summaryrefslogtreecommitdiff
path: root/net/sctp/sm_sideeffect.c
blob: 238adf7978e96124f8adef2918b2eab36ba3959c (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
/* SCTP kernel implementation
 * (C) Copyright IBM Corp. 2001, 2004
 * Copyright (c) 1999 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 *
 * This file is part of the SCTP kernel implementation
 *
 * These functions work with the state functions in sctp_sm_statefuns.c
 * to implement that state operations.  These functions implement the
 * steps which require modifying existing data structures.
 *
 * This SCTP implementation is free software;
 * you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This SCTP implementation is distributed in the hope that it
 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 *                 ************************
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU CC; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <lksctp-developers@lists.sourceforge.net>
 *
 * Or submit a bug report through the following website:
 *    http://www.sf.net/projects/lksctp
 *
 * Written or modified by:
 *    La Monte H.P. Yarroll <piggy@acm.org>
 *    Karl Knutson          <karl@athena.chicago.il.us>
 *    Jon Grimm             <jgrimm@austin.ibm.com>
 *    Hui Huang		    <hui.huang@nokia.com>
 *    Dajiang Zhang	    <dajiang.zhang@nokia.com>
 *    Daisy Chang	    <daisyc@us.ibm.com>
 *    Sridhar Samudrala	    <sri@us.ibm.com>
 *    Ardelle Fan	    <ardelle.fan@intel.com>
 *
 * Any bugs reported given to us we will try to fix... any fixes shared will
 * be incorporated into the next SCTP release.
 */

#include <linux/skbuff.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/ip.h>
#include <net/sock.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>

static int sctp_cmd_interpreter(sctp_event_t event_type,
				sctp_subtype_t subtype,
				sctp_state_t state,
				struct sctp_endpoint *ep,
				struct sctp_association *asoc,
				void *event_arg,
				sctp_disposition_t status,
				sctp_cmd_seq_t *commands,
				gfp_t gfp);
static int sctp_side_effects(sctp_event_t event_type, sctp_subtype_t subtype,
			     sctp_state_t state,
			     struct sctp_endpoint *ep,
			     struct sctp_association *asoc,
			     void *event_arg,
			     sctp_disposition_t status,
			     sctp_cmd_seq_t *commands,
			     gfp_t gfp);

/********************************************************************
 * Helper functions
 ********************************************************************/

/* A helper function for delayed processing of INET ECN CE bit. */
static void sctp_do_ecn_ce_work(struct sctp_association *asoc,
				__u32 lowest_tsn)
{
	/* Save the TSN away for comparison when we receive CWR */

	asoc->last_ecne_tsn = lowest_tsn;
	asoc->need_ecne = 1;
}

/* Helper function for delayed processing of SCTP ECNE chunk.  */
/* RFC 2960 Appendix A
 *
 * RFC 2481 details a specific bit for a sender to send in
 * the header of its next outbound TCP segment to indicate to
 * its peer that it has reduced its congestion window.  This
 * is termed the CWR bit.  For SCTP the same indication is made
 * by including the CWR chunk.  This chunk contains one data
 * element, i.e. the TSN number that was sent in the ECNE chunk.
 * This element represents the lowest TSN number in the datagram
 * that was originally marked with the CE bit.
 */
static struct sctp_chunk *sctp_do_ecn_ecne_work(struct sctp_association *asoc,
					   __u32 lowest_tsn,
					   struct sctp_chunk *chunk)
{
	struct sctp_chunk *repl;

	/* Our previously transmitted packet ran into some congestion
	 * so we should take action by reducing cwnd and ssthresh
	 * and then ACK our peer that we we've done so by
	 * sending a CWR.
	 */

	/* First, try to determine if we want to actually lower
	 * our cwnd variables.  Only lower them if the ECNE looks more
	 * recent than the last response.
	 */
	if (TSN_lt(asoc->last_cwr_tsn, lowest_tsn)) {
		struct sctp_transport *transport;

		/* Find which transport's congestion variables
		 * need to be adjusted.
		 */
		transport = sctp_assoc_lookup_tsn(asoc, lowest_tsn);

		/* Update the congestion variables. */
		if (transport)
			sctp_transport_lower_cwnd(transport,
						  SCTP_LOWER_CWND_ECNE);
		asoc->last_cwr_tsn = lowest_tsn;
	}

	/* Always try to quiet the other end.  In case of lost CWR,
	 * resend last_cwr_tsn.
	 */
	repl = sctp_make_cwr(asoc, asoc->last_cwr_tsn, chunk);

	/* If we run out of memory, it will look like a lost CWR.  We'll
	 * get back in sync eventually.
	 */
	return repl;
}

/* Helper function to do delayed processing of ECN CWR chunk.  */
static void sctp_do_ecn_cwr_work(struct sctp_association *asoc,
				 __u32 lowest_tsn)
{
	/* Turn off ECNE getting auto-prepended to every outgoing
	 * packet
	 */
	asoc->need_ecne = 0;
}

/* Generate SACK if necessary.  We call this at the end of a packet.  */
static int sctp_gen_sack(struct sctp_association *asoc, int force,
			 sctp_cmd_seq_t *commands)
{
	__u32 ctsn, max_tsn_seen;
	struct sctp_chunk *sack;
	struct sctp_transport *trans = asoc->peer.last_data_from;
	int error = 0;

	if (force ||
	    (!trans && (asoc->param_flags & SPP_SACKDELAY_DISABLE)) ||
	    (trans && (trans->param_flags & SPP_SACKDELAY_DISABLE)))
		asoc->peer.sack_needed = 1;

	ctsn = sctp_tsnmap_get_ctsn(&asoc->peer.tsn_map);
	max_tsn_seen = sctp_tsnmap_get_max_tsn_seen(&asoc->peer.tsn_map);

	/* From 12.2 Parameters necessary per association (i.e. the TCB):
	 *
	 * Ack State : This flag indicates if the next received packet
	 * 	     : is to be responded to with a SACK. ...
	 *	     : When DATA chunks are out of order, SACK's
	 *           : are not delayed (see Section 6).
	 *
	 * [This is actually not mentioned in Section 6, but we
	 * implement it here anyway. --piggy]
	 */
	if (max_tsn_seen != ctsn)
		asoc->peer.sack_needed = 1;

	/* From 6.2  Acknowledgement on Reception of DATA Chunks:
	 *
	 * Section 4.2 of [RFC2581] SHOULD be followed. Specifically,
	 * an acknowledgement SHOULD be generated for at least every
	 * second packet (not every second DATA chunk) received, and
	 * SHOULD be generated within 200 ms of the arrival of any
	 * unacknowledged DATA chunk. ...
	 */
	if (!asoc->peer.sack_needed) {
		asoc->peer.sack_cnt++;

