summaryrefslogtreecommitdiff
path: root/sys/kern/uipc_socket2.c
blob: 3c440a7851882747dce209faf1d9c7eea75a618b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
/*	$NetBSD: uipc_socket2.c,v 1.142 2022/10/26 23:38:09 riastradh Exp $	*/

/*-
 * Copyright (c) 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Copyright (c) 1982, 1986, 1988, 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)uipc_socket2.c	8.2 (Berkeley) 2/14/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uipc_socket2.c,v 1.142 2022/10/26 23:38:09 riastradh Exp $");

#ifdef _KERNEL_OPT
#include "opt_ddb.h"
#include "opt_inet.h"
#include "opt_mbuftrace.h"
#include "opt_sb_max.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/file.h>
#include <sys/buf.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/domain.h>
#include <sys/poll.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/signalvar.h>
#include <sys/kauth.h>
#include <sys/pool.h>
#include <sys/uidinfo.h>

#ifdef DDB
#include <sys/filedesc.h>
#include <ddb/db_active.h>
#endif

/*
 * Primitive routines for operating on sockets and socket buffers.
 *
 * Connection life-cycle:
 *
 *	Normal sequence from the active (originating) side:
 *
 *	- soisconnecting() is called during processing of connect() call,
 *	- resulting in an eventual call to soisconnected() if/when the
 *	  connection is established.
 *
 *	When the connection is torn down during processing of disconnect():
 *
 *	- soisdisconnecting() is called and,
 *	- soisdisconnected() is called when the connection to the peer
 *	  is totally severed.
 *
 *	The semantics of these routines are such that connectionless protocols
 *	can call soisconnected() and soisdisconnected() only, bypassing the
 *	in-progress calls when setting up a ``connection'' takes no time.
 *
 *	From the passive side, a socket is created with two queues of sockets:
 *
 *	- so_q0 (0) for partial connections (i.e. connections in progress)
 *	- so_q (1) for connections already made and awaiting user acceptance.
 *
 *	As a protocol is preparing incoming connections, it creates a socket
 *	structure queued on so_q0 by calling sonewconn().  When the connection
 *	is established, soisconnected() is called, and transfers the
 *	socket structure to so_q, making it available to accept().
 *
 *	If a socket is closed with sockets on either so_q0 or so_q, these
 *	sockets are dropped.
 *
 * Locking rules and assumptions:
 *
 * o socket::so_lock can change on the fly.  The low level routines used
 *   to lock sockets are aware of this.  When so_lock is acquired, the
 *   routine locking must check to see if so_lock still points to the
 *   lock that was acquired.  If so_lock has changed in the meantime, the
 *   now irrelevant lock that was acquired must be dropped and the lock
 *   operation retried.  Although not proven here, this is completely safe
 *   on a multiprocessor system, even with relaxed memory ordering, given
 *   the next two rules:
 *
 * o In order to mutate so_lock, the lock pointed to by the current value
 *   of so_lock must be held: i.e., the socket must be held locked by the
 *   changing thread.  The thread must issue membar_release() to prevent
 *   memory accesses being reordered, and can set so_lock to the desired
 *   value.  If the lock pointed to by the new value of so_lock is not
 *   held by the changing thread, the socket must then be considered
 *   unlocked.
 *
 * o If so_lock is mutated, and the previous lock referred to by so_lock
 *   could still be visible to other threads in the system (e.g. via file
 *   descriptor or protocol-internal reference), then the old lock must
 *   remain valid until the socket and/or protocol control block has been
 *   torn down.
 *
 * o If a socket has a non-NULL so_head value (i.e. is in the process of
 *   connecting), then locking the socket must also lock the socket pointed
 *   to by so_head: their lock pointers must match.
 *
 * o If a socket has connections in progress (so_q, so_q0 not empty) then
 *   locking the socket must also lock the sockets attached to both queues.
 *   Again, their lock pointers must match.
 *
 * o Beyond the initial lock assignment in socreate(), assigning locks to
 *   sockets is the responsibility of the individual protocols / protocol
 *   domains.
 */

static pool_cache_t	socket_cache;
u_long			sb_max = SB_MAX;/* maximum socket buffer size */
static u_long		sb_max_adj;	/* adjusted sb_max */

void
soisconnecting(struct socket *so)
{

	KASSERT(solocked(so));

	so->so_state &= ~(SS_ISCONNECTED|SS_ISDISCONNECTING);
	so->so_state |= SS_ISCONNECTING;
}

void
soisconnected(struct socket *so)
{
	struct socket	*head;

	head = so->so_head;

	KASSERT(solocked(so));
	KASSERT(head == NULL || solocked2(so, head));

	so->so_state &= ~(SS_ISCONNECTING | SS_ISDISCONNECTING);
	so->so_state |= SS_ISCONNECTED;
	if (head && so->so_onq == &head->so_q0) {
		if ((so->so_options & SO_ACCEPTFILTER) == 0) {
			/*
			 * Re-enqueue and wake up any waiters, e.g.
			 * processes blocking on accept().
			 */
			soqremque(so, 0);
			soqinsque(head, so, 1);
			sorwakeup(head);
			cv_broadcast(&head->so_cv);
		} else {
			so->so_upcall =
			    head->so_accf->so_accept_filter->accf_callback;
			so->so_upcallarg = head->so_accf->so_accept_filter_arg;
			so->so_rcv.sb_flags |= SB_UPCALL;
			so->so_options &= ~SO_ACCEPTFILTER;
			(*so->so_upcall)(so, so->so_upcallarg,
					 POLLIN|POLLRDNORM, M_DONTWAIT);
		}
	} else {
		cv_broadcast(&so->so_cv);
		sorwakeup(so);
		sowwakeup(so);
	}
}

void
soisdisconnecting(struct socket *so)
{

	KASSERT(solocked(so));

	so->so_state &= ~SS_ISCONNECTING;
	so->so_state |= (SS_ISDISCONNECTING|SS_CANTRCVMORE|SS_CANTSENDMORE);
	cv_broadcast(&so->so_cv);
	sowwakeup(so);
	sorwakeup(so);
}

void
soisdisconnected(struct socket *so)
{

	KASSERT(solocked(so));

	so->so_state &= ~(SS_ISCONNECTING|SS_ISCONNECTED|SS_ISDISCONNECTING);
	so->so_state |= (SS_CANTRCVMORE|SS_CANTSENDMORE|SS_ISDISCONNECTED);
	cv_broadcast(&so->so_cv);
	sowwakeup(so);
	sorwakeup(so);
}

void
soinit2(void)
{

	socket_cache = pool_cache_init(sizeof(struct socket), 0, 0, 0,
	    "socket", NULL, IPL_SOFTNET, NULL, NULL, NULL);
}

