summaryrefslogtreecommitdiff
path: root/sbin/isakmpd/exchange.c
blob: 57704ca9d2b6667c656c47eae22bf35e88dd2c66 (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
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
/*	$OpenBSD: exchange.c,v 1.74 2002/11/21 12:09:20 ho Exp $	*/
/*	$EOM: exchange.c,v 1.143 2000/12/04 00:02:25 angelos Exp $	*/

/*
 * Copyright (c) 1998, 1999, 2000, 2001 Niklas Hallqvist.  All rights reserved.
 * Copyright (c) 1999, 2001 Angelos D. Keromytis.  All rights reserved.
 * Copyright (c) 1999, 2000, 2002 Håkan Olsson.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Ericsson Radio Systems.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This code was written under funding by Ericsson Radio Systems.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>

#include "sysdep.h"

#include "cert.h"
#include "conf.h"
#include "connection.h"
#include "constants.h"
#include "cookie.h"
#include "crypto.h"
#include "doi.h"
#include "exchange.h"
#include "ipsec_num.h"
#include "isakmp.h"
#ifdef USE_ISAKMP_CFG
#include "isakmp_cfg.h"
#endif
#include "libcrypto.h"
#include "log.h"
#include "message.h"
#include "timer.h"
#include "transport.h"
#include "ipsec.h"
#include "sa.h"
#include "util.h"
#include "key.h"

/* Initial number of bits from the cookies used as hash.  */
#define INITIAL_BUCKET_BITS 6

/*
 * Don't try to use more bits than this as a hash.
 * We only XOR 16 bits so going above that means changing the code below
 * too.
 */
#define MAX_BUCKET_BITS 16

static void exchange_dump (char *, struct exchange *);
static void exchange_free_aux (void *);
static struct exchange *exchange_lookup_active (char *, int);
#if 0
static void exchange_resize (void);
#endif

static LIST_HEAD (exchange_list, exchange) *exchange_tab;

/* Works both as a maximum index and a mask.  */
static int bucket_mask;

/*
 * Validation scripts used to test messages for correct content of
 * payloads depending on the exchange type.
 */
int16_t script_base[] = {
  ISAKMP_PAYLOAD_SA,		/* Initiator -> responder.  */
  ISAKMP_PAYLOAD_NONCE,
  EXCHANGE_SCRIPT_SWITCH,
  ISAKMP_PAYLOAD_SA,		/* Responder -> initiator.  */
  ISAKMP_PAYLOAD_NONCE,
  EXCHANGE_SCRIPT_SWITCH,
  ISAKMP_PAYLOAD_KEY_EXCH,	/* Initiator -> responder.  */
  ISAKMP_PAYLOAD_ID,
  EXCHANGE_SCRIPT_AUTH,
  EXCHANGE_SCRIPT_SWITCH,
  ISAKMP_PAYLOAD_KEY_EXCH,	/* Responder -> initiator.  */
  ISAKMP_PAYLOAD_ID,
  EXCHANGE_SCRIPT_AUTH,
  EXCHANGE_SCRIPT_END
};

int16_t script_identity_protection[] = {
  ISAKMP_PAYLOAD_SA,		/* Initiator -> responder.  */
  EXCHANGE_SCRIPT_SWITCH,
  ISAKMP_PAYLOAD_SA,		/* Responder -> initiator.  */
  EXCHANGE_SCRIPT_SWITCH,
  ISAKMP_PAYLOAD_KEY_EXCH,	/* Initiator -> responder.  */
  ISAKMP_PAYLOAD_NONCE,
  EXCHANGE_SCRIPT_SWITCH,
  ISAKMP_PAYLOAD_KEY_EXCH,	/* Responder -> initiator.  */
  ISAKMP_PAYLOAD_NONCE,
  EXCHANGE_SCRIPT_SWITCH,
  ISAKMP_PAYLOAD_ID,		/* Initiator -> responder.  */
  EXCHANGE_SCRIPT_AUTH,
  EXCHANGE_SCRIPT_SWITCH,
  ISAKMP_PAYLOAD_ID,		/* Responder -> initiator.  */
  EXCHANGE_SCRIPT_AUTH,
  EXCHANGE_SCRIPT_END
};

int16_t script_authentication_only[] = {
  ISAKMP_PAYLOAD_SA,		/* Initiator -> responder.  */
  ISAKMP_PAYLOAD_NONCE,
  EXCHANGE_SCRIPT_SWITCH,
  ISAKMP_PAYLOAD_SA,		/* Responder -> initiator.  */
  ISAKMP_PAYLOAD_NONCE,
  ISAKMP_PAYLOAD_ID,
  EXCHANGE_SCRIPT_AUTH,
  EXCHANGE_SCRIPT_SWITCH,
  ISAKMP_PAYLOAD_ID,		/* Initiator -> responder.  */
  EXCHANGE_SCRIPT_AUTH,
  EXCHANGE_SCRIPT_END
};

#ifdef USE_AGGRESSIVE
int16_t script_aggressive[] = {
  ISAKMP_PAYLOAD_SA,		/* Initiator -> responder.  */
  ISAKMP_PAYLOAD_KEY_EXCH,
  ISAKMP_PAYLOAD_NONCE,
  ISAKMP_PAYLOAD_ID,
  EXCHANGE_SCRIPT_SWITCH,
  ISAKMP_PAYLOAD_SA,		/* Responder -> initiator.  */
  ISAKMP_PAYLOAD_KEY_EXCH,
  ISAKMP_PAYLOAD_NONCE,
  ISAKMP_PAYLOAD_ID,
  EXCHANGE_SCRIPT_AUTH,
  EXCHANGE_SCRIPT_SWITCH,
  EXCHANGE_SCRIPT_AUTH,		/* Initiator -> responder.  */
  EXCHANGE_SCRIPT_END
};
#endif /* USE_AGGRESSIVE */

int16_t script_informational[] = {
  EXCHANGE_SCRIPT_INFO,		/* Initiator -> responder.  */
  EXCHANGE_SCRIPT_END
};

/*
 * Check what exchange SA is negotiated with and return a suitable validation
 * script.
 */
int16_t *
exchange_script (struct exchange *exchange)
{
  switch (exchange->type)
    {
    case ISAKMP_EXCH_BASE:
      return script_base;
    case ISAKMP_EXCH_ID_PROT:
      return script_identity_protection;
    case ISAKMP_EXCH_AUTH_ONLY:
      return script_authentication_only;
#ifdef USE_AGGRESSIVE
    case ISAKMP_EXCH_AGGRESSIVE:
      return script_aggressive;
#endif
    case ISAKMP_EXCH_INFO:
      return script_informational;
#ifdef USE_ISAKMP_CFG
    case ISAKMP_EXCH_TRANSACTION:
      return script_transaction;
#endif
    default:
      if (exchange->type >= ISAKMP_EXCH_DOI_MIN
	  && exchange->type <= ISAKMP_EXCH_DOI_MAX)
	return exchange->doi->exchange_script (exchange->type);
    }
  return 0;
}

/*
 * Validate the message MSG's contents wrt what payloads the exchange type
 * requires at this point in the dialogoue.  Return -1 if the validation fails,
 * 0 if it succeeds and the script is not finished and 1 if it's ready.
 */
static int
exchange_validate (struct message *msg)
{
  struct exchange *exchange = msg->exchange;
  int16_t *pc = exchange->exch_pc;

  while (*pc != EXCHANGE_SCRIPT_END && *pc != EXCHANGE_SCRIPT_SWITCH)
    {
      LOG_DBG ((LOG_EXCHANGE, 90,
		"exchange_validate: checking for required %s",
		*pc >= ISAKMP_PAYLOAD_NONE
		? constant_name (isakmp_payload_cst, *pc)
		: constant_name (exchange_script_cst, *pc)));

