summaryrefslogtreecommitdiffstats
path: root/src/vnet/bfd/bfd_udp.c
blob: ec42cda1bc4dbfa29a88da7ceb4f7f9c5c44e6f7 (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
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
/*
 * Copyright (c) 2011-2016 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/**
 * @file
 * @brief BFD UDP transport layer implementation
 */
#include <vppinfra/types.h>
#include <vlibmemory/api.h>
#include <vlib/vlib.h>
#include <vlib/buffer.h>
#include <vnet/ip/format.h>
#include <vnet/ethernet/packet.h>
#include <vnet/udp/udp_local.h>
#include <vnet/udp/udp_packet.h>
#include <vnet/ip/lookup.h>
#include <vnet/ip/icmp46_packet.h>
#include <vnet/ip/ip4.h>
#include <vnet/ip/ip6.h>
#include <vnet/ip/ip6_packet.h>
#include <vnet/ip/ip6_link.h>
#include <vnet/adj/adj.h>
#include <vnet/adj/adj_nbr.h>
#include <vnet/dpo/receive_dpo.h>
#include <vnet/fib/fib_entry.h>
#include <vnet/fib/fib_table.h>
#include <vlib/stats/stats.h>
#include <vnet/bfd/bfd_debug.h>
#include <vnet/bfd/bfd_udp.h>
#include <vnet/bfd/bfd_main.h>
#include <vnet/bfd/bfd_api.h>
#include <vnet/bfd/bfd.api_enum.h>

#define F(sym, str)                                                           \
  STATIC_ASSERT ((int) BFD_ERROR_##sym == (int) BFD_UDP_ERROR_##sym,          \
		 "BFD error enums mismatch");
foreach_bfd_error (F)
#undef F
  STATIC_ASSERT ((int) BFD_N_ERROR <= (int) BFD_UDP_N_ERROR,
		 "BFD error enum sizes mismatch");

typedef struct
{
  bfd_main_t *bfd_main;
  /* hashmap - bfd session index by bfd key - used for CLI/API lookup, where
   * discriminator is unknown */
  mhash_t bfd_session_idx_by_bfd_key;
  /* convenience variable */
  vnet_main_t *vnet_main;
  /* flag indicating whether echo_source_sw_if_index holds a valid value */
  int echo_source_is_set;
  /* loopback interface used to get echo source ip */
  u32 echo_source_sw_if_index;
  /* log class */
  vlib_log_class_t log_class;
  /* number of active udp4 sessions */
  u32 udp4_sessions_count;
  u32 udp4_sessions_count_stat_seg_entry;
  /* number of active udp6 sessions */
  u32 udp6_sessions_count;
  u32 udp6_sessions_count_stat_seg_entry;
} bfd_udp_main_t;

static vlib_node_registration_t bfd_udp4_input_node;
static vlib_node_registration_t bfd_udp6_input_node;
static vlib_node_registration_t bfd_udp_echo4_input_node;
static vlib_node_registration_t bfd_udp_echo6_input_node;

bfd_udp_main_t bfd_udp_main;

void
bfd_udp_update_stat_segment_entry (u32 entry, u64 value)
{
  vlib_stats_segment_lock ();
  vlib_stats_set_gauge (entry, value);
  vlib_stats_segment_unlock ();
}

vnet_api_error_t
bfd_udp_set_echo_source (u32 sw_if_index)
{
  vnet_sw_interface_t *sw_if =
    vnet_get_sw_interface_or_null (bfd_udp_main.vnet_main, sw_if_index);
  if (sw_if)
    {
      bfd_udp_main.echo_source_sw_if_index = sw_if_index;
      bfd_udp_main.echo_source_is_set = 1;
      return 0;
    }
  return VNET_API_ERROR_BFD_ENOENT;
}

vnet_api_error_t
bfd_udp_del_echo_source ()
{
  bfd_udp_main.echo_source_sw_if_index = ~0;
  bfd_udp_main.echo_source_is_set = 0;
  return 0;
}

int
bfd_udp_is_echo_available (bfd_transport_e transport)
{
  if (!bfd_udp_main.echo_source_is_set)
    {
      BFD_DBG ("UDP echo source not set - echo not available");
      return 0;
    }
  /*
   * for the echo to work, we need a loopback interface with at least one
   * address with netmask length at most 31 (ip4) or 127 (ip6) so that we can
   * pick an unused address from that subnet
   */
  vnet_sw_interface_t *sw_if =
    vnet_get_sw_interface_or_null (bfd_udp_main.vnet_main,
				   bfd_udp_main.echo_source_sw_if_index);
  if (sw_if && sw_if->flags & VNET_SW_INTERFACE_FLAG_ADMIN_UP)
    {
      if (BFD_TRANSPORT_UDP4 == transport)
	{
	  ip4_main_t *im = &ip4_main;
	  ip_interface_address_t *ia = NULL;
          foreach_ip_interface_address (&im->lookup_main, ia,
                                        bfd_udp_main.echo_source_sw_if_index,
                                        0 /* honor unnumbered */, ({
                                          if (ia->address_length <= 31)
                                            {
                                              return 1;
                                            }
                                        }));
	}
      else if (BFD_TRANSPORT_UDP6 == transport)
	{
	  ip6_main_t *im = &ip6_main;
	  ip_interface_address_t *ia = NULL;
          foreach_ip_interface_address (&im->lookup_main, ia,
                                        bfd_udp_main.echo_source_sw_if_index,
                                        0 /* honor unnumbered */, ({
                                          if (ia->address_length <= 127)
                                            {
                                              return 1;
                                            }
                                        }));
	}
    }
  BFD_DBG ("No usable IP address for UDP echo - echo not available");
  return 0;
}

static u16
bfd_udp_bs_idx_to_sport (u32 bs_idx)
{
  /* The source port MUST be in the range 49152 through 65535. The same UDP
   * source port number MUST be used for all BFD Control packets associated
   * with a particular session.  The source port number SHOULD be unique among
   * all BFD sessions on the system. If more than 16384 BFD sessions are
   * simultaneously active, UDP source port numbers MAY be reused on
   * multiple sessions, but the number of distinct uses of the same UDP
   * source port number SHOULD be minimized.
   */
  return 49152 + bs_idx % (65535 - 49152 + 1);
}

int
bfd_udp_get_echo_src_ip4 (ip4_address_t * addr)
{
  if (!bfd_udp_main.echo_source_is_set)
    {
      BFD_ERR ("cannot find ip4 address, echo source not set");
      return 0;
    }
  ip_interface_address_t *ia = NULL;
  ip4_main_t *im = &ip4_main;

  foreach_ip_interface_address (
      &im->lookup_main, ia, bfd_udp_main.echo_source_sw_if_index,
      0 /* honor unnumbered */, ({
        ip4_address_t *x =
            ip_interface_address_get_address (&im->lookup_main, ia);
        if (ia->address_length <= 31)
          {
            addr->as_u32 = clib_host_to_net_u32 (x->as_u32);
            /*
             * flip the last bit to get a different address, might be network,
             * we don't care ...
             */
            addr->as_u32 ^= 1;
            addr->as_u32 = clib_net_to_host_u32 (addr->as_u32);
            return 1;
          }
      }));
  BFD_ERR ("cannot find ip4 address, no usable address found");
  return 0;
}

int
bfd_udp_get_echo_src_ip6 (ip6_address_t * addr)
{
  if (!bfd_udp_main.echo_source_is_set)
    {
      BFD_ERR ("cannot find ip6 address, echo source not set");
      return 0;
    }
  ip_interface_address_t *ia = NULL;
  ip6_main_t *im = &ip6_main;