/*
 * sonewconn: accept a new connection.
 *
 * When an attempt at a new connection is noted on a socket which accepts
 * connections, sonewconn(9) is called.  If the connection is possible
 * (subject to space constraints, etc) then we allocate a new structure,
 * properly linked into the data structure of the original socket.
 *
 * => If 'soready' is true, then socket will become ready for accept() i.e.
 *    inserted into the so_q queue, SS_ISCONNECTED set and waiters awoken.
 * => May be called from soft-interrupt context.
 * => Listening socket should be locked.
 * => Returns the new socket locked.
 */
struct socket *
sonewconn(struct socket *head, bool soready)
{
	struct socket *so;
	int soqueue, error;

	KASSERT(solocked(head));

	if (head->so_qlen + head->so_q0len > 3 * head->so_qlimit / 2) {
		/*
		 * Listen queue overflow.  If there is an accept filter
		 * active, pass through the oldest cxn it's handling.
		 */
		if (head->so_accf == NULL) {
			return NULL;
		} else {
			struct socket *so2, *next;

			/* Pass the oldest connection waiting in the
			   accept filter */
			for (so2 = TAILQ_FIRST(&head->so_q0);
			     so2 != NULL; so2 = next) {
				next = TAILQ_NEXT(so2, so_qe);
				if (so2->so_upcall == NULL) {
					continue;
				}
				so2->so_upcall = NULL;
				so2->so_upcallarg = NULL;
				so2->so_options &= ~SO_ACCEPTFILTER;
				so2->so_rcv.sb_flags &= ~SB_UPCALL;
				soisconnected(so2);
				break;
			}

			/* If nothing was nudged out of the acept filter, bail
			 * out; otherwise proceed allocating the socket. */
			if (so2 == NULL) {
				return NULL;
			}
		}
	}
	if ((head->so_options & SO_ACCEPTFILTER) != 0) {
		soready = false;
	}
	soqueue = soready ? 1 : 0;

	if ((so = soget(false)) == NULL) {
		return NULL;
	}
	so->so_type = head->so_type;
	so->so_options = head->so_options & ~SO_ACCEPTCONN;
	so->so_linger = head->so_linger;
	so->so_state = head->so_state | SS_NOFDREF;
	so->so_proto = head->so_proto;
	so->so_timeo = head->so_timeo;
	so->so_pgid = head->so_pgid;
	so->so_send = head->so_send;
	so->so_receive = head->so_receive;
	so->so_uidinfo = head->so_uidinfo;
	so->so_egid = head->so_egid;
	so->so_cpid = head->so_cpid;

	/*
	 * Share the lock with the listening-socket, it may get unshared
	 * once the connection is complete.
	 *
	 * so_lock is stable while we hold the socket locked, so no
	 * need for atomic_load_* here.
	 */
	mutex_obj_hold(head->so_lock);
	so->so_lock = head->so_lock;

	/*
	 * Reserve the space for socket buffers.
	 */
#ifdef MBUFTRACE
	so->so_mowner = head->so_mowner;
	so->so_rcv.sb_mowner = head->so_rcv.sb_mowner;
	so->so_snd.sb_mowner = head->so_snd.sb_mowner;
#endif
	if (soreserve(so, head->so_snd.sb_hiwat, head->so_rcv.sb_hiwat)) {
		goto out;
	}
	so->so_snd.sb_lowat = head->so_snd.sb_lowat;
	so->so_rcv.sb_lowat = head->so_rcv.sb_lowat;
	so->so_rcv.sb_timeo = head->so_rcv.sb_timeo;
	so->so_snd.sb_timeo = head->so_snd.sb_timeo;
	so->so_rcv.sb_flags |= head->so_rcv.sb_flags & (SB_AUTOSIZE | SB_ASYNC);
	so->so_snd.sb_flags |= head->so_snd.sb_flags & (SB_AUTOSIZE | SB_ASYNC);

	/*
	 * Finally, perform the protocol attach.  Note: a new socket
	 * lock may be assigned at this point (if so, it will be held).
	 */
	error = (*so->so_proto->pr_usrreqs->pr_attach)(so, 0);
	if (error) {
out:
		KASSERT(solocked(so));
		KASSERT(so->so_accf == NULL);
		soput(so);

		/* Note: the listening socket shall stay locked. */
		KASSERT(solocked(head));
		return NULL;
	}
	KASSERT(solocked2(head, so));

	/*
	 * Insert into the queue.  If ready, update the connection status
	 * and wake up any waiters, e.g. processes blocking on accept().
	 */
	soqinsque(head, so, soqueue);
	if (soready) {
		so->so_state |= SS_ISCONNECTED;
		sorwakeup(head);
		cv_broadcast(&head->so_cv);
	}
	return so;
}

struct socket *
soget(bool waitok)
{
	struct socket *so;

	so = pool_cache_get(socket_cache, (waitok ? PR_WAITOK : PR_NOWAIT));
	if (__predict_false(so == NULL))
		return (NULL);
	memset(so, 0, sizeof(*so));
	TAILQ_INIT(&so->so_q0);
	TAILQ_INIT(&so->so_q);
	cv_init(&so->so_cv, "socket");
	cv_init(&so->so_rcv.sb_cv, "netio");
	cv_init(&so->so_snd.sb_cv, "netio");
	selinit(&so->so_rcv.sb_sel);
	selinit(&so->so_snd.sb_sel);
	so->so_rcv.sb_so = so;
	so->so_snd.sb_so = so;
	return so;
}

void
soput(struct socket *so)
{

	KASSERT(!cv_has_waiters(&so->so_cv));
	KASSERT(!cv_has_waiters(&so->so_rcv.sb_cv));
	KASSERT(!cv_has_waiters(&so->so_snd.sb_cv));
	seldestroy(&so->so_rcv.sb_sel);
	seldestroy(&so->so_snd.sb_sel);
	mutex_obj_free(so->so_lock);
	cv_destroy(&so->so_cv);
	cv_destroy(&so->so_rcv.sb_cv);
	cv_destroy(&so->so_snd.sb_cv);
	pool_cache_put(socket_cache, so);
}

/*
 * soqinsque: insert socket of a new connection into the specified
 * accept queue of the listening socket (head).
 *
 *	q = 0: queue of partial connections
 *	q = 1: queue of incoming connections
 */
void
soqinsque(struct socket *head, struct socket *so, int q)
{
	KASSERT(q == 0 || q == 1);
	KASSERT(solocked2(head, so));
	KASSERT(so->so_onq == NULL);
	KASSERT(so->so_head == NULL);

	so->so_head = head;
	if (q == 0) {
		head->so_q0len++;
		so->so_onq = &head->so_q0;
	} else {
		head->so_qlen++;
		so->so_onq = &head->so_q;
	}
	TAILQ_INSERT_TAIL(so->so_onq, so, so_qe);
}

