summaryrefslogtreecommitdiff
path: root/toxcore/onion_client.c
blob: d6d078e11d023b01b14384b9edbebb58d1db276e (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
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
/*
* onion_client.c -- Implementation of the client part of docs/Prevent_Tracking.txt
*                   (The part that uses the onion stuff to connect to the friend)
*
*  Copyright (C) 2013 Tox project All Rights Reserved.
*
*  This file is part of Tox.
*
*  Tox is free software: you can redistribute it and/or modify
*  it under the terms of the GNU General Public License as published by
*  the Free Software Foundation, either version 3 of the License, or
*  (at your option) any later version.
*
*  Tox is distributed in the hope that it will be useful,
*  but WITHOUT ANY WARRANTY; without even the implied warranty of
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*  GNU General Public License for more details.
*
*  You should have received a copy of the GNU General Public License
*  along with Tox.  If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "onion_client.h"
#include "util.h"
#include "LAN_discovery.h"

/* defines for the array size and
   timeout for onion announce packets. */
#define ANNOUNCE_ARRAY_SIZE 256
#define ANNOUNCE_TIMEOUT 10

/* Add a node to the path_nodes bootstrap array.
 *
 * return -1 on failure
 * return 0 on success
 */
int onion_add_bs_path_node(Onion_Client *onion_c, IP_Port ip_port, const uint8_t *public_key)
{
    if (ip_port.ip.family != AF_INET && ip_port.ip.family != AF_INET6)
        return -1;

    unsigned int i;

    for (i = 0; i < MAX_PATH_NODES; ++i) {
        if (memcmp(public_key, onion_c->path_nodes_bs[i].public_key, crypto_box_PUBLICKEYBYTES) == 0)
            return -1;
    }

    onion_c->path_nodes_bs[onion_c->path_nodes_index_bs % MAX_PATH_NODES].ip_port = ip_port;
    memcpy(onion_c->path_nodes_bs[onion_c->path_nodes_index_bs % MAX_PATH_NODES].public_key, public_key,
           crypto_box_PUBLICKEYBYTES);

    uint16_t last = onion_c->path_nodes_index_bs;
    ++onion_c->path_nodes_index_bs;

    if (onion_c->path_nodes_index_bs < last)
        onion_c->path_nodes_index_bs = MAX_PATH_NODES + 1;

    return 0;
}

/* Add a node to the path_nodes array.
 *
 * return -1 on failure
 * return 0 on success
 */
static int onion_add_path_node(Onion_Client *onion_c, IP_Port ip_port, const uint8_t *public_key)
{
    if (ip_port.ip.family != AF_INET && ip_port.ip.family != AF_INET6)
        return -1;

    unsigned int i;

    for (i = 0; i < MAX_PATH_NODES; ++i) {
        if (memcmp(public_key, onion_c->path_nodes[i].public_key, crypto_box_PUBLICKEYBYTES) == 0)
            return -1;
    }

    onion_c->path_nodes[onion_c->path_nodes_index % MAX_PATH_NODES].ip_port = ip_port;
    memcpy(onion_c->path_nodes[onion_c->path_nodes_index % MAX_PATH_NODES].public_key, public_key,
           crypto_box_PUBLICKEYBYTES);

    uint16_t last = onion_c->path_nodes_index;
    ++onion_c->path_nodes_index;

    if (onion_c->path_nodes_index < last)
        onion_c->path_nodes_index = MAX_PATH_NODES + 1;

    return 0;
}

/* Put up to max_num nodes in nodes.
 *
 * return the number of nodes.
 */
uint16_t onion_backup_nodes(const Onion_Client *onion_c, Node_format *nodes, uint16_t max_num)
{
    unsigned int i;

    if (!max_num)
        return 0;

    unsigned int num_nodes = (onion_c->path_nodes_index < MAX_PATH_NODES) ? onion_c->path_nodes_index : MAX_PATH_NODES;

    if (num_nodes == 0)
        return 0;

    if (num_nodes < max_num)
        max_num = num_nodes;

    for (i = 0; i < max_num; ++i) {
        nodes[i] = onion_c->path_nodes[(onion_c->path_nodes_index - (1 + i)) % num_nodes];
    }

    return max_num;
}

/* Put up to max_num random nodes in nodes.
 *
 * return the number of nodes.
 */
static uint16_t random_nodes_path_onion(const Onion_Client *onion_c, Node_format *nodes, uint16_t max_num)
{
    unsigned int i;

    if (!max_num)
        return 0;

    unsigned int num_nodes = (onion_c->path_nodes_index < MAX_PATH_NODES) ? onion_c->path_nodes_index : MAX_PATH_NODES;

    //if (DHT_non_lan_connected(onion_c->dht)) {
    if (DHT_isconnected(onion_c->dht)) {
        if (num_nodes == 0)
            return 0;

        for (i = 0; i < max_num; ++i) {
            nodes[i] = onion_c->path_nodes[rand() % num_nodes];
        }
    } else {
        int random_tcp = get_random_tcp_con_number(onion_c->c);

        if (random_tcp == -1) {
            return 0;
        }

        if (num_nodes >= 2) {
            nodes[0].ip_port.ip.family = TCP_FAMILY;
            nodes[0].ip_port.ip.ip4.uint32 = random_tcp;

            for (i = 1; i < max_num; ++i) {
                nodes[i] = onion_c->path_nodes[rand() % num_nodes];
            }
        } else {
            unsigned int num_nodes_bs = (onion_c->path_nodes_index_bs < MAX_PATH_NODES) ? onion_c->path_nodes_index_bs :
                                        MAX_PATH_NODES;

            if (num_nodes_bs == 0)
                return 0;

            nodes[0].ip_port.ip.family = TCP_FAMILY;
            nodes[0].ip_port.ip.ip4.uint32 = random_tcp;

            for (i = 1; i < max_num; ++i) {
                nodes[i] = onion_c->path_nodes_bs[rand() % num_nodes_bs];
            }
        }
    }

    return max_num;
}

/*
 * return -1 if nodes are suitable for creating a new path.
 * return path number of already existing similar path if one already exists.
 */
static int is_path_used(const Onion_Client_Paths *onion_paths, const Node_format *nodes)
{
    unsigned int i;

    for (i = 0; i < NUMBER_ONION_PATHS; ++i) {
        if (is_timeout(onion_paths->last_path_success[i], ONION_PATH_TIMEOUT)) {
            continue;
        }

        if (is_timeout(onion_paths->path_creation_time[i], ONION_PATH_MAX_LIFETIME)) {
            continue;
        }

        if (ipport_equal(&onion_paths->paths[i].ip_port1, &nodes[ONION_PATH_LENGTH - 1].ip_port)) {
            return i;
        }
    }

    return -1;
}

/* is path timed out */
static _Bool path_timed_out(Onion_Client_Paths *onion_paths, uint32_t pathnum)
{
    pathnum = pathnum % NUMBER_ONION_PATHS;

    return ((onion_paths->last_path_success[pathnum] + ONION_PATH_TIMEOUT < onion_paths->last_path_used[pathnum]
             && onion_paths->last_path_used_times[pathnum] >= ONION_PATH_MAX_NO_RESPONSE_USES)
            || is_timeout(onion_paths->path_creation_time[pathnum], ONION_PATH_MAX_LIFETIME));
}