		/* Set the SACK delay timeout based on the
		 * SACK delay for the last transport
		 * data was received from, or the default
		 * for the association.
		 */
		if (trans) {
			/* We will need a SACK for the next packet.  */
			if (asoc->peer.sack_cnt >= trans->sackfreq - 1)
				asoc->peer.sack_needed = 1;

			asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] =
				trans->sackdelay;
		} else {
			/* We will need a SACK for the next packet.  */
			if (asoc->peer.sack_cnt >= asoc->sackfreq - 1)
				asoc->peer.sack_needed = 1;

			asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] =
				asoc->sackdelay;
		}

		/* Restart the SACK timer. */
		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
				SCTP_TO(SCTP_EVENT_TIMEOUT_SACK));
	} else {
		if (asoc->a_rwnd > asoc->rwnd)
			asoc->a_rwnd = asoc->rwnd;
		sack = sctp_make_sack(asoc);
		if (!sack)
			goto nomem;

		asoc->peer.sack_needed = 0;
		asoc->peer.sack_cnt = 0;

		sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(sack));

		/* Stop the SACK timer.  */
		sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_STOP,
				SCTP_TO(SCTP_EVENT_TIMEOUT_SACK));
	}

	return error;
nomem:
	error = -ENOMEM;
	return error;
}

/* When the T3-RTX timer expires, it calls this function to create the
 * relevant state machine event.
 */
void sctp_generate_t3_rtx_event(unsigned long peer)
{
	int error;
	struct sctp_transport *transport = (struct sctp_transport *) peer;
	struct sctp_association *asoc = transport->asoc;

	/* Check whether a task is in the sock.  */

	sctp_bh_lock_sock(asoc->base.sk);
	if (sock_owned_by_user(asoc->base.sk)) {
		SCTP_DEBUG_PRINTK("%s:Sock is busy.\n", __func__);

		/* Try again later.  */
		if (!mod_timer(&transport->T3_rtx_timer, jiffies + (HZ/20)))
			sctp_transport_hold(transport);
		goto out_unlock;
	}

	/* Is this transport really dead and just waiting around for
	 * the timer to let go of the reference?
	 */
	if (transport->dead)
		goto out_unlock;

	/* Run through the state machine.  */
	error = sctp_do_sm(SCTP_EVENT_T_TIMEOUT,
			   SCTP_ST_TIMEOUT(SCTP_EVENT_TIMEOUT_T3_RTX),
			   asoc->state,
			   asoc->ep, asoc,
			   transport, GFP_ATOMIC);

	if (error)
		asoc->base.sk->sk_err = -error;

out_unlock:
	sctp_bh_unlock_sock(asoc->base.sk);
	sctp_transport_put(transport);
}

/* This is a sa interface for producing timeout events.  It works
 * for timeouts which use the association as their parameter.
 */
static void sctp_generate_timeout_event(struct sctp_association *asoc,
					sctp_event_timeout_t timeout_type)
{
	int error = 0;

	sctp_bh_lock_sock(asoc->base.sk);
	if (sock_owned_by_user(asoc->base.sk)) {
		SCTP_DEBUG_PRINTK("%s:Sock is busy: timer %d\n",
				  __func__,
				  timeout_type);

		/* Try again later.  */
		if (!mod_timer(&asoc->timers[timeout_type], jiffies + (HZ/20)))
			sctp_association_hold(asoc);
		goto out_unlock;
	}

	/* Is this association really dead and just waiting around for
	 * the timer to let go of the reference?
	 */
	if (asoc->base.dead)
		goto out_unlock;

	/* Run through the state machine.  */
	error = sctp_do_sm(SCTP_EVENT_T_TIMEOUT,
			   SCTP_ST_TIMEOUT(timeout_type),
			   asoc->state, asoc->ep, asoc,
			   (void *)timeout_type, GFP_ATOMIC);

	if (error)
		asoc->base.sk->sk_err = -error;

out_unlock:
	sctp_bh_unlock_sock(asoc->base.sk);
	sctp_association_put(asoc);
}

static void sctp_generate_t1_cookie_event(unsigned long data)
{
	struct sctp_association *asoc = (struct sctp_association *) data;
	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T1_COOKIE);
}

static void sctp_generate_t1_init_event(unsigned long data)
{
	struct sctp_association *asoc = (struct sctp_association *) data;
	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T1_INIT);
}

static void sctp_generate_t2_shutdown_event(unsigned long data)
{
	struct sctp_association *asoc = (struct sctp_association *) data;
	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T2_SHUTDOWN);
}

static void sctp_generate_t4_rto_event(unsigned long data)
{
	struct sctp_association *asoc = (struct sctp_association *) data;
	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_T4_RTO);
}

static void sctp_generate_t5_shutdown_guard_event(unsigned long data)
{
	struct sctp_association *asoc = (struct sctp_association *)data;
	sctp_generate_timeout_event(asoc,
				    SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD);

} /* sctp_generate_t5_shutdown_guard_event() */

static void sctp_generate_autoclose_event(unsigned long data)
{
	struct sctp_association *asoc = (struct sctp_association *) data;
	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_AUTOCLOSE);
}

/* Generate a heart beat event.  If the sock is busy, reschedule.   Make
 * sure that the transport is still valid.
 */
void sctp_generate_heartbeat_event(unsigned long data)
{
	int error = 0;
	struct sctp_transport *transport = (struct sctp_transport *) data;
	struct sctp_association *asoc = transport->asoc;

	sctp_bh_lock_sock(asoc->base.sk);
	if (sock_owned_by_user(asoc->base.sk)) {
		SCTP_DEBUG_PRINTK("%s:Sock is busy.\n", __func__);

		/* Try again later.  */
		if (!mod_timer(&transport->hb_timer, jiffies + (HZ/20)))
			sctp_transport_hold(transport);
		goto out_unlock;
	}

	/* Is this structure just waiting around for us to actually
	 * get destroyed?
	 */
	if (transport->dead)
		goto out_unlock;

	error = sctp_do_sm(SCTP_EVENT_T_TIMEOUT,
			   SCTP_ST_TIMEOUT(SCTP_EVENT_TIMEOUT_HEARTBEAT),
			   asoc->state, asoc->ep, asoc,
			   transport, GFP_ATOMIC);

	 if (error)
		 asoc->base.sk->sk_err = -error;

out_unlock:
	sctp_bh_unlock_sock(asoc->base.sk);
	sctp_transport_put(transport);
}

/* Inject a SACK Timeout event into the state machine.  */
static void sctp_generate_sack_event(unsigned long data)
{
	struct sctp_association *asoc = (struct sctp_association *) data;
	sctp_generate_timeout_event(asoc, SCTP_EVENT_TIMEOUT_SACK);
}

sctp_timer_event_t *sctp_timer_events[SCTP_NUM_TIMEOUT_TYPES] = {
	NULL,
	sctp_generate_t1_cookie_event,
	sctp_generate_t1_init_event,
	sctp_generate_t2_shutdown_event,
	NULL,
	sctp_generate_t4_rto_event,
	sctp_generate_t5_shutdown_guard_event,
	NULL,
	sctp_generate_sack_event,
	sctp_generate_autoclose_event,
};


