summaryrefslogtreecommitdiff
path: root/ext/socket/ancdata.c
blob: b2c246260df8d0bb668e40022df36b95d099165f (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
#include "rubysocket.h"

#if defined(HAVE_ST_MSG_CONTROL)
static VALUE rb_cAncillaryData;

static VALUE
constant_to_sym(int constant, ID (*intern_const)(int))
{
    ID name = intern_const(constant);
    if (name) {
        return ID2SYM(name);
    }

    return INT2NUM(constant);
}

static VALUE
ip_cmsg_type_to_sym(int level, int cmsg_type)
{
    switch (level) {
      case SOL_SOCKET:
        return constant_to_sym(cmsg_type, intern_scm_optname);
      case IPPROTO_IP:
        return constant_to_sym(cmsg_type, intern_ip_optname);
#ifdef IPPROTO_IPV6
      case IPPROTO_IPV6:
        return constant_to_sym(cmsg_type, intern_ipv6_optname);
#endif
      case IPPROTO_TCP:
        return constant_to_sym(cmsg_type, intern_tcp_optname);
      case IPPROTO_UDP:
        return constant_to_sym(cmsg_type, intern_udp_optname);
      default:
        return INT2NUM(cmsg_type);
    }
}

/*
 * call-seq:
 *   Socket::AncillaryData.new(family, cmsg_level, cmsg_type, cmsg_data) -> ancillarydata
 *
 * _family_ should be an integer, a string or a symbol.
 * - Socket::AF_INET, "AF_INET", "INET", :AF_INET, :INET
 * - Socket::AF_UNIX, "AF_UNIX", "UNIX", :AF_UNIX, :UNIX
 * - etc.
 *
 * _cmsg_level_ should be an integer, a string or a symbol.
 * - Socket::SOL_SOCKET, "SOL_SOCKET", "SOCKET", :SOL_SOCKET and :SOCKET
 * - Socket::IPPROTO_IP, "IP" and :IP
 * - Socket::IPPROTO_IPV6, "IPV6" and :IPV6
 * - Socket::IPPROTO_TCP, "TCP" and :TCP
 * - etc.
 *
 * _cmsg_type_ should be an integer, a string or a symbol.
 * If a string/symbol is specified, it is interepreted depend on _cmsg_level_.
 * - Socket::SCM_RIGHTS, "SCM_RIGHTS", "RIGHTS", :SCM_RIGHTS, :RIGHTS for SOL_SOCKET
 * - Socket::IP_RECVTTL, "RECVTTL" and :RECVTTL for IPPROTO_IP
 * - Socket::IPV6_PKTINFO, "PKTINFO" and :PKTINFO for IPPROTO_IPV6
 * - etc.
 *
 * _cmsg_data_ should be a string.
 *
 *   p Socket::AncillaryData.new(:INET, :TCP, :NODELAY, "")
 *   #=> #<Socket::AncillaryData: INET TCP NODELAY "">
 *
 *   p Socket::AncillaryData.new(:INET6, :IPV6, :PKTINFO, "")     
 *   #=> #<Socket::AncillaryData: INET6 IPV6 PKTINFO "">
 *
 */
static VALUE
ancillary_initialize(VALUE self, VALUE vfamily, VALUE vlevel, VALUE vtype, VALUE data)
{
    int family = family_arg(vfamily);
    int level = level_arg(family, vlevel);
    int type = cmsg_type_arg(family, level, vtype);
    StringValue(data);
    rb_ivar_set(self, rb_intern("family"), INT2NUM(family));
    rb_ivar_set(self, rb_intern("level"), INT2NUM(level));
    rb_ivar_set(self, rb_intern("type"), INT2NUM(type));
    rb_ivar_set(self, rb_intern("data"), data);
    return self;
}

static VALUE
ancdata_new(int family, int level, int type, VALUE data)
{
    NEWOBJ(obj, struct RObject);
    OBJSETUP(obj, rb_cAncillaryData, T_OBJECT);
    StringValue(data);
    ancillary_initialize((VALUE)obj, INT2NUM(family), INT2NUM(level), INT2NUM(type), data);
    return (VALUE)obj;
}

static int
ancillary_family(VALUE self)
{
    VALUE v = rb_attr_get(self, rb_intern("family"));
    return NUM2INT(v);
}

/*
 * call-seq:
 *   ancillarydata.family => integer
 *
 * returns the socket family as an integer.
 *
 *   p Socket::AncillaryData.new(:INET6, :IPV6, :PKTINFO, "").family
 *   #=> 10
 */
static VALUE
ancillary_family_m(VALUE self)
{
    return INT2NUM(ancillary_family(self));
}

static int
ancillary_level(VALUE self)
{
    VALUE v = rb_attr_get(self, rb_intern("level"));
    return NUM2INT(v);
}

/*
 * call-seq:
 *   ancillarydata.level => integer
 *
 * returns the cmsg level as an integer.
 *
 *   p Socket::AncillaryData.new(:INET6, :IPV6, :PKTINFO, "").level
 *   #=> 41
 */
static VALUE
ancillary_level_m(VALUE self)
{
    return INT2NUM(ancillary_level(self));
}

static int
ancillary_type(VALUE self)
{
    VALUE v = rb_attr_get(self, rb_intern("type"));
    return NUM2INT(v);
}

/*
 * call-seq:
 *   ancillarydata.type => integer
 *
 * returns the cmsg type as an integer.
 *
 *   p Socket::AncillaryData.new(:INET6, :IPV6, :PKTINFO, "").type
 *   #=> 2
 */
static VALUE
ancillary_type_m(VALUE self)
{
    return INT2NUM(ancillary_type(self));
}

/*
 * call-seq:
 *   ancillarydata.data => string
 *
 * returns the cmsg data as a string.
 *
 *   p Socket::AncillaryData.new(:INET6, :IPV6, :PKTINFO, "").data
 *   #=> ""
 */
static VALUE
ancillary_data(VALUE self)
{
    VALUE v = rb_attr_get(self, rb_intern("data"));
    StringValue(v);
    return v;
}


/*
 * call-seq:
 *   Socket::AncillaryData.int(family, cmsg_level, cmsg_type, integer) => ancillarydata
 *
 * Creates a new Socket::AncillaryData object which contains a int as data.
 *
 * The size and endian is dependent on the host. 
 *
 *   p Socket::AncillaryData.int(:UNIX, :SOCKET, :RIGHTS, STDERR.fileno)
 *   #=> #<Socket::AncillaryData: UNIX SOCKET RIGHTS 2>
 */
static VALUE
ancillary_s_int(VALUE klass, VALUE vfamily, VALUE vlevel, VALUE vtype, VALUE integer)
{
    int family = family_arg(vfamily);
    int level = level_arg(family, vlevel);
    int type = cmsg_type_arg(family, level, vtype);
    int i = NUM2INT(integer);
    return ancdata_new(family, level, type, rb_str_new((char*)&i, sizeof(i)));
}

