summaryrefslogtreecommitdiffstats
path: root/win/tclWinSock.c
blob: f06aad1e241fc8e85c9241faec6712e108869eaa (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
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
/*
 * tclWinSock.c --
 *
 *	This file contains Windows-specific socket related code.
 *
 * Copyright (c) 1995-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution of
 * this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * -----------------------------------------------------------------------
 *
 * General information on how this module works.
 *
 * - Each Tcl-thread with its sockets maintains an internal window to receive
 *   socket messages from the OS.
 *
 * - To ensure that message reception is always running this window is
 *   actually owned and handled by an internal thread. This we call the
 *   co-thread of Tcl's thread.
 *
 * - The whole structure is set up by InitSockets() which is called for each
 *   Tcl thread. The implementation of the co-thread is in SocketThread(),
 *   and the messages are handled by SocketProc(). The connection between
 *   both is not directly visible, it is done through a Win32 window class.
 *   This class is initialized by InitSockets() as well, and used in the
 *   creation of the message receiver windows.
 *
 * - An important thing to note is that *both* thread and co-thread have
 *   access to the list of sockets maintained in the private TSD data of the
 *   thread. The co-thread was given access to it upon creation through the
 *   new thread's client-data.
 *
 *   Because of this dual access the TSD data contains an OS mutex, the
 *   "socketListLock", to mediate exclusion between thread and co-thread.
 *
 *   The co-thread's access is all in SocketProc(). The thread's access is
 *   through SocketEventProc() (1) and the functions called by it.
 *
 *   (Ad 1) This is the handler function for all queued socket events, which
 *          all the OS messages are translated to through the EventSource (2)
 *          driven by the OS messages.
 *
 *   (Ad 2) The main functions for this are SocketSetupProc() and
 *          SocketCheckProc().
 */

#include "tclWinInt.h"

#define DEBUGGING
#ifdef DEBUGGING
#define DEBUG(x) fprintf(stderr, ">>> %p %s(%d): %s<<<\n", \
			    infoPtr, __FUNCTION__, __LINE__, x)
#else
#define DEBUG(x)
#endif

/*
 * Which version of the winsock API do we want?
 */

#define WSA_VERSION_MAJOR	1
#define WSA_VERSION_MINOR	1

#ifdef _MSC_VER
#   pragma comment (lib, "ws2_32")
#endif

/*
 * Support for control over sockets' KEEPALIVE and NODELAY behavior is
 * currently disabled.
 */

#undef TCL_FEATURE_KEEPALIVE_NAGLE

/*
 * Make sure to remove the redirection defines set in tclWinPort.h that is in
 * use in other sections of the core, except for us.
 */

#undef getservbyname
#undef getsockopt
#undef setsockopt

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

/*
 * The following variable is used to tell whether this module has been
 * initialized.  If 1, initialization of sockets was successful, if -1 then
 * socket initialization failed (WSAStartup failed).
 */

static int initialized = 0;
static const TCHAR classname[] = TEXT("TclSocket");
TCL_DECLARE_MUTEX(socketMutex)

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

static TclInitProcessGlobalValueProc InitializeHostName;
static ProcessGlobalValue hostName = {
    0, 0, NULL, NULL, InitializeHostName, NULL, NULL
};

/*
 * The following defines declare the messages used on socket windows.
 */

#define SOCKET_MESSAGE		WM_USER+1
#define SOCKET_SELECT		WM_USER+2
#define SOCKET_TERMINATE	WM_USER+3
#define SELECT			TRUE
#define UNSELECT		FALSE

/*
 * 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;

#ifndef IN6_ARE_ADDR_EQUAL
#define IN6_ARE_ADDR_EQUAL IN6_ADDR_EQUAL
#endif

typedef struct SocketInfo SocketInfo;

typedef struct TcpFdList {
    SocketInfo *infoPtr;
    SOCKET fd;
    struct TcpFdList *next;
} TcpFdList;

/*
 * The following structure is used to store the data associated with each
 * socket.
 */

struct SocketInfo {
    Tcl_Channel channel;	/* Channel associated with this socket. */
    struct TcpFdList *sockets;	/* Windows SOCKET handle. */
    int flags;			/* Bit field comprised of the flags described
				 * below. */
    int watchEvents;		/* OR'ed combination of FD_READ, FD_WRITE,
				 * FD_CLOSE, FD_ACCEPT and FD_CONNECT that
				 * indicate which events are interesting. */
    int readyEvents;		/* OR'ed combination of FD_READ, FD_WRITE,
				 * FD_CLOSE, FD_ACCEPT and FD_CONNECT that
				 * indicate which events have occurred. */
    int selectEvents;		/* OR'ed combination of FD_READ, FD_WRITE,
				 * FD_CLOSE, FD_ACCEPT and FD_CONNECT that
				 * indicate which events are currently being
				 * selected. */
    int acceptEventCount;	/* Count of the current number of FD_ACCEPTs
				 * that have arrived and not yet processed. */
    Tcl_TcpAcceptProc *acceptProc;
				/* Proc to call on accept. */
    ClientData acceptProcData;	/* The data for the accept proc. */
    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 status;                 /* Cache status of async socket. */
    int cachedBlocking;         /* Cache blocking mode of async socket. */
    int lastError;		/* Error code from last message. */
    struct SocketInfo *nextPtr;	/* The next socket on the per-thread socket
				 * list. */
};

/*
 * The following structure is what is added to the Tcl event queue when a
 * socket event occurs.
 */

typedef struct {
    Tcl_Event header;		/* Information that is standard for all
				 * events. */
    SOCKET socket;		/* Socket descriptor that is ready. Used to
				 * find the SocketInfo structure for the file
				 * (can't point directly to the SocketInfo
				 * structure because it could go away while
				 * the event is queued). */
} SocketEvent;

/*
 * This defines the minimum buffersize maintained by the kernel.
 */

#define TCP_BUFFER_SIZE 4096

/*
 * The following macros may be used to set the flags field of a SocketInfo
 * structure.
 */

#define SOCKET_ASYNC		(1<<0)	/* The socket is in blocking mode. */
#define SOCKET_EOF		(1<<1)	/* A zero read happened on the
					 * socket. */
#define SOCKET_ASYNC_CONNECT	(1<<2)	/* This socket uses async connect. */
#define SOCKET_PENDING		(1<<3)	/* A message has been sent for this
					 * socket */

typedef struct {
    HWND hwnd;			/* Handle to window for socket messages. */
    HANDLE socketThread;	/* Thread handling the window */
    Tcl_ThreadId threadId;	/* Parent thread. */
    HANDLE readyEvent;		/* Event indicating that a socket event is
				 * ready. Also used to indicate that the
				 * socketThread has been initialized and has
				 * started. */
    HANDLE socketListLock;	/* Win32 Event to lock the socketList */
    SocketInfo *socketList;	/* Every open socket in this thread has an
				 * entry on this list. */
} ThreadSpecificData;

static Tcl_ThreadDataKey dataKey;
static WNDCLASS windowClass;

/*
 * Static functions defined in this file.
 */

static int		CreateClientSocket(Tcl_Interp *interp, SocketInfo *infoPtr);
static void		InitSockets(void);
static SocketInfo *	NewSocketInfo(SOCKET socket);
static void		SocketExitHandler(ClientData clientData);
static LRESULT CALLBACK	SocketProc(HWND hwnd, UINT message, WPARAM wParam,
			    LPARAM lParam);
static int		SocketsEnabled(void);
static void		TcpAccept(TcpFdList *fds, SOCKET newSocket, address addr);
static int		WaitForSocketEvent(SocketInfo *infoPtr, int events,
			    int *errorCodePtr);
static DWORD WINAPI	SocketThread(LPVOID arg);
static void		TcpThreadActionProc(ClientData instanceData,
			    int action);

static Tcl_EventCheckProc	SocketCheckProc;
static Tcl_EventProc		SocketEventProc;
static Tcl_EventSetupProc	SocketSetupProc;
static Tcl_DriverBlockModeProc	TcpBlockProc;
static Tcl_DriverCloseProc	TcpCloseProc;
static Tcl_DriverClose2Proc	TcpClose2Proc;
static Tcl_DriverSetOptionProc	TcpSetOptionProc;
static Tcl_DriverGetOptionProc	TcpGetOptionProc;
static Tcl_DriverInputProc	TcpInputProc;
static Tcl_DriverOutputProc	TcpOutputProc;
static Tcl_DriverWatchProc	TcpWatchProc;
static Tcl_DriverGetHandleProc	TcpGetHandleProc;

/*
 * 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 */
    TcpCloseProc,	    /* Close proc. */
    TcpInputProc,	    /* Input proc. */
    TcpOutputProc,	    /* Output proc. */
    NULL,		    /* Seek proc. */
    TcpSetOptionProc,	    /* Set option proc. */
    TcpGetOptionProc,	    /* Get option proc. */
    TcpWatchProc,	    /* Set up notifier to watch this channel. */
    TcpGetHandleProc,	    /* Get an OS handle from channel. */
    TcpClose2Proc,	    /* Close2proc. */
    TcpBlockProc,	    /* Set socket into (non-)blocking mode. */
    NULL,		    /* flush proc. */
    NULL,		    /* handler proc. */
    NULL,		    /* wide seek proc */
    TcpThreadActionProc,    /* thread action proc */
    NULL		    /* truncate */
};
void printaddrinfo(struct addrinfo *ai, char *prefix)
{
    char host[NI_MAXHOST], port[NI_MAXSERV];
    getnameinfo(ai->ai_addr, ai->ai_addrlen,
		host, sizeof(host),
		port, sizeof(port),
		NI_NUMERICHOST|NI_NUMERICSERV);
#ifdef DEBUGGING
    fprintf(stderr,"%s: [%s]:%s\n", prefix, host, port);
#endif
}
void printaddrinfolist(struct addrinfo *addrlist, char *prefix)
{
    struct addrinfo *ai;
    for (ai = addrlist; ai != NULL; ai = ai->ai_next) {
	printaddrinfo(ai, prefix);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * InitSockets --
 *
 *	Initialize the socket module.  If winsock startup is successful,
 *	registers the event window for the socket notifier code.
 *
 *	Assumes socketMutex is held.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Initializes winsock, registers a new window class and creates a
 *	window for use in asynchronous socket notification.
 *
 *----------------------------------------------------------------------
 */

static void
InitSockets(void)
{
    DWORD id, err;
    WSADATA wsaData;
    ThreadSpecificData *tsdPtr = TclThreadDataKeyGet(&dataKey);

    if (!initialized) {
	initialized = 1;
	TclCreateLateExitHandler(SocketExitHandler, NULL);

