summaryrefslogtreecommitdiff
path: root/ext/socket/socket.c
blob: 08276bf8b63f4a4727af1ecc28f09bd9b757c52a (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
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
/************************************************

  socket.c -

  $Author$
  created at: Thu Mar 31 12:21:29 JST 1994

  Copyright (C) 1993-2007 Yukihiro Matsumoto

************************************************/

#include "ruby/ruby.h"
#include "ruby/io.h"
#include "ruby/util.h"
#include <stdio.h>
#include <sys/types.h>

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_SYS_UIO_H
#include <sys/uio.h>
#endif

#ifdef HAVE_XTI_H
#include <xti.h>
#endif

#ifndef _WIN32
#if defined(__BEOS__) && !defined(__HAIKU__) && !defined(BONE)
# include <net/socket.h>
#else
# include <sys/socket.h>
#endif
#include <netinet/in.h>
#ifdef HAVE_NETINET_IN_SYSTM_H
# include <netinet/in_systm.h>
#endif
#ifdef HAVE_NETINET_TCP_H
# include <netinet/tcp.h>
#endif
#ifdef HAVE_NETINET_UDP_H
# include <netinet/udp.h>
#endif
#ifdef HAVE_ARPA_INET_H
# include <arpa/inet.h>
#endif
#include <netdb.h>
#endif
#include <errno.h>
#ifdef HAVE_SYS_UN_H
#include <sys/un.h>
#endif

#if defined(HAVE_FCNTL)
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif
#endif
#ifndef EWOULDBLOCK
#define EWOULDBLOCK EAGAIN
#endif
#ifndef HAVE_GETADDRINFO
# include "addrinfo.h"
#endif
#include "sockport.h"

static int do_not_reverse_lookup = 0;
#define FMODE_NOREVLOOKUP 0x100

VALUE rb_cBasicSocket;
VALUE rb_cIPSocket;
VALUE rb_cTCPSocket;
VALUE rb_cTCPServer;
VALUE rb_cUDPSocket;
#ifdef AF_UNIX
VALUE rb_cUNIXSocket;
VALUE rb_cUNIXServer;
#endif
VALUE rb_cSocket;
static VALUE rb_cAddrInfo;

static VALUE rb_eSocket;

#ifdef SOCKS
VALUE rb_cSOCKSSocket;
#ifdef SOCKS5
#include <socks.h>
#else
void SOCKSinit();
int Rconnect();
#endif
#endif

#define BLOCKING_REGION(func, arg) (long)rb_thread_blocking_region((func), (arg), RUBY_UBF_IO, 0)

#define INET_CLIENT 0
#define INET_SERVER 1
#define INET_SOCKS  2

#ifndef HAVE_SOCKADDR_STORAGE
/*
 * RFC 2553: protocol-independent placeholder for socket addresses
 */
#define _SS_MAXSIZE	128
#define _SS_ALIGNSIZE	(sizeof(double))
#define _SS_PAD1SIZE	(_SS_ALIGNSIZE - sizeof(unsigned char) * 2)
#define _SS_PAD2SIZE	(_SS_MAXSIZE - sizeof(unsigned char) * 2 - \
				_SS_PAD1SIZE - _SS_ALIGNSIZE)

struct sockaddr_storage {
#ifdef HAVE_SA_LEN
	unsigned char ss_len;		/* address length */
	unsigned char ss_family;	/* address family */
#else
	unsigned short ss_family;
#endif
	char	__ss_pad1[_SS_PAD1SIZE];
	double	__ss_align;	/* force desired structure storage alignment */
	char	__ss_pad2[_SS_PAD2SIZE];
};
#endif

static void sock_define_const(const char *name, int value, VALUE mConst);
static void sock_define_uconst(const char *name, unsigned int value, VALUE mConst);
#define sock_define_const(name, value) sock_define_const(name, value, mConst)
#define sock_define_uconst(name, value) sock_define_uconst(name, value, mConst)
#include "constants.h"
#undef sock_define_const
#undef sock_define_uconst

#if defined(INET6) && (defined(LOOKUP_ORDER_HACK_INET) || defined(LOOKUP_ORDER_HACK_INET6))
#define LOOKUP_ORDERS (sizeof(lookup_order_table) / sizeof(lookup_order_table[0]))
static const int lookup_order_table[] = {
#if defined(LOOKUP_ORDER_HACK_INET)
    PF_INET, PF_INET6, PF_UNSPEC,
#elif defined(LOOKUP_ORDER_HACK_INET6)
    PF_INET6, PF_INET, PF_UNSPEC,
#else
    /* should not happen */
#endif
};

static int
ruby_getaddrinfo(const char *nodename, const char *servname,
		 const struct addrinfo *hints, struct addrinfo **res)
{
    struct addrinfo tmp_hints;
    int i, af, error;

    if (hints->ai_family != PF_UNSPEC) {
	return getaddrinfo(nodename, servname, hints, res);
    }

    for (i = 0; i < LOOKUP_ORDERS; i++) {
	af = lookup_order_table[i];
	MEMCPY(&tmp_hints, hints, struct addrinfo, 1);
	tmp_hints.ai_family = af;
	error = getaddrinfo(nodename, servname, &tmp_hints, res);
	if (error) {
	    if (tmp_hints.ai_family == PF_UNSPEC) {
		break;
	    }
	}
	else {
	    break;
	}
    }

    return error;
}
#define getaddrinfo(node,serv,hints,res) ruby_getaddrinfo((node),(serv),(hints),(res))
#endif

#if defined(_AIX)
static int
ruby_getaddrinfo__aix(const char *nodename, const char *servname,
		      struct addrinfo *hints, struct addrinfo **res)
{
    int error = getaddrinfo(nodename, servname, hints, res);
    struct addrinfo *r;
    if (error)
	return error;
    for (r = *res; r != NULL; r = r->ai_next) {
	if (r->ai_addr->sa_family == 0)
	    r->ai_addr->sa_family = r->ai_family;
	if (r->ai_addr->sa_len == 0)
	    r->ai_addr->sa_len = r->ai_addrlen;
    }
    return 0;
}
#undef getaddrinfo
#define getaddrinfo(node,serv,hints,res) ruby_getaddrinfo__aix((node),(serv),(hints),(res))
static int
ruby_getnameinfo__aix(const struct sockaddr *sa, size_t salen,
		      char *host, size_t hostlen,
		      char *serv, size_t servlen, int flags)
{
    struct sockaddr_in6 *sa6;
    u_int32_t *a6;

    if (sa->sa_family == AF_INET6) {
	sa6 = (struct sockaddr_in6 *)sa;
	a6 = sa6->sin6_addr.u6_addr.u6_addr32;

	if (a6[0] == 0 && a6[1] == 0 && a6[2] == 0 && a6[3] == 0) {
	    strncpy(host, "::", hostlen);
	    snprintf(serv, servlen, "%d", sa6->sin6_port);
	    return 0;
	}
    }
    return getnameinfo(sa, salen, host, hostlen, serv, servlen, flags);
}
#undef getnameinfo
#define getnameinfo(sa, salen, host, hostlen, serv, servlen, flags) \
            ruby_getnameinfo__aix((sa), (salen), (host), (hostlen), (serv), (servlen), (flags))

#ifndef CMSG_SPACE
# define CMSG_SPACE(len) (_CMSG_ALIGN(sizeof(struct cmsghdr)) + _CMSG_ALIGN(len))
#endif
#ifndef CMSG_LEN
# define CMSG_LEN(len) (_CMSG_ALIGN(sizeof(struct cmsghdr)) + (len))
#endif
#endif

#ifdef __BEOS__
#undef close
#define close closesocket
#endif

struct getaddrinfo_arg
{
    const char *node;
    const char *service;
    const struct addrinfo *hints;
    struct addrinfo **res;
};

static VALUE
nogvl_getaddrinfo(void *arg)
{
    struct getaddrinfo_arg *ptr = arg;
    return getaddrinfo(ptr->node, ptr->service,
                       ptr->hints, ptr->res);
}

static int
rb_getaddrinfo(const char *node, const char *service,
               const struct addrinfo *hints,
               struct addrinfo **res)
{
    struct getaddrinfo_arg arg;
    int ret;
    arg.node = node;
    arg.service = service;
    arg.hints = hints;
    arg.res = res;
    ret = BLOCKING_REGION(nogvl_getaddrinfo, &arg);
    return ret;
}

struct getnameinfo_arg
{
    const struct sockaddr *sa;
    socklen_t salen;
    char *host;
    size_t hostlen;
    char *serv;
    size_t servlen;
    int flags;
};

static VALUE
nogvl_getnameinfo(void *arg)
{
    struct getnameinfo_arg *ptr = arg;
    return getnameinfo(ptr->sa, ptr->salen,
                       ptr->host, ptr->hostlen,
                       ptr->serv, ptr->servlen,
                       ptr->flags);
}

static int
rb_getnameinfo(const struct sockaddr *sa, socklen_t salen,
           char *host, size_t hostlen,
           char *serv, size_t servlen, int flags)
{
    struct getnameinfo_arg arg;
    int ret;
    arg.sa = sa;
    arg.salen = salen;
    arg.host = host;
    arg.hostlen = hostlen;
    arg.serv = serv;
    arg.servlen = servlen;
    arg.flags = flags;
    ret = BLOCKING_REGION(nogvl_getnameinfo, &arg);
    return ret;
}

static int
constant_arg(VALUE arg, int (*str_to_int)(char*, int, int*), const char *errmsg)
{
    VALUE tmp;
    char *ptr;
    int ret;

    if (SYMBOL_P(arg)) {
        arg = rb_sym_to_s(arg);
        goto str;
    }
    else if (!NIL_P(tmp = rb_check_string_type(arg))) {
	arg = tmp;
      str:
	rb_check_safe_obj(arg);
        ptr = RSTRING_PTR(arg);
        if (str_to_int(ptr, RSTRING_LEN(arg), &ret) == -1)
	    rb_raise(rb_eSocket, "%s: %s", errmsg, ptr);
    }
    else {
	ret = NUM2INT(arg);
    }
    return ret;
}

static int
family_arg(VALUE domain)
{
    /* convert AF_INET, etc. */
    return constant_arg(domain, family_to_int, "unknown socket domain");
}

static int
socktype_arg(VALUE type)
{
    /* convert SOCK_STREAM, etc. */
    return constant_arg(type, socktype_to_int, "unknown socket type");
}

static int
level_arg(VALUE level)
{
    /* convert SOL_SOCKET, IPPROTO_TCP, etc. */
    return constant_arg(level, level_to_int, "unknown protocol level");
}

static int
optname_arg(int level, VALUE optname)
{
    switch (level) {
      case SOL_SOCKET:
        return constant_arg(optname, so_optname_to_int, "unknown socket level option name");
      case IPPROTO_IP:
        return constant_arg(optname, ip_optname_to_int, "unknown IP level option name");
#ifdef IPPROTO_IPV6
      case IPPROTO_IPV6:
        return constant_arg(optname, ipv6_optname_to_int, "unknown IPv6 level option name");
#endif
      case IPPROTO_TCP:
        return constant_arg(optname, tcp_optname_to_int, "unknown TCP level option name");
      case IPPROTO_UDP:
        return constant_arg(optname, udp_optname_to_int, "unknown UDP level option name");
      default:
        return NUM2INT(optname);
    }
}

static int
shutdown_how_arg(VALUE how)
{
    /* convert SHUT_RD, SHUT_WR, SHUT_RDWR. */
    return constant_arg(how, shutdown_how_to_int, "unknown shutdown argument");
}

static VALUE
init_sock(VALUE sock, int fd)
{
    rb_io_t *fp;

    MakeOpenFile(sock, fp);
    fp->fd = fd;
    fp->mode = FMODE_READWRITE|FMODE_DUPLEX;
    rb_io_ascii8bit_binmode(sock);
    if (do_not_reverse_lookup) {
	fp->mode |= FMODE_NOREVLOOKUP;
    }
    rb_io_synchronized(fp);

    return sock;
}

/*
 * call-seq:
 *   BasicSocket.for_fd(fd) => basicsocket
 *
 * Returns a socket object which contains the file descriptor, _fd_.
 *
 *   # If invoked by inetd, STDIN/STDOUT/STDERR is a socket.
 *   STDIN_SOCK = Socket.for_fd(STDIN.fileno)
 *   p STDIN_SOCK.remote_address
 *
 */
static VALUE
bsock_s_for_fd(VALUE klass, VALUE fd)
{
    rb_io_t *fptr;
    VALUE sock = init_sock(rb_obj_alloc(klass), NUM2INT(fd));

    GetOpenFile(sock, fptr);

    return sock;
}

/*
 * call-seq:
 *   basicsocket.shutdown([how]) => 0
 *
 * Calls shutdown(2) system call.
 *
 * s.shutdown(Socket::SHUT_RD) disallows further read.
 *
 * s.shutdown(Socket::SHUT_WR) disallows further write.
 *
 * s.shutdown(Socket::SHUT_RDWR) disallows further read and write.
 *
 * _how_ can be symbol or string:
 * - :RD, :SHUT_RD, "RD" and "SHUT_RD" are accepted as Socket::SHUT_RD.
 * - :WR, :SHUT_WR, "WR" and "SHUT_WR" are accepted as Socket::SHUT_WR.
 * - :RDWR, :SHUT_RDWR, "RDWR" and "SHUT_RDWR" are accepted as Socket::SHUT_RDWR.
 *
 *   UNIXSocket.pair {|s1, s2|
 *     s1.puts "ping"
 *     s1.shutdown(:WR)
 *     p s2.read          #=> "ping\n"
 *     s2.puts "pong"
 *     s2.close
 *     p s1.read          #=> "pong\n"
 *   }
 *   
 */
static VALUE
bsock_shutdown(int argc, VALUE *argv, VALUE sock)
{
    VALUE howto;
    int how;
    rb_io_t *fptr;

    if (rb_safe_level() >= 4 && !OBJ_TAINTED(sock)) {
	rb_raise(rb_eSecurityError, "Insecure: can't shutdown socket");
    }
    rb_scan_args(argc, argv, "01", &howto);
    if (howto == Qnil)
	how = SHUT_RDWR;
    else {
	how = shutdown_how_arg(howto);
        if (how != SHUT_WR && how != SHUT_RD && how != SHUT_RDWR) {
	    rb_raise(rb_eArgError, "`how' should be either :SHUT_RD, :SHUT_WR, :SHUT_RDWR");
	}
    }
    GetOpenFile(sock, fptr);
    if (shutdown(fptr->fd, how) == -1)
	rb_sys_fail(0);

    return INT2FIX(0);
}

/*
 * call-seq:
 *   basicsocket.close_read => nil
 *
 * Disallows further read.
 *
 *   s1, s2 = UNIXSocket.pair
 *   s1.close_read
 *   s2.puts #=> Broken pipe (Errno::EPIPE)
 */
static VALUE
bsock_close_read(VALUE sock)
{
    rb_io_t *fptr;

    if (rb_safe_level() >= 4 && !OBJ_TAINTED(sock)) {
	rb_raise(rb_eSecurityError, "Insecure: can't close socket");
    }
    GetOpenFile(sock, fptr);
    shutdown(fptr->fd, 0);
    if (!(fptr->mode & FMODE_WRITABLE)) {
	return rb_io_close(sock);
    }
    fptr->mode &= ~FMODE_READABLE;

    return Qnil;
}

/*
 * call-seq:
 *   basicsocket.close_write => nil
 *
 * Disallows further write.
 *
 *   UNIXSocket.pair {|s1, s2|
 *     s1.print "ping"
 *     s1.close_write
 *     p s2.read        #=> "ping"
 *     s2.print "pong"
 *     s2.close
 *     p s1.read        #=> "pong"
 *   }
 */
static VALUE
bsock_close_write(VALUE sock)
{
    rb_io_t *fptr;

    if (rb_safe_level() >= 4 && !OBJ_TAINTED(sock)) {
	rb_raise(rb_eSecurityError, "Insecure: can't close socket");
    }
    GetOpenFile(sock, fptr);
    if (!(fptr->mode & FMODE_READABLE)) {
	return rb_io_close(sock);
    }
    shutdown(fptr->fd, 1);
    fptr->mode &= ~FMODE_WRITABLE;

    return Qnil;
}

/*
 * Document-method: setsockopt
 * call-seq: setsockopt(level, optname, optval)
 *
 * Sets a socket option. These are protocol and system specific, see your
 * local sytem documentation for details.
 *
 * === Parameters
 * * +level+ is an integer, usually one of the SOL_ constants such as
 *   Socket::SOL_SOCKET, or a protocol level.
 * * +optname+ is an integer, usually one of the SO_ constants, such
 *   as Socket::SO_REUSEADDR.
 * * +optval+ is the value of the option, it is passed to the underlying
 *   setsockopt() as a pointer to a certain number of bytes. How this is
 *   done depends on the type:
 *   - Fixnum: value is assigned to an int, and a pointer to the int is
 *     passed, with length of sizeof(int).
 *   - true or false: 1 or 0 (respectively) is assigned to an int, and the
 *     int is passed as for a Fixnum. Note that +false+ must be passed,
 *     not +nil+.
 *   - String: the string's data and length is passed to the socket.
 *
 * === Examples
 *
 * Some socket options are integers with boolean values, in this case
 * #setsockopt could be called like this:
 *   sock.setsockopt(Socket::SOL_SOCKET,Socket::SO_REUSEADDR, true)
 *
 * Some socket options are integers with numeric values, in this case
 * #setsockopt could be called like this:
 *   sock.setsockopt(Socket::IPPROTO_IP, Socket::IP_TTL, 255)
 *
 * Option values may be structs. Passing them can be complex as it involves
 * examining your system headers to determine the correct definition. An
 * example is an +ip_mreq+, which may be defined in your system headers as:
 *   struct ip_mreq {
 *     struct  in_addr imr_multiaddr;
 *     struct  in_addr imr_interface;
 *   };
 * 
 * In this case #setsockopt could be called like this:
 *   optval =  IPAddr.new("224.0.0.251") + Socket::INADDR_ANY
 *   sock.setsockopt(Socket::IPPROTO_IP, Socket::IP_ADD_MEMBERSHIP, optval)
 *
*/
static VALUE
bsock_setsockopt(VALUE sock, VALUE lev, VALUE optname, VALUE val)
{
    int level, option;
    rb_io_t *fptr;
    int i;
    char *v;
    int vlen;

    rb_secure(2);
    level = level_arg(lev);
    option = optname_arg(level, optname);

    switch (TYPE(val)) {
      case T_FIXNUM:
	i = FIX2INT(val);
	goto numval;
      case T_FALSE:
	i = 0;
	goto numval;
      case T_TRUE:
	i = 1;
      numval:
	v = (char*)&i; vlen = sizeof(i);
	break;
      default:
	StringValue(val);
	v = RSTRING_PTR(val);
	vlen = RSTRING_LEN(val);
	break;
    }

#define rb_sys_fail_path(path) rb_sys_fail(NIL_P(path) ? 0 : RSTRING_PTR(path))

    GetOpenFile(sock, fptr);
    if (setsockopt(fptr->fd, level, option, v, vlen) < 0)
	rb_sys_fail_path(fptr->pathv);

    return INT2FIX(0);
}

/*
 * Document-method: getsockopt
 * call-seq: getsockopt(level, optname)
 *
 * Gets a socket option. These are protocol and system specific, see your
 * local sytem documentation for details. The option is returned as
 * a String with the data being the binary value of the socket option.
 *
 * === Parameters
 * * +level+ is an integer, usually one of the SOL_ constants such as
 *   Socket::SOL_SOCKET, or a protocol level.
 * * +optname+ is an integer, usually one of the SO_ constants, such
 *   as Socket::SO_REUSEADDR.
 *
 * === Examples
 *
 * Some socket options are integers with boolean values, in this case
 * #getsockopt could be called like this:
 *   optval = sock.getsockopt(Socket::SOL_SOCKET,Socket::SO_REUSEADDR)
 *   optval = optval.unpack "i"
 *   reuseaddr = optval[0] == 0 ? false : true
 *
 * Some socket options are integers with numeric values, in this case
 * #getsockopt could be called like this:
 *   optval = sock.getsockopt(Socket::IPPROTO_IP, Socket::IP_TTL)
 *   ipttl = optval.unpack("i")[0]
 *
 * Option values may be structs. Decoding them can be complex as it involves
 * examining your system headers to determine the correct definition. An
 * example is a +struct linger+, which may be defined in your system headers
 * as:
 *   struct linger {
 *     int l_onoff;
 *     int l_linger;
 *   };
 * 
 * In this case #getsockopt could be called like this:
 *   optval =  sock.getsockopt(Socket::SOL_SOCKET, Socket::SO_LINGER)
 *   onoff, linger = optval.unpack "ii"
*/
static VALUE
bsock_getsockopt(VALUE sock, VALUE lev, VALUE optname)
{
#if !defined(__BEOS__)
    int level, option;
    socklen_t len;
    char *buf;
    rb_io_t *fptr;

    level = level_arg(lev);
    option = optname_arg(level, optname);
    len = 256;
    buf = ALLOCA_N(char,len);

    GetOpenFile(sock, fptr);
    if (getsockopt(fptr->fd, level, option, buf, &len) < 0)
	rb_sys_fail_path(fptr->pathv);

    return rb_str_new(buf, len);
#else
    rb_notimplement();
#endif
}

/*
 * call-seq:
 *   basicsocket.getsockname => sockaddr
 *
 * Returns the local address of the socket as a sockaddr string.
 *
 *   TCPServer.open("127.0.0.1", 15120) {|serv|
 *     p serv.getsockname #=> "\x02\x00;\x10\x7F\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00"
 *   }
 */
static VALUE
bsock_getsockname(VALUE sock)
{
    char buf[1024];
    socklen_t len = sizeof buf;
    rb_io_t *fptr;

    GetOpenFile(sock, fptr);
    if (getsockname(fptr->fd, (struct sockaddr*)buf, &len) < 0)
	rb_sys_fail("getsockname(2)");
    return rb_str_new(buf, len);
}

/*
 * call-seq:
 *   basicsocket.getpeername => sockaddr
 *
 * Returns the remote address of the socket as a sockaddr string.
 *
 *   TCPServer.open("127.0.0.1", 1440) {|serv|
 *     c = TCPSocket.new("127.0.0.1", 1440)
 *     s = serv.accept
 *     p s.getpeername #=> "\x02\x00\x82u\x7F\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00"
 *   }
 *
 */
static VALUE
bsock_getpeername(VALUE sock)
{
    char buf[1024];
    socklen_t len = sizeof buf;
    rb_io_t *fptr;

    GetOpenFile(sock, fptr);
    if (getpeername(fptr->fd, (struct sockaddr*)buf, &len) < 0)
	rb_sys_fail("getpeername(2)");
    return rb_str_new(buf, len);
}

static VALUE addrinfo_new(struct sockaddr *, socklen_t, int, int, int, VALUE, VALUE);

static int
get_afamily(struct sockaddr *addr, socklen_t len)
{
    if ((char*)&addr->sa_family + sizeof(addr->sa_family) - (char*)addr <= len)
        return addr->sa_family;
    else
        return AF_UNSPEC;
}

static VALUE
fd_socket_addrinfo(int fd, struct sockaddr *addr, socklen_t len)
{
    int family;
    int socktype;
    int ret;
    socklen_t optlen = sizeof(socktype);