/*
 * call-seq:
 *   ancillarydata.int => integer
 *
 * Returns the data in _ancillarydata_ as an int.
 *
 * The size and endian is dependent on the host. 
 *
 *   ancdata = Socket::AncillaryData.int(:UNIX, :SOCKET, :RIGHTS, STDERR.fileno)
 *   p ancdata.int #=> 2
 */
static VALUE
ancillary_int(VALUE self)
{
    VALUE data;
    int i;
    data = ancillary_data(self);
    if (RSTRING_LEN(data) != sizeof(int))
        rb_raise(rb_eTypeError, "size differ.  expected as sizeof(int)=%d but %ld", (int)sizeof(int), (long)RSTRING_LEN(data));
    memcpy((char*)&i, RSTRING_PTR(data), sizeof(int));
    return INT2NUM(i);
}

/*
 * call-seq:
 *   Socket::AncillaryData.ip_pktinfo(addr, ifindex) => ancdata
 *   Socket::AncillaryData.ip_pktinfo(addr, ifindex, spec_dst) => ancdata
 *
 * Returns new ancillary data for IP_PKTINFO.
 *
 * If spec_dst is not given, addr is used.
 *
 * IP_PKTINFO is not standard.
 *
 * Supported platform: GNU/Linux
 *
 *   addr = Addrinfo.ip("127.0.0.1")
 *   ifindex = 0
 *   spec_dst = Addrinfo.ip("127.0.0.1")
 *   p Socket::AncillaryData.ip_pktinfo(addr, ifindex, spec_dst)
 *   #=> #<Socket::AncillaryData: INET IP PKTINFO 127.0.0.1 ifindex:0 spec_dst:127.0.0.1>
 *
 */
static VALUE
ancillary_s_ip_pktinfo(int argc, VALUE *argv, VALUE self)
{
#if defined(IPPROTO_IP) && defined(IP_PKTINFO) && defined(HAVE_TYPE_STRUCT_IN_PKTINFO) /* GNU/Linux */
    VALUE v_addr, v_ifindex, v_spec_dst;
    unsigned int ifindex;
    struct sockaddr_in sa;
    struct in_pktinfo pktinfo;

    rb_scan_args(argc, argv, "21", &v_addr, &v_ifindex, &v_spec_dst);

    SockAddrStringValue(v_addr);
    ifindex = NUM2UINT(v_ifindex);
    if (NIL_P(v_spec_dst))
        v_spec_dst = v_addr;
    else
        SockAddrStringValue(v_spec_dst);

    memset(&pktinfo, 0, sizeof(pktinfo));

    memset(&sa, 0, sizeof(sa));
    if (RSTRING_LEN(v_addr) != sizeof(sa))
        rb_raise(rb_eArgError, "addr size different to AF_INET sockaddr");
    memcpy(&sa, RSTRING_PTR(v_addr), sizeof(sa));
    if (sa.sin_family != AF_INET)
        rb_raise(rb_eArgError, "addr is not AF_INET sockaddr");
    memcpy(&pktinfo.ipi_addr, &sa.sin_addr, sizeof(pktinfo.ipi_addr));

    pktinfo.ipi_ifindex = ifindex;

    memset(&sa, 0, sizeof(sa));
    if (RSTRING_LEN(v_spec_dst) != sizeof(sa))
        rb_raise(rb_eArgError, "spec_dat size different to AF_INET sockaddr");
    memcpy(&sa, RSTRING_PTR(v_spec_dst), sizeof(sa));
    if (sa.sin_family != AF_INET)
        rb_raise(rb_eArgError, "spec_dst is not AF_INET sockaddr");
    memcpy(&pktinfo.ipi_spec_dst, &sa.sin_addr, sizeof(pktinfo.ipi_spec_dst));

    return ancdata_new(AF_INET, IPPROTO_IP, IP_PKTINFO, rb_str_new((char *)&pktinfo, sizeof(pktinfo)));
#else
    rb_notimplement();
#endif
}

/*
 * call-seq:
 *   ancdata.ip_pktinfo => [addr, ifindex, spec_dst]
 *
 * Extracts addr, ifindex and spec_dst from IP_PKTINFO ancillary data.
 *
 * IP_PKTINFO is not standard.
 *
 * Supported platform: GNU/Linux
 *
 *   addr = Addrinfo.ip("127.0.0.1")
 *   ifindex = 0
 *   spec_dest = Addrinfo.ip("127.0.0.1")
 *   ancdata = Socket::AncillaryData.ip_pktinfo(addr, ifindex, spec_dest)
 *   p ancdata.ip_pktinfo
 *   #=> [#<Addrinfo: 127.0.0.1>, 0, #<Addrinfo: 127.0.0.1>]
 *
 *
 */
static VALUE
ancillary_ip_pktinfo(VALUE self)
{
#if defined(IPPROTO_IP) && defined(IP_PKTINFO) && defined(HAVE_TYPE_STRUCT_IN_PKTINFO) /* GNU/Linux */
    int level, type;
    VALUE data;
    struct in_pktinfo pktinfo;
    struct sockaddr_in sa;
    VALUE v_spec_dst, v_addr;

    level = ancillary_level(self);
    type = ancillary_type(self);
    data = ancillary_data(self);

    if (level != IPPROTO_IP || type != IP_PKTINFO ||
        RSTRING_LEN(data) != sizeof(struct in_pktinfo)) {
        rb_raise(rb_eTypeError, "IP_PKTINFO ancillary data expected");
    }

    memcpy(&pktinfo, RSTRING_PTR(data), sizeof(struct in_pktinfo));
    memset(&sa, 0, sizeof(sa));

    sa.sin_family = AF_INET;
    memcpy(&sa.sin_addr, &pktinfo.ipi_addr, sizeof(sa.sin_addr));
    v_addr = addrinfo_new((struct sockaddr *)&sa, sizeof(sa), PF_INET, 0, 0, Qnil, Qnil);

    sa.sin_family = AF_INET;
    memcpy(&sa.sin_addr, &pktinfo.ipi_spec_dst, sizeof(sa.sin_addr));
    v_spec_dst = addrinfo_new((struct sockaddr *)&sa, sizeof(sa), PF_INET, 0, 0, Qnil, Qnil);

    return rb_ary_new3(3, v_addr, UINT2NUM(pktinfo.ipi_ifindex), v_spec_dst);
#else
    rb_notimplement();
#endif
}