  foreach_ip_interface_address (
      &im->lookup_main, ia, bfd_udp_main.echo_source_sw_if_index,
      0 /* honor unnumbered */, ({
        ip6_address_t *x =
            ip_interface_address_get_address (&im->lookup_main, ia);
        if (ia->address_length <= 127)
          {
            *addr = *x;
            addr->as_u8[15] ^= 1; /* flip the last bit of the address */
            return 1;
          }
      }));
  BFD_ERR ("cannot find ip6 address, no usable address found");
  return 0;
}

void
bfd_udp_get_echo_source (int *is_set, u32 * sw_if_index,
			 int *have_usable_ip4, ip4_address_t * ip4,
			 int *have_usable_ip6, ip6_address_t * ip6)
{
  if (bfd_udp_main.echo_source_is_set)
    {
      *is_set = 1;
      *sw_if_index = bfd_udp_main.echo_source_sw_if_index;
      *have_usable_ip4 = bfd_udp_get_echo_src_ip4 (ip4);
      *have_usable_ip6 = bfd_udp_get_echo_src_ip6 (ip6);
    }
  else
    {
      *is_set = 0;
    }
}

int
bfd_add_udp4_transport (vlib_main_t * vm, u32 bi, const bfd_session_t * bs,
			int is_echo)
{
  const bfd_udp_session_t *bus = &bs->udp;
  const bfd_udp_key_t *key = &bus->key;
  vlib_buffer_t *b = vlib_get_buffer (vm, bi);

  b->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
  vnet_buffer (b)->ip.adj_index[VLIB_RX] = bus->adj_index;
  vnet_buffer (b)->ip.adj_index[VLIB_TX] = bus->adj_index;
  vnet_buffer (b)->sw_if_index[VLIB_RX] = 0;
  vnet_buffer (b)->sw_if_index[VLIB_TX] = ~0;
  typedef struct
  {
    ip4_header_t ip4;
    udp_header_t udp;
  } ip4_udp_headers;
  ip4_udp_headers *headers = NULL;
  vlib_buffer_advance (b, -sizeof (*headers));
  headers = vlib_buffer_get_current (b);
  clib_memset (headers, 0, sizeof (*headers));
  headers->ip4.ip_version_and_header_length = 0x45;
  headers->ip4.ttl = 255;
  headers->ip4.protocol = IP_PROTOCOL_UDP;
  headers->udp.src_port =
    clib_host_to_net_u16 (bfd_udp_bs_idx_to_sport (bs->bs_idx));
  if (is_echo)
    {
      int rv;
      if (!(rv = bfd_udp_get_echo_src_ip4 (&headers->ip4.src_address)))
	{
	  return rv;
	}
      headers->ip4.dst_address.as_u32 = key->local_addr.ip4.as_u32;
      headers->udp.dst_port = clib_host_to_net_u16 (UDP_DST_PORT_bfd_echo4);
    }
  else
    {
      headers->ip4.src_address.as_u32 = key->local_addr.ip4.as_u32;
      headers->ip4.dst_address.as_u32 = key->peer_addr.ip4.as_u32;
      headers->udp.dst_port = clib_host_to_net_u16 (UDP_DST_PORT_bfd4);
    }

  /* fix ip length, checksum and udp length */
  const u16 ip_length = vlib_buffer_length_in_chain (vm, b);

  headers->ip4.length = clib_host_to_net_u16 (ip_length);
  headers->ip4.checksum = ip4_header_checksum (&headers->ip4);

  const u16 udp_length = ip_length - (sizeof (headers->ip4));
  headers->udp.length = clib_host_to_net_u16 (udp_length);
  return 1;
}

int
bfd_add_udp6_transport (vlib_main_t * vm, u32 bi, const bfd_session_t * bs,
			int is_echo)
{
  const bfd_udp_session_t *bus = &bs->udp;
  const bfd_udp_key_t *key = &bus->key;
  vlib_buffer_t *b = vlib_get_buffer (vm, bi);

  b->flags |= VNET_BUFFER_F_LOCALLY_ORIGINATED;
  vnet_buffer (b)->ip.adj_index[VLIB_RX] = bus->adj_index;
  vnet_buffer (b)->ip.adj_index[VLIB_TX] = bus->adj_index;
  vnet_buffer (b)->sw_if_index[VLIB_RX] = 0;
  vnet_buffer (b)->sw_if_index[VLIB_TX] = 0;
  typedef struct
  {
    ip6_header_t ip6;
    udp_header_t udp;
  } ip6_udp_headers;
  ip6_udp_headers *headers = NULL;
  vlib_buffer_advance (b, -sizeof (*headers));
  headers = vlib_buffer_get_current (b);
  clib_memset (headers, 0, sizeof (*headers));
  headers->ip6.ip_version_traffic_class_and_flow_label =
    clib_host_to_net_u32 (0x6 << 28);
  headers->ip6.hop_limit = 255;
  headers->ip6.protocol = IP_PROTOCOL_UDP;
  headers->udp.src_port =
    clib_host_to_net_u16 (bfd_udp_bs_idx_to_sport (bs->bs_idx));
  if (is_echo)
    {
      int rv;
      if (!(rv = bfd_udp_get_echo_src_ip6 (&headers->ip6.src_address)))
	{
	  return rv;
	}
      clib_memcpy_fast (&headers->ip6.dst_address, &key->local_addr.ip6,
			sizeof (headers->ip6.dst_address));

      headers->udp.dst_port = clib_host_to_net_u16 (UDP_DST_PORT_bfd_echo6);
    }
  else
    {
      clib_memcpy_fast (&headers->ip6.src_address, &key->local_addr.ip6,
			sizeof (headers->ip6.src_address));
      clib_memcpy_fast (&headers->ip6.dst_address, &key->peer_addr.ip6,
			sizeof (headers->ip6.dst_address));
      headers->udp.dst_port = clib_host_to_net_u16 (UDP_DST_PORT_bfd6);
    }

  /* fix ip payload length and udp length */
  const u16 udp_length =
    vlib_buffer_length_in_chain (vm, b) - (sizeof (headers->ip6));
  headers->udp.length = clib_host_to_net_u16 (udp_length);
  headers->ip6.payload_length = headers->udp.length;

  /* IPv6 UDP checksum is mandatory */
  int bogus = 0;
  headers->udp.checksum =
    ip6_tcp_udp_icmp_compute_checksum (vm, b, &headers->ip6, &bogus);
  ASSERT (bogus == 0);
  if (headers->udp.checksum == 0)
    {
      headers->udp.checksum = 0xffff;
    }
  return 1;
}

static void
bfd_create_frame_to_next_node (vlib_main_t *vm, vlib_node_runtime_t *rt,
			       u32 bi, const bfd_session_t *bs, u32 next,
			       vlib_combined_counter_main_t *tx_counter)
{
  vlib_buffer_t *b = vlib_get_buffer (vm, bi);
  vlib_node_t *from_node = vlib_get_node (vm, rt->node_index);
  ASSERT (next < vec_len (from_node->next_nodes));
  u32 to_node_index = from_node->next_nodes[next];
  vlib_frame_t *f = vlib_get_frame_to_node (vm, to_node_index);
  u32 *to_next = vlib_frame_vector_args (f);
  to_next[0] = bi;
  f->n_vectors = 1;
  if (b->flags & VLIB_BUFFER_IS_TRACED)
    {
      f->frame_flags |= VLIB_NODE_FLAG_TRACE;
    }
  vlib_put_frame_to_node (vm, to_node_index, f);
  vlib_increment_combined_counter (tx_counter, vm->thread_index, bs->bs_idx, 1,
				   vlib_buffer_length_in_chain (vm, b));
}

int
bfd_udp_calc_next_node (const struct bfd_session_s *bs, u32 * next_node)
{
  vnet_main_t *vnm = vnet_get_main ();
  const bfd_udp_session_t *bus = &bs->udp;
  ip_adjacency_t *adj = adj_get (bus->adj_index);