    /* assumes protocol family and address family are identical */
    family = get_afamily(addr, len);

    ret = getsockopt(fd, SOL_SOCKET, SO_TYPE, (void*)&socktype, &optlen);
    if (ret == -1) {
	rb_sys_fail("getsockopt(SO_TYPE)");
    }

    return addrinfo_new(addr, len, family, socktype, 0, Qnil, Qnil);
}

static VALUE
io_socket_addrinfo(VALUE io, struct sockaddr *addr, socklen_t len)
{
    rb_io_t *fptr;

    switch (TYPE(io)) {
      case T_FIXNUM:
        return fd_socket_addrinfo(FIX2INT(io), addr, len);

      case T_BIGNUM:
        return fd_socket_addrinfo(NUM2INT(io), addr, len);

      case T_FILE:
        GetOpenFile(io, fptr);
        return fd_socket_addrinfo(fptr->fd, addr, len);

      default:
	rb_raise(rb_eTypeError, "neither IO nor file descriptor");
    }
}

/*
 * call-seq:
 *   bsock.local_address => addrinfo
 *
 * Returns an AddrInfo object for local address obtained by getsockname.
 *
 * Note that addrinfo.protocol is filled by 0.
 *
 *   TCPServer.open("127.0.0.1", 1512) {|serv|
 *     p serv.local_address #=> #<AddrInfo: 127.0.0.1:1512 TCP>
 *   }
 *
 */
static VALUE
bsock_local_address(VALUE sock)
{
    char buf[1024];
    socklen_t len = sizeof buf;
    rb_io_t *fptr;

    GetOpenFile(sock, fptr);
    if (getsockname(fptr->fd, (struct sockaddr*)buf, &len) < 0)
	rb_sys_fail("getsockname(2)");
    return fd_socket_addrinfo(fptr->fd, (struct sockaddr *)buf, len);
}

/*
 * call-seq:
 *   bsock.remote_address => addrinfo
 *
 * Returns an AddrInfo object for remote address obtained by getpeername.
 *
 * Note that addrinfo.protocol is filled by 0.
 *
 *   TCPServer.open("127.0.0.1", 1728) {|serv|
 *     c = TCPSocket.new("127.0.0.1", 1728)
 *     s = serv.accept
 *     p s.remote_address #=> #<AddrInfo: 127.0.0.1:36504 TCP>
 *   }
 *
 */
static VALUE
bsock_remote_address(VALUE sock)
{
    char buf[1024];
    socklen_t len = sizeof buf;
    rb_io_t *fptr;

    GetOpenFile(sock, fptr);
    if (getpeername(fptr->fd, (struct sockaddr*)buf, &len) < 0)
	rb_sys_fail("getpeername(2)");
    return fd_socket_addrinfo(fptr->fd, (struct sockaddr *)buf, len);
}

struct send_arg {
    int fd, flags;
    VALUE mesg;
    struct sockaddr *to;
    socklen_t tolen;
};

static VALUE
sendto_blocking(void *data)
{
    struct send_arg *arg = data;
    VALUE mesg = arg->mesg;
    return (VALUE)sendto(arg->fd, RSTRING_PTR(mesg), RSTRING_LEN(mesg),
			 arg->flags, arg->to, arg->tolen);
}

static VALUE
send_blocking(void *data)
{
    struct send_arg *arg = data;
    VALUE mesg = arg->mesg;
    return (VALUE)send(arg->fd, RSTRING_PTR(mesg), RSTRING_LEN(mesg),
		       arg->flags);
}

#define SockAddrStringValue(v) sockaddr_string_value(&(v))
#define SockAddrStringValuePtr(v) sockaddr_string_value_ptr(&(v))
static VALUE sockaddr_string_value(volatile VALUE *);
static char *sockaddr_string_value_ptr(volatile VALUE *);

/*
 * call-seq:
 *   basicsocket.send(mesg, flags [, sockaddr_to]) => numbytes_sent
 *
 * send _mesg_ via _basicsocket_.
 *
 * _mesg_ should be a string.
 *
 * _flags_ should be a bitwise OR of Socket::MSG_* constants.
 *
 * _sockaddr_to_ should be a packed sockaddr string or an addrinfo.
 *
 *   TCPSocket.open("localhost", 80) {|s|
 *     s.send "GET / HTTP/1.0\r\n\r\n", 0
 *     p s.read
 *   }
 */
static VALUE
bsock_send(int argc, VALUE *argv, VALUE sock)
{
    struct send_arg arg;
    VALUE flags, to;
    rb_io_t *fptr;
    int n;
    rb_blocking_function_t *func;

    rb_secure(4);
    rb_scan_args(argc, argv, "21", &arg.mesg, &flags, &to);

    StringValue(arg.mesg);
    if (!NIL_P(to)) {
	SockAddrStringValue(to);
	to = rb_str_new4(to);
	arg.to = (struct sockaddr *)RSTRING_PTR(to);
	arg.tolen = RSTRING_LEN(to);
	func = sendto_blocking;
    }
    else {
	func = send_blocking;
    }
    GetOpenFile(sock, fptr);
    arg.fd = fptr->fd;
    arg.flags = NUM2INT(flags);
    while (rb_thread_fd_writable(arg.fd),
	   (n = (int)BLOCKING_REGION(func, &arg)) < 0) {
	if (rb_io_wait_writable(arg.fd)) {
	    continue;
	}
	rb_sys_fail("send(2)");
    }
    return INT2FIX(n);
}

/*
 * call-seq:
 *   basicsocket.do_not_reverse_lookup => true or false
 *
 * Gets the do_not_reverse_lookup flag of _basicsocket_.
 *
 *   TCPSocket.open("www.ruby-lang.org", 80) {|sock|
 *     p sock.do_not_reverse_lookup      #=> false
 *     p sock.peeraddr                   #=> ["AF_INET", 80, "carbon.ruby-lang.org", "221.186.184.68"]
 *     sock.do_not_reverse_lookup = true
 *     p sock.peeraddr                   #=> ["AF_INET", 80, "221.186.184.68", "221.186.184.68"]
 *   }
 */
static VALUE
bsock_do_not_reverse_lookup(VALUE sock)
{
    rb_io_t *fptr;

    GetOpenFile(sock, fptr);
    return (fptr->mode & FMODE_NOREVLOOKUP) ? Qtrue : Qfalse;
}

/*
 * call-seq:
 *   basicsocket.do_not_reverse_lookup = bool
 *
 * Sets the do_not_reverse_lookup flag of _basicsocket_.
 *
 *   BasicSocket.do_not_reverse_lookup = false
 *   p TCPSocket.new("127.0.0.1", 80).do_not_reverse_lookup #=> false
 *   BasicSocket.do_not_reverse_lookup = true
 *   p TCPSocket.new("127.0.0.1", 80).do_not_reverse_lookup #=> true
 *
 */
static VALUE
bsock_do_not_reverse_lookup_set(VALUE sock, VALUE state)
{
    rb_io_t *fptr;

    rb_secure(4);
    GetOpenFile(sock, fptr);
    if (RTEST(state)) {
	fptr->mode |= FMODE_NOREVLOOKUP;
    }
    else {
	fptr->mode &= ~FMODE_NOREVLOOKUP;
    }
    return sock;
}

static VALUE ipaddr(struct sockaddr*, int);
#ifdef HAVE_SYS_UN_H
static VALUE unixaddr(struct sockaddr_un*, socklen_t);
#endif

enum sock_recv_type {
    RECV_RECV,			/* BasicSocket#recv(no from) */
    RECV_IP,			/* IPSocket#recvfrom */
    RECV_UNIX,			/* UNIXSocket#recvfrom */
    RECV_SOCKET			/* Socket#recvfrom */
};

struct recvfrom_arg {
    int fd, flags;
    VALUE str;
    socklen_t alen;
    char buf[1024];
};

static VALUE
recvfrom_blocking(void *data)
{
    struct recvfrom_arg *arg = data;
    return (VALUE)recvfrom(arg->fd, RSTRING_PTR(arg->str), RSTRING_LEN(arg->str),
			   arg->flags, (struct sockaddr*)arg->buf, &arg->alen);
}

static VALUE
s_recvfrom(VALUE sock, int argc, VALUE *argv, enum sock_recv_type from)
{
    rb_io_t *fptr;
    VALUE str, klass;
    struct recvfrom_arg arg;
    VALUE len, flg;
    long buflen;
    long slen;

    rb_scan_args(argc, argv, "11", &len, &flg);

    if (flg == Qnil) arg.flags = 0;
    else             arg.flags = NUM2INT(flg);
    buflen = NUM2INT(len);

    GetOpenFile(sock, fptr);
    if (rb_io_read_pending(fptr)) {
	rb_raise(rb_eIOError, "recv for buffered IO");
    }
    arg.fd = fptr->fd;
    arg.alen = sizeof(arg.buf);

    arg.str = str = rb_tainted_str_new(0, buflen);
    klass = RBASIC(str)->klass;
    RBASIC(str)->klass = 0;

    while (rb_io_check_closed(fptr),
	   rb_thread_wait_fd(arg.fd),
	   (slen = BLOCKING_REGION(recvfrom_blocking, &arg)) < 0) {
	if (RBASIC(str)->klass || RSTRING_LEN(str) != buflen) {
	    rb_raise(rb_eRuntimeError, "buffer string modified");
	}
    }

    RBASIC(str)->klass = klass;
    if (slen < RSTRING_LEN(str)) {
	rb_str_set_len(str, slen);
    }
    rb_obj_taint(str);
    switch (from) {
      case RECV_RECV:
	return str;
      case RECV_IP:
#if 0
	if (arg.alen != sizeof(struct sockaddr_in)) {
	    rb_raise(rb_eTypeError, "sockaddr size differs - should not happen");
	}
#endif
	if (arg.alen && arg.alen != sizeof(arg.buf)) /* OSX doesn't return a from result for connection-oriented sockets */
	    return rb_assoc_new(str, ipaddr((struct sockaddr*)arg.buf, fptr->mode & FMODE_NOREVLOOKUP));
	else
	    return rb_assoc_new(str, Qnil);

#ifdef HAVE_SYS_UN_H
      case RECV_UNIX:
        return rb_assoc_new(str, unixaddr((struct sockaddr_un*)arg.buf, arg.alen));
#endif
      case RECV_SOCKET:
	return rb_assoc_new(str, io_socket_addrinfo(sock, (struct sockaddr*)arg.buf, arg.alen));
      default:
	rb_bug("s_recvfrom called with bad value");
    }
}

static VALUE
s_recvfrom_nonblock(VALUE sock, int argc, VALUE *argv, enum sock_recv_type from)
{
    rb_io_t *fptr;
    VALUE str;
    char buf[1024];
    socklen_t alen = sizeof buf;
    VALUE len, flg;
    long buflen;
    long slen;
    int fd, flags;
    VALUE addr = Qnil;

    rb_scan_args(argc, argv, "11", &len, &flg);

    if (flg == Qnil) flags = 0;
    else             flags = NUM2INT(flg);
    buflen = NUM2INT(len);

#ifdef MSG_DONTWAIT
    /* MSG_DONTWAIT avoids the race condition between fcntl and recvfrom.
       It is not portable, though. */
    flags |= MSG_DONTWAIT;
#endif

    GetOpenFile(sock, fptr);
    if (rb_io_read_pending(fptr)) {
	rb_raise(rb_eIOError, "recvfrom for buffered IO");
    }
    fd = fptr->fd;

    str = rb_tainted_str_new(0, buflen);

    rb_io_check_closed(fptr);
    rb_io_set_nonblock(fptr);
    slen = recvfrom(fd, RSTRING_PTR(str), buflen, flags, (struct sockaddr*)buf, &alen);

    if (slen < 0) {
	rb_sys_fail("recvfrom(2)");
    }
    if (slen < RSTRING_LEN(str)) {
	rb_str_set_len(str, slen);
    }
    rb_obj_taint(str);
    switch (from) {
      case RECV_RECV:
        return str;

      case RECV_IP:
        if (alen && alen != sizeof(buf)) /* connection-oriented socket may not return a from result */
            addr = ipaddr((struct sockaddr*)buf, fptr->mode & FMODE_NOREVLOOKUP);
        break;

      case RECV_SOCKET:
        addr = io_socket_addrinfo(sock, (struct sockaddr*)buf, alen);
        break;

      default:
        rb_bug("s_recvfrom_nonblock called with bad value");
    }
    return rb_assoc_new(str, addr);
}

/*
 * call-seq:
 *   basicsocket.recv(maxlen) => mesg
 *   basicsocket.recv(maxlen, flags) => mesg
 *
 * Receives a message.
 *
 * _maxlen_ is the maximum number of bytes to receive.
 *
 * _flags_ should be a bitwise OR of Socket::MSG_* constants.
 *
 *   UNIXSocket.pair {|s1, s2|
 *     s1.puts "Hello World"
 *     p s2.recv(4)                     #=> "Hell"
 *     p s2.recv(4, Socket::MSG_PEEK)   #=> "o Wo"
 *     p s2.recv(4)                     #=> "o Wo"
 *     p s2.recv(10)                    #=> "rld\n"
 *   }
 */
static VALUE
bsock_recv(int argc, VALUE *argv, VALUE sock)
{
    return s_recvfrom(sock, argc, argv, RECV_RECV);
}

/*
 * call-seq:
 * 	basicsocket.recv_nonblock(maxlen) => mesg
 * 	basicsocket.recv_nonblock(maxlen, flags) => mesg
 * 
 * Receives up to _maxlen_ bytes from +socket+ using recvfrom(2) after
 * O_NONBLOCK is set for the underlying file descriptor.
 * _flags_ is zero or more of the +MSG_+ options.
 * The result, _mesg_, is the data received.
 *
 * When recvfrom(2) returns 0, Socket#recv_nonblock returns
 * an empty string as data.
 * The meaning depends on the socket: EOF on TCP, empty packet on UDP, etc.
 * 
 * === Parameters
 * * +maxlen+ - the number of bytes to receive from the socket
 * * +flags+ - zero or more of the +MSG_+ options 
 * 
 * === Example
 * 	serv = TCPServer.new("127.0.0.1", 0)
 * 	af, port, host, addr = serv.addr
 * 	c = TCPSocket.new(addr, port)
 * 	s = serv.accept
 * 	c.send "aaa", 0
 * 	IO.select([s]) # emulate blocking recv.
 * 	p s.recv_nonblock(10) #=> "aaa"
 *
 * Refer to Socket#recvfrom for the exceptions that may be thrown if the call
 * to _recv_nonblock_ fails. 
 *
 * BasicSocket#recv_nonblock may raise any error corresponding to recvfrom(2) failure,
 * including Errno::EWOULDBLOCK.
 *
 * === See
 * * Socket#recvfrom
 */

static VALUE
bsock_recv_nonblock(int argc, VALUE *argv, VALUE sock)
{
    return s_recvfrom_nonblock(sock, argc, argv, RECV_RECV);
}

/*
 * call-seq:
 *   BasicSocket.do_not_reverse_lookup => true or false
 *
 * Gets the global do_not_reverse_lookup flag.
 *
 *   BasicSocket.do_not_reverse_lookup  #=> false
 */
static VALUE
bsock_do_not_rev_lookup(void)
{
    return do_not_reverse_lookup?Qtrue:Qfalse;
}

/*
 * call-seq:
 *   BasicSocket.do_not_reverse_lookup = bool
 *
 * Sets the global do_not_reverse_lookup flag.
 *
 * The flag is used for initial value of do_not_reverse_lookup for each socket.
 *
 *   s1 = TCPSocket.new("localhost", 80)
 *   p s1.do_not_reverse_lookup                 #=> true
 *   BasicSocket.do_not_reverse_lookup = false
 *   s2 = TCPSocket.new("localhost", 80)
 *   p s2.do_not_reverse_lookup                 #=> false
 *   p s1.do_not_reverse_lookup                 #=> true
 *
 */
static VALUE
bsock_do_not_rev_lookup_set(VALUE self, VALUE val)
{
    rb_secure(4);
    do_not_reverse_lookup = RTEST(val);
    return val;
}

NORETURN(static void raise_socket_error(const char *, int));
static void
raise_socket_error(const char *reason, int error)
{
#ifdef EAI_SYSTEM
    if (error == EAI_SYSTEM) rb_sys_fail(reason);
#endif
    rb_raise(rb_eSocket, "%s: %s", reason, gai_strerror(error));
}

static void
make_ipaddr0(struct sockaddr *addr, char *buf, size_t len)
{
    int error;

    error = rb_getnameinfo(addr, SA_LEN(addr), buf, len, NULL, 0, NI_NUMERICHOST);
    if (error) {
	raise_socket_error("getnameinfo", error);
    }
}

static VALUE
make_ipaddr(struct sockaddr *addr)
{
    char buf[1024];

    make_ipaddr0(addr, buf, sizeof(buf));
    return rb_str_new2(buf);
}

static void
make_inetaddr(long host, char *buf, size_t len)
{
    struct sockaddr_in sin;

    MEMZERO(&sin, struct sockaddr_in, 1);
    sin.sin_family = AF_INET;
    SET_SIN_LEN(&sin, sizeof(sin));
    sin.sin_addr.s_addr = host;
    make_ipaddr0((struct sockaddr*)&sin, buf, len);
}

static int
str_isnumber(const char *p)
{
    char *ep;

    if (!p || *p == '\0')
       return 0;
    ep = NULL;
    (void)STRTOUL(p, &ep, 10);
    if (ep && *ep == '\0')
       return 1;
    else
       return 0;
}

static char*
host_str(VALUE host, char *hbuf, size_t len, int *flags_ptr)
{
    if (NIL_P(host)) {
	return NULL;
    }
    else if (rb_obj_is_kind_of(host, rb_cInteger)) {
	unsigned long i = NUM2ULONG(host);

	make_inetaddr(htonl(i), hbuf, len);
        if (flags_ptr) *flags_ptr |= AI_NUMERICHOST;
	return hbuf;
    }
    else {
	char *name;

	SafeStringValue(host);
	name = RSTRING_PTR(host);
	if (!name || *name == 0 || (name[0] == '<' && strcmp(name, "<any>") == 0)) {
	    make_inetaddr(INADDR_ANY, hbuf, len);
            if (flags_ptr) *flags_ptr |= AI_NUMERICHOST;
	}
	else if (name[0] == '<' && strcmp(name, "<broadcast>") == 0) {
	    make_inetaddr(INADDR_BROADCAST, hbuf, len);
            if (flags_ptr) *flags_ptr |= AI_NUMERICHOST;
	}
	else if (strlen(name) >= len) {
	    rb_raise(rb_eArgError, "hostname too long (%"PRIuSIZE")",
                strlen(name));
	}
	else {
	    strcpy(hbuf, name);
	}
	return hbuf;
    }
}

static char*
port_str(VALUE port, char *pbuf, size_t len, int *flags_ptr)
{
    if (NIL_P(port)) {
	return 0;
    }
    else if (FIXNUM_P(port)) {
	snprintf(pbuf, len, "%ld", FIX2LONG(port));
#ifdef AI_NUMERICSERV
        if (flags_ptr) *flags_ptr |= AI_NUMERICSERV;
#endif
	return pbuf;
    }
    else {
	char *serv;

	SafeStringValue(port);
	serv = RSTRING_PTR(port);
	if (strlen(serv) >= len) {
	    rb_raise(rb_eArgError, "service name too long (%"PRIuSIZE")",
                strlen(serv));
	}
	strcpy(pbuf, serv);
	return pbuf;
    }
}

#ifndef NI_MAXHOST
# define NI_MAXHOST 1025
#endif
#ifndef NI_MAXSERV
# define NI_MAXSERV 32
#endif

static struct addrinfo*
sock_getaddrinfo(VALUE host, VALUE port, struct addrinfo *hints, int socktype_hack)
{
    struct addrinfo* res = NULL;
    char *hostp, *portp;
    int error;
    char hbuf[NI_MAXHOST], pbuf[NI_MAXSERV];
    int additional_flags = 0;

    hostp = host_str(host, hbuf, sizeof(hbuf), &additional_flags);
    portp = port_str(port, pbuf, sizeof(pbuf), &additional_flags);

    if (socktype_hack && hints->ai_socktype == 0 && str_isnumber(portp)) {
       hints->ai_socktype = SOCK_DGRAM;
    }
    hints->ai_flags |= additional_flags;

    error = rb_getaddrinfo(hostp, portp, hints, &res);
    if (error) {
	if (hostp && hostp[strlen(hostp)-1] == '\n') {
	    rb_raise(rb_eSocket, "newline at the end of hostname");
	}
	raise_socket_error("getaddrinfo", error);
    }

#if defined(__APPLE__) && defined(__MACH__)
    {
	struct addrinfo *r;
	r = res;
	while (r) {
	    if (! r->ai_socktype) r->ai_socktype = hints->ai_socktype;
	    if (! r->ai_protocol) {
		if (r->ai_socktype == SOCK_DGRAM) {
		    r->ai_protocol = IPPROTO_UDP;
		}
		else if (r->ai_socktype == SOCK_STREAM) {
		    r->ai_protocol = IPPROTO_TCP;
		}
	    }
	    r = r->ai_next;
	}
    }
#endif
    return res;
}

static struct addrinfo*
sock_addrinfo(VALUE host, VALUE port, int socktype, int flags)
{
    struct addrinfo hints;

    MEMZERO(&hints, struct addrinfo, 1);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = socktype;
    hints.ai_flags = flags;
    return sock_getaddrinfo(host, port, &hints, 1);
}

static VALUE
ipaddr(struct sockaddr *sockaddr, int norevlookup)
{
    VALUE family, port, addr1, addr2;
    VALUE ary;
    int error;
    char hbuf[1024], pbuf[1024];
    ID id;

    id = intern_family(sockaddr->sa_family);
    if (id) {
        family = rb_str_dup(rb_id2str(id));
    }
    else {
        sprintf(pbuf, "unknown:%d", sockaddr->sa_family);
	family = rb_str_new2(pbuf);
    }

    addr1 = Qnil;
    if (!norevlookup) {
	error = rb_getnameinfo(sockaddr, SA_LEN(sockaddr), hbuf, sizeof(hbuf),
			       NULL, 0, 0);
	if (! error) {
	    addr1 = rb_str_new2(hbuf);
	}
    }
    error = rb_getnameinfo(sockaddr, SA_LEN(sockaddr), hbuf, sizeof(hbuf),
			   pbuf, sizeof(pbuf), NI_NUMERICHOST | NI_NUMERICSERV);
    if (error) {
	raise_socket_error("getnameinfo", error);
    }
    addr2 = rb_str_new2(hbuf);
    if (addr1 == Qnil) {
	addr1 = addr2;
    }
    port = INT2FIX(atoi(pbuf));
    ary = rb_ary_new3(4, family, port, addr1, addr2);

    return ary;
}

static int
ruby_socket(int domain, int type, int proto)
{
    int fd;

    fd = socket(domain, type, proto);
    if (fd < 0) {
	if (errno == EMFILE || errno == ENFILE) {
	    rb_gc();
	    fd = socket(domain, type, proto);
	}
    }
    return fd;
}

static int
wait_connectable0(int fd, rb_fdset_t *fds_w, rb_fdset_t *fds_e)
{
    int sockerr;
    socklen_t sockerrlen;

    for (;;) {
	rb_fd_zero(fds_w);
	rb_fd_zero(fds_e);

	rb_fd_set(fd, fds_w);
	rb_fd_set(fd, fds_e);

	rb_thread_select(fd+1, 0, rb_fd_ptr(fds_w), rb_fd_ptr(fds_e), 0);

	if (rb_fd_isset(fd, fds_w)) {
	    return 0;
	}
	else if (rb_fd_isset(fd, fds_e)) {
	    sockerrlen = sizeof(sockerr);
	    if (getsockopt(fd, SOL_SOCKET, SO_ERROR, (void *)&sockerr,
			   &sockerrlen) == 0) {
		if (sockerr == 0)
		    continue;	/* workaround for winsock */
		errno = sockerr;
	    }
	    return -1;
	}
    }

    return 0;
}

struct wait_connectable_arg {
    int fd;
    rb_fdset_t fds_w;
    rb_fdset_t fds_e;
};

