summaryrefslogtreecommitdiffstats
path: root/net/sctp/associola.c
blob: 03158e3665da0b34786843104d4ab5f4b5fa4736 (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
/* SCTP kernel reference Implementation
 * (C) Copyright IBM Corp. 2001, 2004
 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001 Intel Corp.
 * Copyright (c) 2001 La Monte H.P. Yarroll
 *
 * This file is part of the SCTP kernel reference Implementation
 *
 * This module provides the abstraction for an SCTP association.
 *
 * The SCTP reference 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.
 *
 * The SCTP reference 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@us.ibm.com>
 *    Xingang Guo           <xingang.guo@intel.com>
 *    Hui Huang             <hui.huang@nokia.com>
 *    Sridhar Samudrala	    <sri@us.ibm.com>
 *    Daisy Chang	    <daisyc@us.ibm.com>
 *    Ryan Layer	    <rmlayer@us.ibm.com>
 *    Kevin Gao             <kevin.gao@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/types.h>
#include <linux/fcntl.h>
#include <linux/poll.h>
#include <linux/init.h>

#include <linux/slab.h>
#include <linux/in.h>
#include <net/ipv6.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>

/* Forward declarations for internal functions. */
static void sctp_assoc_bh_rcv(struct work_struct *work);


/* 1st Level Abstractions. */

/* Initialize a new association from provided memory. */
static struct sctp_association *sctp_association_init(struct sctp_association *asoc,
					  const struct sctp_endpoint *ep,
					  const struct sock *sk,
					  sctp_scope_t scope,
					  gfp_t gfp)
{
	struct sctp_sock *sp;
	int i;
	sctp_paramhdr_t *p;
	int err;

	/* Retrieve the SCTP per socket area.  */
	sp = sctp_sk((struct sock *)sk);

	/* Init all variables to a known value.  */
	memset(asoc, 0, sizeof(struct sctp_association));

	/* Discarding const is appropriate here.  */
	asoc->ep = (struct sctp_endpoint *)ep;
	sctp_endpoint_hold(asoc->ep);

	/* Hold the sock.  */
	asoc->base.sk = (struct sock *)sk;
	sock_hold(asoc->base.sk);

	/* Initialize the common base substructure.  */
	asoc->base.type = SCTP_EP_TYPE_ASSOCIATION;

	/* Initialize the object handling fields.  */
	atomic_set(&asoc->base.refcnt, 1);
	asoc->base.dead = 0;
	asoc->base.malloced = 0;

	/* Initialize the bind addr area.  */
	sctp_bind_addr_init(&asoc->base.bind_addr, ep->base.bind_addr.port);

	asoc->state = SCTP_STATE_CLOSED;

	/* Set these values from the socket values, a conversion between
	 * millsecons to seconds/microseconds must also be done.
	 */
	asoc->cookie_life.tv_sec = sp->assocparams.sasoc_cookie_life / 1000;
	asoc->cookie_life.tv_usec = (sp->assocparams.sasoc_cookie_life % 1000)
					* 1000;
	asoc->frag_point = 0;

	/* Set the association max_retrans and RTO values from the
	 * socket values.
	 */
	asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
	asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
	asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
	asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);

	asoc->overall_error_count = 0;

	/* Initialize the association's heartbeat interval based on the
	 * sock configured value.
	 */
	asoc->hbinterval = msecs_to_jiffies(sp->hbinterval);

	/* Initialize path max retrans value. */
	asoc->pathmaxrxt = sp->pathmaxrxt;

	/* Initialize default path MTU. */
	asoc->pathmtu = sp->pathmtu;

	/* Set association default SACK delay */
	asoc->sackdelay = msecs_to_jiffies(sp->sackdelay);

	/* Set the association default flags controlling
	 * Heartbeat, SACK delay, and Path MTU Discovery.
	 */
	asoc->param_flags = sp->param_flags;

	/* Initialize the maximum mumber of new data packets that can be sent
	 * in a burst.
	 */
	asoc->max_burst = sp->max_burst;

	/* initialize association timers */
	asoc->timeouts[SCTP_EVENT_TIMEOUT_NONE] = 0;
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_COOKIE] = asoc->rto_initial;
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T1_INIT] = asoc->rto_initial;
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T2_SHUTDOWN] = asoc->rto_initial;
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T3_RTX] = 0;
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T4_RTO] = 0;

	/* sctpimpguide Section 2.12.2
	 * If the 'T5-shutdown-guard' timer is used, it SHOULD be set to the
	 * recommended value of 5 times 'RTO.Max'.
	 */
	asoc->timeouts[SCTP_EVENT_TIMEOUT_T5_SHUTDOWN_GUARD]
		= 5 * asoc->rto_max;

	asoc->timeouts[SCTP_EVENT_TIMEOUT_HEARTBEAT] = 0;
	asoc->timeouts[SCTP_EVENT_TIMEOUT_SACK] = asoc->sackdelay;
	asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] =
		sp->autoclose * HZ;

	/* Initilizes the timers */
	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
		init_timer(&asoc->timers[i]);
		asoc->timers[i].function = sctp_timer_events[i];
		asoc->timers[i].data = (unsigned long) asoc;
	}

	/* Pull default initialization values from the sock options.
	 * Note: This assumes that the values have already been
	 * validated in the sock.
	 */
	asoc->c.sinit_max_instreams = sp->initmsg.sinit_max_instreams;
	asoc->c.sinit_num_ostreams  = sp->initmsg.sinit_num_ostreams;
	asoc->max_init_attempts	= sp->initmsg.sinit_max_attempts;

	asoc->max_init_timeo =
		 msecs_to_jiffies(sp->initmsg.sinit_max_init_timeo);

	/* Allocate storage for the ssnmap after the inbound and outbound
	 * streams have been negotiated during Init.
	 */
	asoc->ssnmap = NULL;

	/* Set the local window size for receive.
	 * This is also the rcvbuf space per association.
	 * RFC 6 - A SCTP receiver MUST be able to receive a minimum of
	 * 1500 bytes in one SCTP packet.
	 */
	if ((sk->sk_rcvbuf/2) < SCTP_DEFAULT_MINWINDOW)
		asoc->rwnd = SCTP_DEFAULT_MINWINDOW;
	else
		asoc->rwnd = sk->sk_rcvbuf/2;

	asoc->a_rwnd = asoc->rwnd;

	asoc->rwnd_over = 0;