/*
 * soqremque: remove socket from the specified queue.
 *
 * => Returns true if socket was removed from the specified queue.
 * => False if socket was not removed (because it was in other queue).
 */
bool
soqremque(struct socket *so, int q)
{
	struct socket *head = so->so_head;

	KASSERT(q == 0 || q == 1);
	KASSERT(solocked(so));
	KASSERT(so->so_onq != NULL);
	KASSERT(head != NULL);

	if (q == 0) {
		if (so->so_onq != &head->so_q0)
			return false;
		head->so_q0len--;
	} else {
		if (so->so_onq != &head->so_q)
			return false;
		head->so_qlen--;
	}
	KASSERT(solocked2(so, head));
	TAILQ_REMOVE(so->so_onq, so, so_qe);
	so->so_onq = NULL;
	so->so_head = NULL;
	return true;
}

/*
 * socantsendmore: indicates that no more data will be sent on the
 * socket; it would normally be applied to a socket when the user
 * informs the system that no more data is to be sent, by the protocol
 * code (in case pr_shutdown()).
 */
void
socantsendmore(struct socket *so)
{
	KASSERT(solocked(so));

	so->so_state |= SS_CANTSENDMORE;
	sowwakeup(so);
}

/*
 * socantrcvmore(): indicates that no more data will be received and
 * will normally be applied to the socket by a protocol when it detects
 * that the peer will send no more data.  Data queued for reading in
 * the socket may yet be read.
 */
void
socantrcvmore(struct socket *so)
{
	KASSERT(solocked(so));

	so->so_state |= SS_CANTRCVMORE;
	sorwakeup(so);
}

/*
 * soroverflow(): indicates that data was attempted to be sent
 * but the receiving buffer overflowed.
 */
void
soroverflow(struct socket *so)
{
	KASSERT(solocked(so));

	so->so_rcv.sb_overflowed++;
	if (so->so_options & SO_RERROR)  {
		so->so_rerror = ENOBUFS;
		sorwakeup(so);
	}
}

/*
 * Wait for data to arrive at/drain from a socket buffer.
 */
int
sbwait(struct sockbuf *sb)
{
	struct socket *so;
	kmutex_t *lock;
	int error;

	so = sb->sb_so;

	KASSERT(solocked(so));

	sb->sb_flags |= SB_NOTIFY;
	lock = so->so_lock;
	if ((sb->sb_flags & SB_NOINTR) != 0)
		error = cv_timedwait(&sb->sb_cv, lock, sb->sb_timeo);
	else
		error = cv_timedwait_sig(&sb->sb_cv, lock, sb->sb_timeo);
	if (__predict_false(lock != atomic_load_relaxed(&so->so_lock)))
		solockretry(so, lock);
	return error;
}

/*
 * Wakeup processes waiting on a socket buffer.
 * Do asynchronous notification via SIGIO
 * if the socket buffer has the SB_ASYNC flag set.
 */
void
sowakeup(struct socket *so, struct sockbuf *sb, int code)
{
	int band;

	KASSERT(solocked(so));
	KASSERT(sb->sb_so == so);

	switch (code) {
	case POLL_IN:
		band = POLLIN|POLLRDNORM;
		break;

	case POLL_OUT:
		band = POLLOUT|POLLWRNORM;
		break;

	case POLL_HUP:
		band = POLLHUP;
		break;

	default:
		band = 0;
#ifdef DIAGNOSTIC
		printf("bad siginfo code %d in socket notification.\n", code);
#endif 
		break;
	}

	sb->sb_flags &= ~SB_NOTIFY;
	selnotify(&sb->sb_sel, band, NOTE_SUBMIT);
	cv_broadcast(&sb->sb_cv);
	if (sb->sb_flags & SB_ASYNC)
		fownsignal(so->so_pgid, SIGIO, code, band, so);
	if (sb->sb_flags & SB_UPCALL)
		(*so->so_upcall)(so, so->so_upcallarg, band, M_DONTWAIT);
}

/*
 * Reset a socket's lock pointer.  Wake all threads waiting on the
 * socket's condition variables so that they can restart their waits
 * using the new lock.  The existing lock must be held.
 *
 * Caller must have issued membar_release before this.
 */
void
solockreset(struct socket *so, kmutex_t *lock)
{

	KASSERT(solocked(so));

	so->so_lock = lock;
	cv_broadcast(&so->so_snd.sb_cv);
	cv_broadcast(&so->so_rcv.sb_cv);
	cv_broadcast(&so->so_cv);
}

/*
 * Socket buffer (struct sockbuf) utility routines.
 *
 * Each socket contains two socket buffers: one for sending data and
 * one for receiving data.  Each buffer contains a queue of mbufs,
 * information about the number of mbufs and amount of data in the
 * queue, and other fields allowing poll() statements and notification
 * on data availability to be implemented.
 *
 * Data stored in a socket buffer is maintained as a list of records.
 * Each record is a list of mbufs chained together with the m_next
 * field.  Records are chained together with the m_nextpkt field. The upper
 * level routine soreceive() expects the following conventions to be
 * observed when placing information in the receive buffer:
 *
 * 1. If the protocol requires each message be preceded by the sender's
 *    name, then a record containing that name must be present before
 *    any associated data (mbuf's must be of type MT_SONAME).
 * 2. If the protocol supports the exchange of ``access rights'' (really
 *    just additional data associated with the message), and there are
 *    ``rights'' to be received, then a record containing this data
 *    should be present (mbuf's must be of type MT_CONTROL).
 * 3. If a name or rights record exists, then it must be followed by
 *    a data record, perhaps of zero length.
 *
 * Before using a new socket structure it is first necessary to reserve
 * buffer space to the socket, by calling sbreserve().  This should commit
 * some of the available buffer space in the system buffer pool for the
 * socket (currently, it does nothing but enforce limits).  The space
 * should be released by calling sbrelease() when the socket is destroyed.
 */

int
sb_max_set(u_long new_sbmax)
{
	int s;

	if (new_sbmax < (16 * 1024))
		return (EINVAL);

	s = splsoftnet();
	sb_max = new_sbmax;
	sb_max_adj = (u_quad_t)new_sbmax * MCLBYTES / (MSIZE + MCLBYTES);
	splx(s);

	return (0);
}

int
soreserve(struct socket *so, u_long sndcc, u_long rcvcc)
{
	KASSERT(so->so_pcb == NULL || solocked(so));