/* Create a new path or use an old suitable one (if pathnum is valid)
 * or a random one from onion_paths.
 *
 * return -1 on failure
 * return 0 on success
 *
 * TODO: Make this function better, it currently probably is vulnerable to some attacks that
 * could de anonimize us.
 */
static int random_path(const Onion_Client *onion_c, Onion_Client_Paths *onion_paths, uint32_t pathnum, Onion_Path *path)
{
    if (pathnum == UINT32_MAX) {
        pathnum = rand() % NUMBER_ONION_PATHS;
    } else {
        pathnum = pathnum % NUMBER_ONION_PATHS;
    }

    if (path_timed_out(onion_paths, pathnum)) {
        Node_format nodes[ONION_PATH_LENGTH];

        if (random_nodes_path_onion(onion_c, nodes, ONION_PATH_LENGTH) != ONION_PATH_LENGTH)
            return -1;

        int n = is_path_used(onion_paths, nodes);

        if (n == -1) {
            if (create_onion_path(onion_c->dht, &onion_paths->paths[pathnum], nodes) == -1)
                return -1;

            onion_paths->last_path_success[pathnum] = unix_time() + ONION_PATH_FIRST_TIMEOUT - ONION_PATH_TIMEOUT;
            onion_paths->path_creation_time[pathnum] = unix_time();
            onion_paths->last_path_used_times[pathnum] = ONION_PATH_MAX_NO_RESPONSE_USES / 2;

            uint32_t path_num = rand();
            path_num /= NUMBER_ONION_PATHS;
            path_num *= NUMBER_ONION_PATHS;
            path_num += pathnum;

            onion_paths->paths[pathnum].path_num = path_num;
        } else {
            pathnum = n;
        }
    }

    ++onion_paths->last_path_used_times[pathnum];
    onion_paths->last_path_used[pathnum] = unix_time();
    memcpy(path, &onion_paths->paths[pathnum], sizeof(Onion_Path));
    return 0;
}

/* Does path with path_num exist. */
static _Bool path_exists(Onion_Client_Paths *onion_paths, uint32_t path_num)
{
    if (path_timed_out(onion_paths, path_num))
        return 0;

    return onion_paths->paths[path_num % NUMBER_ONION_PATHS].path_num == path_num;
}

/* Set path timeouts, return the path number.
 *
 */
static uint32_t set_path_timeouts(Onion_Client *onion_c, uint32_t num, uint32_t path_num)
{
    if (num > onion_c->num_friends)
        return -1;

    Onion_Client_Paths *onion_paths;

    if (num == 0) {
        onion_paths = &onion_c->onion_paths_self;
    } else {
        onion_paths = &onion_c->onion_paths_friends;
    }

    if (onion_paths->paths[path_num % NUMBER_ONION_PATHS].path_num == path_num) {
        onion_paths->last_path_success[path_num % NUMBER_ONION_PATHS] = unix_time();
        onion_paths->last_path_used_times[path_num % NUMBER_ONION_PATHS] = 0;

        Node_format nodes[ONION_PATH_LENGTH];

        if (onion_path_to_nodes(nodes, ONION_PATH_LENGTH, &onion_paths->paths[path_num % NUMBER_ONION_PATHS]) == 0) {
            unsigned int i;

            for (i = 0; i < ONION_PATH_LENGTH; ++i) {
                onion_add_path_node(onion_c, nodes[i].ip_port, nodes[i].public_key);
            }
        }

        return path_num;
    }

    return ~0;
}

/* Function to send onion packet via TCP and UDP.
 *
 * return -1 on failure.
 * return 0 on success.
 */
static int send_onion_packet_tcp_udp(const Onion_Client *onion_c, const Onion_Path *path, IP_Port dest,
                                     const uint8_t *data, uint16_t length)
{
    if (path->ip_port1.ip.family == AF_INET || path->ip_port1.ip.family == AF_INET6) {
        uint8_t packet[ONION_MAX_PACKET_SIZE];
        int len = create_onion_packet(packet, sizeof(packet), path, dest, data, length);

        if (len == -1)
            return -1;

        if (sendpacket(onion_c->net, path->ip_port1, packet, len) != len)
            return -1;

        return 0;
    } else if (path->ip_port1.ip.family == TCP_FAMILY) {
        uint8_t packet[ONION_MAX_PACKET_SIZE];
        int len = create_onion_packet_tcp(packet, sizeof(packet), path, dest, data, length);

        if (len == -1)
            return -1;

        return send_tcp_onion_request(onion_c->c, path->ip_port1.ip.ip4.uint32, packet, len);
    } else {
        return -1;
    }
}

/* Creates a sendback for use in an announce request.
 *
 * num is 0 if we used our secret public key for the announce
 * num is 1 + friendnum if we use a temporary one.
 *
 * Public key is the key we will be sending it to.
 * ip_port is the ip_port of the node we will be sending
 * it to.
 *
 * sendback must be at least ONION_ANNOUNCE_SENDBACK_DATA_LENGTH big
 *
 * return -1 on failure
 * return 0 on success
 *
 */
static int new_sendback(Onion_Client *onion_c, uint32_t num, const uint8_t *public_key, IP_Port ip_port,
                        uint32_t path_num, uint64_t *sendback)
{
    uint8_t data[sizeof(uint32_t) + crypto_box_PUBLICKEYBYTES + sizeof(IP_Port) + sizeof(uint32_t)];
    memcpy(data, &num, sizeof(uint32_t));
    memcpy(data + sizeof(uint32_t), public_key, crypto_box_PUBLICKEYBYTES);
    memcpy(data + sizeof(uint32_t) + crypto_box_PUBLICKEYBYTES, &ip_port, sizeof(IP_Port));
    memcpy(data + sizeof(uint32_t) + crypto_box_PUBLICKEYBYTES + sizeof(IP_Port), &path_num, sizeof(uint32_t));
    *sendback = ping_array_add(&onion_c->announce_ping_array, data, sizeof(data));

    if (*sendback == 0)
        return -1;

    return 0;
}

/* Checks if the sendback is valid and returns the public key contained in it in ret_pubkey and the
 * ip contained in it in ret_ip_port
 *
 * sendback is the sendback ONION_ANNOUNCE_SENDBACK_DATA_LENGTH big
 * ret_pubkey must be at least crypto_box_PUBLICKEYBYTES big
 * ret_ip_port must be at least 1 big
 *
 * return ~0 on failure
 * return num (see new_sendback(...)) on success
 */
static uint32_t check_sendback(Onion_Client *onion_c, const uint8_t *sendback, uint8_t *ret_pubkey,
                               IP_Port *ret_ip_port, uint32_t *path_num)
{
    uint64_t sback;
    memcpy(&sback, sendback, sizeof(uint64_t));
    uint8_t data[sizeof(uint32_t) + crypto_box_PUBLICKEYBYTES + sizeof(IP_Port) + sizeof(uint32_t)];

    if (ping_array_check(data, sizeof(data), &onion_c->announce_ping_array, sback) != sizeof(data))
        return ~0;

    memcpy(ret_pubkey, data + sizeof(uint32_t), crypto_box_PUBLICKEYBYTES);
    memcpy(ret_ip_port, data + sizeof(uint32_t) + crypto_box_PUBLICKEYBYTES, sizeof(IP_Port));
    memcpy(path_num, data + sizeof(uint32_t) + crypto_box_PUBLICKEYBYTES + sizeof(IP_Port), sizeof(uint32_t));