      /* Check for existence of the required payloads.  */
      if ((*pc > 0 && !TAILQ_FIRST (&msg->payload[*pc]))
	  || (*pc == EXCHANGE_SCRIPT_AUTH
	      && !TAILQ_FIRST (&msg->payload[ISAKMP_PAYLOAD_HASH])
	      && !TAILQ_FIRST (&msg->payload[ISAKMP_PAYLOAD_SIG]))
	  || (*pc == EXCHANGE_SCRIPT_INFO
	      && !TAILQ_FIRST (&msg->payload[ISAKMP_PAYLOAD_NOTIFY])
	      && !TAILQ_FIRST (&msg->payload[ISAKMP_PAYLOAD_DELETE])))
	{
	  /* Missing payload.  */
	  LOG_DBG ((LOG_MESSAGE, 70,
		    "exchange_validate: msg %p requires missing %s", msg,
		    *pc >= ISAKMP_PAYLOAD_NONE
		    ? constant_name (isakmp_payload_cst, *pc)
		    : constant_name (exchange_script_cst, *pc)));
	  return -1;
	}
      pc++;
    }
  if (*pc == EXCHANGE_SCRIPT_END)
    /* Cleanup.  */
    return 1;

  return 0;
}

/*
 * Run the exchange script from a point given by the "program counter"
 * upto either the script's end or a transmittal of a message.  If we are
 * at the point of a reception of a message, that message should be handed
 * in here in the MSG argument.  Otherwise we are the initiator and should
 * expect MSG to be a half-cooked message without payloads.
 */
void
exchange_run (struct message *msg)
{
  int i, done = 0;
  struct exchange *exchange = msg->exchange;
  struct doi *doi = exchange->doi;
  int (*handler) (struct message *)
    = exchange->initiator ? doi->initiator : doi->responder;
  struct payload *payload;

  while (!done)
    {
      /*
       * It's our turn if we're either the initiator on an even step,
       * or the responder on an odd step of the dialogue.
       */
      if (exchange->initiator ^ (exchange->step % 2))
	{
	  done = 1;
	  if (exchange->step)
	    msg = message_alloc_reply (msg);
	  message_setup_header (msg, exchange->type, 0, exchange->message_id);
	  if (handler (msg))
	    {
	      /*
	       * This can happen when transient starvation of memory occurs.
	       * XXX The peer's retransmit ought to kick-start this exchange
	       * again.  If he's stopped retransmitting he's likely dropped
	       * the SA at his side so we need to do that too, i.e.
	       * implement automatic SA teardown after a certain amount
	       * of inactivity.
	       */
	      log_print ("exchange_run: doi->%s (%p) failed",
			 exchange->initiator ? "initiator" : "responder", msg);
	      message_free (msg);
	      return;
	    }

	  switch (exchange_validate (msg))
	    {
	    case 1:
	      /*
	       * The last message of a multi-message exchange should
	       * not be retransmitted other than "on-demand", i.e. if we
	       * see retransmits of the last message of the peer
	       * later.
	       */
	      msg->flags |= MSG_LAST;
	      if (exchange->step > 0)
		{
		  if (exchange->last_sent)
		    message_free (exchange->last_sent);
		  exchange->last_sent = msg;
		}

	      /*
	       * After we physically have sent our last message we need to
	       * do SA-specific finalization, like telling our application
	       * the SA is ready to be used, or issuing a CONNECTED notify
	       * if we set the COMMIT bit.
	       */
	      message_register_post_send (msg, exchange_finalize);

	      /* Fallthrough.  */

	    case 0:
	      /* XXX error handling.  */
	      message_send (msg);
	      break;

	    default:
	      log_print ("exchange_run: exchange_validate failed, DOI error");
	      exchange_free (exchange);
	      message_free (msg);
	      return;
	    }
	}
      else
	{
	  done = exchange_validate (msg);
	  switch (done)
	    {
	    case 0:
	    case 1:
	      /* Feed the message to the DOI.  */
	      if (handler (msg))
		{
		  /*
		   * Trust the peer to retransmit.
		   * XXX We have to implement SA aging with automatic teardown.
		   */
		  message_free (msg);
		  return;
		}

	      /*
	       * Go over the yet unhandled payloads and feed them to DOI
	       * for handling.
	       */
	      for (i = ISAKMP_PAYLOAD_SA; i < ISAKMP_PAYLOAD_RESERVED_MIN; i++)
		if (i != ISAKMP_PAYLOAD_PROPOSAL
		    && i != ISAKMP_PAYLOAD_TRANSFORM)
		  for (payload = TAILQ_FIRST (&msg->payload[i]); payload;
		       payload = TAILQ_NEXT (payload, link))
		    if ((payload->flags & PL_MARK) == 0)
		      if (!doi->handle_leftover_payload
			  || doi->handle_leftover_payload (msg, i, payload))
			LOG_DBG ((LOG_EXCHANGE, 10,
				  "exchange_run: unexpected payload %s",
				  constant_name (isakmp_payload_cst, i)));

	      /*
	       * We have advanced the state.  If we have been processing an
	       * incoming message, record that message as the one to do
	       * duplication tests against.
	       */
	      if (exchange->last_received)
		message_free (exchange->last_received);
	      exchange->last_received = msg;
	      if (exchange->flags & EXCHANGE_FLAG_ENCRYPT)
		crypto_update_iv (exchange->keystate);

	      if (done)
		{
		  exchange_finalize (msg);
		  return;
		}
	      break;

	    case -1:
	      log_print ("exchange_run: exchange_validate failed");
	      /* XXX Is this the best error notification type?  */
	      message_drop (msg, ISAKMP_NOTIFY_PAYLOAD_MALFORMED, 0, 1, 1);
	      return;
	    }
	}

      LOG_DBG ((LOG_EXCHANGE, 40,
		"exchange_run: exchange %p finished step %d, advancing...",
		exchange, exchange->step));
      exchange->step++;
      while (*exchange->exch_pc != EXCHANGE_SCRIPT_SWITCH
	     && *exchange->exch_pc != EXCHANGE_SCRIPT_END)
	exchange->exch_pc++;
      exchange->exch_pc++;
    }
}

void
exchange_init ()
{
  int i;

  bucket_mask = (1 << INITIAL_BUCKET_BITS) - 1;
  exchange_tab = malloc ((bucket_mask + 1) * sizeof (struct exchange_list));
  if (!exchange_tab)
    log_fatal ("exchange_init: out of memory");
  for (i = 0; i <= bucket_mask; i++)
    {
      LIST_INIT (&exchange_tab[i]);
    }

}

#if 0
/* XXX Currently unused.  */
static void
exchange_resize (void)
{
  int new_mask = (bucket_mask + 1) * 2 - 1;
  int i;
  struct exchange_list *new_tab;

  new_tab
    = realloc (exchange_tab, (new_mask + 1) * sizeof (struct exchange_list));
  if (!new_tab)
    return;
  for (i = bucket_mask + 1; i <= new_mask; i++)
    {
      LIST_INIT (&new_tab[i]);
    }
  bucket_mask = new_mask;
  /* XXX Rehash existing entries.  */
}
#endif

/* Lookup a phase 1 exchange out of just the initiator cookie.  */
struct exchange *
exchange_lookup_from_icookie (u_int8_t *cookie)
{
  int i;
  struct exchange *exchange;

  for (i = 0; i <= bucket_mask; i++)
    for (exchange = LIST_FIRST (&exchange_tab[i]); exchange;
	 exchange = LIST_NEXT (exchange, link))
      if (memcmp (exchange->cookies, cookie, ISAKMP_HDR_ICOOKIE_LEN) == 0
	  && exchange->phase == 1)
	return exchange;
  return 0;
}