/*
 * call-seq:
 *   Socket::AncillaryData.ipv6_pktinfo(addr, ifindex) => ancdata
 *
 * Returns new ancillary data for IPV6_PKTINFO.
 *
 * IPV6_PKTINFO is defined by RFC 3542.
 *
 *   addr = Addrinfo.ip("::1")
 *   ifindex = 0
 *   p Socket::AncillaryData.ipv6_pktinfo(addr, ifindex)
 *   #=> #<Socket::AncillaryData: INET6 IPV6 PKTINFO ::1 ifindex:0>
 *
 */
static VALUE
ancillary_s_ipv6_pktinfo(VALUE self, VALUE v_addr, VALUE v_ifindex)
{
#if defined(IPPROTO_IPV6) && defined(IPV6_PKTINFO) /* IPv6 RFC3542 */
    unsigned int ifindex;
    struct sockaddr_in6 sa;
    struct in6_pktinfo pktinfo;

    SockAddrStringValue(v_addr);
    ifindex = NUM2UINT(v_ifindex);

    memset(&pktinfo, 0, sizeof(pktinfo));

    memset(&sa, 0, sizeof(sa));
    if (RSTRING_LEN(v_addr) != sizeof(sa))
        rb_raise(rb_eArgError, "addr size different to AF_INET6 sockaddr");
    memcpy(&sa, RSTRING_PTR(v_addr), sizeof(sa));
    if (sa.sin6_family != AF_INET6)
        rb_raise(rb_eArgError, "addr is not AF_INET6 sockaddr");
    memcpy(&pktinfo.ipi6_addr, &sa.sin6_addr, sizeof(pktinfo.ipi6_addr));

    pktinfo.ipi6_ifindex = ifindex;

    return ancdata_new(AF_INET6, IPPROTO_IPV6, IPV6_PKTINFO, rb_str_new((char *)&pktinfo, sizeof(pktinfo)));
#else
    rb_notimplement();
#endif
}

#if defined(IPPROTO_IPV6) && defined(IPV6_PKTINFO) /* IPv6 RFC3542 */
static void
extract_ipv6_pktinfo(VALUE self, struct in6_pktinfo *pktinfo_ptr, struct sockaddr_in6 *sa_ptr)
{
    int level, type;
    VALUE data;

    level = ancillary_level(self);
    type = ancillary_type(self);
    data = ancillary_data(self);

    if (level != IPPROTO_IPV6 || type != IPV6_PKTINFO ||
        RSTRING_LEN(data) != sizeof(struct in6_pktinfo)) {
        rb_raise(rb_eTypeError, "IPV6_PKTINFO ancillary data expected");
    }

    memcpy(pktinfo_ptr, RSTRING_PTR(data), sizeof(*pktinfo_ptr));

    memset(sa_ptr, 0, sizeof(*sa_ptr));
    sa_ptr->sin6_family = AF_INET6;
    memcpy(&sa_ptr->sin6_addr, &pktinfo_ptr->ipi6_addr, sizeof(sa_ptr->sin6_addr));
    if (IN6_IS_ADDR_LINKLOCAL(&sa_ptr->sin6_addr))
        sa_ptr->sin6_scope_id = pktinfo_ptr->ipi6_ifindex;
}
#endif

/*
 * call-seq:
 *   ancdata.ipv6_pktinfo => [addr, ifindex]
 *
 * Extracts addr and ifindex from IPV6_PKTINFO ancillary data.
 *
 * IPV6_PKTINFO is defined by RFC 3542.
 *
 *   addr = Addrinfo.ip("::1")      
 *   ifindex = 0
 *   ancdata = Socket::AncillaryData.ipv6_pktinfo(addr, ifindex)
 *   p ancdata.ipv6_pktinfo #=> [#<Addrinfo: ::1>, 0]
 *
 */
static VALUE
ancillary_ipv6_pktinfo(VALUE self)
{
#if defined(IPPROTO_IPV6) && defined(IPV6_PKTINFO) /* IPv6 RFC3542 */
    struct in6_pktinfo pktinfo;
    struct sockaddr_in6 sa;
    VALUE v_addr;

    extract_ipv6_pktinfo(self, &pktinfo, &sa);
    v_addr = addrinfo_new((struct sockaddr *)&sa, sizeof(sa), PF_INET6, 0, 0, Qnil, Qnil);
    return rb_ary_new3(2, v_addr, UINT2NUM(pktinfo.ipi6_ifindex));
#else
    rb_notimplement();
#endif
}

/*
 * call-seq:
 *   ancdata.ipv6_pktinfo_addr => addr
 *
 * Extracts addr from IPV6_PKTINFO ancillary data.
 *
 * IPV6_PKTINFO is defined by RFC 3542.
 *
 *   addr = Addrinfo.ip("::1")
 *   ifindex = 0
 *   ancdata = Socket::AncillaryData.ipv6_pktinfo(addr, ifindex)
 *   p ancdata.ipv6_pktinfo_addr #=> #<Addrinfo: ::1>
 *
 */
static VALUE
ancillary_ipv6_pktinfo_addr(VALUE self)
{
#if defined(IPPROTO_IPV6) && defined(IPV6_PKTINFO) /* IPv6 RFC3542 */
    struct in6_pktinfo pktinfo;
    struct sockaddr_in6 sa;
    extract_ipv6_pktinfo(self, &pktinfo, &sa);
    return addrinfo_new((struct sockaddr *)&sa, sizeof(sa), PF_INET6, 0, 0, Qnil, Qnil);
#else
    rb_notimplement();
#endif
}

/*
 * call-seq:
 *   ancdata.ipv6_pktinfo_ifindex => addr
 *
 * Extracts ifindex from IPV6_PKTINFO ancillary data.
 *
 * IPV6_PKTINFO is defined by RFC 3542.
 *
 *   addr = Addrinfo.ip("::1")
 *   ifindex = 0
 *   ancdata = Socket::AncillaryData.ipv6_pktinfo(addr, ifindex)
 *   p ancdata.ipv6_pktinfo_ifindex #=> 0
 *
 */
static VALUE
ancillary_ipv6_pktinfo_ifindex(VALUE self)
{
#if defined(IPPROTO_IPV6) && defined(IPV6_PKTINFO) /* IPv6 RFC3542 */
    struct in6_pktinfo pktinfo;
    struct sockaddr_in6 sa;
    extract_ipv6_pktinfo(self, &pktinfo, &sa);
    return UINT2NUM(pktinfo.ipi6_ifindex);
#else
    rb_notimplement();
#endif
}