    uint32_t num;
    memcpy(&num, data, sizeof(uint32_t));
    return num;
}

static int client_send_announce_request(Onion_Client *onion_c, uint32_t num, IP_Port dest, const uint8_t *dest_pubkey,
                                        const uint8_t *ping_id, uint32_t pathnum)
{
    if (num > onion_c->num_friends)
        return -1;

    uint64_t sendback;
    Onion_Path path;

    if (num == 0) {
        if (random_path(onion_c, &onion_c->onion_paths_self, pathnum, &path) == -1)
            return -1;
    } else {
        if (random_path(onion_c, &onion_c->onion_paths_friends, pathnum, &path) == -1)
            return -1;
    }

    if (new_sendback(onion_c, num, dest_pubkey, dest, path.path_num, &sendback) == -1)
        return -1;

    uint8_t zero_ping_id[ONION_PING_ID_SIZE] = {0};

    if (ping_id == NULL)
        ping_id = zero_ping_id;

    uint8_t request[ONION_ANNOUNCE_REQUEST_SIZE];
    int len;

    if (num == 0) {
        len = create_announce_request(request, sizeof(request), dest_pubkey, onion_c->c->self_public_key,
                                      onion_c->c->self_secret_key, ping_id, onion_c->c->self_public_key, onion_c->temp_public_key, sendback);

    } else {
        len = create_announce_request(request, sizeof(request), dest_pubkey, onion_c->friends_list[num - 1].temp_public_key,
                                      onion_c->friends_list[num - 1].temp_secret_key, ping_id, onion_c->friends_list[num - 1].real_public_key, zero_ping_id,
                                      sendback);
    }

    if (len == -1) {
        return -1;
    }

    return send_onion_packet_tcp_udp(onion_c, &path, dest, request, len);
}

static uint8_t cmp_public_key[crypto_box_PUBLICKEYBYTES];
static int cmp_entry(const void *a, const void *b)
{
    Onion_Node entry1, entry2;
    memcpy(&entry1, a, sizeof(Onion_Node));
    memcpy(&entry2, b, sizeof(Onion_Node));
    int t1 = is_timeout(entry1.timestamp, ONION_NODE_TIMEOUT);
    int t2 = is_timeout(entry2.timestamp, ONION_NODE_TIMEOUT);

    if (t1 && t2)
        return 0;

    if (t1)
        return -1;

    if (t2)
        return 1;

    int close = id_closest(cmp_public_key, entry1.public_key, entry2.public_key);

    if (close == 1)
        return 1;

    if (close == 2)
        return -1;

    return 0;
}

static int client_add_to_list(Onion_Client *onion_c, uint32_t num, const uint8_t *public_key, IP_Port ip_port,
                              uint8_t is_stored, const uint8_t *pingid_or_key, uint32_t path_num)
{
    if (num > onion_c->num_friends)
        return -1;

    Onion_Node *list_nodes = NULL;
    uint8_t *reference_id = NULL;
    unsigned int list_length;

    if (num == 0) {
        list_nodes = onion_c->clients_announce_list;
        reference_id = onion_c->c->self_public_key;
        list_length = MAX_ONION_CLIENTS_ANNOUNCE;

        if (is_stored == 1 && memcmp(pingid_or_key, onion_c->temp_public_key, crypto_box_PUBLICKEYBYTES) != 0) {
            is_stored = 0;
        }

    } else {
        if (is_stored >= 2)
            return -1;

        list_nodes = onion_c->friends_list[num - 1].clients_list;
        reference_id = onion_c->friends_list[num - 1].real_public_key;
        list_length = MAX_ONION_CLIENTS;
    }

    memcpy(cmp_public_key, reference_id, crypto_box_PUBLICKEYBYTES);
    qsort(list_nodes, list_length, sizeof(Onion_Node), cmp_entry);

    int index = -1, stored = 0;
    unsigned int i;

    if (is_timeout(list_nodes[0].timestamp, ONION_NODE_TIMEOUT)
            || id_closest(reference_id, list_nodes[0].public_key, public_key) == 2) {
        index = 0;
    }

    for (i = 0; i < list_length; ++i) {
        if (memcmp(list_nodes[i].public_key, public_key, crypto_box_PUBLICKEYBYTES) == 0) {
            index = i;
            stored = 1;
            break;
        }
    }

    if (index == -1)
        return 0;

    memcpy(list_nodes[index].public_key, public_key, crypto_box_PUBLICKEYBYTES);
    list_nodes[index].ip_port = ip_port;

    //TODO: remove this and find a better source of nodes to use for paths.
    onion_add_path_node(onion_c, ip_port, public_key);

    if (is_stored == 1) {
        memcpy(list_nodes[index].data_public_key, pingid_or_key, crypto_box_PUBLICKEYBYTES);
    } else {
        memcpy(list_nodes[index].ping_id, pingid_or_key, ONION_PING_ID_SIZE);
    }

    list_nodes[index].is_stored = is_stored;
    list_nodes[index].timestamp = unix_time();

    if (!stored)
        list_nodes[index].last_pinged = 0;

    list_nodes[index].path_used = set_path_timeouts(onion_c, num, path_num);
    return 0;
}

static int good_to_ping(Last_Pinged *last_pinged, uint8_t *last_pinged_index, const uint8_t *public_key)
{
    unsigned int i;

    for (i = 0; i < MAX_STORED_PINGED_NODES; ++i) {
        if (!is_timeout(last_pinged[i].timestamp, MIN_NODE_PING_TIME))
            if (memcmp(last_pinged[i].public_key, public_key, crypto_box_PUBLICKEYBYTES) == 0)
                return 0;
    }

    memcpy(last_pinged[*last_pinged_index % MAX_STORED_PINGED_NODES].public_key, public_key, crypto_box_PUBLICKEYBYTES);
    last_pinged[*last_pinged_index % MAX_STORED_PINGED_NODES].timestamp = unix_time();
    ++*last_pinged_index;
    return 1;
}

static int client_ping_nodes(Onion_Client *onion_c, uint32_t num, const Node_format *nodes, uint16_t num_nodes,
                             IP_Port source)
{
    if (num > onion_c->num_friends)
        return -1;

    if (num_nodes == 0)
        return 0;

    Onion_Node *list_nodes = NULL;
    uint8_t *reference_id = NULL;
    unsigned int list_length;