	/*
	 * there's at least one application (a configure script of screen)
	 * which expects a fifo is writable even if it has "some" bytes
	 * in its buffer.
	 * so we want to make sure (hiwat - lowat) >= (some bytes).
	 *
	 * PIPE_BUF here is an arbitrary value chosen as (some bytes) above.
	 * we expect it's large enough for such applications.
	 */
	u_long  lowat = MAX(sock_loan_thresh, MCLBYTES);
	u_long  hiwat = lowat + PIPE_BUF;

	if (sndcc < hiwat)
		sndcc = hiwat;
	if (sbreserve(&so->so_snd, sndcc, so) == 0)
		goto bad;
	if (sbreserve(&so->so_rcv, rcvcc, so) == 0)
		goto bad2;
	if (so->so_rcv.sb_lowat == 0)
		so->so_rcv.sb_lowat = 1;
	if (so->so_snd.sb_lowat == 0)
		so->so_snd.sb_lowat = lowat;
	if (so->so_snd.sb_lowat > so->so_snd.sb_hiwat)
		so->so_snd.sb_lowat = so->so_snd.sb_hiwat;
	return (0);
 bad2:
	sbrelease(&so->so_snd, so);
 bad:
	return (ENOBUFS);
}

/*
 * Allot mbufs to a sockbuf.
 * Attempt to scale mbmax so that mbcnt doesn't become limiting
 * if buffering efficiency is near the normal case.
 */
int
sbreserve(struct sockbuf *sb, u_long cc, struct socket *so)
{
	struct lwp *l = curlwp; /* XXX */
	rlim_t maxcc;
	struct uidinfo *uidinfo;

	KASSERT(so->so_pcb == NULL || solocked(so));
	KASSERT(sb->sb_so == so);
	KASSERT(sb_max_adj != 0);

	if (cc == 0 || cc > sb_max_adj)
		return (0);

	maxcc = l->l_proc->p_rlimit[RLIMIT_SBSIZE].rlim_cur;

	uidinfo = so->so_uidinfo;
	if (!chgsbsize(uidinfo, &sb->sb_hiwat, cc, maxcc))
		return 0;
	sb->sb_mbmax = uimin(cc * 2, sb_max);
	if (sb->sb_lowat > sb->sb_hiwat)
		sb->sb_lowat = sb->sb_hiwat;

	return (1);
}

/*
 * Free mbufs held by a socket, and reserved mbuf space.  We do not assert
 * that the socket is held locked here: see sorflush().
 */
void
sbrelease(struct sockbuf *sb, struct socket *so)
{

	KASSERT(sb->sb_so == so);

	sbflush(sb);
	(void)chgsbsize(so->so_uidinfo, &sb->sb_hiwat, 0, RLIM_INFINITY);
	sb->sb_mbmax = 0;
}

/*
 * Routines to add and remove
 * data from an mbuf queue.
 *
 * The routines sbappend() or sbappendrecord() are normally called to
 * append new mbufs to a socket buffer, after checking that adequate
 * space is available, comparing the function sbspace() with the amount
 * of data to be added.  sbappendrecord() differs from sbappend() in
 * that data supplied is treated as the beginning of a new record.
 * To place a sender's address, optional access rights, and data in a
 * socket receive buffer, sbappendaddr() should be used.  To place
 * access rights and data in a socket receive buffer, sbappendrights()
 * should be used.  In either case, the new data begins a new record.
 * Note that unlike sbappend() and sbappendrecord(), these routines check
 * for the caller that there will be enough space to store the data.
 * Each fails if there is not enough space, or if it cannot find mbufs
 * to store additional information in.
 *
 * Reliable protocols may use the socket send buffer to hold data
 * awaiting acknowledgement.  Data is normally copied from a socket
 * send buffer in a protocol with m_copym for output to a peer,
 * and then removing the data from the socket buffer with sbdrop()
 * or sbdroprecord() when the data is acknowledged by the peer.
 */

#ifdef SOCKBUF_DEBUG
void
sblastrecordchk(struct sockbuf *sb, const char *where)
{
	struct mbuf *m = sb->sb_mb;

	KASSERT(solocked(sb->sb_so));

	while (m && m->m_nextpkt)
		m = m->m_nextpkt;

	if (m != sb->sb_lastrecord) {
		printf("sblastrecordchk: sb_mb %p sb_lastrecord %p last %p\n",
		    sb->sb_mb, sb->sb_lastrecord, m);
		printf("packet chain:\n");
		for (m = sb->sb_mb; m != NULL; m = m->m_nextpkt)
			printf("\t%p\n", m);
		panic("sblastrecordchk from %s", where);
	}
}

void
sblastmbufchk(struct sockbuf *sb, const char *where)
{
	struct mbuf *m = sb->sb_mb;
	struct mbuf *n;

	KASSERT(solocked(sb->sb_so));

	while (m && m->m_nextpkt)
		m = m->m_nextpkt;

	while (m && m->m_next)
		m = m->m_next;

	if (m != sb->sb_mbtail) {
		printf("sblastmbufchk: sb_mb %p sb_mbtail %p last %p\n",
		    sb->sb_mb, sb->sb_mbtail, m);
		printf("packet tree:\n");
		for (m = sb->sb_mb; m != NULL; m = m->m_nextpkt) {
			printf("\t");
			for (n = m; n != NULL; n = n->m_next)
				printf("%p ", n);
			printf("\n");
		}
		panic("sblastmbufchk from %s", where);
	}
}
#endif /* SOCKBUF_DEBUG */

/*
 * Link a chain of records onto a socket buffer
 */
#define	SBLINKRECORDCHAIN(sb, m0, mlast)				\
do {									\
	if ((sb)->sb_lastrecord != NULL)				\
		(sb)->sb_lastrecord->m_nextpkt = (m0);			\
	else								\
		(sb)->sb_mb = (m0);					\
	(sb)->sb_lastrecord = (mlast);					\
} while (/*CONSTCOND*/0)


#define	SBLINKRECORD(sb, m0)						\
    SBLINKRECORDCHAIN(sb, m0, m0)

/*
 * Append mbuf chain m to the last record in the
 * socket buffer sb.  The additional space associated
 * the mbuf chain is recorded in sb.  Empty mbufs are
 * discarded and mbufs are compacted where possible.
 */
void
sbappend(struct sockbuf *sb, struct mbuf *m)
{
	struct mbuf	*n;

	KASSERT(solocked(sb->sb_so));

	if (m == NULL)
		return;