	/* Use my own max window until I learn something better.  */
	asoc->peer.rwnd = SCTP_DEFAULT_MAXWINDOW;

	/* Set the sndbuf size for transmit.  */
	asoc->sndbuf_used = 0;

	/* Initialize the receive memory counter */
	atomic_set(&asoc->rmem_alloc, 0);

	init_waitqueue_head(&asoc->wait);

	asoc->c.my_vtag = sctp_generate_tag(ep);
	asoc->peer.i.init_tag = 0;     /* INIT needs a vtag of 0. */
	asoc->c.peer_vtag = 0;
	asoc->c.my_ttag   = 0;
	asoc->c.peer_ttag = 0;
	asoc->c.my_port = ep->base.bind_addr.port;

	asoc->c.initial_tsn = sctp_generate_tsn(ep);

	asoc->next_tsn = asoc->c.initial_tsn;

	asoc->ctsn_ack_point = asoc->next_tsn - 1;
	asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
	asoc->highest_sacked = asoc->ctsn_ack_point;
	asoc->last_cwr_tsn = asoc->ctsn_ack_point;
	asoc->unack_data = 0;

	/* ADDIP Section 4.1 Asconf Chunk Procedures
	 *
	 * When an endpoint has an ASCONF signaled change to be sent to the
	 * remote endpoint it should do the following:
	 * ...
	 * A2) a serial number should be assigned to the chunk. The serial
	 * number SHOULD be a monotonically increasing number. The serial
	 * numbers SHOULD be initialized at the start of the
	 * association to the same value as the initial TSN.
	 */
	asoc->addip_serial = asoc->c.initial_tsn;

	INIT_LIST_HEAD(&asoc->addip_chunk_list);

	/* Make an empty list of remote transport addresses.  */
	INIT_LIST_HEAD(&asoc->peer.transport_addr_list);
	asoc->peer.transport_count = 0;

	/* RFC 2960 5.1 Normal Establishment of an Association
	 *
	 * After the reception of the first data chunk in an
	 * association the endpoint must immediately respond with a
	 * sack to acknowledge the data chunk.  Subsequent
	 * acknowledgements should be done as described in Section
	 * 6.2.
	 *
	 * [We implement this by telling a new association that it
	 * already received one packet.]
	 */
	asoc->peer.sack_needed = 1;

	/* Assume that the peer recongizes ASCONF until reported otherwise
	 * via an ERROR chunk.
	 */
	asoc->peer.asconf_capable = 1;

	/* Create an input queue.  */
	sctp_inq_init(&asoc->base.inqueue);
	sctp_inq_set_th_handler(&asoc->base.inqueue, sctp_assoc_bh_rcv);

	/* Create an output queue.  */
	sctp_outq_init(asoc, &asoc->outqueue);

	if (!sctp_ulpq_init(&asoc->ulpq, asoc))
		goto fail_init;

	/* Set up the tsn tracking. */
	sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_SIZE, 0);

	asoc->need_ecne = 0;

	asoc->assoc_id = 0;

	/* Assume that peer would support both address types unless we are
	 * told otherwise.
	 */
	asoc->peer.ipv4_address = 1;
	asoc->peer.ipv6_address = 1;
	INIT_LIST_HEAD(&asoc->asocs);

	asoc->autoclose = sp->autoclose;

	asoc->default_stream = sp->default_stream;
	asoc->default_ppid = sp->default_ppid;
	asoc->default_flags = sp->default_flags;
	asoc->default_context = sp->default_context;
	asoc->default_timetolive = sp->default_timetolive;
	asoc->default_rcv_context = sp->default_rcv_context;

	/* AUTH related initializations */
	INIT_LIST_HEAD(&asoc->endpoint_shared_keys);
	err = sctp_auth_asoc_copy_shkeys(ep, asoc, gfp);
	if (err)
		goto fail_init;

	asoc->active_key_id = ep->active_key_id;
	asoc->asoc_shared_key = NULL;

	asoc->default_hmac_id = 0;
	/* Save the hmacs and chunks list into this association */
	if (ep->auth_hmacs_list)
		memcpy(asoc->c.auth_hmacs, ep->auth_hmacs_list,
			ntohs(ep->auth_hmacs_list->param_hdr.length));
	if (ep->auth_chunk_list)
		memcpy(asoc->c.auth_chunks, ep->auth_chunk_list,
			ntohs(ep->auth_chunk_list->param_hdr.length));

	/* Get the AUTH random number for this association */
	p = (sctp_paramhdr_t *)asoc->c.auth_random;
	p->type = SCTP_PARAM_RANDOM;
	p->length = htons(sizeof(sctp_paramhdr_t) + SCTP_AUTH_RANDOM_LENGTH);
	get_random_bytes(p+1, SCTP_AUTH_RANDOM_LENGTH);

	return asoc;

fail_init:
	sctp_endpoint_put(asoc->ep);
	sock_put(asoc->base.sk);
	return NULL;
}

/* Allocate and initialize a new association */
struct sctp_association *sctp_association_new(const struct sctp_endpoint *ep,
					 const struct sock *sk,
					 sctp_scope_t scope,
					 gfp_t gfp)
{
	struct sctp_association *asoc;

	asoc = t_new(struct sctp_association, gfp);
	if (!asoc)
		goto fail;

	if (!sctp_association_init(asoc, ep, sk, scope, gfp))
		goto fail_init;

	asoc->base.malloced = 1;
	SCTP_DBG_OBJCNT_INC(assoc);
	SCTP_DEBUG_PRINTK("Created asoc %p\n", asoc);

	return asoc;

fail_init:
	kfree(asoc);
fail:
	return NULL;
}

/* Free this association if possible.  There may still be users, so
 * the actual deallocation may be delayed.
 */
void sctp_association_free(struct sctp_association *asoc)
{
	struct sock *sk = asoc->base.sk;
	struct sctp_transport *transport;
	struct list_head *pos, *temp;
	int i;