    Last_Pinged *last_pinged = NULL;
    uint8_t *last_pinged_index = NULL;

    if (num == 0) {
        list_nodes = onion_c->clients_announce_list;
        reference_id = onion_c->c->self_public_key;
        list_length = MAX_ONION_CLIENTS_ANNOUNCE;
        last_pinged = onion_c->last_pinged;
        last_pinged_index = &onion_c->last_pinged_index;
    } else {
        list_nodes = onion_c->friends_list[num - 1].clients_list;
        reference_id = onion_c->friends_list[num - 1].real_public_key;
        list_length = MAX_ONION_CLIENTS;
        last_pinged = onion_c->friends_list[num - 1].last_pinged;
        last_pinged_index = &onion_c->friends_list[num - 1].last_pinged_index;
    }

    unsigned int i, j;
    int lan_ips_accepted = (LAN_ip(source.ip) == 0);

    for (i = 0; i < num_nodes; ++i) {

        if (!lan_ips_accepted)
            if (LAN_ip(nodes[i].ip_port.ip) == 0)
                continue;

        if (is_timeout(list_nodes[0].timestamp, ONION_NODE_TIMEOUT)
                || id_closest(reference_id, list_nodes[0].public_key, nodes[i].public_key) == 2
                || is_timeout(list_nodes[1].timestamp, ONION_NODE_TIMEOUT)
                || id_closest(reference_id, list_nodes[1].public_key, nodes[i].public_key) == 2 ) {
            /* check if node is already in list. */
            for (j = 0; j < list_length; ++j) {
                if (memcmp(list_nodes[j].public_key, nodes[i].public_key, crypto_box_PUBLICKEYBYTES) == 0) {
                    break;
                }
            }

            if (j == list_length && good_to_ping(last_pinged, last_pinged_index, nodes[i].public_key)) {
                client_send_announce_request(onion_c, num, nodes[i].ip_port, nodes[i].public_key, NULL, ~0);
            }
        }
    }

    return 0;
}

static int handle_announce_response(void *object, IP_Port source, const uint8_t *packet, uint16_t length)
{
    Onion_Client *onion_c = object;

    if (length < ONION_ANNOUNCE_RESPONSE_MIN_SIZE || length > ONION_ANNOUNCE_RESPONSE_MAX_SIZE)
        return 1;

    uint16_t len_nodes = length - ONION_ANNOUNCE_RESPONSE_MIN_SIZE;

    uint8_t public_key[crypto_box_PUBLICKEYBYTES];
    IP_Port ip_port;
    uint32_t path_num;
    uint32_t num = check_sendback(onion_c, packet + 1, public_key, &ip_port, &path_num);

    if (num > onion_c->num_friends)
        return 1;

    uint8_t plain[1 + ONION_PING_ID_SIZE + len_nodes];
    int len = -1;

    if (num == 0) {
        len = decrypt_data(public_key, onion_c->c->self_secret_key, packet + 1 + ONION_ANNOUNCE_SENDBACK_DATA_LENGTH,
                           packet + 1 + ONION_ANNOUNCE_SENDBACK_DATA_LENGTH + crypto_box_NONCEBYTES,
                           length - (1 + ONION_ANNOUNCE_SENDBACK_DATA_LENGTH + crypto_box_NONCEBYTES), plain);
    } else {
        if (onion_c->friends_list[num - 1].status == 0)
            return 1;

        len = decrypt_data(public_key, onion_c->friends_list[num - 1].temp_secret_key,
                           packet + 1 + ONION_ANNOUNCE_SENDBACK_DATA_LENGTH,
                           packet + 1 + ONION_ANNOUNCE_SENDBACK_DATA_LENGTH + crypto_box_NONCEBYTES,
                           length - (1 + ONION_ANNOUNCE_SENDBACK_DATA_LENGTH + crypto_box_NONCEBYTES), plain);
    }

    if ((uint32_t)len != sizeof(plain))
        return 1;

    if (client_add_to_list(onion_c, num, public_key, ip_port, plain[0], plain + 1, path_num) == -1)
        return 1;

    if (len_nodes != 0) {
        Node_format nodes[MAX_SENT_NODES];
        int num_nodes = unpack_nodes(nodes, MAX_SENT_NODES, 0, plain + 1 + ONION_PING_ID_SIZE, len_nodes, 0);

        if (num_nodes <= 0)
            return 1;

        if (client_ping_nodes(onion_c, num, nodes, num_nodes, source) == -1)
            return 1;
    }

    //TODO: LAN vs non LAN ips?, if we are connected only to LAN, are we offline?
    onion_c->last_packet_recv = unix_time();
    return 0;
}

#define DATA_IN_RESPONSE_MIN_SIZE ONION_DATA_IN_RESPONSE_MIN_SIZE

static int handle_data_response(void *object, IP_Port source, const uint8_t *packet, uint16_t length)
{
    Onion_Client *onion_c = object;

    if (length <= (ONION_DATA_RESPONSE_MIN_SIZE + DATA_IN_RESPONSE_MIN_SIZE))
        return 1;

    if (length > MAX_DATA_REQUEST_SIZE)
        return 1;

    uint8_t temp_plain[length - ONION_DATA_RESPONSE_MIN_SIZE];
    int len = decrypt_data(packet + 1 + crypto_box_NONCEBYTES, onion_c->temp_secret_key, packet + 1,
                           packet + 1 + crypto_box_NONCEBYTES + crypto_box_PUBLICKEYBYTES,
                           length - (1 + crypto_box_NONCEBYTES + crypto_box_PUBLICKEYBYTES), temp_plain);

    if ((uint32_t)len != sizeof(temp_plain))
        return 1;

    uint8_t plain[sizeof(temp_plain) - DATA_IN_RESPONSE_MIN_SIZE];
    len = decrypt_data(temp_plain, onion_c->c->self_secret_key, packet + 1, temp_plain + crypto_box_PUBLICKEYBYTES,
                       sizeof(temp_plain) - crypto_box_PUBLICKEYBYTES, plain);

    if ((uint32_t)len != sizeof(plain))
        return 1;

    if (!onion_c->Onion_Data_Handlers[plain[0]].function)
        return 1;

    return onion_c->Onion_Data_Handlers[plain[0]].function(onion_c->Onion_Data_Handlers[plain[0]].object, temp_plain, plain,
            sizeof(plain));
}

#define DHTPK_DATA_MIN_LENGTH (1 + sizeof(uint64_t) + crypto_box_PUBLICKEYBYTES)
#define DHTPK_DATA_MAX_LENGTH (DHTPK_DATA_MIN_LENGTH + sizeof(Node_format)*MAX_SENT_NODES)
static int handle_dhtpk_announce(void *object, const uint8_t *source_pubkey, const uint8_t *data, uint16_t length)
{
    Onion_Client *onion_c = object;

    if (length < DHTPK_DATA_MIN_LENGTH)
        return 1;

    if (length > DHTPK_DATA_MAX_LENGTH)
        return 1;

    int friend_num = onion_friend_num(onion_c, source_pubkey);

    if (friend_num == -1)
        return 1;

    uint64_t no_replay;
    memcpy(&no_replay, data + 1, sizeof(uint64_t));
    net_to_host((uint8_t *) &no_replay, sizeof(no_replay));

    if (no_replay <= onion_c->friends_list[friend_num].last_noreplay)
        return 1;

    onion_c->friends_list[friend_num].last_noreplay = no_replay;

    if (onion_c->friends_list[friend_num].dht_pk_callback)
        onion_c->friends_list[friend_num].dht_pk_callback(onion_c->friends_list[friend_num].dht_pk_callback_object,
                onion_c->friends_list[friend_num].dht_pk_callback_number, data + 1 + sizeof(uint64_t));

    onion_set_friend_DHT_pubkey(onion_c, friend_num, data + 1 + sizeof(uint64_t));
    onion_c->friends_list[friend_num].last_seen = unix_time();

    uint16_t len_nodes = length - DHTPK_DATA_MIN_LENGTH;

    if (len_nodes != 0) {
        Node_format nodes[MAX_SENT_NODES];
        int num_nodes = unpack_nodes(nodes, MAX_SENT_NODES, 0, data + 1 + sizeof(uint64_t) + crypto_box_PUBLICKEYBYTES,
                                     len_nodes, 1);

        if (num_nodes <= 0)
            return 1;

        int i;

        for (i = 0; i < num_nodes; ++i) {
            uint8_t family = nodes[i].ip_port.ip.family;

            if (family == AF_INET || family == AF_INET6) {
                DHT_getnodes(onion_c->dht, &nodes[i].ip_port, nodes[i].public_key, onion_c->friends_list[friend_num].dht_public_key);
            } else if (family == TCP_INET || family == TCP_INET6) {
                if (onion_c->friends_list[friend_num].tcp_relay_node_callback) {
                    void *obj = onion_c->friends_list[friend_num].tcp_relay_node_callback_object;
                    uint32_t number = onion_c->friends_list[friend_num].tcp_relay_node_callback_number;
                    onion_c->friends_list[friend_num].tcp_relay_node_callback(obj, number, nodes[i].ip_port, nodes[i].public_key);
                }
            }
        }
    }

    return 0;
}

static int handle_tcp_onion(void *object, const uint8_t *data, uint16_t length)
{
    if (length == 0)
        return 1;

