summaryrefslogtreecommitdiff
path: root/src/topology/gnunet-daemon-topology.c
blob: 261d825ea4e2e8d023c228088556f988bd65a100 (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
/*
     This file is part of GNUnet.
     Copyright (C) 2007-2016 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 topology/gnunet-daemon-topology.c
 * @brief code for maintaining the overlay topology
 * @author Christian Grothoff
 *
 * This daemon combines three functions:
 * - suggesting to ATS which peers we might want to connect to
 * - enforcing the F2F restrictions (by blacklisting)
 * - gossping HELLOs
 *
 * All three require similar information (who are our friends
 * impacts connectivity suggestions; connectivity suggestions
 * should consider blacklisting; connectivity suggestions
 * should consider available/known HELLOs; gossip requires
 * connectivity data; connectivity suggestions require
 * connectivity data), which is why they are combined in this
 * program.
 */
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_friends_lib.h"
#include "gnunet_constants.h"
#include "gnunet_core_service.h"
#include "gnunet_protocols.h"
#include "gnunet_peerinfo_service.h"
#include "gnunet_statistics_service.h"
#include "gnunet_transport_service.h"
#include "gnunet_ats_service.h"


/**
 * At what frequency do we sent HELLOs to a peer?
 */
#define HELLO_ADVERTISEMENT_MIN_FREQUENCY \
  GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 5)

/**
 * After what time period do we expire the HELLO Bloom filter?
 */
#define HELLO_ADVERTISEMENT_MIN_REPEAT_FREQUENCY \
  GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_HOURS, 4)


/**
 * Record for neighbours, friends and blacklisted peers.
 */
struct Peer
{
  /**
   * Which peer is this entry about?
   */
  struct GNUNET_PeerIdentity pid;

  /**
   * Our handle for transmitting to this peer; NULL
   * if peer is not connected.
   */
  struct GNUNET_MQ_Handle *mq;

  /**
   * Pointer to the HELLO message of this peer; can be NULL.
   */
  struct GNUNET_HELLO_Message *hello;

  /**
   * Bloom filter used to mark which peers already got the HELLO
   * from this peer.
   */
  struct GNUNET_CONTAINER_BloomFilter *filter;

  /**
   * Next time we are allowed to transmit a HELLO to this peer?
   */
  struct GNUNET_TIME_Absolute next_hello_allowed;

  /**
   * When should we reset the bloom filter of this entry?
   */
  struct GNUNET_TIME_Absolute filter_expiration;

  /**
   * ID of task we use to wait for the time to send the next HELLO
   * to this peer.
   */
  struct GNUNET_SCHEDULER_Task *hello_delay_task;

  /**
   * Handle for our connectivity suggestion for this peer.
   */
  struct GNUNET_ATS_ConnectivitySuggestHandle *sh;

  /**
   * How much would we like to connect to this peer?
   */
  uint32_t strength;

  /**
   * Is this peer listed here because it is a friend?
   */
  int is_friend;
};


/**
 * Our peerinfo notification context.  We use notification
 * to instantly learn about new peers as they are discovered.
 */
static struct GNUNET_PEERINFO_NotifyContext *peerinfo_notify;

/**
 * Our configuration.
 */
static const struct GNUNET_CONFIGURATION_Handle *cfg;

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

/**
 * Handle to the PEERINFO service.
 */
static struct GNUNET_PEERINFO_Handle *pi;

/**
 * Handle to the ATS service.
 */
static struct GNUNET_ATS_ConnectivityHandle *ats;

/**
 * Identity of this peer.
 */
static struct GNUNET_PeerIdentity my_identity;

/**
 * All of our friends, all of our current neighbours and all peers for
 * which we have HELLOs.  So pretty much everyone.  Maps peer identities
 * to `struct Peer *` values.
 */
static struct GNUNET_CONTAINER_MultiPeerMap *peers;

/**
 * Handle for reporting statistics.
 */
static struct GNUNET_STATISTICS_Handle *stats;

/**
 * Blacklist (NULL if we have none).
 */
static struct GNUNET_TRANSPORT_Blacklist *blacklist;

/**
 * Task scheduled to asynchronously reconsider adding/removing
 * peer connectivity suggestions.
 */
static struct GNUNET_SCHEDULER_Task *add_task;