  /* don't try to send the buffer if the interface is not up */
  if (!vnet_sw_interface_is_up (vnm, bus->key.sw_if_index))
    return 0;

  switch (adj->lookup_next_index)
    {
    case IP_LOOKUP_NEXT_ARP:
      switch (bs->transport)
	{
	case BFD_TRANSPORT_UDP4:
	  *next_node = BFD_TX_IP4_ARP;
	  return 1;
	case BFD_TRANSPORT_UDP6:
	  *next_node = BFD_TX_IP6_NDP;
	  return 1;
	}
      break;
    case IP_LOOKUP_NEXT_REWRITE:
      switch (bs->transport)
	{
	case BFD_TRANSPORT_UDP4:
	  *next_node = BFD_TX_IP4_REWRITE;
	  return 1;
	case BFD_TRANSPORT_UDP6:
	  *next_node = BFD_TX_IP6_REWRITE;
	  return 1;
	}
      break;
    case IP_LOOKUP_NEXT_MIDCHAIN:
      switch (bs->transport)
	{
	case BFD_TRANSPORT_UDP4:
	  *next_node = BFD_TX_IP4_MIDCHAIN;
	  return 1;
	case BFD_TRANSPORT_UDP6:
	  *next_node = BFD_TX_IP6_MIDCHAIN;
	  return 1;
	}
      break;
    default:
      /* drop */
      break;
    }
  return 0;
}

int
bfd_transport_udp4 (vlib_main_t *vm, vlib_node_runtime_t *rt, u32 bi,
		    const struct bfd_session_s *bs, int is_echo)
{
  u32 next_node;
  int rv = bfd_udp_calc_next_node (bs, &next_node);
  bfd_main_t *bm = bfd_udp_main.bfd_main;
  if (rv)
    {
      bfd_create_frame_to_next_node (vm, rt, bi, bs, next_node,
				     is_echo ? &bm->tx_echo_counter :
						     &bm->tx_counter);
    }
  return rv;
}

int
bfd_transport_udp6 (vlib_main_t *vm, vlib_node_runtime_t *rt, u32 bi,
		    const struct bfd_session_s *bs, int is_echo)
{
  u32 next_node;
  int rv = bfd_udp_calc_next_node (bs, &next_node);
  bfd_main_t *bm = bfd_udp_main.bfd_main;
  if (rv)
    {
      bfd_create_frame_to_next_node (vm, rt, bi, bs, next_node,
				     is_echo ? &bm->tx_echo_counter :
						     &bm->tx_counter);
    }
  return rv;
}

static bfd_session_t *
bfd_lookup_session (bfd_udp_main_t * bum, const bfd_udp_key_t * key)
{
  uword *p = mhash_get (&bum->bfd_session_idx_by_bfd_key, key);
  if (p)
    {
      return bfd_find_session_by_idx (bum->bfd_main, *p);
    }
  return 0;
}

static void
bfd_udp_key_init (bfd_udp_key_t * key, u32 sw_if_index,
		  const ip46_address_t * local_addr,
		  const ip46_address_t * peer_addr)
{
  clib_memset (key, 0, sizeof (*key));
  key->sw_if_index = sw_if_index;
  key->local_addr.as_u64[0] = local_addr->as_u64[0];
  key->local_addr.as_u64[1] = local_addr->as_u64[1];
  key->peer_addr.as_u64[0] = peer_addr->as_u64[0];
  key->peer_addr.as_u64[1] = peer_addr->as_u64[1];
}

static vnet_api_error_t
bfd_udp_add_session_internal (vlib_main_t * vm, bfd_udp_main_t * bum,
			      u32 sw_if_index, u32 desired_min_tx_usec,
			      u32 required_min_rx_usec, u8 detect_mult,
			      const ip46_address_t * local_addr,
			      const ip46_address_t * peer_addr,
			      bfd_session_t ** bs_out)
{
  /* get a pool entry and if we end up not needing it, give it back */
  bfd_transport_e t = BFD_TRANSPORT_UDP4;
  if (!ip46_address_is_ip4 (local_addr))
    {
      t = BFD_TRANSPORT_UDP6;
    }
  bfd_session_t *bs = bfd_get_session (bum->bfd_main, t);
  if (!bs)
    {
      return VNET_API_ERROR_BFD_EAGAIN;
    }
  bfd_udp_session_t *bus = &bs->udp;
  clib_memset (bus, 0, sizeof (*bus));
  bus->adj_index = ADJ_INDEX_INVALID;
  bfd_udp_key_t *key = &bus->key;
  bfd_udp_key_init (key, sw_if_index, local_addr, peer_addr);
  const bfd_session_t *tmp = bfd_lookup_session (bum, key);
  if (tmp)
    {
      vlib_log_err (bum->log_class,
		    "duplicate bfd-udp session, existing bs_idx=%d",
		    tmp->bs_idx);
      bfd_put_session (bum->bfd_main, bs);
      return VNET_API_ERROR_BFD_EEXIST;
    }
  mhash_set (&bum->bfd_session_idx_by_bfd_key, key, bs->bs_idx, NULL);
  BFD_DBG ("session created, bs_idx=%u, sw_if_index=%d, local=%U, peer=%U",
	   bs->bs_idx, key->sw_if_index, format_ip46_address,
	   &key->local_addr, IP46_TYPE_ANY, format_ip46_address,
	   &key->peer_addr, IP46_TYPE_ANY);
  vlib_log_info (bum->log_class, "create BFD session: %U",
		 format_bfd_session, bs);
  const ip46_address_t *peer =
    (vnet_sw_interface_is_p2p (vnet_get_main (), key->sw_if_index) ?
       &zero_addr :
       &key->peer_addr);
  if (BFD_TRANSPORT_UDP4 == t)
    {
      bus->adj_index = adj_nbr_add_or_lock (FIB_PROTOCOL_IP4, VNET_LINK_IP4,
					    peer, key->sw_if_index);
      BFD_DBG ("adj_nbr_add_or_lock(FIB_PROTOCOL_IP4, VNET_LINK_IP4, %U, %d) "
	       "returns %d",
	       format_ip46_address, peer, IP46_TYPE_ANY, key->sw_if_index,
	       bus->adj_index);
      ++bum->udp4_sessions_count;
      bfd_udp_update_stat_segment_entry (
	bum->udp4_sessions_count_stat_seg_entry, bum->udp4_sessions_count);
      if (1 == bum->udp4_sessions_count)
	{
	  udp_register_dst_port (vm, UDP_DST_PORT_bfd4,
				 bfd_udp4_input_node.index, 1);
	  udp_register_dst_port (vm, UDP_DST_PORT_bfd_echo4,
				 bfd_udp_echo4_input_node.index, 1);
	}
    }
  else
    {
      bus->adj_index = adj_nbr_add_or_lock (FIB_PROTOCOL_IP6, VNET_LINK_IP6,
					    peer, key->sw_if_index);
      BFD_DBG ("adj_nbr_add_or_lock(FIB_PROTOCOL_IP6, VNET_LINK_IP6, %U, %d) "
	       "returns %d",
	       format_ip46_address, peer, IP46_TYPE_ANY, key->sw_if_index,
	       bus->adj_index);
      ++bum->udp6_sessions_count;
      bfd_udp_update_stat_segment_entry (
	bum->udp6_sessions_count_stat_seg_entry, bum->udp6_sessions_count);
      if (1 == bum->udp6_sessions_count)
	{
	  udp_register_dst_port (vm, UDP_DST_PORT_bfd6,
				 bfd_udp6_input_node.index, 0);
	  udp_register_dst_port (vm, UDP_DST_PORT_bfd_echo6,
				 bfd_udp_echo6_input_node.index, 0);
	}
    }
  *bs_out = bs;
  return bfd_session_set_params (bum->bfd_main, bs, desired_min_tx_usec,
				 required_min_rx_usec, detect_mult);
}