	/* Only real associations count against the endpoint, so
	 * don't bother for if this is a temporary association.
	 */
	if (!asoc->temp) {
		list_del(&asoc->asocs);

		/* Decrement the backlog value for a TCP-style listening
		 * socket.
		 */
		if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
			sk->sk_ack_backlog--;
	}

	/* Mark as dead, so other users can know this structure is
	 * going away.
	 */
	asoc->base.dead = 1;

	/* Dispose of any data lying around in the outqueue. */
	sctp_outq_free(&asoc->outqueue);

	/* Dispose of any pending messages for the upper layer. */
	sctp_ulpq_free(&asoc->ulpq);

	/* Dispose of any pending chunks on the inqueue. */
	sctp_inq_free(&asoc->base.inqueue);

	/* Free ssnmap storage. */
	sctp_ssnmap_free(asoc->ssnmap);

	/* Clean up the bound address list. */
	sctp_bind_addr_free(&asoc->base.bind_addr);

	/* Do we need to go through all of our timers and
	 * delete them?   To be safe we will try to delete all, but we
	 * should be able to go through and make a guess based
	 * on our state.
	 */
	for (i = SCTP_EVENT_TIMEOUT_NONE; i < SCTP_NUM_TIMEOUT_TYPES; ++i) {
		if (timer_pending(&asoc->timers[i]) &&
		    del_timer(&asoc->timers[i]))
			sctp_association_put(asoc);
	}

	/* Free peer's cached cookie. */
	kfree(asoc->peer.cookie);
	kfree(asoc->peer.peer_random);
	kfree(asoc->peer.peer_chunks);
	kfree(asoc->peer.peer_hmacs);

	/* Release the transport structures. */
	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
		transport = list_entry(pos, struct sctp_transport, transports);
		list_del(pos);
		sctp_transport_free(transport);
	}

	asoc->peer.transport_count = 0;

	/* Free any cached ASCONF_ACK chunk. */
	if (asoc->addip_last_asconf_ack)
		sctp_chunk_free(asoc->addip_last_asconf_ack);

	/* Free any cached ASCONF chunk. */
	if (asoc->addip_last_asconf)
		sctp_chunk_free(asoc->addip_last_asconf);

	/* AUTH - Free the endpoint shared keys */
	sctp_auth_destroy_keys(&asoc->endpoint_shared_keys);

	/* AUTH - Free the association shared key */
	sctp_auth_key_put(asoc->asoc_shared_key);

	sctp_association_put(asoc);
}

/* Cleanup and free up an association. */
static void sctp_association_destroy(struct sctp_association *asoc)
{
	SCTP_ASSERT(asoc->base.dead, "Assoc is not dead", return);

	sctp_endpoint_put(asoc->ep);
	sock_put(asoc->base.sk);

	if (asoc->assoc_id != 0) {
		spin_lock_bh(&sctp_assocs_id_lock);
		idr_remove(&sctp_assocs_id, asoc->assoc_id);
		spin_unlock_bh(&sctp_assocs_id_lock);
	}

	BUG_TRAP(!atomic_read(&asoc->rmem_alloc));

	if (asoc->base.malloced) {
		kfree(asoc);
		SCTP_DBG_OBJCNT_DEC(assoc);
	}
}

/* Change the primary destination address for the peer. */
void sctp_assoc_set_primary(struct sctp_association *asoc,
			    struct sctp_transport *transport)
{
	asoc->peer.primary_path = transport;

	/* Set a default msg_name for events. */
	memcpy(&asoc->peer.primary_addr, &transport->ipaddr,
	       sizeof(union sctp_addr));

	/* If the primary path is changing, assume that the
	 * user wants to use this new path.
	 */
	if ((transport->state == SCTP_ACTIVE) ||
	    (transport->state == SCTP_UNKNOWN))
		asoc->peer.active_path = transport;

	/*
	 * SFR-CACC algorithm:
	 * Upon the receipt of a request to change the primary
	 * destination address, on the data structure for the new
	 * primary destination, the sender MUST do the following:
	 *
	 * 1) If CHANGEOVER_ACTIVE is set, then there was a switch
	 * to this destination address earlier. The sender MUST set
	 * CYCLING_CHANGEOVER to indicate that this switch is a
	 * double switch to the same destination address.
	 */
	if (transport->cacc.changeover_active)
		transport->cacc.cycling_changeover = 1;

	/* 2) The sender MUST set CHANGEOVER_ACTIVE to indicate that
	 * a changeover has occurred.
	 */
	transport->cacc.changeover_active = 1;

	/* 3) The sender MUST store the next TSN to be sent in
	 * next_tsn_at_change.
	 */
	transport->cacc.next_tsn_at_change = asoc->next_tsn;
}

/* Remove a transport from an association.  */
void sctp_assoc_rm_peer(struct sctp_association *asoc,
			struct sctp_transport *peer)
{
	struct list_head	*pos;
	struct sctp_transport	*transport;

	SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_rm_peer:association %p addr: ",
				 " port: %d\n",
				 asoc,
				 (&peer->ipaddr),
				 ntohs(peer->ipaddr.v4.sin_port));

	/* If we are to remove the current retran_path, update it
	 * to the next peer before removing this peer from the list.
	 */
	if (asoc->peer.retran_path == peer)
		sctp_assoc_update_retran_path(asoc);

	/* Remove this peer from the list. */
	list_del(&peer->transports);

	/* Get the first transport of asoc. */
	pos = asoc->peer.transport_addr_list.next;
	transport = list_entry(pos, struct sctp_transport, transports);

	/* Update any entries that match the peer to be deleted. */
	if (asoc->peer.primary_path == peer)
		sctp_assoc_set_primary(asoc, transport);
	if (asoc->peer.active_path == peer)
		asoc->peer.active_path = transport;
	if (asoc->peer.last_data_from == peer)
		asoc->peer.last_data_from = transport;