/**
 * Active HELLO offering to transport service.
 */
static struct GNUNET_TRANSPORT_OfferHelloHandle *oh;

/**
 * Flag to disallow non-friend connections (pure F2F mode).
 */
static int friends_only;

/**
 * Minimum number of friends to have in the
 * connection set before we allow non-friends.
 */
static unsigned int minimum_friend_count;

/**
 * Number of peers (friends and others) that we are currently connected to.
 */
static unsigned int connection_count;

/**
 * Target number of connections.
 */
static unsigned int target_connection_count;

/**
 * Number of friends that we are currently connected to.
 */
static unsigned int friend_count;


/**
 * Function that decides if a connection is acceptable or not.
 * If we have a blacklist, only friends are allowed, so the check
 * is rather simple.
 *
 * @param cls closure
 * @param pid peer to approve or disapprove
 * @return #GNUNET_OK if the connection is allowed
 */
static int
blacklist_check (void *cls, const struct GNUNET_PeerIdentity *pid)
{
  struct Peer *pos;

  pos = GNUNET_CONTAINER_multipeermap_get (peers, pid);
  if ((NULL != pos) && (GNUNET_YES == pos->is_friend))
    return GNUNET_OK;
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# peers blacklisted"),
                            1,
                            GNUNET_NO);
  return GNUNET_SYSERR;
}


/**
 * Whitelist all peers that we blacklisted; we've passed
 * the minimum number of friends.
 */
static void
whitelist_peers ()
{
  if (NULL != blacklist)
  {
    GNUNET_TRANSPORT_blacklist_cancel (blacklist);
    blacklist = NULL;
  }
}


/**
 * Free all resources associated with the given peer.
 *
 * @param cls closure (not used)
 * @param pid identity of the peer
 * @param value peer to free
 * @return #GNUNET_YES (always: continue to iterate)
 */
static int
free_peer (void *cls, const struct GNUNET_PeerIdentity *pid, void *value)
{
  struct Peer *pos = value;

  GNUNET_break (NULL == pos->mq);
  GNUNET_break (GNUNET_OK ==
                GNUNET_CONTAINER_multipeermap_remove (peers, pid, pos));
  if (NULL != pos->hello_delay_task)
  {
    GNUNET_SCHEDULER_cancel (pos->hello_delay_task);
    pos->hello_delay_task = NULL;
  }
  if (NULL != pos->sh)
  {
    GNUNET_ATS_connectivity_suggest_cancel (pos->sh);
    pos->sh = NULL;
  }
  if (NULL != pos->hello)
  {
    GNUNET_free_non_null (pos->hello);
    pos->hello = NULL;
  }
  if (NULL != pos->filter)
  {
    GNUNET_CONTAINER_bloomfilter_free (pos->filter);
    pos->filter = NULL;
  }
  GNUNET_free (pos);
  return GNUNET_YES;
}


/**
 * Recalculate how much we want to be connected to the specified peer
 * and let ATS know about the result.
 *
 * @param pos peer to consider connecting to
 */
static void
attempt_connect (struct Peer *pos)
{
  uint32_t strength;

  if (0 == GNUNET_memcmp (&my_identity, &pos->pid))
    return; /* This is myself, nothing to do. */
  if (connection_count < target_connection_count)
    strength = 1;
  else
    strength = 0;
  if ((friend_count < minimum_friend_count) || (GNUNET_YES == friends_only))
  {
    if (pos->is_friend)
      strength += 10;   /* urgently needed */
    else
      strength = 0;   /* disallowed */
  }
  if (pos->is_friend)
    strength *= 2; /* friends always count more */
  if (NULL != pos->mq)
    strength *= 2; /* existing connections preferred */
  if (strength == pos->strength)
    return; /* nothing to do */
  if (NULL != pos->sh)
  {
    GNUNET_ATS_connectivity_suggest_cancel (pos->sh);
    pos->sh = NULL;
  }
  pos->strength = strength;
  if (0 != strength)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                "Asking to connect to `%s' with strength %u\n",
                GNUNET_i2s (&pos->pid),
                (unsigned int) strength);
    GNUNET_STATISTICS_update (stats,
                              gettext_noop ("# connect requests issued to ATS"),
                              1,
                              GNUNET_NO);
    pos->sh = GNUNET_ATS_connectivity_suggest (ats, &pos->pid, strength);
  }
}