static vnet_api_error_t
bfd_udp_validate_api_input (u32 sw_if_index,
			    const ip46_address_t * local_addr,
			    const ip46_address_t * peer_addr)
{
  bfd_udp_main_t *bum = &bfd_udp_main;
  vnet_sw_interface_t *sw_if =
    vnet_get_sw_interface_or_null (bfd_udp_main.vnet_main, sw_if_index);
  if (!sw_if)
    {
      vlib_log_err (bum->log_class,
		    "got NULL sw_if when getting interface by index %u",
		    sw_if_index);
      return VNET_API_ERROR_INVALID_SW_IF_INDEX;
    }
  if (ip46_address_is_ip4 (local_addr))
    {
      if (!ip46_address_is_ip4 (peer_addr))
	{
	  vlib_log_err (bum->log_class,
			"IP family mismatch (local is ipv4, peer is ipv6)");
	  return VNET_API_ERROR_INVALID_ARGUMENT;
	}
    }
  else
    {
      if (ip46_address_is_ip4 (peer_addr))
	{
	  vlib_log_err (bum->log_class,
			"IP family mismatch (local is ipv6, peer is ipv4)");
	  return VNET_API_ERROR_INVALID_ARGUMENT;
	}
    }

  return 0;
}

static vnet_api_error_t
bfd_udp_find_session_by_api_input (u32 sw_if_index,
				   const ip46_address_t * local_addr,
				   const ip46_address_t * peer_addr,
				   bfd_session_t ** bs_out)
{
  vnet_api_error_t rv =
    bfd_udp_validate_api_input (sw_if_index, local_addr, peer_addr);
  if (!rv)
    {
      bfd_udp_main_t *bum = &bfd_udp_main;
      bfd_udp_key_t key;
      bfd_udp_key_init (&key, sw_if_index, local_addr, peer_addr);
      bfd_session_t *bs = bfd_lookup_session (bum, &key);
      if (bs)
	{
	  *bs_out = bs;
	}
      else
	{
	  vlib_log_err (bum->log_class,
			"BFD session not found, sw_if_index=%u, local=%U, peer=%U",
			sw_if_index, format_ip46_address, local_addr,
			IP46_TYPE_ANY, format_ip46_address, peer_addr,
			IP46_TYPE_ANY);
	  return VNET_API_ERROR_BFD_ENOENT;
	}
    }
  return rv;
}

static vnet_api_error_t
bfd_api_verify_common (u32 sw_if_index, u32 desired_min_tx_usec,
		       u8 detect_mult, const ip46_address_t *local_addr,
		       const ip46_address_t *peer_addr)
{
  bfd_udp_main_t *bum = &bfd_udp_main;
  vnet_api_error_t rv =
    bfd_udp_validate_api_input (sw_if_index, local_addr, peer_addr);
  if (rv)
    {
      return rv;
    }
  if (detect_mult < 1)
    {
      vlib_log_err (bum->log_class, "detect_mult < 1");
      return VNET_API_ERROR_INVALID_ARGUMENT;
    }
  if (desired_min_tx_usec < 1)
    {
      vlib_log_err (bum->log_class, "desired_min_tx_usec < 1");
      return VNET_API_ERROR_INVALID_ARGUMENT;
    }
  return 0;
}

static void
bfd_udp_del_session_internal (vlib_main_t * vm, bfd_session_t * bs)
{
  bfd_udp_main_t *bum = &bfd_udp_main;
  BFD_DBG ("free bfd-udp session, bs_idx=%d", bs->bs_idx);
  bfd_session_stop (bum->bfd_main, bs);
  mhash_unset (&bum->bfd_session_idx_by_bfd_key, &bs->udp.key, NULL);
  adj_unlock (bs->udp.adj_index);
  switch (bs->transport)
    {
    case BFD_TRANSPORT_UDP4:
      --bum->udp4_sessions_count;
      bfd_udp_update_stat_segment_entry (
	bum->udp4_sessions_count_stat_seg_entry, bum->udp4_sessions_count);
      if (!bum->udp4_sessions_count)
	{
	  udp_unregister_dst_port (vm, UDP_DST_PORT_bfd4, 1);
	  udp_unregister_dst_port (vm, UDP_DST_PORT_bfd_echo4, 1);
	}
      break;
    case BFD_TRANSPORT_UDP6:
      --bum->udp6_sessions_count;
      bfd_udp_update_stat_segment_entry (
	bum->udp6_sessions_count_stat_seg_entry, bum->udp6_sessions_count);
      if (!bum->udp6_sessions_count)
	{
	  udp_unregister_dst_port (vm, UDP_DST_PORT_bfd6, 0);
	  udp_unregister_dst_port (vm, UDP_DST_PORT_bfd_echo6, 0);
	}
      break;
    }
  bfd_put_session (bum->bfd_main, bs);
}

static vnet_api_error_t
bfd_udp_add_and_start_session (u32 sw_if_index,
			       const ip46_address_t *local_addr,
			       const ip46_address_t *peer_addr,
			       u32 desired_min_tx_usec,
			       u32 required_min_rx_usec, u8 detect_mult,
			       u8 is_authenticated, u32 conf_key_id,
			       u8 bfd_key_id)
{
  bfd_session_t *bs = NULL;
  vnet_api_error_t rv;

  rv = bfd_udp_add_session_internal (
    vlib_get_main (), &bfd_udp_main, sw_if_index, desired_min_tx_usec,
    required_min_rx_usec, detect_mult, local_addr, peer_addr, &bs);

  if (!rv && is_authenticated)
    {
      rv = bfd_auth_activate (bs, conf_key_id, bfd_key_id,
			      0 /* is not delayed */);
      if (rv)
	{
	  bfd_udp_del_session_internal (vlib_get_main (), bs);
	}
    }
  if (!rv)
    {
      bfd_session_start (bfd_udp_main.bfd_main, bs);
    }

  return rv;
}

vnet_api_error_t
bfd_udp_add_session (u32 sw_if_index, const ip46_address_t * local_addr,
		     const ip46_address_t * peer_addr,
		     u32 desired_min_tx_usec, u32 required_min_rx_usec,
		     u8 detect_mult, u8 is_authenticated, u32 conf_key_id,
		     u8 bfd_key_id)
{
  bfd_main_t *bm = &bfd_main;
  bfd_lock (bm);

  vnet_api_error_t rv = bfd_api_verify_common (
    sw_if_index, desired_min_tx_usec, detect_mult, local_addr, peer_addr);

  if (!rv)
    rv = bfd_udp_add_and_start_session (
      sw_if_index, local_addr, peer_addr, desired_min_tx_usec,
      required_min_rx_usec, detect_mult, is_authenticated, conf_key_id,
      bfd_key_id);

  bfd_unlock (bm);
  return rv;
}

vnet_api_error_t
bfd_udp_upd_session (u32 sw_if_index, const ip46_address_t *local_addr,
		     const ip46_address_t *peer_addr, u32 desired_min_tx_usec,
		     u32 required_min_rx_usec, u8 detect_mult,
		     u8 is_authenticated, u32 conf_key_id, u8 bfd_key_id)
{
  bfd_main_t *bm = &bfd_main;
  bfd_lock (bm);

  vnet_api_error_t rv = bfd_api_verify_common (
    sw_if_index, desired_min_tx_usec, detect_mult, local_addr, peer_addr);
  if (!rv)
    {
      bfd_session_t *bs = NULL;

      rv = bfd_udp_find_session_by_api_input (sw_if_index, local_addr,
					      peer_addr, &bs);
      if (VNET_API_ERROR_BFD_ENOENT == rv)
	rv = bfd_udp_add_and_start_session (
	  sw_if_index, local_addr, peer_addr, desired_min_tx_usec,
	  required_min_rx_usec, detect_mult, is_authenticated, conf_key_id,
	  bfd_key_id);
      else
	rv = bfd_session_set_params (bfd_udp_main.bfd_main, bs,
				     desired_min_tx_usec, required_min_rx_usec,
				     detect_mult);
    }