/* RFC 2960 8.2 Path Failure Detection
 *
 * When its peer endpoint is multi-homed, an endpoint should keep a
 * error counter for each of the destination transport addresses of the
 * peer endpoint.
 *
 * Each time the T3-rtx timer expires on any address, or when a
 * HEARTBEAT sent to an idle address is not acknowledged within a RTO,
 * the error counter of that destination address will be incremented.
 * When the value in the error counter exceeds the protocol parameter
 * 'Path.Max.Retrans' of that destination address, the endpoint should
 * mark the destination transport address as inactive, and a
 * notification SHOULD be sent to the upper layer.
 *
 */
static void sctp_do_8_2_transport_strike(struct sctp_association *asoc,
					 struct sctp_transport *transport,
					 int is_hb)
{
	/* The check for association's overall error counter exceeding the
	 * threshold is done in the state function.
	 */
	/* When probing UNCONFIRMED addresses, the association overall
	 * error count is NOT incremented
	 */
	if (transport->state != SCTP_UNCONFIRMED)
		asoc->overall_error_count++;

	if (transport->state != SCTP_INACTIVE &&
	    (transport->error_count++ >= transport->pathmaxrxt)) {
		SCTP_DEBUG_PRINTK_IPADDR("transport_strike:association %p",
					 " transport IP: port:%d failed.\n",
					 asoc,
					 (&transport->ipaddr),
					 ntohs(transport->ipaddr.v4.sin_port));
		sctp_assoc_control_transport(asoc, transport,
					     SCTP_TRANSPORT_DOWN,
					     SCTP_FAILED_THRESHOLD);
	}

	/* E2) For the destination address for which the timer
	 * expires, set RTO <- RTO * 2 ("back off the timer").  The
	 * maximum value discussed in rule C7 above (RTO.max) may be
	 * used to provide an upper bound to this doubling operation.
	 *
	 * Special Case:  the first HB doesn't trigger exponential backoff.
	 * The first unacknowleged HB triggers it.  We do this with a flag
	 * that indicates that we have an outstanding HB.
	 */
	if (!is_hb || transport->hb_sent) {
		transport->last_rto = transport->rto;
		transport->rto = min((transport->rto * 2), transport->asoc->rto_max);
	}
}

/* Worker routine to handle INIT command failure.  */
static void sctp_cmd_init_failed(sctp_cmd_seq_t *commands,
				 struct sctp_association *asoc,
				 unsigned error)
{
	struct sctp_ulpevent *event;

	event = sctp_ulpevent_make_assoc_change(asoc,0, SCTP_CANT_STR_ASSOC,
						(__u16)error, 0, 0, NULL,
						GFP_ATOMIC);

	if (event)
		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
				SCTP_ULPEVENT(event));

	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
			SCTP_STATE(SCTP_STATE_CLOSED));

	/* SEND_FAILED sent later when cleaning up the association. */
	asoc->outqueue.error = error;
	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
}

/* Worker routine to handle SCTP_CMD_ASSOC_FAILED.  */
static void sctp_cmd_assoc_failed(sctp_cmd_seq_t *commands,
				  struct sctp_association *asoc,
				  sctp_event_t event_type,
				  sctp_subtype_t subtype,
				  struct sctp_chunk *chunk,
				  unsigned error)
{
	struct sctp_ulpevent *event;

	/* Cancel any partial delivery in progress. */
	sctp_ulpq_abort_pd(&asoc->ulpq, GFP_ATOMIC);

	if (event_type == SCTP_EVENT_T_CHUNK && subtype.chunk == SCTP_CID_ABORT)
		event = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_LOST,
						(__u16)error, 0, 0, chunk,
						GFP_ATOMIC);
	else
		event = sctp_ulpevent_make_assoc_change(asoc, 0, SCTP_COMM_LOST,
						(__u16)error, 0, 0, NULL,
						GFP_ATOMIC);
	if (event)
		sctp_add_cmd_sf(commands, SCTP_CMD_EVENT_ULP,
				SCTP_ULPEVENT(event));

	sctp_add_cmd_sf(commands, SCTP_CMD_NEW_STATE,
			SCTP_STATE(SCTP_STATE_CLOSED));

	/* SEND_FAILED sent later when cleaning up the association. */
	asoc->outqueue.error = error;
	sctp_add_cmd_sf(commands, SCTP_CMD_DELETE_TCB, SCTP_NULL());
}

/* Process an init chunk (may be real INIT/INIT-ACK or an embedded INIT
 * inside the cookie.  In reality, this is only used for INIT-ACK processing
 * since all other cases use "temporary" associations and can do all
 * their work in statefuns directly.
 */
static int sctp_cmd_process_init(sctp_cmd_seq_t *commands,
				 struct sctp_association *asoc,
				 struct sctp_chunk *chunk,
				 sctp_init_chunk_t *peer_init,
				 gfp_t gfp)
{
	int error;

	/* We only process the init as a sideeffect in a single
	 * case.   This is when we process the INIT-ACK.   If we
	 * fail during INIT processing (due to malloc problems),
	 * just return the error and stop processing the stack.
	 */
	if (!sctp_process_init(asoc, chunk->chunk_hdr->type,
			       sctp_source(chunk), peer_init, gfp))
		error = -ENOMEM;
	else
		error = 0;

	return error;
}

/* Helper function to break out starting up of heartbeat timers.  */
static void sctp_cmd_hb_timers_start(sctp_cmd_seq_t *cmds,
				     struct sctp_association *asoc)
{
	struct sctp_transport *t;

	/* Start a heartbeat timer for each transport on the association.
	 * hold a reference on the transport to make sure none of
	 * the needed data structures go away.
	 */
	list_for_each_entry(t, &asoc->peer.transport_addr_list, transports) {

		if (!mod_timer(&t->hb_timer, sctp_transport_timeout(t)))
			sctp_transport_hold(t);
	}
}

static void sctp_cmd_hb_timers_stop(sctp_cmd_seq_t *cmds,
				    struct sctp_association *asoc)
{
	struct sctp_transport *t;

	/* Stop all heartbeat timers. */

	list_for_each_entry(t, &asoc->peer.transport_addr_list,
			transports) {
		if (del_timer(&t->hb_timer))
			sctp_transport_put(t);
	}
}

/* Helper function to stop any pending T3-RTX timers */
static void sctp_cmd_t3_rtx_timers_stop(sctp_cmd_seq_t *cmds,
					struct sctp_association *asoc)
{
	struct sctp_transport *t;

	list_for_each_entry(t, &asoc->peer.transport_addr_list,
			transports) {
		if (timer_pending(&t->T3_rtx_timer) &&
		    del_timer(&t->T3_rtx_timer)) {
			sctp_transport_put(t);
		}
	}
}


/* Helper function to update the heartbeat timer. */
static void sctp_cmd_hb_timer_update(sctp_cmd_seq_t *cmds,
				     struct sctp_transport *t)
{
	/* Update the heartbeat timer.  */
	if (!mod_timer(&t->hb_timer, sctp_transport_timeout(t)))
		sctp_transport_hold(t);
}