/* Lookup an exchange out of the name and phase.  */
struct exchange *
exchange_lookup_by_name (char *name, int phase)
{
  int i;
  struct exchange *exchange;

  /* If we search for nothing, we will find nothing.  */
  if (!name)
    return 0;

  for (i = 0; i <= bucket_mask; i++)
    for (exchange = LIST_FIRST (&exchange_tab[i]); exchange;
	 exchange = LIST_NEXT (exchange, link))
      {
	LOG_DBG ((LOG_EXCHANGE, 90,
		  "exchange_lookup_by_name: %s == %s && %d == %d?", name,
		  exchange->name ? exchange->name : "<unnamed>", phase,
		  exchange->phase));

	/*
	 * Match by name, but don't select finished exchanges, i.e
	 * where MSG_LAST are set in last_sent msg.
	 */
	if (exchange->name && strcasecmp (exchange->name, name) == 0
	    && exchange->phase == phase
	    && (!exchange->last_sent
		|| (exchange->last_sent->flags & MSG_LAST) == 0))
	  return exchange;
      }
  return 0;
}

/* Lookup an exchange out of the name, phase and step > 1.  */
static struct exchange *
exchange_lookup_active (char *name, int phase)
{
  int i;
  struct exchange *exchange;

  /* XXX Almost identical to exchange_lookup_by_name.  */

  if (!name)
    return 0;

  for (i = 0; i <= bucket_mask; i++)
    for (exchange = LIST_FIRST (&exchange_tab[i]); exchange;
	 exchange = LIST_NEXT (exchange, link))
      {
	LOG_DBG ((LOG_EXCHANGE, 90,
		  "exchange_lookup_active: %s == %s && %d == %d?",
		  name, exchange->name ? exchange->name : "<unnamed>", phase,
		  exchange->phase));
	if (exchange->name && strcasecmp (exchange->name, name) == 0
	    && exchange->phase == phase)
	  {
	    if (exchange->step > 1)
	      return exchange;
	    else
	      LOG_DBG ((LOG_EXCHANGE, 80,
			"exchange_lookup_active: avoided early (pre-step 1) "
			"exchange %p", exchange));
	  }
      }
  return 0;
}

static void
exchange_enter (struct exchange *exchange)
{
  u_int16_t bucket = 0;
  int i;
  u_int8_t *cp;

  /* XXX We might resize if we are crossing a certain threshold */

  for (i = 0; i < ISAKMP_HDR_COOKIES_LEN; i += 2)
    {
      cp = exchange->cookies + i;
      /* Doing it this way avoids alignment problems.  */
      bucket ^= cp[0] | cp[1] << 8;
    }
  for (i = 0; i < ISAKMP_HDR_MESSAGE_ID_LEN; i += 2)
    {
      cp = exchange->message_id + i;
      /* Doing it this way avoids alignment problems.  */
      bucket ^= cp[0] | cp[1] << 8;
    }
  bucket &= bucket_mask;
  LIST_INSERT_HEAD (&exchange_tab[bucket], exchange, link);
}

/*
 * Lookup the exchange given by the header fields MSG.  PHASE2 is false when
 * looking for phase 1 exchanges and true otherwise.
 */
struct exchange *
exchange_lookup (u_int8_t *msg, int phase2)
{
  u_int16_t bucket = 0;
  int i;
  struct exchange *exchange;
  u_int8_t *cp;

  /*
   * We use the cookies to get bits to use as an index into exchange_tab, as at
   * least one (our cookie) is a good hash, xoring all the bits, 16 at a
   * time, and then masking, should do.  Doing it this way means we can
   * validate cookies very fast thus delimiting the effects of "Denial of
   * service"-attacks using packet flooding.
   */
  for (i = 0; i < ISAKMP_HDR_COOKIES_LEN; i += 2)
    {
      cp = msg + ISAKMP_HDR_COOKIES_OFF + i;
      /* Doing it this way avoids alignment problems.  */
      bucket ^= cp[0] | cp[1] << 8;
    }
  if (phase2)
    for (i = 0; i < ISAKMP_HDR_MESSAGE_ID_LEN; i += 2)
      {
	cp = msg + ISAKMP_HDR_MESSAGE_ID_OFF + i;
	/* Doing it this way avoids alignment problems.  */
	bucket ^= cp[0] | cp[1] << 8;
      }
  bucket &= bucket_mask;
  for (exchange = LIST_FIRST (&exchange_tab[bucket]);
       exchange && (memcmp (msg + ISAKMP_HDR_COOKIES_OFF, exchange->cookies,
			    ISAKMP_HDR_COOKIES_LEN) != 0
		    || (phase2 && memcmp (msg + ISAKMP_HDR_MESSAGE_ID_OFF,
					  exchange->message_id,
					  ISAKMP_HDR_MESSAGE_ID_LEN) != 0)
		    || (!phase2 && !zero_test (msg + ISAKMP_HDR_MESSAGE_ID_OFF,
					       ISAKMP_HDR_MESSAGE_ID_LEN)));
       exchange = LIST_NEXT (exchange, link))
    ;

  return exchange;
}

/*
 * Create a phase PHASE exchange where INITIATOR denotes our role.  DOI
 * is the domain of interpretation identifier and TYPE tells what exchange
 * type to use per either the DOI document or the ISAKMP spec proper.
 * NSA tells how many SAs we should pre-allocate, and should be zero
 * when we have the responder role.
 */
static struct exchange *
exchange_create (int phase, int initiator, int doi, int type)
{
  struct exchange *exchange;
  struct timeval expiration;
  int delta;

  /*
   * We want the exchange zeroed for exchange_free to be able to find
   * out what fields have been filled-in.
   */
  exchange = calloc (1, sizeof *exchange);
  if (!exchange)
    {
      log_error ("exchange_create: calloc (1, %lu) failed",
	(unsigned long)sizeof *exchange);
      return 0;
    }
  exchange->phase = phase;
  exchange->step = 0;
  exchange->initiator = initiator;
  memset (exchange->cookies, 0, ISAKMP_HDR_COOKIES_LEN);
  memset (exchange->message_id, 0, ISAKMP_HDR_MESSAGE_ID_LEN);
  exchange->doi = doi_lookup (doi);
  exchange->type = type;
  exchange->policy_id = -1;
  exchange->exch_pc = exchange_script (exchange);
  exchange->last_sent = exchange->last_received = 0;
  TAILQ_INIT (&exchange->sa_list);
  TAILQ_INIT (&exchange->aca_list);

  /* Allocate the DOI-specific structure and initialize it to zeroes.  */
  if (exchange->doi->exchange_size)
    {
      exchange->data = calloc (1, exchange->doi->exchange_size);
      if (!exchange->data)
	{
	  log_error ("exchange_create: calloc (1, %lu) failed",
		(unsigned long)exchange->doi->exchange_size);
	  exchange_free (exchange);
	  return 0;
	}
    }

  gettimeofday (&expiration, 0);
  delta = conf_get_num ("General", "Exchange-max-time", EXCHANGE_MAX_TIME);
  expiration.tv_sec += delta;
  exchange->death = timer_add_event ("exchange_free_aux", exchange_free_aux,
				     exchange, &expiration);
  if (!exchange->death)
    {
      /* If we don't give up we might start leaking...  */
      exchange_free_aux (exchange);
      return 0;
    }

  return exchange;
}

struct exchange_finalization_node
{
  void (*first) (struct exchange *, void *, int);
  void *first_arg;
  void (*second) (struct exchange *, void *, int);
  void *second_arg;
};