/**
 * Create a new entry in the peer list.
 *
 * @param peer identity of the new entry
 * @param hello hello message, can be NULL
 * @param is_friend is the new entry for a friend?
 * @return the new entry
 */
static struct Peer *
make_peer (const struct GNUNET_PeerIdentity *peer,
           const struct GNUNET_HELLO_Message *hello,
           int is_friend)
{
  struct Peer *ret;

  ret = GNUNET_new (struct Peer);
  ret->pid = *peer;
  ret->is_friend = is_friend;
  if (NULL != hello)
  {
    ret->hello = GNUNET_malloc (GNUNET_HELLO_size (hello));
    GNUNET_memcpy (ret->hello, hello, GNUNET_HELLO_size (hello));
  }
  GNUNET_break (GNUNET_OK ==
                GNUNET_CONTAINER_multipeermap_put (
                  peers,
                  peer,
                  ret,
                  GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY));
  return ret;
}


/**
 * Setup bloom filter for the given peer entry.
 *
 * @param peer entry to initialize
 */
static void
setup_filter (struct Peer *peer)
{
  struct GNUNET_HashCode hc;

  /* 2^{-5} chance of not sending a HELLO to a peer is
   * acceptably small (if the filter is 50% full);
   * 64 bytes of memory are small compared to the rest
   * of the data structure and would only really become
   * "useless" once a HELLO has been passed on to ~100
   * other peers, which is likely more than enough in
   * any case; hence 64, 5 as bloomfilter parameters. */peer->filter = GNUNET_CONTAINER_bloomfilter_init (NULL, 64, 5);
  peer->filter_expiration =
    GNUNET_TIME_relative_to_absolute (HELLO_ADVERTISEMENT_MIN_REPEAT_FREQUENCY);
  /* never send a peer its own HELLO */
  GNUNET_CRYPTO_hash (&peer->pid, sizeof(struct GNUNET_PeerIdentity), &hc);
  GNUNET_CONTAINER_bloomfilter_add (peer->filter, &hc);
}


/**
 * Closure for #find_advertisable_hello().
 */
struct FindAdvHelloContext
{
  /**
   * Peer we want to advertise to.
   */
  struct Peer *peer;

  /**
   * Where to store the result (peer selected for advertising).
   */
  struct Peer *result;

  /**
   * Maximum HELLO size we can use right now.
   */
  size_t max_size;

  struct GNUNET_TIME_Relative next_adv;
};


/**
 * Find a peer that would be reasonable for advertising.
 *
 * @param cls closure
 * @param pid identity of a peer
 * @param value 'struct Peer*' for the peer we are considering
 * @return #GNUNET_YES (continue iteration)
 */
static int
find_advertisable_hello (void *cls,
                         const struct GNUNET_PeerIdentity *pid,
                         void *value)
{
  struct FindAdvHelloContext *fah = cls;
  struct Peer *pos = value;
  struct GNUNET_TIME_Relative rst_time;
  struct GNUNET_HashCode hc;
  size_t hs;

  if (pos == fah->peer)
    return GNUNET_YES;
  if (pos->hello == NULL)
    return GNUNET_YES;
  rst_time = GNUNET_TIME_absolute_get_remaining (pos->filter_expiration);
  if (0 == rst_time.rel_value_us)
  {
    /* time to discard... */
    GNUNET_CONTAINER_bloomfilter_free (pos->filter);
    setup_filter (pos);
  }
  fah->next_adv = GNUNET_TIME_relative_min (rst_time, fah->next_adv);
  hs = GNUNET_HELLO_size (pos->hello);
  if (hs > fah->max_size)
    return GNUNET_YES;
  GNUNET_CRYPTO_hash (&fah->peer->pid,
                      sizeof(struct GNUNET_PeerIdentity),
                      &hc);
  if (GNUNET_NO == GNUNET_CONTAINER_bloomfilter_test (pos->filter, &hc))
    fah->result = pos;
  return GNUNET_YES;
}