	/* If we remove the transport an INIT was last sent to, set it to
	 * NULL. Combined with the update of the retran path above, this
	 * will cause the next INIT to be sent to the next available
	 * transport, maintaining the cycle.
	 */
	if (asoc->init_last_sent_to == peer)
		asoc->init_last_sent_to = NULL;

	asoc->peer.transport_count--;

	sctp_transport_free(peer);
}

/* Add a transport address to an association.  */
struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
					   const union sctp_addr *addr,
					   const gfp_t gfp,
					   const int peer_state)
{
	struct sctp_transport *peer;
	struct sctp_sock *sp;
	unsigned short port;

	sp = sctp_sk(asoc->base.sk);

	/* AF_INET and AF_INET6 share common port field. */
	port = ntohs(addr->v4.sin_port);

	SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_add_peer:association %p addr: ",
				 " port: %d state:%d\n",
				 asoc,
				 addr,
				 port,
				 peer_state);

	/* Set the port if it has not been set yet.  */
	if (0 == asoc->peer.port)
		asoc->peer.port = port;

	/* Check to see if this is a duplicate. */
	peer = sctp_assoc_lookup_paddr(asoc, addr);
	if (peer) {
		if (peer->state == SCTP_UNKNOWN) {
			if (peer_state == SCTP_ACTIVE)
				peer->state = SCTP_ACTIVE;
			if (peer_state == SCTP_UNCONFIRMED)
				peer->state = SCTP_UNCONFIRMED;
		}
		return peer;
	}

	peer = sctp_transport_new(addr, gfp);
	if (!peer)
		return NULL;

	sctp_transport_set_owner(peer, asoc);

	/* Initialize the peer's heartbeat interval based on the
	 * association configured value.
	 */
	peer->hbinterval = asoc->hbinterval;

	/* Set the path max_retrans.  */
	peer->pathmaxrxt = asoc->pathmaxrxt;

	/* Initialize the peer's SACK delay timeout based on the
	 * association configured value.
	 */
	peer->sackdelay = asoc->sackdelay;

	/* Enable/disable heartbeat, SACK delay, and path MTU discovery
	 * based on association setting.
	 */
	peer->param_flags = asoc->param_flags;

	/* Initialize the pmtu of the transport. */
	if (peer->param_flags & SPP_PMTUD_ENABLE)
		sctp_transport_pmtu(peer);
	else if (asoc->pathmtu)
		peer->pathmtu = asoc->pathmtu;
	else
		peer->pathmtu = SCTP_DEFAULT_MAXSEGMENT;

	/* If this is the first transport addr on this association,
	 * initialize the association PMTU to the peer's PMTU.
	 * If not and the current association PMTU is higher than the new
	 * peer's PMTU, reset the association PMTU to the new peer's PMTU.
	 */
	if (asoc->pathmtu)
		asoc->pathmtu = min_t(int, peer->pathmtu, asoc->pathmtu);
	else
		asoc->pathmtu = peer->pathmtu;

	SCTP_DEBUG_PRINTK("sctp_assoc_add_peer:association %p PMTU set to "
			  "%d\n", asoc, asoc->pathmtu);

	asoc->frag_point = sctp_frag_point(sp, asoc->pathmtu);

	/* The asoc->peer.port might not be meaningful yet, but
	 * initialize the packet structure anyway.
	 */
	sctp_packet_init(&peer->packet, peer, asoc->base.bind_addr.port,
			 asoc->peer.port);

	/* 7.2.1 Slow-Start
	 *
	 * o The initial cwnd before DATA transmission or after a sufficiently
	 *   long idle period MUST be set to
	 *      min(4*MTU, max(2*MTU, 4380 bytes))
	 *
	 * o The initial value of ssthresh MAY be arbitrarily high
	 *   (for example, implementations MAY use the size of the
	 *   receiver advertised window).
	 */
	peer->cwnd = min(4*asoc->pathmtu, max_t(__u32, 2*asoc->pathmtu, 4380));

	/* At this point, we may not have the receiver's advertised window,
	 * so initialize ssthresh to the default value and it will be set
	 * later when we process the INIT.
	 */
	peer->ssthresh = SCTP_DEFAULT_MAXWINDOW;

	peer->partial_bytes_acked = 0;
	peer->flight_size = 0;

	/* Set the transport's RTO.initial value */
	peer->rto = asoc->rto_initial;

	/* Set the peer's active state. */
	peer->state = peer_state;

	/* Attach the remote transport to our asoc.  */
	list_add_tail(&peer->transports, &asoc->peer.transport_addr_list);
	asoc->peer.transport_count++;

	/* If we do not yet have a primary path, set one.  */
	if (!asoc->peer.primary_path) {
		sctp_assoc_set_primary(asoc, peer);
		asoc->peer.retran_path = peer;
	}

	if (asoc->peer.active_path == asoc->peer.retran_path) {
		asoc->peer.retran_path = peer;
	}

	return peer;
}

/* Delete a transport address from an association.  */
void sctp_assoc_del_peer(struct sctp_association *asoc,
			 const union sctp_addr *addr)
{
	struct list_head	*pos;
	struct list_head	*temp;
	struct sctp_transport	*transport;

	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
		transport = list_entry(pos, struct sctp_transport, transports);
		if (sctp_cmp_addr_exact(addr, &transport->ipaddr)) {
			/* Do book keeping for removing the peer and free it. */
			sctp_assoc_rm_peer(asoc, transport);
			break;
		}
	}
}

/* Lookup a transport by address. */
struct sctp_transport *sctp_assoc_lookup_paddr(
					const struct sctp_association *asoc,
					const union sctp_addr *address)
{
	struct sctp_transport *t;
	struct list_head *pos;

	/* Cycle through all transports searching for a peer address. */

	list_for_each(pos, &asoc->peer.transport_addr_list) {
		t = list_entry(pos, struct sctp_transport, transports);
		if (sctp_cmp_addr_exact(address, &t->ipaddr))
			return t;
	}

	return NULL;
}

/* Engage in transport control operations.
 * Mark the transport up or down and send a notification to the user.
 * Select and update the new active and retran paths.
 */
void sctp_assoc_control_transport(struct sctp_association *asoc,
				  struct sctp_transport *transport,
				  sctp_transport_cmd_t command,
				  sctp_sn_error_t error)
{
	struct sctp_transport *t = NULL;
	struct sctp_transport *first;
	struct sctp_transport *second;
	struct sctp_ulpevent *event;
	struct sockaddr_storage addr;
	struct list_head *pos;
	int spc_state = 0;