  bfd_unlock (bm);
  return rv;
}

vnet_api_error_t
bfd_udp_mod_session (u32 sw_if_index, const ip46_address_t *local_addr,
		     const ip46_address_t *peer_addr, u32 desired_min_tx_usec,
		     u32 required_min_rx_usec, u8 detect_mult)
{
  bfd_session_t *bs = NULL;
  bfd_main_t *bm = &bfd_main;
  vnet_api_error_t error;
  bfd_lock (bm);
  vnet_api_error_t rv =
    bfd_udp_find_session_by_api_input (sw_if_index, local_addr, peer_addr,
				       &bs);
  if (rv)
    {
      bfd_unlock (bm);
      return rv;
    }

  error = bfd_session_set_params (bfd_udp_main.bfd_main, bs,
				  desired_min_tx_usec, required_min_rx_usec,
				  detect_mult);
  bfd_unlock (bm);
  return error;
}

vnet_api_error_t
bfd_udp_del_session (u32 sw_if_index,
		     const ip46_address_t * local_addr,
		     const ip46_address_t * peer_addr)
{
  bfd_session_t *bs = NULL;
  bfd_main_t *bm = &bfd_main;
  bfd_lock (bm);
  vnet_api_error_t rv =
    bfd_udp_find_session_by_api_input (sw_if_index, local_addr, peer_addr,
				       &bs);
  if (rv)
    {
      bfd_unlock (bm);
      return rv;
    }
  bfd_udp_del_session_internal (vlib_get_main (), bs);
  bfd_unlock (bm);
  return 0;
}

vnet_api_error_t
bfd_udp_session_set_flags (vlib_main_t * vm, u32 sw_if_index,
			   const ip46_address_t * local_addr,
			   const ip46_address_t * peer_addr, u8 admin_up_down)
{
  bfd_session_t *bs = NULL;
  bfd_main_t *bm = &bfd_main;
  bfd_lock (bm);
  vnet_api_error_t rv =
    bfd_udp_find_session_by_api_input (sw_if_index, local_addr, peer_addr,
				       &bs);
  if (rv)
    {
      bfd_unlock (bm);
      return rv;
    }
  bfd_session_set_flags (vm, bs, admin_up_down);
  bfd_unlock (bm);
  return 0;
}

vnet_api_error_t
bfd_udp_auth_activate (u32 sw_if_index,
		       const ip46_address_t * local_addr,
		       const ip46_address_t * peer_addr,
		       u32 conf_key_id, u8 key_id, u8 is_delayed)
{
  bfd_main_t *bm = &bfd_main;
  bfd_lock (bm);
  vnet_api_error_t error;

  bfd_session_t *bs = NULL;
  vnet_api_error_t rv =
    bfd_udp_find_session_by_api_input (sw_if_index, local_addr, peer_addr,
				       &bs);
  if (rv)
    {
      bfd_unlock (bm);
      return rv;
    }
  error = bfd_auth_activate (bs, conf_key_id, key_id, is_delayed);
  bfd_unlock (bm);
  return error;
}

vnet_api_error_t
bfd_udp_auth_deactivate (u32 sw_if_index,
			 const ip46_address_t * local_addr,
			 const ip46_address_t * peer_addr, u8 is_delayed)
{
  bfd_main_t *bm = &bfd_main;
  vnet_api_error_t error;
  bfd_lock (bm);
  bfd_session_t *bs = NULL;
  vnet_api_error_t rv =
    bfd_udp_find_session_by_api_input (sw_if_index, local_addr, peer_addr,
				       &bs);
  if (rv)
    {
      bfd_unlock (bm);
      return rv;
    }
  error = bfd_auth_deactivate (bs, is_delayed);
  bfd_unlock (bm);
  return error;
}

typedef enum
{
  BFD_UDP_INPUT_NEXT_NORMAL,
  BFD_UDP_INPUT_NEXT_REPLY_ARP,
  BFD_UDP_INPUT_NEXT_REPLY_REWRITE,
  BFD_UDP_INPUT_NEXT_REPLY_MIDCHAIN,
  BFD_UDP_INPUT_N_NEXT,
} bfd_udp_input_next_t;

typedef enum
{
  BFD_UDP_ECHO_INPUT_NEXT_NORMAL,
  BFD_UDP_ECHO_INPUT_NEXT_REPLY_ARP,
  BFD_UDP_ECHO_INPUT_NEXT_REPLY_REWRITE,
  BFD_UDP_ECHO_INPUT_N_NEXT,
} bfd_udp_echo_input_next_t;

static_always_inline vl_counter_bfd_udp_enum_t
bfd_error_to_udp (bfd_error_t e)
{
  /* The UDP error is a super set of the proto independent errors */
  return ((vl_counter_bfd_udp_enum_t) e);
}

static void
bfd_udp4_find_headers (vlib_buffer_t * b, ip4_header_t ** ip4,
		       udp_header_t ** udp)
{
  /* sanity check first */
  const i32 start = vnet_buffer (b)->l3_hdr_offset;
  if (start < -(signed) sizeof (b->pre_data))
    {
      BFD_ERR ("Start of ip header is before pre_data, ignoring");
      *ip4 = NULL;
      *udp = NULL;
      return;
    }
  *ip4 = (ip4_header_t *) (b->data + start);
  if ((u8 *) * ip4 > (u8 *) vlib_buffer_get_current (b))
    {
      BFD_ERR ("Start of ip header is beyond current data, ignoring");
      *ip4 = NULL;
      *udp = NULL;
      return;
    }
  *udp = (udp_header_t *) ((*ip4) + 1);
}

static vl_counter_bfd_udp_enum_t
bfd_udp4_verify_transport (const ip4_header_t *ip4, const udp_header_t *udp,
			   const bfd_session_t *bs)
{
  const bfd_udp_session_t *bus = &bs->udp;
  const bfd_udp_key_t *key = &bus->key;
  if (ip4->src_address.as_u32 != key->peer_addr.ip4.as_u32)
    {
      BFD_ERR ("IPv4 src addr mismatch, got %U, expected %U",
	       format_ip4_address, ip4->src_address.as_u8, format_ip4_address,
	       key->peer_addr.ip4.as_u8);
      return BFD_UDP_ERROR_SRC_MISMATCH;
    }
  if (ip4->dst_address.as_u32 != key->local_addr.ip4.as_u32)
    {
      BFD_ERR ("IPv4 dst addr mismatch, got %U, expected %U",
	       format_ip4_address, ip4->dst_address.as_u8, format_ip4_address,
	       key->local_addr.ip4.as_u8);
      return BFD_UDP_ERROR_DST_MISMATCH;
    }
  const u8 expected_ttl = 255;
  if (ip4->ttl != expected_ttl)
    {
      BFD_ERR ("IPv4 unexpected TTL value %u, expected %u", ip4->ttl,
	       expected_ttl);
      return BFD_UDP_ERROR_TTL;
    }
  if (clib_net_to_host_u16 (udp->src_port) < 49152)
    {
      BFD_ERR ("Invalid UDP src port %u, out of range <49152,65535>",
	       udp->src_port);
    }
  return BFD_UDP_ERROR_NONE;
}

typedef struct
{
  u32 bs_idx;
  bfd_pkt_t pkt;
} bfd_rpc_update_t;

static bfd_error_t
bfd_rpc_update_session (vlib_main_t *vm, u32 bs_idx, const bfd_pkt_t *pkt)
{
  bfd_main_t *bm = &bfd_main;
  bfd_error_t err;
  bfd_lock (bm);
  err = bfd_consume_pkt (vm, bm, pkt, bs_idx);
  bfd_unlock (bm);