/* Run the finalization functions of ARG.  */
static void
exchange_run_finalizations (struct exchange *exchange, void *arg, int fail)
{
  struct exchange_finalization_node *node = arg;

  node->first (exchange, node->first_arg, fail);
  node->second (exchange, node->second_arg, fail);
  free (node);
}

/*
 * Add a finalization function FINALIZE with argument ARG to the tail
 * of the finalization function list of EXCHANGE.
 */
static void
exchange_add_finalization (struct exchange *exchange,
			   void (*finalize) (struct exchange *, void *, int),
			   void *arg)
{
  struct exchange_finalization_node *node;

  if (!finalize)
    return;

  if (!exchange->finalize)
    {
      exchange->finalize = finalize;
      exchange->finalize_arg = arg;
      return;
    }

  node = malloc (sizeof *node);
  if (!node)
    {
      log_error ("exchange_add_finalization: malloc (%lu) failed",
		 (unsigned long)sizeof *node);
      free (arg);
      return;
    }
  node->first = exchange->finalize;
  node->first_arg = exchange->finalize_arg;
  node->second = finalize;
  node->second_arg = arg;
  exchange->finalize = exchange_run_finalizations;
  exchange->finalize_arg = node;
}

static void
exchange_establish_transaction (struct exchange *exchange, void *arg, int fail)
{
  /* Establish a TRANSACTION exchange.  */
  struct exchange_finalization_node *node
    = (struct exchange_finalization_node *)arg;
  struct sa *isakmp_sa = sa_lookup_by_name ((char *)node->second_arg, 1);

  if (isakmp_sa && !fail)
    exchange_establish_p2 (isakmp_sa, ISAKMP_EXCH_TRANSACTION, 0, 0,
			   node->first, node->first_arg);

  free (node);
}

/* Establish a phase 1 exchange.  */
void
exchange_establish_p1 (struct transport *t, u_int8_t type, u_int32_t doi,
		       char *name, void *args,
		       void (*finalize) (struct exchange *, void *, int),
		       void *arg)
{
  struct exchange *exchange;
  struct message *msg;
  struct conf_list *flags;
  struct conf_list_node *flag;
  char *tag = 0;
  char *str;

  if (name)
    {
      /* If no exchange type given, fetch from the configuration.  */
      if (type == 0)
	{
	  /* XXX Similar code can be found in exchange_setup_p1.  Share?  */

	  /* Find out our phase 1 mode.  */
	  tag = conf_get_str (name, "Configuration");
	  if (!tag)
	    {
	      /* Use default setting.  */
	      tag = CONF_DFLT_TAG_PHASE1_CONFIG;
	    }

	  /* Figure out the DOI.  XXX Factor out?  */
	  str = conf_get_str (tag, "DOI");
	  if (!str || strcasecmp (str, "IPSEC") == 0)
	    doi = IPSEC_DOI_IPSEC;
	  else if (strcasecmp (str, "ISAKMP") == 0)
	    doi = ISAKMP_DOI_ISAKMP;
	  else
	    {
	      log_print ("exchange_establish_p1: DOI \"%s\" unsupported", str);
	      return;
	    }

	  /* What exchange type do we want?  */
	  str = conf_get_str (tag, "EXCHANGE_TYPE");
	  if (!str)
	    {
	      log_print ("exchange_establish_p1: "
			 "no \"EXCHANGE_TYPE\" tag in [%s] section", tag);
	      return;
	    }
	  type = constant_value (isakmp_exch_cst, str);
	  if (!type)
	    {
	      log_print ("exchange_establish_p1: unknown exchange type %s",
			 str);
	      return;
	    }
	}
    }

  exchange = exchange_create (1, 1, doi, type);
  if (!exchange)
    {
      /* XXX Do something here?  */
      return;
    }

  if (name)
    {
      exchange->name = strdup (name);
      if (!exchange->name)
	{
	  log_error ("exchange_establish_p1: strdup (\"%s\") failed", name);
	  exchange_free (exchange);
	  return;
	}
    }

  exchange->policy = name ? conf_get_str (name, "Configuration") : 0;
  if (!exchange->policy && name)
    exchange->policy = CONF_DFLT_TAG_PHASE1_CONFIG;

  if (name)
    {
      flags = conf_get_list (name, "Flags");
      if (flags)
	{
	  for (flag = TAILQ_FIRST (&flags->fields); flag;
	       flag = TAILQ_NEXT (flag, link))
	    if (strcasecmp (flag->field, "ikecfg") == 0)
	      {
		struct exchange_finalization_node *node;

		node = calloc (1, (unsigned long)sizeof *node);
		if (!node)
		  {
		    log_print ("exchange_establish_p1: calloc (1, %lu) failed",
			       (unsigned long)sizeof (*node));
		    exchange_free (exchange);
		    return;
		  }

		/* Insert this finalization inbetween the original.  */
		node->first = finalize;
		node->first_arg = arg;
		node->second_arg = name;
		exchange_add_finalization (exchange,
					   exchange_establish_transaction,
					   node);
		finalize = 0;
	      }
	  conf_free_list (flags);
	}
    }
  exchange_add_finalization (exchange, finalize, arg);
  cookie_gen (t, exchange, exchange->cookies, ISAKMP_HDR_ICOOKIE_LEN);
  exchange_enter (exchange);
#ifdef USE_DEBUG
  exchange_dump ("exchange_establish_p1", exchange);
#endif

  msg = message_alloc (t, 0, ISAKMP_HDR_SZ);
  if (!msg)
    {
      log_print ("exchange_establish_p1: message_alloc () failed");
      exchange_free (exchange);
      return;
    }
  msg->exchange = exchange;

  /* Do not create SA for an information or transaction exchange.  */
  if (exchange->type != ISAKMP_EXCH_INFO
      && exchange->type != ISAKMP_EXCH_TRANSACTION)
    {
      /*
       * Don't install a transport into this SA as it will be an INADDR_ANY
       * address in the local end, which is not good at all.  Let the reply
       * packet install the transport instead.
       */
      sa_create (exchange, 0);
      msg->isakmp_sa = TAILQ_FIRST (&exchange->sa_list);
      if (!msg->isakmp_sa)
	{
	  /* XXX Do something more here?  */
	  message_free (msg);
	  exchange_free (exchange);
	  return;
	}
      sa_reference (msg->isakmp_sa);
    }

  msg->extra = args;

  exchange_run (msg);
}

/* Establish a phase 2 exchange.  XXX With just one SA for now.  */
void
exchange_establish_p2 (struct sa *isakmp_sa, u_int8_t type, char *name,
		       void *args,
		       void (*finalize) (struct exchange *, void *, int),
		       void *arg)
{
  struct exchange *exchange;
  struct message *msg;
  int i;
  char *tag, *str;
  u_int32_t doi = ISAKMP_DOI_ISAKMP;
  u_int32_t seq = 0;

  if (isakmp_sa)
    doi = isakmp_sa->doi->id;

  if (name)
    {
      /* Find out our phase 2 modes.  */
      tag = conf_get_str (name, "Configuration");
      if (!tag)
	{
	  log_print ("exchange_establish_p2: no configuration for peer \"%s\"",
		     name);
	  return;
	}

      seq = (u_int32_t) conf_get_num (name, "Acquire-ID", 0);

      /* Figure out the DOI.  */
      str = conf_get_str (tag, "DOI");
      if (!str || strcasecmp (str, "IPSEC") == 0)
	doi = IPSEC_DOI_IPSEC;
      else if (strcasecmp (str, "ISAKMP") == 0)
	doi = ISAKMP_DOI_ISAKMP;
      else
	{
	  log_print ("exchange_establish_p2: DOI \"%s\" unsupported", str);
	  return;
	}