	/* Record the transition on the transport.  */
	switch (command) {
	case SCTP_TRANSPORT_UP:
		/* If we are moving from UNCONFIRMED state due
		 * to heartbeat success, report the SCTP_ADDR_CONFIRMED
		 * state to the user, otherwise report SCTP_ADDR_AVAILABLE.
		 */
		if (SCTP_UNCONFIRMED == transport->state &&
		    SCTP_HEARTBEAT_SUCCESS == error)
			spc_state = SCTP_ADDR_CONFIRMED;
		else
			spc_state = SCTP_ADDR_AVAILABLE;
		transport->state = SCTP_ACTIVE;
		break;

	case SCTP_TRANSPORT_DOWN:
		/* if the transort was never confirmed, do not transition it
		 * to inactive state.
		 */
		if (transport->state != SCTP_UNCONFIRMED)
			transport->state = SCTP_INACTIVE;

		spc_state = SCTP_ADDR_UNREACHABLE;
		break;

	default:
		return;
	}

	/* Generate and send a SCTP_PEER_ADDR_CHANGE notification to the
	 * user.
	 */
	memset(&addr, 0, sizeof(struct sockaddr_storage));
	memcpy(&addr, &transport->ipaddr, transport->af_specific->sockaddr_len);
	event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
				0, spc_state, error, GFP_ATOMIC);
	if (event)
		sctp_ulpq_tail_event(&asoc->ulpq, event);

	/* Select new active and retran paths. */

	/* Look for the two most recently used active transports.
	 *
	 * This code produces the wrong ordering whenever jiffies
	 * rolls over, but we still get usable transports, so we don't
	 * worry about it.
	 */
	first = NULL; second = NULL;

	list_for_each(pos, &asoc->peer.transport_addr_list) {
		t = list_entry(pos, struct sctp_transport, transports);

		if ((t->state == SCTP_INACTIVE) ||
		    (t->state == SCTP_UNCONFIRMED))
			continue;
		if (!first || t->last_time_heard > first->last_time_heard) {
			second = first;
			first = t;
		}
		if (!second || t->last_time_heard > second->last_time_heard)
			second = t;
	}

	/* RFC 2960 6.4 Multi-Homed SCTP Endpoints
	 *
	 * By default, an endpoint should always transmit to the
	 * primary path, unless the SCTP user explicitly specifies the
	 * destination transport address (and possibly source
	 * transport address) to use.
	 *
	 * [If the primary is active but not most recent, bump the most
	 * recently used transport.]
	 */
	if (((asoc->peer.primary_path->state == SCTP_ACTIVE) ||
	     (asoc->peer.primary_path->state == SCTP_UNKNOWN)) &&
	    first != asoc->peer.primary_path) {
		second = first;
		first = asoc->peer.primary_path;
	}

	/* If we failed to find a usable transport, just camp on the
	 * primary, even if it is inactive.
	 */
	if (!first) {
		first = asoc->peer.primary_path;
		second = asoc->peer.primary_path;
	}

	/* Set the active and retran transports.  */
	asoc->peer.active_path = first;
	asoc->peer.retran_path = second;
}

/* Hold a reference to an association. */
void sctp_association_hold(struct sctp_association *asoc)
{
	atomic_inc(&asoc->base.refcnt);
}

/* Release a reference to an association and cleanup
 * if there are no more references.
 */
void sctp_association_put(struct sctp_association *asoc)
{
	if (atomic_dec_and_test(&asoc->base.refcnt))
		sctp_association_destroy(asoc);
}

/* Allocate the next TSN, Transmission Sequence Number, for the given
 * association.
 */
__u32 sctp_association_get_next_tsn(struct sctp_association *asoc)
{
	/* From Section 1.6 Serial Number Arithmetic:
	 * Transmission Sequence Numbers wrap around when they reach
	 * 2**32 - 1.  That is, the next TSN a DATA chunk MUST use
	 * after transmitting TSN = 2*32 - 1 is TSN = 0.
	 */
	__u32 retval = asoc->next_tsn;
	asoc->next_tsn++;
	asoc->unack_data++;

	return retval;
}

/* Compare two addresses to see if they match.  Wildcard addresses
 * only match themselves.
 */
int sctp_cmp_addr_exact(const union sctp_addr *ss1,
			const union sctp_addr *ss2)
{
	struct sctp_af *af;

	af = sctp_get_af_specific(ss1->sa.sa_family);
	if (unlikely(!af))
		return 0;

	return af->cmp_addr(ss1, ss2);
}

/* Return an ecne chunk to get prepended to a packet.
 * Note:  We are sly and return a shared, prealloced chunk.  FIXME:
 * No we don't, but we could/should.
 */
struct sctp_chunk *sctp_get_ecne_prepend(struct sctp_association *asoc)
{
	struct sctp_chunk *chunk;

	/* Send ECNE if needed.
	 * Not being able to allocate a chunk here is not deadly.
	 */
	if (asoc->need_ecne)
		chunk = sctp_make_ecne(asoc, asoc->last_ecne_tsn);
	else
		chunk = NULL;

	return chunk;
}

/*
 * Find which transport this TSN was sent on.
 */
struct sctp_transport *sctp_assoc_lookup_tsn(struct sctp_association *asoc,
					     __u32 tsn)
{
	struct sctp_transport *active;
	struct sctp_transport *match;
	struct list_head *entry, *pos;
	struct sctp_transport *transport;
	struct sctp_chunk *chunk;
	__be32 key = htonl(tsn);

	match = NULL;

	/*
	 * FIXME: In general, find a more efficient data structure for
	 * searching.
	 */