#if defined(SOL_SOCKET) && defined(SCM_RIGHTS) /* 4.4BSD */
static int
anc_inspect_socket_rights(int level, int type, VALUE data, VALUE ret)
{
    if (level == SOL_SOCKET && type == SCM_RIGHTS &&
        0 < RSTRING_LEN(data) && (RSTRING_LEN(data) % sizeof(int) == 0)) {
        long off;
        for (off = 0; off < RSTRING_LEN(data); off += sizeof(int)) {
            int fd;
            memcpy((char*)&fd, RSTRING_PTR(data)+off, sizeof(int));
            rb_str_catf(ret, " %d", fd);
        }
        return 1;
    }
    else {
        return 0;
    }
}
#endif

#if defined(SCM_CREDENTIALS) /* GNU/Linux */
static int
anc_inspect_passcred_credentials(int level, int type, VALUE data, VALUE ret)
{
    if (level == SOL_SOCKET && type == SCM_CREDENTIALS &&
        RSTRING_LEN(data) == sizeof(struct ucred)) {
        struct ucred cred;
        memcpy(&cred, RSTRING_PTR(data), sizeof(struct ucred));
        rb_str_catf(ret, " pid=%u uid=%u gid=%u", cred.pid, cred.uid, cred.gid);
	rb_str_cat2(ret, " (ucred)");
        return 1;
    }
    else {
        return 0;
    }
}
#endif

#if defined(SCM_CREDS)
#define INSPECT_SCM_CREDS
static int
anc_inspect_socket_creds(int level, int type, VALUE data, VALUE ret)
{
    if (level != SOL_SOCKET && type != SCM_CREDS)
	return 0;

    /*
     * FreeBSD has struct cmsgcred and struct sockcred.
     * They use both SOL_SOCKET/SCM_CREDS in the ancillary message.
     * They are not ambiguous from the view of the caller
     * because struct sockcred is sent if and only if the caller sets LOCAL_CREDS socket option.
     * But inspect method doesn't know it.
     * So they are ambiguous from the view of inspect.
     * This function distinguish them by the size of the ancillary message.
     * This heuristics works well except when sc_ngroups == CMGROUP_MAX.
     */

#if defined(HAVE_TYPE_STRUCT_CMSGCRED) /* FreeBSD */
    if (RSTRING_LEN(data) == sizeof(struct cmsgcred)) {
	struct cmsgcred cred;
        memcpy(&cred, RSTRING_PTR(data), sizeof(struct cmsgcred));
        rb_str_catf(ret, " pid=%u", cred.cmcred_pid);
        rb_str_catf(ret, " uid=%u", cred.cmcred_uid);
        rb_str_catf(ret, " euid=%u", cred.cmcred_euid);
        rb_str_catf(ret, " gid=%u", cred.cmcred_gid);
	if (cred.cmcred_ngroups) {
	    int i;
	    const char *sep = " groups=";
	    for (i = 0; i < cred.cmcred_ngroups; i++) {
		rb_str_catf(ret, "%s%u", sep, cred.cmcred_groups[i]);
		sep = ",";
	    }
	}
	rb_str_cat2(ret, " (cmsgcred)");
        return 1;
    }
#endif
#if defined(HAVE_TYPE_STRUCT_SOCKCRED) /* FreeBSD, NetBSD */
    if (RSTRING_LEN(data) >= SOCKCREDSIZE(0)) {
	struct sockcred cred0, *cred;
        memcpy(&cred0, RSTRING_PTR(data), SOCKCREDSIZE(0));
	if (RSTRING_LEN(data) == SOCKCREDSIZE(cred0.sc_ngroups)) {
	    cred = (struct sockcred *)ALLOCA_N(char, SOCKCREDSIZE(cred0.sc_ngroups));
	    memcpy(cred, RSTRING_PTR(data), SOCKCREDSIZE(cred0.sc_ngroups));
	    rb_str_catf(ret, " uid=%u", cred->sc_uid);
	    rb_str_catf(ret, " euid=%u", cred->sc_euid);
	    rb_str_catf(ret, " gid=%u", cred->sc_gid);
	    rb_str_catf(ret, " egid=%u", cred->sc_egid);
	    if (cred0.sc_ngroups) {
		int i;
		const char *sep = " groups=";
		for (i = 0; i < cred0.sc_ngroups; i++) {
		    rb_str_catf(ret, "%s%u", sep, cred->sc_groups[i]);
		    sep = ",";
		}
	    }
	    rb_str_cat2(ret, " (sockcred)");
	    return 1;
	}
    }
#endif
    return 0;
}
#endif

#if defined(IPPROTO_IP) && defined(IP_RECVDSTADDR) /* 4.4BSD */
static int
anc_inspect_ip_recvdstaddr(int level, int type, VALUE data, VALUE ret)
{
    if (level == IPPROTO_IP && type == IP_RECVDSTADDR &&
        RSTRING_LEN(data) == sizeof(struct in_addr)) {
        struct in_addr addr; 
        char addrbuf[INET_ADDRSTRLEN];
        memcpy(&addr, RSTRING_PTR(data), sizeof(addr));
        if (inet_ntop(AF_INET, &addr, addrbuf, sizeof(addrbuf)) == NULL)
            rb_str_cat2(ret, " invalid-address");
        else
            rb_str_catf(ret, " %s", addrbuf);
        return 1;
    }
    else {
        return 0;
    }
}
#endif

#if defined(IPPROTO_IP) && defined(IP_PKTINFO) && defined(HAVE_TYPE_STRUCT_IN_PKTINFO) /* GNU/Linux */
static int
anc_inspect_ip_pktinfo(int level, int type, VALUE data, VALUE ret)
{
    if (level == IPPROTO_IP && type == IP_PKTINFO &&
        RSTRING_LEN(data) == sizeof(struct in_pktinfo)) {
        struct in_pktinfo pktinfo;
        char buf[INET_ADDRSTRLEN > IFNAMSIZ ? INET_ADDRSTRLEN : IFNAMSIZ];
        memcpy(&pktinfo, RSTRING_PTR(data), sizeof(pktinfo));
        if (inet_ntop(AF_INET, &pktinfo.ipi_addr, buf, sizeof(buf)) == NULL)
            rb_str_cat2(ret, " invalid-address");
        else
            rb_str_catf(ret, " %s", buf);
        if (if_indextoname(pktinfo.ipi_ifindex, buf) == NULL)
            rb_str_catf(ret, " ifindex:%d", pktinfo.ipi_ifindex);
        else
            rb_str_catf(ret, " %s", buf);
        if (inet_ntop(AF_INET, &pktinfo.ipi_spec_dst, buf, sizeof(buf)) == NULL)
            rb_str_cat2(ret, " spec_dst:invalid-address");
        else
            rb_str_catf(ret, " spec_dst:%s", buf);
        return 1;
    }
    else {
        return 0;
    }
}
#endif