#ifdef HAVE_RB_FD_INIT
static VALUE
try_wait_connectable(VALUE arg)
{
    struct wait_connectable_arg *p = (struct wait_connectable_arg *)arg;
    return (VALUE)wait_connectable0(p->fd, &p->fds_w, &p->fds_e);
}

static VALUE
wait_connectable_ensure(VALUE arg)
{
    struct wait_connectable_arg *p = (struct wait_connectable_arg *)arg;
    rb_fd_term(&p->fds_w);
    rb_fd_term(&p->fds_e);
    return Qnil;
}
#endif

static int
wait_connectable(int fd)
{
    struct wait_connectable_arg arg;

    rb_fd_init(&arg.fds_w);
    rb_fd_init(&arg.fds_e);
#ifdef HAVE_RB_FD_INIT
    arg.fd = fd;
    return (int)rb_ensure(try_wait_connectable, (VALUE)&arg,
			  wait_connectable_ensure,(VALUE)&arg);
#else
    return wait_connectable0(fd, &arg.fds_w, &arg.fds_e);
#endif
}

#ifdef __CYGWIN__
#define WAIT_IN_PROGRESS 10
#endif
#ifdef __APPLE__
#define WAIT_IN_PROGRESS 10
#endif
#ifdef __linux__
/* returns correct error */
#define WAIT_IN_PROGRESS 0
#endif
#ifndef WAIT_IN_PROGRESS
/* BSD origin code apparently has a problem */
#define WAIT_IN_PROGRESS 1
#endif

struct connect_arg {
    int fd;
    const struct sockaddr *sockaddr;
    socklen_t len;
};

static VALUE
connect_blocking(void *data)
{
    struct connect_arg *arg = data;
    return (VALUE)connect(arg->fd, arg->sockaddr, arg->len);
}

#if defined(SOCKS) && !defined(SOCKS5)
static VALUE
socks_connect_blocking(void *data)
{
    struct connect_arg *arg = data;
    return (VALUE)Rconnect(arg->fd, arg->sockaddr, arg->len);
}
#endif

static int
ruby_connect(int fd, const struct sockaddr *sockaddr, int len, int socks)
{
    int status;
    rb_blocking_function_t *func = connect_blocking;
    struct connect_arg arg;
#if WAIT_IN_PROGRESS > 0
    int wait_in_progress = -1;
    int sockerr;
    socklen_t sockerrlen;
#endif

    arg.fd = fd;
    arg.sockaddr = sockaddr;
    arg.len = len;
#if defined(SOCKS) && !defined(SOCKS5)
    if (socks) func = socks_connect_blocking;
#endif
    for (;;) {
	status = (int)BLOCKING_REGION(func, &arg);
	if (status < 0) {
	    switch (errno) {
	      case EAGAIN:
#ifdef EINPROGRESS
	      case EINPROGRESS:
#endif
#if WAIT_IN_PROGRESS > 0
		sockerrlen = sizeof(sockerr);
		status = getsockopt(fd, SOL_SOCKET, SO_ERROR, (void *)&sockerr, &sockerrlen);
		if (status) break;
		if (sockerr) {
		    status = -1;
		    errno = sockerr;
		    break;
		}
#endif
#ifdef EALREADY
	      case EALREADY:
#endif
#if WAIT_IN_PROGRESS > 0
		wait_in_progress = WAIT_IN_PROGRESS;
#endif
		status = wait_connectable(fd);
		if (status) {
		    break;
		}
		errno = 0;
		continue;

#if WAIT_IN_PROGRESS > 0
	      case EINVAL:
		if (wait_in_progress-- > 0) {
		    /*
		     * connect() after EINPROGRESS returns EINVAL on
		     * some platforms, need to check true error
		     * status.
		     */
		    sockerrlen = sizeof(sockerr);
		    status = getsockopt(fd, SOL_SOCKET, SO_ERROR, (void *)&sockerr, &sockerrlen);
		    if (!status && !sockerr) {
			struct timeval tv = {0, 100000};
			rb_thread_wait_for(tv);
			continue;
		    }
		    status = -1;
		    errno = sockerr;
		}
		break;
#endif

#ifdef EISCONN
	      case EISCONN:
		status = 0;
		errno = 0;
		break;
#endif
	      default:
		break;
	    }
	}
	return status;
    }
}

struct inetsock_arg
{
    VALUE sock;
    struct {
	VALUE host, serv;
	struct addrinfo *res;
    } remote, local;
    int type;
    int fd;
};

static VALUE
inetsock_cleanup(struct inetsock_arg *arg)
{
    if (arg->remote.res) {
	freeaddrinfo(arg->remote.res);
	arg->remote.res = 0;
    }
    if (arg->local.res) {
	freeaddrinfo(arg->local.res);
	arg->local.res = 0;
    }
    if (arg->fd >= 0) {
	close(arg->fd);
    }
    return Qnil;
}

static VALUE
init_inetsock_internal(struct inetsock_arg *arg)
{
    int type = arg->type;
    struct addrinfo *res;
    int fd, status = 0;
    const char *syscall = 0;

    arg->remote.res = sock_addrinfo(arg->remote.host, arg->remote.serv, SOCK_STREAM,
				    (type == INET_SERVER) ? AI_PASSIVE : 0);
    /*
     * Maybe also accept a local address
     */

    if (type != INET_SERVER && (!NIL_P(arg->local.host) || !NIL_P(arg->local.serv))) {
	arg->local.res = sock_addrinfo(arg->local.host, arg->local.serv, SOCK_STREAM, 0);
    }

    arg->fd = fd = -1;
    for (res = arg->remote.res; res; res = res->ai_next) {
	status = ruby_socket(res->ai_family,res->ai_socktype,res->ai_protocol);
	syscall = "socket(2)";
	fd = status;
	if (fd < 0) {
	    continue;
	}
	arg->fd = fd;
	if (type == INET_SERVER) {
#if !defined(_WIN32) && !defined(__CYGWIN__)
	    status = 1;
	    setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
		       (char*)&status, sizeof(status));
#endif
	    status = bind(fd, res->ai_addr, res->ai_addrlen);
	    syscall = "bind(2)";
	}
	else {
	    if (arg->local.res) {
		status = bind(fd, arg->local.res->ai_addr, arg->local.res->ai_addrlen);
		syscall = "bind(2)";
	    }

	    if (status >= 0) {
		status = ruby_connect(fd, res->ai_addr, res->ai_addrlen,
				      (type == INET_SOCKS));
		syscall = "connect(2)";
	    }
	}

	if (status < 0) {
	    close(fd);
	    arg->fd = fd = -1;
	    continue;
	} else
	    break;
    }
    if (status < 0) {
	rb_sys_fail(syscall);
    }

    arg->fd = -1;

    if (type == INET_SERVER)
	listen(fd, 5);

    /* create new instance */
    return init_sock(arg->sock, fd);
}

static VALUE
init_inetsock(VALUE sock, VALUE remote_host, VALUE remote_serv,
	      VALUE local_host, VALUE local_serv, int type)
{
    struct inetsock_arg arg;
    arg.sock = sock;
    arg.remote.host = remote_host;
    arg.remote.serv = remote_serv;
    arg.remote.res = 0;
    arg.local.host = local_host;
    arg.local.serv = local_serv;
    arg.local.res = 0;
    arg.type = type;
    arg.fd = -1;
    return rb_ensure(init_inetsock_internal, (VALUE)&arg,
		     inetsock_cleanup, (VALUE)&arg);
}

/*
 * call-seq:
 *    TCPSocket.new(remote_host, remote_port, local_host=nil, local_port=nil)
 *
 * Opens a TCP connection to +remote_host+ on +remote_port+.  If +local_host+
 * and +local_port+ are specified, then those parameters are used on the local
 * end to establish the connection.
 */
static VALUE
tcp_init(int argc, VALUE *argv, VALUE sock)
{
    VALUE remote_host, remote_serv;
    VALUE local_host, local_serv;

    rb_scan_args(argc, argv, "22", &remote_host, &remote_serv,
			&local_host, &local_serv);

    return init_inetsock(sock, remote_host, remote_serv,
			local_host, local_serv, INET_CLIENT);
}

#ifdef SOCKS
static VALUE
socks_init(VALUE sock, VALUE host, VALUE serv)
{
    static init = 0;

    if (init == 0) {
	SOCKSinit("ruby");
	init = 1;
    }

    return init_inetsock(sock, host, serv, Qnil, Qnil, INET_SOCKS);
}

#ifdef SOCKS5
static VALUE
socks_s_close(VALUE sock)
{
    rb_io_t *fptr;

    if (rb_safe_level() >= 4 && !OBJ_TAINTED(sock)) {
	rb_raise(rb_eSecurityError, "Insecure: can't close socket");
    }
    GetOpenFile(sock, fptr);
    shutdown(fptr->fd, 2);
    return rb_io_close(sock);
}
#endif
#endif

struct hostent_arg {
    VALUE host;
    struct addrinfo* addr;
    VALUE (*ipaddr)(struct sockaddr*, size_t);
};

static VALUE
make_hostent_internal(struct hostent_arg *arg)
{
    VALUE host = arg->host;
    struct addrinfo* addr = arg->addr;
    VALUE (*ipaddr)(struct sockaddr*, size_t) = arg->ipaddr;

    struct addrinfo *ai;
    struct hostent *h;
    VALUE ary, names;
    char **pch;
    const char* hostp;
    char hbuf[NI_MAXHOST];

    ary = rb_ary_new();
    if (addr->ai_canonname) {
	hostp = addr->ai_canonname;
    }
    else {
	hostp = host_str(host, hbuf, sizeof(hbuf), NULL);
    }
    rb_ary_push(ary, rb_str_new2(hostp));

    if (addr->ai_canonname && (h = gethostbyname(addr->ai_canonname))) {
	names = rb_ary_new();
	if (h->h_aliases != NULL) {
	    for (pch = h->h_aliases; *pch; pch++) {
		rb_ary_push(names, rb_str_new2(*pch));
	    }
	}
    }
    else {
	names = rb_ary_new2(0);
    }
    rb_ary_push(ary, names);
    rb_ary_push(ary, INT2NUM(addr->ai_family));
    for (ai = addr; ai; ai = ai->ai_next) {
	rb_ary_push(ary, (*ipaddr)(ai->ai_addr, ai->ai_addrlen));
    }

    return ary;
}

static VALUE
make_hostent(VALUE host, struct addrinfo *addr, VALUE (*ipaddr)(struct sockaddr *, size_t))
{
    struct hostent_arg arg;

    arg.host = host;
    arg.addr = addr;
    arg.ipaddr = ipaddr;
    return rb_ensure(make_hostent_internal, (VALUE)&arg,
		     RUBY_METHOD_FUNC(freeaddrinfo), (VALUE)addr);
}

static VALUE
tcp_sockaddr(struct sockaddr *addr, size_t len)
{
    return make_ipaddr(addr);
}

/*
 * call-seq:
 *   TCPSocket.gethostbyname(hostname) => [official_hostname, alias_hostnames, address_family, *address_list]
 *
 * Lookups host information by _hostname_.
 *
 *   TCPSocket.gethostbyname("localhost")
 *   #=> ["localhost", ["hal"], 2, "127.0.0.1"]
 *
 */
static VALUE
tcp_s_gethostbyname(VALUE obj, VALUE host)
{
    rb_secure(3);
    return make_hostent(host, sock_addrinfo(host, Qnil, SOCK_STREAM, AI_CANONNAME),
			tcp_sockaddr);
}

/*
 * call-seq:
 *   TCPServer.new([hostname,] port)                    => tcpserver
 *
 * Creates a new server socket bound to _port_.
 *
 * If _hostname_ is given, the socket is bound to it.
 *
 *   serv = TCPServer.new("127.0.0.1", 28561)
 *   s = serv.accept
 *   s.puts Time.now
 *   s.close
 */
static VALUE
tcp_svr_init(int argc, VALUE *argv, VALUE sock)
{
    VALUE arg1, arg2;

    if (rb_scan_args(argc, argv, "11", &arg1, &arg2) == 2)
	return init_inetsock(sock, arg1, arg2, Qnil, Qnil, INET_SERVER);
    else
	return init_inetsock(sock, Qnil, arg1, Qnil, Qnil, INET_SERVER);
}

static void
make_fd_nonblock(int fd)
{
    int flags;
#ifdef F_GETFL
    flags = fcntl(fd, F_GETFL);
    if (flags == -1) {
        rb_sys_fail(0);
    }
#else
    flags = 0;
#endif
    flags |= O_NONBLOCK;
    if (fcntl(fd, F_SETFL, flags) == -1) {
        rb_sys_fail(0);
    }
}

static VALUE
s_accept_nonblock(VALUE klass, rb_io_t *fptr, struct sockaddr *sockaddr, socklen_t *len)
{
    int fd2;

    rb_secure(3);
    rb_io_set_nonblock(fptr);
    fd2 = accept(fptr->fd, (struct sockaddr*)sockaddr, len);
    if (fd2 < 0) {
        rb_sys_fail("accept(2)");
    }
    make_fd_nonblock(fd2);
    return init_sock(rb_obj_alloc(klass), fd2);
}

struct accept_arg {
    int fd;
    struct sockaddr *sockaddr;
    socklen_t *len;
};

static VALUE
accept_blocking(void *data)
{
    struct accept_arg *arg = data;
    return (VALUE)accept(arg->fd, arg->sockaddr, arg->len);
}

static VALUE
s_accept(VALUE klass, int fd, struct sockaddr *sockaddr, socklen_t *len)
{
    int fd2;
    int retry = 0;
    struct accept_arg arg;

    rb_secure(3);
    arg.fd = fd;
    arg.sockaddr = sockaddr;
    arg.len = len;
  retry:
    rb_thread_wait_fd(fd);
    fd2 = BLOCKING_REGION(accept_blocking, &arg);
    if (fd2 < 0) {
	switch (errno) {
	  case EMFILE:
	  case ENFILE:
	    if (retry) break;
	    rb_gc();
	    retry = 1;
	    goto retry;
	  default:
	    if (!rb_io_wait_readable(fd)) break;
	    retry = 0;
	    goto retry;
	}
	rb_sys_fail(0);
    }
    if (!klass) return INT2NUM(fd2);
    return init_sock(rb_obj_alloc(klass), fd2);
}

/*
 * call-seq:
 *   tcpserver.accept => tcpsocket
 *
 *   TCPServer.open("127.0.0.1", 14641) {|serv|
 *     s = serv.accept
 *     s.puts Time.now
 *     s.close
 *   }
 *   
 */
static VALUE
tcp_accept(VALUE sock)
{
    rb_io_t *fptr;
    struct sockaddr_storage from;
    socklen_t fromlen;
 
    GetOpenFile(sock, fptr);
    fromlen = sizeof(from);
    return s_accept(rb_cTCPSocket, fptr->fd,
		    (struct sockaddr*)&from, &fromlen);
}

/*
 * call-seq:
 * 	tcpserver.accept_nonblock => tcpsocket
 * 
 * Accepts an incoming connection using accept(2) after
 * O_NONBLOCK is set for the underlying file descriptor.
 * It returns an accepted TCPSocket for the incoming connection.
 * 
 * === Example
 * 	require 'socket'
 * 	serv = TCPServer.new(2202)
 * 	begin # emulate blocking accept
 * 	  sock = serv.accept_nonblock
 * 	rescue Errno::EAGAIN, Errno::EWOULDBLOCK, Errno::ECONNABORTED, Errno::EPROTO, Errno::EINTR
 * 	  IO.select([serv])
 * 	  retry
 * 	end
 * 	# sock is an accepted socket.
 * 
 * Refer to Socket#accept for the exceptions that may be thrown if the call
 * to TCPServer#accept_nonblock fails. 
 *
 * TCPServer#accept_nonblock may raise any error corresponding to accept(2) failure,
 * including Errno::EWOULDBLOCK.
 * 
 * === See
 * * TCPServer#accept
 * * Socket#accept
 */
static VALUE
tcp_accept_nonblock(VALUE sock)
{
    rb_io_t *fptr;
    struct sockaddr_storage from;
    socklen_t fromlen;

    GetOpenFile(sock, fptr);
    fromlen = sizeof(from);
    return s_accept_nonblock(rb_cTCPSocket, fptr,
			     (struct sockaddr *)&from, &fromlen);
}

/*
 * call-seq:
 *   tcpserver.sysaccept => file_descriptor
 *
 * Returns a file descriptor of a accepted connection.
 *
 *   TCPServer.open("127.0.0.1", 28561) {|serv|
 *     fd = serv.sysaccept
 *     s = IO.for_fd(fd)       
 *     s.puts Time.now
 *     s.close
 *   }
 *
 */
static VALUE
tcp_sysaccept(VALUE sock)
{
    rb_io_t *fptr;
    struct sockaddr_storage from;
    socklen_t fromlen;

    GetOpenFile(sock, fptr);
    fromlen = sizeof(from);
    return s_accept(0, fptr->fd, (struct sockaddr*)&from, &fromlen);
}

#ifdef HAVE_SYS_UN_H
struct unixsock_arg {
    struct sockaddr_un *sockaddr;
    int fd;
};

static VALUE
unixsock_connect_internal(struct unixsock_arg *arg)
{
    return (VALUE)ruby_connect(arg->fd, (struct sockaddr*)arg->sockaddr,
			       sizeof(*arg->sockaddr), 0);
}

static VALUE
init_unixsock(VALUE sock, VALUE path, int server)
{
    struct sockaddr_un sockaddr;
    int fd, status;
    rb_io_t *fptr;

    SafeStringValue(path);
    fd = ruby_socket(AF_UNIX, SOCK_STREAM, 0);
    if (fd < 0) {
	rb_sys_fail("socket(2)");
    }

    MEMZERO(&sockaddr, struct sockaddr_un, 1);
    sockaddr.sun_family = AF_UNIX;
    if (sizeof(sockaddr.sun_path) <= RSTRING_LEN(path)) {
        rb_raise(rb_eArgError, "too long unix socket path (max: %dbytes)",
            (int)sizeof(sockaddr.sun_path)-1);
    }
    memcpy(sockaddr.sun_path, RSTRING_PTR(path), RSTRING_LEN(path));

    if (server) {
        status = bind(fd, (struct sockaddr*)&sockaddr, sizeof(sockaddr));
    }
    else {
	int prot;
	struct unixsock_arg arg;
	arg.sockaddr = &sockaddr;
	arg.fd = fd;
        status = rb_protect((VALUE(*)(VALUE))unixsock_connect_internal,
			    (VALUE)&arg, &prot);
	if (prot) {
	    close(fd);
	    rb_jump_tag(prot);
	}
    }

    if (status < 0) {
	close(fd);
	rb_sys_fail(sockaddr.sun_path);
    }

    if (server) listen(fd, 5);

    init_sock(sock, fd);
    if (server) {
	GetOpenFile(sock, fptr);
        fptr->pathv = rb_str_new_frozen(path);
    }

    return sock;
}
#endif

/*
 * call-seq:
 *   ipsocket.addr => [address_family, port, hostname, numeric_address] 
 *
 * Returns the local address as an array which contains
 * address_family, port, hostname and numeric_address. 
 *
 * hostname is obtained from numeric_address using reverse lookup.
 * If ipsocket.do_not_reverse_lookup is true,
 * hostname is same as numeric_address.
 *
 *   TCPSocket.open("www.ruby-lang.org", 80) {|sock|
 *     p sock.addr #=> ["AF_INET", 49429, "hal", "192.168.0.128"]
 *   }
 *
 */
static VALUE
ip_addr(VALUE sock)
{
    rb_io_t *fptr;
    struct sockaddr_storage addr;
    socklen_t len = sizeof addr;

    GetOpenFile(sock, fptr);

    if (getsockname(fptr->fd, (struct sockaddr*)&addr, &len) < 0)
	rb_sys_fail("getsockname(2)");
    return ipaddr((struct sockaddr*)&addr, fptr->mode & FMODE_NOREVLOOKUP);
}

/*
 * call-seq:
 *   ipsocket.peeraddr => [address_family, port, hostname, numeric_address] 
 *
 * Returns the remote address as an array which contains
 * address_family, port, hostname and numeric_address. 
 * It is defined for connection oritented socket such as TCPSocket.
 *
 *   TCPSocket.open("www.ruby-lang.org", 80) {|sock|
 *     p sock.peeraddr #=> ["AF_INET", 80, "carbon.ruby-lang.org", "221.186.184.68"]
 *   }
 *
 */
static VALUE
ip_peeraddr(VALUE sock)
{
    rb_io_t *fptr;
    struct sockaddr_storage addr;
    socklen_t len = sizeof addr;

    GetOpenFile(sock, fptr);

    if (getpeername(fptr->fd, (struct sockaddr*)&addr, &len) < 0)
	rb_sys_fail("getpeername(2)");
    return ipaddr((struct sockaddr*)&addr, fptr->mode & FMODE_NOREVLOOKUP);
}

/*
 * call-seq:
 *   ipsocket.recvfrom(maxlen)        => [mesg, ipaddr]
 *   ipsocket.recvfrom(maxlen, flags) => [mesg, ipaddr]
 *
 * Receives a message and return the message as a string and
 * an address which the message come from.
 *
 * _maxlen_ is the maximum number of bytes to receive.
 *
 * _flags_ should be a bitwise OR of Socket::MSG_* constants.
 *
 * ipaddr is same as IPSocket#{peeraddr,addr}.
 *
 *   u1 = UDPSocket.new
 *   u1.bind("127.0.0.1", 4913)
 *   u2 = UDPSocket.new
 *   u2.send "uuuu", 0, "127.0.0.1", 4913
 *   p u1.recvfrom(10) #=> ["uuuu", ["AF_INET", 33230, "localhost", "127.0.0.1"]]
 *   
 */
static VALUE
ip_recvfrom(int argc, VALUE *argv, VALUE sock)
{
    return s_recvfrom(sock, argc, argv, RECV_IP);
}

/*
 * call-seq:
 *   IPSocket.getaddress(host)        => ipaddress
 *
 * Lookups IP address of _host_.
 *
 *   IPSocket.getaddress("localhost")     #=> "127.0.0.1"
 *   IPSocket.getaddress("ip6-localhost") #=> "::1"
 *
 */
static VALUE
ip_s_getaddress(VALUE obj, VALUE host)
{
    struct sockaddr_storage addr;
    struct addrinfo *res = sock_addrinfo(host, Qnil, SOCK_STREAM, 0);

    /* just take the first one */
    memcpy(&addr, res->ai_addr, res->ai_addrlen);
    freeaddrinfo(res);

    return make_ipaddr((struct sockaddr*)&addr);
}

/*
 * call-seq:
 *   UDPSocket.new([address_family]) => socket
 *
 * Creates a new UDPSocket object.
 *
 * _address_family_ should be an integer, a string or a symbol:
 * Socket::AF_INET, "AF_INET", :INET, etc.
 *
 *   UDPSocket.new                   #=> #<UDPSocket:fd 3>
 *   UDPSocket.new(Socket::AF_INET6) #=> #<UDPSocket:fd 4>
 *
 */
static VALUE
udp_init(int argc, VALUE *argv, VALUE sock)
{
    VALUE arg;
    int family = AF_INET;
    int fd;

    rb_secure(3);
    if (rb_scan_args(argc, argv, "01", &arg) == 1) {
	family = family_arg(arg);
    }
    fd = ruby_socket(family, SOCK_DGRAM, 0);
    if (fd < 0) {
	rb_sys_fail("socket(2) - udp");
    }

    return init_sock(sock, fd);
}

struct udp_arg
{
    struct addrinfo *res;
    int fd;
};

static VALUE
udp_connect_internal(struct udp_arg *arg)
{
    int fd = arg->fd;
    struct addrinfo *res;

    for (res = arg->res; res; res = res->ai_next) {
	if (ruby_connect(fd, res->ai_addr, res->ai_addrlen, 0) >= 0) {
	    return Qtrue;
	}
    }
    return Qfalse;
}