	/*
	 * The general strategy is to search each transport's transmitted
	 * list.   Return which transport this TSN lives on.
	 *
	 * Let's be hopeful and check the active_path first.
	 * Another optimization would be to know if there is only one
	 * outbound path and not have to look for the TSN at all.
	 *
	 */

	active = asoc->peer.active_path;

	list_for_each(entry, &active->transmitted) {
		chunk = list_entry(entry, struct sctp_chunk, transmitted_list);

		if (key == chunk->subh.data_hdr->tsn) {
			match = active;
			goto out;
		}
	}

	/* If not found, go search all the other transports. */
	list_for_each(pos, &asoc->peer.transport_addr_list) {
		transport = list_entry(pos, struct sctp_transport, transports);

		if (transport == active)
			break;
		list_for_each(entry, &transport->transmitted) {
			chunk = list_entry(entry, struct sctp_chunk,
					   transmitted_list);
			if (key == chunk->subh.data_hdr->tsn) {
				match = transport;
				goto out;
			}
		}
	}
out:
	return match;
}

/* Is this the association we are looking for? */
struct sctp_transport *sctp_assoc_is_match(struct sctp_association *asoc,
					   const union sctp_addr *laddr,
					   const union sctp_addr *paddr)
{
	struct sctp_transport *transport;

	if ((htons(asoc->base.bind_addr.port) == laddr->v4.sin_port) &&
	    (htons(asoc->peer.port) == paddr->v4.sin_port)) {
		transport = sctp_assoc_lookup_paddr(asoc, paddr);
		if (!transport)
			goto out;

		if (sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
					 sctp_sk(asoc->base.sk)))
			goto out;
	}
	transport = NULL;

out:
	return transport;
}

/* Do delayed input processing.  This is scheduled by sctp_rcv(). */
static void sctp_assoc_bh_rcv(struct work_struct *work)
{
	struct sctp_association *asoc =
		container_of(work, struct sctp_association,
			     base.inqueue.immediate);
	struct sctp_endpoint *ep;
	struct sctp_chunk *chunk;
	struct sock *sk;
	struct sctp_inq *inqueue;
	int state;
	sctp_subtype_t subtype;
	int error = 0;

	/* The association should be held so we should be safe. */
	ep = asoc->ep;
	sk = asoc->base.sk;

	inqueue = &asoc->base.inqueue;
	sctp_association_hold(asoc);
	while (NULL != (chunk = sctp_inq_pop(inqueue))) {
		state = asoc->state;
		subtype = SCTP_ST_CHUNK(chunk->chunk_hdr->type);

		/* SCTP-AUTH, Section 6.3:
		 *    The receiver has a list of chunk types which it expects
		 *    to be received only after an AUTH-chunk.  This list has
		 *    been sent to the peer during the association setup.  It
		 *    MUST silently discard these chunks if they are not placed
		 *    after an AUTH chunk in the packet.
		 */
		if (sctp_auth_recv_cid(subtype.chunk, asoc) && !chunk->auth)
			continue;

		/* Remember where the last DATA chunk came from so we
		 * know where to send the SACK.
		 */
		if (sctp_chunk_is_data(chunk))
			asoc->peer.last_data_from = chunk->transport;
		else
			SCTP_INC_STATS(SCTP_MIB_INCTRLCHUNKS);

		if (chunk->transport)
			chunk->transport->last_time_heard = jiffies;

		/* Run through the state machine. */
		error = sctp_do_sm(SCTP_EVENT_T_CHUNK, subtype,
				   state, ep, asoc, chunk, GFP_ATOMIC);

		/* Check to see if the association is freed in response to
		 * the incoming chunk.  If so, get out of the while loop.
		 */
		if (asoc->base.dead)
			break;

		/* If there is an error on chunk, discard this packet. */
		if (error && chunk)
			chunk->pdiscard = 1;
	}
	sctp_association_put(asoc);
}

/* This routine moves an association from its old sk to a new sk.  */
void sctp_assoc_migrate(struct sctp_association *assoc, struct sock *newsk)
{
	struct sctp_sock *newsp = sctp_sk(newsk);
	struct sock *oldsk = assoc->base.sk;

	/* Delete the association from the old endpoint's list of
	 * associations.
	 */
	list_del_init(&assoc->asocs);

	/* Decrement the backlog value for a TCP-style socket. */
	if (sctp_style(oldsk, TCP))
		oldsk->sk_ack_backlog--;

	/* Release references to the old endpoint and the sock.  */
	sctp_endpoint_put(assoc->ep);
	sock_put(assoc->base.sk);

	/* Get a reference to the new endpoint.  */
	assoc->ep = newsp->ep;
	sctp_endpoint_hold(assoc->ep);

	/* Get a reference to the new sock.  */
	assoc->base.sk = newsk;
	sock_hold(assoc->base.sk);

	/* Add the association to the new endpoint's list of associations.  */
	sctp_endpoint_add_asoc(newsp->ep, assoc);
}

/* Update an association (possibly from unexpected COOKIE-ECHO processing).  */
void sctp_assoc_update(struct sctp_association *asoc,
		       struct sctp_association *new)
{
	struct sctp_transport *trans;
	struct list_head *pos, *temp;

	/* Copy in new parameters of peer. */
	asoc->c = new->c;
	asoc->peer.rwnd = new->peer.rwnd;
	asoc->peer.sack_needed = new->peer.sack_needed;
	asoc->peer.i = new->peer.i;
	sctp_tsnmap_init(&asoc->peer.tsn_map, SCTP_TSN_MAP_SIZE,
			 asoc->peer.i.initial_tsn);

	/* Remove any peer addresses not present in the new association. */
	list_for_each_safe(pos, temp, &asoc->peer.transport_addr_list) {
		trans = list_entry(pos, struct sctp_transport, transports);
		if (!sctp_assoc_lookup_paddr(new, &trans->ipaddr))
			sctp_assoc_del_peer(asoc, &trans->ipaddr);

		if (asoc->state >= SCTP_STATE_ESTABLISHED)
			sctp_transport_reset(trans);
	}

	/* If the case is A (association restart), use
	 * initial_tsn as next_tsn. If the case is B, use
	 * current next_tsn in case data sent to peer
	 * has been discarded and needs retransmission.
	 */
	if (asoc->state >= SCTP_STATE_ESTABLISHED) {
		asoc->next_tsn = new->next_tsn;
		asoc->ctsn_ack_point = new->ctsn_ack_point;
		asoc->adv_peer_ack_point = new->adv_peer_ack_point;