#if defined(IPPROTO_IPV6) && defined(IPV6_PKTINFO) && defined(HAVE_TYPE_STRUCT_IN6_PKTINFO) /* IPv6 RFC3542 */
static int
anc_inspect_ipv6_pktinfo(int level, int type, VALUE data, VALUE ret)
{
    if (level == IPPROTO_IPV6 && type == IPV6_PKTINFO &&
        RSTRING_LEN(data) == sizeof(struct in6_pktinfo)) {
        struct in6_pktinfo *pktinfo = (struct in6_pktinfo *)RSTRING_PTR(data);
        struct in6_addr addr; 
        unsigned int ifindex;
        char addrbuf[INET6_ADDRSTRLEN], ifbuf[IFNAMSIZ];
        memcpy(&addr, &pktinfo->ipi6_addr, sizeof(addr));
        memcpy(&ifindex, &pktinfo->ipi6_ifindex, sizeof(ifindex));
        if (inet_ntop(AF_INET6, &addr, addrbuf, sizeof(addrbuf)) == NULL)
            rb_str_cat2(ret, " invalid-address");
        else
            rb_str_catf(ret, " %s", addrbuf);
        if (if_indextoname(ifindex, ifbuf) == NULL)
            rb_str_catf(ret, " ifindex:%d", ifindex);
        else
            rb_str_catf(ret, " %s", ifbuf);
        return 1;
    }
    else {
        return 0;
    }
}
#endif

/*
 * call-seq:
 *   ancillarydata.inspect => string
 *
 * returns a string which shows ancillarydata in human-readable form.
 *
 *   p Socket::AncillaryData.new(:INET6, :IPV6, :PKTINFO, "").inspect
 *   #=> "#<Socket::AncillaryData: INET6 IPV6 PKTINFO \"\">"
 */
static VALUE
ancillary_inspect(VALUE self)
{
    VALUE ret;
    int family, level, type;
    VALUE data;
    ID family_id, level_id, type_id;
    VALUE vtype;
    int inspected;

    family = ancillary_family(self);
    level = ancillary_level(self);
    type = ancillary_type(self);
    data = ancillary_data(self);

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

    family_id = intern_family_noprefix(family);
    if (family_id)
        rb_str_catf(ret, " %s", rb_id2name(family_id));
    else
        rb_str_catf(ret, " family:%d", family);

    if (level == SOL_SOCKET) {
        rb_str_cat2(ret, " SOCKET");

        type_id = intern_scm_optname(type);
        if (type_id)
            rb_str_catf(ret, " %s", rb_id2name(type_id));
        else
            rb_str_catf(ret, " cmsg_type:%d", type);
    }
    else if (IS_IP_FAMILY(family)) {
        level_id = intern_iplevel(level);
        if (level_id)
            rb_str_catf(ret, " %s", rb_id2name(level_id));
        else
            rb_str_catf(ret, " cmsg_level:%d", level);

        vtype = ip_cmsg_type_to_sym(level, type);
        if (SYMBOL_P(vtype))
            rb_str_catf(ret, " %s", rb_id2name(SYM2ID(vtype)));
        else
            rb_str_catf(ret, " cmsg_type:%d", type);
    }
    else {
        rb_str_catf(ret, " cmsg_level:%d", level);
        rb_str_catf(ret, " cmsg_type:%d", type);
    }

    inspected = 0;

    if (level == SOL_SOCKET)
        family = AF_UNSPEC;

    switch (family) {
      case AF_UNSPEC:
        switch (level) {
#        if defined(SOL_SOCKET)
          case SOL_SOCKET:
            switch (type) {
#            if defined(SCM_RIGHTS) /* 4.4BSD */
              case SCM_RIGHTS: inspected = anc_inspect_socket_rights(level, type, data, ret); break;
#            endif
#            if defined(SCM_CREDENTIALS) /* GNU/Linux */
              case SCM_CREDENTIALS: inspected = anc_inspect_passcred_credentials(level, type, data, ret); break;
#            endif
#            if defined(INSPECT_SCM_CREDS) /* NetBSD */
              case SCM_CREDS: inspected = anc_inspect_socket_creds(level, type, data, ret); break;
#            endif
            }
            break;
#        endif
        }
        break;
       
      case AF_INET:
#ifdef INET6
      case AF_INET6:
#endif
        switch (level) {
#        if defined(IPPROTO_IP)
          case IPPROTO_IP:
            switch (type) {
#            if defined(IP_RECVDSTADDR) /* 4.4BSD */
              case IP_RECVDSTADDR: inspected = anc_inspect_ip_recvdstaddr(level, type, data, ret); break;
#            endif
#            if defined(IP_PKTINFO) && defined(HAVE_TYPE_STRUCT_IN_PKTINFO) /* GNU/Linux */
              case IP_PKTINFO: inspected = anc_inspect_ip_pktinfo(level, type, data, ret); break;
#            endif
            }
            break;
#        endif

#        if defined(IPPROTO_IPV6)
          case IPPROTO_IPV6:
            switch (type) {
#            if defined(IPV6_PKTINFO) /* RFC 3542 */
              case IPV6_PKTINFO: inspected = anc_inspect_ipv6_pktinfo(level, type, data, ret); break;
#            endif
            }
            break;
#        endif
        }
        break;
    }

    if (!inspected) {
        data = rb_str_dump(data);
        rb_str_catf(ret, " %s", StringValueCStr(data));
    }

    rb_str_cat2(ret, ">");

    return ret;
}

/*
 * call-seq:
 *   ancillarydata.cmsg_is?(level, type) => true or false
 *
 * tests the level and type of _ancillarydata_.
 *
 *   ancdata = Socket::AncillaryData.new(:INET6, :IPV6, :PKTINFO, "")
 *   ancdata.cmsg_is?(Socket::IPPROTO_IPV6, Socket::IPV6_PKTINFO) #=> true
 *   ancdata.cmsg_is?(:IPV6, :PKTINFO)       #=> true
 *   ancdata.cmsg_is?(:IP, :PKTINFO)         #=> false
 *   ancdata.cmsg_is?(:SOCKET, :RIGHTS)      #=> false
 */
static VALUE
ancillary_cmsg_is_p(VALUE self, VALUE vlevel, VALUE vtype)
{
    int family = ancillary_family(self);
    int level = level_arg(family, vlevel);
    int type = cmsg_type_arg(family, level, vtype);

    if (ancillary_level(self) == level &&
        ancillary_type(self) == type)
        return Qtrue;
    else
        return Qfalse;
}