      /* What exchange type do we want?  */
      if (!type)
	{
	  str = conf_get_str (tag, "EXCHANGE_TYPE");
	  if (!str)
	    {
	      log_print ("exchange_establish_p2: "
			 "no \"EXCHANGE_TYPE\" tag in [%s] section", tag);
	      return;
	    }
	  /* XXX IKE dependent.  */
	  type = constant_value (ike_exch_cst, str);
	  if (!type)
	    {
	      log_print ("exchange_establish_p2: unknown exchange type %s",
			 str);
	      return;
	    }
	}
    }

  exchange = exchange_create (2, 1, doi, type);
  if (!exchange)
    {
      /* XXX Do something here?  */
      return;
    }

  if (name)
    {
      exchange->name = strdup (name);
      if (!exchange->name)
	{
	  log_error ("exchange_establish_p2: strdup (\"%s\") failed", name);
	  exchange_free (exchange);
	  return;
	}
    }
  exchange->policy = name ? conf_get_str (name, "Configuration") : 0;
  exchange->finalize = finalize;
  exchange->finalize_arg = arg;
  exchange->seq = seq;
  memcpy (exchange->cookies, isakmp_sa->cookies, ISAKMP_HDR_COOKIES_LEN);
  getrandom (exchange->message_id, ISAKMP_HDR_MESSAGE_ID_LEN);
  exchange->flags |= EXCHANGE_FLAG_ENCRYPT;
  exchange_enter (exchange);
#ifdef USE_DEBUG
  exchange_dump ("exchange_establish_p2", exchange);
#endif

  /*
   * Do not create SA's for informational exchanges.
   * XXX How to handle new group mode?
   */
  if (exchange->type != ISAKMP_EXCH_INFO
      && exchange->type != ISAKMP_EXCH_TRANSACTION)
    {
      /* XXX Number of SAs should come from the args structure.  */
      for (i = 0; i < 1; i++)
	if (sa_create (exchange, isakmp_sa->transport))
	  {
	    exchange_free (exchange);
	    return;
	  }
    }

  msg = message_alloc (isakmp_sa->transport, 0, ISAKMP_HDR_SZ);
  msg->isakmp_sa = isakmp_sa;
  sa_reference (isakmp_sa);

  msg->extra = args;

  /* This needs to be done late or else get_keystate won't work right.  */
  msg->exchange = exchange;

  exchange_run (msg);
}

/* Out of an incoming phase 1 message, setup an exchange.  */
struct exchange *
exchange_setup_p1 (struct message *msg, u_int32_t doi)
{
  struct transport *t = msg->transport;
  struct exchange *exchange;
  struct sockaddr *dst;
  char *name = 0, *policy = 0, *str;
  u_int32_t want_doi;
  u_int8_t type;

  /* XXX Similar code can be found in exchange_establish_p1.  Share?  */

  /*
   * Unless this is an informational exchange, look up our policy for this
   * peer.
   */
  type = GET_ISAKMP_HDR_EXCH_TYPE (msg->iov[0].iov_base);
  if (type != ISAKMP_EXCH_INFO)
    {
      /*
       * Find out our inbound phase 1 mode.
       */
      t->vtbl->get_dst (t, &dst);
      if (sockaddr2text(dst, &str, 0) == -1)
	return 0;
      name = conf_get_str ("Phase 1", str);
      free (str);
      if (name)
	{
	  /*
	   * If another phase 1 exchange is ongoing don't bother returning the
	   * call. However, we will need to continue responding if our phase 1
	   * exchange is still waiting for step 1 (i.e still half-open).
	   */
	  if (exchange_lookup_active (name, 1))
	    return 0;
	}
      else
	{
	  name = conf_get_str ("Phase 1", "Default");
	  if (!name)
	    {
	      log_print ("exchange_setup_p1: "
			 "no \"Default\" tag in [Phase 1] section");
	      return 0;
	    }
	}

      policy = conf_get_str (name, "Configuration");
      if (!policy)
	policy = CONF_DFLT_TAG_PHASE1_CONFIG;

      /* Figure out the DOI.  */
      str = conf_get_str (policy, "DOI");
      if (!str || strcasecmp (str, "IPSEC") == 0)
	want_doi = IPSEC_DOI_IPSEC;
      else if (strcasecmp (str, "ISAKMP") == 0)
	want_doi = ISAKMP_DOI_ISAKMP;
      else
	{
	  log_print ("exchange_setup_p1: DOI \"%s\" unsupported", str);
	  return 0;
	}
      if (want_doi != doi)
	{
	  /* XXX Should I tell what DOI I got?  */
	  log_print ("exchange_setup_p1: expected %s DOI", str);
	  return 0;
	}

      /* What exchange type do we want?  */
      str = conf_get_str (policy, "EXCHANGE_TYPE");
      if (!str)
	{
	  log_print ("exchange_setup_p1: "
		     "no \"EXCHANGE_TYPE\" tag in [%s] section", policy);
	  return 0;
	}
      type = constant_value (isakmp_exch_cst, str);
      if (!type)
	{
	  log_print ("exchange_setup_p1: unknown exchange type %s", str);
	  return 0;
	}
      if (type != GET_ISAKMP_HDR_EXCH_TYPE (msg->iov[0].iov_base))
	{
	  log_print ("exchange_setup_p1: expected exchange type %s got %s",
		     str,
		     constant_lookup (isakmp_exch_cst,
				      GET_ISAKMP_HDR_EXCH_TYPE (msg->iov[0]
								.iov_base)));
	  return 0;
	}
    }

  exchange = exchange_create (1, 0, doi, type);
  if (!exchange)
    return 0;

  exchange->name = name ? strdup (name) : 0;
  if (name && !exchange->name)
    {
      log_error ("exchange_setup_p1: strdup (\"%s\") failed", name);
      exchange_free (exchange);
      return 0;
    }
  exchange->policy = policy;
  cookie_gen (msg->transport, exchange,
	      exchange->cookies + ISAKMP_HDR_ICOOKIE_LEN,
	      ISAKMP_HDR_RCOOKIE_LEN);
  GET_ISAKMP_HDR_ICOOKIE (msg->iov[0].iov_base, exchange->cookies);
  exchange_enter (exchange);
#ifdef USE_DEBUG
  exchange_dump ("exchange_setup_p1", exchange);
#endif
  return exchange;
}

/* Out of an incoming phase 2 message, setup an exchange.  */
struct exchange *
exchange_setup_p2 (struct message *msg, u_int8_t doi)
{
  struct exchange *exchange;
  u_int8_t *buf = msg->iov[0].iov_base;

  exchange = exchange_create (2, 0, doi, GET_ISAKMP_HDR_EXCH_TYPE (buf));
  if (!exchange)
    return 0;
  GET_ISAKMP_HDR_ICOOKIE (buf, exchange->cookies);
  GET_ISAKMP_HDR_RCOOKIE (buf, exchange->cookies + ISAKMP_HDR_ICOOKIE_LEN);
  GET_ISAKMP_HDR_MESSAGE_ID (buf, exchange->message_id);
  exchange_enter (exchange);
#ifdef USE_DEBUG
  exchange_dump ("exchange_setup_p2", exchange);
#endif
  return exchange;
}

/* Dump interesting data about an exchange.  */
static void
exchange_dump_real (char *header, struct exchange *exchange, int class,
		    int level)
{
  char buf[LOG_SIZE];
  /* Don't risk overflowing the final log buffer.  */
  int bufsize_max = LOG_SIZE - strlen (header) - 32;
  struct sa *sa;