#ifdef MBUFTRACE
	m_claimm(m, sb->sb_mowner);
#endif

	SBLASTRECORDCHK(sb, "sbappend 1");

	if ((n = sb->sb_lastrecord) != NULL) {
		/*
		 * XXX Would like to simply use sb_mbtail here, but
		 * XXX I need to verify that I won't miss an EOR that
		 * XXX way.
		 */
		do {
			if (n->m_flags & M_EOR) {
				sbappendrecord(sb, m); /* XXXXXX!!!! */
				return;
			}
		} while (n->m_next && (n = n->m_next));
	} else {
		/*
		 * If this is the first record in the socket buffer, it's
		 * also the last record.
		 */
		sb->sb_lastrecord = m;
	}
	sbcompress(sb, m, n);
	SBLASTRECORDCHK(sb, "sbappend 2");
}

/*
 * This version of sbappend() should only be used when the caller
 * absolutely knows that there will never be more than one record
 * in the socket buffer, that is, a stream protocol (such as TCP).
 */
void
sbappendstream(struct sockbuf *sb, struct mbuf *m)
{

	KASSERT(solocked(sb->sb_so));
	KDASSERT(m->m_nextpkt == NULL);
	KASSERT(sb->sb_mb == sb->sb_lastrecord);

	SBLASTMBUFCHK(sb, __func__);

#ifdef MBUFTRACE
	m_claimm(m, sb->sb_mowner);
#endif

	sbcompress(sb, m, sb->sb_mbtail);

	sb->sb_lastrecord = sb->sb_mb;
	SBLASTRECORDCHK(sb, __func__);
}

#ifdef SOCKBUF_DEBUG
void
sbcheck(struct sockbuf *sb)
{
	struct mbuf	*m, *m2;
	u_long		len, mbcnt;

	KASSERT(solocked(sb->sb_so));

	len = 0;
	mbcnt = 0;
	for (m = sb->sb_mb; m; m = m->m_nextpkt) {
		for (m2 = m; m2 != NULL; m2 = m2->m_next) {
			len += m2->m_len;
			mbcnt += MSIZE;
			if (m2->m_flags & M_EXT)
				mbcnt += m2->m_ext.ext_size;
			if (m2->m_nextpkt != NULL)
				panic("sbcheck nextpkt");
		}
	}
	if (len != sb->sb_cc || mbcnt != sb->sb_mbcnt) {
		printf("cc %lu != %lu || mbcnt %lu != %lu\n", len, sb->sb_cc,
		    mbcnt, sb->sb_mbcnt);
		panic("sbcheck");
	}
}
#endif

/*
 * As above, except the mbuf chain
 * begins a new record.
 */
void
sbappendrecord(struct sockbuf *sb, struct mbuf *m0)
{
	struct mbuf	*m;

	KASSERT(solocked(sb->sb_so));

	if (m0 == NULL)
		return;

#ifdef MBUFTRACE
	m_claimm(m0, sb->sb_mowner);
#endif
	/*
	 * Put the first mbuf on the queue.
	 * Note this permits zero length records.
	 */
	sballoc(sb, m0);
	SBLASTRECORDCHK(sb, "sbappendrecord 1");
	SBLINKRECORD(sb, m0);
	m = m0->m_next;
	m0->m_next = 0;
	if (m && (m0->m_flags & M_EOR)) {
		m0->m_flags &= ~M_EOR;
		m->m_flags |= M_EOR;
	}
	sbcompress(sb, m, m0);
	SBLASTRECORDCHK(sb, "sbappendrecord 2");
}

/*
 * As above except that OOB data
 * is inserted at the beginning of the sockbuf,
 * but after any other OOB data.
 */
void
sbinsertoob(struct sockbuf *sb, struct mbuf *m0)
{
	struct mbuf	*m, **mp;

	KASSERT(solocked(sb->sb_so));

	if (m0 == NULL)
		return;

	SBLASTRECORDCHK(sb, "sbinsertoob 1");

	for (mp = &sb->sb_mb; (m = *mp) != NULL; mp = &((*mp)->m_nextpkt)) {
	    again:
		switch (m->m_type) {

		case MT_OOBDATA:
			continue;		/* WANT next train */

		case MT_CONTROL:
			if ((m = m->m_next) != NULL)
				goto again;	/* inspect THIS train further */
		}
		break;
	}
	/*
	 * Put the first mbuf on the queue.
	 * Note this permits zero length records.
	 */
	sballoc(sb, m0);
	m0->m_nextpkt = *mp;
	if (*mp == NULL) {
		/* m0 is actually the new tail */
		sb->sb_lastrecord = m0;
	}
	*mp = m0;
	m = m0->m_next;
	m0->m_next = 0;
	if (m && (m0->m_flags & M_EOR)) {
		m0->m_flags &= ~M_EOR;
		m->m_flags |= M_EOR;
	}
	sbcompress(sb, m, m0);
	SBLASTRECORDCHK(sb, "sbinsertoob 2");
}

/*
 * Append address and data, and optionally, control (ancillary) data
 * to the receive queue of a socket.  If present,
 * m0 must include a packet header with total length.
 * Returns 0 if no space in sockbuf or insufficient mbufs.
 */
int
sbappendaddr(struct sockbuf *sb, const struct sockaddr *asa, struct mbuf *m0,
	struct mbuf *control)
{
	struct mbuf	*m, *n, *nlast;
	int		space, len;

	KASSERT(solocked(sb->sb_so));

	space = asa->sa_len;

	if (m0 != NULL) {
		if ((m0->m_flags & M_PKTHDR) == 0)
			panic("sbappendaddr");
		space += m0->m_pkthdr.len;
#ifdef MBUFTRACE
		m_claimm(m0, sb->sb_mowner);
#endif
	}
	for (n = control; n; n = n->m_next) {
		space += n->m_len;
		MCLAIM(n, sb->sb_mowner);
		if (n->m_next == NULL)	/* keep pointer to last control buf */
			break;
	}
	if (space > sbspace(sb))
		return (0);
	m = m_get(M_DONTWAIT, MT_SONAME);
	if (m == NULL)
		return (0);
	MCLAIM(m, sb->sb_mowner);
	/*
	 * XXX avoid 'comparison always true' warning which isn't easily
	 * avoided.
	 */
	len = asa->sa_len;
	if (len > MLEN) {
		MEXTMALLOC(m, asa->sa_len, M_NOWAIT);
		if ((m->m_flags & M_EXT) == 0) {
			m_free(m);
			return (0);
		}
	}
	m->m_len = asa->sa_len;
	memcpy(mtod(m, void *), asa, asa->sa_len);
	if (n)
		n->m_next = m0;		/* concatenate data to control */
	else
		control = m0;
	m->m_next = control;