		/* Reinitialize SSN for both local streams
		 * and peer's streams.
		 */
		sctp_ssnmap_clear(asoc->ssnmap);

		/* Flush the ULP reassembly and ordered queue.
		 * Any data there will now be stale and will
		 * cause problems.
		 */
		sctp_ulpq_flush(&asoc->ulpq);

		/* reset the overall association error count so
		 * that the restarted association doesn't get torn
		 * down on the next retransmission timer.
		 */
		asoc->overall_error_count = 0;

	} else {
		/* Add any peer addresses from the new association. */
		list_for_each(pos, &new->peer.transport_addr_list) {
			trans = list_entry(pos, struct sctp_transport,
					   transports);
			if (!sctp_assoc_lookup_paddr(asoc, &trans->ipaddr))
				sctp_assoc_add_peer(asoc, &trans->ipaddr,
						    GFP_ATOMIC, trans->state);
		}

		asoc->ctsn_ack_point = asoc->next_tsn - 1;
		asoc->adv_peer_ack_point = asoc->ctsn_ack_point;
		if (!asoc->ssnmap) {
			/* Move the ssnmap. */
			asoc->ssnmap = new->ssnmap;
			new->ssnmap = NULL;
		}

		if (!asoc->assoc_id) {
			/* get a new association id since we don't have one
			 * yet.
			 */
			sctp_assoc_set_id(asoc, GFP_ATOMIC);
		}
	}

	/* SCTP-AUTH: Save the peer parameters from the new assocaitions
	 * and also move the association shared keys over
	 */
	kfree(asoc->peer.peer_random);
	asoc->peer.peer_random = new->peer.peer_random;
	new->peer.peer_random = NULL;

	kfree(asoc->peer.peer_chunks);
	asoc->peer.peer_chunks = new->peer.peer_chunks;
	new->peer.peer_chunks = NULL;

	kfree(asoc->peer.peer_hmacs);
	asoc->peer.peer_hmacs = new->peer.peer_hmacs;
	new->peer.peer_hmacs = NULL;

	sctp_auth_key_put(asoc->asoc_shared_key);
	sctp_auth_asoc_init_active_key(asoc, GFP_ATOMIC);
}

/* Update the retran path for sending a retransmitted packet.
 * Round-robin through the active transports, else round-robin
 * through the inactive transports as this is the next best thing
 * we can try.
 */
void sctp_assoc_update_retran_path(struct sctp_association *asoc)
{
	struct sctp_transport *t, *next;
	struct list_head *head = &asoc->peer.transport_addr_list;
	struct list_head *pos;

	/* Find the next transport in a round-robin fashion. */
	t = asoc->peer.retran_path;
	pos = &t->transports;
	next = NULL;

	while (1) {
		/* Skip the head. */
		if (pos->next == head)
			pos = head->next;
		else
			pos = pos->next;

		t = list_entry(pos, struct sctp_transport, transports);

		/* Try to find an active transport. */

		if ((t->state == SCTP_ACTIVE) ||
		    (t->state == SCTP_UNKNOWN)) {
			break;
		} else {
			/* Keep track of the next transport in case
			 * we don't find any active transport.
			 */
			if (!next)
				next = t;
		}

		/* We have exhausted the list, but didn't find any
		 * other active transports.  If so, use the next
		 * transport.
		 */
		if (t == asoc->peer.retran_path) {
			t = next;
			break;
		}
	}

	asoc->peer.retran_path = t;

	SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_update_retran_path:association"
				 " %p addr: ",
				 " port: %d\n",
				 asoc,
				 (&t->ipaddr),
				 ntohs(t->ipaddr.v4.sin_port));
}

/* Choose the transport for sending a INIT packet.  */
struct sctp_transport *sctp_assoc_choose_init_transport(
	struct sctp_association *asoc)
{
	struct sctp_transport *t;

	/* Use the retran path. If the last INIT was sent over the
	 * retran path, update the retran path and use it.
	 */
	if (!asoc->init_last_sent_to) {
		t = asoc->peer.active_path;
	} else {
		if (asoc->init_last_sent_to == asoc->peer.retran_path)
			sctp_assoc_update_retran_path(asoc);
		t = asoc->peer.retran_path;
	}

	SCTP_DEBUG_PRINTK_IPADDR("sctp_assoc_update_retran_path:association"
				 " %p addr: ",
				 " port: %d\n",
				 asoc,
				 (&t->ipaddr),
				 ntohs(t->ipaddr.v4.sin_port));

	return t;
}

/* Choose the transport for sending a SHUTDOWN packet.  */
struct sctp_transport *sctp_assoc_choose_shutdown_transport(
	struct sctp_association *asoc)
{
	/* If this is the first time SHUTDOWN is sent, use the active path,
	 * else use the retran path. If the last SHUTDOWN was sent over the
	 * retran path, update the retran path and use it.
	 */
	if (!asoc->shutdown_last_sent_to)
		return asoc->peer.active_path;
	else {
		if (asoc->shutdown_last_sent_to == asoc->peer.retran_path)
			sctp_assoc_update_retran_path(asoc);
		return asoc->peer.retran_path;
	}

}

/* Update the association's pmtu and frag_point by going through all the
 * transports. This routine is called when a transport's PMTU has changed.
 */
void sctp_assoc_sync_pmtu(struct sctp_association *asoc)
{
	struct sctp_transport *t;
	struct list_head *pos;
	__u32 pmtu = 0;

	if (!asoc)
		return;

	/* Get the lowest pmtu of all the transports. */
	list_for_each(pos, &asoc->peer.transport_addr_list) {
		t = list_entry(pos, struct sctp_transport, transports);
		if (t->pmtu_pending && t->dst) {
			sctp_transport_update_pmtu(t, dst_mtu(t->dst));
			t->pmtu_pending = 0;
		}
		if (!pmtu || (t->pathmtu < pmtu))
			pmtu = t->pathmtu;
	}

	if (pmtu) {
		struct sctp_sock *sp = sctp_sk(asoc->base.sk);
		asoc->pathmtu = pmtu;
		asoc->frag_point = sctp_frag_point(sp, pmtu);
	}