/*
 * call-seq:
 *   udpsocket.connect(host, port) => 0
 *
 * Connects _udpsocket_ to _host_:_port_.
 *
 * This makes possible to send without destination address.
 *
 *   u1 = UDPSocket.new
 *   u1.bind("127.0.0.1", 4913)
 *   u2 = UDPSocket.new
 *   u2.connect("127.0.0.1", 4913)
 *   u2.send "uuuu", 0
 *   p u1.recvfrom(10) #=> ["uuuu", ["AF_INET", 33230, "localhost", "127.0.0.1"]]
 *
 */
static VALUE
udp_connect(VALUE sock, VALUE host, VALUE port)
{
    rb_io_t *fptr;
    struct udp_arg arg;
    VALUE ret;

    rb_secure(3);
    arg.res = sock_addrinfo(host, port, SOCK_DGRAM, 0);
    GetOpenFile(sock, fptr);
    arg.fd = fptr->fd;
    ret = rb_ensure(udp_connect_internal, (VALUE)&arg,
		    RUBY_METHOD_FUNC(freeaddrinfo), (VALUE)arg.res);
    if (!ret) rb_sys_fail("connect(2)");
    return INT2FIX(0);
}

/*
 * call-seq:
 *   udpsocket.bind(host, port) #=> 0
 *
 * Binds _udpsocket_ to _host_:_port_.
 *
 *   u1 = UDPSocket.new
 *   u1.bind("127.0.0.1", 4913)
 *   u1.send "message-to-self", 0, "127.0.0.1", 4913
 *   p u1.recvfrom(10) #=> ["message-to", ["AF_INET", 4913, "localhost", "127.0.0.1"]]
 *
 */
static VALUE
udp_bind(VALUE sock, VALUE host, VALUE port)
{
    rb_io_t *fptr;
    struct addrinfo *res0, *res;

    rb_secure(3);
    res0 = sock_addrinfo(host, port, SOCK_DGRAM, 0);
    GetOpenFile(sock, fptr);
    for (res = res0; res; res = res->ai_next) {
	if (bind(fptr->fd, res->ai_addr, res->ai_addrlen) < 0) {
	    continue;
	}
	freeaddrinfo(res0);
	return INT2FIX(0);
    }
    freeaddrinfo(res0);
    rb_sys_fail("bind(2)");
    return INT2FIX(0);
}

/*
 * call-seq:
 *   udpsocket.send(mesg, flags, host, port)  => numbytes_sent
 *   udpsocket.send(mesg, flags, sockaddr_to) => numbytes_sent
 *   udpsocket.send(mesg, flags)              => numbytes_sent
 *
 * Sends _mesg_ via _udpsocket_.
 * 
 * _flags_ should be a bitwise OR of Socket::MSG_* constants.
 *
 *   u1 = UDPSocket.new
 *   u1.bind("127.0.0.1", 4913)
 *
 *   u2 = UDPSocket.new
 *   u2.send "hi", 0, "127.0.0.1", 4913
 *
 *   mesg, addr = u1.recvfrom(10)
 *   u1.send mesg, 0, addr[3], addr[1]
 *
 *   p u2.recv(100) #=> "hi"
 *
 */
static VALUE
udp_send(int argc, VALUE *argv, VALUE sock)
{
    VALUE flags, host, port;
    rb_io_t *fptr;
    int n;
    struct addrinfo *res0, *res;
    struct send_arg arg;

    if (argc == 2 || argc == 3) {
	return bsock_send(argc, argv, sock);
    }
    rb_secure(4);
    rb_scan_args(argc, argv, "4", &arg.mesg, &flags, &host, &port);

    StringValue(arg.mesg);
    res0 = sock_addrinfo(host, port, SOCK_DGRAM, 0);
    GetOpenFile(sock, fptr);
    arg.fd = fptr->fd;
    arg.flags = NUM2INT(flags);
    for (res = res0; res; res = res->ai_next) {
      retry:
	arg.to = res->ai_addr;
	arg.tolen = res->ai_addrlen;
	rb_thread_fd_writable(arg.fd);
	n = (int)BLOCKING_REGION(sendto_blocking, &arg);
	if (n >= 0) {
	    freeaddrinfo(res0);
	    return INT2FIX(n);
	}
	if (rb_io_wait_writable(fptr->fd)) {
	    goto retry;
	}
    }
    freeaddrinfo(res0);
    rb_sys_fail("sendto(2)");
    return INT2FIX(n);
}

/*
 * call-seq:
 * 	udpsocket.recvfrom_nonblock(maxlen) => [mesg, sender_inet_addr]
 * 	udpsocket.recvfrom_nonblock(maxlen, flags) => [mesg, sender_inet_addr]
 * 
 * Receives up to _maxlen_ bytes from +udpsocket+ using recvfrom(2) after
 * O_NONBLOCK is set for the underlying file descriptor.
 * If _maxlen_ is ommitted, its default value is 65536.
 * _flags_ is zero or more of the +MSG_+ options.
 * The first element of the results, _mesg_, is the data received.
 * The second element, _sender_inet_addr_, is an array to represent the sender address.
 *
 * When recvfrom(2) returns 0,
 * Socket#recvfrom_nonblock returns an empty string as data.
 * It means an empty packet.
 * 
 * === Parameters
 * * +maxlen+ - the number of bytes to receive from the socket
 * * +flags+ - zero or more of the +MSG_+ options 
 * 
 * === Example
 * 	require 'socket'
 * 	s1 = UDPSocket.new
 * 	s1.bind("127.0.0.1", 0)
 * 	s2 = UDPSocket.new
 * 	s2.bind("127.0.0.1", 0)
 * 	s2.connect(*s1.addr.values_at(3,1))
 * 	s1.connect(*s2.addr.values_at(3,1))
 * 	s1.send "aaa", 0
 * 	IO.select([s2]) # emulate blocking recvfrom
 * 	p s2.recvfrom_nonblock(10)  #=> ["aaa", ["AF_INET", 33302, "localhost.localdomain", "127.0.0.1"]]
 *
 * Refer to Socket#recvfrom for the exceptions that may be thrown if the call
 * to _recvfrom_nonblock_ fails. 
 *
 * UDPSocket#recvfrom_nonblock may raise any error corresponding to recvfrom(2) failure,
 * including Errno::EWOULDBLOCK.
 *
 * === See
 * * Socket#recvfrom
 */
static VALUE
udp_recvfrom_nonblock(int argc, VALUE *argv, VALUE sock)
{
    return s_recvfrom_nonblock(sock, argc, argv, RECV_IP);
}

#ifdef HAVE_SYS_UN_H
/*
 * call-seq:
 *   UNIXSocket.new(path) => unixsocket
 *
 * Creates a new UNIX client socket connected to _path_.
 *
 *   s = UNIXSocket.new("/tmp/sock")
 *   s.send "hello", 0
 *   
 */
static VALUE
unix_init(VALUE sock, VALUE path)
{
    return init_unixsock(sock, path, 0);
}

static const char*
unixpath(struct sockaddr_un *sockaddr, socklen_t len)
{
    if (sockaddr->sun_path < (char*)sockaddr + len)
        return sockaddr->sun_path;
    else
        return "";
}

/*
 * call-seq:
 *   unixsocket.path => path
 *
 * Returns the path of the local address of unixsocket.
 *
 *   s = UNIXServer.new("/tmp/sock")
 *   p s.path #=> "/tmp/sock"
 *
 */
static VALUE
unix_path(VALUE sock)
{
    rb_io_t *fptr;

    GetOpenFile(sock, fptr);
    if (NIL_P(fptr->pathv)) {
	struct sockaddr_un addr;
	socklen_t len = sizeof(addr);
	if (getsockname(fptr->fd, (struct sockaddr*)&addr, &len) < 0)
	    rb_sys_fail(0);
	fptr->pathv = rb_obj_freeze(rb_str_new_cstr(unixpath(&addr, len)));
    }
    return rb_str_dup(fptr->pathv);
}

/*
 * call-seq:
 *   UNIXServer.new(path) => unixserver
 *
 * Creates a new UNIX server socket bound to _path_.
 *
 *   serv = UNIXServer.new("/tmp/sock")
 *   s = serv.accept
 *   p s.read
 */
static VALUE
unix_svr_init(VALUE sock, VALUE path)
{
    return init_unixsock(sock, path, 1);
}

/*
 * call-seq:
 *   unixsocket.recvfrom(maxlen [, flags]) => [mesg, unixaddress]
 *
 * Receives a message via _unixsocket_.
 *
 * _maxlen_ is the maximum number of bytes to receive.
 *
 * _flags_ should be a bitwise OR of Socket::MSG_* constants.
 *
 *   s1 = Socket.new(:UNIX, :DGRAM, 0)
 *   s1_ai = AddrInfo.unix("/tmp/sock1")
 *   s1.bind(s1_ai)
 *
 *   s2 = Socket.new(:UNIX, :DGRAM, 0)
 *   s2_ai = AddrInfo.unix("/tmp/sock2")
 *   s2.bind(s2_ai)
 *   s3 = UNIXSocket.for_fd(s2.fileno)
 *
 *   s1.send "a", 0, s2_ai
 *   p s3.recvfrom(10) #=> ["a", ["AF_UNIX", "/tmp/sock1"]]
 *
 */
static VALUE
unix_recvfrom(int argc, VALUE *argv, VALUE sock)
{
    return s_recvfrom(sock, argc, argv, RECV_UNIX);
}

#if defined(HAVE_ST_MSG_CONTROL) && defined(SCM_RIGHTS)
#define FD_PASSING_BY_MSG_CONTROL 1
#else
#define FD_PASSING_BY_MSG_CONTROL 0
#endif

#if defined(HAVE_ST_MSG_ACCRIGHTS)
#define FD_PASSING_BY_MSG_ACCRIGHTS 1
#else
#define FD_PASSING_BY_MSG_ACCRIGHTS 0
#endif

struct iomsg_arg {
    int fd;
    struct msghdr msg;
};

static VALUE
sendmsg_blocking(void *data)
{
    struct iomsg_arg *arg = data;
    return sendmsg(arg->fd, &arg->msg, 0);
}

/*
 * call-seq:
 *   unixsocket.send_io(io) => nil
 *
 * Sends _io_ as file descriptor passing.
 *
 *   s1, s2 = UNIXSocket.pair
 *
 *   s1.send_io STDOUT
 *   stdout = s2.recv_io
 *
 *   p STDOUT.fileno #=> 1
 *   p stdout.fileno #=> 6
 *
 *   stdout.puts "hello" # outputs "hello\n" to standard output.
 */
static VALUE
unix_send_io(VALUE sock, VALUE val)
{
#if defined(HAVE_SENDMSG) && (FD_PASSING_BY_MSG_CONTROL || FD_PASSING_BY_MSG_ACCRIGHTS)
    int fd;
    rb_io_t *fptr;
    struct iomsg_arg arg;
    struct iovec vec[1];
    char buf[1];

#if FD_PASSING_BY_MSG_CONTROL
    struct {
	struct cmsghdr hdr;
        char pad[8+sizeof(int)+8];
    } cmsg;
#endif

    if (rb_obj_is_kind_of(val, rb_cIO)) {
        rb_io_t *valfptr;
	GetOpenFile(val, valfptr);
	fd = valfptr->fd;
    }
    else if (FIXNUM_P(val)) {
        fd = FIX2INT(val);
    }
    else {
	rb_raise(rb_eTypeError, "neither IO nor file descriptor");
    }

    GetOpenFile(sock, fptr);

    arg.msg.msg_name = NULL;
    arg.msg.msg_namelen = 0;

    /* Linux and Solaris doesn't work if msg_iov is NULL. */
    buf[0] = '\0';
    vec[0].iov_base = buf;
    vec[0].iov_len = 1;
    arg.msg.msg_iov = vec;
    arg.msg.msg_iovlen = 1;

#if FD_PASSING_BY_MSG_CONTROL
    arg.msg.msg_control = (caddr_t)&cmsg;
    arg.msg.msg_controllen = CMSG_LEN(sizeof(int));
    arg.msg.msg_flags = 0;
    MEMZERO((char*)&cmsg, char, sizeof(cmsg));
    cmsg.hdr.cmsg_len = CMSG_LEN(sizeof(int));
    cmsg.hdr.cmsg_level = SOL_SOCKET;
    cmsg.hdr.cmsg_type = SCM_RIGHTS;
    *(int *)CMSG_DATA(&cmsg.hdr) = fd;
#else
    arg.msg.msg_accrights = (caddr_t)&fd;
    arg.msg.msg_accrightslen = sizeof(fd);
#endif

    arg.fd = fptr->fd;
    rb_thread_fd_writable(arg.fd);
    if ((int)BLOCKING_REGION(sendmsg_blocking, &arg) == -1)
	rb_sys_fail("sendmsg(2)");

    return Qnil;
#else
    rb_notimplement();
    return Qnil;		/* not reached */
#endif
}

static VALUE
recvmsg_blocking(void *data)
{
    struct iomsg_arg *arg = data;
    return recvmsg(arg->fd, &arg->msg, 0);
}

/*
 * call-seq:
 *   unixsocket.recv_io([klass [, mode]]) => io
 *
 *   UNIXServer.open("/tmp/sock") {|serv|
 *     UNIXSocket.open("/tmp/sock") {|c|  
 *       s = serv.accept
 *
 *       c.send_io STDOUT 
 *       stdout = s.recv_io 
 *
 *       p STDOUT.fileno #=> 1
 *       p stdout.fileno #=> 7
 *
 *       stdout.puts "hello" # outputs "hello\n" to standard output.
 *     }
 *   }
 *
 */
static VALUE
unix_recv_io(int argc, VALUE *argv, VALUE sock)
{
#if defined(HAVE_RECVMSG) && (FD_PASSING_BY_MSG_CONTROL || FD_PASSING_BY_MSG_ACCRIGHTS)
    VALUE klass, mode;
    rb_io_t *fptr;
    struct iomsg_arg arg;
    struct iovec vec[2];
    char buf[1];

    int fd;
#if FD_PASSING_BY_MSG_CONTROL
    struct {
	struct cmsghdr hdr;
        char pad[8+sizeof(int)+8];
    } cmsg;
#endif

    rb_scan_args(argc, argv, "02", &klass, &mode);
    if (argc == 0)
	klass = rb_cIO;
    if (argc <= 1)
	mode = Qnil;

    GetOpenFile(sock, fptr);

    arg.msg.msg_name = NULL;
    arg.msg.msg_namelen = 0;

    vec[0].iov_base = buf;
    vec[0].iov_len = sizeof(buf);
    arg.msg.msg_iov = vec;
    arg.msg.msg_iovlen = 1;

#if FD_PASSING_BY_MSG_CONTROL
    arg.msg.msg_control = (caddr_t)&cmsg;
    arg.msg.msg_controllen = CMSG_SPACE(sizeof(int));
    arg.msg.msg_flags = 0;
    cmsg.hdr.cmsg_len = CMSG_LEN(sizeof(int));
    cmsg.hdr.cmsg_level = SOL_SOCKET;
    cmsg.hdr.cmsg_type = SCM_RIGHTS;
    *(int *)CMSG_DATA(&cmsg.hdr) = -1;
#else
    arg.msg.msg_accrights = (caddr_t)&fd;
    arg.msg.msg_accrightslen = sizeof(fd);
    fd = -1;
#endif

    arg.fd = fptr->fd;
    rb_thread_wait_fd(arg.fd);
    if ((int)BLOCKING_REGION(recvmsg_blocking, &arg) == -1)
	rb_sys_fail("recvmsg(2)");

#if FD_PASSING_BY_MSG_CONTROL
    if (arg.msg.msg_controllen < CMSG_LEN(sizeof(int))) {
	rb_raise(rb_eSocket,
		 "file descriptor was not passed (msg_controllen=%d smaller than CMSG_LEN(sizeof(int))=%d)",
		 (int)arg.msg.msg_controllen, (int)CMSG_LEN(sizeof(int)));
    }
    if (CMSG_SPACE(sizeof(int)) < arg.msg.msg_controllen) {
	rb_raise(rb_eSocket,
		 "file descriptor was not passed (msg_controllen=%d bigger than CMSG_SPACE(sizeof(int))=%d)",
		 (int)arg.msg.msg_controllen, (int)CMSG_SPACE(sizeof(int)));
    }
    if (cmsg.hdr.cmsg_len != CMSG_LEN(sizeof(int))) {
	rb_raise(rb_eSocket,
		 "file descriptor was not passed (cmsg_len=%d, %d expected)",
		 (int)cmsg.hdr.cmsg_len, (int)CMSG_LEN(sizeof(int)));
    }
    if (cmsg.hdr.cmsg_level != SOL_SOCKET) {
	rb_raise(rb_eSocket,
		 "file descriptor was not passed (cmsg_level=%d, %d expected)",
		 cmsg.hdr.cmsg_level, SOL_SOCKET);
    }
    if (cmsg.hdr.cmsg_type != SCM_RIGHTS) {
	rb_raise(rb_eSocket,
		 "file descriptor was not passed (cmsg_type=%d, %d expected)",
		 cmsg.hdr.cmsg_type, SCM_RIGHTS);
    }
#else
    if (arg.msg.msg_accrightslen != sizeof(fd)) {
	rb_raise(rb_eSocket,
		 "file descriptor was not passed (accrightslen) : %d != %d",
		 arg.msg.msg_accrightslen, (int)sizeof(fd));
    }
#endif

#if FD_PASSING_BY_MSG_CONTROL
    fd = *(int *)CMSG_DATA(&cmsg.hdr);
#endif

    if (klass == Qnil)
	return INT2FIX(fd);
    else {
	ID for_fd;
	int ff_argc;
	VALUE ff_argv[2];
	CONST_ID(for_fd, "for_fd");
	ff_argc = mode == Qnil ? 1 : 2;
	ff_argv[0] = INT2FIX(fd);
	ff_argv[1] = mode;
        return rb_funcall2(klass, for_fd, ff_argc, ff_argv);
    }
#else
    rb_notimplement();
    return Qnil;		/* not reached */
#endif
}

/*
 * call-seq:
 *   unixserver.accept => unixsocket
 *
 * Accepts a new connection.
 * It returns new UNIXSocket object.
 *
 *   UNIXServer.open("/tmp/sock") {|serv|
 *     UNIXSocket.open("/tmp/sock") {|c|
 *       s = serv.accept
 *       s.puts "hi"
 *       s.close
 *       p c.read #=> "hi\n"
 *     }
 *   }
 *
 */
static VALUE
unix_accept(VALUE sock)
{
    rb_io_t *fptr;
    struct sockaddr_un from;
    socklen_t fromlen;

    GetOpenFile(sock, fptr);
    fromlen = sizeof(struct sockaddr_un);
    return s_accept(rb_cUNIXSocket, fptr->fd,
		    (struct sockaddr*)&from, &fromlen);
}

/*
 * call-seq:
 * 	unixserver.accept_nonblock => unixsocket
 * 
 * Accepts an incoming connection using accept(2) after
 * O_NONBLOCK is set for the underlying file descriptor.
 * It returns an accepted UNIXSocket for the incoming connection.
 * 
 * === Example
 * 	require 'socket'
 * 	serv = UNIXServer.new("/tmp/sock")
 * 	begin # emulate blocking accept
 * 	  sock = serv.accept_nonblock
 * 	rescue Errno::EAGAIN, Errno::EWOULDBLOCK, Errno::ECONNABORTED, Errno::EPROTO, Errno::EINTR
 * 	  IO.select([serv])
 * 	  retry
 * 	end
 * 	# sock is an accepted socket.
 * 
 * Refer to Socket#accept for the exceptions that may be thrown if the call
 * to UNIXServer#accept_nonblock fails. 
 *
 * UNIXServer#accept_nonblock may raise any error corresponding to accept(2) failure,
 * including Errno::EWOULDBLOCK.
 * 
 * === See
 * * UNIXServer#accept
 * * Socket#accept
 */
static VALUE
unix_accept_nonblock(VALUE sock)
{
    rb_io_t *fptr;
    struct sockaddr_un from;
    socklen_t fromlen;

    GetOpenFile(sock, fptr);
    fromlen = sizeof(from);
    return s_accept_nonblock(rb_cUNIXSocket, fptr,
			     (struct sockaddr *)&from, &fromlen);
}

/*
 * call-seq:
 *   unixserver.sysaccept => file_descriptor
 *
 * Accepts a new connection.
 * It returns the new file descriptor which is an integer.
 *
 *   UNIXServer.open("/tmp/sock") {|serv|
 *     UNIXSocket.open("/tmp/sock") {|c|
 *       fd = serv.sysaccept
 *       s = IO.new(fd)
 *       s.puts "hi"
 *       s.close 
 *       p c.read #=> "hi\n"
 *     }
 *   }
 *
 */
static VALUE
unix_sysaccept(VALUE sock)
{
    rb_io_t *fptr;
    struct sockaddr_un from;
    socklen_t fromlen;

    GetOpenFile(sock, fptr);
    fromlen = sizeof(struct sockaddr_un);
    return s_accept(0, fptr->fd, (struct sockaddr*)&from, &fromlen);
}

static VALUE
unixaddr(struct sockaddr_un *sockaddr, socklen_t len)
{
    return rb_assoc_new(rb_str_new2("AF_UNIX"),
                        rb_str_new2(unixpath(sockaddr, len)));
}

/*
 * call-seq:
 *   unixsocket.addr => [address_family, unix_path]
 *
 * Returns the local address as an array which contains
 * address_family and unix_path.
 *
 * Example
 *   serv = UNIXServer.new("/tmp/sock")
 *   p serv.addr #=> ["AF_UNIX", "/tmp/sock"]
 */
static VALUE
unix_addr(VALUE sock)
{
    rb_io_t *fptr;
    struct sockaddr_un addr;
    socklen_t len = sizeof addr;

    GetOpenFile(sock, fptr);

    if (getsockname(fptr->fd, (struct sockaddr*)&addr, &len) < 0)
	rb_sys_fail("getsockname(2)");
    return unixaddr(&addr, len);
}

/*
 * call-seq:
 *   unixsocket.peeraddr => [address_family, unix_path]
 *
 * Returns the remote address as an array which contains
 * address_family and unix_path.
 *
 * Example
 *   serv = UNIXServer.new("/tmp/sock")
 *   c = UNIXSocket.new("/tmp/sock")
 *   p c.peeraddr #=> ["AF_UNIX", "/tmp/sock"]
 */
static VALUE
unix_peeraddr(VALUE sock)
{
    rb_io_t *fptr;
    struct sockaddr_un addr;
    socklen_t len = sizeof addr;

    GetOpenFile(sock, fptr);

    if (getpeername(fptr->fd, (struct sockaddr*)&addr, &len) < 0)
	rb_sys_fail("getpeername(2)");
    return unixaddr(&addr, len);
}
#endif

static void
setup_domain_and_type(VALUE domain, int *dv, VALUE type, int *tv)
{
    *dv = family_arg(domain);
    *tv = socktype_arg(type);
}

/*
 * call-seq:
 *   Socket.new(domain, socktype, protocol) => socket
 *
 * Creates a new socket object.
 *
 * _domain_ should be a communications domain such as: :INET, :INET6, :UNIX, etc.
 *
 * _socktype_ should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.
 *
 * _protocol_ should be a protocol defined in the domain.
 * 0 is default protocol for the domain.
 *
 *   Socket.new(:INET, :STREAM, 0) # TCP socket
 *   Socket.new(:INET, :DGRAM, 0)  # UDP socket
 *   Socket.new(:UNIX, :STREAM, 0) # UNIX stream socket
 *   Socket.new(:UNIX, :DGRAM, 0)  # UNIX datagram socket
 */
static VALUE
sock_initialize(VALUE sock, VALUE domain, VALUE type, VALUE protocol)
{
    int fd;
    int d, t;

    rb_secure(3);
    setup_domain_and_type(domain, &d, type, &t);
    fd = ruby_socket(d, t, NUM2INT(protocol));
    if (fd < 0) rb_sys_fail("socket(2)");

    return init_sock(sock, fd);
}

#if defined HAVE_SOCKETPAIR
static VALUE
io_call_close(VALUE io)
{
    return rb_funcall(io, rb_intern("close"), 0, 0);
}

static VALUE
io_close(VALUE io)
{
    return rb_rescue(io_call_close, io, 0, 0);
}

static VALUE
pair_yield(VALUE pair)
{
    return rb_ensure(rb_yield, pair, io_close, rb_ary_entry(pair, 1));
}
#endif