/**
 * Calculate when we would like to send the next HELLO to this
 * peer and ask for it.
 *
 * @param cls for which peer to schedule the HELLO
 */
static void
schedule_next_hello (void *cls)
{
  struct Peer *pl = cls;
  struct FindAdvHelloContext fah;
  struct GNUNET_MQ_Envelope *env;
  size_t want;
  struct GNUNET_TIME_Relative delay;
  struct GNUNET_HashCode hc;

  pl->hello_delay_task = NULL;
  GNUNET_assert (NULL != pl->mq);
  /* find applicable HELLOs */
  fah.peer = pl;
  fah.result = NULL;
  fah.max_size = GNUNET_MAX_MESSAGE_SIZE - 1;
  fah.next_adv = GNUNET_TIME_UNIT_FOREVER_REL;
  GNUNET_CONTAINER_multipeermap_iterate (peers, &find_advertisable_hello, &fah);
  pl->hello_delay_task =
    GNUNET_SCHEDULER_add_delayed (fah.next_adv, &schedule_next_hello, pl);
  if (NULL == fah.result)
    return;
  delay = GNUNET_TIME_absolute_get_remaining (pl->next_hello_allowed);
  if (0 != delay.rel_value_us)
    return;

  want = GNUNET_HELLO_size (fah.result->hello);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Sending HELLO with %u bytes",
              (unsigned int) want);
  env = GNUNET_MQ_msg_copy (&fah.result->hello->header);
  GNUNET_MQ_send (pl->mq, env);

  /* avoid sending this one again soon */
  GNUNET_CRYPTO_hash (&pl->pid, sizeof(struct GNUNET_PeerIdentity), &hc);
  GNUNET_CONTAINER_bloomfilter_add (fah.result->filter, &hc);

  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# HELLO messages gossipped"),
                            1,
                            GNUNET_NO);
  /* prepare to send the next one */
  pl->next_hello_allowed =
    GNUNET_TIME_relative_to_absolute (HELLO_ADVERTISEMENT_MIN_FREQUENCY);
  if (NULL != pl->hello_delay_task)
    GNUNET_SCHEDULER_cancel (pl->hello_delay_task);
  pl->hello_delay_task = GNUNET_SCHEDULER_add_now (&schedule_next_hello, pl);
}


/**
 * Cancel existing requests for sending HELLOs to this peer
 * and recalculate when we should send HELLOs to it based
 * on our current state (something changed!).
 *
 * @param cls closure `struct Peer` to skip, or NULL
 * @param pid identity of a peer
 * @param value `struct Peer *` for the peer
 * @return #GNUNET_YES (always)
 */
static int
reschedule_hellos (void *cls,
                   const struct GNUNET_PeerIdentity *pid,
                   void *value)
{
  struct Peer *peer = value;
  struct Peer *skip = cls;

  if (skip == peer)
    return GNUNET_YES;
  if (NULL == peer->mq)
    return GNUNET_YES;
  if (NULL != peer->hello_delay_task)
  {
    GNUNET_SCHEDULER_cancel (peer->hello_delay_task);
    peer->hello_delay_task = NULL;
  }
  peer->hello_delay_task =
    GNUNET_SCHEDULER_add_now (&schedule_next_hello, peer);
  return GNUNET_YES;
}


/**
 * Method called whenever a peer connects.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 * @param mq message queue for communicating with @a peer
 * @return our `struct Peer` for @a peer
 */
static void *
connect_notify (void *cls,
                const struct GNUNET_PeerIdentity *peer,
                struct GNUNET_MQ_Handle *mq)
{
  struct Peer *pos;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core told us that we are connecting to `%s'\n",
              GNUNET_i2s (peer));
  if (0 == GNUNET_memcmp (&my_identity, peer))
    return NULL;
  GNUNET_MQ_set_options (mq, GNUNET_MQ_PRIO_BEST_EFFORT);
  connection_count++;
  GNUNET_STATISTICS_set (stats,
                         gettext_noop ("# peers connected"),
                         connection_count,
                         GNUNET_NO);
  pos = GNUNET_CONTAINER_multipeermap_get (peers, peer);
  if (NULL == pos)
  {
    pos = make_peer (peer, NULL, GNUNET_NO);
  }
  else
  {
    GNUNET_assert (NULL == pos->mq);
  }
  pos->mq = mq;
  if (pos->is_friend)
  {
    friend_count++;
    if ((friend_count == minimum_friend_count) && (GNUNET_YES != friends_only))
      whitelist_peers ();
    GNUNET_STATISTICS_set (stats,
                           gettext_noop ("# friends connected"),
                           friend_count,
                           GNUNET_NO);
  }
  reschedule_hellos (NULL, peer, pos);
  return pos;
}