  LOG_DBG ((class, level,
	    "%s: %p %s %s policy %s phase %d doi %d exchange %d step %d",
	    header, exchange, exchange->name ? exchange->name : "<unnamed>",
	    exchange->policy ? exchange->policy : "<no policy>",
	    exchange->initiator ? "initiator" : "responder", exchange->phase,
	    exchange->doi->id, exchange->type, exchange->step));
  LOG_DBG ((class, level,
	    "%s: icookie %08x%08x rcookie %08x%08x", header,
	    decode_32 (exchange->cookies), decode_32 (exchange->cookies + 4),
	    decode_32 (exchange->cookies + 8),
	    decode_32 (exchange->cookies + 12)));

  /* Include phase 2 SA list for this exchange */
  if (exchange->phase == 2)
    {
      snprintf (buf, bufsize_max, "sa_list ");
      for (sa = TAILQ_FIRST (&exchange->sa_list);
	   sa && strlen (buf) < bufsize_max; sa = TAILQ_NEXT (sa, next))
	snprintf (buf + strlen (buf), bufsize_max - strlen (buf), "%p ", sa);
      if (sa)
	strlcat (buf, "...", bufsize_max);
    }
  else
    buf[0] = '\0';

  LOG_DBG ((class, level, "%s: msgid %08x %s", header,
	    decode_32 (exchange->message_id), buf));
}

static void
exchange_dump (char *header, struct exchange *exchange)
{
  exchange_dump_real (header, exchange, LOG_EXCHANGE, 10);
}

void
exchange_report (void)
{
  int i;
  struct exchange *exchange;

  for (i = 0; i <= bucket_mask; i++)
    for (exchange = LIST_FIRST (&exchange_tab[i]); exchange;
	 exchange = LIST_NEXT (exchange, link))
      exchange_dump_real ("exchange_report", exchange, LOG_REPORT, 0);
}

/*
 * Release all resources this exchange is using *except* for the "death"
 * event.  When removing an exchange from the expiration handler that event
 * will be dealt with therein instead.
 */
static void
exchange_free_aux (void *v_exch)
{
  struct exchange *exchange = v_exch;
  struct sa *sa, *next_sa;
  struct cert_handler *handler;

  LOG_DBG ((LOG_EXCHANGE, 80, "exchange_free_aux: freeing exchange %p",
	    exchange));

  if (exchange->last_received)
    message_free (exchange->last_received);
  if (exchange->last_sent)
    message_free (exchange->last_sent);
  if (exchange->in_transit && exchange->in_transit != exchange->last_sent)
    message_free (exchange->in_transit);
  if (exchange->nonce_i)
    free (exchange->nonce_i);
  if (exchange->nonce_r)
    free (exchange->nonce_r);
  if (exchange->id_i)
    free (exchange->id_i);
  if (exchange->id_r)
    free (exchange->id_r);
  if (exchange->keystate)
    free (exchange->keystate);
  if (exchange->doi && exchange->doi->free_exchange_data)
    exchange->doi->free_exchange_data (exchange->data);
  if (exchange->data)
    free (exchange->data);
  if (exchange->name)
    free (exchange->name);
  if (exchange->recv_cert)
    {
      handler = cert_get (exchange->recv_certtype);
      if (handler)
	handler->cert_free (exchange->recv_cert);
    }
  if (exchange->sent_cert)
    {
      handler = cert_get (exchange->sent_certtype);
      if (handler)
	handler->cert_free (exchange->sent_cert);
    }
  if (exchange->recv_key)
    key_free (exchange->recv_keytype, ISAKMP_KEYTYPE_PUBLIC,
	      exchange->recv_key);
  if (exchange->sent_key)
    key_free (exchange->sent_keytype, ISAKMP_KEYTYPE_PRIVATE,
	      exchange->sent_key);
  if (exchange->keynote_key)
    free (exchange->keynote_key); /* This is just a string */

#if defined (POLICY) || defined (KEYNOTE)
  if (exchange->policy_id != -1)
    kn_close (exchange->policy_id);
#endif

  exchange_free_aca_list (exchange);
  LIST_REMOVE (exchange, link);

  /* Tell potential finalize routine we never got there.  */
  if (exchange->finalize)
    exchange->finalize (exchange, exchange->finalize_arg, 1);

  /* Remove any SAs that have not been disassociated from us.  */
  for (sa = TAILQ_FIRST (&exchange->sa_list); sa; sa = next_sa)
    {
      next_sa = TAILQ_NEXT (sa, next);
      /* One for the reference in exchange->sa_list.  */
      sa_release (sa);
      /* And two more for the expiration and SA linked list.  */
      sa_free (sa);
    }

  free (exchange);
}

/* Release all resources this exchange is using.  */
void
exchange_free (struct exchange *exchange)
{
  if (exchange->death)
    timer_remove_event (exchange->death);
  exchange_free_aux (exchange);
}

/*
 * Upgrade the phase 1 exchange and its ISAKMP SA with the rcookie of our
 * peer (found in his recently sent message MSG).
 */
void
exchange_upgrade_p1 (struct message *msg)
{
  struct exchange *exchange = msg->exchange;

  LIST_REMOVE (exchange, link);
  GET_ISAKMP_HDR_RCOOKIE (msg->iov[0].iov_base,
			  exchange->cookies + ISAKMP_HDR_ICOOKIE_LEN);
  exchange_enter (exchange);
  sa_isakmp_upgrade (msg);
}

static int
exchange_check_old_sa (struct sa *sa, void *v_arg)
{
  struct sa *new_sa = v_arg;
  char res1[1024];

  if (sa == new_sa || !sa->name || !(sa->flags & SA_FLAG_READY)
      || (sa->flags & SA_FLAG_REPLACED))
    return 0;

  if (sa->phase != new_sa->phase || new_sa->name == 0
      || strcasecmp (sa->name, new_sa->name))
    return 0;

  if (sa->initiator)
    strlcpy (res1, ipsec_decode_ids ("%s %s", sa->id_i, sa->id_i_len, sa->id_r,
				     sa->id_r_len, 0), sizeof res1);
  else
    strlcpy (res1, ipsec_decode_ids ("%s %s", sa->id_r, sa->id_r_len, sa->id_i,
				     sa->id_i_len, 0), sizeof res1);

  LOG_DBG ((LOG_EXCHANGE, 30,
	    "checking whether new SA replaces existing SA with IDs %s", res1));

  if (new_sa->initiator)
    return strcasecmp (res1, ipsec_decode_ids ("%s %s", new_sa->id_i,
					       new_sa->id_i_len, new_sa->id_r,
					       new_sa->id_r_len, 0)) == 0;
  else
    return strcasecmp (res1, ipsec_decode_ids ("%s %s", new_sa->id_r,
					       new_sa->id_r_len, new_sa->id_i,
					       new_sa->id_i_len, 0)) == 0;
}

void
exchange_finalize (struct message *msg)
{
  struct exchange *exchange = msg->exchange;
  struct sa *sa, *old_sa;
  struct proto *proto;
  struct conf_list *attrs;
  struct conf_list_node *attr;
  struct cert_handler *handler;
  int i;

#ifdef USE_DEBUG
  exchange_dump ("exchange_finalize", exchange);
#endif

  /*
   * Walk over all the SAs and noting them as ready.  If we set the
   * COMMIT bit, tell the peer each SA is connected.
   *
   * XXX The decision should really be based on if a SA was installed
   * successfully.
   */
  for (sa = TAILQ_FIRST (&exchange->sa_list); sa; sa = TAILQ_NEXT (sa, next))
    {
      /* Move over the name to the SA.  */
      sa->name = exchange->name ? strdup (exchange->name) : 0;

      if (exchange->flags & EXCHANGE_FLAG_I_COMMITTED)
	{
	  for (proto = TAILQ_FIRST (&sa->protos); proto;
	       proto = TAILQ_NEXT (proto, link))
	    for (i = 0; i < 2; i++)
	      message_send_notification (exchange->last_received,
					 msg->isakmp_sa,
					 ISAKMP_NOTIFY_STATUS_CONNECTED, proto,
					 i);
	}