  return err;
}

static vl_counter_bfd_udp_enum_t
bfd_udp4_scan (vlib_main_t *vm, vlib_buffer_t *b, bfd_session_t **bs_out)
{
  const bfd_pkt_t *pkt = vlib_buffer_get_current (b);
  if (sizeof (*pkt) > b->current_length)
    {
      BFD_ERR
	("Payload size %d too small to hold bfd packet of minimum size %d",
	 b->current_length, sizeof (*pkt));
      return BFD_UDP_ERROR_BAD;
    }
  ip4_header_t *ip4;
  udp_header_t *udp;
  bfd_udp4_find_headers (b, &ip4, &udp);
  if (!ip4 || !udp)
    {
      BFD_ERR ("Couldn't find ip4 or udp header");
      return BFD_UDP_ERROR_BAD;
    }
  const u32 udp_payload_length = udp->length - sizeof (*udp);
  if (pkt->head.length > udp_payload_length)
    {
      BFD_ERR
	("BFD packet length is larger than udp payload length (%u > %u)",
	 pkt->head.length, udp_payload_length);
      return BFD_UDP_ERROR_LENGTH;
    }
  vl_counter_bfd_udp_enum_t err;
  if (BFD_UDP_ERROR_NONE !=
      (err = bfd_error_to_udp (bfd_verify_pkt_common (pkt))))
    {
      return err;
    }
  bfd_session_t *bs = NULL;
  if (pkt->your_disc)
    {
      BFD_DBG ("Looking up BFD session using discriminator %u",
	       pkt->your_disc);
      bs = bfd_find_session_by_disc (bfd_udp_main.bfd_main, pkt->your_disc);
    }
  else
    {
      bfd_udp_key_t key;
      clib_memset (&key, 0, sizeof (key));
      key.sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_RX];
      key.local_addr.ip4.as_u32 = ip4->dst_address.as_u32;
      key.peer_addr.ip4.as_u32 = ip4->src_address.as_u32;
      BFD_DBG ("Looking up BFD session using key (sw_if_index=%u, local=%U, "
	       "peer=%U)",
	       key.sw_if_index, format_ip4_address, key.local_addr.ip4.as_u8,
	       format_ip4_address, key.peer_addr.ip4.as_u8);
      bs = bfd_lookup_session (&bfd_udp_main, &key);
    }
  if (!bs)
    {
      BFD_ERR ("BFD session lookup failed - no session matches BFD pkt");
      return BFD_UDP_ERROR_NO_SESSION;
    }
  BFD_DBG ("BFD session found, bs_idx=%u", bs->bs_idx);
  if (!bfd_verify_pkt_auth (vm, pkt, b->current_length, bs))
    {
      BFD_ERR ("Packet verification failed, dropping packet");
      return BFD_UDP_ERROR_FAILED_VERIFICATION;
    }
  if (BFD_UDP_ERROR_NONE != (err = bfd_udp4_verify_transport (ip4, udp, bs)))
    {
      return err;
    }
  err = bfd_error_to_udp (bfd_rpc_update_session (vm, bs->bs_idx, pkt));
  *bs_out = bs;
  return err;
}

static void
bfd_udp6_find_headers (vlib_buffer_t * b, ip6_header_t ** ip6,
		       udp_header_t ** udp)
{
  /* sanity check first */
  const i32 start = vnet_buffer (b)->l3_hdr_offset;
  if (start < -(signed) sizeof (b->pre_data))
    {
      BFD_ERR ("Start of ip header is before pre_data, ignoring");
      *ip6 = NULL;
      *udp = NULL;
      return;
    }
  *ip6 = (ip6_header_t *) (b->data + start);
  if ((u8 *) * ip6 > (u8 *) vlib_buffer_get_current (b))
    {
      BFD_ERR ("Start of ip header is beyond current data, ignoring");
      *ip6 = NULL;
      *udp = NULL;
      return;
    }
  if ((*ip6)->protocol != IP_PROTOCOL_UDP)
    {
      BFD_ERR ("Unexpected protocol in IPv6 header '%u', expected '%u' (== "
	       "IP_PROTOCOL_UDP)", (*ip6)->protocol, IP_PROTOCOL_UDP);
      *ip6 = NULL;
      *udp = NULL;
      return;
    }
  *udp = (udp_header_t *) ((*ip6) + 1);
}

static vl_counter_bfd_udp_enum_t
bfd_udp6_verify_transport (const ip6_header_t *ip6, const udp_header_t *udp,
			   const bfd_session_t *bs)
{
  const bfd_udp_session_t *bus = &bs->udp;
  const bfd_udp_key_t *key = &bus->key;
  if (ip6->src_address.as_u64[0] != key->peer_addr.ip6.as_u64[0] &&
      ip6->src_address.as_u64[1] != key->peer_addr.ip6.as_u64[1])
    {
      BFD_ERR ("IP src addr mismatch, got %U, expected %U",
	       format_ip6_address, ip6, format_ip6_address,
	       &key->peer_addr.ip6);
      return BFD_UDP_ERROR_SRC_MISMATCH;
    }
  if (ip6->dst_address.as_u64[0] != key->local_addr.ip6.as_u64[0] &&
      ip6->dst_address.as_u64[1] != key->local_addr.ip6.as_u64[1])
    {
      BFD_ERR ("IP dst addr mismatch, got %U, expected %U",
	       format_ip6_address, ip6, format_ip6_address,
	       &key->local_addr.ip6);
      return BFD_UDP_ERROR_DST_MISMATCH;
    }
  const u8 expected_hop_limit = 255;
  if (ip6->hop_limit != expected_hop_limit)
    {
      BFD_ERR ("IPv6 unexpected hop-limit value %u, expected %u",
	       ip6->hop_limit, expected_hop_limit);
      return BFD_UDP_ERROR_TTL;
    }
  if (clib_net_to_host_u16 (udp->src_port) < 49152)
    {
      BFD_ERR ("Invalid UDP src port %u, out of range <49152,65535>",
	       udp->src_port);
    }
  return BFD_UDP_ERROR_NONE;
}

static vl_counter_bfd_udp_enum_t
bfd_udp6_scan (vlib_main_t *vm, vlib_buffer_t *b, bfd_session_t **bs_out)
{
  const bfd_pkt_t *pkt = vlib_buffer_get_current (b);
  if (sizeof (*pkt) > b->current_length)
    {
      BFD_ERR
	("Payload size %d too small to hold bfd packet of minimum size %d",
	 b->current_length, sizeof (*pkt));
      return BFD_UDP_ERROR_BAD;
    }
  ip6_header_t *ip6;
  udp_header_t *udp;
  bfd_udp6_find_headers (b, &ip6, &udp);
  if (!ip6 || !udp)
    {
      BFD_ERR ("Couldn't find ip6 or udp header");
      return BFD_UDP_ERROR_BAD;
    }
  const u32 udp_payload_length = udp->length - sizeof (*udp);
  if (pkt->head.length > udp_payload_length)
    {
      BFD_ERR
	("BFD packet length is larger than udp payload length (%u > %u)",
	 pkt->head.length, udp_payload_length);
      return BFD_UDP_ERROR_BAD;
    }
  vl_counter_bfd_udp_enum_t err;
  if (BFD_UDP_ERROR_NONE !=
      (err = bfd_error_to_udp (bfd_verify_pkt_common (pkt))))
    {
      return err;
    }
  bfd_session_t *bs = NULL;
  if (pkt->your_disc)
    {
      BFD_DBG ("Looking up BFD session using discriminator %u",
	       pkt->your_disc);
      bs = bfd_find_session_by_disc (bfd_udp_main.bfd_main, pkt->your_disc);
    }
  else
    {
      bfd_udp_key_t key;
      clib_memset (&key, 0, sizeof (key));
      key.sw_if_index = vnet_buffer (b)->sw_if_index[VLIB_RX];
      key.local_addr.ip6.as_u64[0] = ip6->dst_address.as_u64[0];
      key.local_addr.ip6.as_u64[1] = ip6->dst_address.as_u64[1];
      key.peer_addr.ip6.as_u64[0] = ip6->src_address.as_u64[0];
      key.peer_addr.ip6.as_u64[1] = ip6->src_address.as_u64[1];
      BFD_DBG ("Looking up BFD session using key (sw_if_index=%u, local=%U, "
	       "peer=%U)",
	       key.sw_if_index, format_ip6_address, &key.local_addr,
	       format_ip6_address, &key.peer_addr);
      bs = bfd_lookup_session (&bfd_udp_main, &key);
    }
  if (!bs)
    {
      BFD_ERR ("BFD session lookup failed - no session matches BFD pkt");
      return BFD_UDP_ERROR_NO_SESSION;
    }
  BFD_DBG ("BFD session found, bs_idx=%u", bs->bs_idx);
  if (!bfd_verify_pkt_auth (vm, pkt, b->current_length, bs))
    {
      BFD_ERR ("Packet verification failed, dropping packet");
      return BFD_UDP_ERROR_FAILED_VERIFICATION;
    }
  if (BFD_UDP_ERROR_NONE != (err = bfd_udp6_verify_transport (ip6, udp, bs)))
    {
      return err;
    }
  err = bfd_error_to_udp (bfd_rpc_update_session (vm, bs->bs_idx, pkt));
  *bs_out = bs;
  return err;
}

/*
 * Process a frame of bfd packets
 * Expect 1 packet / frame
 */
static uword
bfd_udp_input (vlib_main_t * vm, vlib_node_runtime_t * rt,
	       vlib_frame_t * f, int is_ipv6)
{
  u32 n_left_from, *from;
  bfd_input_trace_t *t0;
  bfd_main_t *bm = &bfd_main;

  from = vlib_frame_vector_args (f);	/* array of buffer indices */
  n_left_from = f->n_vectors;	/* number of buffer indices */

  while (n_left_from > 0)
    {
      u32 bi0;
      vlib_buffer_t *b0;
      u32 next0, error0;

      bi0 = from[0];
      b0 = vlib_get_buffer (vm, bi0);

      bfd_session_t *bs = NULL;

      /* If this pkt is traced, snapshot the data */
      if (b0->flags & VLIB_BUFFER_IS_TRACED)
	{
	  u64 len;
	  t0 = vlib_add_trace (vm, rt, b0, sizeof (*t0));
	  len = (b0->current_length < sizeof (t0->data)) ? b0->current_length
	    : sizeof (t0->data);
	  t0->len = len;
	  clib_memcpy_fast (t0->data, vlib_buffer_get_current (b0), len);
	}

      /* scan this bfd pkt. error0 is the counter index to bmp */
      bfd_lock (bm);
      if (is_ipv6)
	{
	  error0 = bfd_udp6_scan (vm, b0, &bs);
	}
      else
	{
	  error0 = bfd_udp4_scan (vm, b0, &bs);
	}
      b0->error = rt->errors[error0];

      next0 = BFD_UDP_INPUT_NEXT_NORMAL;
      if (BFD_UDP_ERROR_NONE == error0)
	{
	  vlib_increment_combined_counter (
	    &bm->rx_counter, vm->thread_index, bs->bs_idx, 1,
	    vlib_buffer_length_in_chain (vm, b0));
	  /*
	   *  if everything went fine, check for poll bit, if present, re-use
	   *  the buffer and based on (now updated) session parameters, send
	   *  the final packet back
	   */
	  const bfd_pkt_t *pkt = vlib_buffer_get_current (b0);
	  if (bfd_pkt_get_poll (pkt))
	    {
	      b0->current_data = 0;
	      b0->current_length = 0;
	      bfd_init_final_control_frame (vm, b0, bs);
	      if (is_ipv6)
		{
		  vlib_node_increment_counter (vm, bfd_udp6_input_node.index,
					       error0, 1);
		}
	      else
		{
		  vlib_node_increment_counter (vm, bfd_udp4_input_node.index,
					       error0, 1);
		}
	      const bfd_udp_session_t *bus = &bs->udp;
	      ip_adjacency_t *adj = adj_get (bus->adj_index);
	      switch (adj->lookup_next_index)
		{
		case IP_LOOKUP_NEXT_ARP:
		  next0 = BFD_UDP_INPUT_NEXT_REPLY_ARP;
		  break;
		case IP_LOOKUP_NEXT_REWRITE:
		  next0 = BFD_UDP_INPUT_NEXT_REPLY_REWRITE;
		  break;
		case IP_LOOKUP_NEXT_MIDCHAIN:
		  next0 = BFD_UDP_INPUT_NEXT_REPLY_MIDCHAIN;
		  break;
		default:
		  /* drop */
		  break;
		}
	    }
	}
      bfd_unlock (bm);
      vlib_set_next_frame_buffer (vm, rt, next0, bi0);

      from += 1;
      n_left_from -= 1;
    }

  return f->n_vectors;
}

static uword
bfd_udp4_input (vlib_main_t * vm, vlib_node_runtime_t * rt, vlib_frame_t * f)
{
  return bfd_udp_input (vm, rt, f, 0);
}

/*
 * bfd input graph node declaration
 */
VLIB_REGISTER_NODE (bfd_udp4_input_node, static) = {
  .function = bfd_udp4_input,
  .name = "bfd-udp4-input",
  .vector_size = sizeof (u32),
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_errors = BFD_UDP_N_ERROR,
  .error_counters = bfd_udp_error_counters,

  .format_trace = bfd_input_format_trace,

  .n_next_nodes = BFD_UDP_INPUT_N_NEXT,
  .next_nodes =
      {
              [BFD_UDP_INPUT_NEXT_NORMAL] = "error-drop",
              [BFD_UDP_INPUT_NEXT_REPLY_ARP] = "ip4-arp",
              [BFD_UDP_INPUT_NEXT_REPLY_REWRITE] = "ip4-lookup",
              [BFD_UDP_INPUT_NEXT_REPLY_MIDCHAIN] = "ip4-midchain",
      },
};

static uword
bfd_udp6_input (vlib_main_t * vm, vlib_node_runtime_t * rt, vlib_frame_t * f)
{
  return bfd_udp_input (vm, rt, f, 1);
}

VLIB_REGISTER_NODE (bfd_udp6_input_node, static) = {
  .function = bfd_udp6_input,
  .name = "bfd-udp6-input",
  .vector_size = sizeof (u32),
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_errors = BFD_UDP_N_ERROR,
  .error_counters = bfd_udp_error_counters,

  .format_trace = bfd_input_format_trace,

  .n_next_nodes = BFD_UDP_INPUT_N_NEXT,
  .next_nodes =
      {
              [BFD_UDP_INPUT_NEXT_NORMAL] = "error-drop",
              [BFD_UDP_INPUT_NEXT_REPLY_ARP] = "ip6-discover-neighbor",
              [BFD_UDP_INPUT_NEXT_REPLY_REWRITE] = "ip6-lookup",
              [BFD_UDP_INPUT_NEXT_REPLY_MIDCHAIN] = "ip6-midchain",
      },
};

/*
 * Process a frame of bfd echo packets
 * Expect 1 packet / frame
 */
static uword
bfd_udp_echo_input (vlib_main_t * vm, vlib_node_runtime_t * rt,
		    vlib_frame_t * f, int is_ipv6)
{
  u32 n_left_from, *from;
  bfd_input_trace_t *t0;
  bfd_main_t *bm = &bfd_main;

  from = vlib_frame_vector_args (f);	/* array of buffer indices */
  n_left_from = f->n_vectors;	/* number of buffer indices */

  while (n_left_from > 0)
    {
      u32 bi0;
      vlib_buffer_t *b0;
      u32 next0;

      bi0 = from[0];
      b0 = vlib_get_buffer (vm, bi0);