    IP_Port ip_port = {0};
    ip_port.ip.family = TCP_FAMILY;

    if (data[0] == NET_PACKET_ANNOUNCE_RESPONSE) {
        return handle_announce_response(object, ip_port, data, length);
    } else if (data[0] == NET_PACKET_ONION_DATA_RESPONSE) {
        return handle_data_response(object, ip_port, data, length);
    }

    return 1;
}

/* Send data of length length to friendnum.
 * This data will be received by the friend using the Onion_Data_Handlers callbacks.
 *
 * Even if this function succeeds, the friend might not receive any data.
 *
 * return the number of packets sent on success
 * return -1 on failure.
 */
int send_onion_data(Onion_Client *onion_c, int friend_num, const uint8_t *data, uint16_t length)
{
    if ((uint32_t)friend_num >= onion_c->num_friends)
        return -1;

    if (length + DATA_IN_RESPONSE_MIN_SIZE > MAX_DATA_REQUEST_SIZE)
        return -1;

    if (length == 0)
        return -1;

    unsigned int i, good_nodes[MAX_ONION_CLIENTS], num_good = 0, num_nodes = 0;
    Onion_Node *list_nodes = onion_c->friends_list[friend_num].clients_list;

    for (i = 0; i < MAX_ONION_CLIENTS; ++i) {
        if (is_timeout(list_nodes[i].timestamp, ONION_NODE_TIMEOUT))
            continue;

        ++num_nodes;

        if (list_nodes[i].is_stored) {
            good_nodes[num_good] = i;
            ++num_good;
        }
    }

    if (num_good < (num_nodes / 4) + 1)
        return -1;

    uint8_t nonce[crypto_box_NONCEBYTES];
    random_nonce(nonce);

    uint8_t packet[DATA_IN_RESPONSE_MIN_SIZE + length];
    memcpy(packet, onion_c->c->self_public_key, crypto_box_PUBLICKEYBYTES);
    int len = encrypt_data(onion_c->friends_list[friend_num].real_public_key, onion_c->c->self_secret_key, nonce, data,
                           length, packet + crypto_box_PUBLICKEYBYTES);

    if ((uint32_t)len + crypto_box_PUBLICKEYBYTES != sizeof(packet))
        return -1;

    unsigned int good = 0;

    for (i = 0; i < num_good; ++i) {
        Onion_Path path;

        if (random_path(onion_c, &onion_c->onion_paths_friends, ~0, &path) == -1)
            continue;

        uint8_t o_packet[ONION_MAX_PACKET_SIZE];
        len = create_data_request(o_packet, sizeof(o_packet), onion_c->friends_list[friend_num].real_public_key,
                                  list_nodes[good_nodes[i]].data_public_key, nonce, packet, sizeof(packet));

        if (len == -1)
            continue;

        if (send_onion_packet_tcp_udp(onion_c, &path, list_nodes[good_nodes[i]].ip_port, o_packet, len) == 0)
            ++good;
    }

    return good;
}

/* Try to send the dht public key via the DHT instead of onion
 *
 * Even if this function succeeds, the friend might not receive any data.
 *
 * return the number of packets sent on success
 * return -1 on failure.
 */
static int send_dht_dhtpk(const Onion_Client *onion_c, int friend_num, const uint8_t *data, uint16_t length)
{
    if ((uint32_t)friend_num >= onion_c->num_friends)
        return -1;

    if (!onion_c->friends_list[friend_num].know_dht_public_key)
        return -1;

    uint8_t nonce[crypto_box_NONCEBYTES];
    new_nonce(nonce);

    uint8_t temp[DATA_IN_RESPONSE_MIN_SIZE + crypto_box_NONCEBYTES + length];
    memcpy(temp, onion_c->c->self_public_key, crypto_box_PUBLICKEYBYTES);
    memcpy(temp + crypto_box_PUBLICKEYBYTES, nonce, crypto_box_NONCEBYTES);
    int len = encrypt_data(onion_c->friends_list[friend_num].real_public_key, onion_c->c->self_secret_key, nonce, data,
                           length, temp + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES);

    if ((uint32_t)len + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES != sizeof(temp))
        return -1;

    uint8_t packet[MAX_CRYPTO_REQUEST_SIZE];
    len = create_request(onion_c->dht->self_public_key, onion_c->dht->self_secret_key, packet,
                         onion_c->friends_list[friend_num].dht_public_key, temp, sizeof(temp), CRYPTO_PACKET_DHTPK);

    if (len == -1)
        return -1;

    return route_tofriend(onion_c->dht, onion_c->friends_list[friend_num].dht_public_key, packet, len);
}

static int handle_dht_dhtpk(void *object, IP_Port source, const uint8_t *source_pubkey, const uint8_t *packet,
                            uint16_t length)
{
    Onion_Client *onion_c = object;

    if (length < DHTPK_DATA_MIN_LENGTH + DATA_IN_RESPONSE_MIN_SIZE + crypto_box_NONCEBYTES)
        return 1;

    if (length > DHTPK_DATA_MAX_LENGTH + DATA_IN_RESPONSE_MIN_SIZE + crypto_box_NONCEBYTES)
        return 1;

    uint8_t plain[DHTPK_DATA_MAX_LENGTH];
    int len = decrypt_data(packet, onion_c->c->self_secret_key, packet + crypto_box_PUBLICKEYBYTES,
                           packet + crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES,
                           length - (crypto_box_PUBLICKEYBYTES + crypto_box_NONCEBYTES), plain);

    if (len != length - (DATA_IN_RESPONSE_MIN_SIZE + crypto_box_NONCEBYTES))
        return 1;

    if (memcmp(source_pubkey, plain + 1 + sizeof(uint64_t), crypto_box_PUBLICKEYBYTES) != 0)
        return 1;

    return handle_dhtpk_announce(onion_c, packet, plain, len);
}
/* Send the packets to tell our friends what our DHT public key is.
 *
 * if onion_dht_both is 0, use only the onion to send the packet.
 * if it is 1, use only the dht.
 * if it is something else, use both.
 *
 * return the number of packets sent on success
 * return -1 on failure.
 */
static int send_dhtpk_announce(Onion_Client *onion_c, uint16_t friend_num, uint8_t onion_dht_both)
{
    if (friend_num >= onion_c->num_friends)
        return -1;