	SBLASTRECORDCHK(sb, "sbappendaddr 1");

	for (n = m; n->m_next != NULL; n = n->m_next)
		sballoc(sb, n);
	sballoc(sb, n);
	nlast = n;
	SBLINKRECORD(sb, m);

	sb->sb_mbtail = nlast;
	SBLASTMBUFCHK(sb, "sbappendaddr");
	SBLASTRECORDCHK(sb, "sbappendaddr 2");

	return (1);
}

/*
 * Helper for sbappendchainaddr: prepend a struct sockaddr* to
 * an mbuf chain.
 */
static inline struct mbuf *
m_prepend_sockaddr(struct sockbuf *sb, struct mbuf *m0,
		   const struct sockaddr *asa)
{
	struct mbuf *m;
	const int salen = asa->sa_len;

	KASSERT(solocked(sb->sb_so));

	/* only the first in each chain need be a pkthdr */
	m = m_gethdr(M_DONTWAIT, MT_SONAME);
	if (m == NULL)
		return NULL;
	MCLAIM(m, sb->sb_mowner);
#ifdef notyet
	if (salen > MHLEN) {
		MEXTMALLOC(m, salen, M_NOWAIT);
		if ((m->m_flags & M_EXT) == 0) {
			m_free(m);
			return NULL;
		}
	}
#else
	KASSERT(salen <= MHLEN);
#endif
	m->m_len = salen;
	memcpy(mtod(m, void *), asa, salen);
	m->m_next = m0;
	m->m_pkthdr.len = salen + m0->m_pkthdr.len;

	return m;
}

int
sbappendaddrchain(struct sockbuf *sb, const struct sockaddr *asa,
		  struct mbuf *m0, int sbprio)
{
	struct mbuf *m, *n, *n0, *nlast;
	int error;

	KASSERT(solocked(sb->sb_so));

	/*
	 * XXX sbprio reserved for encoding priority of this* request:
	 *  SB_PRIO_NONE --> honour normal sb limits
	 *  SB_PRIO_ONESHOT_OVERFLOW --> if socket has any space,
	 *	take whole chain. Intended for large requests
	 *      that should be delivered atomically (all, or none).
	 * SB_PRIO_OVERDRAFT -- allow a small (2*MLEN) overflow
	 *       over normal socket limits, for messages indicating
	 *       buffer overflow in earlier normal/lower-priority messages
	 * SB_PRIO_BESTEFFORT -->  ignore limits entirely.
	 *       Intended for  kernel-generated messages only.
	 *        Up to generator to avoid total mbuf resource exhaustion.
	 */
	(void)sbprio;

	if (m0 && (m0->m_flags & M_PKTHDR) == 0)
		panic("sbappendaddrchain");

#ifdef notyet
	space = sbspace(sb);

	/*
	 * Enforce SB_PRIO_* limits as described above.
	 */
#endif

	n0 = NULL;
	nlast = NULL;
	for (m = m0; m; m = m->m_nextpkt) {
		struct mbuf *np;

#ifdef MBUFTRACE
		m_claimm(m, sb->sb_mowner);
#endif

		/* Prepend sockaddr to this record (m) of input chain m0 */
	  	n = m_prepend_sockaddr(sb, m, asa);
		if (n == NULL) {
			error = ENOBUFS;
			goto bad;
		}

		/* Append record (asa+m) to end of new chain n0 */
		if (n0 == NULL) {
			n0 = n;
		} else {
			nlast->m_nextpkt = n;
		}
		/* Keep track of last record on new chain */
		nlast = n;

		for (np = n; np; np = np->m_next)
			sballoc(sb, np);
	}

	SBLASTRECORDCHK(sb, "sbappendaddrchain 1");

	/* Drop the entire chain of (asa+m) records onto the socket */
	SBLINKRECORDCHAIN(sb, n0, nlast);

	SBLASTRECORDCHK(sb, "sbappendaddrchain 2");

	for (m = nlast; m->m_next; m = m->m_next)
		;
	sb->sb_mbtail = m;
	SBLASTMBUFCHK(sb, "sbappendaddrchain");

	return (1);

bad:
	/*
	 * On error, free the prepended addreseses. For consistency
	 * with sbappendaddr(), leave it to our caller to free
	 * the input record chain passed to us as m0.
	 */
	while ((n = n0) != NULL) {
	  	struct mbuf *np;

		/* Undo the sballoc() of this record */
		for (np = n; np; np = np->m_next)
			sbfree(sb, np);

		n0 = n->m_nextpkt;	/* iterate at next prepended address */
		np = m_free(n);		/* free prepended address (not data) */
	}
	return error;
}


int
sbappendcontrol(struct sockbuf *sb, struct mbuf *m0, struct mbuf *control)
{
	struct mbuf	*m, *mlast, *n;
	int		space;

	KASSERT(solocked(sb->sb_so));

	space = 0;
	if (control == NULL)
		panic("sbappendcontrol");
	for (m = control; ; m = m->m_next) {
		space += m->m_len;
		MCLAIM(m, sb->sb_mowner);
		if (m->m_next == NULL)
			break;
	}
	n = m;			/* save pointer to last control buffer */
	for (m = m0; m; m = m->m_next) {
		MCLAIM(m, sb->sb_mowner);
		space += m->m_len;
	}
	if (space > sbspace(sb))
		return (0);
	n->m_next = m0;			/* concatenate data to control */

	SBLASTRECORDCHK(sb, "sbappendcontrol 1");

	for (m = control; m->m_next != NULL; m = m->m_next)
		sballoc(sb, m);
	sballoc(sb, m);
	mlast = m;
	SBLINKRECORD(sb, control);

	sb->sb_mbtail = mlast;
	SBLASTMBUFCHK(sb, "sbappendcontrol");
	SBLASTRECORDCHK(sb, "sbappendcontrol 2");

	return (1);
}

/*
 * Compress mbuf chain m into the socket
 * buffer sb following mbuf n.  If n
 * is null, the buffer is presumed empty.
 */
void
sbcompress(struct sockbuf *sb, struct mbuf *m, struct mbuf *n)
{
	int		eor;
	struct mbuf	*o;