#endif

#if defined(HAVE_SENDMSG)
struct sendmsg_args_struct {
    int fd;
    const struct msghdr *msg;
    int flags;
};

static VALUE
nogvl_sendmsg_func(void *ptr)
{
    struct sendmsg_args_struct *args = ptr;
    return sendmsg(args->fd, args->msg, args->flags);
}

static ssize_t
rb_sendmsg(int fd, const struct msghdr *msg, int flags)
{
    struct sendmsg_args_struct args;
    args.fd = fd;
    args.msg = msg;
    args.flags = flags;
    return rb_thread_blocking_region(nogvl_sendmsg_func, &args, RUBY_UBF_IO, 0);
}

static VALUE
bsock_sendmsg_internal(int argc, VALUE *argv, VALUE sock, int nonblock)
{
    rb_io_t *fptr;
    VALUE data, vflags, dest_sockaddr;
    VALUE *controls_ptr;
    int controls_num;
    struct msghdr mh;
    struct iovec iov;
#if defined(HAVE_ST_MSG_CONTROL)
    volatile VALUE controls_str = 0;
#endif
    int flags;
    ssize_t ss;
    int family;

    rb_secure(4);
    GetOpenFile(sock, fptr);
    family = rb_sock_getfamily(fptr->fd);

    data = vflags = dest_sockaddr = Qnil;
    controls_ptr = NULL;
    controls_num = 0;

    if (argc == 0)
        rb_raise(rb_eArgError, "mesg argument required");
    data = argv[0];
    if (1 < argc) vflags = argv[1];
    if (2 < argc) dest_sockaddr = argv[2];
    if (3 < argc) { controls_ptr = &argv[3]; controls_num = argc - 3; }

    StringValue(data);

    if (controls_num) {
#if defined(HAVE_ST_MSG_CONTROL)
	int i;
	int last_pad = 0;
        controls_str = rb_str_tmp_new(0);
        for (i = 0; i < controls_num; i++) {
            VALUE elt = controls_ptr[i], v;
            VALUE vlevel, vtype;
            int level, type;
            VALUE cdata;
            long oldlen;
            struct cmsghdr *cmh;
            size_t cspace;
            v = rb_check_convert_type(elt, T_ARRAY, "Array", "to_ary");
            if (!NIL_P(v)) {
                elt = v;
                if (RARRAY_LEN(elt) != 3)
                    rb_raise(rb_eArgError, "an element of controls should be 3-elements array");
                vlevel = rb_ary_entry(elt, 0);
                vtype = rb_ary_entry(elt, 1);
                cdata = rb_ary_entry(elt, 2);
            }
            else {
                vlevel = rb_funcall(elt, rb_intern("level"), 0);
                vtype = rb_funcall(elt, rb_intern("type"), 0);
                cdata = rb_funcall(elt, rb_intern("data"), 0);
            }
            level = level_arg(family, vlevel);
            type = cmsg_type_arg(family, level, vtype);
            StringValue(cdata);
            oldlen = RSTRING_LEN(controls_str);
            cspace = CMSG_SPACE(RSTRING_LEN(cdata));
            rb_str_resize(controls_str, oldlen + cspace);
            cmh = (struct cmsghdr *)(RSTRING_PTR(controls_str)+oldlen);
            memset((char *)cmh, 0, cspace);
            cmh->cmsg_level = level;
            cmh->cmsg_type = type;
            cmh->cmsg_len = CMSG_LEN(RSTRING_LEN(cdata));
            MEMCPY(CMSG_DATA(cmh), RSTRING_PTR(cdata), char, RSTRING_LEN(cdata));
	    last_pad = cspace - cmh->cmsg_len;
        }
	if (last_pad) {
	    rb_str_set_len(controls_str, RSTRING_LEN(controls_str)-last_pad);
	}
#else
	rb_raise(rb_eNotImpError, "control message for sendmsg is unimplemented");
#endif
    }

    flags = NIL_P(vflags) ? 0 : NUM2INT(vflags);
#ifdef MSG_DONTWAIT
    if (nonblock)
        flags |= MSG_DONTWAIT;
#endif

    if (!NIL_P(dest_sockaddr))
	SockAddrStringValue(dest_sockaddr);

    rb_io_check_closed(fptr);

  retry:
    memset(&mh, 0, sizeof(mh));
    if (!NIL_P(dest_sockaddr)) {
        mh.msg_name = RSTRING_PTR(dest_sockaddr);
        mh.msg_namelen = RSTRING_LEN(dest_sockaddr);
    }
    mh.msg_iovlen = 1;
    mh.msg_iov = &iov;
    iov.iov_base = RSTRING_PTR(data);
    iov.iov_len = RSTRING_LEN(data);
#if defined(HAVE_ST_MSG_CONTROL)
    if (controls_str) {
        mh.msg_control = RSTRING_PTR(controls_str);
        mh.msg_controllen = RSTRING_LEN(controls_str);
    }
    else {
        mh.msg_control = NULL;
        mh.msg_controllen = 0;
    }
#endif

    rb_io_check_closed(fptr);
    if (nonblock)
        rb_io_set_nonblock(fptr);

    ss = rb_sendmsg(fptr->fd, &mh, flags);

    if (!nonblock && rb_io_wait_writable(fptr->fd)) {
        rb_io_check_closed(fptr);
        goto retry;
    }

    if (ss == -1)
	rb_sys_fail("sendmsg(2)");

    return SSIZET2NUM(ss);
}
#else
static VALUE
bsock_sendmsg_internal(int argc, VALUE *argv, VALUE sock, int nonblock)
{
    rb_notimplement();
}
#endif