/*
 * call-seq:
 *   Socket.pair(domain, type, protocol)       => [socket1, socket2]
 *   Socket.socketpair(domain, type, protocol) => [socket1, socket2]
 *
 * Creates a pair of sockets connected each other.
 *
 * _domain_ should be a communications domain such as: :INET, :INET6, :UNIX, etc.
 *
 * _socktype_ should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.
 *
 * _protocol_ should be a protocol defined in the domain.
 * 0 is default protocol for the domain.
 *
 *   s1, s2 = Socket.pair(:UNIX, :DGRAM, 0)
 *   s1.send "a", 0
 *   s1.send "b", 0
 *   p s2.recv(10) #=> "a"
 *   p s2.recv(10) #=> "b"
 *
 */
static VALUE
sock_s_socketpair(VALUE klass, VALUE domain, VALUE type, VALUE protocol)
{
#if defined HAVE_SOCKETPAIR
    int d, t, p, sp[2];
    int ret;
    VALUE s1, s2, r;

    setup_domain_and_type(domain, &d, type, &t);
    p = NUM2INT(protocol);
    ret = socketpair(d, t, p, sp);
    if (ret < 0 && (errno == EMFILE || errno == ENFILE)) {
        rb_gc();
        ret = socketpair(d, t, p, sp);
    }
    if (ret < 0) {
	rb_sys_fail("socketpair(2)");
    }

    s1 = init_sock(rb_obj_alloc(klass), sp[0]);
    s2 = init_sock(rb_obj_alloc(klass), sp[1]);
    r = rb_assoc_new(s1, s2);
    if (rb_block_given_p()) {
        return rb_ensure(pair_yield, r, io_close, s1);
    }
    return r;
#else
    rb_notimplement();
#endif
}

#ifdef HAVE_SYS_UN_H
/*
 * call-seq:
 *   UNIXSocket.pair([type [, protocol]])       => [unixsocket1, unixsocket2]
 *   UNIXSocket.socketpair([type [, protocol]]) => [unixsocket1, unixsocket2]
 *
 * Creates a pair of sockets connected each other.
 *
 * _socktype_ should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.
 *
 * _protocol_ should be a protocol defined in the domain.
 * 0 is default protocol for the domain.
 *
 *   s1, s2 = UNIXSocket.pair
 *   s1.send "a", 0
 *   s1.send "b", 0
 *   p s2.recv(10) #=> "ab"
 *
 */
static VALUE
unix_s_socketpair(int argc, VALUE *argv, VALUE klass)
{
    VALUE domain, type, protocol;
    domain = INT2FIX(PF_UNIX);

    rb_scan_args(argc, argv, "02", &type, &protocol);
    if (argc == 0)
	type = INT2FIX(SOCK_STREAM);
    if (argc <= 1)
	protocol = INT2FIX(0);

    return sock_s_socketpair(klass, domain, type, protocol);
}
#endif

/*
 * call-seq:
 * 	socket.connect(server_sockaddr) => 0
 * 
 * Requests a connection to be made on the given +server_sockaddr+. Returns 0 if
 * successful, otherwise an exception is raised.
 *  
 * === Parameter
 * * +server_sockaddr+ - the +struct+ sockaddr contained in a string
 * 
 * === Example:
 * 	# Pull down Google's web page
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
 * 	sockaddr = Socket.pack_sockaddr_in( 80, 'www.google.com' )
 * 	socket.connect( sockaddr )
 * 	socket.write( "GET / HTTP/1.0\r\n\r\n" )
 * 	results = socket.read 
 * 
 * === Unix-based Exceptions
 * On unix-based systems the following system exceptions may be raised if 
 * the call to _connect_ fails:
 * * Errno::EACCES - search permission is denied for a component of the prefix
 *   path or write access to the +socket+ is denided
 * * Errno::EADDRINUSE - the _sockaddr_ is already in use
 * * Errno::EADDRNOTAVAIL - the specified _sockaddr_ is not available from the
 *   local machine
 * * Errno::EAFNOSUPPORT - the specified _sockaddr_ is not a valid address for 
 *   the address family of the specified +socket+
 * * Errno::EALREADY - a connection is already in progress for the specified
 *   socket
 * * Errno::EBADF - the +socket+ is not a valid file descriptor
 * * Errno::ECONNREFUSED - the target _sockaddr_ was not listening for connections
 *   refused the connection request
 * * Errno::ECONNRESET - the remote host reset the connection request
 * * Errno::EFAULT - the _sockaddr_ cannot be accessed
 * * Errno::EHOSTUNREACH - the destination host cannot be reached (probably 
 *   because the host is down or a remote router cannot reach it)
 * * Errno::EINPROGRESS - the O_NONBLOCK is set for the +socket+ and the
 *   connection cnanot be immediately established; the connection will be
 *   established asynchronously
 * * Errno::EINTR - the attempt to establish the connection was interrupted by
 *   delivery of a signal that was caught; the connection will be established
 *   asynchronously
 * * Errno::EISCONN - the specified +socket+ is already connected
 * * Errno::EINVAL - the address length used for the _sockaddr_ is not a valid
 *   length for the address family or there is an invalid family in _sockaddr_ 
 * * Errno::ENAMETOOLONG - the pathname resolved had a length which exceeded
 *   PATH_MAX
 * * Errno::ENETDOWN - the local interface used to reach the destination is down
 * * Errno::ENETUNREACH - no route to the network is present
 * * Errno::ENOBUFS - no buffer space is available
 * * Errno::ENOSR - there were insufficient STREAMS resources available to 
 *   complete the operation
 * * Errno::ENOTSOCK - the +socket+ argument does not refer to a socket
 * * Errno::EOPNOTSUPP - the calling +socket+ is listening and cannot be connected
 * * Errno::EPROTOTYPE - the _sockaddr_ has a different type than the socket 
 *   bound to the specified peer address
 * * Errno::ETIMEDOUT - the attempt to connect time out before a connection
 *   was made.
 * 
 * On unix-based systems if the address family of the calling +socket+ is
 * AF_UNIX the follow exceptions may be raised if the call to _connect_
 * fails:
 * * Errno::EIO - an i/o error occured while reading from or writing to the 
 *   file system
 * * Errno::ELOOP - too many symbolic links were encountered in translating
 *   the pathname in _sockaddr_
 * * Errno::ENAMETOOLLONG - a component of a pathname exceeded NAME_MAX 
 *   characters, or an entired pathname exceeded PATH_MAX characters
 * * Errno::ENOENT - a component of the pathname does not name an existing file
 *   or the pathname is an empty string
 * * Errno::ENOTDIR - a component of the path prefix of the pathname in _sockaddr_
 *   is not a directory 
 * 
 * === Windows Exceptions
 * On Windows systems the following system exceptions may be raised if 
 * the call to _connect_ fails:
 * * Errno::ENETDOWN - the network is down
 * * Errno::EADDRINUSE - the socket's local address is already in use
 * * Errno::EINTR - the socket was cancelled
 * * Errno::EINPROGRESS - a blocking socket is in progress or the service provider
 *   is still processing a callback function. Or a nonblocking connect call is 
 *   in progress on the +socket+.
 * * Errno::EALREADY - see Errno::EINVAL
 * * Errno::EADDRNOTAVAIL - the remote address is not a valid address, such as 
 *   ADDR_ANY TODO check ADDRANY TO INADDR_ANY
 * * Errno::EAFNOSUPPORT - addresses in the specified family cannot be used with
 *   with this +socket+
 * * Errno::ECONNREFUSED - the target _sockaddr_ was not listening for connections
 *   refused the connection request
 * * Errno::EFAULT - the socket's internal address or address length parameter
 *   is too small or is not a valid part of the user space address
 * * Errno::EINVAL - the +socket+ is a listening socket
 * * Errno::EISCONN - the +socket+ is already connected
 * * Errno::ENETUNREACH - the network cannot be reached from this host at this time
 * * Errno::EHOSTUNREACH - no route to the network is present
 * * Errno::ENOBUFS - no buffer space is available
 * * Errno::ENOTSOCK - the +socket+ argument does not refer to a socket
 * * Errno::ETIMEDOUT - the attempt to connect time out before a connection
 *   was made.
 * * Errno::EWOULDBLOCK - the socket is marked as nonblocking and the 
 *   connection cannot be completed immediately
 * * Errno::EACCES - the attempt to connect the datagram socket to the 
 *   broadcast address failed
 * 
 * === See
 * * connect manual pages on unix-based systems
 * * connect function in Microsoft's Winsock functions reference
 */
static VALUE
sock_connect(VALUE sock, VALUE addr)
{
    rb_io_t *fptr;
    int fd, n;

    SockAddrStringValue(addr);
    addr = rb_str_new4(addr);
    GetOpenFile(sock, fptr);
    fd = fptr->fd;
    n = ruby_connect(fd, (struct sockaddr*)RSTRING_PTR(addr), RSTRING_LEN(addr), 0);
    if (n < 0) {
	rb_sys_fail("connect(2)");
    }

    return INT2FIX(n);
}

/*
 * call-seq:
 * 	socket.connect_nonblock(server_sockaddr) => 0
 * 
 * Requests a connection to be made on the given +server_sockaddr+ after
 * O_NONBLOCK is set for the underlying file descriptor.
 * Returns 0 if successful, otherwise an exception is raised.
 *  
 * === Parameter
 * * +server_sockaddr+ - the +struct+ sockaddr contained in a string
 * 
 * === Example:
 * 	# Pull down Google's web page
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new(AF_INET, SOCK_STREAM, 0)
 * 	sockaddr = Socket.sockaddr_in(80, 'www.google.com')
 * 	begin # emulate blocking connect
 * 	  socket.connect_nonblock(sockaddr)
 * 	rescue Errno::EINPROGRESS
 * 	  IO.select(nil, [socket])
 * 	  begin
 * 	    socket.connect_nonblock(sockaddr)
 * 	  rescue Errno::EISCONN
 * 	  end
 * 	end
 * 	socket.write("GET / HTTP/1.0\r\n\r\n")
 * 	results = socket.read 
 * 
 * Refer to Socket#connect for the exceptions that may be thrown if the call
 * to _connect_nonblock_ fails. 
 *
 * Socket#connect_nonblock may raise any error corresponding to connect(2) failure,
 * including Errno::EINPROGRESS.
 *
 * === See
 * * Socket#connect
 */
static VALUE
sock_connect_nonblock(VALUE sock, VALUE addr)
{
    rb_io_t *fptr;
    int n;

    SockAddrStringValue(addr);
    addr = rb_str_new4(addr);
    GetOpenFile(sock, fptr);
    rb_io_set_nonblock(fptr);
    n = connect(fptr->fd, (struct sockaddr*)RSTRING_PTR(addr), RSTRING_LEN(addr));
    if (n < 0) {
	rb_sys_fail("connect(2)");
    }

    return INT2FIX(n);
}

/*
 * call-seq:
 * 	socket.bind(server_sockaddr) => 0
 * 
 * Binds to the given +struct+ sockaddr.
 * 
 * === Parameter
 * * +server_sockaddr+ - the +struct+ sockaddr contained in a string
 *
 * === Example
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
 * 	sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
 * 	socket.bind( sockaddr )
 *  
 * === Unix-based Exceptions
 * On unix-based based systems the following system exceptions may be raised if 
 * the call to _bind_ fails:
 * * Errno::EACCES - the specified _sockaddr_ is protected and the current
 *   user does not have permission to bind to it
 * * Errno::EADDRINUSE - the specified _sockaddr_ is already in use
 * * Errno::EADDRNOTAVAIL - the specified _sockaddr_ is not available from the
 *   local machine
 * * Errno::EAFNOSUPPORT - the specified _sockaddr_ isnot a valid address for
 *   the family of the calling +socket+
 * * Errno::EBADF - the _sockaddr_ specified is not a valid file descriptor
 * * Errno::EFAULT - the _sockaddr_ argument cannot be accessed
 * * Errno::EINVAL - the +socket+ is already bound to an address, and the 
 *   protocol does not support binding to the new _sockaddr_ or the +socket+
 *   has been shut down.
 * * Errno::EINVAL - the address length is not a valid length for the address
 *   family
 * * Errno::ENAMETOOLONG - the pathname resolved had a length which exceeded
 *   PATH_MAX
 * * Errno::ENOBUFS - no buffer space is available
 * * Errno::ENOSR - there were insufficient STREAMS resources available to 
 *   complete the operation
 * * Errno::ENOTSOCK - the +socket+ does not refer to a socket
 * * Errno::EOPNOTSUPP - the socket type of the +socket+ does not support 
 *   binding to an address
 * 
 * On unix-based based systems if the address family of the calling +socket+ is
 * Socket::AF_UNIX the follow exceptions may be raised if the call to _bind_
 * fails:
 * * Errno::EACCES - search permission is denied for a component of the prefix
 *   path or write access to the +socket+ is denided
 * * Errno::EDESTADDRREQ - the _sockaddr_ argument is a null pointer
 * * Errno::EISDIR - same as Errno::EDESTADDRREQ
 * * Errno::EIO - an i/o error occurred
 * * Errno::ELOOP - too many symbolic links were encountered in translating
 *   the pathname in _sockaddr_
 * * Errno::ENAMETOOLLONG - a component of a pathname exceeded NAME_MAX 
 *   characters, or an entired pathname exceeded PATH_MAX characters
 * * Errno::ENOENT - a component of the pathname does not name an existing file
 *   or the pathname is an empty string
 * * Errno::ENOTDIR - a component of the path prefix of the pathname in _sockaddr_
 *   is not a directory
 * * Errno::EROFS - the name would reside on a read only filesystem
 * 
 * === Windows Exceptions
 * On Windows systems the following system exceptions may be raised if 
 * the call to _bind_ fails:
 * * Errno::ENETDOWN-- the network is down
 * * Errno::EACCES - the attempt to connect the datagram socket to the 
 *   broadcast address failed
 * * Errno::EADDRINUSE - the socket's local address is already in use
 * * Errno::EADDRNOTAVAIL - the specified address is not a valid address for this
 *   computer
 * * Errno::EFAULT - the socket's internal address or address length parameter
 *   is too small or is not a valid part of the user space addressed
 * * Errno::EINVAL - the +socket+ is already bound to an address
 * * Errno::ENOBUFS - no buffer space is available
 * * Errno::ENOTSOCK - the +socket+ argument does not refer to a socket
 * 
 * === See
 * * bind manual pages on unix-based systems
 * * bind function in Microsoft's Winsock functions reference
 */ 
static VALUE
sock_bind(VALUE sock, VALUE addr)
{
    rb_io_t *fptr;

    SockAddrStringValue(addr);
    GetOpenFile(sock, fptr);
    if (bind(fptr->fd, (struct sockaddr*)RSTRING_PTR(addr), RSTRING_LEN(addr)) < 0)
	rb_sys_fail("bind(2)");

    return INT2FIX(0);
}

/*
 * call-seq:
 * 	socket.listen( int ) => 0
 * 
 * Listens for connections, using the specified +int+ as the backlog. A call
 * to _listen_ only applies if the +socket+ is of type SOCK_STREAM or 
 * SOCK_SEQPACKET.
 * 
 * === Parameter
 * * +backlog+ - the maximum length of the queue for pending connections.
 * 
 * === Example 1
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
 * 	sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
 * 	socket.bind( sockaddr )
 * 	socket.listen( 5 )
 * 
 * === Example 2 (listening on an arbitary port, unix-based systems only):
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
 * 	socket.listen( 1 )
 * 
 * === Unix-based Exceptions
 * On unix based systems the above will work because a new +sockaddr+ struct
 * is created on the address ADDR_ANY, for an arbitrary port number as handed
 * off by the kernel. It will not work on Windows, because Windows requires that
 * the +socket+ is bound by calling _bind_ before it can _listen_.
 * 
 * If the _backlog_ amount exceeds the implementation-dependent maximum
 * queue length, the implementation's maximum queue length will be used.
 * 
 * On unix-based based systems the following system exceptions may be raised if the
 * call to _listen_ fails:
 * * Errno::EBADF - the _socket_ argument is not a valid file descriptor
 * * Errno::EDESTADDRREQ - the _socket_ is not bound to a local address, and 
 *   the protocol does not support listening on an unbound socket
 * * Errno::EINVAL - the _socket_ is already connected
 * * Errno::ENOTSOCK - the _socket_ argument does not refer to a socket
 * * Errno::EOPNOTSUPP - the _socket_ protocol does not support listen
 * * Errno::EACCES - the calling process does not have approriate privileges
 * * Errno::EINVAL - the _socket_ has been shut down
 * * Errno::ENOBUFS - insufficient resources are available in the system to 
 *   complete the call
 * 
 * === Windows Exceptions
 * On Windows systems the following system exceptions may be raised if 
 * the call to _listen_ fails:
 * * Errno::ENETDOWN - the network is down
 * * Errno::EADDRINUSE - the socket's local address is already in use. This 
 *   usually occurs during the execution of _bind_ but could be delayed
 *   if the call to _bind_ was to a partially wildcard address (involving
 *   ADDR_ANY) and if a specific address needs to be commmitted at the 
 *   time of the call to _listen_
 * * Errno::EINPROGRESS - a Windows Sockets 1.1 call is in progress or the
 *   service provider is still processing a callback function
 * * Errno::EINVAL - the +socket+ has not been bound with a call to _bind_.
 * * Errno::EISCONN - the +socket+ is already connected
 * * Errno::EMFILE - no more socket descriptors are available
 * * Errno::ENOBUFS - no buffer space is available
 * * Errno::ENOTSOC - +socket+ is not a socket
 * * Errno::EOPNOTSUPP - the referenced +socket+ is not a type that supports
 *   the _listen_ method
 * 
 * === See
 * * listen manual pages on unix-based systems
 * * listen function in Microsoft's Winsock functions reference
 */
static VALUE
sock_listen(VALUE sock, VALUE log)
{
    rb_io_t *fptr;
    int backlog;

    rb_secure(4);
    backlog = NUM2INT(log);
    GetOpenFile(sock, fptr);
    if (listen(fptr->fd, backlog) < 0)
	rb_sys_fail("listen(2)");

    return INT2FIX(0);
}

/*
 * call-seq:
 * 	socket.recvfrom(maxlen) => [mesg, sender_sockaddr]
 * 	socket.recvfrom(maxlen, flags) => [mesg, sender_sockaddr]
 * 
 * Receives up to _maxlen_ bytes from +socket+. _flags_ is zero or more
 * of the +MSG_+ options. The first element of the results, _mesg_, is the data
 * received. The second element, _sender_sockaddr_, contains protocol-specific information
 * on the sender.
 * 
 * === Parameters
 * * +maxlen+ - the number of bytes to receive from the socket
 * * +flags+ - zero or more of the +MSG_+ options 
 * 
 * === Example
 * 	# In one file, start this first
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
 * 	sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
 * 	socket.bind( sockaddr )
 * 	socket.listen( 5 )
 * 	client, client_sockaddr = socket.accept
 * 	data = client.recvfrom( 20 )[0].chomp
 * 	puts "I only received 20 bytes '#{data}'"
 * 	sleep 1
 * 	socket.close
 * 
 * 	# In another file, start this second
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
 * 	sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
 * 	socket.connect( sockaddr )
 * 	socket.puts "Watch this get cut short!"
 * 	socket.close 
 * 
 * === Unix-based Exceptions
 * On unix-based based systems the following system exceptions may be raised if the
 * call to _recvfrom_ fails:
 * * Errno::EAGAIN - the +socket+ file descriptor is marked as O_NONBLOCK and no
 *   data is waiting to be received; or MSG_OOB is set and no out-of-band data
 *   is available and either the +socket+ file descriptor is marked as 
 *   O_NONBLOCK or the +socket+ does not support blocking to wait for 
 *   out-of-band-data
 * * Errno::EWOULDBLOCK - see Errno::EAGAIN
 * * Errno::EBADF - the +socket+ is not a valid file descriptor
 * * Errno::ECONNRESET - a connection was forcibly closed by a peer
 * * Errno::EFAULT - the socket's internal buffer, address or address length 
 *   cannot be accessed or written
 * * Errno::EINTR - a signal interupted _recvfrom_ before any data was available
 * * Errno::EINVAL - the MSG_OOB flag is set and no out-of-band data is available
 * * Errno::EIO - an i/o error occurred while reading from or writing to the 
 *   filesystem
 * * Errno::ENOBUFS - insufficient resources were available in the system to 
 *   perform the operation
 * * Errno::ENOMEM - insufficient memory was available to fulfill the request
 * * Errno::ENOSR - there were insufficient STREAMS resources available to 
 *   complete the operation
 * * Errno::ENOTCONN - a receive is attempted on a connection-mode socket that
 *   is not connected
 * * Errno::ENOTSOCK - the +socket+ does not refer to a socket
 * * Errno::EOPNOTSUPP - the specified flags are not supported for this socket type
 * * Errno::ETIMEDOUT - the connection timed out during connection establishment
 *   or due to a transmission timeout on an active connection
 * 
 * === Windows Exceptions
 * On Windows systems the following system exceptions may be raised if 
 * the call to _recvfrom_ fails:
 * * Errno::ENETDOWN - the network is down
 * * Errno::EFAULT - the internal buffer and from parameters on +socket+ are not
 *   part of the user address space, or the internal fromlen parameter is
 *   too small to accomodate the peer address
 * * Errno::EINTR - the (blocking) call was cancelled by an internal call to
 *   the WinSock function WSACancelBlockingCall
 * * Errno::EINPROGRESS - a blocking Windows Sockets 1.1 call is in progress or 
 *   the service provider is still processing a callback function
 * * Errno::EINVAL - +socket+ has not been bound with a call to _bind_, or an
 *   unknown flag was specified, or MSG_OOB was specified for a socket with
 *   SO_OOBINLINE enabled, or (for byte stream-style sockets only) the internal
 *   len parameter on +socket+ was zero or negative
 * * Errno::EISCONN - +socket+ is already connected. The call to _recvfrom_ is
 *   not permitted with a connected socket on a socket that is connetion 
 *   oriented or connectionless.
 * * Errno::ENETRESET - the connection has been broken due to the keep-alive 
 *   activity detecting a failure while the operation was in progress.
 * * Errno::EOPNOTSUPP - MSG_OOB was specified, but +socket+ is not stream-style
 *   such as type SOCK_STREAM. OOB data is not supported in the communication
 *   domain associated with +socket+, or +socket+ is unidirectional and 
 *   supports only send operations
 * * Errno::ESHUTDOWN - +socket+ has been shutdown. It is not possible to 
 *   call _recvfrom_ on a socket after _shutdown_ has been invoked.
 * * Errno::EWOULDBLOCK - +socket+ is marked as nonblocking and a  call to 
 *   _recvfrom_ would block.
 * * Errno::EMSGSIZE - the message was too large to fit into the specified buffer
 *   and was truncated.
 * * Errno::ETIMEDOUT - the connection has been dropped, because of a network
 *   failure or because the system on the other end went down without
 *   notice
 * * Errno::ECONNRESET - the virtual circuit was reset by the remote side 
 *   executing a hard or abortive close. The application should close the
 *   socket; it is no longer usable. On a UDP-datagram socket this error
 *   indicates a previous send operation resulted in an ICMP Port Unreachable
 *   message.
 */
static VALUE
sock_recvfrom(int argc, VALUE *argv, VALUE sock)
{
    return s_recvfrom(sock, argc, argv, RECV_SOCKET);
}