/* Helper function to handle the reception of an HEARTBEAT ACK.  */
static void sctp_cmd_transport_on(sctp_cmd_seq_t *cmds,
				  struct sctp_association *asoc,
				  struct sctp_transport *t,
				  struct sctp_chunk *chunk)
{
	sctp_sender_hb_info_t *hbinfo;

	/* 8.3 Upon the receipt of the HEARTBEAT ACK, the sender of the
	 * HEARTBEAT should clear the error counter of the destination
	 * transport address to which the HEARTBEAT was sent.
	 * The association's overall error count is also cleared.
	 */
	t->error_count = 0;
	t->asoc->overall_error_count = 0;

	/* Clear the hb_sent flag to signal that we had a good
	 * acknowledgement.
	 */
	t->hb_sent = 0;

	/* Mark the destination transport address as active if it is not so
	 * marked.
	 */
	if ((t->state == SCTP_INACTIVE) || (t->state == SCTP_UNCONFIRMED))
		sctp_assoc_control_transport(asoc, t, SCTP_TRANSPORT_UP,
					     SCTP_HEARTBEAT_SUCCESS);

	/* The receiver of the HEARTBEAT ACK should also perform an
	 * RTT measurement for that destination transport address
	 * using the time value carried in the HEARTBEAT ACK chunk.
	 * If the transport's rto_pending variable has been cleared,
	 * it was most likely due to a retransmit.  However, we want
	 * to re-enable it to properly update the rto.
	 */
	if (t->rto_pending == 0)
		t->rto_pending = 1;

	hbinfo = (sctp_sender_hb_info_t *) chunk->skb->data;
	sctp_transport_update_rto(t, (jiffies - hbinfo->sent_at));

	/* Update the heartbeat timer.  */
	if (!mod_timer(&t->hb_timer, sctp_transport_timeout(t)))
		sctp_transport_hold(t);
}


/* Helper function to process the process SACK command.  */
static int sctp_cmd_process_sack(sctp_cmd_seq_t *cmds,
				 struct sctp_association *asoc,
				 struct sctp_sackhdr *sackh)
{
	int err = 0;

	if (sctp_outq_sack(&asoc->outqueue, sackh)) {
		/* There are no more TSNs awaiting SACK.  */
		err = sctp_do_sm(SCTP_EVENT_T_OTHER,
				 SCTP_ST_OTHER(SCTP_EVENT_NO_PENDING_TSN),
				 asoc->state, asoc->ep, asoc, NULL,
				 GFP_ATOMIC);
	}

	return err;
}

/* Helper function to set the timeout value for T2-SHUTDOWN timer and to set
 * the transport for a shutdown chunk.
 */
static void sctp_cmd_setup_t2(sctp_cmd_seq_t *cmds,
			      struct sctp_association *asoc,
			      struct sctp_chunk *chunk)
{
	struct sctp_transport *t;

	t = sctp_assoc_choose_alter_transport(asoc,
					      asoc->shutdown_last_sent_to);
	asoc->shutdown_last_sent_to = t;
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = t->rto;
	chunk->transport = t;
}

/* Helper function to change the state of an association. */
static void sctp_cmd_new_state(sctp_cmd_seq_t *cmds,
			       struct sctp_association *asoc,
			       sctp_state_t state)
{
	struct sock *sk = asoc->base.sk;

	asoc->state = state;

	SCTP_DEBUG_PRINTK("sctp_cmd_new_state: asoc %p[%s]\n",
			  asoc, sctp_state_tbl[state]);

	if (sctp_style(sk, TCP)) {
		/* Change the sk->sk_state of a TCP-style socket that has
		 * sucessfully completed a connect() call.
		 */
		if (sctp_state(asoc, ESTABLISHED) && sctp_sstate(sk, CLOSED))
			sk->sk_state = SCTP_SS_ESTABLISHED;

		/* Set the RCV_SHUTDOWN flag when a SHUTDOWN is received. */
		if (sctp_state(asoc, SHUTDOWN_RECEIVED) &&
		    sctp_sstate(sk, ESTABLISHED))
			sk->sk_shutdown |= RCV_SHUTDOWN;
	}

	if (sctp_state(asoc, COOKIE_WAIT)) {
		/* Reset init timeouts since they may have been
		 * increased due to timer expirations.
		 */
		asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] =
						asoc->rto_initial;
		asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] =
						asoc->rto_initial;
	}

	if (sctp_state(asoc, ESTABLISHED) ||
	    sctp_state(asoc, CLOSED) ||
	    sctp_state(asoc, SHUTDOWN_RECEIVED)) {
		/* Wake up any processes waiting in the asoc's wait queue in
		 * sctp_wait_for_connect() or sctp_wait_for_sndbuf().
		 */
		if (waitqueue_active(&asoc->wait))
			wake_up_interruptible(&asoc->wait);

		/* Wake up any processes waiting in the sk's sleep queue of
		 * a TCP-style or UDP-style peeled-off socket in
		 * sctp_wait_for_accept() or sctp_wait_for_packet().
		 * For a UDP-style socket, the waiters are woken up by the
		 * notifications.
		 */
		if (!sctp_style(sk, UDP))
			sk->sk_state_change(sk);
	}
}

/* Helper function to delete an association. */
static void sctp_cmd_delete_tcb(sctp_cmd_seq_t *cmds,
				struct sctp_association *asoc)
{
	struct sock *sk = asoc->base.sk;

	/* If it is a non-temporary association belonging to a TCP-style
	 * listening socket that is not closed, do not free it so that accept()
	 * can pick it up later.
	 */
	if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING) &&
	    (!asoc->temp) && (sk->sk_shutdown != SHUTDOWN_MASK))
		return;

	sctp_unhash_established(asoc);
	sctp_association_free(asoc);
}

/*
 * ADDIP Section 4.1 ASCONF Chunk Procedures
 * A4) Start a T-4 RTO timer, using the RTO value of the selected
 * destination address (we use active path instead of primary path just
 * because primary path may be inactive.
 */
static void sctp_cmd_setup_t4(sctp_cmd_seq_t *cmds,
				struct sctp_association *asoc,
				struct sctp_chunk *chunk)
{
	struct sctp_transport *t;

	t = sctp_assoc_choose_alter_transport(asoc, chunk->transport);
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T4_RTO] = t->rto;
	chunk->transport = t;
}