/*
 * call-seq:
 *    basicsocket.sendmsg(mesg, flags=0, dest_sockaddr=nil, *controls) => sent_len
 *
 * sendmsg sends a message using sendmsg(2) system call in blocking manner.
 *
 * _mesg_ is a string to send.
 *
 * _flags_ is bitwise OR of MSG_* constants such as Socket::MSG_OOB.
 *
 * _dest_sockaddr_ is a destination socket address for connection-less socket.
 * It should be a sockaddr such as a result of Socket.sockaddr_in.
 * An Addrinfo object can be used too.
 *
 * _controls_ is a list of ancillary data.
 * The element of _controls_ should be Socket::AncillaryData or
 * 3-elements array.
 * The 3-element array should contains cmsg_level, cmsg_type and data.
 *
 * The return value, _sent_len_, is an integer which is the number of bytes sent.
 *
 * sendmsg can be used to implement send_io as follows:
 *
 *   # use Socket::AncillaryData.
 *   ancdata = Socket::AncillaryData.int(:UNIX, :SOCKET, :RIGHTS, io.fileno)       
 *   sock.sendmsg("a", 0, nil, ancdata)
 *
 *   # use 3-element array.
 *   ancdata = [:SOCKET, :RIGHTS, [io.fileno].pack("i!")]
 *   sock.sendmsg("\0", 0, nil, ancdata)
 *
 */
static VALUE
bsock_sendmsg(int argc, VALUE *argv, VALUE sock)
{
    return bsock_sendmsg_internal(argc, argv, sock, 0);
}

/*
 * call-seq:
 *    basicsocket.sendmsg_nonblock(mesg, flags=0, dest_sockaddr=nil, *controls) => sent_len
 *
 * sendmsg_nonblock sends a message using sendmsg(2) system call in non-blocking manner.
 *
 * It is similar to BasicSocket#sendmsg
 * but the non-blocking flag is set before the system call
 * and it doesn't retry the system call.
 *
 */
static VALUE
bsock_sendmsg_nonblock(int argc, VALUE *argv, VALUE sock)
{
    return bsock_sendmsg_internal(argc, argv, sock, 1);
}

#if defined(HAVE_RECVMSG)
struct recvmsg_args_struct {
    int fd;
    struct msghdr *msg;
    int flags;
};

static VALUE
nogvl_recvmsg_func(void *ptr)
{
    struct recvmsg_args_struct *args = ptr;
    return recvmsg(args->fd, args->msg, args->flags);
}

static ssize_t
rb_recvmsg(int fd, struct msghdr *msg, int flags)
{
    struct recvmsg_args_struct args;
    args.fd = fd;
    args.msg = msg;
    args.flags = flags;
    return rb_thread_blocking_region(nogvl_recvmsg_func, &args, RUBY_UBF_IO, 0);
}

static VALUE
bsock_recvmsg_internal(int argc, VALUE *argv, VALUE sock, int nonblock)
{
    rb_io_t *fptr;
    VALUE vmaxdatlen, vmaxctllen, vflags;
    int grow_buffer;
    size_t maxdatlen, maxctllen;
    int flags, orig_flags;
    struct msghdr mh;
    struct iovec iov;
#if defined(HAVE_ST_MSG_CONTROL)
    struct cmsghdr *cmh;
#endif
    struct sockaddr_storage namebuf;
    char datbuf0[4096], *datbuf;
    char ctlbuf0[4096], *ctlbuf;
    VALUE dat_str = Qnil;
    VALUE ctl_str = Qnil;
    VALUE ret;
    ssize_t ss;

    rb_secure(4);

    rb_scan_args(argc, argv, "03", &vmaxdatlen, &vflags, &vmaxctllen);

    maxdatlen = NIL_P(vmaxdatlen) ? sizeof(datbuf0) : NUM2SIZET(vmaxdatlen);
    maxctllen = NIL_P(vmaxctllen) ? sizeof(ctlbuf0) : NUM2SIZET(vmaxctllen);
    flags = NIL_P(vflags) ? 0 : NUM2INT(vflags);
#ifdef MSG_DONTWAIT
    if (nonblock)
        flags |= MSG_DONTWAIT;
#endif
    orig_flags = flags;

    grow_buffer = NIL_P(vmaxdatlen) || NIL_P(vmaxctllen);

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

#if !defined(HAVE_ST_MSG_CONTROL)
    if (grow_buffer) {
	int socktype, optlen = sizeof(socktype);
        if (getsockopt(fptr->fd, SOL_SOCKET, SO_TYPE, (void*)&socktype, &optlen) == -1) {
	    rb_sys_fail("getsockopt(SO_TYPE)");
	}
	if (socktype == SOCK_STREAM)
	    grow_buffer = 0;
    }
#endif

  retry:
    if (maxdatlen <= sizeof(datbuf0))
        datbuf = datbuf0;
    else {
        if (NIL_P(dat_str))
            dat_str = rb_str_tmp_new(maxdatlen);
        else
            rb_str_resize(dat_str, maxdatlen);
        datbuf = RSTRING_PTR(dat_str);
    }

    if (maxctllen <= sizeof(ctlbuf0))
        ctlbuf = ctlbuf0;
    else {
        if (NIL_P(ctl_str))
            ctl_str = rb_str_tmp_new(maxctllen);
        else
            rb_str_resize(ctl_str, maxctllen);
        ctlbuf = RSTRING_PTR(ctl_str);
    }

    memset(&mh, 0, sizeof(mh));

    memset(&namebuf, 0, sizeof(namebuf));
    mh.msg_name = (struct sockaddr *)&namebuf;
    mh.msg_namelen = sizeof(namebuf);

    mh.msg_iov = &iov;
    mh.msg_iovlen = 1;
    iov.iov_base = datbuf;
    iov.iov_len = maxdatlen;

#if defined(HAVE_ST_MSG_CONTROL)
    mh.msg_control = ctlbuf;
    mh.msg_controllen = maxctllen;
#endif

    if (grow_buffer)
        flags |= MSG_PEEK;

    rb_io_check_closed(fptr);
    if (nonblock)
        rb_io_set_nonblock(fptr);

    ss = rb_recvmsg(fptr->fd, &mh, flags);

    if (!nonblock && rb_io_wait_readable(fptr->fd)) {
        rb_io_check_closed(fptr);
        goto retry;
    }

    if (grow_buffer) {
	int grown = 0;
#if defined(HAVE_ST_MSG_CONTROL)
        if (NIL_P(vmaxdatlen) && (mh.msg_flags & MSG_TRUNC)) {
	    maxdatlen *= 2;
	    grown = 1;
	}
        if (NIL_P(vmaxctllen) && (mh.msg_flags & MSG_CTRUNC)) {
	    maxctllen *= 2;
	    grown = 1;
	}
#else
	if (NIL_P(vmaxdatlen) && ss != -1 && ss == iov.iov_len) {
	    maxdatlen *= 2;
	    grown = 1;
	}
#endif
	if (grown) {
	    goto retry;
	}
	else {
            grow_buffer = 0;
            if (flags != orig_flags) {
                flags = orig_flags;
                goto retry;
            }
        }
    }

    if (ss == -1)
	rb_sys_fail("recvmsg(2)");

    if (NIL_P(dat_str))
        dat_str = rb_tainted_str_new(datbuf, ss);
    else {
        rb_str_resize(dat_str, ss);
        OBJ_TAINT(dat_str);
        RBASIC(dat_str)->klass = rb_cString;
    }

    ret = rb_ary_new3(3, dat_str,
                         io_socket_addrinfo(sock, mh.msg_name, mh.msg_namelen),
#if defined(HAVE_ST_MSG_CONTROL)
			 INT2NUM(mh.msg_flags)
#else
			 Qnil
#endif
			 );