	/*
	 * Create the async notification window with a new class. We must
	 * create a new class to avoid a Windows 95 bug that causes us to get
	 * the wrong message number for socket events if the message window is
	 * a subclass of a static control.
	 */

	windowClass.style = 0;
	windowClass.cbClsExtra = 0;
	windowClass.cbWndExtra = 0;
	windowClass.hInstance = TclWinGetTclInstance();
	windowClass.hbrBackground = NULL;
	windowClass.lpszMenuName = NULL;
	windowClass.lpszClassName = classname;
	windowClass.lpfnWndProc = SocketProc;
	windowClass.hIcon = NULL;
	windowClass.hCursor = NULL;

	if (!RegisterClass(&windowClass)) {
	    TclWinConvertError(GetLastError());
	    goto initFailure;
	}

	/*
	 * Initialize the winsock library and check the interface version
	 * actually loaded. We only ask for the 1.1 interface and do require
	 * that it not be less than 1.1.
	 */

	err = WSAStartup((WORD) MAKEWORD(WSA_VERSION_MAJOR,WSA_VERSION_MINOR),
		&wsaData);
	if (err != 0) {
	    TclWinConvertError(err);
	    goto initFailure;
	}

	/*
	 * Note the byte positions ae swapped for the comparison, so that
	 * 0x0002 (2.0, MAKEWORD(2,0)) doesn't look less than 0x0101 (1.1). We
	 * want the comparison to be 0x0200 < 0x0101.
	 */

	if (MAKEWORD(HIBYTE(wsaData.wVersion), LOBYTE(wsaData.wVersion))
		< MAKEWORD(WSA_VERSION_MINOR, WSA_VERSION_MAJOR)) {
	    TclWinConvertError(WSAVERNOTSUPPORTED);
	    WSACleanup();
	    goto initFailure;
	}
    }

    /*
     * Check for per-thread initialization.
     */

    if (tsdPtr != NULL) {
	return;
    }

    /*
     * OK, this thread has never done anything with sockets before.  Construct
     * a worker thread to handle asynchronous events related to sockets
     * assigned to _this_ thread.
     */

    tsdPtr = TCL_TSD_INIT(&dataKey);
    tsdPtr->socketList = NULL;
    tsdPtr->hwnd       = NULL;
    tsdPtr->threadId   = Tcl_GetCurrentThread();
    tsdPtr->readyEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
    if (tsdPtr->readyEvent == NULL) {
	goto initFailure;
    }
    tsdPtr->socketListLock = CreateEvent(NULL, FALSE, TRUE, NULL);
    if (tsdPtr->socketListLock == NULL) {
	goto initFailure;
    }
    tsdPtr->socketThread = CreateThread(NULL, 256, SocketThread, tsdPtr, 0,
	    &id);
    if (tsdPtr->socketThread == NULL) {
	goto initFailure;
    }

    SetThreadPriority(tsdPtr->socketThread, THREAD_PRIORITY_HIGHEST);

    /*
     * Wait for the thread to signal when the window has been created and if
     * it is ready to go.
     */

    WaitForSingleObject(tsdPtr->readyEvent, INFINITE);

    if (tsdPtr->hwnd == NULL) {
	goto initFailure;	/* Trouble creating the window. */
    }

    Tcl_CreateEventSource(SocketSetupProc, SocketCheckProc, NULL);
    return;

  initFailure:
    TclpFinalizeSockets();
    initialized = -1;
    return;
}

/*
 *----------------------------------------------------------------------
 *
 * SocketsEnabled --
 *
 *	Check that the WinSock was successfully initialized.
 *
 * Results:
 *	1 if it is.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

    /* ARGSUSED */
static int
SocketsEnabled(void)
{
    int enabled;

    Tcl_MutexLock(&socketMutex);
    enabled = (initialized == 1);
    Tcl_MutexUnlock(&socketMutex);
    return enabled;
}


/*
 *----------------------------------------------------------------------
 *
 * SocketExitHandler --
 *
 *	Callback invoked during exit clean up to delete the socket
 *	communication window and to release the WinSock DLL.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

    /* ARGSUSED */
static void
SocketExitHandler(
    ClientData clientData)		/* Not used. */
{
    Tcl_MutexLock(&socketMutex);

    /*
     * Make sure the socket event handling window is cleaned-up for, at
     * most, this thread.
     */

    TclpFinalizeSockets();
    UnregisterClass(classname, TclWinGetTclInstance());
    WSACleanup();
    initialized = 0;
    Tcl_MutexUnlock(&socketMutex);
}

/*
 *----------------------------------------------------------------------
 *
 * TclpFinalizeSockets --
 *
 *	This function is called from Tcl_FinalizeThread to finalize the
 *	platform specific socket subsystem. Also, it may be called from within
 *	this module to cleanup the state if unable to initialize the sockets
 *	subsystem.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Deletes the event source and destroys the socket thread.
 *
 *----------------------------------------------------------------------
 */

void
TclpFinalizeSockets(void)
{
    ThreadSpecificData *tsdPtr = TclThreadDataKeyGet(&dataKey);

    /*
     * Careful! This is a finalizer!
     */

    if (tsdPtr == NULL) {
	return;
    }

    if (tsdPtr->socketThread != NULL) {
	if (tsdPtr->hwnd != NULL) {
	    PostMessage(tsdPtr->hwnd, SOCKET_TERMINATE, 0, 0);

	    /*
	     * Wait for the thread to exit. This ensures that we are
	     * completely cleaned up before we leave this function.
	     */

	    WaitForSingleObject(tsdPtr->readyEvent, INFINITE);
	    tsdPtr->hwnd = NULL;
	}
	CloseHandle(tsdPtr->socketThread);
	tsdPtr->socketThread = NULL;
    }
    if (tsdPtr->readyEvent != NULL) {
	CloseHandle(tsdPtr->readyEvent);
	tsdPtr->readyEvent = NULL;
    }
    if (tsdPtr->socketListLock != NULL) {
	CloseHandle(tsdPtr->socketListLock);
	tsdPtr->socketListLock = NULL;
    }
    Tcl_DeleteEventSource(SocketSetupProc, SocketCheckProc, NULL);
}

/*
 *----------------------------------------------------------------------
 *
 * TclpHasSockets --
 *
 *	This function determines whether sockets are available on the current
 *	system and returns an error in interp if they are not. Note that
 *	interp may be NULL.
 *
 * Results:
 *	Returns TCL_OK if the system supports sockets, or TCL_ERROR with an
 *	error in interp (if non-NULL).
 *
 * Side effects:
 *	If not already prepared, initializes the TSD structure and socket
 *	message handling thread associated to the calling thread for the
 *	subsystem of the driver.
 *
 *----------------------------------------------------------------------
 */

int
TclpHasSockets(
    Tcl_Interp *interp)		/* Where to write an error message if sockets
				 * are not present, or NULL if no such message
				 * is to be written. */
{
    Tcl_MutexLock(&socketMutex);
    InitSockets();
    Tcl_MutexUnlock(&socketMutex);

    if (SocketsEnabled()) {
	return TCL_OK;
    }
    if (interp != NULL) {
	Tcl_SetObjResult(interp, Tcl_NewStringObj(
		"sockets are not available on this system", -1));
    }
    return TCL_ERROR;
}

/*
 *----------------------------------------------------------------------
 *
 * SocketSetupProc --
 *
 *	This function is invoked before Tcl_DoOneEvent blocks waiting for an
 *	event.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Adjusts the block time if needed.
 *
 *----------------------------------------------------------------------
 */

void
SocketSetupProc(
    ClientData data,		/* Not used. */
    int flags)			/* Event flags as passed to Tcl_DoOneEvent. */
{
    SocketInfo *infoPtr;
    Tcl_Time blockTime = { 0, 0 };
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    if (!(flags & TCL_FILE_EVENTS)) {
	return;
    }

    /*
     * Check to see if there is a ready socket.	 If so, poll.
     */
    WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
    for (infoPtr = tsdPtr->socketList; infoPtr != NULL;
	    infoPtr = infoPtr->nextPtr) {
	if (infoPtr->readyEvents &
	    (infoPtr->watchEvents | FD_CONNECT | FD_ACCEPT)
	) {
	    DEBUG("Tcl_SetMaxBlockTime");
	    Tcl_SetMaxBlockTime(&blockTime);
	    break;
	}
    }
    SetEvent(tsdPtr->socketListLock);
}

/*
 *----------------------------------------------------------------------
 *
 * SocketCheckProc --
 *
 *	This function is called by Tcl_DoOneEvent to check the socket event
 *	source for events.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	May queue an event.
 *
 *----------------------------------------------------------------------
 */

static void
SocketCheckProc(
    ClientData data,		/* Not used. */
    int flags)			/* Event flags as passed to Tcl_DoOneEvent. */
{
    SocketInfo *infoPtr;
    SocketEvent *evPtr;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);

    if (!(flags & TCL_FILE_EVENTS)) {
	return;
    }

    /*
     * Queue events for any ready sockets that don't already have events
     * queued (caused by persistent states that won't generate WinSock
     * events).
     */

    WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
    for (infoPtr = tsdPtr->socketList; infoPtr != NULL;
	    infoPtr = infoPtr->nextPtr) {
    DEBUG("A");
	if ((infoPtr->readyEvents &
		(infoPtr->watchEvents | FD_CONNECT | FD_ACCEPT))
	    && !(infoPtr->flags & SOCKET_PENDING)
	) {
    DEBUG("B");
	    infoPtr->flags |= SOCKET_PENDING;
	    evPtr = ckalloc(sizeof(SocketEvent));
	    evPtr->header.proc = SocketEventProc;
	    evPtr->socket = infoPtr->sockets->fd;
	    Tcl_QueueEvent((Tcl_Event *) evPtr, TCL_QUEUE_TAIL);
	}
    }
    SetEvent(tsdPtr->socketListLock);
}