/* Process an incoming Operation Error Chunk. */
static void sctp_cmd_process_operr(sctp_cmd_seq_t *cmds,
				   struct sctp_association *asoc,
				   struct sctp_chunk *chunk)
{
	struct sctp_errhdr *err_hdr;
	struct sctp_ulpevent *ev;

	while (chunk->chunk_end > chunk->skb->data) {
		err_hdr = (struct sctp_errhdr *)(chunk->skb->data);

		ev = sctp_ulpevent_make_remote_error(asoc, chunk, 0,
						     GFP_ATOMIC);
		if (!ev)
			return;

		sctp_ulpq_tail_event(&asoc->ulpq, ev);

		switch (err_hdr->cause) {
		case SCTP_ERROR_UNKNOWN_CHUNK:
		{
			sctp_chunkhdr_t *unk_chunk_hdr;

			unk_chunk_hdr = (sctp_chunkhdr_t *)err_hdr->variable;
			switch (unk_chunk_hdr->type) {
			/* ADDIP 4.1 A9) If the peer responds to an ASCONF with
			 * an ERROR chunk reporting that it did not recognized
			 * the ASCONF chunk type, the sender of the ASCONF MUST
			 * NOT send any further ASCONF chunks and MUST stop its
			 * T-4 timer.
			 */
			case SCTP_CID_ASCONF:
				if (asoc->peer.asconf_capable == 0)
					break;

				asoc->peer.asconf_capable = 0;
				sctp_add_cmd_sf(cmds, SCTP_CMD_TIMER_STOP,
					SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
				break;
			default:
				break;
			}
			break;
		}
		default:
			break;
		}
	}
}

/* Process variable FWDTSN chunk information. */
static void sctp_cmd_process_fwdtsn(struct sctp_ulpq *ulpq,
				    struct sctp_chunk *chunk)
{
	struct sctp_fwdtsn_skip *skip;
	/* Walk through all the skipped SSNs */
	sctp_walk_fwdtsn(skip, chunk) {
		sctp_ulpq_skip(ulpq, ntohs(skip->stream), ntohs(skip->ssn));
	}

	return;
}

/* Helper function to remove the association non-primary peer
 * transports.
 */
static void sctp_cmd_del_non_primary(struct sctp_association *asoc)
{
	struct sctp_transport *t;
	struct list_head *pos;
	struct list_head *temp;

	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
		t = list_entry(pos, struct sctp_transport, transports);
		if (!sctp_cmp_addr_exact(&t->ipaddr,
					 &asoc->peer.primary_addr)) {
			sctp_assoc_del_peer(asoc, &t->ipaddr);
		}
	}

	return;
}

/* Helper function to set sk_err on a 1-1 style socket. */
static void sctp_cmd_set_sk_err(struct sctp_association *asoc, int error)
{
	struct sock *sk = asoc->base.sk;

	if (!sctp_style(sk, UDP))
		sk->sk_err = error;
}

/* Helper function to generate an association change event */
static void sctp_cmd_assoc_change(sctp_cmd_seq_t *commands,
				 struct sctp_association *asoc,
				 u8 state)
{
	struct sctp_ulpevent *ev;

	ev = sctp_ulpevent_make_assoc_change(asoc, 0, state, 0,
					    asoc->c.sinit_num_ostreams,
					    asoc->c.sinit_max_instreams,
					    NULL, GFP_ATOMIC);
	if (ev)
		sctp_ulpq_tail_event(&asoc->ulpq, ev);
}

/* Helper function to generate an adaptation indication event */
static void sctp_cmd_adaptation_ind(sctp_cmd_seq_t *commands,
				    struct sctp_association *asoc)
{
	struct sctp_ulpevent *ev;

	ev = sctp_ulpevent_make_adaptation_indication(asoc, GFP_ATOMIC);

	if (ev)
		sctp_ulpq_tail_event(&asoc->ulpq, ev);
}


static void sctp_cmd_t1_timer_update(struct sctp_association *asoc,
				    sctp_event_timeout_t timer,
				    char *name)
{
	struct sctp_transport *t;

	t = asoc->init_last_sent_to;
	asoc->init_err_counter++;

	if (t->init_sent_count > (asoc->init_cycle + 1)) {
		asoc->timeouts[timer] *= 2;
		if (asoc->timeouts[timer] > asoc->max_init_timeo) {
			asoc->timeouts[timer] = asoc->max_init_timeo;
		}
		asoc->init_cycle++;
		SCTP_DEBUG_PRINTK(
			"T1 %s Timeout adjustment"
			" init_err_counter: %d"
			" cycle: %d"
			" timeout: %ld\n",
			name,
			asoc->init_err_counter,
			asoc->init_cycle,
			asoc->timeouts[timer]);
	}

}

/* Send the whole message, chunk by chunk, to the outqueue.
 * This way the whole message is queued up and bundling if
 * encouraged for small fragments.
 */
static int sctp_cmd_send_msg(struct sctp_association *asoc,
				struct sctp_datamsg *msg)
{
	struct sctp_chunk *chunk;
	int error = 0;

	list_for_each_entry(chunk, &msg->chunks, frag_list) {
		error = sctp_outq_tail(&asoc->outqueue, chunk);
		if (error)
			break;
	}

	return error;
}



/* These three macros allow us to pull the debugging code out of the
 * main flow of sctp_do_sm() to keep attention focused on the real
 * functionality there.
 */
#define DEBUG_PRE \
	SCTP_DEBUG_PRINTK("sctp_do_sm prefn: " \
			  "ep %p, %s, %s, asoc %p[%s], %s\n", \
			  ep, sctp_evttype_tbl[event_type], \
			  (*debug_fn)(subtype), asoc, \
			  sctp_state_tbl[state], state_fn->name)

#define DEBUG_POST \
	SCTP_DEBUG_PRINTK("sctp_do_sm postfn: " \
			  "asoc %p, status: %s\n", \
			  asoc, sctp_status_tbl[status])

#define DEBUG_POST_SFX \
	SCTP_DEBUG_PRINTK("sctp_do_sm post sfx: error %d, asoc %p[%s]\n", \
			  error, asoc, \
			  sctp_state_tbl[(asoc && sctp_id2assoc(ep->base.sk, \
			  sctp_assoc2id(asoc)))?asoc->state:SCTP_STATE_CLOSED])

/*
 * This is the master state machine processing function.
 *
 * If you want to understand all of lksctp, this is a
 * good place to start.
 */
int sctp_do_sm(sctp_event_t event_type, sctp_subtype_t subtype,
	       sctp_state_t state,
	       struct sctp_endpoint *ep,
	       struct sctp_association *asoc,
	       void *event_arg,
	       gfp_t gfp)
{
	sctp_cmd_seq_t commands;
	const sctp_sm_table_entry_t *state_fn;
	sctp_disposition_t status;
	int error = 0;
	typedef const char *(printfn_t)(sctp_subtype_t);

	static printfn_t *table[] = {
		NULL, sctp_cname, sctp_tname, sctp_oname, sctp_pname,
	};
	printfn_t *debug_fn  __attribute__ ((unused)) = table[event_type];

	/* Look up the state function, run it, and then process the
	 * side effects.  These three steps are the heart of lksctp.
	 */
	state_fn = sctp_sm_lookup_event(event_type, state, subtype);

	sctp_init_cmd_seq(&commands);