#if defined(HAVE_ST_MSG_CONTROL)
    if (mh.msg_controllen) {
        for (cmh = CMSG_FIRSTHDR(&mh); cmh != NULL; cmh = CMSG_NXTHDR(&mh, cmh)) {
            VALUE ctl;
            size_t clen;
            int family;
            if (cmh->cmsg_len == 0) {
                rb_raise(rb_eIOError, "invalid control message (cmsg_len == 0)");
            }
            family = rb_sock_getfamily(fptr->fd);
            clen = (char*)cmh + cmh->cmsg_len - (char*)CMSG_DATA(cmh);
            ctl = ancdata_new(family, cmh->cmsg_level, cmh->cmsg_type, rb_tainted_str_new((char*)CMSG_DATA(cmh), clen));
            rb_ary_push(ret, ctl);
        }
    }
#endif

    return ret;
}
#else
static VALUE
bsock_recvmsg_internal(int argc, VALUE *argv, VALUE sock, int nonblock)
{
    rb_notimplement();
}
#endif

/*
 * call-seq:
 *    basicsocket.recvmsg(maxmesglen=nil, flags=0, maxcontrollen=nil) => [mesg, sender_addrinfo, rflags, *controls]
 *
 * recvmsg receives a message using recvmsg(2) system call in blocking manner.
 *
 * _maxmesglen_ is the maximum length of mesg to receive.
 *
 * _flags_ is bitwise OR of MSG_* constants such as Socket::MSG_PEEK.
 *
 * _maxcontrolslen_ is the maximum length of controls (ancillary data) to receive.
 *
 * The return value is 4-elements array.
 *
 * _mesg_ is a string of the received message.
 *
 * _sender_addrinfo_ is a sender socket address for connection-less socket.
 * It is an Addrinfo object.
 * For connection-oriented socket such as TCP, sender_addrinfo is platform dependent.
 *
 * _rflags_ is a flags on the received message which is bitwise OR of MSG_* constants such as Socket::MSG_TRUNC.
 * It will be nil if the system uses 4.3BSD style old recvmsg system call.
 *
 * _controls_ is ancillary data which is an array of Socket::AncillaryData objects such as:
 *
 *   #<Socket::AncillaryData: AF_UNIX SOCKET RIGHTS 7>
 *
 * _maxmesglen_ and _maxcontrolslen_ can be nil.
 * In that case, the buffer will be grown until the message is not truncated.
 * Internally, MSG_PEEK is used and MSG_TRUNC/MSG_CTRUNC are checked.
 *
 * sendmsg can be used to implement recv_io as follows:
 *
 *   mesg, sender_sockaddr, rflags, *controls = sock.recvmsg
 *   controls.each {|ancdata|
 *     if ancdata.level == Socket::SOL_SOCKET && ancdata.type == Socket::SCM_RIGHTS
 *       return IO.new(ancdata.int)
 *     end
 *   }
 *
 */
static VALUE
bsock_recvmsg(int argc, VALUE *argv, VALUE sock)
{
    return bsock_recvmsg_internal(argc, argv, sock, 0);
}

/*
 * call-seq:
 *    basicsocket.recvmsg_nonblock(maxdatalen=nil, flags=0, maxcontrollen=nil) => [data, sender_addrinfo, rflags, *controls]
 *
 * recvmsg receives a message using recvmsg(2) system call in non-blocking manner.
 *
 * It is similar to BasicSocket#recvmsg
 * but non-blocking flag is set before the system call
 * and it doesn't retry the system call.
 *
 */
static VALUE
bsock_recvmsg_nonblock(int argc, VALUE *argv, VALUE sock)
{
    return bsock_recvmsg_internal(argc, argv, sock, 1);
}

void
Init_ancdata(void)
{
    rb_define_method(rb_cBasicSocket, "sendmsg", bsock_sendmsg, -1);
    rb_define_method(rb_cBasicSocket, "sendmsg_nonblock", bsock_sendmsg_nonblock, -1);
    rb_define_method(rb_cBasicSocket, "recvmsg", bsock_recvmsg, -1);
    rb_define_method(rb_cBasicSocket, "recvmsg_nonblock", bsock_recvmsg_nonblock, -1);

#if defined(HAVE_ST_MSG_CONTROL)
    rb_cAncillaryData = rb_define_class_under(rb_cSocket, "AncillaryData", rb_cObject);
    rb_define_method(rb_cAncillaryData, "initialize", ancillary_initialize, 4);
    rb_define_method(rb_cAncillaryData, "inspect", ancillary_inspect, 0);
    rb_define_method(rb_cAncillaryData, "family", ancillary_family_m, 0);
    rb_define_method(rb_cAncillaryData, "level", ancillary_level_m, 0);
    rb_define_method(rb_cAncillaryData, "type", ancillary_type_m, 0);
    rb_define_method(rb_cAncillaryData, "data", ancillary_data, 0);
    rb_define_method(rb_cAncillaryData, "cmsg_is?", ancillary_cmsg_is_p, 2);
    rb_define_singleton_method(rb_cAncillaryData, "int", ancillary_s_int, 4);
    rb_define_method(rb_cAncillaryData, "int", ancillary_int, 0);
    rb_define_singleton_method(rb_cAncillaryData, "ip_pktinfo", ancillary_s_ip_pktinfo, -1);
    rb_define_method(rb_cAncillaryData, "ip_pktinfo", ancillary_ip_pktinfo, 0);
    rb_define_singleton_method(rb_cAncillaryData, "ipv6_pktinfo", ancillary_s_ipv6_pktinfo, 2);
    rb_define_method(rb_cAncillaryData, "ipv6_pktinfo", ancillary_ipv6_pktinfo, 0);
    rb_define_method(rb_cAncillaryData, "ipv6_pktinfo_addr", ancillary_ipv6_pktinfo_addr, 0);
    rb_define_method(rb_cAncillaryData, "ipv6_pktinfo_ifindex", ancillary_ipv6_pktinfo_ifindex, 0);
#endif
}