    uint8_t data[DHTPK_DATA_MAX_LENGTH];
    data[0] = ONION_DATA_DHTPK;
    uint64_t no_replay = unix_time();
    host_to_net((uint8_t *)&no_replay, sizeof(no_replay));
    memcpy(data + 1, &no_replay, sizeof(no_replay));
    memcpy(data + 1 + sizeof(uint64_t), onion_c->dht->self_public_key, crypto_box_PUBLICKEYBYTES);
    Node_format nodes[MAX_SENT_NODES];
    uint16_t num_relays = copy_connected_tcp_relays(onion_c->c, nodes, (MAX_SENT_NODES / 2));
    uint16_t num_nodes = closelist_nodes(onion_c->dht, &nodes[num_relays], MAX_SENT_NODES - num_relays);
    num_nodes += num_relays;
    int nodes_len = 0;

    if (num_nodes != 0) {
        nodes_len = pack_nodes(data + DHTPK_DATA_MIN_LENGTH, DHTPK_DATA_MAX_LENGTH - DHTPK_DATA_MIN_LENGTH, nodes,
                               num_nodes);

        if (nodes_len <= 0)
            return -1;
    }

    int num1 = -1, num2 = -1;

    if (onion_dht_both != 1)
        num1 = send_onion_data(onion_c, friend_num, data, DHTPK_DATA_MIN_LENGTH + nodes_len);

    if (onion_dht_both != 0)
        num2 = send_dht_dhtpk(onion_c, friend_num, data, DHTPK_DATA_MIN_LENGTH + nodes_len);

    if (num1 == -1)
        return num2;

    if (num2 == -1)
        return num1;

    return num1 + num2;
}

/* Get the friend_num of a friend.
 *
 * return -1 on failure.
 * return friend number on success.
 */
int onion_friend_num(const Onion_Client *onion_c, const uint8_t *public_key)
{
    unsigned int i;

    for (i = 0; i < onion_c->num_friends; ++i) {
        if (onion_c->friends_list[i].status == 0)
            continue;

        if (memcmp(public_key, onion_c->friends_list[i].real_public_key, crypto_box_PUBLICKEYBYTES) == 0)
            return i;
    }

    return -1;
}

/* Set the size of the friend list to num.
 *
 *  return -1 if realloc fails.
 *  return 0 if it succeeds.
 */
static int realloc_onion_friends(Onion_Client *onion_c, uint32_t num)
{
    if (num == 0) {
        free(onion_c->friends_list);
        onion_c->friends_list = NULL;
        return 0;
    }

    Onion_Friend *newonion_friends = realloc(onion_c->friends_list, num * sizeof(Onion_Friend));

    if (newonion_friends == NULL)
        return -1;

    onion_c->friends_list = newonion_friends;
    return 0;
}

/* Add a friend who we want to connect to.
 *
 * return -1 on failure.
 * return the friend number on success or if the friend was already added.
 */
int onion_addfriend(Onion_Client *onion_c, const uint8_t *public_key)
{
    int num = onion_friend_num(onion_c, public_key);

    if (num != -1)
        return num;

    unsigned int i, index = ~0;

    for (i = 0; i < onion_c->num_friends; ++i) {
        if (onion_c->friends_list[i].status == 0) {
            index = i;
            break;
        }
    }

    if (index == (uint32_t)~0) {
        if (realloc_onion_friends(onion_c, onion_c->num_friends + 1) == -1)
            return -1;

        index = onion_c->num_friends;
        memset(&(onion_c->friends_list[onion_c->num_friends]), 0, sizeof(Onion_Friend));
        ++onion_c->num_friends;
    }

    onion_c->friends_list[index].status = 1;
    memcpy(onion_c->friends_list[index].real_public_key, public_key, crypto_box_PUBLICKEYBYTES);
    crypto_box_keypair(onion_c->friends_list[index].temp_public_key, onion_c->friends_list[index].temp_secret_key);
    return index;
}

/* Delete a friend.
 *
 * return -1 on failure.
 * return the deleted friend number on success.
 */
int onion_delfriend(Onion_Client *onion_c, int friend_num)
{
    if ((uint32_t)friend_num >= onion_c->num_friends)
        return -1;

    //if (onion_c->friends_list[friend_num].know_dht_public_key)
    //    DHT_delfriend(onion_c->dht, onion_c->friends_list[friend_num].dht_public_key, 0);

    memset(&(onion_c->friends_list[friend_num]), 0, sizeof(Onion_Friend));
    unsigned int i;

    for (i = onion_c->num_friends; i != 0; --i) {
        if (onion_c->friends_list[i - 1].status != 0)
            break;
    }

    if (onion_c->num_friends != i) {
        onion_c->num_friends = i;
        realloc_onion_friends(onion_c, onion_c->num_friends);
    }

    return friend_num;
}

/* Set the function for this friend that will be callbacked with object and number
 * when that friends gives us one of the TCP relays he is connected to.
 *
 * object and number will be passed as argument to this function.
 *
 * return -1 on failure.
 * return 0 on success.
 */
int recv_tcp_relay_handler(Onion_Client *onion_c, int friend_num, int (*tcp_relay_node_callback)(void *object,
                           uint32_t number, IP_Port ip_port, const uint8_t *public_key), void *object, uint32_t number)
{
    if ((uint32_t)friend_num >= onion_c->num_friends)
        return -1;

    onion_c->friends_list[friend_num].tcp_relay_node_callback = tcp_relay_node_callback;
    onion_c->friends_list[friend_num].tcp_relay_node_callback_object = object;
    onion_c->friends_list[friend_num].tcp_relay_node_callback_number = number;
    return 0;
}

/* Set the function for this friend that will be callbacked with object and number
 * when that friend gives us his DHT temporary public key.
 *
 * object and number will be passed as argument to this function.
 *
 * return -1 on failure.
 * return 0 on success.
 */
int onion_dht_pk_callback(Onion_Client *onion_c, int friend_num, void (*function)(void *data, int32_t number,
                          const uint8_t *dht_public_key), void *object, uint32_t number)
{
    if ((uint32_t)friend_num >= onion_c->num_friends)
        return -1;

    onion_c->friends_list[friend_num].dht_pk_callback = function;
    onion_c->friends_list[friend_num].dht_pk_callback_object = object;
    onion_c->friends_list[friend_num].dht_pk_callback_number = number;
    return 0;
}

/* Set a friends DHT public key.
 *
 * return -1 on failure.
 * return 0 on success.
 */
int onion_set_friend_DHT_pubkey(Onion_Client *onion_c, int friend_num, const uint8_t *dht_key)
{
    if ((uint32_t)friend_num >= onion_c->num_friends)
        return -1;

    if (onion_c->friends_list[friend_num].status == 0)
        return -1;

    if (onion_c->friends_list[friend_num].know_dht_public_key) {
        if (memcmp(dht_key, onion_c->friends_list[friend_num].dht_public_key, crypto_box_PUBLICKEYBYTES) == 0) {
            return -1;
        }

        onion_c->friends_list[friend_num].know_dht_public_key = 0;
    }

    onion_c->friends_list[friend_num].last_seen = unix_time();
    onion_c->friends_list[friend_num].know_dht_public_key = 1;
    memcpy(onion_c->friends_list[friend_num].dht_public_key, dht_key, crypto_box_PUBLICKEYBYTES);

    return 0;
}

/* Copy friends DHT public key into dht_key.
 *
 * return 0 on failure (no key copied).
 * return 1 on success (key copied).
 */
unsigned int onion_getfriend_DHT_pubkey(const Onion_Client *onion_c, int friend_num, uint8_t *dht_key)
{
    if ((uint32_t)friend_num >= onion_c->num_friends)
        return 0;

    if (onion_c->friends_list[friend_num].status == 0)
        return 0;

    if (!onion_c->friends_list[friend_num].know_dht_public_key)
        return 0;

    memcpy(dht_key, onion_c->friends_list[friend_num].dht_public_key, crypto_box_PUBLICKEYBYTES);
    return 1;
}