	DEBUG_PRE;
	status = (*state_fn->fn)(ep, asoc, subtype, event_arg, &commands);
	DEBUG_POST;

	error = sctp_side_effects(event_type, subtype, state,
				  ep, asoc, event_arg, status,
				  &commands, gfp);
	DEBUG_POST_SFX;

	return error;
}

#undef DEBUG_PRE
#undef DEBUG_POST

/*****************************************************************
 * This the master state function side effect processing function.
 *****************************************************************/
static int sctp_side_effects(sctp_event_t event_type, sctp_subtype_t subtype,
			     sctp_state_t state,
			     struct sctp_endpoint *ep,
			     struct sctp_association *asoc,
			     void *event_arg,
			     sctp_disposition_t status,
			     sctp_cmd_seq_t *commands,
			     gfp_t gfp)
{
	int error;

	/* FIXME - Most of the dispositions left today would be categorized
	 * as "exceptional" dispositions.  For those dispositions, it
	 * may not be proper to run through any of the commands at all.
	 * For example, the command interpreter might be run only with
	 * disposition SCTP_DISPOSITION_CONSUME.
	 */
	if (0 != (error = sctp_cmd_interpreter(event_type, subtype, state,
					       ep, asoc,
					       event_arg, status,
					       commands, gfp)))
		goto bail;

	switch (status) {
	case SCTP_DISPOSITION_DISCARD:
		SCTP_DEBUG_PRINTK("Ignored sctp protocol event - state %d, "
				  "event_type %d, event_id %d\n",
				  state, event_type, subtype.chunk);
		break;

	case SCTP_DISPOSITION_NOMEM:
		/* We ran out of memory, so we need to discard this
		 * packet.
		 */
		/* BUG--we should now recover some memory, probably by
		 * reneging...
		 */
		error = -ENOMEM;
		break;

	case SCTP_DISPOSITION_DELETE_TCB:
		/* This should now be a command. */
		break;

	case SCTP_DISPOSITION_CONSUME:
	case SCTP_DISPOSITION_ABORT:
		/*
		 * We should no longer have much work to do here as the
		 * real work has been done as explicit commands above.
		 */
		break;

	case SCTP_DISPOSITION_VIOLATION:
		if (net_ratelimit())
			printk(KERN_ERR "sctp protocol violation state %d "
			       "chunkid %d\n", state, subtype.chunk);
		break;

	case SCTP_DISPOSITION_NOT_IMPL:
		printk(KERN_WARNING "sctp unimplemented feature in state %d, "
		       "event_type %d, event_id %d\n",
		       state, event_type, subtype.chunk);
		break;

	case SCTP_DISPOSITION_BUG:
		printk(KERN_ERR "sctp bug in state %d, "
		       "event_type %d, event_id %d\n",
		       state, event_type, subtype.chunk);
		BUG();
		break;

	default:
		printk(KERN_ERR "sctp impossible disposition %d "
		       "in state %d, event_type %d, event_id %d\n",
		       status, state, event_type, subtype.chunk);
		BUG();
		break;
	}

bail:
	return error;
}

/********************************************************************
 * 2nd Level Abstractions
 ********************************************************************/

/* This is the side-effect interpreter.  */
static int sctp_cmd_interpreter(sctp_event_t event_type,
				sctp_subtype_t subtype,
				sctp_state_t state,
				struct sctp_endpoint *ep,
				struct sctp_association *asoc,
				void *event_arg,
				sctp_disposition_t status,
				sctp_cmd_seq_t *commands,
				gfp_t gfp)
{
	int error = 0;
	int force;
	sctp_cmd_t *cmd;
	struct sctp_chunk *new_obj;
	struct sctp_chunk *chunk = NULL;
	struct sctp_packet *packet;
	struct timer_list *timer;
	unsigned long timeout;
	struct sctp_transport *t;
	struct sctp_sackhdr sackh;
	int local_cork = 0;

	if (SCTP_EVENT_T_TIMEOUT != event_type)
		chunk = (struct sctp_chunk *) event_arg;

	/* Note:  This whole file is a huge candidate for rework.
	 * For example, each command could either have its own handler, so
	 * the loop would look like:
	 *     while (cmds)
	 *         cmd->handle(x, y, z)
	 * --jgrimm
	 */
	while (NULL != (cmd = sctp_next_cmd(commands))) {
		switch (cmd->verb) {
		case SCTP_CMD_NOP:
			/* Do nothing. */
			break;

		case SCTP_CMD_NEW_ASOC:
			/* Register a new association.  */
			if (local_cork) {
				sctp_outq_uncork(&asoc->outqueue);
				local_cork = 0;
			}
			asoc = cmd->obj.ptr;
			/* Register with the endpoint.  */
			sctp_endpoint_add_asoc(ep, asoc);
			sctp_hash_established(asoc);
			break;

		case SCTP_CMD_UPDATE_ASSOC:
		       sctp_assoc_update(asoc, cmd->obj.ptr);
		       break;

		case SCTP_CMD_PURGE_OUTQUEUE:
		       sctp_outq_teardown(&asoc->outqueue);
		       break;

		case SCTP_CMD_DELETE_TCB:
			if (local_cork) {
				sctp_outq_uncork(&asoc->outqueue);
				local_cork = 0;
			}
			/* Delete the current association.  */
			sctp_cmd_delete_tcb(commands, asoc);
			asoc = NULL;
			break;

		case SCTP_CMD_NEW_STATE:
			/* Enter a new state.  */
			sctp_cmd_new_state(commands, asoc, cmd->obj.state);
			break;

		case SCTP_CMD_REPORT_TSN:
			/* Record the arrival of a TSN.  */
			error = sctp_tsnmap_mark(&asoc->peer.tsn_map,
						 cmd->obj.u32);
			break;

		case SCTP_CMD_REPORT_FWDTSN:
			/* Move the Cumulattive TSN Ack ahead. */
			sctp_tsnmap_skip(&asoc->peer.tsn_map, cmd->obj.u32);

			/* purge the fragmentation queue */
			sctp_ulpq_reasm_flushtsn(&asoc->ulpq, cmd->obj.u32);

			/* Abort any in progress partial delivery. */
			sctp_ulpq_abort_pd(&asoc->ulpq, GFP_ATOMIC);
			break;

		case SCTP_CMD_PROCESS_FWDTSN:
			sctp_cmd_process_fwdtsn(&asoc->ulpq, cmd->obj.ptr);
			break;

		case SCTP_CMD_GEN_SACK:
			/* Generate a Selective ACK.
			 * The argument tells us whether to just count
			 * the packet and MAYBE generate a SACK, or
			 * force a SACK out.
			 */
			force = cmd->obj.i32;
			error = sctp_gen_sack(asoc, force, commands);
			break;

		case SCTP_CMD_PROCESS_SACK:
			/* Process an inbound SACK.  */
			error = sctp_cmd_process_sack(commands, asoc,
						      cmd->obj.ptr);
			break;

		case SCTP_CMD_GEN_INIT_ACK:
			/* Generate an INIT ACK chunk.  */
			new_obj = sctp_make_init_ack(asoc, chunk, GFP_ATOMIC,
						     0);
			if (!new_obj)
				goto nomem;

			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
					SCTP_CHUNK(new_obj));
			break;

		case SCTP_CMD_PEER_INIT:
			/* Process a unified INIT from the peer.
			 * Note: Only used during INIT-ACK processing.  If
			 * there is an error just return to the outter
			 * layer which will bail.
			 */
			error = sctp_cmd_process_init(commands, asoc, chunk,
						      cmd->obj.ptr, gfp);
			break;

		case SCTP_CMD_GEN_COOKIE_ECHO:
			/* Generate a COOKIE ECHO chunk.  */
			new_obj = sctp_make_cookie_echo(asoc, chunk);
			if (!new_obj) {
				if (cmd->obj.ptr)
					sctp_chunk_free(cmd->obj.ptr);
				goto nomem;
			}
			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
					SCTP_CHUNK(new_obj));

			/* If there is an ERROR chunk to be sent along with
			 * the COOKIE_ECHO, send it, too.
			 */
			if (cmd->obj.ptr)
				sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
						SCTP_CHUNK(cmd->obj.ptr));

			if (new_obj->transport) {
				new_obj->transport->init_sent_count++;
				asoc->init_last_sent_to = new_obj->transport;
			}

			/* FIXME - Eventually come up with a cleaner way to
			 * enabling COOKIE-ECHO + DATA bundling during
			 * multihoming stale cookie scenarios, the following
			 * command plays with asoc->peer.retran_path to
			 * avoid the problem of sending the COOKIE-ECHO and
			 * DATA in different paths, which could result
			 * in the association being ABORTed if the DATA chunk
			 * is processed first by the server.  Checking the
			 * init error counter simply causes this command
			 * to be executed only during failed attempts of
			 * association establishment.
			 */
			if ((asoc->peer.retran_path !=
			     asoc->peer.primary_path) &&
			    (asoc->init_err_counter > 0)) {
				sctp_add_cmd_sf(commands,
						SCTP_CMD_FORCE_PRIM_RETRAN,
						SCTP_NULL());
			}

			break;

		case SCTP_CMD_GEN_SHUTDOWN:
			/* Generate SHUTDOWN when in SHUTDOWN_SENT state.
			 * Reset error counts.
			 */
			asoc->overall_error_count = 0;

			/* Generate a SHUTDOWN chunk.  */
			new_obj = sctp_make_shutdown(asoc, chunk);
			if (!new_obj)
				goto nomem;
			sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
					SCTP_CHUNK(new_obj));
			break;

		case SCTP_CMD_CHUNK_ULP:
			/* Send a chunk to the sockets layer.  */
			SCTP_DEBUG_PRINTK("sm_sideff: %s %p, %s %p.\n",
					  "chunk_up:", cmd->obj.ptr,
					  "ulpq:", &asoc->ulpq);
			sctp_ulpq_tail_data(&asoc->ulpq, cmd->obj.ptr,
					    GFP_ATOMIC);
			break;

		case SCTP_CMD_EVENT_ULP:
			/* Send a notification to the sockets layer.  */
			SCTP_DEBUG_PRINTK("sm_sideff: %s %p, %s %p.\n",
					  "event_up:",cmd->obj.ptr,
					  "ulpq:",&asoc->ulpq);
			sctp_ulpq_tail_event(&asoc->ulpq, cmd->obj.ptr);
			break;

		case SCTP_CMD_REPLY:
			/* If an caller has not already corked, do cork. */
			if (!asoc->outqueue.cork) {
				sctp_outq_cork(&asoc->outqueue);
				local_cork = 1;
			}
			/* Send a chunk to our peer.  */
			error = sctp_outq_tail(&asoc->outqueue, cmd->obj.ptr);
			break;

		case SCTP_CMD_SEND_PKT:
			/* Send a full packet to our peer.  */
			packet = cmd->obj.ptr;
			sctp_packet_transmit(packet);
			sctp_ootb_pkt_free(packet);
			break;

		case SCTP_CMD_T1_RETRAN:
			/* Mark a transport for retransmission.  */
			sctp_retransmit(&asoc->outqueue, cmd->obj.transport,
					SCTP_RTXR_T1_RTX);
			break;

		case SCTP_CMD_RETRAN:
			/* Mark a transport for retransmission.  */
			sctp_retransmit(&asoc->outqueue, cmd->obj.transport,
					SCTP_RTXR_T3_RTX);
			break;

		case SCTP_CMD_TRANSMIT:
			/* Kick start transmission. */
			error = sctp_outq_uncork(&asoc->outqueue);
			local_cork = 0;
			break;

		case SCTP_CMD_ECN_CE:
			/* Do delayed CE processing.   */
			sctp_do_ecn_ce_work(asoc, cmd->obj.u32);
			break;

		case SCTP_CMD_ECN_ECNE:
			/* Do delayed ECNE processing. */
			new_obj = sctp_do_ecn_ecne_work(asoc, cmd->obj.u32,
							chunk);
			if (new_obj)
				sctp_add_cmd_sf(commands, SCTP_CMD_REPLY,
						SCTP_CHUNK(new_obj));
			break;

		case SCTP_CMD_ECN_CWR:
			/* Do delayed CWR processing.  */
			sctp_do_ecn_cwr_work(asoc, cmd->obj.u32);
			break;

		case SCTP_CMD_SETUP_T2:
			sctp_cmd_setup_t2(commands, asoc, cmd->obj.ptr);
			break;

		case SCTP_CMD_TIMER_START:
			timer = &asoc->timers[cmd->obj.to];
			timeout = asoc->timeouts[cmd->obj.to];
			BUG_ON(!timeout);

			timer->expires = jiffies + timeout;
			sctp_association_hold(asoc);
			add_timer(timer);
			break;

		case SCTP_CMD_TIMER_RESTART:
			timer = &asoc->timers[cmd->obj.to];
			timeout = asoc->timeouts[cmd->obj.to];
			if (!mod_timer(timer, jiffies + timeout))
				sctp_association_hold(asoc);
			break;

		case SCTP_CMD_TIMER_STOP:
			timer = &asoc->timers[cmd->obj.to];
			if (timer_pending(timer) && del_timer(timer))
				sctp_association_put(asoc);
			break;

		case SCTP_CMD_INIT_CHOOSE_TRANSPORT:
			chunk = cmd->obj.ptr;
			t = sctp_assoc_choose_alter_transport(asoc,
						asoc->init_last_sent_to);
			asoc->init_last_sent_to = t;
			chunk->transport = t;
			t->init_sent_count++;
			break;

		case SCTP_CMD_INIT_RESTART:
			/* Do the needed accounting and updates
			 * associated with restarting an initialization
			 * timer. Only multiply the timeout by two if
			 * all transports have been tried at the current
			 * timeout.
			 */
			sctp_cmd_t1_timer_update(asoc,
						SCTP_EVENT_TIMEOUT_T1_INIT,
						"INIT");

			sctp_add_cmd_sf(commands, SCTP_CMD_TIMER_RESTART,
					SCTP_TO(SCTP_EVENT_TIMEOUT_T1_INIT));
			break;

		case SCTP_CMD_COOKIEECHO_RESTART:
			/* Do the needed accounting and updates
			 * associated with restarting an initialization
			 * timer. Only multiply the timeout by two if
			 * all transports have been tried at the current
			 * timeout.
			 */
			sctp_cmd_t1_timer_update(asoc,
						SCTP_EVENT_TIMEOUT_T1_COOKIE,
						"COOKIE");