/*
 * call-seq:
 * 	socket.recvfrom_nonblock(maxlen) => [mesg, sender_sockaddr]
 * 	socket.recvfrom_nonblock(maxlen, flags) => [mesg, sender_sockaddr]
 * 
 * Receives up to _maxlen_ bytes from +socket+ using recvfrom(2) after
 * O_NONBLOCK is set for the underlying file descriptor.
 * _flags_ is zero or more of the +MSG_+ options.
 * The first element of the results, _mesg_, is the data received.
 * The second element, _sender_sockaddr_, contains protocol-specific information
 * on the sender.
 *
 * When recvfrom(2) returns 0, Socket#recvfrom_nonblock returns
 * an empty string as data.
 * The meaning depends on the socket: EOF on TCP, empty packet on UDP, etc.
 * 
 * === Parameters
 * * +maxlen+ - the number of bytes to receive from the socket
 * * +flags+ - zero or more of the +MSG_+ options 
 * 
 * === Example
 * 	# In one file, start this first
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new(AF_INET, SOCK_STREAM, 0)
 * 	sockaddr = Socket.sockaddr_in(2200, 'localhost')
 * 	socket.bind(sockaddr)
 * 	socket.listen(5)
 * 	client, client_sockaddr = socket.accept
 * 	begin # emulate blocking recvfrom
 * 	  pair = client.recvfrom_nonblock(20)
 * 	rescue Errno::EAGAIN, Errno::EWOULDBLOCK
 * 	  IO.select([client])
 * 	  retry
 * 	end
 * 	data = pair[0].chomp
 * 	puts "I only received 20 bytes '#{data}'"
 * 	sleep 1
 * 	socket.close
 * 
 * 	# In another file, start this second
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new(AF_INET, SOCK_STREAM, 0)
 * 	sockaddr = Socket.sockaddr_in(2200, 'localhost')
 * 	socket.connect(sockaddr)
 * 	socket.puts "Watch this get cut short!"
 * 	socket.close 
 * 
 * Refer to Socket#recvfrom for the exceptions that may be thrown if the call
 * to _recvfrom_nonblock_ fails. 
 *
 * Socket#recvfrom_nonblock may raise any error corresponding to recvfrom(2) failure,
 * including Errno::EWOULDBLOCK.
 *
 * === See
 * * Socket#recvfrom
 */
static VALUE
sock_recvfrom_nonblock(int argc, VALUE *argv, VALUE sock)
{
    return s_recvfrom_nonblock(sock, argc, argv, RECV_SOCKET);
}

/*
 * call-seq:
 *   socket.accept => [client_socket, client_addrinfo]
 *
 * Accepts a next connection.
 * Returns a new Socket object and AddrInfo object.
 *
 *   serv = Socket.new(:INET, :STREAM, 0)
 *   serv.listen(5)
 *   c = Socket.new(:INET, :STREAM, 0)
 *   c.connect(serv.local_address)
 *   p serv.accept #=> [#<Socket:fd 6>, #<AddrInfo: 127.0.0.1:48555 TCP>]
 *
 */
static VALUE
sock_accept(VALUE sock)
{
    rb_io_t *fptr;
    VALUE sock2;
    char buf[1024];
    socklen_t len = sizeof buf;

    GetOpenFile(sock, fptr);
    sock2 = s_accept(rb_cSocket,fptr->fd,(struct sockaddr*)buf,&len);

    return rb_assoc_new(sock2, io_socket_addrinfo(sock2, (struct sockaddr*)buf, len));
}

/*
 * call-seq:
 * 	socket.accept_nonblock => [client_socket, client_sockaddr]
 * 
 * Accepts an incoming connection using accept(2) after
 * O_NONBLOCK is set for the underlying file descriptor.
 * It returns an array containg the accpeted socket
 * for the incoming connection, _client_socket_,
 * and a string that contains the +struct+ sockaddr information
 * about the caller, _client_sockaddr_.
 * 
 * === Example
 * 	# In one script, start this first
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new(AF_INET, SOCK_STREAM, 0)
 * 	sockaddr = Socket.sockaddr_in(2200, 'localhost')
 * 	socket.bind(sockaddr)
 * 	socket.listen(5)
 * 	begin # emulate blocking accept
 * 	  client_socket, client_sockaddr = socket.accept_nonblock
 * 	rescue Errno::EAGAIN, Errno::EWOULDBLOCK, Errno::ECONNABORTED, Errno::EPROTO, Errno::EINTR
 * 	  IO.select([socket])
 * 	  retry
 * 	end
 * 	puts "The client said, '#{client_socket.readline.chomp}'"
 * 	client_socket.puts "Hello from script one!"
 * 	socket.close
 * 
 * 	# In another script, start this second
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new(AF_INET, SOCK_STREAM, 0)
 * 	sockaddr = Socket.sockaddr_in(2200, 'localhost')
 * 	socket.connect(sockaddr)
 * 	socket.puts "Hello from script 2." 
 * 	puts "The server said, '#{socket.readline.chomp}'"
 * 	socket.close
 * 
 * Refer to Socket#accept for the exceptions that may be thrown if the call
 * to _accept_nonblock_ fails. 
 *
 * Socket#accept_nonblock may raise any error corresponding to accept(2) failure,
 * including Errno::EWOULDBLOCK.
 * 
 * === See
 * * Socket#accept
 */
static VALUE
sock_accept_nonblock(VALUE sock)
{
    rb_io_t *fptr;
    VALUE sock2;
    char buf[1024];
    socklen_t len = sizeof buf;

    GetOpenFile(sock, fptr);
    sock2 = s_accept_nonblock(rb_cSocket, fptr, (struct sockaddr *)buf, &len);
    return rb_assoc_new(sock2, io_socket_addrinfo(sock2, (struct sockaddr*)buf, len));
}

/*
 * call-seq:
 * 	socket.sysaccept => [client_socket_fd, client_sockaddr]
 * 
 * Accepts an incoming connection returnings an array containg the (integer)
 * file descriptor for the incoming connection, _client_socket_fd_,
 * and a string that contains the +struct+ sockaddr information
 * about the caller, _client_sockaddr_.
 * 
 * === Example
 * 	# In one script, start this first
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
 * 	sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
 * 	socket.bind( sockaddr )
 * 	socket.listen( 5 )
 * 	client_fd, client_sockaddr = socket.sysaccept
 * 	client_socket = Socket.for_fd( client_fd )
 * 	puts "The client said, '#{client_socket.readline.chomp}'"
 * 	client_socket.puts "Hello from script one!"
 * 	socket.close
 * 
 * 	# In another script, start this second
 * 	require 'socket'
 * 	include Socket::Constants
 * 	socket = Socket.new( AF_INET, SOCK_STREAM, 0 )
 * 	sockaddr = Socket.pack_sockaddr_in( 2200, 'localhost' )
 * 	socket.connect( sockaddr )
 * 	socket.puts "Hello from script 2." 
 * 	puts "The server said, '#{socket.readline.chomp}'"
 * 	socket.close
 * 
 * Refer to Socket#accept for the exceptions that may be thrown if the call
 * to _sysaccept_ fails. 
 * 
 * === See
 * * Socket#accept
 */
static VALUE
sock_sysaccept(VALUE sock)
{
    rb_io_t *fptr;
    VALUE sock2;
    char buf[1024];
    socklen_t len = sizeof buf;

    GetOpenFile(sock, fptr);
    sock2 = s_accept(0,fptr->fd,(struct sockaddr*)buf,&len);

    return rb_assoc_new(sock2, io_socket_addrinfo(sock2, (struct sockaddr*)buf, len));
}

#ifdef HAVE_GETHOSTNAME
/*
 * call-seq:
 *   Socket.gethostname => hostname
 *
 * Returns the hostname.
 *
 * Note that it is not guaranteed to be able to convert to IP address using gethostbyname, getaddrinfo, etc.
 *
 *   p Socket.gethostname #=> "hal"
 *
 */
static VALUE
sock_gethostname(VALUE obj)
{
    char buf[1024];

    rb_secure(3);
    if (gethostname(buf, (int)sizeof buf - 1) < 0)
	rb_sys_fail("gethostname");

    buf[sizeof buf - 1] = '\0';
    return rb_str_new2(buf);
}
#else
#ifdef HAVE_UNAME

#include <sys/utsname.h>

static VALUE
sock_gethostname(VALUE obj)
{
    struct utsname un;

    rb_secure(3);
    uname(&un);
    return rb_str_new2(un.nodename);
}
#else
static VALUE
sock_gethostname(VALUE obj)
{
    rb_notimplement();
}
#endif
#endif

static VALUE
make_addrinfo(struct addrinfo *res0)
{
    VALUE base, ary;
    struct addrinfo *res;

    if (res0 == NULL) {
	rb_raise(rb_eSocket, "host not found");
    }
    base = rb_ary_new();
    for (res = res0; res; res = res->ai_next) {
	ary = ipaddr(res->ai_addr, do_not_reverse_lookup);
	if (res->ai_canonname) {
	    RARRAY_PTR(ary)[2] = rb_str_new2(res->ai_canonname);
	}
	rb_ary_push(ary, INT2FIX(res->ai_family));
	rb_ary_push(ary, INT2FIX(res->ai_socktype));
	rb_ary_push(ary, INT2FIX(res->ai_protocol));
	rb_ary_push(base, ary);
    }
    return base;
}

static VALUE
sock_sockaddr(struct sockaddr *addr, size_t len)
{
    char *ptr;

    switch (addr->sa_family) {
      case AF_INET:
	ptr = (char*)&((struct sockaddr_in*)addr)->sin_addr.s_addr;
	len = sizeof(((struct sockaddr_in*)addr)->sin_addr.s_addr);
	break;
#ifdef INET6
      case AF_INET6:
	ptr = (char*)&((struct sockaddr_in6*)addr)->sin6_addr.s6_addr;
	len = sizeof(((struct sockaddr_in6*)addr)->sin6_addr.s6_addr);
	break;
#endif
      default:
        rb_raise(rb_eSocket, "unknown socket family:%d", addr->sa_family);
	break;
    }
    return rb_str_new(ptr, len);
}

/*
 * call-seq:
 *   Socket.gethostbyname(hostname) => [official_hostname, alias_hostnames, address_family, *address_list]
 *
 * Obtains the host information for _hostname_.
 *
 *   p Socket.gethostbyname("hal") #=> ["localhost", ["hal"], 2, "\x7F\x00\x00\x01"]
 *
 */
static VALUE
sock_s_gethostbyname(VALUE obj, VALUE host)
{
    rb_secure(3);
    return make_hostent(host, sock_addrinfo(host, Qnil, SOCK_STREAM, AI_CANONNAME), sock_sockaddr);
}

/*
 * call-seq:
 *   Socket.gethostbyaddr(address_string [, address_family]) => hostent
 *
 * Obtains the host information for _address_.
 *
 *   p Socket.gethostbyaddr([221,186,184,68].pack("CCCC"))              
 *   #=> ["carbon.ruby-lang.org", [], 2, "\xDD\xBA\xB8D"]
 */
static VALUE
sock_s_gethostbyaddr(int argc, VALUE *argv)
{
    VALUE addr, family;
    struct hostent *h;
    struct sockaddr *sa;
    char **pch;
    VALUE ary, names;
    int t = AF_INET;

    rb_scan_args(argc, argv, "11", &addr, &family);
    sa = (struct sockaddr*)StringValuePtr(addr);
    if (!NIL_P(family)) {
	t = family_arg(family);
    }
#ifdef INET6
    else if (RSTRING_LEN(addr) == 16) {
	t = AF_INET6;
    }
#endif
    h = gethostbyaddr(RSTRING_PTR(addr), RSTRING_LEN(addr), t);
    if (h == NULL) {
#ifdef HAVE_HSTRERROR
	extern int h_errno;
	rb_raise(rb_eSocket, "%s", (char*)hstrerror(h_errno));
#else
	rb_raise(rb_eSocket, "host not found");
#endif
    }
    ary = rb_ary_new();
    rb_ary_push(ary, rb_str_new2(h->h_name));
    names = rb_ary_new();
    rb_ary_push(ary, names);
    if (h->h_aliases != NULL) {
	for (pch = h->h_aliases; *pch; pch++) {
	    rb_ary_push(names, rb_str_new2(*pch));
	}
    }
    rb_ary_push(ary, INT2NUM(h->h_addrtype));
#ifdef h_addr
    for (pch = h->h_addr_list; *pch; pch++) {
	rb_ary_push(ary, rb_str_new(*pch, h->h_length));
    }
#else
    rb_ary_push(ary, rb_str_new(h->h_addr, h->h_length));
#endif

    return ary;
}

/*
 * call-seq:
 *   Socket.getservbyname(service_name)                => port_number
 *   Socket.getservbyname(service_name, protocol_name) => port_number
 *
 * Obtains the port number for _service_name_.
 *
 * If _protocol_name_ is not given, "tcp" is assumed.
 *
 *   Socket.getservbyname("smtp")          #=> 25
 *   Socket.getservbyname("shell")         #=> 514
 *   Socket.getservbyname("syslog", "udp") #=> 514
 */   
static VALUE
sock_s_getservbyname(int argc, VALUE *argv)
{
    VALUE service, proto;
    struct servent *sp;
    int port;
    const char *servicename, *protoname = "tcp";

    rb_scan_args(argc, argv, "11", &service, &proto);
    StringValue(service);
    if (!NIL_P(proto)) StringValue(proto);
    servicename = StringValueCStr(service);
    if (!NIL_P(proto)) protoname = StringValueCStr(proto);
    sp = getservbyname(servicename, protoname);
    if (sp) {
	port = ntohs(sp->s_port);
    }
    else {
	char *end;

	port = STRTOUL(servicename, &end, 0);
	if (*end != '\0') {
	    rb_raise(rb_eSocket, "no such service %s/%s", servicename, protoname);
	}
    }
    return INT2FIX(port);
}

/*
 * call-seq:
 *   Socket.getservbyport(port [, protocol_name]) => service
 *
 * Obtains the port number for _port_.
 *
 * If _protocol_name_ is not given, "tcp" is assumed.
 *
 *   Socket.getservbyport(80)         #=> "www"
 *   Socket.getservbyport(514, "tcp") #=> "shell"
 *   Socket.getservbyport(514, "udp") #=> "syslog"
 *
 */
static VALUE
sock_s_getservbyport(int argc, VALUE *argv)
{
    VALUE port, proto;
    struct servent *sp;
    long portnum;
    const char *protoname = "tcp";

    rb_scan_args(argc, argv, "11", &port, &proto);
    portnum = NUM2LONG(port);
    if (portnum != (uint16_t)portnum) {
	const char *s = portnum > 0 ? "big" : "small";
	rb_raise(rb_eRangeError, "integer %ld too %s to convert into `int16_t'", portnum, s);
    }
    if (!NIL_P(proto)) protoname = StringValueCStr(proto);

    sp = getservbyport((int)htons((uint16_t)portnum), protoname);
    if (!sp) {
	rb_raise(rb_eSocket, "no such service for port %d/%s", (int)portnum, protoname);
    }
    return rb_tainted_str_new2(sp->s_name);
}

/*
 * call-seq:
 *   Socket.getaddrinfo(nodename, servname[, family[, socktype[, protocol[, flags]]]]) => array
 *
 * Obtains address information for _nodename_:_servname_.
 *
 * _family_ should be an address family such as: :INET, :INET6, :UNIX, etc.
 *
 * _socktype_ should be a socket type such as: :STREAM, :DGRAM, :RAW, etc.
 *
 * _protocol_ should be a protocol defined in the family.
 * 0 is default protocol for the family.
 *
 * _flags_ should be bitwise OR of Socket::AI_* constants.
 *
 *   Socket.getaddrinfo("www.ruby-lang.org", "http", nil, :STREAM)
 *   #=> [["AF_INET", 80, "carbon.ruby-lang.org", "221.186.184.68", 2, 1, 6]] # PF_INET/SOCK_STREAM/IPPROTO_TCP
 *
 *   Socket.getaddrinfo("localhost", nil)
 *   #=> [["AF_INET", 0, "localhost", "127.0.0.1", 2, 1, 6],  # PF_INET/SOCK_STREAM/IPPROTO_TCP
 *   #    ["AF_INET", 0, "localhost", "127.0.0.1", 2, 2, 17], # PF_INET/SOCK_DGRAM/IPPROTO_UDP
 *   #    ["AF_INET", 0, "localhost", "127.0.0.1", 2, 3, 0]]  # PF_INET/SOCK_RAW/IPPROTO_IP
 *
 */
static VALUE
sock_s_getaddrinfo(int argc, VALUE *argv)
{
    VALUE host, port, family, socktype, protocol, flags, ret;
    struct addrinfo hints, *res;

    rb_scan_args(argc, argv, "24", &host, &port, &family, &socktype, &protocol, &flags);

    MEMZERO(&hints, struct addrinfo, 1);
    hints.ai_family = NIL_P(family) ? PF_UNSPEC : family_arg(family);

    if (!NIL_P(socktype)) {
	hints.ai_socktype = socktype_arg(socktype);
    }
    if (!NIL_P(protocol)) {
	hints.ai_protocol = NUM2INT(protocol);
    }
    if (!NIL_P(flags)) {
	hints.ai_flags = NUM2INT(flags);
    }
    res = sock_getaddrinfo(host, port, &hints, 0);

    ret = make_addrinfo(res);
    freeaddrinfo(res);
    return ret;
}

/*
 * call-seq:
 *   Socket.getnameinfo(sockaddr [, flags]) => [hostname, servicename]
 *
 * Obtains name information for _sockaddr_.
 *
 * _sockaddr_ should be one of follows.
 * - packed sockddr string such as Socket.sockaddr_in(80, "127.0.0.1")
 * - 3-elements array such as ["AF_INET", 80, "127.0.0.1"]
 * - 4-elements array such as ["AF_INET", 80, ignored, "127.0.0.1"]
 *
 * _flags_ should be bitwise OR of Socket::NI_* constants.
 *
 * Note that the last form is compatible with IPSocket#{addr,peeraddr}.
 *
 *   Socket.getnameinfo(Socket.sockaddr_in(80, "127.0.0.1"))       #=> ["localhost", "www"]
 *   Socket.getnameinfo(["AF_INET", 80, "127.0.0.1"])              #=> ["localhost", "www"]
 *   Socket.getnameinfo(["AF_INET", 80, "localhost", "127.0.0.1"]) #=> ["localhost", "www"]
 */
static VALUE
sock_s_getnameinfo(int argc, VALUE *argv)
{
    VALUE sa, af = Qnil, host = Qnil, port = Qnil, flags, tmp;
    char *hptr, *pptr;
    char hbuf[1024], pbuf[1024];
    int fl;
    struct addrinfo hints, *res = NULL, *r;
    int error;
    struct sockaddr_storage ss;
    struct sockaddr *sap;

    sa = flags = Qnil;
    rb_scan_args(argc, argv, "11", &sa, &flags);

    fl = 0;
    if (!NIL_P(flags)) {
	fl = NUM2INT(flags);
    }
    tmp = rb_check_string_type(sa);
    if (!NIL_P(tmp)) {
	sa = tmp;
	if (sizeof(ss) < RSTRING_LEN(sa)) {
	    rb_raise(rb_eTypeError, "sockaddr length too big");
	}
	memcpy(&ss, RSTRING_PTR(sa), RSTRING_LEN(sa));
	if (RSTRING_LEN(sa) != SA_LEN((struct sockaddr*)&ss)) {
	    rb_raise(rb_eTypeError, "sockaddr size differs - should not happen");
	}
	sap = (struct sockaddr*)&ss;
	goto call_nameinfo;
    }
    tmp = rb_check_array_type(sa);
    if (!NIL_P(tmp)) {
	sa = tmp;
	MEMZERO(&hints, struct addrinfo, 1);
	if (RARRAY_LEN(sa) == 3) {
	    af = RARRAY_PTR(sa)[0];
	    port = RARRAY_PTR(sa)[1];
	    host = RARRAY_PTR(sa)[2];
	}
	else if (RARRAY_LEN(sa) >= 4) {
	    af = RARRAY_PTR(sa)[0];
	    port = RARRAY_PTR(sa)[1];
	    host = RARRAY_PTR(sa)[3];
	    if (NIL_P(host)) {
		host = RARRAY_PTR(sa)[2];
	    }
	    else {
		/*
		 * 4th element holds numeric form, don't resolve.
		 * see ipaddr().
		 */
#ifdef AI_NUMERICHOST /* AIX 4.3.3 doesn't have AI_NUMERICHOST. */
		hints.ai_flags |= AI_NUMERICHOST;
#endif
	    }
	}
	else {
	    rb_raise(rb_eArgError, "array size should be 3 or 4, %ld given",
		     RARRAY_LEN(sa));
	}
	/* host */
	if (NIL_P(host)) {
	    hptr = NULL;
	}
	else {
	    strncpy(hbuf, StringValuePtr(host), sizeof(hbuf));
	    hbuf[sizeof(hbuf) - 1] = '\0';
	    hptr = hbuf;
	}
	/* port */
	if (NIL_P(port)) {
	    strcpy(pbuf, "0");
	    pptr = NULL;
	}
	else if (FIXNUM_P(port)) {
	    snprintf(pbuf, sizeof(pbuf), "%ld", NUM2LONG(port));
	    pptr = pbuf;
	}
	else {
	    strncpy(pbuf, StringValuePtr(port), sizeof(pbuf));
	    pbuf[sizeof(pbuf) - 1] = '\0';
	    pptr = pbuf;
	}
	hints.ai_socktype = (fl & NI_DGRAM) ? SOCK_DGRAM : SOCK_STREAM;
	/* af */
        hints.ai_family = NIL_P(af) ? PF_UNSPEC : family_arg(af);
	error = rb_getaddrinfo(hptr, pptr, &hints, &res);
	if (error) goto error_exit_addr;
	sap = res->ai_addr;
    }
    else {
	rb_raise(rb_eTypeError, "expecting String or Array");
    }

  call_nameinfo:
    error = rb_getnameinfo(sap, SA_LEN(sap), hbuf, sizeof(hbuf),
			   pbuf, sizeof(pbuf), fl);
    if (error) goto error_exit_name;
    if (res) {
	for (r = res->ai_next; r; r = r->ai_next) {
	    char hbuf2[1024], pbuf2[1024];

	    sap = r->ai_addr;
	    error = rb_getnameinfo(sap, SA_LEN(sap), hbuf2, sizeof(hbuf2),
				   pbuf2, sizeof(pbuf2), fl);
	    if (error) goto error_exit_name;
	    if (strcmp(hbuf, hbuf2) != 0|| strcmp(pbuf, pbuf2) != 0) {
		freeaddrinfo(res);
		rb_raise(rb_eSocket, "sockaddr resolved to multiple nodename");
	    }
	}
	freeaddrinfo(res);
    }
    return rb_assoc_new(rb_str_new2(hbuf), rb_str_new2(pbuf));

  error_exit_addr:
    if (res) freeaddrinfo(res);
    raise_socket_error("getaddrinfo", error);

  error_exit_name:
    if (res) freeaddrinfo(res);
    raise_socket_error("getnameinfo", error);
}