/* Get the ip of friend friendnum and put it in ip_port
 *
 *  return -1, -- if public_key does NOT refer to a friend
 *  return  0, -- if public_key refers to a friend and we failed to find the friend (yet)
 *  return  1, ip if public_key refers to a friend and we found him
 *
 */
int onion_getfriendip(const Onion_Client *onion_c, int friend_num, IP_Port *ip_port)
{
    uint8_t dht_public_key[crypto_box_PUBLICKEYBYTES];

    if (onion_getfriend_DHT_pubkey(onion_c, friend_num, dht_public_key) == 0)
        return -1;

    return DHT_getfriendip(onion_c->dht, dht_public_key, ip_port);
}


/* Set if friend is online or not.
 * NOTE: This function is there and should be used so that we don't send useless packets to the friend if he is online.
 *
 * is_online 1 means friend is online.
 * is_online 0 means friend is offline
 *
 * return -1 on failure.
 * return 0 on success.
 */
int onion_set_friend_online(Onion_Client *onion_c, int friend_num, uint8_t is_online)
{
    if ((uint32_t)friend_num >= onion_c->num_friends)
        return -1;

    if (is_online == 0 && onion_c->friends_list[friend_num].is_online == 1)
        onion_c->friends_list[friend_num].last_seen = unix_time();

    onion_c->friends_list[friend_num].is_online = is_online;

    /* This should prevent some clock related issues */
    if (!is_online) {
        onion_c->friends_list[friend_num].last_noreplay = 0;
        onion_c->friends_list[friend_num].run_count = 0;
    }

    return 0;
}

static void populate_path_nodes(Onion_Client *onion_c)
{
    Node_format nodes_list[MAX_FRIEND_CLIENTS];

    unsigned int num_nodes = randfriends_nodes(onion_c->dht, nodes_list, MAX_FRIEND_CLIENTS);

    unsigned int i;

    for (i = 0; i < num_nodes; ++i) {
        onion_add_path_node(onion_c, nodes_list[i].ip_port, nodes_list[i].public_key);
    }
}

static void populate_path_nodes_tcp(Onion_Client *onion_c)
{
    Node_format nodes_list[MAX_SENT_NODES];

    unsigned int num_nodes = copy_connected_tcp_relays(onion_c->c, nodes_list, MAX_SENT_NODES);;
    unsigned int i;

    for (i = 0; i < num_nodes; ++i) {
        onion_add_bs_path_node(onion_c, nodes_list[i].ip_port, nodes_list[i].public_key);
    }
}

#define ANNOUNCE_FRIEND (ONION_NODE_PING_INTERVAL * 6)
#define ANNOUNCE_FRIEND_BEGINNING 3
#define FRIEND_ONION_NODE_TIMEOUT (ONION_NODE_TIMEOUT * 6)

#define RUN_COUNT_FRIEND_ANNOUNCE_BEGINNING 17

static void do_friend(Onion_Client *onion_c, uint16_t friendnum)
{
    if (friendnum >= onion_c->num_friends)
        return;

    if (onion_c->friends_list[friendnum].status == 0)
        return;

    unsigned int interval = ANNOUNCE_FRIEND;

    if (onion_c->friends_list[friendnum].run_count < RUN_COUNT_FRIEND_ANNOUNCE_BEGINNING)
        interval = ANNOUNCE_FRIEND_BEGINNING;

    unsigned int i, count = 0;
    Onion_Node *list_nodes = onion_c->friends_list[friendnum].clients_list;

    if (!onion_c->friends_list[friendnum].is_online) {
        for (i = 0; i < MAX_ONION_CLIENTS; ++i) {
            if (is_timeout(list_nodes[i].timestamp, FRIEND_ONION_NODE_TIMEOUT))
                continue;

            ++count;


            if (list_nodes[i].last_pinged == 0) {
                list_nodes[i].last_pinged = unix_time();
                continue;
            }

            if (is_timeout(list_nodes[i].last_pinged, interval)) {
                if (client_send_announce_request(onion_c, friendnum + 1, list_nodes[i].ip_port, list_nodes[i].public_key, 0, ~0) == 0) {
                    list_nodes[i].last_pinged = unix_time();
                }
            }
        }

        if (count != MAX_ONION_CLIENTS) {
            unsigned int num_nodes = (onion_c->path_nodes_index < MAX_PATH_NODES) ? onion_c->path_nodes_index : MAX_PATH_NODES;

            unsigned int n = num_nodes;

            if (num_nodes > (MAX_ONION_CLIENTS / 2))
                n = (MAX_ONION_CLIENTS / 2);

            if (num_nodes != 0) {
                unsigned int j;

                for (j = 0; j < n; ++j) {
                    unsigned int num = rand() % num_nodes;
                    client_send_announce_request(onion_c, friendnum + 1, onion_c->path_nodes[num].ip_port,
                                                 onion_c->path_nodes[num].public_key, 0, ~0);
                }

                ++onion_c->friends_list[friendnum].run_count;
            }
        } else {
            ++onion_c->friends_list[friendnum].run_count;
        }

        /* send packets to friend telling them our DHT public key. */
        if (is_timeout(onion_c->friends_list[friendnum].last_dht_pk_onion_sent, ONION_DHTPK_SEND_INTERVAL))
            if (send_dhtpk_announce(onion_c, friendnum, 0) >= 1)
                onion_c->friends_list[friendnum].last_dht_pk_onion_sent = unix_time();

        if (is_timeout(onion_c->friends_list[friendnum].last_dht_pk_dht_sent, DHT_DHTPK_SEND_INTERVAL))
            if (send_dhtpk_announce(onion_c, friendnum, 1) >= 1)
                onion_c->friends_list[friendnum].last_dht_pk_dht_sent = unix_time();

    }
}


/* Function to call when onion data packet with contents beginning with byte is received. */
void oniondata_registerhandler(Onion_Client *onion_c, uint8_t byte, oniondata_handler_callback cb, void *object)
{
    onion_c->Onion_Data_Handlers[byte].function = cb;
    onion_c->Onion_Data_Handlers[byte].object = object;
}

#define ANNOUNCE_INTERVAL_NOT_ANNOUNCED 3
#define ANNOUNCE_INTERVAL_ANNOUNCED ONION_NODE_PING_INTERVAL

static void do_announce(Onion_Client *onion_c)
{
    unsigned int i, count = 0;
    Onion_Node *list_nodes = onion_c->clients_announce_list;

    for (i = 0; i < MAX_ONION_CLIENTS_ANNOUNCE; ++i) {
        if (is_timeout(list_nodes[i].timestamp, ONION_NODE_TIMEOUT))
            continue;