/**
 * Try to add more peers to our connection set.
 *
 * @param cls closure, not used
 * @param pid identity of a peer
 * @param value `struct Peer *` for the peer
 * @return #GNUNET_YES (continue to iterate)
 */
static int
try_add_peers (void *cls, const struct GNUNET_PeerIdentity *pid, void *value)
{
  struct Peer *pos = value;

  attempt_connect (pos);
  return GNUNET_YES;
}


/**
 * Add peers and schedule connection attempt
 *
 * @param cls unused, NULL
 */
static void
add_peer_task (void *cls)
{
  add_task = NULL;

  GNUNET_CONTAINER_multipeermap_iterate (peers, &try_add_peers, NULL);
}


/**
 * Method called whenever a peer disconnects.
 *
 * @param cls closure
 * @param peer peer identity this notification is about
 * @param internal_cls the `struct Peer` for this peer
 */
static void
disconnect_notify (void *cls,
                   const struct GNUNET_PeerIdentity *peer,
                   void *internal_cls)
{
  struct Peer *pos = internal_cls;

  if (NULL == pos)
    return; /* myself, we're shutting down */
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Core told us that we disconnected from `%s'\n",
              GNUNET_i2s (peer));
  if (NULL == pos->mq)
  {
    GNUNET_break (0);
    return;
  }
  pos->mq = NULL;
  connection_count--;
  if (NULL != pos->hello_delay_task)
  {
    GNUNET_SCHEDULER_cancel (pos->hello_delay_task);
    pos->hello_delay_task = NULL;
  }
  GNUNET_STATISTICS_set (stats,
                         gettext_noop ("# peers connected"),
                         connection_count,
                         GNUNET_NO);
  if (pos->is_friend)
  {
    friend_count--;
    GNUNET_STATISTICS_set (stats,
                           gettext_noop ("# friends connected"),
                           friend_count,
                           GNUNET_NO);
  }
  if (((connection_count < target_connection_count) ||
       (friend_count < minimum_friend_count)) &&
      (NULL == add_task))
    add_task = GNUNET_SCHEDULER_add_now (&add_peer_task, NULL);
  if ((friend_count < minimum_friend_count) && (NULL == blacklist))
    blacklist = GNUNET_TRANSPORT_blacklist (cfg, &blacklist_check, NULL);
}


/**
 * Iterator called on each address.
 *
 * @param cls flag that we will set if we see any addresses
 * @param address the address of the peer
 * @param expiration when will the given address expire
 * @return #GNUNET_SYSERR always, to terminate iteration
 */
static int
address_iterator (void *cls,
                  const struct GNUNET_HELLO_Address *address,
                  struct GNUNET_TIME_Absolute expiration)
{
  int *flag = cls;

  *flag = GNUNET_YES;
  return GNUNET_SYSERR;
}


/**
 * We've gotten a HELLO from another peer.  Consider it for
 * advertising.
 *
 * @param hello the HELLO we got
 */
static void
consider_for_advertising (const struct GNUNET_HELLO_Message *hello)
{
  int have_address;
  struct GNUNET_PeerIdentity pid;
  struct GNUNET_TIME_Absolute dt;
  struct GNUNET_HELLO_Message *nh;
  struct Peer *peer;
  uint16_t size;