/*
 * call-seq:
 *   Socket.sockaddr_in(port, host)      => sockaddr
 *   Socket.pack_sockaddr_in(port, host) => sockaddr
 *
 * Packs _port_ and _host_ as an AF_INET/AF_INET6 sockaddr string.
 *
 *   Socket.sockaddr_in(80, "127.0.0.1")
 *   #=> "\x02\x00\x00P\x7F\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00"
 *
 *   Socket.sockaddr_in(80, "::1")
 *   #=> "\n\x00\x00P\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00\x00\x00"
 *
 */
static VALUE
sock_s_pack_sockaddr_in(VALUE self, VALUE port, VALUE host)
{
    struct addrinfo *res = sock_addrinfo(host, port, 0, 0);
    VALUE addr = rb_str_new((char*)res->ai_addr, res->ai_addrlen);

    freeaddrinfo(res);
    OBJ_INFECT(addr, port);
    OBJ_INFECT(addr, host);

    return addr;
}

/*
 * call-seq:
 *   Socket.unpack_sockaddr_in(sockaddr) => [port, ip_address]
 *
 * Unpacks _sockaddr_ into port and ip_address.
 *
 * _sockaddr_ should be a string or an addrinfo for AF_INET/AF_INET6.
 *
 *   sockaddr = Socket.sockaddr_in(80, "127.0.0.1")
 *   p sockaddr #=> "\x02\x00\x00P\x7F\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00"
 *   p Socket.unpack_sockaddr_in(sockaddr) #=> [80, "127.0.0.1"]
 *
 */
static VALUE
sock_s_unpack_sockaddr_in(VALUE self, VALUE addr)
{
    struct sockaddr_in * sockaddr;
    VALUE host;

    sockaddr = (struct sockaddr_in*)SockAddrStringValuePtr(addr);
    if (((struct sockaddr *)sockaddr)->sa_family != AF_INET
#ifdef INET6
        && ((struct sockaddr *)sockaddr)->sa_family != AF_INET6
#endif
        ) {
#ifdef INET6
        rb_raise(rb_eArgError, "not an AF_INET/AF_INET6 sockaddr");
#else
        rb_raise(rb_eArgError, "not an AF_INET sockaddr");
#endif
    }
    host = make_ipaddr((struct sockaddr*)sockaddr);
    OBJ_INFECT(host, addr);
    return rb_assoc_new(INT2NUM(ntohs(sockaddr->sin_port)), host);
}

#ifdef HAVE_SYS_UN_H

/*
 * call-seq:
 *   Socket.sockaddr_un(path)      => sockaddr
 *   Socket.pack_sockaddr_un(path) => sockaddr
 *
 * Packs _path_ as an AF_UNIX sockaddr string.
 *
 *   Socket.sockaddr_un("/tmp/sock") #=> "\x01\x00/tmp/sock\x00\x00..."
 *
 */
static VALUE
sock_s_pack_sockaddr_un(VALUE self, VALUE path)
{
    struct sockaddr_un sockaddr;
    char *sun_path;
    VALUE addr;

    MEMZERO(&sockaddr, struct sockaddr_un, 1);
    sockaddr.sun_family = AF_UNIX;
    sun_path = StringValueCStr(path);
    if (sizeof(sockaddr.sun_path) <= strlen(sun_path)) {
        rb_raise(rb_eArgError, "too long unix socket path (max: %dbytes)",
            (int)sizeof(sockaddr.sun_path)-1);
    }
    strncpy(sockaddr.sun_path, sun_path, sizeof(sockaddr.sun_path)-1);
    addr = rb_str_new((char*)&sockaddr, sizeof(sockaddr));
    OBJ_INFECT(addr, path);

    return addr;
}

/*
 * call-seq:
 *   Socket.unpack_sockaddr_un(sockaddr) => path
 *
 * Unpacks _sockaddr_ into path.
 *
 * _sockaddr_ should be a string or an addrinfo for AF_UNIX.
 *
 *   sockaddr = Socket.sockaddr_un("/tmp/sock") 
 *   p Socket.unpack_sockaddr_un(sockaddr) #=> "/tmp/sock"
 *
 */
static VALUE
sock_s_unpack_sockaddr_un(VALUE self, VALUE addr)
{
    struct sockaddr_un * sockaddr;
    const char *sun_path;
    VALUE path;

    sockaddr = (struct sockaddr_un*)SockAddrStringValuePtr(addr);
    if (((struct sockaddr *)sockaddr)->sa_family != AF_UNIX) {
        rb_raise(rb_eArgError, "not an AF_UNIX sockaddr");
    }
    if (sizeof(struct sockaddr_un) < RSTRING_LEN(addr)) {
	rb_raise(rb_eTypeError, "too long sockaddr_un - %ld longer than %d",
		 RSTRING_LEN(addr), (int)sizeof(struct sockaddr_un));
    }
    sun_path = unixpath(sockaddr, RSTRING_LEN(addr));
    if (sizeof(struct sockaddr_un) == RSTRING_LEN(addr) &&
        sun_path == sockaddr->sun_path &&
        sun_path + strlen(sun_path) == RSTRING_PTR(addr) + RSTRING_LEN(addr)) {
        rb_raise(rb_eArgError, "sockaddr_un.sun_path not NUL terminated");
    }
    path = rb_str_new2(sun_path);
    OBJ_INFECT(path, addr);
    return path;
}
#endif

typedef struct {
    VALUE inspectname;
    VALUE canonname;
    int pfamily;
    int socktype;
    int protocol;
    size_t sockaddr_len;
    struct sockaddr_storage addr;
} rb_addrinfo_t;

static void
addrinfo_mark(rb_addrinfo_t *rai)
{
    if (rai) {
        rb_gc_mark(rai->inspectname);
        rb_gc_mark(rai->canonname);
    }
}

static void
addrinfo_free(rb_addrinfo_t *rai)
{
    xfree(rai);
}

static VALUE
addrinfo_s_allocate(VALUE klass)
{
    return Data_Wrap_Struct(klass, addrinfo_mark, addrinfo_free, 0);
}

#define IS_ADDRINFO(obj) (RDATA(obj)->dmark == (RUBY_DATA_FUNC)addrinfo_mark)
static rb_addrinfo_t *
check_addrinfo(VALUE self)
{
    Check_Type(self, RUBY_T_DATA);
    if (!IS_ADDRINFO(self)) {
        rb_raise(rb_eTypeError, "wrong argument type %s (expected AddrInfo)",
                 rb_class2name(CLASS_OF(self)));
    }
    return DATA_PTR(self);
}

static rb_addrinfo_t *
get_addrinfo(VALUE self)
{
    rb_addrinfo_t *rai = check_addrinfo(self);

    if (!rai) {
        rb_raise(rb_eTypeError, "uninitialized socket address");
    }
    return rai;
}


static rb_addrinfo_t *
alloc_addrinfo()
{
    rb_addrinfo_t *rai = ALLOC(rb_addrinfo_t);
    memset(rai, 0, sizeof(rb_addrinfo_t));
    rai->inspectname = Qnil;
    rai->canonname = Qnil;
    return rai;
}

static void
init_addrinfo(rb_addrinfo_t *rai, struct sockaddr *sa, size_t len,
              int pfamily, int socktype, int protocol,
              VALUE canonname, VALUE inspectname)
{
    if (sizeof(rai->addr) < len)
        rb_raise(rb_eArgError, "sockaddr string too big");
    memcpy((void *)&rai->addr, (void *)sa, len);
    rai->sockaddr_len = len;

    rai->pfamily = pfamily;
    rai->socktype = socktype;
    rai->protocol = protocol;
    rai->canonname = canonname;
    rai->inspectname = inspectname;
}

static VALUE
addrinfo_new(struct sockaddr *addr, socklen_t len,
             int family, int socktype, int protocol,
             VALUE canonname, VALUE inspectname)
{
    VALUE a;
    rb_addrinfo_t *rai;

    a = addrinfo_s_allocate(rb_cAddrInfo);
    DATA_PTR(a) = rai = alloc_addrinfo();
    init_addrinfo(rai, addr, len, family, socktype, protocol, canonname, inspectname);
    return a;
}

static struct addrinfo *
call_getaddrinfo(VALUE node, VALUE service,
                 VALUE family, VALUE socktype, VALUE protocol, VALUE flags,
                 int socktype_hack)
{
    struct addrinfo hints, *res;

    MEMZERO(&hints, struct addrinfo, 1);
    hints.ai_family = NIL_P(family) ? PF_UNSPEC : family_arg(family);

    if (!NIL_P(socktype)) {
	hints.ai_socktype = socktype_arg(socktype);
    }
    if (!NIL_P(protocol)) {
	hints.ai_protocol = NUM2INT(protocol);
    }
    if (!NIL_P(flags)) {
	hints.ai_flags = NUM2INT(flags);
    }
    res = sock_getaddrinfo(node, service, &hints, socktype_hack);

    if (res == NULL)
	rb_raise(rb_eSocket, "host not found");
    return res;
}

static void
init_addrinfo_getaddrinfo(rb_addrinfo_t *rai, VALUE node, VALUE service,
                          VALUE family, VALUE socktype, VALUE protocol, VALUE flags,
                          VALUE inspectname)
{
    struct addrinfo *res = call_getaddrinfo(node, service, family, socktype, protocol, flags, 1);
    VALUE canonname;

    canonname = Qnil;
    if (res->ai_canonname) {
        canonname = rb_tainted_str_new_cstr(res->ai_canonname);
        OBJ_FREEZE(canonname);
    }

    init_addrinfo(rai, res->ai_addr, res->ai_addrlen,
                  NUM2INT(family), NUM2INT(socktype), NUM2INT(protocol),
                  canonname, inspectname);

    freeaddrinfo(res);
}

static VALUE
make_inspectname(VALUE node, VALUE service)
{
    VALUE inspectname = Qnil;
    if (TYPE(node) == T_STRING) {
        inspectname = rb_str_dup(node);
    }
    if (TYPE(service) == T_STRING) {
        if (NIL_P(inspectname))
            inspectname = rb_sprintf(":%s", StringValueCStr(service));
        else
            rb_str_catf(inspectname, ":%s", StringValueCStr(service));
    }
    else if (TYPE(service) == T_FIXNUM && FIX2INT(service) != 0)
    {
        if (NIL_P(inspectname))
            inspectname = rb_sprintf(":%d", FIX2INT(service));
        else
            rb_str_catf(inspectname, ":%d", FIX2INT(service));
    }
    if (!NIL_P(inspectname)) {
        OBJ_INFECT(inspectname, node);
        OBJ_INFECT(inspectname, service);
        OBJ_FREEZE(inspectname);
    }
    return inspectname;
}

static VALUE
addrinfo_firstonly_new(VALUE node, VALUE service, VALUE family, VALUE socktype, VALUE protocol, VALUE flags)
{
    VALUE ret;
    VALUE canonname;
    VALUE inspectname;

    struct addrinfo *res = call_getaddrinfo(node, service, family, socktype, protocol, flags, 0);

    inspectname = make_inspectname(node, service);

    canonname = Qnil;
    if (res->ai_canonname) {
        canonname = rb_tainted_str_new_cstr(res->ai_canonname);
        OBJ_FREEZE(canonname);
    }

    ret = addrinfo_new(res->ai_addr, res->ai_addrlen,
                       res->ai_family, res->ai_socktype, res->ai_protocol,
                       canonname, inspectname);

    freeaddrinfo(res);
    return ret;
}

static VALUE
addrinfo_list_new(VALUE node, VALUE service, VALUE family, VALUE socktype, VALUE protocol, VALUE flags)
{
    VALUE ret;
    struct addrinfo *r;
    VALUE inspectname;

    struct addrinfo *res = call_getaddrinfo(node, service, family, socktype, protocol, flags, 0);

    inspectname = make_inspectname(node, service);

    ret = rb_ary_new();
    for (r = res; r; r = r->ai_next) {
        VALUE addr;
        VALUE canonname = Qnil;

        if (r->ai_canonname) {
            canonname = rb_tainted_str_new_cstr(r->ai_canonname);
            OBJ_FREEZE(canonname);
        }

        addr = addrinfo_new(r->ai_addr, r->ai_addrlen,
                            r->ai_family, r->ai_socktype, r->ai_protocol,
                            canonname, inspectname);

        rb_ary_push(ret, addr);
    }

    freeaddrinfo(res);
    return ret;
}


#ifdef HAVE_SYS_UN_H
static void
init_unix_addrinfo(rb_addrinfo_t *rai, VALUE path)
{
    struct sockaddr_un un;

    StringValue(path);

    if (sizeof(un.sun_path) <= RSTRING_LEN(path))
        rb_raise(rb_eArgError, "too long unix socket path (max: %dbytes)",
            (int)sizeof(un.sun_path)-1);

    MEMZERO(&un, struct sockaddr_un, 1);

    un.sun_family = AF_UNIX;
    memcpy((void*)&un.sun_path, RSTRING_PTR(path), RSTRING_LEN(path));
   
    init_addrinfo(rai, (struct sockaddr *)&un, sizeof(un), AF_UNIX, SOCK_STREAM, 0, Qnil, Qnil);
}
#endif

/*
 * call-seq:
 *   AddrInfo.new(sockaddr)                             => addrinfo
 *   AddrInfo.new(sockaddr, family)                     => addrinfo
 *   AddrInfo.new(sockaddr, family, socktype)           => addrinfo
 *   AddrInfo.new(sockaddr, family, socktype, protocol) => addrinfo
 *
 * returns a new instance of AddrInfo.
 * It the instnace contains sockaddr, family, socktype, protocol.
 * sockaddr means struct sockaddr which can be used for connect(2), etc.
 * family, socktype and protocol are integers which is used for arguments of socket(2).
 *
 * sockaddr is specified as an array or a string.
 * The array should be compatible to the value of IPSocket#addr or UNIXSocket#addr.
 * The string should be struct sockaddr as generated by
 * Socket.sockaddr_in or Socket.unpack_sockaddr_un.
 *
 * sockaddr examples:
 * - ["AF_INET", 46102, "localhost.localdomain", "127.0.0.1"] 
 * - ["AF_INET6", 42304, "ip6-localhost", "::1"] 
 * - ["AF_UNIX", "/tmp/sock"] 
 * - Socket.sockaddr_in("smtp", "2001:DB8::1")
 * - Socket.sockaddr_in(80, "172.18.22.42")
 * - Socket.sockaddr_in(80, "www.ruby-lang.org")
 * - Socket.sockaddr_un("/tmp/sock")
 *
 * In an AF_INET/AF_INET6 sockaddr array, the 4th element,
 * numeric IP address, is used to construct socket address in the AddrInfo instance.
 * The 3rd element, textual host name, is also recorded but only used for AddrInfo#inspect.
 *
 * family is specified as an integer to specify the protocol family such as Socket::PF_INET.
 * It can be a symbol or a string which is the constant name
 * with or without PF_ prefix such as :INET, :INET6, :UNIX, "PF_INET", etc.
 * If ommitted, PF_UNSPEC is assumed.
 *
 * socktype is specified as an integer to specify the socket type such as Socket::SOCK_STREAM.
 * It can be a symbol or a string which is the constant name
 * with or without SOCK_ prefix such as :STREAM, :DGRAM, :RAW, "SOCK_STREAM", etc.
 * If ommitted, 0 is assumed.
 *
 * protocol is specified as an integer to specify the protocol such as Socket::IPPROTO_TCP.
 * It must be an integer, unlike family and socktype.
 * If ommitted, 0 is assumed.
 * Note that 0 is reasonable value for most protocols, except raw socket.
 *
 */
static VALUE
addrinfo_initialize(int argc, VALUE *argv, VALUE self)
{
    rb_addrinfo_t *rai;
    VALUE sockaddr_arg, sockaddr_ary, pfamily, socktype, protocol;
    int i_pfamily, i_socktype, i_protocol;
    struct sockaddr *sockaddr_ptr;
    size_t sockaddr_len;
    VALUE canonname = Qnil, inspectname = Qnil;

    if (check_addrinfo(self))
        rb_raise(rb_eTypeError, "already initialized socket address");
    DATA_PTR(self) = rai = alloc_addrinfo();

    rb_scan_args(argc, argv, "13", &sockaddr_arg, &pfamily, &socktype, &protocol);

    i_pfamily = NIL_P(pfamily) ? PF_UNSPEC : family_arg(pfamily);
    i_socktype = NIL_P(socktype) ? 0 : socktype_arg(socktype);
    i_protocol = NIL_P(protocol) ? 0 : NUM2INT(protocol);

    sockaddr_ary = rb_check_array_type(sockaddr_arg);
    if (!NIL_P(sockaddr_ary)) {
        VALUE afamily = rb_ary_entry(sockaddr_ary, 0);
        int af;
        StringValue(afamily);
        if (family_to_int(RSTRING_PTR(afamily), RSTRING_LEN(afamily), &af) == -1)
	    rb_raise(rb_eSocket, "unknown address family: %s", StringValueCStr(afamily));
        switch (af) {
          case AF_INET: /* ["AF_INET", 46102, "localhost.localdomain", "127.0.0.1"] */
#ifdef INET6
          case AF_INET6: /* ["AF_INET6", 42304, "ip6-localhost", "::1"] */
#endif
          {
            VALUE service = rb_ary_entry(sockaddr_ary, 1);
            VALUE nodename = rb_ary_entry(sockaddr_ary, 2);
            VALUE numericnode = rb_ary_entry(sockaddr_ary, 3);
            int flags;

            service = INT2NUM(NUM2INT(service));
            if (!NIL_P(nodename))
                StringValue(nodename);
            StringValue(numericnode);
            flags = AI_NUMERICHOST;
#ifdef AI_NUMERICSERV
            flags |= AI_NUMERICSERV;
#endif

            init_addrinfo_getaddrinfo(rai, numericnode, service,
                    INT2NUM(i_pfamily ? i_pfamily : af), INT2NUM(i_socktype), INT2NUM(i_protocol),
                    INT2NUM(flags),
                    rb_str_equal(numericnode, nodename) ? Qnil : make_inspectname(nodename, service));
            break;
          }

#ifdef HAVE_SYS_UN_H
          case AF_UNIX: /* ["AF_UNIX", "/tmp/sock"] */
          {
            VALUE path = rb_ary_entry(sockaddr_ary, 1);
            StringValue(path);
            init_unix_addrinfo(rai, path);
            break;
          }
#endif

          default:
            rb_raise(rb_eSocket, "unexpected address family");
        }
    }
    else {
        StringValue(sockaddr_arg);
        sockaddr_ptr = (struct sockaddr *)RSTRING_PTR(sockaddr_arg);
        sockaddr_len = RSTRING_LEN(sockaddr_arg);
        init_addrinfo(rai, sockaddr_ptr, sockaddr_len,
                      i_pfamily, i_socktype, i_protocol,
                      canonname, inspectname);
    }

    return self;
}

static int
ai_get_afamily(rb_addrinfo_t *rai)
{
    return get_afamily((struct sockaddr *)&rai->addr, rai->sockaddr_len);
}

/*
 * call-seq:
 *   addrinfo.inspect => string
 *
 * returns a string which shows addrinfo in human-readable form.
 *
 *   AddrInfo.tcp("localhost", 80).inspect #=> "#<AddrInfo: 127.0.0.1:80 TCP (localhost:80)>"
 *   AddrInfo.unix("/tmp/sock").inspect    #=> "#<AddrInfo: /tmp/sock SOCK_STREAM>"
 *
 */
static VALUE
addrinfo_inspect(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    int internet_p;
    VALUE ret;

    ret = rb_sprintf("#<%s: ", rb_obj_classname(self));

    if (rai->sockaddr_len == 0) {
        rb_str_cat2(ret, "empty-sockaddr");
    }
    else if (rai->sockaddr_len < ((char*)&rai->addr.ss_family + sizeof(rai->addr.ss_family)) - (char*)&rai->addr)
        rb_str_cat2(ret, "too-short-sockaddr");
    else {
        switch (rai->addr.ss_family) {
          case AF_INET:
          {
            struct sockaddr_in *addr;
            int port;
            if (rai->sockaddr_len < sizeof(struct sockaddr_in)) {
                rb_str_cat2(ret, "too-short-AF_INET-sockaddr");
            }
            else {
                addr = (struct sockaddr_in *)&rai->addr;
                rb_str_catf(ret, "%d.%d.%d.%d",
                            ((unsigned char*)&addr->sin_addr)[0],
                            ((unsigned char*)&addr->sin_addr)[1],
                            ((unsigned char*)&addr->sin_addr)[2],
                            ((unsigned char*)&addr->sin_addr)[3]);
                port = ntohs(addr->sin_port);
                if (port)
                    rb_str_catf(ret, ":%d", port);
                if (sizeof(struct sockaddr_in) < rai->sockaddr_len)
                    rb_str_catf(ret, "(sockaddr %d bytes too long)", (int)(rai->sockaddr_len - sizeof(struct sockaddr_in)));
            }
            break;
          }

#ifdef INET6
          case AF_INET6:
          {
            struct sockaddr_in6 *addr;
            char hbuf[1024];
            int port;
            int error;
            if (rai->sockaddr_len < sizeof(struct sockaddr_in6)) {
                rb_str_cat2(ret, "too-short-AF_INET6-sockaddr");
            }
            else {
                addr = (struct sockaddr_in6 *)&rai->addr;
                /* use getnameinfo for scope_id.
                 * RFC 4007: IPv6 Scoped Address Architecture
                 * draft-ietf-ipv6-scope-api-00.txt: Scoped Address Extensions to the IPv6 Basic Socket API
                 */
                error = getnameinfo((struct sockaddr *)&rai->addr, rai->sockaddr_len,
                                    hbuf, sizeof(hbuf), NULL, 0,
                                    NI_NUMERICHOST|NI_NUMERICSERV);
                if (error) {
                    raise_socket_error("getnameinfo", error);
                }
                if (addr->sin6_port == 0) {
                    rb_str_cat2(ret, hbuf);
                }
                else {
                    port = ntohs(addr->sin6_port);
                    rb_str_catf(ret, "[%s]:%d", hbuf, port);
                }
                if (sizeof(struct sockaddr_in6) < rai->sockaddr_len)
                    rb_str_catf(ret, "(sockaddr %d bytes too long)", (int)(rai->sockaddr_len - sizeof(struct sockaddr_in6)));
            }
            break;
          }
#endif

#ifdef HAVE_SYS_UN_H
          case AF_UNIX:
          {
            struct sockaddr_un *addr = (struct sockaddr_un *)&rai->addr;
            char *p, *s, *t, *e;
            s = addr->sun_path;
            e = (char*)addr + rai->sockaddr_len;
            if (e < s)
                rb_str_cat2(ret, "too-short-AF_UNIX-sockaddr");
            else if (s == e)
                rb_str_cat2(ret, "empty-path-AF_UNIX-sockaddr");
            else {
                int printable_only = 1;
                p = s;
                while (p < e && *p != '\0') {
                    printable_only = printable_only && ISPRINT(*p) && !ISSPACE(*p);
                    p++;
                }
                t = p;
                while (p < e && *p == '\0')
                    p++;
                if (printable_only && /* only printable, no space */
                    t < e && /* NUL terminated */
                    p == e) { /* no data after NUL */
		    if (s == t)
			rb_str_cat2(ret, "empty-path-AF_UNIX-sockaddr");
		    else if (s[0] == '/') /* absolute path */
			rb_str_cat2(ret, s);
		    else
                        rb_str_catf(ret, "AF_UNIX %s", s);
                }
                else {
                    rb_str_cat2(ret, "AF_UNIX");
                    e = (char *)addr->sun_path + sizeof(addr->sun_path);
                    while (s < e && *(e-1) == '\0')
                        e--;
                    while (s < e)
                        rb_str_catf(ret, ":%02x", (unsigned char)*s++);
                }
                if (addr->sun_path + sizeof(addr->sun_path) < (char*)&rai->addr + rai->sockaddr_len)
                    rb_str_catf(ret, "(sockaddr %d bytes too long)",
                            (int)(rai->sockaddr_len - (addr->sun_path + sizeof(addr->sun_path) - (char*)&rai->addr)));
            }
            break;
          }
#endif

          default:
          {
            ID id = intern_family(rai->addr.ss_family);
            if (id == 0)
                rb_str_catf(ret, "unknown address family %d", rai->addr.ss_family);
            else
                rb_str_catf(ret, "%s address format unknown", rb_id2name(id));
            break;
          }
        }
    }

    if (rai->pfamily && ai_get_afamily(rai) != rai->pfamily) {
        ID id = intern_protocol_family(rai->pfamily);
        if (id)
            rb_str_catf(ret, " %s", rb_id2name(id));
        else
            rb_str_catf(ret, " PF_\?\?\?(%d)", rai->pfamily);
    }

    internet_p = rai->pfamily == PF_INET;
#ifdef INET6
    internet_p = internet_p || rai->pfamily == PF_INET6;
#endif
    if (internet_p && rai->socktype == SOCK_STREAM &&
        (rai->protocol == 0 || rai->protocol == IPPROTO_TCP)) {
        rb_str_cat2(ret, " TCP");
    }
    else if (internet_p && rai->socktype == SOCK_DGRAM &&
        (rai->protocol == 0 || rai->protocol == IPPROTO_UDP)) {
        rb_str_cat2(ret, " UDP");
    }
    else {
        if (rai->socktype) {
            ID id = intern_socktype(rai->socktype);
            if (id)
                rb_str_catf(ret, " %s", rb_id2name(id));
            else
                rb_str_catf(ret, " SOCK_\?\?\?(%d)", rai->socktype);
        }

        if (rai->protocol) {
            if (internet_p) {
                ID id = intern_ipproto(rai->protocol);
                if (id)
                    rb_str_catf(ret, " %s", rb_id2name(id));
                else
                    goto unknown_protocol;
            }
            else {
              unknown_protocol:
                rb_str_catf(ret, " UNKNOWN_PROTOCOL(%d)", rai->protocol);
            }
        }
    }

    if (!NIL_P(rai->canonname)) {
        VALUE name = rai->canonname;
        rb_str_catf(ret, " %s", StringValueCStr(name));
    }

    if (!NIL_P(rai->inspectname)) {
        VALUE name = rai->inspectname;
        rb_str_catf(ret, " (%s)", StringValueCStr(name));
    }

    rb_str_buf_cat2(ret, ">");
    return ret;
}

/*
 * call-seq:
 *   addrinfo.afamily => integer
 *
 * returns the address family as an integer.
 *
 *   AddrInfo.tcp("localhost", 80).afamily == Socket::AF_INET #=> true
 *
 */
static VALUE
addrinfo_afamily(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    return INT2NUM(ai_get_afamily(rai));
}