	SCTP_DEBUG_PRINTK("%s: asoc:%p, pmtu:%d, frag_point:%d\n",
			  __FUNCTION__, asoc, asoc->pathmtu, asoc->frag_point);
}

/* Should we send a SACK to update our peer? */
static inline int sctp_peer_needs_update(struct sctp_association *asoc)
{
	switch (asoc->state) {
	case SCTP_STATE_ESTABLISHED:
	case SCTP_STATE_SHUTDOWN_PENDING:
	case SCTP_STATE_SHUTDOWN_RECEIVED:
	case SCTP_STATE_SHUTDOWN_SENT:
		if ((asoc->rwnd > asoc->a_rwnd) &&
		    ((asoc->rwnd - asoc->a_rwnd) >=
		     min_t(__u32, (asoc->base.sk->sk_rcvbuf >> 1), asoc->pathmtu)))
			return 1;
		break;
	default:
		break;
	}
	return 0;
}

/* Increase asoc's rwnd by len and send any window update SACK if needed. */
void sctp_assoc_rwnd_increase(struct sctp_association *asoc, unsigned len)
{
	struct sctp_chunk *sack;
	struct timer_list *timer;

	if (asoc->rwnd_over) {
		if (asoc->rwnd_over >= len) {
			asoc->rwnd_over -= len;
		} else {
			asoc->rwnd += (len - asoc->rwnd_over);
			asoc->rwnd_over = 0;
		}
	} else {
		asoc->rwnd += len;
	}

	SCTP_DEBUG_PRINTK("%s: asoc %p rwnd increased by %d to (%u, %u) "
			  "- %u\n", __FUNCTION__, asoc, len, asoc->rwnd,
			  asoc->rwnd_over, asoc->a_rwnd);

	/* Send a window update SACK if the rwnd has increased by at least the
	 * minimum of the association's PMTU and half of the receive buffer.
	 * The algorithm used is similar to the one described in
	 * Section 4.2.3.3 of RFC 1122.
	 */
	if (sctp_peer_needs_update(asoc)) {
		asoc->a_rwnd = asoc->rwnd;
		SCTP_DEBUG_PRINTK("%s: Sending window update SACK- asoc: %p "
				  "rwnd: %u a_rwnd: %u\n", __FUNCTION__,
				  asoc, asoc->rwnd, asoc->a_rwnd);
		sack = sctp_make_sack(asoc);
		if (!sack)
			return;

		asoc->peer.sack_needed = 0;

		sctp_outq_tail(&asoc->outqueue, sack);

		/* Stop the SACK timer.  */
		timer = &asoc->timers[SCTP_EVENT_TIMEOUT_SACK];
		if (timer_pending(timer) && del_timer(timer))
			sctp_association_put(asoc);
	}
}

/* Decrease asoc's rwnd by len. */
void sctp_assoc_rwnd_decrease(struct sctp_association *asoc, unsigned len)
{
	SCTP_ASSERT(asoc->rwnd, "rwnd zero", return);
	SCTP_ASSERT(!asoc->rwnd_over, "rwnd_over not zero", return);
	if (asoc->rwnd >= len) {
		asoc->rwnd -= len;
	} else {
		asoc->rwnd_over = len - asoc->rwnd;
		asoc->rwnd = 0;
	}
	SCTP_DEBUG_PRINTK("%s: asoc %p rwnd decreased by %d to (%u, %u)\n",
			  __FUNCTION__, asoc, len, asoc->rwnd,
			  asoc->rwnd_over);
}

/* Build the bind address list for the association based on info from the
 * local endpoint and the remote peer.
 */
int sctp_assoc_set_bind_addr_from_ep(struct sctp_association *asoc,
				     gfp_t gfp)
{
	sctp_scope_t scope;
	int flags;

	/* Use scoping rules to determine the subset of addresses from
	 * the endpoint.
	 */
	scope = sctp_scope(&asoc->peer.active_path->ipaddr);
	flags = (PF_INET6 == asoc->base.sk->sk_family) ? SCTP_ADDR6_ALLOWED : 0;
	if (asoc->peer.ipv4_address)
		flags |= SCTP_ADDR4_PEERSUPP;
	if (asoc->peer.ipv6_address)
		flags |= SCTP_ADDR6_PEERSUPP;

	return sctp_bind_addr_copy(&asoc->base.bind_addr,
				   &asoc->ep->base.bind_addr,
				   scope, gfp, flags);
}

/* Build the association's bind address list from the cookie.  */
int sctp_assoc_set_bind_addr_from_cookie(struct sctp_association *asoc,
					 struct sctp_cookie *cookie,
					 gfp_t gfp)
{
	int var_size2 = ntohs(cookie->peer_init->chunk_hdr.length);
	int var_size3 = cookie->raw_addr_list_len;
	__u8 *raw = (__u8 *)cookie->peer_init + var_size2;

	return sctp_raw_to_bind_addrs(&asoc->base.bind_addr, raw, var_size3,
				      asoc->ep->base.bind_addr.port, gfp);
}

/* Lookup laddr in the bind address list of an association. */
int sctp_assoc_lookup_laddr(struct sctp_association *asoc,
			    const union sctp_addr *laddr)
{
	int found = 0;

	if ((asoc->base.bind_addr.port == ntohs(laddr->v4.sin_port)) &&
	    sctp_bind_addr_match(&asoc->base.bind_addr, laddr,
				 sctp_sk(asoc->base.sk)))
		found = 1;

	return found;
}

/* Set an association id for a given association */
int sctp_assoc_set_id(struct sctp_association *asoc, gfp_t gfp)
{
	int assoc_id;
	int error = 0;
retry:
	if (unlikely(!idr_pre_get(&sctp_assocs_id, gfp)))
		return -ENOMEM;

	spin_lock_bh(&sctp_assocs_id_lock);
	error = idr_get_new_above(&sctp_assocs_id, (void *)asoc,
				    1, &assoc_id);
	spin_unlock_bh(&sctp_assocs_id_lock);
	if (error == -EAGAIN)
		goto retry;
	else if (error)
		return error;

	asoc->assoc_id = (sctp_assoc_t) assoc_id;
	return error;
}
OpenPOWER on IntegriCloud