	KASSERT(solocked(sb->sb_so));

	eor = 0;
	while (m) {
		eor |= m->m_flags & M_EOR;
		if (m->m_len == 0 &&
		    (eor == 0 ||
		     (((o = m->m_next) || (o = n)) &&
		      o->m_type == m->m_type))) {
			if (sb->sb_lastrecord == m)
				sb->sb_lastrecord = m->m_next;
			m = m_free(m);
			continue;
		}
		if (n && (n->m_flags & M_EOR) == 0 &&
		    /* M_TRAILINGSPACE() checks buffer writeability */
		    m->m_len <= MCLBYTES / 4 && /* XXX Don't copy too much */
		    m->m_len <= M_TRAILINGSPACE(n) &&
		    n->m_type == m->m_type) {
			memcpy(mtod(n, char *) + n->m_len, mtod(m, void *),
			    (unsigned)m->m_len);
			n->m_len += m->m_len;
			sb->sb_cc += m->m_len;
			m = m_free(m);
			continue;
		}
		if (n)
			n->m_next = m;
		else
			sb->sb_mb = m;
		sb->sb_mbtail = m;
		sballoc(sb, m);
		n = m;
		m->m_flags &= ~M_EOR;
		m = m->m_next;
		n->m_next = 0;
	}
	if (eor) {
		if (n)
			n->m_flags |= eor;
		else
			printf("semi-panic: sbcompress\n");
	}
	SBLASTMBUFCHK(sb, __func__);
}

/*
 * Free all mbufs in a sockbuf.
 * Check that all resources are reclaimed.
 */
void
sbflush(struct sockbuf *sb)
{

	KASSERT(solocked(sb->sb_so));
	KASSERT((sb->sb_flags & SB_LOCK) == 0);

	while (sb->sb_mbcnt)
		sbdrop(sb, (int)sb->sb_cc);

	KASSERT(sb->sb_cc == 0);
	KASSERT(sb->sb_mb == NULL);
	KASSERT(sb->sb_mbtail == NULL);
	KASSERT(sb->sb_lastrecord == NULL);
}

/*
 * Drop data from (the front of) a sockbuf.
 */
void
sbdrop(struct sockbuf *sb, int len)
{
	struct mbuf	*m, *next;

	KASSERT(solocked(sb->sb_so));

	next = (m = sb->sb_mb) ? m->m_nextpkt : NULL;
	while (len > 0) {
		if (m == NULL) {
			if (next == NULL)
				panic("sbdrop(%p,%d): cc=%lu",
				    sb, len, sb->sb_cc);
			m = next;
			next = m->m_nextpkt;
			continue;
		}
		if (m->m_len > len) {
			m->m_len -= len;
			m->m_data += len;
			sb->sb_cc -= len;
			break;
		}
		len -= m->m_len;
		sbfree(sb, m);
		m = m_free(m);
	}
	while (m && m->m_len == 0) {
		sbfree(sb, m);
		m = m_free(m);
	}
	if (m) {
		sb->sb_mb = m;
		m->m_nextpkt = next;
	} else
		sb->sb_mb = next;
	/*
	 * First part is an inline SB_EMPTY_FIXUP().  Second part
	 * makes sure sb_lastrecord is up-to-date if we dropped
	 * part of the last record.
	 */
	m = sb->sb_mb;
	if (m == NULL) {
		sb->sb_mbtail = NULL;
		sb->sb_lastrecord = NULL;
	} else if (m->m_nextpkt == NULL)
		sb->sb_lastrecord = m;
}

/*
 * Drop a record off the front of a sockbuf
 * and move the next record to the front.
 */
void
sbdroprecord(struct sockbuf *sb)
{
	struct mbuf	*m, *mn;

	KASSERT(solocked(sb->sb_so));

	m = sb->sb_mb;
	if (m) {
		sb->sb_mb = m->m_nextpkt;
		do {
			sbfree(sb, m);
			mn = m_free(m);
		} while ((m = mn) != NULL);
	}
	SB_EMPTY_FIXUP(sb);
}

/*
 * Create a "control" mbuf containing the specified data
 * with the specified type for presentation on a socket buffer.
 */
struct mbuf *
sbcreatecontrol1(void **p, int size, int type, int level, int flags)
{
	struct cmsghdr	*cp;
	struct mbuf	*m;
	int space = CMSG_SPACE(size);

	if ((flags & M_DONTWAIT) && space > MCLBYTES) {
		printf("%s: message too large %d\n", __func__, space);
		return NULL;
	}

	if ((m = m_get(flags, MT_CONTROL)) == NULL)
		return NULL;
	if (space > MLEN) {
		if (space > MCLBYTES)
			MEXTMALLOC(m, space, M_WAITOK);
		else
			MCLGET(m, flags);
		if ((m->m_flags & M_EXT) == 0) {
			m_free(m);
			return NULL;
		}
	}
	cp = mtod(m, struct cmsghdr *);
	*p = CMSG_DATA(cp);
	m->m_len = space;
	cp->cmsg_len = CMSG_LEN(size);
	cp->cmsg_level = level;
	cp->cmsg_type = type;

	memset(cp + 1, 0, CMSG_LEN(0) - sizeof(*cp));
	memset((uint8_t *)*p + size, 0, CMSG_ALIGN(size) - size);

	return m;
}

struct mbuf *
sbcreatecontrol(void *p, int size, int type, int level)
{
	struct mbuf *m;
	void *v;

	m = sbcreatecontrol1(&v, size, type, level, M_DONTWAIT);
	if (m == NULL)
		return NULL;
	memcpy(v, p, size);
	return m;
}

void
solockretry(struct socket *so, kmutex_t *lock)
{

	while (lock != atomic_load_relaxed(&so->so_lock)) {
		mutex_exit(lock);
		lock = atomic_load_consume(&so->so_lock);
		mutex_enter(lock);
	}
}

bool
solocked(const struct socket *so)
{

	/*
	 * Used only for diagnostic assertions, so so_lock should be
	 * stable at this point, hence on need for atomic_load_*.
	 */
	return mutex_owned(so->so_lock);
}

bool
solocked2(const struct socket *so1, const struct socket *so2)
{
	const kmutex_t *lock;

	/*
	 * Used only for diagnostic assertions, so so_lock should be
	 * stable at this point, hence on need for atomic_load_*.
	 */
	lock = so1->so_lock;
	if (lock != so2->so_lock)
		return false;
	return mutex_owned(lock);
}

/*
 * sosetlock: assign a default lock to a new socket.
 */
void
sosetlock(struct socket *so)
{
	if (so->so_lock == NULL) {
		kmutex_t *lock = softnet_lock;

		so->so_lock = lock;
		mutex_obj_hold(lock);
		mutex_enter(lock);
	}
	KASSERT(solocked(so));
}

/*
 * Set lock on sockbuf sb; sleep if lock is already held.
 * Unless SB_NOINTR is set on sockbuf, sleep is interruptible.
 * Returns error without lock if sleep is interrupted.
 */
int
sblock(struct sockbuf *sb, int wf)
{
	struct socket *so;
	kmutex_t *lock;
	int error;