  if (GNUNET_OK != GNUNET_HELLO_get_id (hello, &pid))
  {
    GNUNET_break (0);
    return;
  }
  if (0 == GNUNET_memcmp (&pid, &my_identity))
    return; /* that's me! */
  have_address = GNUNET_NO;
  GNUNET_HELLO_iterate_addresses (hello,
                                  GNUNET_NO,
                                  &address_iterator,
                                  &have_address);
  if (GNUNET_NO == have_address)
    return; /* no point in advertising this one... */
  peer = GNUNET_CONTAINER_multipeermap_get (peers, &pid);
  if (NULL == peer)
  {
    peer = make_peer (&pid, hello, GNUNET_NO);
  }
  else if (NULL != peer->hello)
  {
    dt = GNUNET_HELLO_equals (peer->hello, hello, GNUNET_TIME_absolute_get ());
    if (dt.abs_value_us == GNUNET_TIME_UNIT_FOREVER_ABS.abs_value_us)
      return;   /* nothing new here */
  }
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Found HELLO from peer `%s' for advertising\n",
              GNUNET_i2s (&pid));
  if (NULL != peer->hello)
  {
    nh = GNUNET_HELLO_merge (peer->hello, hello);
    GNUNET_free (peer->hello);
    peer->hello = nh;
  }
  else
  {
    size = GNUNET_HELLO_size (hello);
    peer->hello = GNUNET_malloc (size);
    GNUNET_memcpy (peer->hello, hello, size);
  }
  if (NULL != peer->filter)
  {
    GNUNET_CONTAINER_bloomfilter_free (peer->filter);
    peer->filter = NULL;
  }
  setup_filter (peer);
  /* since we have a new HELLO to pick from, re-schedule all
   * HELLO requests that are not bound by the HELLO send rate! */
  GNUNET_CONTAINER_multipeermap_iterate (peers, &reschedule_hellos, peer);
}


/**
 * PEERINFO calls this function to let us know about a possible peer
 * that we might want to connect to.
 *
 * @param cls closure (not used)
 * @param peer potential peer to connect to
 * @param hello HELLO for this peer (or NULL)
 * @param err_msg NULL if successful, otherwise contains error message
 */
static void
process_peer (void *cls,
              const struct GNUNET_PeerIdentity *peer,
              const struct GNUNET_HELLO_Message *hello,
              const char *err_msg)
{
  struct Peer *pos;

  if (NULL != err_msg)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
                _ ("Error in communication with PEERINFO service: %s\n"),
                err_msg);
    GNUNET_PEERINFO_notify_cancel (peerinfo_notify);
    peerinfo_notify =
      GNUNET_PEERINFO_notify (cfg, GNUNET_NO, &process_peer, NULL);
    return;
  }
  GNUNET_assert (NULL != peer);
  if (0 == GNUNET_memcmp (&my_identity, peer))
    return; /* that's me! */
  if (NULL == hello)
  {
    /* free existing HELLO, if any */
    pos = GNUNET_CONTAINER_multipeermap_get (peers, peer);
    if (NULL != pos)
    {
      GNUNET_free_non_null (pos->hello);
      pos->hello = NULL;
      if (NULL != pos->filter)
      {
        GNUNET_CONTAINER_bloomfilter_free (pos->filter);
        pos->filter = NULL;
      }
      if ((NULL == pos->mq) && (GNUNET_NO == pos->is_friend))
        free_peer (NULL, &pos->pid, pos);
    }
    return;
  }
  consider_for_advertising (hello);
  pos = GNUNET_CONTAINER_multipeermap_get (peers, peer);
  if (NULL == pos)
    pos = make_peer (peer, hello, GNUNET_NO);
  attempt_connect (pos);
}


/**
 * Function called after #GNUNET_CORE_connect has succeeded
 * (or failed for good).
 *
 * @param cls closure
 * @param my_id ID of this peer, NULL if we failed
 */
static void
core_init (void *cls, const struct GNUNET_PeerIdentity *my_id)
{
  if (NULL == my_id)
  {
    GNUNET_log (
      GNUNET_ERROR_TYPE_ERROR,
      _ ("Failed to connect to core service, can not manage topology!\n"));
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
  my_identity = *my_id;
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "I am peer `%s'\n", GNUNET_i2s (my_id));
  peerinfo_notify =
    GNUNET_PEERINFO_notify (cfg, GNUNET_NO, &process_peer, NULL);
}