/*
 * call-seq:
 *   addrinfo.pfamily => integer
 *
 * returns the protocol family as an integer.
 *
 *   AddrInfo.tcp("localhost", 80).pfamily == Socket::PF_INET #=> true
 *
 */
static VALUE
addrinfo_pfamily(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    return INT2NUM(rai->pfamily);
}

/*
 * call-seq:
 *   addrinfo.socktype => integer
 *
 * returns the socket type as an integer.
 *
 *   AddrInfo.tcp("localhost", 80).socktype == Socket::SOCK_STREAM #=> true
 *
 */
static VALUE
addrinfo_socktype(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    return INT2NUM(rai->socktype);
}

/*
 * call-seq:
 *   addrinfo.protocol => integer
 *
 * returns the socket type as an integer.
 *
 *   AddrInfo.tcp("localhost", 80).protocol == Socket::IPPROTO_TCP #=> true
 *
 */
static VALUE
addrinfo_protocol(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    return INT2NUM(rai->protocol);
}

/*
 * call-seq:
 *   addrinfo.to_sockaddr => string
 *
 * returns the socket address as packed struct sockaddr string.
 *
 *   AddrInfo.tcp("localhost", 80).to_sockaddr                    
 *   #=> "\x02\x00\x00P\x7F\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00"
 *
 */
static VALUE
addrinfo_to_sockaddr(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    VALUE ret;
    ret = rb_str_new((char*)&rai->addr, rai->sockaddr_len);
    OBJ_INFECT(ret, self);
    return ret;
}

/*
 * call-seq:
 *   addrinfo.canonname => string or nil
 *
 * returns the canonical name as an string.
 *
 * nil is returned if no canonical name.
 *
 * The canonical name is set by AddrInfo.getaddrinfo when AI_CANONNAME is specified.
 *
 *   list = AddrInfo.getaddrinfo("www.ruby-lang.org", 80, :INET, :STREAM, nil, Socket::AI_CANONNAME)
 *   p list[0] #=> #<AddrInfo: 221.186.184.68:80 TCP carbon.ruby-lang.org (www.ruby-lang.org:80)>
 *   p list[0].canonname #=> "carbon.ruby-lang.org"
 *
 */
static VALUE
addrinfo_canonname(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    return rai->canonname;
}

/*
 * call-seq:
 *   addrinfo.ip? => true or false
 *
 * returns true if addrinfo is internet (IPv4/IPv6) address.
 * returns false otherwise.
 *
 *   AddrInfo.tcp("127.0.0.1", 80).ip? #=> true
 *   AddrInfo.tcp("::1", 80).ip?       #=> true
 *   AddrInfo.unix("/tmp/sock").ip?    #=> false
 *
 */
static VALUE
addrinfo_ip_p(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    int family = ai_get_afamily(rai);
    return family == AF_INET
#ifdef AF_INET6
        || family == AF_INET6
#endif
        ? Qtrue : Qfalse;
    return Qfalse;
}

/*
 * call-seq:
 *   addrinfo.ipv4? => true or false
 *
 * returns true if addrinfo is IPv4 address.
 * returns false otherwise.
 *
 *   AddrInfo.tcp("127.0.0.1", 80).ipv4? #=> true
 *   AddrInfo.tcp("::1", 80).ipv4?       #=> false
 *   AddrInfo.unix("/tmp/sock").ipv4?    #=> false
 *
 */
static VALUE
addrinfo_ipv4_p(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    return ai_get_afamily(rai) == AF_INET ? Qtrue : Qfalse;
}

/*
 * call-seq:
 *   addrinfo.ipv6? => true or false
 *
 * returns true if addrinfo is IPv6 address.
 * returns false otherwise.
 *
 *   AddrInfo.tcp("127.0.0.1", 80).ipv6? #=> false
 *   AddrInfo.tcp("::1", 80).ipv6?       #=> true
 *   AddrInfo.unix("/tmp/sock").ipv6?    #=> false
 *
 */
static VALUE
addrinfo_ipv6_p(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
#ifdef AF_INET6
    return ai_get_afamily(rai) == AF_INET6 ? Qtrue : Qfalse;
#else
    return Qfalse;
#endif
}

/*
 * call-seq:
 *   addrinfo.unix? => true or false
 *
 * returns true if addrinfo is UNIX address.
 * returns false otherwise.
 *
 *   AddrInfo.tcp("127.0.0.1", 80).unix? #=> false
 *   AddrInfo.tcp("::1", 80).unix?       #=> false
 *   AddrInfo.unix("/tmp/sock").unix?    #=> true
 *
 */
static VALUE
addrinfo_unix_p(VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
#ifdef AF_UNIX
    return ai_get_afamily(rai) == AF_UNIX ? Qtrue : Qfalse;
#else
    return Qfalse;
#endif
}

/*
 * call-seq:
 *   addrinfo.getnameinfo        => [nodename, service]
 *   addrinfo.getnameinfo(flags) => [nodename, service]
 *
 * returns nodename and service as a pair of strings.
 * This converts struct sockaddr in addrinfo to textual representation.
 *
 * flags should be bitwise OR of Socket::NI_??? constants.
 *
 *   AddrInfo.tcp("127.0.0.1", 80).getnameinfo #=> ["localhost", "www"]
 *
 *   AddrInfo.tcp("127.0.0.1", 80).getnameinfo(Socket::NI_NUMERICSERV)
 *   #=> ["localhost", "80"]
 */
static VALUE
addrinfo_getnameinfo(int argc, VALUE *argv, VALUE self)
{
    rb_addrinfo_t *rai = get_addrinfo(self);
    VALUE vflags;
    char hbuf[1024], pbuf[1024];
    int flags, error;

    rb_scan_args(argc, argv, "01", &vflags);

    flags = NIL_P(vflags) ? 0 : NUM2INT(vflags);

    if (rai->socktype == SOCK_DGRAM)
        flags |= NI_DGRAM;

    error = getnameinfo((struct sockaddr *)&rai->addr, rai->sockaddr_len,
                        hbuf, sizeof(hbuf), pbuf, sizeof(pbuf),
                        flags);
    if (error) {
        raise_socket_error("getnameinfo", error);
    }

    return rb_assoc_new(rb_str_new2(hbuf), rb_str_new2(pbuf));
}

/*
 * call-seq:
 *   AddrInfo.getaddrinfo(nodename, service, family, socktype, protocol, flags) => [addrinfo, ...]
 *   AddrInfo.getaddrinfo(nodename, service, family, socktype, protocol)        => [addrinfo, ...]
 *   AddrInfo.getaddrinfo(nodename, service, family, socktype)                  => [addrinfo, ...]
 *   AddrInfo.getaddrinfo(nodename, service, family)                            => [addrinfo, ...]
 *   AddrInfo.getaddrinfo(nodename, service)                                    => [addrinfo, ...]
 *
 * returns a list of addrinfo objects as an array.
 *
 * This method converts nodename (hostname) and service (port) to addrinfo.
 * Since the conversion is not unique, the result is a list of addrinfo objects.
 *
 * nodename or service can be nil if no conversion intended.
 *
 * family, socktype and protocol are hint for prefered protocol.
 * If the result will be used for a socket with SOCK_STREAM, 
 * SOCK_STREAM should be specified as socktype.
 * If so, AddrInfo.getaddrinfo returns addrinfo list appropriate for SOCK_STREAM.
 * If they are omitted or nil is given, the result is not restricted.
 * 
 * Similary, PF_INET6 as family restricts for IPv6.
 *
 * flags should be bitwise OR of Socket::AI_??? constants.
 *
 *   AddrInfo.getaddrinfo("www.kame.net", 80, nil, :STREAM)
 *   #=> [#<AddrInfo: 203.178.141.194:80 TCP (www.kame.net:80)>,
 *   #    #<AddrInfo: [2001:200:0:8002:203:47ff:fea5:3085]:80 TCP (www.kame.net:80)>]
 *
 */
static VALUE
addrinfo_s_getaddrinfo(int argc, VALUE *argv, VALUE self)
{
    VALUE node, service, family, socktype, protocol, flags;

    rb_scan_args(argc, argv, "24", &node, &service, &family, &socktype, &protocol, &flags);
    return addrinfo_list_new(node, service, family, socktype, protocol, flags);
}


/*
 * call-seq:
 *   AddrInfo.tcp(host, port) => addrinfo
 *
 * returns an addrinfo object for TCP address.
 *
 *   AddrInfo.tcp("localhost", "smtp") #=> #<AddrInfo: 127.0.0.1:25 TCP (localhost:smtp)>
 */
static VALUE
addrinfo_s_tcp(VALUE self, VALUE host, VALUE port)
{
    return addrinfo_firstonly_new(host, port,
            INT2NUM(PF_UNSPEC), INT2NUM(SOCK_STREAM), INT2FIX(IPPROTO_TCP), INT2FIX(0));
}

/*
 * call-seq:
 *   AddrInfo.udp(host, port) => addrinfo
 *
 * returns an addrinfo object for UDP address.
 *
 *   AddrInfo.udp("localhost", "daytime") #=> #<AddrInfo: 127.0.0.1:13 UDP (localhost:daytime)>
 */
static VALUE
addrinfo_s_udp(VALUE self, VALUE host, VALUE port)
{
    return addrinfo_firstonly_new(host, port,
            INT2NUM(PF_UNSPEC), INT2NUM(SOCK_DGRAM), INT2FIX(IPPROTO_UDP), INT2FIX(0));
}

#ifdef HAVE_SYS_UN_H

/*
 * call-seq:
 *   AddrInfo.udp(host, port) => addrinfo
 *
 * returns an addrinfo object for UNIX socket address.
 *
 *   AddrInfo.unix("/tmp/sock") #=> #<AddrInfo: /tmp/sock SOCK_STREAM>
 */
static VALUE
addrinfo_s_unix(VALUE self, VALUE path)
{
    VALUE addr;
    rb_addrinfo_t *rai;

    addr = addrinfo_s_allocate(rb_cAddrInfo);
    DATA_PTR(addr) = rai = alloc_addrinfo();
    init_unix_addrinfo(rai, path);
    OBJ_INFECT(addr, path);
    return addr;
}

#endif

static VALUE
sockaddr_string_value(volatile VALUE *v)
{
    VALUE val = *v;
    if (TYPE(val) == RUBY_T_DATA && IS_ADDRINFO(val)) {
        *v = addrinfo_to_sockaddr(val);
    }
    StringValue(*v);
    return *v;
}

static char *
sockaddr_string_value_ptr(volatile VALUE *v)
{
    sockaddr_string_value(v);
    return RSTRING_PTR(*v);
}

static void
sock_define_const(const char *name, int value, VALUE mConst)
{
    rb_define_const(rb_cSocket, name, INT2NUM(value));
    rb_define_const(mConst, name, INT2NUM(value));
}

static void
sock_define_uconst(const char *name, unsigned int value, VALUE mConst)
{
    rb_define_const(rb_cSocket, name, UINT2NUM(value));
    rb_define_const(mConst, name, UINT2NUM(value));
}

/*
 * Class +Socket+ provides access to the underlying operating system
 * socket implementations. It can be used to provide more operating system
 * specific functionality than the protocol-specific socket classes but at the
 * expense of greater complexity. In particular, the class handles addresses
 * using +struct+ sockaddr structures packed into Ruby strings, which can be
 * a joy to manipulate.
 * 
 * === Exception Handling
 * Ruby's implementation of +Socket+ causes an exception to be raised
 * based on the error generated by the system dependent implementation.
 * This is why the methods are documented in a way that isolate
 * Unix-based system exceptions from Windows based exceptions. If more
 * information on particular exception is needed please refer to the 
 * Unix manual pages or the Windows WinSock reference.
 * 
 * 
 * === Documentation by
 * * Zach Dennis
 * * Sam Roberts
 * * <em>Programming Ruby</em> from The Pragmatic Bookshelf.  
 * 
 * Much material in this documentation is taken with permission from  
 * <em>Programming Ruby</em> from The Pragmatic Bookshelf.  
 */
void
Init_socket()
{
    VALUE mConst;

    rb_eSocket = rb_define_class("SocketError", rb_eStandardError);

    rb_cBasicSocket = rb_define_class("BasicSocket", rb_cIO);
    rb_undef_method(rb_cBasicSocket, "initialize");

    rb_define_singleton_method(rb_cBasicSocket, "do_not_reverse_lookup",
			       bsock_do_not_rev_lookup, 0);
    rb_define_singleton_method(rb_cBasicSocket, "do_not_reverse_lookup=",
			       bsock_do_not_rev_lookup_set, 1);
    rb_define_singleton_method(rb_cBasicSocket, "for_fd", bsock_s_for_fd, 1);

    rb_define_method(rb_cBasicSocket, "close_read", bsock_close_read, 0);
    rb_define_method(rb_cBasicSocket, "close_write", bsock_close_write, 0);
    rb_define_method(rb_cBasicSocket, "shutdown", bsock_shutdown, -1);
    rb_define_method(rb_cBasicSocket, "setsockopt", bsock_setsockopt, 3);
    rb_define_method(rb_cBasicSocket, "getsockopt", bsock_getsockopt, 2);
    rb_define_method(rb_cBasicSocket, "getsockname", bsock_getsockname, 0);
    rb_define_method(rb_cBasicSocket, "getpeername", bsock_getpeername, 0);
    rb_define_method(rb_cBasicSocket, "local_address", bsock_local_address, 0);
    rb_define_method(rb_cBasicSocket, "remote_address", bsock_remote_address, 0);
    rb_define_method(rb_cBasicSocket, "send", bsock_send, -1);
    rb_define_method(rb_cBasicSocket, "recv", bsock_recv, -1);
    rb_define_method(rb_cBasicSocket, "recv_nonblock", bsock_recv_nonblock, -1);
    rb_define_method(rb_cBasicSocket, "do_not_reverse_lookup", bsock_do_not_reverse_lookup, 0);
    rb_define_method(rb_cBasicSocket, "do_not_reverse_lookup=", bsock_do_not_reverse_lookup_set, 1);

    rb_cIPSocket = rb_define_class("IPSocket", rb_cBasicSocket);
    rb_define_method(rb_cIPSocket, "addr", ip_addr, 0);
    rb_define_method(rb_cIPSocket, "peeraddr", ip_peeraddr, 0);
    rb_define_method(rb_cIPSocket, "recvfrom", ip_recvfrom, -1);
    rb_define_singleton_method(rb_cIPSocket, "getaddress", ip_s_getaddress, 1);

    rb_cTCPSocket = rb_define_class("TCPSocket", rb_cIPSocket);
    rb_define_singleton_method(rb_cTCPSocket, "gethostbyname", tcp_s_gethostbyname, 1);
    rb_define_method(rb_cTCPSocket, "initialize", tcp_init, -1);

#ifdef SOCKS
    rb_cSOCKSSocket = rb_define_class("SOCKSSocket", rb_cTCPSocket);
    rb_define_method(rb_cSOCKSSocket, "initialize", socks_init, 2);
#ifdef SOCKS5
    rb_define_method(rb_cSOCKSSocket, "close", socks_s_close, 0);
#endif
#endif

    rb_cTCPServer = rb_define_class("TCPServer", rb_cTCPSocket);
    rb_define_method(rb_cTCPServer, "accept", tcp_accept, 0);
    rb_define_method(rb_cTCPServer, "accept_nonblock", tcp_accept_nonblock, 0);
    rb_define_method(rb_cTCPServer, "sysaccept", tcp_sysaccept, 0);
    rb_define_method(rb_cTCPServer, "initialize", tcp_svr_init, -1);
    rb_define_method(rb_cTCPServer, "listen", sock_listen, 1);

    rb_cUDPSocket = rb_define_class("UDPSocket", rb_cIPSocket);
    rb_define_method(rb_cUDPSocket, "initialize", udp_init, -1);
    rb_define_method(rb_cUDPSocket, "connect", udp_connect, 2);
    rb_define_method(rb_cUDPSocket, "bind", udp_bind, 2);
    rb_define_method(rb_cUDPSocket, "send", udp_send, -1);
    rb_define_method(rb_cUDPSocket, "recvfrom_nonblock", udp_recvfrom_nonblock, -1);

#ifdef HAVE_SYS_UN_H
    rb_cUNIXSocket = rb_define_class("UNIXSocket", rb_cBasicSocket);
    rb_define_method(rb_cUNIXSocket, "initialize", unix_init, 1);
    rb_define_method(rb_cUNIXSocket, "path", unix_path, 0);
    rb_define_method(rb_cUNIXSocket, "addr", unix_addr, 0);
    rb_define_method(rb_cUNIXSocket, "peeraddr", unix_peeraddr, 0);
    rb_define_method(rb_cUNIXSocket, "recvfrom", unix_recvfrom, -1);
    rb_define_method(rb_cUNIXSocket, "send_io", unix_send_io, 1);
    rb_define_method(rb_cUNIXSocket, "recv_io", unix_recv_io, -1);
    rb_define_singleton_method(rb_cUNIXSocket, "socketpair", unix_s_socketpair, -1);
    rb_define_singleton_method(rb_cUNIXSocket, "pair", unix_s_socketpair, -1);

    rb_cUNIXServer = rb_define_class("UNIXServer", rb_cUNIXSocket);
    rb_define_method(rb_cUNIXServer, "initialize", unix_svr_init, 1);
    rb_define_method(rb_cUNIXServer, "accept", unix_accept, 0);
    rb_define_method(rb_cUNIXServer, "accept_nonblock", unix_accept_nonblock, 0);
    rb_define_method(rb_cUNIXServer, "sysaccept", unix_sysaccept, 0);
    rb_define_method(rb_cUNIXServer, "listen", sock_listen, 1);
#endif

    rb_cSocket = rb_define_class("Socket", rb_cBasicSocket);

    rb_define_method(rb_cSocket, "initialize", sock_initialize, 3);
    rb_define_method(rb_cSocket, "connect", sock_connect, 1);
    rb_define_method(rb_cSocket, "connect_nonblock", sock_connect_nonblock, 1);
    rb_define_method(rb_cSocket, "bind", sock_bind, 1);
    rb_define_method(rb_cSocket, "listen", sock_listen, 1);
    rb_define_method(rb_cSocket, "accept", sock_accept, 0);
    rb_define_method(rb_cSocket, "accept_nonblock", sock_accept_nonblock, 0);
    rb_define_method(rb_cSocket, "sysaccept", sock_sysaccept, 0);

    rb_define_method(rb_cSocket, "recvfrom", sock_recvfrom, -1);
    rb_define_method(rb_cSocket, "recvfrom_nonblock", sock_recvfrom_nonblock, -1);

    rb_define_singleton_method(rb_cSocket, "socketpair", sock_s_socketpair, 3);
    rb_define_singleton_method(rb_cSocket, "pair", sock_s_socketpair, 3);
    rb_define_singleton_method(rb_cSocket, "gethostname", sock_gethostname, 0);
    rb_define_singleton_method(rb_cSocket, "gethostbyname", sock_s_gethostbyname, 1);
    rb_define_singleton_method(rb_cSocket, "gethostbyaddr", sock_s_gethostbyaddr, -1);
    rb_define_singleton_method(rb_cSocket, "getservbyname", sock_s_getservbyname, -1);
    rb_define_singleton_method(rb_cSocket, "getservbyport", sock_s_getservbyport, -1);
    rb_define_singleton_method(rb_cSocket, "getaddrinfo", sock_s_getaddrinfo, -1);
    rb_define_singleton_method(rb_cSocket, "getnameinfo", sock_s_getnameinfo, -1);
    rb_define_singleton_method(rb_cSocket, "sockaddr_in", sock_s_pack_sockaddr_in, 2);
    rb_define_singleton_method(rb_cSocket, "pack_sockaddr_in", sock_s_pack_sockaddr_in, 2);
    rb_define_singleton_method(rb_cSocket, "unpack_sockaddr_in", sock_s_unpack_sockaddr_in, 1);
#ifdef HAVE_SYS_UN_H
    rb_define_singleton_method(rb_cSocket, "sockaddr_un", sock_s_pack_sockaddr_un, 1);
    rb_define_singleton_method(rb_cSocket, "pack_sockaddr_un", sock_s_pack_sockaddr_un, 1);
    rb_define_singleton_method(rb_cSocket, "unpack_sockaddr_un", sock_s_unpack_sockaddr_un, 1);
#endif

    rb_cAddrInfo = rb_define_class("AddrInfo", rb_cData);
    rb_define_alloc_func(rb_cAddrInfo, addrinfo_s_allocate);
    rb_define_method(rb_cAddrInfo, "initialize", addrinfo_initialize, -1);
    rb_define_method(rb_cAddrInfo, "inspect", addrinfo_inspect, 0);
    rb_define_singleton_method(rb_cAddrInfo, "getaddrinfo", addrinfo_s_getaddrinfo, -1);
    rb_define_singleton_method(rb_cAddrInfo, "tcp", addrinfo_s_tcp, 2);
    rb_define_singleton_method(rb_cAddrInfo, "udp", addrinfo_s_udp, 2);
#ifdef HAVE_SYS_UN_H
    rb_define_singleton_method(rb_cAddrInfo, "unix", addrinfo_s_unix, 1);
#endif

    rb_define_method(rb_cAddrInfo, "afamily", addrinfo_afamily, 0);
    rb_define_method(rb_cAddrInfo, "pfamily", addrinfo_pfamily, 0);
    rb_define_method(rb_cAddrInfo, "socktype", addrinfo_socktype, 0);
    rb_define_method(rb_cAddrInfo, "protocol", addrinfo_protocol, 0);
    rb_define_method(rb_cAddrInfo, "canonname", addrinfo_canonname, 0);

    rb_define_method(rb_cAddrInfo, "ip?",   addrinfo_ip_p, 0);
    rb_define_method(rb_cAddrInfo, "ipv4?", addrinfo_ipv4_p, 0);
    rb_define_method(rb_cAddrInfo, "ipv6?", addrinfo_ipv6_p, 0);
    rb_define_method(rb_cAddrInfo, "unix?", addrinfo_unix_p, 0);

    rb_define_method(rb_cAddrInfo, "to_sockaddr", addrinfo_to_sockaddr, 0);

    rb_define_method(rb_cAddrInfo, "getnameinfo", addrinfo_getnameinfo, -1);

    /* constants */
    mConst = rb_define_module_under(rb_cSocket, "Constants");
    init_constants(mConst);
}