	KASSERT(solocked(sb->sb_so));

	for (;;) {
		if (__predict_true((sb->sb_flags & SB_LOCK) == 0)) {
			sb->sb_flags |= SB_LOCK;
			return 0;
		}
		if (wf != M_WAITOK)
			return EWOULDBLOCK;
		so = sb->sb_so;
		lock = so->so_lock;
		if ((sb->sb_flags & SB_NOINTR) != 0) {
			cv_wait(&so->so_cv, lock);
			error = 0;
		} else
			error = cv_wait_sig(&so->so_cv, lock);
		if (__predict_false(lock != atomic_load_relaxed(&so->so_lock)))
			solockretry(so, lock);
		if (error != 0)
			return error;
	}
}

void
sbunlock(struct sockbuf *sb)
{
	struct socket *so;

	so = sb->sb_so;

	KASSERT(solocked(so));
	KASSERT((sb->sb_flags & SB_LOCK) != 0);

	sb->sb_flags &= ~SB_LOCK;
	cv_broadcast(&so->so_cv);
}

int
sowait(struct socket *so, bool catch_p, int timo)
{
	kmutex_t *lock;
	int error;

	KASSERT(solocked(so));
	KASSERT(catch_p || timo != 0);

	lock = so->so_lock;
	if (catch_p)
		error = cv_timedwait_sig(&so->so_cv, lock, timo);
	else
		error = cv_timedwait(&so->so_cv, lock, timo);
	if (__predict_false(lock != atomic_load_relaxed(&so->so_lock)))
		solockretry(so, lock);
	return error;
}

#ifdef DDB

/*
 * Currently, sofindproc() is used only from DDB. It could be used from others
 * by using db_mutex_enter()
 */

static inline int
db_mutex_enter(kmutex_t *mtx)
{
	int rv;

	if (!db_active) {
		mutex_enter(mtx);
		rv = 1;
	} else
		rv = mutex_tryenter(mtx);

	return rv;
}

int
sofindproc(struct socket *so, int all, void (*pr)(const char *, ...))
{
	proc_t *p;
	filedesc_t *fdp;
	fdtab_t *dt;
	fdfile_t *ff;
	file_t *fp = NULL;
	int found = 0;
	int i, t;

	if (so == NULL)
		return 0;

	t = db_mutex_enter(&proc_lock);
	if (!t) {
		pr("could not acquire proc_lock mutex\n");
		return 0;
	}
	PROCLIST_FOREACH(p, &allproc) {
		if (p->p_stat == SIDL)
			continue;
		fdp = p->p_fd;
		t = db_mutex_enter(&fdp->fd_lock);
		if (!t) {
			pr("could not acquire fd_lock mutex\n");
			continue;
		}
		dt = atomic_load_consume(&fdp->fd_dt);
		for (i = 0; i < dt->dt_nfiles; i++) {
			ff = dt->dt_ff[i];
			if (ff == NULL)
				continue;

			fp = atomic_load_consume(&ff->ff_file);
			if (fp == NULL)
				continue;

			t = db_mutex_enter(&fp->f_lock);
			if (!t) {
				pr("could not acquire f_lock mutex\n");
				continue;
			}
			if ((struct socket *)fp->f_data != so) {
				mutex_exit(&fp->f_lock);
				continue;
			}
			found++;
			if (pr)
				pr("socket %p: owner %s(pid=%d)\n",
				    so, p->p_comm, p->p_pid);
			mutex_exit(&fp->f_lock);
			if (all == 0)
				break;
		}
		mutex_exit(&fdp->fd_lock);
		if (all == 0 && found != 0)
			break;
	}
	mutex_exit(&proc_lock);

	return found;
}

void
socket_print(const char *modif, void (*pr)(const char *, ...))
{
	file_t *fp;
	struct socket *so;
	struct sockbuf *sb_snd, *sb_rcv;
	struct mbuf *m_rec, *m;
	bool opt_v = false;
	bool opt_m = false;
	bool opt_a = false;
	bool opt_p = false;
	int nrecs, nmbufs;
	char ch;
	const char *family;

	while ( (ch = *(modif++)) != '\0') {
		switch (ch) {
		case 'v':
			opt_v = true;
			break;
		case 'm':
			opt_m = true;
			break;
		case 'a':
			opt_a = true;
			break;
		case 'p':
			opt_p = true;
			break;
		}
	}
	if (opt_v == false && pr)
		(pr)("Ignore empty sockets. use /v to print all.\n");
	if (opt_p == true && pr)
		(pr)("Don't search owner process.\n");

	LIST_FOREACH(fp, &filehead, f_list) {
		if (fp->f_type != DTYPE_SOCKET)
			continue;
		so = (struct socket *)fp->f_data;
		if (so == NULL)
			continue;

		if (so->so_proto->pr_domain->dom_family == AF_INET)
			family = "INET";
#ifdef INET6
		else if (so->so_proto->pr_domain->dom_family == AF_INET6)
			family = "INET6";
#endif
		else if (so->so_proto->pr_domain->dom_family == pseudo_AF_KEY)
			family = "KEY";
		else if (so->so_proto->pr_domain->dom_family == AF_ROUTE)
			family = "ROUTE";
		else
			continue;

		sb_snd = &so->so_snd;
		sb_rcv = &so->so_rcv;

		if (opt_v != true &&
		    sb_snd->sb_cc == 0 && sb_rcv->sb_cc == 0)
			continue;

		pr("---SOCKET %p: type %s\n", so, family);
		if (opt_p != true)
			sofindproc(so, opt_a == true ? 1 : 0, pr);
		pr("Send Buffer Bytes: %d [bytes]\n", sb_snd->sb_cc);
		pr("Send Buffer mbufs:\n");
		m_rec = m = sb_snd->sb_mb;
		nrecs = 0;
		nmbufs = 0;
		while (m_rec) {
			nrecs++;
			if (opt_m == true)
				pr(" mbuf chain %p\n", m_rec);
			while (m) {
				nmbufs++;
				m = m->m_next;
			}
			m_rec = m = m_rec->m_nextpkt;
		}
		pr(" Total %d records, %d mbufs.\n", nrecs, nmbufs);

		pr("Recv Buffer Usage: %d [bytes]\n", sb_rcv->sb_cc);
		pr("Recv Buffer mbufs:\n");
		m_rec = m = sb_rcv->sb_mb;
		nrecs = 0;
		nmbufs = 0;
		while (m_rec) {
			nrecs++;
			if (opt_m == true)
				pr(" mbuf chain %p\n", m_rec);
			while (m) {
				nmbufs++;
				m = m->m_next;
			}
			m_rec = m = m_rec->m_nextpkt;
		}
		pr(" Total %d records, %d mbufs.\n", nrecs, nmbufs);
	}
}
#endif /* DDB */