/**
 * Process friend found in FRIENDS file.
 *
 * @param cls pointer to an `unsigned int` to be incremented per friend found
 * @param pid identity of the friend
 */
static void
handle_friend (void *cls, const struct GNUNET_PeerIdentity *pid)
{
  unsigned int *entries_found = cls;
  struct Peer *fl;

  if (0 == GNUNET_memcmp (pid, &my_identity))
  {
    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                _ ("Found myself `%s' in friend list (useless, ignored)\n"),
                GNUNET_i2s (pid));
    return;
  }
  (*entries_found)++;
  fl = make_peer (pid, NULL, GNUNET_YES);
  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
              _ ("Found friend `%s' in configuration\n"),
              GNUNET_i2s (&fl->pid));
}


/**
 * Read the friends file.
 */
static void
read_friends_file (const struct GNUNET_CONFIGURATION_Handle *cfg)
{
  unsigned int entries_found;

  entries_found = 0;
  if (GNUNET_OK != GNUNET_FRIENDS_parse (cfg, &handle_friend, &entries_found))
  {
    if ((GNUNET_YES == friends_only) || (minimum_friend_count > 0))
      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                  _ ("Encountered errors parsing friends list!\n"));
  }
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# friends in configuration"),
                            entries_found,
                            GNUNET_NO);
  if ((minimum_friend_count > entries_found) && (GNUNET_NO == friends_only))
  {
    GNUNET_log (
      GNUNET_ERROR_TYPE_WARNING,
      _ (
        "Fewer friends specified than required by minimum friend count. Will only connect to friends.\n"));
  }
  if ((minimum_friend_count > target_connection_count) &&
      (GNUNET_NO == friends_only))
  {
    GNUNET_log (
      GNUNET_ERROR_TYPE_WARNING,
      _ (
        "More friendly connections required than target total number of connections.\n"));
  }
}


/**
 * This function is called whenever an encrypted HELLO message is
 * received.
 *
 * @param cls closure with the peer identity of the sender
 * @param message the actual HELLO message
 * @return #GNUNET_OK if @a message is well-formed
 *         #GNUNET_SYSERR if @a message is invalid
 */
static int
check_hello (void *cls, const struct GNUNET_HELLO_Message *message)
{
  struct GNUNET_PeerIdentity pid;

  if (GNUNET_OK != GNUNET_HELLO_get_id (message, &pid))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * This function is called whenever an encrypted HELLO message is
 * received.
 *
 * @param cls closure with the peer identity of the sender
 * @param message the actual HELLO message
 */
static void
handle_hello (void *cls, const struct GNUNET_HELLO_Message *message)
{
  const struct GNUNET_PeerIdentity *other = cls;
  struct Peer *peer;
  struct GNUNET_PeerIdentity pid;

  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Received encrypted HELLO from peer `%s'",
              GNUNET_i2s (other));
  GNUNET_assert (GNUNET_OK == GNUNET_HELLO_get_id (message, &pid));
  GNUNET_STATISTICS_update (stats,
                            gettext_noop ("# HELLO messages received"),
                            1,
                            GNUNET_NO);
  peer = GNUNET_CONTAINER_multipeermap_get (peers, &pid);
  if (NULL == peer)
  {
    if ((GNUNET_YES == friends_only) || (friend_count < minimum_friend_count))
      return;
  }
  else
  {
    if ((GNUNET_YES != peer->is_friend) && (GNUNET_YES == friends_only))
      return;
    if ((GNUNET_YES != peer->is_friend) &&
        (friend_count < minimum_friend_count))
      return;
  }
  (void) GNUNET_PEERINFO_add_peer (pi, message, NULL, NULL);
}


/**
 * Last task run during shutdown.  Disconnects us from
 * the transport and core.
 *
 * @param cls unused, NULL
 */
static void
cleaning_task (void *cls)
{
  if (NULL != peerinfo_notify)
  {
    GNUNET_PEERINFO_notify_cancel (peerinfo_notify);
    peerinfo_notify = NULL;
  }
  if (NULL != handle)
  {
    GNUNET_CORE_disconnect (handle);
    handle = NULL;
  }
  whitelist_peers ();
  if (NULL != add_task)
  {
    GNUNET_SCHEDULER_cancel (add_task);
    add_task = NULL;
  }
  if (NULL != oh)
  {
    GNUNET_TRANSPORT_offer_hello_cancel (oh);
    oh = NULL;
  }
  GNUNET_CONTAINER_multipeermap_iterate (peers, &free_peer, NULL);
  GNUNET_CONTAINER_multipeermap_destroy (peers);
  peers = NULL;
  if (NULL != ats)
  {
    GNUNET_ATS_connectivity_done (ats);
    ats = NULL;
  }
  if (NULL != pi)
  {
    GNUNET_PEERINFO_disconnect (pi);
    pi = NULL;
  }
  if (NULL != stats)
  {
    GNUNET_STATISTICS_destroy (stats, GNUNET_NO);
    stats = NULL;
  }
}