/*
 *----------------------------------------------------------------------
 *
 * SocketEventProc --
 *
 *	This function is called by Tcl_ServiceEvent when a socket event
 *	reaches the front of the event queue. This function is responsible for
 *	notifying the generic channel code.
 *
 * Results:
 *	Returns 1 if the event was handled, meaning it should be removed from
 *	the queue. Returns 0 if the event was not handled, meaning it should
 *	stay on the queue. The only time the event isn't handled is if the
 *	TCL_FILE_EVENTS flag bit isn't set.
 *
 * Side effects:
 *	Whatever the channel callback functions do.
 *
 *----------------------------------------------------------------------
 */

static int
SocketEventProc(
    Tcl_Event *evPtr,		/* Event to service. */
    int flags)			/* Flags that indicate what events to handle,
				 * such as TCL_FILE_EVENTS. */
{
    SocketInfo *infoPtr = NULL; /* DEBUG */
    SocketEvent *eventPtr = (SocketEvent *) evPtr;
    int mask = 0, events;
    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
    TcpFdList *fds;
    SOCKET newSocket;
    address addr;
    int len;

    DEBUG("");
    if (!(flags & TCL_FILE_EVENTS)) {
	return 0;
    }

    /*
     * Find the specified socket on the socket list.
     */

    WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
    for (infoPtr = tsdPtr->socketList; infoPtr != NULL;
	    infoPtr = infoPtr->nextPtr) {
	if (infoPtr->sockets->fd == eventPtr->socket) {
	    break;
	}
    }

    /*
     * Discard events that have gone stale.
     */

    if (!infoPtr) {
        SetEvent(tsdPtr->socketListLock);
	return 1;
    }

    infoPtr->flags &= ~SOCKET_PENDING;

    if (infoPtr->readyEvents & FD_CONNECT) {
	DEBUG("FD_CONNECT");
	SetEvent(tsdPtr->socketListLock);
	CreateClientSocket(NULL, infoPtr);
	infoPtr->readyEvents &= ~(FD_CONNECT);
	return 1;
    }

    /*
     * Handle connection requests directly.
     */
    if (infoPtr->readyEvents & FD_ACCEPT) {
	for (fds = infoPtr->sockets; fds != NULL; fds = fds->next) {

	    /*
	    * Accept the incoming connection request.
	    */
	    len = sizeof(address);

	    newSocket = accept(fds->fd, &(addr.sa), &len);

	    /* On Tcl server sockets with multiple OS fds we loop over the fds trying
	     * an accept() on each, so we expect INVALID_SOCKET.  There are also other
	     * network stack conditions that can result in FD_ACCEPT but a subsequent
	     * failure on accept() by the time we get around to it.
	     * Access to sockets (acceptEventCount, readyEvents) in socketList
	     * is still protected by the lock (prevents reintroduction of 
	     * SF Tcl Bug 3056775.
	     */

	    if (newSocket == INVALID_SOCKET) {
		/* int err = WSAGetLastError(); */
		continue;
	    }

	    /*
	     * It is possible that more than one FD_ACCEPT has been sent, so an extra
	     * count must be kept. Decrement the count, and reset the readyEvent bit
	     * if the count is no longer > 0.
	     */
	    infoPtr->acceptEventCount--;

	    if (infoPtr->acceptEventCount <= 0) {
		infoPtr->readyEvents &= ~(FD_ACCEPT);
	    }

	    SetEvent(tsdPtr->socketListLock);

	    /* Caution: TcpAccept() has the side-effect of evaluating the server
	     * accept script (via AcceptCallbackProc() in tclIOCmd.c), which can
	     * close the server socket and invalidate infoPtr and fds.
	     * If TcpAccept() accepts a socket we must return immediately and let
	     * SocketCheckProc queue additional FD_ACCEPT events.
	     */
	    TcpAccept(fds, newSocket, addr);
	    return 1;
	}

	/* Loop terminated with no sockets accepted; clear the ready mask so 
	 * we can detect the next connection request. Note that connection 
	 * requests are level triggered, so if there is a request already 
	 * pending, a new event will be generated.
	 */
	infoPtr->acceptEventCount = 0;
	infoPtr->readyEvents &= ~(FD_ACCEPT);

	SetEvent(tsdPtr->socketListLock);
	return 1;
    }

    SetEvent(tsdPtr->socketListLock);

    /*
     * Mask off unwanted events and compute the read/write mask so we can
     * notify the channel.
     */

    events = infoPtr->readyEvents & infoPtr->watchEvents;

    if (events & FD_CLOSE) {
	/*
	 * If the socket was closed and the channel is still interested in
	 * read events, then we need to ensure that we keep polling for this
	 * event until someone does something with the channel. Note that we
	 * do this before calling Tcl_NotifyChannel so we don't have to watch
	 * out for the channel being deleted out from under us. This may cause
	 * a redundant trip through the event loop, but it's simpler than
	 * trying to do unwind protection.
	 */

	Tcl_Time blockTime = { 0, 0 };

	DEBUG("FD_CLOSE");
	Tcl_SetMaxBlockTime(&blockTime);
	mask |= TCL_READABLE|TCL_WRITABLE;
    } else if (events & FD_READ) {
	fd_set readFds;
	struct timeval timeout;

	/*
	 * We must check to see if data is really available, since someone
	 * could have consumed the data in the meantime. Turn off async
	 * notification so select will work correctly. If the socket is still
	 * readable, notify the channel driver, otherwise reset the async
	 * select handler and keep waiting.
	 */
	DEBUG("FD_READ");

	SendMessage(tsdPtr->hwnd, SOCKET_SELECT,
		(WPARAM) UNSELECT, (LPARAM) infoPtr);

	FD_ZERO(&readFds);
	FD_SET(infoPtr->sockets->fd, &readFds);
	timeout.tv_usec = 0;
	timeout.tv_sec = 0;

	if (select(0, &readFds, NULL, NULL, &timeout) != 0) {
	    mask |= TCL_READABLE;
	} else {
	    infoPtr->readyEvents &= ~(FD_READ);
	    SendMessage(tsdPtr->hwnd, SOCKET_SELECT,
		    (WPARAM) SELECT, (LPARAM) infoPtr);
	}
    }
    if (events & FD_WRITE) {
	DEBUG("FD_WRITE");
	mask |= TCL_WRITABLE;
    }
    if (mask) {
	DEBUG("Calling Tcl_NotifyChannel...");
	Tcl_NotifyChannel(infoPtr->channel, mask);
    }
    DEBUG("returning...");
    return 1;
}

/*
 *----------------------------------------------------------------------
 *
 * TcpBlockProc --
 *
 *	Sets a socket into blocking or non-blocking mode.
 *
 * Results:
 *	0 if successful, errno if there was an error.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
TcpBlockProc(
    ClientData instanceData,	/* The socket to block/un-block. */
    int mode)			/* TCL_MODE_BLOCKING or
				 * TCL_MODE_NONBLOCKING. */
{
    SocketInfo *infoPtr = instanceData;

    if (mode == TCL_MODE_NONBLOCKING) {
	infoPtr->flags |= SOCKET_ASYNC;
    } else {
	infoPtr->flags &= ~(SOCKET_ASYNC);
    }
    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * TcpCloseProc --
 *
 *	This function is called by the generic IO level to perform channel
 *	type specific cleanup on a socket based channel when the channel is
 *	closed.
 *
 * Results:
 *	0 if successful, the value of errno if failed.
 *
 * Side effects:
 *	Closes the socket.
 *
 *----------------------------------------------------------------------
 */

    /* ARGSUSED */
static int
TcpCloseProc(
    ClientData instanceData,	/* The socket to close. */
    Tcl_Interp *interp)		/* Unused. */
{
    SocketInfo *infoPtr = instanceData;
    /* TIP #218 */
    int errorCode = 0;
    /* ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey); */

    /*
     * Check that WinSock is initialized; do not call it if not, to prevent
     * system crashes. This can happen at exit time if the exit handler for
     * WinSock ran before other exit handlers that want to use sockets.
     */

    if (SocketsEnabled()) {
	/*
	 * Clean up the OS socket handle. The default Windows setting for a
	 * socket is SO_DONTLINGER, which does a graceful shutdown in the
	 * background.
	 */

	while ( infoPtr->sockets != NULL ) {
	    TcpFdList *thisfd = infoPtr->sockets;
	    infoPtr->sockets = thisfd->next;

	    if (closesocket(thisfd->fd) == SOCKET_ERROR) {
		TclWinConvertError((DWORD) WSAGetLastError());
		errorCode = Tcl_GetErrno();
	    }
	    ckfree(thisfd);
	}
    }

    if (infoPtr->addrlist != NULL) {
        freeaddrinfo(infoPtr->addrlist);
    }
    if (infoPtr->myaddrlist != NULL) {
        freeaddrinfo(infoPtr->myaddrlist);
    }

    /*
     * TIP #218. Removed the code removing the structure from the global
     * socket list. This is now done by the thread action callbacks, and only
     * there. This happens before this code is called. We can free without
     * fear of damaging the list.
     */

    ckfree(infoPtr);
    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(
    ClientData instanceData,	/* The socket to close. */
    Tcl_Interp *interp,		/* For error reporting. */
    int flags)			/* Flags that indicate which side to close. */
{
    SocketInfo *infoPtr = instanceData;
    int errorCode = 0, sd;

    /*
     * Shutdown the OS socket handle.
     */

    switch (flags) {
    case TCL_CLOSE_READ:
	sd = SD_RECEIVE;
	break;
    case TCL_CLOSE_WRITE:
	sd = SD_SEND;
	break;
    default:
	if (interp) {
	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
		    "Socket close2proc called bidirectionally", -1));
	}
	return TCL_ERROR;
    }