      /* If this pkt is traced, snapshot the data */
      if (b0->flags & VLIB_BUFFER_IS_TRACED)
	{
	  u64 len;
	  t0 = vlib_add_trace (vm, rt, b0, sizeof (*t0));
	  len = (b0->current_length < sizeof (t0->data)) ? b0->current_length
	    : sizeof (t0->data);
	  t0->len = len;
	  clib_memcpy_fast (t0->data, vlib_buffer_get_current (b0), len);
	}

      bfd_session_t *bs = NULL;
      bfd_lock (bm);
      if ((bs = bfd_consume_echo_pkt (vm, bfd_udp_main.bfd_main, b0)))
	{
	  b0->error = rt->errors[BFD_UDP_ERROR_NONE];
	  next0 = BFD_UDP_ECHO_INPUT_NEXT_NORMAL;
	}
      else
	{
	  /* loop back the packet */
	  b0->error = rt->errors[BFD_UDP_ERROR_NONE];
	  if (is_ipv6)
	    {
	      vlib_node_increment_counter (vm, bfd_udp_echo6_input_node.index,
					   BFD_UDP_ERROR_NONE, 1);
	    }
	  else
	    {
	      vlib_node_increment_counter (vm, bfd_udp_echo4_input_node.index,
					   BFD_UDP_ERROR_NONE, 1);
	    }
	  next0 = BFD_UDP_ECHO_INPUT_NEXT_REPLY_REWRITE;
	}

      bfd_unlock (bm);

      if (bs)
	{
	  vlib_increment_combined_counter (
	    &bm->rx_echo_counter, vm->thread_index, bs->bs_idx, 1,
	    vlib_buffer_length_in_chain (vm, b0));
	}

      vlib_set_next_frame_buffer (vm, rt, next0, bi0);

      from += 1;
      n_left_from -= 1;
    }

  return f->n_vectors;
}

static uword
bfd_udp_echo4_input (vlib_main_t * vm, vlib_node_runtime_t * rt,
		     vlib_frame_t * f)
{
  return bfd_udp_echo_input (vm, rt, f, 0);
}

u8 *
bfd_echo_input_format_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  const bfd_udp_echo_input_trace_t *t =
    va_arg (*args, bfd_udp_echo_input_trace_t *);
  if (t->len > STRUCT_SIZE_OF (bfd_pkt_t, head))
    {
      s = format (s, "BFD ECHO:\n");
      s = format (s, "    data: %U", format_hexdump, t->data, t->len);
    }

  return s;
}

/*
 * bfd input graph node declaration
 */
VLIB_REGISTER_NODE (bfd_udp_echo4_input_node, static) = {
  .function = bfd_udp_echo4_input,
  .name = "bfd-udp-echo4-input",
  .vector_size = sizeof (u32),
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_errors = BFD_UDP_N_ERROR,
  .error_counters = bfd_udp_error_counters,

  .format_trace = bfd_echo_input_format_trace,

  .n_next_nodes = BFD_UDP_ECHO_INPUT_N_NEXT,
  .next_nodes =
      {
              [BFD_UDP_ECHO_INPUT_NEXT_NORMAL] = "error-drop",
              [BFD_UDP_ECHO_INPUT_NEXT_REPLY_ARP] = "ip4-arp",
              [BFD_UDP_ECHO_INPUT_NEXT_REPLY_REWRITE] = "ip4-lookup",
      },
};

static uword
bfd_udp_echo6_input (vlib_main_t * vm, vlib_node_runtime_t * rt,
		     vlib_frame_t * f)
{
  return bfd_udp_echo_input (vm, rt, f, 1);
}

VLIB_REGISTER_NODE (bfd_udp_echo6_input_node, static) = {
  .function = bfd_udp_echo6_input,
  .name = "bfd-udp-echo6-input",
  .vector_size = sizeof (u32),
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_errors = BFD_UDP_N_ERROR,
  .error_counters = bfd_udp_error_counters,

  .format_trace = bfd_echo_input_format_trace,

  .n_next_nodes = BFD_UDP_ECHO_INPUT_N_NEXT,
  .next_nodes =
      {
              [BFD_UDP_ECHO_INPUT_NEXT_NORMAL] = "error-drop",
              [BFD_UDP_ECHO_INPUT_NEXT_REPLY_ARP] = "ip6-discover-neighbor",
              [BFD_UDP_ECHO_INPUT_NEXT_REPLY_REWRITE] = "ip6-lookup",
      },
};


static clib_error_t *
bfd_udp_sw_if_add_del (CLIB_UNUSED (vnet_main_t *vnm), u32 sw_if_index,
		       u32 is_create)
{
  u32 *to_be_freed = NULL;
  bfd_udp_main_t *bum = &bfd_udp_main;
  BFD_DBG ("sw_if_add_del called, sw_if_index=%u, is_create=%u", sw_if_index,
	   is_create);
  if (!is_create)
    {
      bfd_session_t *bs;
      pool_foreach (bs, bum->bfd_main->sessions)
	{
	  if (bs->transport != BFD_TRANSPORT_UDP4 &&
	      bs->transport != BFD_TRANSPORT_UDP6)
	    {
	      continue;
	    }
	  if (bs->udp.key.sw_if_index != sw_if_index)
	    {
	      continue;
	    }
	  vec_add1 (to_be_freed, bs->bs_idx);
	}
    }
  u32 *bs_idx;
  vec_foreach (bs_idx, to_be_freed)
    {
      bfd_session_t *bs = pool_elt_at_index (bum->bfd_main->sessions, *bs_idx);
      vlib_log_notice (bum->log_class,
		       "removal of sw_if_index=%u forces removal of bfd "
		       "session with bs_idx=%u",
		       sw_if_index, bs->bs_idx);
      bfd_session_set_flags (vlib_get_main (), bs, 0);
      bfd_udp_del_session_internal (vlib_get_main (), bs);
    }
  return 0;
}

VNET_SW_INTERFACE_ADD_DEL_FUNCTION (bfd_udp_sw_if_add_del);

clib_error_t *
bfd_udp_stats_init (bfd_udp_main_t *bum)
{
  const char *name4 = "/bfd/udp4/sessions";
  bum->udp4_sessions_count_stat_seg_entry = vlib_stats_add_gauge ("%s", name4);

  vlib_stats_set_gauge (bum->udp4_sessions_count_stat_seg_entry, 0);
  if (~0 == bum->udp4_sessions_count_stat_seg_entry)
    {
      return clib_error_return (
	0, "Could not create stat segment entry for %s", name4);
    }
  const char *name6 = "/bfd/udp6/sessions";
  bum->udp6_sessions_count_stat_seg_entry = vlib_stats_add_gauge ("%s", name6);

  vlib_stats_set_gauge (bum->udp6_sessions_count_stat_seg_entry, 0);
  if (~0 == bum->udp6_sessions_count_stat_seg_entry)
    {
      return clib_error_return (
	0, "Could not create stat segment entry for %s", name6);
    }

  return 0;
}

/*
 * setup function
 */
static clib_error_t *
bfd_udp_init (vlib_main_t * vm)
{
  bfd_udp_main.udp4_sessions_count = 0;
  bfd_udp_main.udp6_sessions_count = 0;
  mhash_init (&bfd_udp_main.bfd_session_idx_by_bfd_key, sizeof (uword),
	      sizeof (bfd_udp_key_t));
  bfd_udp_main.bfd_main = &bfd_main;
  bfd_udp_main.vnet_main = vnet_get_main ();
  bfd_udp_stats_init (&bfd_udp_main);

  bfd_udp_main.log_class = vlib_log_register_class ("bfd", "udp");
  vlib_log_debug (bfd_udp_main.log_class, "initialized");
  return 0;
}

VLIB_INIT_FUNCTION (bfd_udp_init);

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */