summaryrefslogtreecommitdiffstats
path: root/unix/tclUnixSock.c
blob: 78ed008e998fa3590e608fdb2ea1cc4282a694df (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
/*
 * tclUnixSock.c --
 *
 *	This file contains Unix-specific socket related code.
 *
 * Copyright © 1995 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 */

#include "tclInt.h"
#include <netinet/tcp.h>

/*
 * Helper macros to make parts of this file clearer. The macros do exactly
 * what they say on the tin. :-) They also only ever refer to their arguments
 * once, and so can be used without regard to side effects.
 */

#define SET_BITS(var, bits)	((var) |= (bits))
#define CLEAR_BITS(var, bits)	((var) &= ~(bits))
#define GOT_BITS(var, bits)     (((var) & (bits)) != 0)

/* "sock" + a pointer in hex + \0 */
#define SOCK_CHAN_LENGTH        (4 + sizeof(void *) * 2 + 1)
#define SOCK_TEMPLATE           "sock%" TCL_Z_MODIFIER "x"

#undef SOCKET   /* Possible conflict with win32 SOCKET */

/*
 * This is needed to comply with the strict aliasing rules of GCC, but it also
 * simplifies casting between the different sockaddr types.
 */

typedef union {
    struct sockaddr sa;
    struct sockaddr_in sa4;
    struct sockaddr_in6 sa6;
    struct sockaddr_storage sas;
} address;

/*
 * This structure describes per-instance state of a tcp-based channel.
 */

typedef struct TcpState TcpState;

typedef struct TcpFdList {
    TcpState *statePtr;
    int fd;
    struct TcpFdList *next;
} TcpFdList;

struct TcpState {
    Tcl_Channel channel;	/* Channel associated with this file. */
    int flags;			/* OR'ed combination of the bitfields defined
				 * below. */
    TcpFdList fds;		/* The file descriptors of the sockets. */
    int interest;		/* Event types of interest */

    /*
     * Only needed for server sockets
     */

    Tcl_TcpAcceptProc *acceptProc;
                                /* Proc to call on accept. */
    void *acceptProcData;  /* The data for the accept proc. */

    /*
     * Only needed for client sockets
     */

    struct addrinfo *addrlist;	/* Addresses to connect to. */
    struct addrinfo *addr;	/* Iterator over addrlist. */
    struct addrinfo *myaddrlist;/* Local address. */
    struct addrinfo *myaddr;	/* Iterator over myaddrlist. */
    int filehandlers;           /* Caches FileHandlers that get set up while
                                 * an async socket is not yet connected. */
    int connectError;           /* Cache SO_ERROR of async socket. */
    int cachedBlocking;         /* Cache blocking mode of async socket. */
};

/*
 * These bits may be OR'ed together into the "flags" field of a TcpState
 * structure.
 */

#define TCP_NONBLOCKING		(1<<0)	/* Socket with non-blocking I/O */
#define TCP_ASYNC_CONNECT	(1<<1)	/* Async connect in progress. */
#define TCP_ASYNC_PENDING	(1<<4)	/* TcpConnect was called to
					 * process an async connect. This
					 * flag indicates that reentry is
					 * still pending */
#define TCP_ASYNC_FAILED	(1<<5)	/* An async connect finally failed */

#define TCP_ASYNC_TEST_MODE	(1<<8)	/* Async testing activated.  Do not
					 * automatically continue connection
					 * process. */

/*
 * The following defines the maximum length of the listen queue. This is the
 * number of outstanding yet-to-be-serviced requests for a connection on a
 * server socket, more than this number of outstanding requests and the
 * connection request will fail.
 */

#ifndef SOMAXCONN
#   define SOMAXCONN	100
#elif (SOMAXCONN < 100)
#   undef  SOMAXCONN
#   define SOMAXCONN	100
#endif /* SOMAXCONN < 100 */

/*
 * The following defines how much buffer space the kernel should maintain for
 * a socket.
 */

#define SOCKET_BUFSIZE	4096

/*
 * Static routines for this file:
 */

static void		TcpAsyncCallback(void *clientData, int mask);
static int		TcpConnect(Tcl_Interp *interp, TcpState *state);
static void		TcpAccept(void *data, int mask);
static int		TcpBlockModeProc(void *data, int mode);
static int		TcpCloseProc(void *instanceData,
			    Tcl_Interp *interp);
static int		TcpClose2Proc(void *instanceData,
			    Tcl_Interp *interp, int flags);
static int		TcpGetHandleProc(void *instanceData,
			    int direction, void **handlePtr);
static int		TcpGetOptionProc(void *instanceData,
			    Tcl_Interp *interp, const char *optionName,
			    Tcl_DString *dsPtr);
static int		TcpInputProc(void *instanceData, char *buf,
			    int toRead, int *errorCode);
static int		TcpOutputProc(void *instanceData,
			    const char *buf, int toWrite, int *errorCode);
static int		TcpSetOptionProc(void *instanceData,
			    Tcl_Interp *interp, const char *optionName,
			    const char *value);
static void		TcpThreadActionProc(void *instanceData, int action);
static void		TcpWatchProc(void *instanceData, int mask);
static int		WaitForConnect(TcpState *statePtr, int *errorCodePtr);
static Tcl_FileProc	WrapNotify;

/*
 * This structure describes the channel type structure for TCP socket
 * based IO:
 */

static const Tcl_ChannelType tcpChannelType = {
    "tcp",			/* Type name. */
    TCL_CHANNEL_VERSION_5,	/* v5 channel */
    NULL,		/* Close proc. */
    TcpInputProc,		/* Input proc. */
    TcpOutputProc,		/* Output proc. */
    NULL,			/* Seek proc. */
    TcpSetOptionProc,		/* Set option proc. */
    TcpGetOptionProc,		/* Get option proc. */
    TcpWatchProc,		/* Initialize notifier. */
    TcpGetHandleProc,		/* Get OS handles out of channel. */
    TcpClose2Proc,		/* Close2 proc. */
    TcpBlockModeProc,		/* Set blocking or non-blocking mode.*/
    NULL,			/* flush proc. */
    NULL,			/* handler proc. */
    NULL,			/* wide seek proc. */
    TcpThreadActionProc,	/* thread action proc. */
    NULL			/* truncate proc. */
};

/*
 * The following variable holds the network name of this host.
 */

static TclInitProcessGlobalValueProc InitializeHostName;
static ProcessGlobalValue hostName =
	{0, 0, NULL, NULL, InitializeHostName, NULL, NULL};

#if 0
/* printf debugging */
void
printaddrinfo(
    struct addrinfo *addrlist,
    char *prefix)
{
    char host[NI_MAXHOST], port[NI_MAXSERV];
    struct addrinfo *ai;

    for (ai = addrlist; ai != NULL; ai = ai->ai_next) {
	getnameinfo(ai->ai_addr, ai->ai_addrlen,
		host, sizeof(host), port, sizeof(port),
		NI_NUMERICHOST|NI_NUMERICSERV);
	fprintf(stderr,"%s: %s:%s\n", prefix, host, port);
    }
}
#endif
/*
 * ----------------------------------------------------------------------
 *
 * InitializeHostName --
 *
 * 	This routine sets the process global value of the name of the local
 * 	host on which the process is running.
 *
 * Results:
 *	None.
 *
 * ----------------------------------------------------------------------
 */

static void
InitializeHostName(
    char **valuePtr,
    size_t *lengthPtr,
    Tcl_Encoding *encodingPtr)
{
    const char *native = NULL;

#ifndef NO_UNAME
    struct utsname u;
    struct hostent *hp;

    memset(&u, (int) 0, sizeof(struct utsname));
    if (uname(&u) >= 0) {				/* INTL: Native. */
        hp = TclpGetHostByName(u.nodename);		/* INTL: Native. */
	if (hp == NULL) {
	    /*
	     * Sometimes the nodename is fully qualified, but gets truncated
	     * as it exceeds SYS_NMLN. See if we can just get the immediate
	     * nodename and get a proper answer that way.
	     */

	    char *dot = strchr(u.nodename, '.');

	    if (dot != NULL) {
		char *node = (char *)Tcl_Alloc(dot - u.nodename + 1);

		memcpy(node, u.nodename, dot - u.nodename);
		node[dot - u.nodename] = '\0';
		hp = TclpGetHostByName(node);
		Tcl_Free(node);
	    }
	}
        if (hp != NULL) {
	    native = hp->h_name;
        } else {
	    native = u.nodename;
        }
    }
#else /* !NO_UNAME */
    /*
     * Uname doesn't exist; try gethostname instead.
     *
     * There is no portable macro for the maximum length of host names
     * returned by gethostbyname(). We should only trust SYS_NMLN if it is at
     * least 255 + 1 bytes to comply with DNS host name limits.
     *
     * Note: SYS_NMLN is a restriction on "uname" not on gethostbyname!
     *
     * For example HP-UX 10.20 has SYS_NMLN == 9, while gethostbyname() can
     * return a fully qualified name from DNS of up to 255 bytes.
     *
     * Fix suggested by Viktor Dukhovni (viktor@esm.com)
     */

#    if defined(SYS_NMLN) && (SYS_NMLEN >= 256)
    char buffer[SYS_NMLEN];
#    else
    char buffer[256];
#    endif

    if (gethostname(buffer, sizeof(buffer)) >= 0) {	/* INTL: Native. */
	native = buffer;
    }
#endif /* NO_UNAME */

    *encodingPtr = Tcl_GetEncoding(NULL, NULL);
    if (native) {
	*lengthPtr = strlen(native);
	*valuePtr = (char *)Tcl_Alloc(*lengthPtr + 1);
	memcpy(*valuePtr, native, *lengthPtr + 1);
    } else {
	*lengthPtr = 0;
	*valuePtr = (char *)Tcl_Alloc(1);
	*valuePtr[0] = '\0';
    }
}

/*
 * ----------------------------------------------------------------------
 *
 * Tcl_GetHostName --
 *
 *	Returns the name of the local host.
 *
 * Results:
 *	A string containing the network name for this machine, or an empty
 *	string if we can't figure out the name. The caller must not modify or
 *	free this string.
 *
 * Side effects:
 *	Caches the name to return for future calls.
 *
 * ----------------------------------------------------------------------
 */

const char *
Tcl_GetHostName(void)
{
    Tcl_Obj *tclObj = TclGetProcessGlobalValue(&hostName);
    return TclGetString(tclObj);
}

/*
 * ----------------------------------------------------------------------
 *
 * TclpFinalizeSockets --
 *
 *	Performs per-thread socket subsystem finalization.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 * ----------------------------------------------------------------------
 */

void
TclpFinalizeSockets(void)
{
    return;
}

/*
 * ----------------------------------------------------------------------
 *
 * TcpBlockModeProc --
 *
 *	This function is invoked by the generic IO level to set blocking and
 *	nonblocking mode on a TCP socket based channel.
 *
 * Results:
 *	0 if successful, errno when failed.
 *
 * Side effects:
 *	Sets the device into blocking or nonblocking mode.
 *
 * ----------------------------------------------------------------------
 */

static int
TcpBlockModeProc(
    void *instanceData,	/* Socket state. */
    int mode)			/* The mode to set. Can be one of
				 * TCL_MODE_BLOCKING or
				 * TCL_MODE_NONBLOCKING. */
{
    TcpState *statePtr = (TcpState *)instanceData;

    if (mode == TCL_MODE_BLOCKING) {
	CLEAR_BITS(statePtr->flags, TCP_NONBLOCKING);
    } else {
	SET_BITS(statePtr->flags, TCP_NONBLOCKING);
    }
    if (GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT)) {
        statePtr->cachedBlocking = mode;
        return 0;
    }
    if (TclUnixSetBlockingMode(statePtr->fds.fd, mode) < 0) {
	return errno;
    }
    return 0;
}

/*
 * ----------------------------------------------------------------------
 *
 * WaitForConnect --
 *
 *	Check the state of an async connect process. If a connection attempt
 *	terminated, process it, which may finalize it or may start the next
 *	attempt. If a connect error occurs, it is saved in
 *	statePtr->connectError to be reported by 'fconfigure -error'.
 *
 *	There are two modes of operation, defined by errorCodePtr:
 *	 *  non-NULL: Called by explicit read/write command. Blocks if the
 *	    socket is blocking.
 *	    May return two error codes:
 *	     *	EWOULDBLOCK: if connect is still in progress
 *	     *	ENOTCONN: if connect failed. This would be the error message
 *		of a recv or sendto syscall so this is emulated here.
 *	 *  NULL: Called by a background operation. Do not block and do not
 *	    return any error code.
 *
 * Results:
 * 	0 if the connection has completed, -1 if still in progress or there is
 * 	an error.
 *
 * Side effects:
 *	Processes socket events off the system queue. May process
 *	asynchronous connects.
 *
 *----------------------------------------------------------------------
 */

static int
WaitForConnect(
    TcpState *statePtr,		/* State of the socket. */
    int *errorCodePtr)
{
    int timeout;

    /*
     * Check if an async connect failed already and error reporting is
     * demanded, return the error ENOTCONN
     */

    if (errorCodePtr != NULL && GOT_BITS(statePtr->flags, TCP_ASYNC_FAILED)) {
	*errorCodePtr = ENOTCONN;
	return -1;
    }

    /*
     * Check if an async connect is running. If not return ok.
     */

    if (!GOT_BITS(statePtr->flags, TCP_ASYNC_PENDING)) {
	return 0;
    }

    /*
     * In socket test mode do not continue with the connect.
     * Exceptions are:
     * - Call by recv/send and blocking socket
     *   (errorCodePtr != NULL && !GOT_BITS(flags, TCP_NONBLOCKING))
     */

    if (GOT_BITS(statePtr->flags, TCP_ASYNC_TEST_MODE)
            && !(errorCodePtr != NULL
                    && !GOT_BITS(statePtr->flags, TCP_NONBLOCKING))) {
	*errorCodePtr = EWOULDBLOCK;
	return -1;
    }

    if (errorCodePtr == NULL || GOT_BITS(statePtr->flags, TCP_NONBLOCKING)) {
        timeout = 0;
    } else {
        timeout = -1;
    }
    do {
        if (TclUnixWaitForFile(statePtr->fds.fd,
                TCL_WRITABLE | TCL_EXCEPTION, timeout) != 0) {
            TcpConnect(NULL, statePtr);
        }

        /*
         * Do this only once in the nonblocking case and repeat it until the
         * socket is final when blocking.
         */
    } while (timeout == -1 && GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT));

    if (errorCodePtr != NULL) {
        if (GOT_BITS(statePtr->flags, TCP_ASYNC_PENDING)) {
            *errorCodePtr = EAGAIN;
            return -1;
        } else if (statePtr->connectError != 0) {
            *errorCodePtr = ENOTCONN;
            return -1;
        }
    }
    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * TcpInputProc --
 *
 *	This function is invoked by the generic IO level to read input from a
 *	TCP socket based channel.
 *
 *	NOTE: We cannot share code with FilePipeInputProc because here we must
 *	use recv to obtain the input from the channel, not read.
 *
 * Results:
 *	The number of bytes read is returned or -1 on error. An output
 *	argument contains the POSIX error code on error, or zero if no error
 *	occurred.
 *
 * Side effects:
 *	Reads input from the input device of the channel.
 *
 *----------------------------------------------------------------------
 */

static int
TcpInputProc(
    void *instanceData,	/* Socket state. */
    char *buf,			/* Where to store data read. */
    int bufSize,		/* How much space is available in the
				 * buffer? */
    int *errorCodePtr)		/* Where to store error code. */
{
    TcpState *statePtr = (TcpState *)instanceData;
    int bytesRead;

    *errorCodePtr = 0;
    if (WaitForConnect(statePtr, errorCodePtr) != 0) {
	return -1;
    }
    bytesRead = recv(statePtr->fds.fd, buf, bufSize, 0);
    if (bytesRead >= 0) {
	return bytesRead;
    }
    if (errno == ECONNRESET) {
	/*
	 * Turn ECONNRESET into a soft EOF condition.
	 */

	return 0;
    }
    *errorCodePtr = errno;
    return -1;
}

/*
 *----------------------------------------------------------------------
 *
 * TcpOutputProc --
 *
 *	This function is invoked by the generic IO level to write output to a
 *	TCP socket based channel.
 *
 *	NOTE: We cannot share code with FilePipeOutputProc because here we
 *	must use send, not write, to get reliable error reporting.
 *
 * Results:
 *	The number of bytes written is returned. An output argument is set to
 *	a POSIX error code if an error occurred, or zero.
 *
 * Side effects:
 *	Writes output on the output device of the channel.
 *
 *----------------------------------------------------------------------
 */

static int
TcpOutputProc(
    void *instanceData,	/* Socket state. */
    const char *buf,		/* The data buffer. */
    int toWrite,		/* How many bytes to write? */
    int *errorCodePtr)		/* Where to store error code. */
{
    TcpState *statePtr = (TcpState *)instanceData;
    int written;

    *errorCodePtr = 0;
    if (WaitForConnect(statePtr, errorCodePtr) != 0) {
	return -1;
    }
    written = send(statePtr->fds.fd, buf, toWrite, 0);

    if (written >= 0) {
	return written;
    }
    *errorCodePtr = errno;
    return -1;
}

/*
 *----------------------------------------------------------------------
 *
 * TcpCloseProc --
 *
 *	This function is invoked by the generic IO level to perform
 *	channel-type-specific cleanup when a TCP socket based channel is
 *	closed.
 *
 * Results:
 *	0 if successful, the value of errno if failed.
 *
 * Side effects:
 *	Closes the socket of the channel.
 *
 *----------------------------------------------------------------------
 */

static int
TcpCloseProc(
    void *instanceData,	/* The socket to close. */
    TCL_UNUSED(Tcl_Interp *))
{
    TcpState *statePtr = (TcpState *)instanceData;
    int errorCode = 0;
    TcpFdList *fds;

    /*
     * Delete a file handler that may be active for this socket if this is a
     * server socket - the file handler was created automatically by Tcl as
     * part of the mechanism to accept new client connections. Channel
     * handlers are already deleted in the generic IO channel closing code
     * that called this function, so we do not have to delete them here.
     */

    for (fds = &statePtr->fds; fds != NULL; fds = fds->next) {
	if (fds->fd < 0) {
	    continue;
	}
	Tcl_DeleteFileHandler(fds->fd);
	if (close(fds->fd) < 0) {
	    errorCode = errno;
	}

    }
    fds = statePtr->fds.next;
    while (fds != NULL) {
	TcpFdList *next = fds->next;

	Tcl_Free(fds);
	fds = next;
    }
    if (statePtr->addrlist != NULL) {
        freeaddrinfo(statePtr->addrlist);
    }
    if (statePtr->myaddrlist != NULL) {
        freeaddrinfo(statePtr->myaddrlist);
    }
    Tcl_Free(statePtr);
    return errorCode;
}

/*
 *----------------------------------------------------------------------
 *
 * TcpClose2Proc --
 *
 *	This function is called by the generic IO level to perform the channel
 *	type specific part of a half-close: namely, a shutdown() on a socket.
 *
 * Results:
 *	0 if successful, the value of errno if failed.
 *
 * Side effects:
 *	Shuts down one side of the socket.
 *
 *----------------------------------------------------------------------
 */

static int
TcpClose2Proc(
    void *instanceData,	/* The socket to close. */
    TCL_UNUSED(Tcl_Interp *),
    int flags)			/* Flags that indicate which side to close. */
{
    TcpState *statePtr = (TcpState *)instanceData;
    int readError = 0;
    int writeError = 0;

    /*
     * Shutdown the OS socket handle.
     */
    if ((flags & (TCL_CLOSE_READ|TCL_CLOSE_WRITE)) == 0) {
	return TcpCloseProc(instanceData, NULL);
    }
    if ((flags & TCL_CLOSE_READ) && (shutdown(statePtr->fds.fd, SHUT_RD) < 0)) {
	readError = errno;
    }
    if ((flags & TCL_CLOSE_WRITE) && (shutdown(statePtr->fds.fd, SHUT_WR) < 0)) {
	writeError = errno;
    }
    return (readError != 0) ? readError : writeError;
}

/*
 *----------------------------------------------------------------------
 *
 * TcpHostPortList --
 *
 *	This function is called by the -gethostname and -getpeername switches
 *	of TcpGetOptionProc() to add three list elements with the textual
 *	representation of the given address to the given DString.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Adds three elements do dsPtr
 *
 *----------------------------------------------------------------------
 */

#ifndef NEED_FAKE_RFC2553
#if defined (__clang__) || ((__GNUC__)  && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 5))))
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wstrict-aliasing"
#endif
static inline int
IPv6AddressNeedsNumericRendering(
    struct in6_addr addr)
{
    if (IN6_ARE_ADDR_EQUAL(&addr, &in6addr_any)) {
        return 1;
    }

    /*
     * The IN6_IS_ADDR_V4MAPPED macro has a problem with aliasing warnings on
     * at least some versions of OSX.
     */

    if (!IN6_IS_ADDR_V4MAPPED(&addr)) {
        return 0;
    }

    return (addr.s6_addr[12] == 0 && addr.s6_addr[13] == 0
            && addr.s6_addr[14] == 0 && addr.s6_addr[15] == 0);
}
#if defined (__clang__) || ((__GNUC__)  && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 5))))
#pragma GCC diagnostic pop
#endif
#endif /* NEED_FAKE_RFC2553 */

static void
TcpHostPortList(
    Tcl_Interp *interp,
    Tcl_DString *dsPtr,
    address addr,
    socklen_t salen)
{
#define SUPPRESS_RDNS_VAR "::tcl::unsupported::noReverseDNS"
    char host[NI_MAXHOST], nhost[NI_MAXHOST], nport[NI_MAXSERV];
    int flags = 0;

    getnameinfo(&addr.sa, salen, nhost, sizeof(nhost), nport, sizeof(nport),
            NI_NUMERICHOST | NI_NUMERICSERV);
    Tcl_DStringAppendElement(dsPtr, nhost);

    /*
     * We don't want to resolve INADDR_ANY and sin6addr_any; they can
     * sometimes cause problems (and never have a name).
     */

    if (addr.sa.sa_family == AF_INET) {
        if (addr.sa4.sin_addr.s_addr == INADDR_ANY) {
            flags |= NI_NUMERICHOST;
        }
#ifndef NEED_FAKE_RFC2553
    } else if (addr.sa.sa_family == AF_INET6) {
        if (IPv6AddressNeedsNumericRendering(addr.sa6.sin6_addr)) {
            flags |= NI_NUMERICHOST;
        }
#endif /* NEED_FAKE_RFC2553 */
    }

    /*
     * Check if reverse DNS has been switched off globally.
     */

    if (interp != NULL &&
            Tcl_GetVar2(interp, SUPPRESS_RDNS_VAR, NULL, 0) != NULL) {
        flags |= NI_NUMERICHOST;
    }
    if (getnameinfo(&addr.sa, salen, host, sizeof(host), NULL, 0,
            flags) == 0) {
        /*
         * Reverse mapping worked.
         */

        Tcl_DStringAppendElement(dsPtr, host);
    } else {
        /*
         * Reverse mapping failed - use the numeric rep once more.
         */

        Tcl_DStringAppendElement(dsPtr, nhost);
    }
    Tcl_DStringAppendElement(dsPtr, nport);
}

/*
 *----------------------------------------------------------------------
 *
 * TcpSetOptionProc --
 *
 *	Sets TCP channel specific options.
 *
 * Results:
 *	None, unless an error happens.
 *
 * Side effects:
 *	Changes attributes of the socket at the system level.
 *
 *----------------------------------------------------------------------
 */

static int
TcpSetOptionProc(
    void *instanceData,		/* Socket state. */
    Tcl_Interp *interp,		/* For error reporting - can be NULL. */
    const char *optionName,	/* Name of the option to set. */
    const char *value)		/* New value for option. */
{
    TcpState *statePtr = (TcpState *)instanceData;
    size_t len = 0;

    if (optionName != NULL) {
	len = strlen(optionName);
    }

    if ((len > 1) && (optionName[1] == 'k') &&
	    (strncmp(optionName, "-keepalive", len) == 0)) {
	int val = 0, ret;

	if (Tcl_GetBoolean(interp, value, &val) != TCL_OK) {
	    return TCL_ERROR;
	}
#if defined(SO_KEEPALIVE)
	ret = setsockopt(statePtr->fds.fd, SOL_SOCKET, SO_KEEPALIVE,
		(const char *) &val, sizeof(int));
#else
	ret = -1;
	Tcl_SetErrno(ENOTSUP);
#endif
	if (ret < 0) {
	    if (interp) {
		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
			"couldn't set socket option: %s",
			Tcl_PosixError(interp)));
	    }
	    return TCL_ERROR;
	}
	return TCL_OK;
    }
    if ((len > 1) && (optionName[1] == 'n') &&
	    (strncmp(optionName, "-nodelay", len) == 0)) {
	int val = 0, ret;

	if (Tcl_GetBoolean(interp, value, &val) != TCL_OK) {
	    return TCL_ERROR;
	}
#if defined(SOL_TCP) && defined(TCP_NODELAY)
	ret = setsockopt(statePtr->fds.fd, SOL_TCP, TCP_NODELAY,
		(const char *) &val, sizeof(int));
#else
	ret = -1;
	Tcl_SetErrno(ENOTSUP);
#endif
	if (ret < 0) {
	    if (interp) {
		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
			"couldn't set socket option: %s",
			Tcl_PosixError(interp)));
	    }
	    return TCL_ERROR;
	}
	return TCL_OK;
    }
    return Tcl_BadChannelOption(interp, optionName, "keepalive nodelay");
}

/*
 *----------------------------------------------------------------------
 *
 * TcpGetOptionProc --
 *
 *	Computes an option value for a TCP socket based channel, or a list of
 *	all options and their values.
 *
 *	Note: This code is based on code contributed by John Haxby.
 *
 * Results:
 *	A standard Tcl result. The value of the specified option or a list of
 *	all options and their values is returned in the supplied DString. Sets
 *	Error message if needed.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
TcpGetOptionProc(
    void *instanceData,		/* Socket state. */
    Tcl_Interp *interp,		/* For error reporting - can be NULL. */
    const char *optionName,	/* Name of the option to retrieve the value
				 * for, or NULL to get all options and their
				 * values. */
    Tcl_DString *dsPtr)		/* Where to store the computed value;
				 * initialized by caller. */
{
    TcpState *statePtr = (TcpState *)instanceData;
    size_t len = 0;

    if (optionName != NULL) {
	len = strlen(optionName);
    }

    if ((len > 1) && (optionName[1] == 'e') &&
	    (strncmp(optionName, "-error", len) == 0)) {
	socklen_t optlen = sizeof(int);

	WaitForConnect(statePtr, NULL);
        if (GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT)) {
            /*
             * Suppress errors as long as we are not done.
             */

            errno = 0;
        } else if (statePtr->connectError != 0) {
            errno = statePtr->connectError;
            statePtr->connectError = 0;
        } else {
            int err;

            getsockopt(statePtr->fds.fd, SOL_SOCKET, SO_ERROR, (char *) &err,
                    &optlen);
            errno = err;
        }
        if (errno != 0) {
	    Tcl_DStringAppend(dsPtr, Tcl_ErrnoMsg(errno), TCL_INDEX_NONE);
        }
	return TCL_OK;
    }

    if ((len > 1) && (optionName[1] == 'c') &&
	    (strncmp(optionName, "-connecting", len) == 0)) {
	WaitForConnect(statePtr, NULL);
	Tcl_DStringAppend(dsPtr,
		GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT) ? "1" : "0", TCL_INDEX_NONE);
        return TCL_OK;
    }

    if ((len == 0) || ((len > 1) && (optionName[1] == 'p') &&
	    (strncmp(optionName, "-peername", len) == 0))) {
        address peername;
        socklen_t size = sizeof(peername);

	WaitForConnect(statePtr, NULL);
	if (GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT)) {
	    /*
	     * In async connect output an empty string
	     */

	    if (len == 0) {
		Tcl_DStringAppendElement(dsPtr, "-peername");
		Tcl_DStringAppendElement(dsPtr, "");
	    } else {
		return TCL_OK;
	    }
	} else if (getpeername(statePtr->fds.fd, &peername.sa, &size) >= 0) {
	    /*
	     * Peername fetch succeeded - output list
	     */

	    if (len == 0) {
		Tcl_DStringAppendElement(dsPtr, "-peername");
		Tcl_DStringStartSublist(dsPtr);
	    }
            TcpHostPortList(interp, dsPtr, peername, size);
	    if (len) {
                return TCL_OK;
            }
            Tcl_DStringEndSublist(dsPtr);
	} else {
	    /*
	     * getpeername failed - but if we were asked for all the options
	     * (len==0), don't flag an error at that point because it could be
	     * an fconfigure request on a server socket (which have no peer).
	     * Same must be done on win&mac.
	     */

	    if (len) {
		if (interp) {
		    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                            "can't get peername: %s",
			    Tcl_PosixError(interp)));
		}
		return TCL_ERROR;
	    }
	}
    }

    if ((len == 0) || ((len > 1) && (optionName[1] == 's') &&
	    (strncmp(optionName, "-sockname", len) == 0))) {
	TcpFdList *fds;
	address sockname;
	socklen_t size;
	int found = 0;

	WaitForConnect(statePtr, NULL);
	if (len == 0) {
	    Tcl_DStringAppendElement(dsPtr, "-sockname");
	    Tcl_DStringStartSublist(dsPtr);
	}
	if (GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT)) {
	    /*
	     * In async connect output an empty string
	     */

            found = 1;
	} else {
	    for (fds = &statePtr->fds; fds != NULL; fds = fds->next) {
		size = sizeof(sockname);
		if (getsockname(fds->fd, &(sockname.sa), &size) >= 0) {
		    found = 1;
		    TcpHostPortList(interp, dsPtr, sockname, size);
		}
	    }
	}
        if (found) {
            if (len) {
                return TCL_OK;
            }
            Tcl_DStringEndSublist(dsPtr);
        } else {
            if (interp) {
                Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                        "can't get sockname: %s", Tcl_PosixError(interp)));
            }
	    return TCL_ERROR;
	}
    }

    if ((len == 0) || ((len > 1) && (optionName[1] == 'k') &&
	    (strncmp(optionName, "-keepalive", len) == 0))) {
	int opt = 0;
#if defined(SO_KEEPALIVE)
	socklen_t size = sizeof(opt);
#endif

	if (len == 0) {
	    Tcl_DStringAppendElement(dsPtr, "-keepalive");
	}
#if defined(SO_KEEPALIVE)
	getsockopt(statePtr->fds.fd, SOL_SOCKET, SO_KEEPALIVE,
		(char *) &opt, &size);
#endif
	Tcl_DStringAppendElement(dsPtr, opt ? "1" : "0");
	if (len > 0) {
	    return TCL_OK;
	}
    }

    if ((len == 0) || ((len > 1) && (optionName[1] == 'n') &&
	    (strncmp(optionName, "-nodelay", len) == 0))) {
	int opt = 0;
#if defined(SOL_TCP) && defined(TCP_NODELAY)
	socklen_t size = sizeof(opt);
#endif

	if (len == 0) {
	    Tcl_DStringAppendElement(dsPtr, "-nodelay");
	}
#if defined(SOL_TCP) && defined(TCP_NODELAY)
	getsockopt(statePtr->fds.fd, SOL_TCP, TCP_NODELAY,
		(char *) &opt, &size);
#endif
	Tcl_DStringAppendElement(dsPtr, opt ? "1" : "0");
	if (len > 0) {
	    return TCL_OK;
	}
    }

    if (len > 0) {
	return Tcl_BadChannelOption(interp, optionName,
                "connecting keepalive nodelay peername sockname");
    }

    return TCL_OK;
}

/*
 * ----------------------------------------------------------------------
 *
 * TcpThreadActionProc --
 *
 *	Handles detach/attach for asynchronously connecting socket.
 *
 *	Reassigning the file handler associated with thread-related channel
 *	notification, responsible for callbacks (signaling that asynchronous
 *	connection attempt has succeeded or failed).
 *
 * Results:
 *	None.
 *
 * ----------------------------------------------------------------------
 */

static void
TcpThreadActionProc(
    void *instanceData,
    int action)
{
    TcpState *statePtr = (TcpState *)instanceData;

    if (GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT)) {
	/*
	 * Async-connecting socket must get reassigned handler if it have been
	 * transferred to another thread. Remove the handler if the socket is
	 * not managed by this thread anymore and create new handler (TSD related)
	 * so the callback will run in the correct thread, bug [f583715154].
	 */
	switch (action) {
	  case TCL_CHANNEL_THREAD_REMOVE:
	    CLEAR_BITS(statePtr->flags, TCP_ASYNC_PENDING);
	    Tcl_DeleteFileHandler(statePtr->fds.fd);
	  break;
	  case TCL_CHANNEL_THREAD_INSERT:
	    Tcl_CreateFileHandler(statePtr->fds.fd,
		TCL_WRITABLE | TCL_EXCEPTION, TcpAsyncCallback, statePtr);
	    SET_BITS(statePtr->flags, TCP_ASYNC_PENDING);
	  break;
	}
    }
}

/*
 * ----------------------------------------------------------------------
 *
 * TcpWatchProc --
 *
 *	Initialize the notifier to watch the fd from this channel.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Sets up the notifier so that a future event on the channel will be
 *	seen by Tcl.
 *
 * ----------------------------------------------------------------------
 */

static void
WrapNotify(
    void *clientData,
    int mask)
{
    TcpState *statePtr = (TcpState *) clientData;
    int newmask = mask & statePtr->interest;

    if (newmask == 0) {
	/*
	 * There was no overlap between the states the channel is interested
	 * in notifications for, and the states that are reported present on
	 * the file descriptor by select().  The only way that can happen is
	 * when the channel is interested in a writable condition, and only a
	 * readable state is reported present (see TcpWatchProc() below).  In
	 * that case, signal back to the caller the writable state, which is
	 * really an error condition.  As an extra check on that assumption,
	 * check for a non-zero value of errno before reporting an artificial
	 * writable state.
	 */

	if (errno == 0) {
	    return;
	}
	newmask = TCL_WRITABLE;
    }
    Tcl_NotifyChannel(statePtr->channel, newmask);
}

static void
TcpWatchProc(
    void *instanceData,	/* The socket state. */
    int mask)			/* Events of interest; an OR-ed combination of
				 * TCL_READABLE, TCL_WRITABLE and
				 * TCL_EXCEPTION. */
{
    TcpState *statePtr = (TcpState *)instanceData;

    if (statePtr->acceptProc != NULL) {
        /*
         * Make sure we don't mess with server sockets since they will never
         * be readable or writable at the Tcl level. This keeps Tcl scripts
         * from interfering with the -accept behavior (bug #3394732).
         */

    	return;
    }

    if (GOT_BITS(statePtr->flags, TCP_ASYNC_PENDING)) {
        /*
         * Async sockets use a FileHandler internally while connecting, so we
         * need to cache this request until the connection has succeeded.
         */

        statePtr->filehandlers = mask;
    } else if (mask) {

	/*
	 * Whether it is a bug or feature or otherwise, it is a fact of life
	 * that on at least some Linux kernels select() fails to report that a
	 * socket file descriptor is writable when the other end of the socket
	 * is closed.  This is in contrast to the guarantees Tcl makes that
	 * its channels become writable and fire writable events on an error
	 * condition.  This has caused a leak of file descriptors in a state of
	 * background flushing.  See Tcl ticket 1758a0b603.
	 *
	 * As a workaround, when our caller indicates an interest in writable
	 * notifications, we must tell the notifier built around select() that
	 * we are interested in the readable state of the file descriptor as
	 * well, as that is the only reliable means to get notified of error
	 * conditions.  Then it is the task of WrapNotify() above to untangle
	 * the meaning of these channel states and report the chan events as
	 * best it can.  We save a copy of the mask passed in to assist with
	 * that.
	 */

	statePtr->interest = mask;
	Tcl_CreateFileHandler(statePtr->fds.fd, mask|TCL_READABLE,
		WrapNotify, statePtr);
    } else {
	Tcl_DeleteFileHandler(statePtr->fds.fd);
    }
}

/*
 * ----------------------------------------------------------------------
 *
 * TcpGetHandleProc --
 *
 *	Called from Tcl_GetChannelHandle to retrieve OS handles from inside a
 *	TCP socket based channel.
 *
 * Results:
 *	Returns TCL_OK with the fd in handlePtr, or TCL_ERROR if there is no
 *	handle for the specified direction.
 *
 * Side effects:
 *	None.
 *
 * ----------------------------------------------------------------------
 */

static int
TcpGetHandleProc(
    void *instanceData,	/* The socket state. */
    TCL_UNUSED(int) /*direction*/,
    void **handlePtr)	/* Where to store the handle. */
{
    TcpState *statePtr = (TcpState *)instanceData;

    *handlePtr = INT2PTR(statePtr->fds.fd);
    return TCL_OK;
}

/*
 * ----------------------------------------------------------------------
 *
 * TcpAsyncCallback --
 *
 *	Called by the event handler that TcpConnect sets up internally for
 *	[socket -async] to get notified when the asynchronous connection
 *	attempt has succeeded or failed.
 *
 * ----------------------------------------------------------------------
 */

static void
TcpAsyncCallback(
    void *clientData,	/* The socket state. */
    TCL_UNUSED(int) /*mask*/)
{
    TcpConnect(NULL, (TcpState *)clientData);
}

/*
 * ----------------------------------------------------------------------
 *
 * TcpConnect --
 *
 *	This function opens a new socket in client mode.
 *
 * Results:
 *      TCL_OK, if the socket was successfully connected or an asynchronous
 *      connection is in progress. If an error occurs, TCL_ERROR is returned
 *      and an error message is left in interp.
 *
 * Side effects:
 *	Opens a socket.
 *
 * Remarks:
 *	A single host name may resolve to more than one IP address, e.g. for
 *	an IPv4/IPv6 dual stack host. For handling asynchronously connecting
 *	sockets in the background for such hosts, this function can act as a
 *	coroutine. On the first call, it sets up the control variables for the
 *	two nested loops over the local and remote addresses. Once the first
 *	connection attempt is in progress, it sets up itself as a writable
 *	event handler for that socket, and returns. When the callback occurs,
 *	control is transferred to the "reenter" label, right after the initial
 *	return and the loops resume as if they had never been interrupted.
 *	For synchronously connecting sockets, the loops work the usual way.
 *
 * ----------------------------------------------------------------------
 */

static int
TcpConnect(
    Tcl_Interp *interp,		/* For error reporting; can be NULL. */
    TcpState *statePtr)
{
    socklen_t optlen;
    int async_callback = GOT_BITS(statePtr->flags, TCP_ASYNC_PENDING);
    int ret = -1, error = EHOSTUNREACH;
    int async = GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT);
    static const int reuseaddr = 1;

    if (async_callback) {
        goto reenter;
    }

    for (statePtr->addr = statePtr->addrlist; statePtr->addr != NULL;
            statePtr->addr = statePtr->addr->ai_next) {
        for (statePtr->myaddr = statePtr->myaddrlist;
                statePtr->myaddr != NULL;
                statePtr->myaddr = statePtr->myaddr->ai_next) {
	    /*
	     * No need to try combinations of local and remote addresses of
	     * different families.
	     */

	    if (statePtr->myaddr->ai_family != statePtr->addr->ai_family) {
		continue;
	    }

            /*
             * Close the socket if it is still open from the last unsuccessful
             * iteration.
             */

            if (statePtr->fds.fd >= 0) {
		close(statePtr->fds.fd);
		statePtr->fds.fd = -1;
                errno = 0;
	    }

	    statePtr->fds.fd = socket(statePtr->addr->ai_family, SOCK_STREAM,
                    0);
	    if (statePtr->fds.fd < 0) {
		continue;
	    }

	    /*
	     * Set the close-on-exec flag so that the socket will not get
	     * inherited by child processes.
	     */

	    fcntl(statePtr->fds.fd, F_SETFD, FD_CLOEXEC);

	    /*
	     * Set kernel space buffering
	     */

	    TclSockMinimumBuffers(INT2PTR(statePtr->fds.fd), SOCKET_BUFSIZE);

	    if (async) {
                ret = TclUnixSetBlockingMode(statePtr->fds.fd,
                        TCL_MODE_NONBLOCKING);
                if (ret < 0) {
                    continue;
                }
            }

            /*
             * Must reset the error variable here, before we use it for the
             * first time in this iteration.
             */

            error = 0;

            (void) setsockopt(statePtr->fds.fd, SOL_SOCKET, SO_REUSEADDR,
                    (char *) &reuseaddr, sizeof(reuseaddr));
            ret = bind(statePtr->fds.fd, statePtr->myaddr->ai_addr,
                    statePtr->myaddr->ai_addrlen);
            if (ret < 0) {
                error = errno;
                continue;
            }

	    /*
	     * Attempt to connect. The connect may fail at present with an
	     * EINPROGRESS but at a later time it will complete. The caller
	     * will set up a file handler on the socket if she is interested
	     * in being informed when the connect completes.
	     */

	    ret = connect(statePtr->fds.fd, statePtr->addr->ai_addr,
                        statePtr->addr->ai_addrlen);
            if (ret < 0) {
                error = errno;
            }
	    if (ret < 0 && errno == EINPROGRESS) {
                Tcl_CreateFileHandler(statePtr->fds.fd,
                        TCL_WRITABLE | TCL_EXCEPTION, TcpAsyncCallback,
                        statePtr);
                errno = EWOULDBLOCK;
                SET_BITS(statePtr->flags, TCP_ASYNC_PENDING);
                return TCL_OK;

            reenter:
                CLEAR_BITS(statePtr->flags, TCP_ASYNC_PENDING);
                Tcl_DeleteFileHandler(statePtr->fds.fd);

                /*
                 * Read the error state from the socket to see if the async
                 * connection has succeeded or failed. As this clears the
                 * error condition, we cache the status in the socket state
                 * struct for later retrieval by [fconfigure -error].
                 */

                optlen = sizeof(int);

                getsockopt(statePtr->fds.fd, SOL_SOCKET, SO_ERROR,
                        (char *) &error, &optlen);
                errno = error;
            }
	    if (error == 0) {
		goto out;
	    }
	}
    }

  out:
    statePtr->connectError = error;
    CLEAR_BITS(statePtr->flags, TCP_ASYNC_CONNECT);
    if (async_callback) {
        /*
         * An asynchonous connection has finally succeeded or failed.
         */

        TcpWatchProc(statePtr, statePtr->filehandlers);
        TclUnixSetBlockingMode(statePtr->fds.fd, statePtr->cachedBlocking);

        if (error != 0) {
            SET_BITS(statePtr->flags, TCP_ASYNC_FAILED);
        }

        /*
         * We need to forward the writable event that brought us here, because
         * upon reading of getsockopt(SO_ERROR), at least some OSes clear the
         * writable state from the socket, and so a subsequent select() on
         * behalf of a script level [fileevent] would not fire. It doesn't
         * hurt that this is also called in the successful case and will save
         * the event mechanism one roundtrip through select().
         */

	if (statePtr->cachedBlocking == TCL_MODE_NONBLOCKING) {
	    Tcl_NotifyChannel(statePtr->channel, TCL_WRITABLE);
	}
    }
    if (error != 0) {
        /*
         * Failure for either a synchronous connection, or an async one that
         * failed before it could enter background mode, e.g. because an
         * invalid -myaddr was given.
         */

        if (interp != NULL) {
            errno = error;
            Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                    "couldn't open socket: %s", Tcl_PosixError(interp)));
        }
        return TCL_ERROR;
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_OpenTcpClient --
 *
 *	Opens a TCP client socket and creates a channel around it.
 *
 * Results:
 *	The channel or NULL if failed. An error message is returned in the
 *	interpreter on failure.
 *
 * Side effects:
 *	Opens a client socket and creates a new channel.
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
Tcl_OpenTcpClient(
    Tcl_Interp *interp,		/* For error reporting; can be NULL. */
    int port,			/* Port number to open. */
    const char *host,		/* Host on which to open port. */
    const char *myaddr,		/* Client-side address */
    int myport,			/* Client-side port */
    int async)			/* If nonzero, attempt to do an asynchronous
				 * connect. Otherwise we do a blocking
				 * connect. */
{
    TcpState *statePtr;
    const char *errorMsg = NULL;
    struct addrinfo *addrlist = NULL, *myaddrlist = NULL;
    char channelName[SOCK_CHAN_LENGTH];

    /*
     * Do the name lookups for the local and remote addresses.
     */

    if (!TclCreateSocketAddress(interp, &addrlist, host, port, 0, &errorMsg)
            || !TclCreateSocketAddress(interp, &myaddrlist, myaddr, myport, 1,
                    &errorMsg)) {
        if (addrlist != NULL) {
            freeaddrinfo(addrlist);
        }
        if (interp != NULL) {
            Tcl_SetObjResult(interp, Tcl_ObjPrintf(
                    "couldn't open socket: %s", errorMsg));
        }
        return NULL;
    }

    /*
     * Allocate a new TcpState for this socket.
     */

    statePtr = (TcpState *)Tcl_Alloc(sizeof(TcpState));
    memset(statePtr, 0, sizeof(TcpState));
    statePtr->flags = async ? TCP_ASYNC_CONNECT : 0;
    statePtr->cachedBlocking = TCL_MODE_BLOCKING;
    statePtr->addrlist = addrlist;
    statePtr->myaddrlist = myaddrlist;
    statePtr->fds.fd = -1;

    /*
     * Create a new client socket and wrap it in a channel.
     */

    if (TcpConnect(interp, statePtr) != TCL_OK) {
        TcpCloseProc(statePtr, NULL);
        return NULL;
    }

    snprintf(channelName, sizeof(channelName), SOCK_TEMPLATE, PTR2INT(statePtr));

    statePtr->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
            statePtr, TCL_READABLE | TCL_WRITABLE);
    if (Tcl_SetChannelOption(interp, statePtr->channel, "-translation",
	    "auto crlf") == TCL_ERROR) {
	Tcl_CloseEx(NULL, statePtr->channel, 0);
	return NULL;
    }
    return statePtr->channel;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_MakeTcpClientChannel --
 *
 *	Creates a Tcl_Channel from an existing client TCP socket.
 *
 * Results:
 *	The Tcl_Channel wrapped around the preexisting TCP socket.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
Tcl_MakeTcpClientChannel(
    void *sock)		/* The socket to wrap up into a channel. */
{
    return (Tcl_Channel) TclpMakeTcpClientChannelMode(sock,
            TCL_READABLE | TCL_WRITABLE);
}

/*
 *----------------------------------------------------------------------
 *
 * TclpMakeTcpClientChannelMode --
 *
 *	Creates a Tcl_Channel from an existing client TCP socket
 *	with given mode.
 *
 * Results:
 *	The Tcl_Channel wrapped around the preexisting TCP socket.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

void *
TclpMakeTcpClientChannelMode(
    void *sock,		/* The socket to wrap up into a channel. */
    int mode)			/* OR'ed combination of TCL_READABLE and
				 * TCL_WRITABLE to indicate file mode. */
{
    TcpState *statePtr;
    char channelName[SOCK_CHAN_LENGTH];

    statePtr = (TcpState *)Tcl_Alloc(sizeof(TcpState));
    memset(statePtr, 0, sizeof(TcpState));
    statePtr->fds.fd = PTR2INT(sock);
    statePtr->flags = 0;

    snprintf(channelName, sizeof(channelName), SOCK_TEMPLATE, PTR2INT(statePtr));

    statePtr->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
	    statePtr, mode);
    if (Tcl_SetChannelOption(NULL, statePtr->channel, "-translation",
	    "auto crlf") == TCL_ERROR) {
	Tcl_CloseEx(NULL, statePtr->channel, 0);
	return NULL;
    }
    return statePtr->channel;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_OpenTcpServerEx --
 *
 *	Opens a TCP server socket and creates a channel around it.
 *
 * Results:
 *	The channel or NULL if failed. If an error occurred, an error message
 *	is left in the interp's result if interp is not NULL.
 *
 * Side effects:
 *	Opens a server socket and creates a new channel.
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
Tcl_OpenTcpServerEx(
    Tcl_Interp *interp,		/* For error reporting - may be NULL. */
    const char *service,	/* Port number to open. */
    const char *myHost,		/* Name of local host. */
    unsigned int flags,		/* Flags. */
    int backlog,                /* Length of OS listen backlog queue. */
    Tcl_TcpAcceptProc *acceptProc,
				/* Callback for accepting connections from new
				 * clients. */
    void *acceptProcData)	/* Data for the callback. */
{
    int status = 0, sock = -1, optvalue, port, chosenport;
    struct addrinfo *addrlist = NULL, *addrPtr;	/* socket address */
    TcpState *statePtr = NULL;
    char channelName[SOCK_CHAN_LENGTH];
    const char *errorMsg = NULL;
    TcpFdList *fds = NULL, *newfds;

    /*
     * Try to record and return the most meaningful error message, i.e. the
     * one from the first socket that went the farthest before it failed.
     */

    enum { LOOKUP, SOCKET, BIND, LISTEN } howfar = LOOKUP;
    int my_errno = 0;

    /*
     * If we were called with port 0 to listen on a random port number, we
     * copy the port number from the first member of the addrinfo list to all
     * subsequent members, so that IPv4 and IPv6 listen on the same port. This
     * might fail to bind() with EADDRINUSE if a port is free on the first
     * address family in the list but already used on the other. In this case
     * we revert everything we've done so far and start from scratch hoping
     * that next time we'll find a port number that is usable on all address
     * families. We try this at most MAXRETRY times to avoid an endless loop
     * if all ports are taken.
     */

    int retry = 0;
#define MAXRETRY 10

 repeat:
    if (retry > 0) {
        if (statePtr != NULL) {
            TcpCloseProc(statePtr, NULL);
            statePtr = NULL;
        }
        if (addrlist != NULL) {
            freeaddrinfo(addrlist);
            addrlist = NULL;
        }
        if (retry >= MAXRETRY) {
            goto error;
        }
    }
    retry++;
    chosenport = 0;

    if (TclSockGetPort(interp, service, "tcp", &port) != TCL_OK) {
	errorMsg = "invalid port number";
	goto error;
    }

    if (!TclCreateSocketAddress(interp, &addrlist, myHost, port, 1,
            &errorMsg)) {
	my_errno = errno;
	goto error;
    }

    for (addrPtr = addrlist; addrPtr != NULL; addrPtr = addrPtr->ai_next) {
	sock = socket(addrPtr->ai_family, addrPtr->ai_socktype,
                addrPtr->ai_protocol);
	if (sock == -1) {
	    if (howfar < SOCKET) {
		howfar = SOCKET;
		my_errno = errno;
	    }
	    continue;
	}