    /* single fd operation: Tcl_OpenTcpServer() does not set TCL_READABLE or
     * TCL_WRITABLE so this should never be called for a server socket. */
    if (shutdown(infoPtr->sockets->fd, sd) == SOCKET_ERROR) {
	TclWinConvertError((DWORD) WSAGetLastError());
	errorCode = Tcl_GetErrno();
    }

    return errorCode;
}

/*
 *----------------------------------------------------------------------
 *
 * AddSocketInfoFd --
 *
 *	This function adds a SOCKET file descriptor to the 'sockets' linked 
 *	list of a SocketInfo structure.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	None, except for allocation of memory.
 *
 *----------------------------------------------------------------------
 */

static void
AddSocketInfoFd(
    SocketInfo *infoPtr, 
    SOCKET socket)
{
    TcpFdList *fds = infoPtr->sockets;

    if ( fds == NULL ) {
	/* Add the first FD */
	infoPtr->sockets = ckalloc(sizeof(TcpFdList));
	fds = infoPtr->sockets;
    } else {
	/* Find end of list and append FD */
	while ( fds->next != NULL ) {
	    fds = fds->next;
	}
    
	fds->next = ckalloc(sizeof(TcpFdList));
	fds = fds->next;
    }

    /* Populate new FD */
    fds->fd = socket;
    fds->infoPtr = infoPtr;
    fds->next = NULL;
}

    
/*
 *----------------------------------------------------------------------
 *
 * NewSocketInfo --
 *
 *	This function allocates and initializes a new SocketInfo structure.
 *
 * Results:
 *	Returns a newly allocated SocketInfo.
 *
 * Side effects:
 *	None, except for allocation of memory.
 *
 *----------------------------------------------------------------------
 */

static SocketInfo *
NewSocketInfo(SOCKET socket)
{
    SocketInfo *infoPtr = ckalloc(sizeof(SocketInfo));

    memset(infoPtr, 0, sizeof(SocketInfo));

    /*
     * TIP #218. Removed the code inserting the new structure into the global
     * list. This is now handled in the thread action callbacks, and only
     * there.
     */

    AddSocketInfoFd(infoPtr, socket);

    return infoPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * CreateClientSocket --
 *
 *	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 asyncronously 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 syncronously connecting sockets, the loops work the usual way.
 *
 *----------------------------------------------------------------------
 */

static int
CreateClientSocket(
    Tcl_Interp *interp,		/* For error reporting; can be NULL. */
    SocketInfo *infoPtr)
{
    u_long flag = 1;		/* Indicates nonblocking mode. */
    int async = infoPtr->flags & SOCKET_ASYNC_CONNECT;
    int async_callback = infoPtr->sockets->fd != INVALID_SOCKET;
    ThreadSpecificData *tsdPtr;
    
    DEBUG(async ? "async" : "sync");

    if (async_callback) {
	DEBUG("subsequent call");
        goto reenter;
    } else {
	DEBUG("first call");
    }
    
    for (infoPtr->addr = infoPtr->addrlist; infoPtr->addr != NULL;
	 infoPtr->addr = infoPtr->addr->ai_next) {
	
        for (infoPtr->myaddr = infoPtr->myaddrlist; infoPtr->myaddr != NULL;
	     infoPtr->myaddr = infoPtr->myaddr->ai_next) {

	    DEBUG("inner loop");

	    /*
	     * No need to try combinations of local and remote addresses
	     * of different families.
	     */

	    if (infoPtr->myaddr->ai_family != infoPtr->addr->ai_family) {
		DEBUG("family mismatch");
		continue;
	    }

	    DEBUG(infoPtr->myaddr->ai_family == AF_INET ? "IPv4" : "IPv6");
	    printaddrinfo(infoPtr->myaddr, "~~ from");
	    printaddrinfo(infoPtr->addr,   "~~   to");

            /*
             * Close the socket if it is still open from the last unsuccessful
             * iteration.
             */	    
	    if (infoPtr->sockets->fd != INVALID_SOCKET) {
		DEBUG("closesocket");
		closesocket(infoPtr->sockets->fd);
	    }

	    /*
	     * Reset last error from last try
	     */
	    infoPtr->lastError = 0;
	    
	    infoPtr->sockets->fd = socket(infoPtr->myaddr->ai_family, SOCK_STREAM, 0);
	    if (infoPtr->sockets->fd == INVALID_SOCKET) {
		DEBUG("socket() failed");
		TclWinConvertError((DWORD) WSAGetLastError());
		continue;
	    }
	    
	    /*
	     * Win-NT has a misfeature that sockets are inherited in child
	     * processes by default. Turn off the inherit bit.
	     */

	    SetHandleInformation((HANDLE) infoPtr->sockets->fd, HANDLE_FLAG_INHERIT, 0);

	    /*
	     * Set kernel space buffering
	     */

	    TclSockMinimumBuffers((void *) infoPtr->sockets->fd, TCP_BUFFER_SIZE);

	    /*
	     * Try to bind to a local port.
	     */

	    if (bind(infoPtr->sockets->fd, infoPtr->myaddr->ai_addr,
			infoPtr->myaddr->ai_addrlen) == SOCKET_ERROR) {
		DEBUG("bind() failed");
		TclWinConvertError((DWORD) WSAGetLastError());
		continue;
	    }
	    /*
	     * Set the socket into nonblocking mode if the connect should
	     * be done in the background.
	     */
	    if (async) {
		ThreadSpecificData *tsdPtr = TclThreadDataKeyGet(&dataKey);
		infoPtr->selectEvents |= FD_CONNECT;

		ioctlsocket(infoPtr->sockets->fd, (long) FIONBIO, &flag);
		SendMessage(tsdPtr->hwnd, SOCKET_SELECT, (WPARAM) SELECT,
			    (LPARAM) infoPtr);
	    }

	    /*
	     * Attempt to connect to the remote socket.
	     */

	    if (connect(infoPtr->sockets->fd, infoPtr->addr->ai_addr,
			    infoPtr->addr->ai_addrlen) == SOCKET_ERROR) {
		DWORD error = (DWORD) WSAGetLastError();
		TclWinConvertError(error);
		DEBUG("connect()");
#ifdef DEBUGGING
		// fprintf(stderr,"error = %lu\n", error);
#endif
		if (error == WSAEWOULDBLOCK) {
		    DEBUG("WSAEWOULDBLOCK");
		    return TCL_OK;
		reenter:
		    Tcl_SetErrno(infoPtr->lastError);
		    DEBUG("reenter");
		    infoPtr->selectEvents &= ~(FD_CONNECT);
		}
	    } else {
		DWORD error = (DWORD) WSAGetLastError();
		TclWinConvertError(error);
	    }
#ifdef DEBUGGING
	    fprintf(stderr, "lastError: %d\n", Tcl_GetErrno());
#endif
	    if (Tcl_GetErrno() == 0) {
		goto out;
	    }
	}
    }

out:
    DEBUG("connected or finally failed");
    if (Tcl_GetErrno() != 0 && interp != NULL) {
	DEBUG("ERRNO");
	if (interp != NULL) {
	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
				"couldn't open socket: %s", Tcl_PosixError(interp)));
	}
	return TCL_ERROR;
    }
    /*
     * Set up the select mask for read/write events.
     */
    
    infoPtr->selectEvents = FD_READ | FD_WRITE | FD_CLOSE;
    
    /*
     * Register for interest in events in the select mask. Note that this
     * automatically places the socket into non-blocking mode.
     */
    
    tsdPtr = TclThreadDataKeyGet(&dataKey);
    ioctlsocket(infoPtr->sockets->fd, (long) FIONBIO, &flag);
    SendMessage(tsdPtr->hwnd, SOCKET_SELECT, (WPARAM) SELECT,
		(LPARAM) infoPtr);
    if (async_callback) {
	Tcl_NotifyChannel(infoPtr->channel, TCL_WRITABLE);
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * WaitForSocketEvent --
 *
 *	Waits until one of the specified events occurs on a socket.
 *
 * Results:
 *	Returns 1 on success or 0 on failure, with an error code in
 *	errorCodePtr.
 *
 * Side effects:
 *	Processes socket events off the system queue.
 *
 *----------------------------------------------------------------------
 */

static int
WaitForSocketEvent(
    SocketInfo *infoPtr,	/* Information about this socket. */
    int events,			/* Events to look for. */
    int *errorCodePtr)		/* Where to store errors? */
{
    int result = 1;
    int oldMode;
    ThreadSpecificData *tsdPtr = TclThreadDataKeyGet(&dataKey);
    /*
     * Be sure to disable event servicing so we are truly modal.
     */
    DEBUG("=============");

    oldMode = Tcl_SetServiceMode(TCL_SERVICE_NONE);

    /*
     * Reset WSAAsyncSelect so we have a fresh set of events pending.
     */

    SendMessage(tsdPtr->hwnd, SOCKET_SELECT, (WPARAM) UNSELECT,
	    (LPARAM) infoPtr);
    SendMessage(tsdPtr->hwnd, SOCKET_SELECT, (WPARAM) SELECT,
	    (LPARAM) infoPtr);

    while (1) {
	if (infoPtr->lastError) {
	    *errorCodePtr = infoPtr->lastError;
	    result = 0;
	    break;
	} else if (infoPtr->readyEvents & events) {
	    break;
	} else if (infoPtr->flags & SOCKET_ASYNC) {
	    *errorCodePtr = EWOULDBLOCK;
	    result = 0;
	    break;
	}

	/*
	 * Wait until something happens.
	 */

	WaitForSingleObject(tsdPtr->readyEvent, INFINITE);
    }

    (void) Tcl_SetServiceMode(oldMode);
    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * 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, should connect client socket
				 * asynchronously. */
{
    SocketInfo *infoPtr;
    const char *errorMsg = NULL;
    struct addrinfo *addrlist = NULL;
    struct addrinfo *myaddrlist = NULL;
    char channelName[SOCK_CHAN_LENGTH];

    if (TclpHasSockets(interp) != TCL_OK) {
	return NULL;
    }

    /*
     * Check that WinSock is initialized; do not call it if not, to prevent
     * system crashes. This can happen at exit time if the exit handler for
     * WinSock ran before other exit handlers that want to use sockets.
     */

    if (!SocketsEnabled()) {
	return NULL;
    }

    /*
     * 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;
    }
    printaddrinfolist(myaddrlist, "local");
    printaddrinfolist(addrlist, "remote");

    infoPtr = NewSocketInfo(INVALID_SOCKET);
    infoPtr->addrlist = addrlist;
    infoPtr->myaddrlist = myaddrlist;
    if (async) {
	infoPtr->flags |= SOCKET_ASYNC_CONNECT;
    }

    /*
     * Create a new client socket and wrap it in a channel.
     */
    DEBUG("");
    if (CreateClientSocket(interp, infoPtr) != TCL_OK) {
	TcpCloseProc(infoPtr, NULL);
	return NULL;
    }

    sprintf(channelName, SOCK_TEMPLATE, infoPtr);

    infoPtr->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
	    infoPtr, (TCL_READABLE | TCL_WRITABLE));
    if (TCL_ERROR == Tcl_SetChannelOption(NULL, infoPtr->channel,
	    "-translation", "auto crlf")) {
	Tcl_Close(NULL, infoPtr->channel);
	return NULL;
    } else if (TCL_ERROR == Tcl_SetChannelOption(NULL, infoPtr->channel,
	    "-eofchar", "")) {
	Tcl_Close(NULL, infoPtr->channel);
	return NULL;
    }
    return infoPtr->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.
 *
 * NOTE: Code contributed by Mark Diekhans (markd@grizzly.com)
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
Tcl_MakeTcpClientChannel(
    ClientData sock)		/* The socket to wrap up into a channel. */
{
    SocketInfo *infoPtr;
    char channelName[SOCK_CHAN_LENGTH];
    ThreadSpecificData *tsdPtr;

    if (TclpHasSockets(NULL) != TCL_OK) {
	return NULL;
    }

    tsdPtr = TclThreadDataKeyGet(&dataKey);

    /*
     * Set kernel space buffering and non-blocking.
     */

    TclSockMinimumBuffers(sock, TCP_BUFFER_SIZE);

    infoPtr = NewSocketInfo((SOCKET) sock);

    /*
     * Start watching for read/write events on the socket.
     */

    infoPtr->selectEvents = FD_READ | FD_CLOSE | FD_WRITE;
    SendMessage(tsdPtr->hwnd, SOCKET_SELECT, (WPARAM)SELECT, (LPARAM)infoPtr);

    sprintf(channelName, SOCK_TEMPLATE, infoPtr);
    infoPtr->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
	    infoPtr, (TCL_READABLE | TCL_WRITABLE));
    Tcl_SetChannelOption(NULL, infoPtr->channel, "-translation", "auto crlf");
    return infoPtr->channel;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_OpenTcpServer --
 *
 *	Opens a TCP server 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 server socket and creates a new channel.
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
Tcl_OpenTcpServer(
    Tcl_Interp *interp,		/* For error reporting - may be NULL. */
    int port,			/* Port number to open. */
    const char *host,		/* Name of local host. */
    Tcl_TcpAcceptProc *acceptProc,
				/* Callback for accepting connections from new
				 * clients. */
    ClientData acceptProcData)	/* Data for the callback. */
{
    SOCKET sock = INVALID_SOCKET;
    unsigned short chosenport = 0;
    struct addrinfo *addrPtr;	/* Socket address to listen on. */
    SocketInfo *infoPtr = NULL;	/* The returned value. */
    struct addrinfo *addrlist = NULL;
    char channelName[SOCK_CHAN_LENGTH];
    u_long flag = 1;		/* Indicates nonblocking mode. */
    const char *errorMsg = NULL;
    ThreadSpecificData *tsdPtr = TclThreadDataKeyGet(&dataKey);

    if (TclpHasSockets(interp) != TCL_OK) {
	return NULL;
    }

    /*
     * Check that WinSock is initialized; do not call it if not, to prevent
     * system crashes. This can happen at exit time if the exit handler for
     * WinSock ran before other exit handlers that want to use sockets.
     */

    if (!SocketsEnabled()) {
	return NULL;
    }

    /*
     * Construct the addresses for each end of the socket.
     */

    if (!TclCreateSocketAddress(interp, &addrlist, host, port, 1, &errorMsg)) {
	goto error;
    }

    for (addrPtr = addrlist; addrPtr != NULL; addrPtr = addrPtr->ai_next) {
	sock = socket(addrPtr->ai_family, addrPtr->ai_socktype,
                addrPtr->ai_protocol);
	if (sock == INVALID_SOCKET) {
	    TclWinConvertError((DWORD) WSAGetLastError());
	    continue;
	}
	
	/*
	 * Win-NT has a misfeature that sockets are inherited in child
	 * processes by default. Turn off the inherit bit.
	 */
	
	SetHandleInformation((HANDLE) sock, HANDLE_FLAG_INHERIT, 0);
	
	/*
	 * Set kernel space buffering
	 */
	
	TclSockMinimumBuffers((void *)sock, TCP_BUFFER_SIZE);
	
	/*
	 * Make sure we use the same port when opening two server sockets
	 * for IPv4 and IPv6.
	 *
	 * 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);
	}
	
	/*
	 * Bind to the specified port. Note that we must not call
	 * setsockopt with SO_REUSEADDR because Microsoft allows addresses
	 * to be reused even if they are still in use.
	 *
	 * Bind should not be affected by the socket having already been
	 * set into nonblocking mode. If there is trouble, this is one
	 * place to look for bugs.
	 */
	
	if (bind(sock, addrPtr->ai_addr, addrPtr->ai_addrlen)
	    == SOCKET_ERROR) {
	    TclWinConvertError((DWORD) WSAGetLastError());
	    closesocket(sock);
	    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);
	    }
	}
	
	/*
	 * Set the maximum number of pending connect requests to the max
	 * value allowed on each platform (Win32 and Win32s may be
	 * different, and there may be differences between TCP/IP stacks).
	 */
	
	if (listen(sock, SOMAXCONN) == SOCKET_ERROR) {
	    TclWinConvertError((DWORD) WSAGetLastError());
	    closesocket(sock);
	    continue;
	}
	
	if (infoPtr == NULL) {
	    /*
	     * Add this socket to the global list of sockets.
	     */
	    infoPtr = NewSocketInfo(sock);
	} else {
	    AddSocketInfoFd( infoPtr, sock );
	}
    }

error:
     if (addrlist != NULL) {
	freeaddrinfo(addrlist);
    }

    if (infoPtr != NULL) {

	infoPtr->acceptProc = acceptProc;
	infoPtr->acceptProcData = acceptProcData;
	sprintf(channelName, SOCK_TEMPLATE, infoPtr);
	infoPtr->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
					    infoPtr, 0);	
	/*
	 * Set up the select mask for connection request events.
	 */
	
	infoPtr->selectEvents = FD_ACCEPT;
	
	/*
	 * Register for interest in events in the select mask. Note that this
	 * automatically places the socket into non-blocking mode.
	 */

	ioctlsocket(sock, (long) FIONBIO, &flag);
	SendMessage(tsdPtr->hwnd, SOCKET_SELECT, (WPARAM) SELECT,
		    (LPARAM) infoPtr);
	if (Tcl_SetChannelOption(interp, infoPtr->channel, "-eofchar", "")
	    == TCL_ERROR) {
	    Tcl_Close(NULL, infoPtr->channel);
	    return NULL;
	}
	return infoPtr->channel;
    }

    if (interp != NULL) {
        Tcl_SetObjResult(interp, Tcl_ObjPrintf(
		"couldn't open socket: %s",
		(errorMsg ? errorMsg : Tcl_PosixError(interp))));
    }

    if (sock != INVALID_SOCKET) {
	closesocket(sock);
    }
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * TcpAccept --
 *
 *	Creates a channel for a newly accepted socket connection. This is 
 *	called by SocketEventProc and it in turns calls the registered 
 *	accept function.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Invokes the accept proc which may invoke arbitrary Tcl code.
 *
 *----------------------------------------------------------------------
 */

static void
TcpAccept(
    TcpFdList *fds,	/* Server socket that accepted newSocket. */
    SOCKET newSocket,   /* Newly accepted socket. */
    address addr)       /* Address of new socket. */
{
    SocketInfo *newInfoPtr;
    SocketInfo *infoPtr = fds->infoPtr;
    int len = sizeof(addr);
    char channelName[SOCK_CHAN_LENGTH];
    char host[NI_MAXHOST], port[NI_MAXSERV];
    ThreadSpecificData *tsdPtr = TclThreadDataKeyGet(&dataKey);

    /*
     * Win-NT has a misfeature that sockets are inherited in child processes
     * by default. Turn off the inherit bit.
     */

    SetHandleInformation((HANDLE) newSocket, HANDLE_FLAG_INHERIT, 0);

    /*
     * Add this socket to the global list of sockets.
     */

    newInfoPtr = NewSocketInfo(newSocket);

    /*
     * Select on read/write events and create the channel.
     */

    newInfoPtr->selectEvents = (FD_READ | FD_WRITE | FD_CLOSE);
    SendMessage(tsdPtr->hwnd, SOCKET_SELECT, (WPARAM) SELECT,
	    (LPARAM) newInfoPtr);

    sprintf(channelName, SOCK_TEMPLATE, newInfoPtr);
    newInfoPtr->channel = Tcl_CreateChannel(&tcpChannelType, channelName,
	    newInfoPtr, (TCL_READABLE | TCL_WRITABLE));
    if (Tcl_SetChannelOption(NULL, newInfoPtr->channel, "-translation",
	    "auto crlf") == TCL_ERROR) {
	Tcl_Close(NULL, newInfoPtr->channel);
	return;
    }
    if (Tcl_SetChannelOption(NULL, newInfoPtr->channel, "-eofchar", "")
	    == TCL_ERROR) {
	Tcl_Close(NULL, newInfoPtr->channel);
	return;
    }

    /*
     * Invoke the accept callback function.
     */

    if (infoPtr->acceptProc != NULL) {
	getnameinfo(&(addr.sa), len, host, sizeof(host), port, sizeof(port),
                    NI_NUMERICHOST|NI_NUMERICSERV);
	infoPtr->acceptProc(infoPtr->acceptProcData, newInfoPtr->channel,
			    host, atoi(port));
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TcpInputProc --
 *
 *	This function is called by the generic IO level to read data from a
 *	socket based channel.
 *
 * Results:
 *	The number of bytes read or -1 on error.
 *
 * Side effects:
 *	Consumes input from the socket.
 *
 *----------------------------------------------------------------------
 */

static int
TcpInputProc(
    ClientData instanceData,	/* The socket state. */
    char *buf,			/* Where to store data. */
    int toRead,			/* Maximum number of bytes to read. */
    int *errorCodePtr)		/* Where to store error codes. */
{
    SocketInfo *infoPtr = instanceData;
    int bytesRead;
    DWORD error;
    ThreadSpecificData *tsdPtr = TclThreadDataKeyGet(&dataKey);

    *errorCodePtr = 0;

    /*
     * Check that WinSock is initialized; do not call it if not, to prevent
     * system crashes. This can happen at exit time if the exit handler for
     * WinSock ran before other exit handlers that want to use sockets.
     */

    if (!SocketsEnabled()) {
	*errorCodePtr = EFAULT;
	return -1;
    }

    /*
     * First check to see if EOF was already detected, to prevent calling the
     * socket stack after the first time EOF is detected.
     */

    if (infoPtr->flags & SOCKET_EOF) {
	return 0;
    }

    /*
     * Check to see if the socket is connected before trying to read.
     */

    if ((infoPtr->flags & SOCKET_ASYNC_CONNECT)
	    && !WaitForSocketEvent(infoPtr, FD_CONNECT, errorCodePtr)) {
	return -1;
    }

    /*
     * No EOF, and it is connected, so try to read more from the socket. Note
     * that we clear the FD_READ bit because read events are level triggered
     * so a new event will be generated if there is still data available to be
     * read. We have to simulate blocking behavior here since we are always
     * using non-blocking sockets.
     */

    while (1) {
	SendMessage(tsdPtr->hwnd, SOCKET_SELECT,
		(WPARAM) UNSELECT, (LPARAM) infoPtr);
	/* single fd operation: this proc is only called for a connected socket. */
	bytesRead = recv(infoPtr->sockets->fd, buf, toRead, 0);
	infoPtr->readyEvents &= ~(FD_READ);

	/*
	 * Check for end-of-file condition or successful read.
	 */

	if (bytesRead == 0) {
	    infoPtr->flags |= SOCKET_EOF;
	}
	if (bytesRead != SOCKET_ERROR) {
	    break;
	}

	/*
	 * If an error occurs after the FD_CLOSE has arrived, then ignore the
	 * error and report an EOF.
	 */

	if (infoPtr->readyEvents & FD_CLOSE) {
	    infoPtr->flags |= SOCKET_EOF;
	    bytesRead = 0;
	    break;
	}

	error = WSAGetLastError();

	/*
	 * If an RST comes, then ignore the error and report an EOF just like
	 * on unix.
	 */

	if (error == WSAECONNRESET) {
	    infoPtr->flags |= SOCKET_EOF;
	    bytesRead = 0;
	    break;
	}

	/*
	 * Check for error condition or underflow in non-blocking case.
	 */

	if ((infoPtr->flags & SOCKET_ASYNC) || (error != WSAEWOULDBLOCK)) {
	    TclWinConvertError(error);
	    *errorCodePtr = Tcl_GetErrno();
	    bytesRead = -1;
	    break;
	}

	/*
	 * In the blocking case, wait until the file becomes readable or
	 * closed and try again.
	 */

	if (!WaitForSocketEvent(infoPtr, FD_READ|FD_CLOSE, errorCodePtr)) {
	    bytesRead = -1;
	    break;
	}
    }

    SendMessage(tsdPtr->hwnd, SOCKET_SELECT, (WPARAM)SELECT, (LPARAM)infoPtr);

    return bytesRead;
}

/*
 *----------------------------------------------------------------------
 *
 * TcpOutputProc --
 *
 *	This function is called by the generic IO level to write data to a
 *	socket based channel.
 *
 * Results:
 *	The number of bytes written or -1 on failure.
 *
 * Side effects:
 *	Produces output on the socket.
 *
 *----------------------------------------------------------------------
 */

static int
TcpOutputProc(
    ClientData instanceData,	/* The socket state. */
    const char *buf,		/* Where to get data. */
    int toWrite,		/* Maximum number of bytes to write. */
    int *errorCodePtr)		/* Where to store error codes. */
{
    SocketInfo *infoPtr = instanceData;
    int bytesWritten;
    DWORD error;
    ThreadSpecificData *tsdPtr = TclThreadDataKeyGet(&dataKey);

    *errorCodePtr = 0;

    /*
     * Check that WinSock is initialized; do not call it if not, to prevent
     * system crashes. This can happen at exit time if the exit handler for
     * WinSock ran before other exit handlers that want to use sockets.
     */

    if (!SocketsEnabled()) {
	*errorCodePtr = EFAULT;
	return -1;
    }

    /*
     * Check to see if the socket is connected before trying to write.
     */

    if ((infoPtr->flags & SOCKET_ASYNC_CONNECT)
	    && !WaitForSocketEvent(infoPtr, FD_CONNECT, errorCodePtr)) {
	return -1;
    }

    while (1) {
	SendMessage(tsdPtr->hwnd, SOCKET_SELECT,
		(WPARAM) UNSELECT, (LPARAM) infoPtr);

	/* single fd operation: this proc is only called for a connected socket. */
	bytesWritten = send(infoPtr->sockets->fd, buf, toWrite, 0);
	if (bytesWritten != SOCKET_ERROR) {
	    /*
	     * Since Windows won't generate a new write event until we hit an
	     * overflow condition, we need to force the event loop to poll
	     * until the condition changes.
	     */

	    if (infoPtr->watchEvents & FD_WRITE) {
		Tcl_Time blockTime = { 0, 0 };
		Tcl_SetMaxBlockTime(&blockTime);
	    }
	    break;
	}

	/*
	 * Check for error condition or overflow. In the event of overflow, we
	 * need to clear the FD_WRITE flag so we can detect the next writable
	 * event. Note that Windows only sends a new writable event after a
	 * send fails with WSAEWOULDBLOCK.
	 */

	error = WSAGetLastError();
	if (error == WSAEWOULDBLOCK) {
	    infoPtr->readyEvents &= ~(FD_WRITE);
	    if (infoPtr->flags & SOCKET_ASYNC) {
		*errorCodePtr = EWOULDBLOCK;
		bytesWritten = -1;
		break;
	    }
	} else {
	    TclWinConvertError(error);
	    *errorCodePtr = Tcl_GetErrno();
	    bytesWritten = -1;
	    break;
	}

	/*
	 * In the blocking case, wait until the file becomes writable or
	 * closed and try again.
	 */

	if (!WaitForSocketEvent(infoPtr, FD_WRITE|FD_CLOSE, errorCodePtr)) {
	    bytesWritten = -1;
	    break;
	}
    }

    SendMessage(tsdPtr->hwnd, SOCKET_SELECT, (WPARAM)SELECT, (LPARAM)infoPtr);

    return bytesWritten;
}

/*
 *----------------------------------------------------------------------
 *
 * 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(
    ClientData 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. */
{
#ifdef TCL_FEATURE_KEEPALIVE_NAGLE
    SocketInfo *infoPtr = instanceData;
    SOCKET sock;
#endif /*TCL_FEATURE_KEEPALIVE_NAGLE*/

    /*
     * Check that WinSock is initialized; do not call it if not, to prevent
     * system crashes. This can happen at exit time if the exit handler for
     * WinSock ran before other exit handlers that want to use sockets.
     */

    if (!SocketsEnabled()) {
	if (interp) {
	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
		    "winsock is not initialized", -1));
	}
	return TCL_ERROR;
    }

#ifdef TCL_FEATURE_KEEPALIVE_NAGLE
    #error "TCL_FEATURE_KEEPALIVE_NAGLE not reviewed for whether to treat infoPtr->sockets as single fd or list"
    sock = infoPtr->sockets->fd;

    if (!strcasecmp(optionName, "-keepalive")) {
	BOOL val = FALSE;
	int boolVar, rtn;

	if (Tcl_GetBoolean(interp, value, &boolVar) != TCL_OK) {
	    return TCL_ERROR;
	}
	if (boolVar) {
	    val = TRUE;
	}
	rtn = setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
		(const char *) &val, sizeof(BOOL));
	if (rtn != 0) {
	    TclWinConvertError(WSAGetLastError());
	    if (interp) {
		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
			"couldn't set socket option: %s",
			Tcl_PosixError(interp)));
	    }
	    return TCL_ERROR;
	}
	return TCL_OK;
    } else if (!strcasecmp(optionName, "-nagle")) {
	BOOL val = FALSE;
	int boolVar, rtn;

	if (Tcl_GetBoolean(interp, value, &boolVar) != TCL_OK) {
	    return TCL_ERROR;
	}
	if (!boolVar) {
	    val = TRUE;
	}
	rtn = setsockopt(sock, IPPROTO_TCP, TCP_NODELAY,
		(const char *) &val, sizeof(BOOL));
	if (rtn != 0) {
	    TclWinConvertError(WSAGetLastError());
	    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 nagle");
#else
    return Tcl_BadChannelOption(interp, optionName, "");
#endif /*TCL_FEATURE_KEEPALIVE_NAGLE*/
}

/*
 *----------------------------------------------------------------------
 *
 * 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.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
TcpGetOptionProc(
    ClientData 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. */
{
    SocketInfo *infoPtr = instanceData;
    char host[NI_MAXHOST], port[NI_MAXSERV];
    SOCKET sock;
    size_t len = 0;
    int reverseDNS = 0;
#define SUPPRESS_RDNS_VAR "::tcl::unsupported::noReverseDNS"

    /*
     * Check that WinSock is initialized; do not call it if not, to prevent
     * system crashes. This can happen at exit time if the exit handler for
     * WinSock ran before other exit handlers that want to use sockets.
     */

    if (!SocketsEnabled()) {
	if (interp) {
	    Tcl_SetObjResult(interp, Tcl_NewStringObj(
		    "winsock is not initialized", -1));
	}
	return TCL_ERROR;
    }

    sock = infoPtr->sockets->fd;
    if (optionName != NULL) {
	len = strlen(optionName);
    }

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

	optlen = sizeof(int);
	ret = TclWinGetSockOpt(sock, SOL_SOCKET, SO_ERROR,
		(char *)&err, &optlen);
	if (ret == SOCKET_ERROR) {
	    err = WSAGetLastError();
	}
	if (err) {
	    TclWinConvertError(err);
	    Tcl_DStringAppend(dsPtr, Tcl_ErrnoMsg(Tcl_GetErrno()), -1);
	}
	return TCL_OK;
    }

    if (interp != NULL && Tcl_GetVar(interp, SUPPRESS_RDNS_VAR, 0) != NULL) {
	reverseDNS = NI_NUMERICHOST;
    }

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

	if (getpeername(sock, (LPSOCKADDR) &(peername.sa), &size) == 0) {
	    if (len == 0) {
		Tcl_DStringAppendElement(dsPtr, "-peername");
		Tcl_DStringStartSublist(dsPtr);
	    }

	    getnameinfo(&(peername.sa), size, host, sizeof(host),
		    NULL, 0, NI_NUMERICHOST);
	    Tcl_DStringAppendElement(dsPtr, host);
	    getnameinfo(&(peername.sa), size, host, sizeof(host),
		    port, sizeof(port), reverseDNS | NI_NUMERICSERV);
	    Tcl_DStringAppendElement(dsPtr, host);
	    Tcl_DStringAppendElement(dsPtr, port);
	    if (len == 0) {
		Tcl_DStringEndSublist(dsPtr);
	    } else {
		return TCL_OK;
	    }
	} 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 (such sockets have no
	     * peer). {Copied from unix/tclUnixChan.c}
	     */

	    if (len) {
		TclWinConvertError((DWORD) WSAGetLastError());
		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;

	if (len == 0) {
	    Tcl_DStringAppendElement(dsPtr, "-sockname");
	    Tcl_DStringStartSublist(dsPtr);
	}
	for (fds = infoPtr->sockets; fds != NULL; fds = fds->next) {
	    sock = fds->fd;
#ifdef DEBUGGING
	    fprintf(stderr, "sock == %d\n", sock);
#endif
	    size = sizeof(sockname);
	    if (getsockname(sock, &(sockname.sa), &size) >= 0) {
		int flags = reverseDNS;

		found = 1;
		getnameinfo(&sockname.sa, size, host, sizeof(host),
			NULL, 0, NI_NUMERICHOST);
		Tcl_DStringAppendElement(dsPtr, host);

		/*
		 * We don't want to resolve INADDR_ANY and sin6addr_any; they
		 * can sometimes cause problems (and never have a name).
		 */
		flags |= NI_NUMERICSERV;
		if (sockname.sa.sa_family == AF_INET) {
		    if (sockname.sa4.sin_addr.s_addr == INADDR_ANY) {
			flags |= NI_NUMERICHOST;
		    }
		} else if (sockname.sa.sa_family == AF_INET6) {
		    if ((IN6_ARE_ADDR_EQUAL(&sockname.sa6.sin6_addr,
				&in6addr_any)) ||
			    (IN6_IS_ADDR_V4MAPPED(&sockname.sa6.sin6_addr)
			    && sockname.sa6.sin6_addr.s6_addr[12] == 0
			    && sockname.sa6.sin6_addr.s6_addr[13] == 0
			    && sockname.sa6.sin6_addr.s6_addr[14] == 0
			    && sockname.sa6.sin6_addr.s6_addr[15] == 0)) {
			flags |= NI_NUMERICHOST;
		    }
		}
		getnameinfo(&sockname.sa, size, host, sizeof(host),
			port, sizeof(port), flags);
		Tcl_DStringAppendElement(dsPtr, host);
		Tcl_DStringAppendElement(dsPtr, port);
	    }
	}
	if (found) {
	    if (len == 0) {
		Tcl_DStringEndSublist(dsPtr);
	    } else {
		return TCL_OK;
	    }
	} else {
	    if (interp) {
		TclWinConvertError((DWORD) WSAGetLastError());
		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
			"can't get sockname: %s", Tcl_PosixError(interp)));
	    }
	    return TCL_ERROR;
	}
    }

#ifdef TCL_FEATURE_KEEPALIVE_NAGLE
    if (len == 0 || !strncmp(optionName, "-keepalive", len)) {
	int optlen;
	BOOL opt = FALSE;

	if (len == 0) {
	    Tcl_DStringAppendElement(dsPtr, "-keepalive");
	}
	optlen = sizeof(BOOL);
	getsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (char *)&opt, &optlen);
	if (opt) {
	    Tcl_DStringAppendElement(dsPtr, "1");
	} else {
	    Tcl_DStringAppendElement(dsPtr, "0");
	}
	if (len > 0) {
	    return TCL_OK;
	}
    }

    if (len == 0 || !strncmp(optionName, "-nagle", len)) {
	int optlen;
	BOOL opt = FALSE;

	if (len == 0) {
	    Tcl_DStringAppendElement(dsPtr, "-nagle");
	}
	optlen = sizeof(BOOL);
	getsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (char *)&opt, &optlen);
	if (opt) {
	    Tcl_DStringAppendElement(dsPtr, "0");
	} else {
	    Tcl_DStringAppendElement(dsPtr, "1");
	}
	if (len > 0) {
	    return TCL_OK;
	}
    }
#endif /*TCL_FEATURE_KEEPALIVE_NAGLE*/

    if (len > 0) {
#ifdef TCL_FEATURE_KEEPALIVE_NAGLE
	return Tcl_BadChannelOption(interp, optionName,
		"peername sockname keepalive nagle");
#else
	return Tcl_BadChannelOption(interp, optionName, "peername sockname");
#endif /*TCL_FEATURE_KEEPALIVE_NAGLE*/
    }

    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * TcpWatchProc --
 *
 *	Informs the channel driver of the events that the generic channel code
 *	wishes to receive on this socket.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	May cause the notifier to poll if any of the specified conditions are
 *	already true.
 *
 *----------------------------------------------------------------------
 */

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

    DEBUG((mask & TCL_READABLE) ? "+r":"-r");
    DEBUG((mask & TCL_WRITABLE) ? "+w":"-w");

    /*
     * Update the watch events mask. Only if the socket is not a server
     * socket. [Bug 557878]
     */

    if (!infoPtr->acceptProc) {
	infoPtr->watchEvents = 0;
	if (mask & TCL_READABLE) {
	    infoPtr->watchEvents |= (FD_READ|FD_CLOSE);
	}
	if (mask & TCL_WRITABLE) {
	    infoPtr->watchEvents |= (FD_WRITE|FD_CLOSE);
	}

	/*
	 * If there are any conditions already set, then tell the notifier to
	 * poll rather than block.
	 */

	if (infoPtr->readyEvents & infoPtr->watchEvents) {
	    Tcl_Time blockTime = { 0, 0 };

	    Tcl_SetMaxBlockTime(&blockTime);
	}
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TcpGetProc --
 *
 *	Called from Tcl_GetChannelHandle to retrieve an OS handle from inside
 *	a TCP socket based channel.
 *
 * Results:
 *	Returns TCL_OK with the socket in handlePtr.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
TcpGetHandleProc(
    ClientData instanceData,	/* The socket state. */
    int direction,		/* Not used. */
    ClientData *handlePtr)	/* Where to store the handle. */
{
    SocketInfo *statePtr = instanceData;

    *handlePtr = INT2PTR(statePtr->sockets->fd);
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * SocketThread --
 *
 *	Helper thread used to manage the socket event handling window.
 *
 * Results:
 *	1 if unable to create socket event window, 0 otherwise.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static DWORD WINAPI
SocketThread(
    LPVOID arg)
{
    MSG msg;
    ThreadSpecificData *tsdPtr = arg;

    /*
     * Create a dummy window receiving socket events.
     */

    tsdPtr->hwnd = CreateWindow(classname, classname, WS_TILED, 0, 0, 0, 0,
	    NULL, NULL, windowClass.hInstance, arg);

    /*
     * Signalize thread creator that we are done creating the window.
     */

    SetEvent(tsdPtr->readyEvent);

    /*
     * If unable to create the window, exit this thread immediately.
     */

    if (tsdPtr->hwnd == NULL) {
	return 1;
    }

    /*
     * Process all messages on the socket window until WM_QUIT. This threads
     * exits only when instructed to do so by the call to
     * PostMessage(SOCKET_TERMINATE) in TclpFinalizeSockets().
     */

    while (GetMessage(&msg, NULL, 0, 0) > 0) {
	DispatchMessage(&msg);
    }

    /*
     * This releases waiters on thread exit in TclpFinalizeSockets()
     */

    SetEvent(tsdPtr->readyEvent);

    return msg.wParam;
}


/*
 *----------------------------------------------------------------------
 *
 * SocketProc --
 *
 *	This function is called when WSAAsyncSelect has been used to register
 *	interest in a socket event, and the event has occurred.
 *
 * Results:
 *	0 on success.
 *
 * Side effects:
 *	The flags for the given socket are updated to reflect the event that
 *	occured.
 *
 *----------------------------------------------------------------------
 */

static LRESULT CALLBACK
SocketProc(
    HWND hwnd,
    UINT message,
    WPARAM wParam,
    LPARAM lParam)
{
    int event, error;
    SOCKET socket;
    SocketInfo *infoPtr = NULL; /* DEBUG */
    TcpFdList *fds = NULL;
    ThreadSpecificData *tsdPtr = (ThreadSpecificData *)
#ifdef _WIN64
	    GetWindowLongPtr(hwnd, GWLP_USERDATA);
#else
	    GetWindowLong(hwnd, GWL_USERDATA);
#endif

    switch (message) {
    default:
	return DefWindowProc(hwnd, message, wParam, lParam);
	break;

    case WM_CREATE:
	/*
	 * Store the initial tsdPtr, it's from a different thread, so it's not
	 * directly accessible, but needed.
	 */

#ifdef _WIN64
	SetWindowLongPtr(hwnd, GWLP_USERDATA,
		(LONG_PTR) ((LPCREATESTRUCT)lParam)->lpCreateParams);
#else
	SetWindowLong(hwnd, GWL_USERDATA,
		(LONG) ((LPCREATESTRUCT)lParam)->lpCreateParams);
#endif
	break;

    case WM_DESTROY:
	PostQuitMessage(0);
	break;

    case SOCKET_MESSAGE:
	event = WSAGETSELECTEVENT(lParam);
	error = WSAGETSELECTERROR(lParam);
	socket = (SOCKET) wParam;

	/*
	 * Find the specified socket on the socket list and update its
	 * eventState flag.
	 */