      /* Locate any old SAs and mark them replaced (SA_FLAG_REPLACED).  */
      while ((old_sa = sa_find (exchange_check_old_sa, sa)) != 0)
	sa_mark_replaced (old_sa);

      /* Setup the SA flags.  */
      sa->flags |= SA_FLAG_READY;
      if (exchange->name)
	{
	  attrs = conf_get_list (exchange->name, "Flags");
	  if (attrs)
	    {
	      for (attr = TAILQ_FIRST (&attrs->fields); attr;
		   attr = TAILQ_NEXT (attr, link))
		sa->flags |= sa_flag (attr->field);
	      conf_free_list (attrs);
	    }
	  /* 'Connections' should stay alive.  */
	  if (connection_exist (exchange->name))
	    {
	      sa->flags |= SA_FLAG_STAYALIVE;

	      /* ISAKMP SA of this connection should also stay alive.  */
	      if (exchange->phase == 2 && msg->isakmp_sa)
		msg->isakmp_sa->flags |= SA_FLAG_STAYALIVE;
	    }
	}

      sa->seq = exchange->seq;
      sa->exch_type = exchange->type;
    }

  /*
   * If this was an phase 1 SA negotiation, save the keystate in the ISAKMP SA
   * structure for future initialization of phase 2 exchanges' keystates.
   * Also save the Phase 1 ID and authentication information.
   */
  if (exchange->phase == 1 && msg->isakmp_sa)
    {
      msg->isakmp_sa->keystate = exchange->keystate;
      exchange->keystate = 0;

      msg->isakmp_sa->recv_certtype = exchange->recv_certtype;
      msg->isakmp_sa->sent_certtype = exchange->sent_certtype;
      msg->isakmp_sa->recv_keytype = exchange->recv_keytype;
      msg->isakmp_sa->sent_keytype = exchange->sent_keytype;
      msg->isakmp_sa->recv_key = exchange->recv_key;
      msg->isakmp_sa->sent_key = exchange->sent_key;
      msg->isakmp_sa->keynote_key = exchange->keynote_key;
      /* Reset.  */
      exchange->recv_key = 0;
      exchange->sent_key = 0;
      exchange->keynote_key = 0;
      msg->isakmp_sa->policy_id = exchange->policy_id;
      exchange->policy_id = -1;
      msg->isakmp_sa->initiator = exchange->initiator;

      if (exchange->recv_certtype && exchange->recv_cert)
	{
	  handler = cert_get (exchange->recv_certtype);
	  if (handler)
	    msg->isakmp_sa->recv_cert
	      = handler->cert_dup (exchange->recv_cert);
	}

      if (exchange->sent_certtype)
        {
	  handler = cert_get (exchange->sent_certtype);
	  if (handler)
	    msg->isakmp_sa->sent_cert
	      = handler->cert_dup (exchange->sent_cert);
	}

      LOG_DBG ((LOG_EXCHANGE, 10,
		"exchange_finalize: phase 1 done: %s, %s",
		!exchange->doi ? "<no doi>" :
		exchange->doi->decode_ids ("initiator id %s, responder id %s",
					   exchange->id_i, exchange->id_i_len,
					   exchange->id_r, exchange->id_r_len,
					   0),
		!msg->isakmp_sa || !msg->isakmp_sa->transport
		? "<no transport>"
		: msg->isakmp_sa->transport->vtbl->decode_ids (msg->isakmp_sa
							       ->transport)));
    }

  /* Copy the ID from phase 1 to exchange or phase 2 SA.  */
  if (msg->isakmp_sa)
    {
      if (exchange->id_i && exchange->id_r)
	{
	  ipsec_clone_id (&msg->isakmp_sa->id_i, &msg->isakmp_sa->id_i_len,
			  exchange->id_i, exchange->id_i_len);
	  ipsec_clone_id (&msg->isakmp_sa->id_r, &msg->isakmp_sa->id_r_len,
			  exchange->id_r, exchange->id_r_len);
	}
      else if (msg->isakmp_sa->id_i && msg->isakmp_sa->id_r)
	{
	  ipsec_clone_id (&exchange->id_i, &exchange->id_i_len,
			  msg->isakmp_sa->id_i, msg->isakmp_sa->id_i_len);
	  ipsec_clone_id (&exchange->id_r, &exchange->id_r_len,
			  msg->isakmp_sa->id_r, msg->isakmp_sa->id_r_len);
	}
    }

  exchange->doi->finalize_exchange (msg);
  if (exchange->finalize)
    exchange->finalize (exchange, exchange->finalize_arg, 0);
  exchange->finalize = 0;

  /*
   * There is no reason to keep the SAs connected to us anymore, in fact
   * it can hurt us if we have short lifetimes on the SAs and we try
   * to call exchange_report, where the SA list will be walked and
   * references to freed SAs can occur.
   */
  while (TAILQ_FIRST (&exchange->sa_list))
    {
      sa = TAILQ_FIRST (&exchange->sa_list);

      if (exchange->id_i && exchange->id_r)
	{
          ipsec_clone_id (&sa->id_i, &sa->id_i_len, exchange->id_i,
		          exchange->id_i_len);
          ipsec_clone_id (&sa->id_r, &sa->id_r_len, exchange->id_r,
		          exchange->id_r_len);
	}

      TAILQ_REMOVE (&exchange->sa_list, sa, next);
      sa_release (sa);
    }

  /* If we have nothing to retransmit we can safely remove ourselves.  */
  if (!exchange->last_sent)
    exchange_free (exchange);
}

/* Stash a nonce into the exchange data.  */
static int
exchange_nonce (struct exchange *exchange, int peer, size_t nonce_sz,
		u_int8_t *buf)
{
  int initiator = exchange->initiator ^ peer;
  u_int8_t **nonce;
  size_t *nonce_len;
  char header[32];

  nonce = initiator ? &exchange->nonce_i : &exchange->nonce_r;
  nonce_len = initiator ? &exchange->nonce_i_len : &exchange->nonce_r_len;
  *nonce_len = nonce_sz;
  *nonce = malloc (nonce_sz);
  if (!*nonce)
    {
      log_error ("exchange_nonce: malloc (%lu) failed", (unsigned long)nonce_sz);
      return -1;
    }
  memcpy (*nonce, buf, nonce_sz);
  snprintf (header, 32, "exchange_nonce: NONCE_%c", initiator ? 'i' : 'r');
  LOG_DBG_BUF ((LOG_EXCHANGE, 80, header, *nonce, nonce_sz));
  return 0;
}

/* Generate our NONCE.  */
int
exchange_gen_nonce (struct message *msg, size_t nonce_sz)
{
  struct exchange *exchange = msg->exchange;
  u_int8_t *buf;

  buf = malloc (ISAKMP_NONCE_SZ + nonce_sz);
  if (!buf)
    {
      log_error ("exchange_gen_nonce: malloc (%lu) failed",
		 ISAKMP_NONCE_SZ + (unsigned long)nonce_sz);
      return -1;
    }
  getrandom (buf + ISAKMP_NONCE_DATA_OFF, nonce_sz);
  if (message_add_payload (msg, ISAKMP_PAYLOAD_NONCE, buf,
			   ISAKMP_NONCE_SZ + nonce_sz, 1))
    {
      free (buf);
      return -1;
    }
  return exchange_nonce (exchange, 0, nonce_sz, buf + ISAKMP_NONCE_DATA_OFF);
}