	/*
	 * Set the close-on-exec flag so that the socket will not get
	 * inherited by child processes.
	 */

	fcntl(sock, F_SETFD, FD_CLOEXEC);

	/*
	 * Set kernel space buffering
	 */

	TclSockMinimumBuffers(INT2PTR(sock), SOCKET_BUFSIZE);

	/*
	 * Set up to reuse server addresses and/or ports if requested.
	 */

	if (GOT_BITS(flags, TCL_TCPSERVER_REUSEADDR)) {
	    optvalue = 1;
	    (void) setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
		    (char *) &optvalue, sizeof(optvalue));
	}

	if (GOT_BITS(flags, TCL_TCPSERVER_REUSEPORT)) {
#ifndef SO_REUSEPORT
	    /*
	     * If the platform doesn't support the SO_REUSEPORT flag we can't
	     * do much beside erroring out.
	     */

	    errorMsg = "SO_REUSEPORT isn't supported by this platform";
	    goto error;
#else
	    optvalue = 1;
	    (void) setsockopt(sock, SOL_SOCKET, SO_REUSEPORT,
		    (char *) &optvalue, sizeof(optvalue));
#endif
	}

        /*
         * Make sure we use the same port number when opening two server
         * sockets for IPv4 and IPv6 on a random port.
         *
         * As sockaddr_in6 uses the same offset and size for the port member
         * as sockaddr_in, we can handle both through the IPv4 API.
         */

	if (port == 0 && chosenport != 0) {
	    ((struct sockaddr_in *) addrPtr->ai_addr)->sin_port =
                    htons(chosenport);
	}

#ifdef IPV6_V6ONLY
	/*
         * Missing on: Solaris 2.8
         */

        if (addrPtr->ai_family == AF_INET6) {
            int v6only = 1;

            (void) setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY,
                    &v6only, sizeof(v6only));
        }
#endif /* IPV6_V6ONLY */

	status = bind(sock, addrPtr->ai_addr, addrPtr->ai_addrlen);
        if (status == -1) {
	    if (howfar < BIND) {
		howfar = BIND;
		my_errno = errno;
	    }
            close(sock);
            sock = -1;
            if (port == 0 && errno == EADDRINUSE) {
                goto repeat;
            }
            continue;
        }
        if (port == 0 && chosenport == 0) {
            address sockname;
            socklen_t namelen = sizeof(sockname);

            /*
             * Synchronize port numbers when binding to port 0 of multiple
             * addresses.
             */

            if (getsockname(sock, &sockname.sa, &namelen) >= 0) {
                chosenport = ntohs(sockname.sa4.sin_port);
            }
        }
        if (backlog < 0) {
            backlog = SOMAXCONN;
        }
        status = listen(sock, backlog);
        if (status < 0) {
	    if (howfar < LISTEN) {
		howfar = LISTEN;
		my_errno = errno;
	    }
            close(sock);
            sock = -1;
            if (port == 0 && errno == EADDRINUSE) {
                goto repeat;
            }
            continue;
        }
        if (statePtr == NULL) {
            /*
             * Allocate a new TcpState for this socket.
             */

            statePtr = (TcpState *)Tcl_Alloc(sizeof(TcpState));
            memset(statePtr, 0, sizeof(TcpState));
            statePtr->acceptProc = acceptProc;
            statePtr->acceptProcData = acceptProcData;
            snprintf(channelName, sizeof(channelName), SOCK_TEMPLATE, PTR2INT(statePtr));
            newfds = &statePtr->fds;
        } else {
            newfds = (TcpFdList *)Tcl_Alloc(sizeof(TcpFdList));
            memset(newfds, (int) 0, sizeof(TcpFdList));
            fds->next = newfds;
        }
        newfds->fd = sock;
        newfds->statePtr = statePtr;
        fds = newfds;

        /*
         * Set up the callback mechanism for accepting connections from new
         * clients.
         */

        Tcl_CreateFileHandler(sock, TCL_READABLE, TcpAccept, fds);
    }

  error:
    if (addrlist != NULL) {
	freeaddrinfo(addrlist);
    }
    if (statePtr != NULL) {
	statePtr->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
		statePtr, 0);
	return statePtr->channel;
    }
    if (interp != NULL) {
        Tcl_Obj *errorObj = Tcl_NewStringObj("couldn't open socket: ", TCL_INDEX_NONE);

	if (errorMsg == NULL) {
            errno = my_errno;
            Tcl_AppendToObj(errorObj, Tcl_PosixError(interp), TCL_INDEX_NONE);
        } else {
	    Tcl_AppendToObj(errorObj, errorMsg, TCL_INDEX_NONE);
	}
        Tcl_SetObjResult(interp, errorObj);
    }
    if (sock != -1) {
	close(sock);
    }
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * TcpAccept --
 *	Accept a TCP socket connection.	 This is called by the event loop.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Creates a new connection socket. Calls the registered callback for the
 *	connection acceptance mechanism.
 *
 *----------------------------------------------------------------------
 */

static void
TcpAccept(
    void *data,		/* Callback token. */
    TCL_UNUSED(int) /*mask*/)
{
    TcpFdList *fds = (TcpFdList *)data;	/* Client data of server socket. */
    int newsock;		/* The new client socket */
    TcpState *newSockState;	/* State for new socket. */
    address addr;		/* The remote address */
    socklen_t len;		/* For accept interface */
    char channelName[SOCK_CHAN_LENGTH];
    char host[NI_MAXHOST], port[NI_MAXSERV];

    len = sizeof(addr);
    newsock = accept(fds->fd, &addr.sa, &len);
    if (newsock < 0) {
	return;
    }

    /*
     * Set close-on-exec flag to prevent the newly accepted socket from being
     * inherited by child processes.
     */

    (void) fcntl(newsock, F_SETFD, FD_CLOEXEC);

    newSockState = (TcpState *)Tcl_Alloc(sizeof(TcpState));
    memset(newSockState, 0, sizeof(TcpState));
    newSockState->flags = 0;
    newSockState->fds.fd = newsock;

    snprintf(channelName, sizeof(channelName), SOCK_TEMPLATE, PTR2INT(newSockState));
    newSockState->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
	    newSockState, TCL_READABLE | TCL_WRITABLE);

    Tcl_SetChannelOption(NULL, newSockState->channel, "-translation",
	    "auto crlf");

    if (fds->statePtr->acceptProc != NULL) {
	getnameinfo(&addr.sa, len, host, sizeof(host), port, sizeof(port),
                NI_NUMERICHOST|NI_NUMERICSERV);
	fds->statePtr->acceptProc(fds->statePtr->acceptProcData,
                newSockState->channel, host, atoi(port));
    }
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 */