			/* If we've sent any data bundled with
			 * COOKIE-ECHO we need to resend.
			 */
			list_for_each_entry(t, &asoc->peer.transport_addr_list,
					transports) {
				sctp_retransmit_mark(&asoc->outqueue, t,
					    SCTP_RTXR_T1_RTX);
			}

			sctp_add_cmd_sf(commands,
					SCTP_CMD_TIMER_RESTART,
					SCTP_TO(SCTP_EVENT_TIMEOUT_T1_COOKIE));
			break;

		case SCTP_CMD_INIT_FAILED:
			sctp_cmd_init_failed(commands, asoc, cmd->obj.err);
			break;

		case SCTP_CMD_ASSOC_FAILED:
			sctp_cmd_assoc_failed(commands, asoc, event_type,
					      subtype, chunk, cmd->obj.err);
			break;

		case SCTP_CMD_INIT_COUNTER_INC:
			asoc->init_err_counter++;
			break;

		case SCTP_CMD_INIT_COUNTER_RESET:
			asoc->init_err_counter = 0;
			asoc->init_cycle = 0;
			list_for_each_entry(t, &asoc->peer.transport_addr_list,
					    transports) {
				t->init_sent_count = 0;
			}
			break;

		case SCTP_CMD_REPORT_DUP:
			sctp_tsnmap_mark_dup(&asoc->peer.tsn_map,
					     cmd->obj.u32);
			break;

		case SCTP_CMD_REPORT_BAD_TAG:
			SCTP_DEBUG_PRINTK("vtag mismatch!\n");
			break;

		case SCTP_CMD_STRIKE:
			/* Mark one strike against a transport.  */
			sctp_do_8_2_transport_strike(asoc, cmd->obj.transport,
						    0);
			break;

		case SCTP_CMD_TRANSPORT_IDLE:
			t = cmd->obj.transport;
			sctp_transport_lower_cwnd(t, SCTP_LOWER_CWND_INACTIVE);
			break;

		case SCTP_CMD_TRANSPORT_HB_SENT:
			t = cmd->obj.transport;
			sctp_do_8_2_transport_strike(asoc, t, 1);
			t->hb_sent = 1;
			break;

		case SCTP_CMD_TRANSPORT_ON:
			t = cmd->obj.transport;
			sctp_cmd_transport_on(commands, asoc, t, chunk);
			break;

		case SCTP_CMD_HB_TIMERS_START:
			sctp_cmd_hb_timers_start(commands, asoc);
			break;

		case SCTP_CMD_HB_TIMER_UPDATE:
			t = cmd->obj.transport;
			sctp_cmd_hb_timer_update(commands, t);
			break;

		case SCTP_CMD_HB_TIMERS_STOP:
			sctp_cmd_hb_timers_stop(commands, asoc);
			break;

		case SCTP_CMD_REPORT_ERROR:
			error = cmd->obj.error;
			break;

		case SCTP_CMD_PROCESS_CTSN:
			/* Dummy up a SACK for processing. */
			sackh.cum_tsn_ack = cmd->obj.be32;
			sackh.a_rwnd = 0;
			sackh.num_gap_ack_blocks = 0;
			sackh.num_dup_tsns = 0;
			sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_SACK,
					SCTP_SACKH(&sackh));
			break;

		case SCTP_CMD_DISCARD_PACKET:
			/* We need to discard the whole packet.
			 * Uncork the queue since there might be
			 * responses pending
			 */
			chunk->pdiscard = 1;
			if (asoc) {
				sctp_outq_uncork(&asoc->outqueue);
				local_cork = 0;
			}
			break;

		case SCTP_CMD_RTO_PENDING:
			t = cmd->obj.transport;
			t->rto_pending = 1;
			break;

		case SCTP_CMD_PART_DELIVER:
			sctp_ulpq_partial_delivery(&asoc->ulpq, cmd->obj.ptr,
						   GFP_ATOMIC);
			break;

		case SCTP_CMD_RENEGE:
			sctp_ulpq_renege(&asoc->ulpq, cmd->obj.ptr,
					 GFP_ATOMIC);
			break;

		case SCTP_CMD_SETUP_T4:
			sctp_cmd_setup_t4(commands, asoc, cmd->obj.ptr);
			break;

		case SCTP_CMD_PROCESS_OPERR:
			sctp_cmd_process_operr(commands, asoc, chunk);
			break;
		case SCTP_CMD_CLEAR_INIT_TAG:
			asoc->peer.i.init_tag = 0;
			break;
		case SCTP_CMD_DEL_NON_PRIMARY:
			sctp_cmd_del_non_primary(asoc);
			break;
		case SCTP_CMD_T3_RTX_TIMERS_STOP:
			sctp_cmd_t3_rtx_timers_stop(commands, asoc);
			break;
		case SCTP_CMD_FORCE_PRIM_RETRAN:
			t = asoc->peer.retran_path;
			asoc->peer.retran_path = asoc->peer.primary_path;
			error = sctp_outq_uncork(&asoc->outqueue);
			local_cork = 0;
			asoc->peer.retran_path = t;
			break;
		case SCTP_CMD_SET_SK_ERR:
			sctp_cmd_set_sk_err(asoc, cmd->obj.error);
			break;
		case SCTP_CMD_ASSOC_CHANGE:
			sctp_cmd_assoc_change(commands, asoc,
					      cmd->obj.u8);
			break;
		case SCTP_CMD_ADAPTATION_IND:
			sctp_cmd_adaptation_ind(commands, asoc);
			break;

		case SCTP_CMD_ASSOC_SHKEY:
			error = sctp_auth_asoc_init_active_key(asoc,
						GFP_ATOMIC);
			break;
		case SCTP_CMD_UPDATE_INITTAG:
			asoc->peer.i.init_tag = cmd->obj.u32;
			break;
		case SCTP_CMD_SEND_MSG:
			if (!asoc->outqueue.cork) {
				sctp_outq_cork(&asoc->outqueue);
				local_cork = 1;
			}
			error = sctp_cmd_send_msg(asoc, cmd->obj.msg);
			break;
		default:
			printk(KERN_WARNING "Impossible command: %u, %p\n",
			       cmd->verb, cmd->obj.ptr);
			break;
		}

		if (error)
			break;
	}

out:
	/* If this is in response to a received chunk, wait until
	 * we are done with the packet to open the queue so that we don't
	 * send multiple packets in response to a single request.
	 */
	if (asoc && SCTP_EVENT_T_CHUNK == event_type && chunk) {
		if (chunk->end_of_packet || chunk->singleton)
			sctp_outq_uncork(&asoc->outqueue);
	} else if (local_cork)
			sctp_outq_uncork(&asoc->outqueue);
	return error;
nomem:
	error = -ENOMEM;
	goto out;
}