/* Save the peer's NONCE.  */
int
exchange_save_nonce (struct message *msg)
{
  struct payload *noncep;
  struct exchange *exchange = msg->exchange;

  noncep = TAILQ_FIRST (&msg->payload[ISAKMP_PAYLOAD_NONCE]);
  noncep->flags |= PL_MARK;
  return exchange_nonce (exchange, 1,
			 GET_ISAKMP_GEN_LENGTH (noncep->p)
			 - ISAKMP_NONCE_DATA_OFF,
			 noncep->p + ISAKMP_NONCE_DATA_OFF);
}

/* Save the peer's CERT REQuests.  */
int
exchange_save_certreq (struct message *msg)
{
  struct payload *cp = TAILQ_FIRST (&msg->payload[ISAKMP_PAYLOAD_CERT_REQ]);
  struct exchange *exchange = msg->exchange;
  struct certreq_aca *aca;

  for ( ; cp; cp = TAILQ_NEXT (cp, link))
    {
      cp->flags |= PL_MARK;
      aca = certreq_decode (GET_ISAKMP_CERTREQ_TYPE (cp->p),
			    cp->p + ISAKMP_CERTREQ_AUTHORITY_OFF,
			    GET_ISAKMP_GEN_LENGTH (cp->p) -
			    ISAKMP_CERTREQ_AUTHORITY_OFF);
      if (aca)
	TAILQ_INSERT_TAIL (&exchange->aca_list, aca, link);
    }

  return 0;
}

/* Free the list of pending CERTREQs.  */
void
exchange_free_aca_list (struct exchange *exchange)
{
  struct certreq_aca *aca;

  for (aca = TAILQ_FIRST (&exchange->aca_list); aca;
       aca = TAILQ_FIRST (&exchange->aca_list))
    {
      if (aca->data)
	{
	  if (aca->handler)
	    aca->handler->free_aca (aca->data);
	  free (aca->data);
	}
      TAILQ_REMOVE (&exchange->aca_list, aca, link);
      free (aca);
    }
}

/* Obtain certificates from acceptable certification authority.  */
int
exchange_add_certs (struct message *msg)
{
  struct exchange *exchange = msg->exchange;
  struct certreq_aca *aca;
  u_int8_t *cert;
  u_int32_t certlen;
  u_int8_t *id;
  size_t id_len;

  id = exchange->initiator ? exchange->id_r : exchange->id_i;
  id_len = exchange->initiator ? exchange->id_r_len : exchange->id_i_len;

  /*
   * Without IDs we cannot handle this yet. Keep the aca_list around for 
   * a later step/retry to see if we got the ID by then. 
   * Note: A 'return -1' breaks X509-auth interop in the responder case
   *       with some IPSec clients that send CERTREQs early (ex SSH Sentinel).
   */
  if (!id)
    return 0;

  for (aca = TAILQ_FIRST (&exchange->aca_list); aca;
       aca = TAILQ_NEXT (aca, link))
    {
      /* XXX? If we can not satisfy a CERTREQ we drop the message.  */
      if (!aca->handler->cert_obtain (id, id_len, aca->data, &cert, &certlen))
	{
	  log_print ("exchange_add_certs: could not obtain cert for a type %d "
		     "cert request", aca->id);
	  return -1;
	}
      cert = realloc (cert, ISAKMP_CERT_SZ + certlen);
      if (!cert)
	{
	  log_error ("exchange_add_certs: realloc (%p, %d) failed", cert,
		     ISAKMP_CERT_SZ + certlen);
	  return -1;
	}
      memmove (cert + ISAKMP_CERT_DATA_OFF, cert, certlen);
      SET_ISAKMP_CERT_ENCODING (cert, aca->id);
      if (message_add_payload (msg, ISAKMP_PAYLOAD_CERT, cert,
			       ISAKMP_CERT_SZ + certlen, 1))
	{
	  free (cert);
	  return -1;
	}
    }

  /* We dont need the CERT REQs any more, they are answered.  */
  exchange_free_aca_list (exchange);

  return 0;
}

static void
exchange_establish_finalize (struct exchange *exchange, void *arg, int fail)
{
  char *name = arg;

  LOG_DBG ((LOG_EXCHANGE, 20,
	    "exchange_establish_finalize: "
	    "finalizing exchange %p with arg %p (%s) & fail = %d",
	    exchange, arg, name ? name : "<unnamed>", fail));

  if (!fail)
    exchange_establish (name, 0, 0);
  free (name);
}

/*
 * Establish an exchange named NAME, and record the FINALIZE function
 * taking ARG as an argument to be run after the exchange is ready.
 */
void
exchange_establish (char *name,
		    void (*finalize) (struct exchange *, void *, int),
		    void *arg)
{
  int phase;
  char *trpt;
  struct transport *transport;
  char *peer;
  struct sa *isakmp_sa;
  struct exchange *exchange;
  phase = conf_get_num (name, "Phase", 0);

  /*
   * First of all, never try to establish anything if another exchange of the
   * same kind is running.
   */
  exchange = exchange_lookup_by_name (name, phase);
  if (exchange)
    {
      LOG_DBG ((LOG_EXCHANGE, 40,
		"exchange_establish: %s exchange already exists as %p", name,
		exchange));
      exchange_add_finalization (exchange, finalize, arg);
      return;
    }

  switch (phase)
    {
    case 1:
      trpt = conf_get_str (name, "Transport");
      if (!trpt)
	{
	  /* Phase 1 transport defaults to "udp".  */
	  trpt = ISAKMP_DEFAULT_TRANSPORT;
	}

      transport = transport_create (trpt, name);
      if (!transport)
	{
	  log_print ("exchange_establish: "
		     "transport \"%s\" for peer \"%s\" could not be created",
		     trpt, name);
	  return;
	}

      exchange_establish_p1 (transport, 0, 0, name, 0, finalize, arg);
      break;

    case 2:
      peer = conf_get_str (name, "ISAKMP-peer");
      if (!peer)
	{
	  log_print ("exchange_establish: No ISAKMP-peer given for \"%s\"",
		     name);
	  return;
	}

      isakmp_sa = sa_lookup_by_name (peer, 1);
      if (!isakmp_sa)
	{
	  name = strdup (name);
	  if (!name)
	    {
	      log_error ("exchange_establish: strdup (\"%s\") failed", name);
	      return;
	    }

	  if (conf_get_num (peer, "Phase", 0) != 1)
	    {
	      log_print ("exchange_establish: "
			 "[%s]:ISAKMP-peer's (%s) phase is not 1", name, peer);
	      return;
	    }

	  /*
	   * XXX We're losing information here (what the original finalize
	   * routine was. As a result, if an exchange does not manage to
	   * get through, there may be application-specific information
	   * that won't get cleaned up, since no error signalling will be
	   * done. This is the case with dynamic SAs and PFKEY.
	   */
	  exchange_establish (peer, exchange_establish_finalize, name);
	  exchange = exchange_lookup_by_name (peer, 1);
	  /*
	   * If the exchange was correctly initialized, add the original
	   * finalization routine; otherwise, call it directly.
	   */
	  if (exchange)
	    {
	      exchange_add_finalization (exchange, finalize, arg);
	    }
	  else
	    {
	      finalize (0, arg, 1); /* Indicate failure */
	    }
      return;
	}
      else
	exchange_establish_p2 (isakmp_sa, 0, name, 0, finalize, arg);
      break;

    default:
      log_print ("exchange_establish: "
		 "peer \"%s\" does not have a correct phase (%d)",
		 name, phase);
      break;
    }
}