        ++count;

        /* Don't announce ourselves the first time this is run to new peers */
        if (list_nodes[i].last_pinged == 0) {
            list_nodes[i].last_pinged = 1;
            continue;
        }

        unsigned int interval = ANNOUNCE_INTERVAL_NOT_ANNOUNCED;

        if (list_nodes[i].is_stored && path_exists(&onion_c->onion_paths_self, list_nodes[i].path_used)) {
            interval = ANNOUNCE_INTERVAL_ANNOUNCED;
        }

        if (is_timeout(list_nodes[i].last_pinged, interval)) {
            if (client_send_announce_request(onion_c, 0, list_nodes[i].ip_port, list_nodes[i].public_key,
                                             list_nodes[i].ping_id, list_nodes[i].path_used) == 0) {
                list_nodes[i].last_pinged = unix_time();
            }
        }
    }

    if (count != MAX_ONION_CLIENTS_ANNOUNCE) {
        unsigned int num_nodes;
        Node_format *path_nodes;

        if (rand() % 2 == 0 || onion_c->path_nodes_index == 0) {
            num_nodes = (onion_c->path_nodes_index_bs < MAX_PATH_NODES) ? onion_c->path_nodes_index_bs : MAX_PATH_NODES;
            path_nodes = onion_c->path_nodes_bs;
        } else {
            num_nodes = (onion_c->path_nodes_index < MAX_PATH_NODES) ? onion_c->path_nodes_index : MAX_PATH_NODES;
            path_nodes = onion_c->path_nodes;
        }

        if (count < (uint32_t)rand() % MAX_ONION_CLIENTS_ANNOUNCE) {
            if (num_nodes != 0) {
                for (i = 0; i < (MAX_ONION_CLIENTS_ANNOUNCE / 2); ++i) {
                    unsigned int num = rand() % num_nodes;
                    client_send_announce_request(onion_c, 0, path_nodes[num].ip_port, path_nodes[num].public_key, 0, ~0);
                }
            }
        }
    }
}

/*  return 0 if we are not connected to the network.
 *  return 1 if we are.
 */
static int onion_isconnected(const Onion_Client *onion_c)
{
    unsigned int i, num = 0, announced = 0;

    if (is_timeout(onion_c->last_packet_recv, ONION_OFFLINE_TIMEOUT))
        return 0;

    if (onion_c->path_nodes_index == 0)
        return 0;

    for (i = 0; i < MAX_ONION_CLIENTS_ANNOUNCE; ++i) {
        if (!is_timeout(onion_c->clients_announce_list[i].timestamp, ONION_NODE_TIMEOUT)) {
            ++num;

            if (onion_c->clients_announce_list[i].is_stored) {
                ++announced;
            }
        }
    }

    unsigned int pnodes = onion_c->path_nodes_index;

    if (pnodes > MAX_ONION_CLIENTS_ANNOUNCE) {
        pnodes = MAX_ONION_CLIENTS_ANNOUNCE;
    }

    /* Consider ourselves online if we are announced to half or more nodes
      we are connected to */
    if (num && announced) {
        if ((num / 2) <= announced && (pnodes / 2) <= num)
            return 1;
    }

    return 0;
}

#define ONION_CONNECTION_SECONDS 3

/*  return 0 if we are not connected to the network.
 *  return 1 if we are connected with TCP only.
 *  return 2 if we are also connected with UDP.
 */
unsigned int onion_connection_status(const Onion_Client *onion_c)
{
    if (onion_c->onion_connected >= ONION_CONNECTION_SECONDS) {
        if (onion_c->UDP_connected) {
            return 2;
        } else {
            return 1;
        }
    }

    return 0;
}

void do_onion_client(Onion_Client *onion_c)
{
    unsigned int i;

    if (onion_c->last_run == unix_time())
        return;

    if (is_timeout(onion_c->first_run, ONION_CONNECTION_SECONDS)) {
        populate_path_nodes(onion_c);
        do_announce(onion_c);
    }

    if (onion_isconnected(onion_c)) {
        if (onion_c->onion_connected < ONION_CONNECTION_SECONDS * 2) {
            ++onion_c->onion_connected;
        }

    } else {
        populate_path_nodes_tcp(onion_c);

        if (onion_c->onion_connected != 0) {
            --onion_c->onion_connected;
        }
    }

    _Bool UDP_connected = DHT_non_lan_connected(onion_c->dht);

    if (is_timeout(onion_c->first_run, ONION_CONNECTION_SECONDS * 2)) {
        set_tcp_onion_status(onion_c->c->tcp_c, !UDP_connected);
    }

    onion_c->UDP_connected = UDP_connected
                             || get_random_tcp_onion_conn_number(onion_c->c->tcp_c) == -1; /* Check if connected to any TCP relays. */

    if (onion_connection_status(onion_c)) {
        for (i = 0; i < onion_c->num_friends; ++i) {
            do_friend(onion_c, i);
        }
    }

    if (onion_c->last_run == 0) {
        onion_c->first_run = unix_time();
    }

    onion_c->last_run = unix_time();
}

Onion_Client *new_onion_client(Net_Crypto *c)
{
    if (c == NULL)
        return NULL;

    Onion_Client *onion_c = calloc(1, sizeof(Onion_Client));

    if (onion_c == NULL)
        return NULL;

    if (ping_array_init(&onion_c->announce_ping_array, ANNOUNCE_ARRAY_SIZE, ANNOUNCE_TIMEOUT) != 0) {
        free(onion_c);
        return NULL;
    }

    onion_c->dht = c->dht;
    onion_c->net = c->dht->net;
    onion_c->c = c;
    new_symmetric_key(onion_c->secret_symmetric_key);
    crypto_box_keypair(onion_c->temp_public_key, onion_c->temp_secret_key);
    networking_registerhandler(onion_c->net, NET_PACKET_ANNOUNCE_RESPONSE, &handle_announce_response, onion_c);
    networking_registerhandler(onion_c->net, NET_PACKET_ONION_DATA_RESPONSE, &handle_data_response, onion_c);
    oniondata_registerhandler(onion_c, ONION_DATA_DHTPK, &handle_dhtpk_announce, onion_c);
    cryptopacket_registerhandler(onion_c->dht, CRYPTO_PACKET_DHTPK, &handle_dht_dhtpk, onion_c);
    set_onion_packet_tcp_connection_callback(onion_c->c->tcp_c, &handle_tcp_onion, onion_c);

    return onion_c;
}

void kill_onion_client(Onion_Client *onion_c)
{
    if (onion_c == NULL)
        return;

    ping_array_free_all(&onion_c->announce_ping_array);
    realloc_onion_friends(onion_c, 0);
    networking_registerhandler(onion_c->net, NET_PACKET_ANNOUNCE_RESPONSE, NULL, NULL);
    networking_registerhandler(onion_c->net, NET_PACKET_ONION_DATA_RESPONSE, NULL, NULL);
    oniondata_registerhandler(onion_c, ONION_DATA_DHTPK, NULL, NULL);
    cryptopacket_registerhandler(onion_c->dht, CRYPTO_PACKET_DHTPK, NULL, NULL);
    set_onion_packet_tcp_connection_callback(onion_c->c->tcp_c, NULL, NULL);
    memset(onion_c, 0, sizeof(Onion_Client));
    free(onion_c);
}