	DEBUG("FOO");
	WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
	DEBUG("BAR");
	for (infoPtr = tsdPtr->socketList; infoPtr != NULL;
		infoPtr = infoPtr->nextPtr) {
	    for (fds = infoPtr->sockets; fds != NULL; fds = fds->next) {
#ifdef DEBUGGING
		fprintf(stderr,"socket = %d, fd=%d, event = %d, error = %d\n",
			socket, fds->fd, event, error);
#endif
		if (fds->fd == socket) {
		    if (event & FD_READ) 
			DEBUG("|->FD_READ");
		    if (event & FD_WRITE) 
			DEBUG("|->FD_WRITE");

		    /*
		     * Update the socket state.
		     *
		     * A count of FD_ACCEPTS is stored, so if an FD_CLOSE event
		     * happens, then clear the FD_ACCEPT count. Otherwise,
		     * increment the count if the current event is an FD_ACCEPT.
		     */

		    if (event & FD_CLOSE) {
			DEBUG("FD_CLOSE");
			infoPtr->acceptEventCount = 0;
			infoPtr->readyEvents &= ~(FD_WRITE|FD_ACCEPT);
		    } else if (event & FD_ACCEPT) {
			DEBUG("FD_ACCEPT");
			    infoPtr->acceptEventCount++;
		    }

		    if (event & FD_CONNECT) {
			DEBUG("FD_CONNECT");
			/*
			 * The socket is now connected, clear the async connect
			 * flag.
			 */

			//infoPtr->flags &= ~(SOCKET_ASYNC_CONNECT);

			/*
			 * Remember any error that occurred so we can report
			 * connection failures.
			 */
			if (error != ERROR_SUCCESS) {
			    TclWinConvertError((DWORD) error);
			    infoPtr->lastError = Tcl_GetErrno();
			}
		    }
#if 0
		    if (infoPtr->flags & SOCKET_ASYNC_CONNECT) {
			DEBUG("SOCKET_ASYNC_CONNECT");
			// infoPtr->flags &= ~(SOCKET_ASYNC_CONNECT);
			if (error != ERROR_SUCCESS) {
			    TclWinConvertError((DWORD) error);
			    infoPtr->lastError = Tcl_GetErrno();
			}
			infoPtr->readyEvents |= FD_WRITE;
		    }
#endif
		    infoPtr->readyEvents |= event;

		    /*
		     * Wake up the Main Thread.
		     */

		    SetEvent(tsdPtr->readyEvent);
		    Tcl_ThreadAlert(tsdPtr->threadId);
		    break;
		}
	    }
	}
	SetEvent(tsdPtr->socketListLock);
	break;

    case SOCKET_SELECT:
	    DEBUG("SOCKET_SELECT");
	infoPtr = (SocketInfo *) lParam;
	for (fds = infoPtr->sockets; fds != NULL; fds = fds->next) {
	    infoPtr = (SocketInfo *) lParam;
	    if (wParam == SELECT) {
		DEBUG("SELECT");
		if (infoPtr->selectEvents & FD_READ) DEBUG("  READ");
		if (infoPtr->selectEvents & FD_WRITE) DEBUG("  WRITE");
		if (infoPtr->selectEvents & FD_CLOSE) DEBUG("  CLOSE");
		if (infoPtr->selectEvents & FD_CONNECT) DEBUG("  CONNECT");
		if (infoPtr->selectEvents & FD_ACCEPT) DEBUG("  ACCEPT");
		WSAAsyncSelect(fds->fd, hwnd,
			SOCKET_MESSAGE, infoPtr->selectEvents);
	    } else {
		/*
		 * Clear the selection mask
		 */

		DEBUG("!SELECT");
		WSAAsyncSelect(fds->fd, hwnd, 0, 0);
	    }
	}
	break;

    case SOCKET_TERMINATE:
	    DEBUG("SOCKET_TERMINATE");
	DestroyWindow(hwnd);
	break;
    }

    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_GetHostName --
 *
 *	Returns the name of the local host.
 *
 * Results:
 *	A string containing the network name for this machine. The caller must
 *	not modify or free this string.
 *
 * Side effects:
 *	Caches the name to return for future calls.
 *
 *----------------------------------------------------------------------
 */

const char *
Tcl_GetHostName(void)
{
    return Tcl_GetString(TclGetProcessGlobalValue(&hostName));
}

/*
 *----------------------------------------------------------------------
 *
 * InitializeHostName --
 *
 *	This routine sets the process global value of the name of the local
 *	host on which the process is running.
 *
 * Results:
 *	None.
 *
 *----------------------------------------------------------------------
 */

void
InitializeHostName(
    char **valuePtr,
    int *lengthPtr,
    Tcl_Encoding *encodingPtr)
{
    TCHAR tbuf[MAX_COMPUTERNAME_LENGTH + 1];
    DWORD length = MAX_COMPUTERNAME_LENGTH + 1;
    Tcl_DString ds;

    if (GetComputerName(tbuf, &length) != 0) {
	/*
	 * Convert string from native to UTF then change to lowercase.
	 */

	Tcl_UtfToLower(Tcl_WinTCharToUtf(tbuf, -1, &ds));

    } else {
	Tcl_DStringInit(&ds);
	if (TclpHasSockets(NULL) == TCL_OK) {
	    /*
	     * The buffer size of 256 is recommended by the MSDN page that
	     * documents gethostname() as being always adequate.
	     */

	    Tcl_DString inDs;

	    Tcl_DStringInit(&inDs);
	    Tcl_DStringSetLength(&inDs, 256);
	    if (gethostname(Tcl_DStringValue(&inDs),
		    Tcl_DStringLength(&inDs)) == 0) {
		Tcl_ExternalToUtfDString(NULL, Tcl_DStringValue(&inDs), -1,
			&ds);
	    }
	    Tcl_DStringFree(&inDs);
	}
    }

    *encodingPtr = Tcl_GetEncoding(NULL, "utf-8");
    *lengthPtr = Tcl_DStringLength(&ds);
    *valuePtr = ckalloc((*lengthPtr) + 1);
    memcpy(*valuePtr, Tcl_DStringValue(&ds), (size_t)(*lengthPtr)+1);
    Tcl_DStringFree(&ds);
}

/*
 *----------------------------------------------------------------------
 *
 * TclWinGetSockOpt, et al. --
 *
 *	These functions are wrappers that let us bind the WinSock API
 *	dynamically so we can run on systems that don't have the wsock32.dll.
 *	We need wrappers for these interfaces because they are called from the
 *	generic Tcl code.
 *
 * Results:
 *	As defined for each function.
 *
 * Side effects:
 *	As defined for each function.
 *
 *----------------------------------------------------------------------
 */

int
TclWinGetSockOpt(
    SOCKET s,
    int level,
    int optname,
    char *optval,
    int *optlen)
{
    /*
     * Check that WinSock is initialized; do not call it if not, to prevent
     * system crashes. This can happen at exit time if the exit handler for
     * WinSock ran before other exit handlers that want to use sockets.
     */

    if (!SocketsEnabled()) {
	return SOCKET_ERROR;
    }

    return getsockopt(s, level, optname, optval, optlen);
}

int
TclWinSetSockOpt(
    SOCKET s,
    int level,
    int optname,
    const char *optval,
    int optlen)
{
    /*
     * Check that WinSock is initialized; do not call it if not, to prevent
     * system crashes. This can happen at exit time if the exit handler for
     * WinSock ran before other exit handlers that want to use sockets.
     */

    if (!SocketsEnabled()) {
	return SOCKET_ERROR;
    }

    return setsockopt(s, level, optname, optval, optlen);
}

#undef TclpInetNtoa
char *
TclpInetNtoa(
    struct in_addr addr)
{
    /*
     * Check that WinSock is initialized; do not call it if not, to prevent
     * system crashes. This can happen at exit time if the exit handler for
     * WinSock ran before other exit handlers that want to use sockets.
     */

    if (!SocketsEnabled()) {
        return NULL;
    }

    return inet_ntoa(addr);
}

struct servent *
TclWinGetServByName(
    const char *name,
    const char *proto)
{
    /*
     * Check that WinSock is initialized; do not call it if not, to prevent
     * system crashes. This can happen at exit time if the exit handler for
     * WinSock ran before other exit handlers that want to use sockets.
     */

    if (!SocketsEnabled()) {
	return NULL;
    }

    return getservbyname(name, proto);
}

/*
 *----------------------------------------------------------------------
 *
 * TcpThreadActionProc --
 *
 *	Insert or remove any thread local refs to this channel.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Changes thread local list of valid channels.
 *
 *----------------------------------------------------------------------
 */

static void
TcpThreadActionProc(
    ClientData instanceData,
    int action)
{
    ThreadSpecificData *tsdPtr;
    SocketInfo *infoPtr = instanceData;
    int notifyCmd;

    if (action == TCL_CHANNEL_THREAD_INSERT) {
	/*
	 * Ensure that socket subsystem is initialized in this thread, or else
	 * sockets will not work.
	 */

	Tcl_MutexLock(&socketMutex);
	InitSockets();
	Tcl_MutexUnlock(&socketMutex);

	tsdPtr = TCL_TSD_INIT(&dataKey);

	WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
	infoPtr->nextPtr = tsdPtr->socketList;
	tsdPtr->socketList = infoPtr;
	SetEvent(tsdPtr->socketListLock);

	notifyCmd = SELECT;
    } else {
	SocketInfo **nextPtrPtr;
	int removed = 0;

	tsdPtr = TCL_TSD_INIT(&dataKey);

	/*
	 * TIP #218, Bugfix: All access to socketList has to be protected by
	 * the lock.
	 */

	WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
	for (nextPtrPtr = &(tsdPtr->socketList); (*nextPtrPtr) != NULL;
		nextPtrPtr = &((*nextPtrPtr)->nextPtr)) {
	    if ((*nextPtrPtr) == infoPtr) {
		(*nextPtrPtr) = infoPtr->nextPtr;
		removed = 1;
		break;
	    }
	}
	SetEvent(tsdPtr->socketListLock);

	/*
	 * This could happen if the channel was created in one thread and then
	 * moved to another without updating the thread local data in each
	 * thread.
	 */

	if (!removed) {
	    Tcl_Panic("file info ptr not on thread channel list");
	}

	notifyCmd = UNSELECT;
    }

    /*
     * Ensure that, or stop, notifications for the socket occur in this
     * thread.
     */

    SendMessage(tsdPtr->hwnd, SOCKET_SELECT,
	    (WPARAM) notifyCmd, (LPARAM) infoPtr);
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */