_CADET_TUNNEL_KX,
                              struct GNUNET_CADET_TunnelKeyExchangeMessage,
                              NULL),
     GNUNET_MQ_hd_fixed_size (tunnel_kx_auth,
                              GNUNET_MESSAGE_TYPE_CADET_TUNNEL_KX_AUTH,
                              struct GNUNET_CADET_TunnelKeyExchangeAuthMessage,
                              NULL),
     GNUNET_MQ_hd_var_size (tunnel_encrypted,
                            GNUNET_MESSAGE_TYPE_CADET_TUNNEL_ENCRYPTED,
                            struct GNUNET_CADET_TunnelEncryptedMessage,
                            NULL),
     GNUNET_MQ_handler_end ()};

  if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_number (c,
                                                          "CADET",
                                                          "MAX_ROUTES",
                                                          &max_routes))
    max_routes = 5000;
  if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_number (c,
                                                          "CADET",
                                                          "MAX_MSGS_QUEUE",
                                                          &max_buffers))
    max_buffers = 10000;
  routes = GNUNET_CONTAINER_multishortmap_create (1024, GNUNET_NO);
  route_heap = GNUNET_CONTAINER_heap_create (GNUNET_CONTAINER_HEAP_ORDER_MIN);
  core = GNUNET_CORE_connect (c,
                              NULL,
                              &core_init_cb,
                              &core_connect_cb,
                              &core_disconnect_cb,
                              handlers);
}


/**
 * Shut down the CORE subsystem.
 */
void
GCO_shutdown ()
{
  if (NULL != core)
  {
    GNUNET_CORE_disconnect (core);
    core = NULL;
  }
  GNUNET_assert (0 == GNUNET_CONTAINER_multishortmap_size (routes));
  GNUNET_CONTAINER_multishortmap_destroy (routes);
  routes = NULL;
  GNUNET_CONTAINER_heap_destroy (route_heap);
  route_heap = NULL;
  if (NULL != timeout_task)
  {
    GNUNET_SCHEDULER_cancel (timeout_task);
    timeout_task = NULL;
  }
}

/* end of gnunet-cadet-service_core.c */