/**
 * Main function that will be run.
 *
 * @param cls closure
 * @param args remaining command-line arguments
 * @param cfgfile name of the configuration file used (for saving, can be NULL!)
 * @param c configuration
 */
static void
run (void *cls,
     char *const *args,
     const char *cfgfile,
     const struct GNUNET_CONFIGURATION_Handle *c)
{
  struct GNUNET_MQ_MessageHandler handlers[] =
  { GNUNET_MQ_hd_var_size (hello,
                           GNUNET_MESSAGE_TYPE_HELLO,
                           struct GNUNET_HELLO_Message,
                           NULL),
    GNUNET_MQ_handler_end () };
  unsigned long long opt;

  cfg = c;
  stats = GNUNET_STATISTICS_create ("topology", cfg);
  friends_only =
    GNUNET_CONFIGURATION_get_value_yesno (cfg, "TOPOLOGY", "FRIENDS-ONLY");
  if (GNUNET_OK != GNUNET_CONFIGURATION_get_value_number (cfg,
                                                          "TOPOLOGY",
                                                          "MINIMUM-FRIENDS",
                                                          &opt))
    opt = 0;
  minimum_friend_count = (unsigned int) opt;
  if (GNUNET_OK !=
      GNUNET_CONFIGURATION_get_value_number (cfg,
                                             "TOPOLOGY",
                                             "TARGET-CONNECTION-COUNT",
                                             &opt))
    opt = 16;
  target_connection_count = (unsigned int) opt;
  peers = GNUNET_CONTAINER_multipeermap_create (target_connection_count * 2,
                                                GNUNET_NO);
  read_friends_file (cfg);
  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
              "Topology would like %u connections with at least %u friends\n",
              target_connection_count,
              minimum_friend_count);
  if ((GNUNET_YES == friends_only) || (minimum_friend_count > 0))
    blacklist = GNUNET_TRANSPORT_blacklist (cfg, &blacklist_check, NULL);
  ats = GNUNET_ATS_connectivity_init (cfg);
  pi = GNUNET_PEERINFO_connect (cfg);
  handle = GNUNET_CORE_connect (cfg,
                                NULL,
                                &core_init,
                                &connect_notify,
                                &disconnect_notify,
                                handlers);
  GNUNET_SCHEDULER_add_shutdown (&cleaning_task, NULL);
  if (NULL == handle)
  {
    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                _ ("Failed to connect to `%s' service.\n"),
                "core");
    GNUNET_SCHEDULER_shutdown ();
    return;
  }
}


/**
 * The main function for the topology daemon.
 *
 * @param argc number of arguments from the command line
 * @param argv command line arguments
 * @return 0 ok, 1 on error
 */
int
main (int argc, char *const *argv)
{
  static const struct GNUNET_GETOPT_CommandLineOption options[] = {
    GNUNET_GETOPT_OPTION_END
  };
  int ret;

  if (GNUNET_OK != GNUNET_STRINGS_get_utf8_args (argc, argv, &argc, &argv))
    return 2;

  ret = (GNUNET_OK == GNUNET_PROGRAM_run (argc,
                                          argv,
                                          "gnunet-daemon-topology",
                                          _ ("GNUnet topology control"),
                                          options,
                                          &run,
                                          NULL))
        ? 0
        : 1;
  GNUNET_free ((void *) argv);
  return ret;
}


#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_ARM_memory_init ()
{
  mallopt (M_TRIM_THRESHOLD, 4 * 1024);
  mallopt (M_TOP_PAD, 1 * 1024);
  malloc_trim (0);
}


#endif

/* end of gnunet-daemon-topology.c */