summary refs log tree commit diff
path: root/resolv/gethnamaddr.c
blob: 161060ebd6dc53ec033a4e168e33d28254c10f55 (plain) (blame)
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
/*
 * ++Copyright++ 1985, 1988, 1993
 * -
 * Copyright (c) 1985, 1988, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 * 	This product includes software developed by the University of
 * 	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * -
 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies, and that
 * the name of Digital Equipment Corporation not be used in advertising or
 * publicity pertaining to distribution of the document or software without
 * specific, written prior permission.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 * -
 * --Copyright--
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)gethostnamadr.c	8.1 (Berkeley) 6/4/93";
static char rcsid[] = "$Id$";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
#include <resolv.h>
#include <ctype.h>
#include <errno.h>
#include <syslog.h>

#include "res_hconf.h"

#ifndef LOG_AUTH
# define LOG_AUTH 0
#endif

#define MULTI_PTRS_ARE_ALIASES 1	/* XXX - experimental */

#if defined(BSD) && (BSD >= 199103) && defined(AF_INET6)
# include <string.h>
#else
# include "../conf/portability.h"
#endif
#if defined(USE_OPTIONS_H)
# include <../conf/options.h>
#endif

#ifdef SPRINTF_CHAR
# define SPRINTF(x) strlen(sprintf/**/x)
#else
# define SPRINTF(x) sprintf x
#endif

#define	MAXALIASES	35
#define	MAXADDRS	35
#define	MAXADDRBUFSIZE	8192

static const char AskedForGot[] =
			  "gethostby*.getanswer: asked for \"%s\", got \"%s\"";

static char *h_addr_ptrs[MAXADDRS + 1];
static struct hostent *gethostbyname_ipv4 __P((const char *));

static struct hostent host;
static char *host_aliases[MAXALIASES];
static char hostbuf[MAXADDRBUFSIZE];
static u_char host_addr[16];	/* IPv4 or IPv6 */
static FILE *hostf = NULL;
static int stayopen = 0;

static void map_v4v6_address __P((const char *src, char *dst));
static void map_v4v6_hostent __P((struct hostent *hp, char **bp, int *len));

#ifdef RESOLVSORT
static void addrsort __P((char **, int));
#endif

#if PACKETSZ > 1024
#define	MAXPACKET	PACKETSZ
#else
#define	MAXPACKET	1024
#endif

typedef union {
    HEADER hdr;
    u_char buf[MAXPACKET];
} querybuf;

typedef union {
    int32_t al;
    char ac;
} align;

extern int h_errno;

#ifdef DEBUG
static void
dprintf(msg, num)
	char *msg;
	int num;
{
	if (_res.options & RES_DEBUG) {
		int save = errno;

		printf(msg, num);
		errno = save;
	}
}
#else
# define dprintf(msg, num) /*nada*/
#endif

static struct hostent *
getanswer(answer, anslen, qname, qtype)
	const querybuf *answer;
	int anslen;
	const char *qname;
	int qtype;
{
	register const HEADER *hp;
	register const u_char *cp;
	register int n;
	const u_char *eom;
	char *bp, **ap, **hap;
	int type, class, buflen, ancount, qdcount;
	int haveanswer, had_error;
	int toobig = 0;
	char tbuf[MAXDNAME+1];
	const char *tname;
	int (*name_ok) __P((const char *));

	tname = qname;
	host.h_name = NULL;
	eom = answer->buf + anslen;
	switch (qtype) {
	case T_A:
	case T_AAAA:
		name_ok = res_hnok;
		break;
	case T_PTR:
		name_ok = res_dnok;
		break;
	default:
		return (NULL);	/* XXX should be abort(); */
	}
	/*
	 * find first satisfactory answer
	 */
	hp = &answer->hdr;
	ancount = ntohs(hp->ancount);
	qdcount = ntohs(hp->qdcount);
	bp = hostbuf;
	buflen = sizeof hostbuf;
	cp = answer->buf + HFIXEDSZ;
	if (qdcount != 1) {
		h_errno = NO_RECOVERY;
		return (NULL);
	}
	n = dn_expand(answer->buf, eom, cp, bp, buflen);
	if ((n < 0) || !(*name_ok)(bp)) {
		h_errno = NO_RECOVERY;
		return (NULL);
	}
	cp += n + QFIXEDSZ;
	if (qtype == T_A || qtype == T_AAAA) {
		/* res_send() has already verified that the query name is the
		 * same as the one we sent; this just gets the expanded name
		 * (i.e., with the succeeding search-domain tacked on).
		 */
		n = strlen(bp) + 1;		/* for the \0 */
		host.h_name = bp;
		bp += n;
		buflen -= n;
		/* The qname can be abbreviated, but h_name is now absolute. */
		qname = host.h_name;
	}
	ap = host_aliases;
	*ap = NULL;
	host.h_aliases = host_aliases;
	hap = h_addr_ptrs;
	*hap = NULL;
	host.h_addr_list = h_addr_ptrs;
	haveanswer = 0;
	had_error = 0;
	while (ancount-- > 0 && cp < eom && !had_error) {
		n = dn_expand(answer->buf, eom, cp, bp, buflen);
		if ((n < 0) || !(*name_ok)(bp)) {
			had_error++;
			continue;
		}
		cp += n;			/* name */
		type = _getshort(cp);
 		cp += INT16SZ;			/* type */
		class = _getshort(cp);
 		cp += INT16SZ + INT32SZ;	/* class, TTL */
		n = _getshort(cp);
		cp += INT16SZ;			/* len */
		if (class != C_IN) {
			/* XXX - debug? syslog? */
			cp += n;
			continue;		/* XXX - had_error++ ? */
		}
		if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
			if (ap >= &host_aliases[MAXALIASES-1])
				continue;
			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
			if ((n < 0) || !(*name_ok)(tbuf)) {
				had_error++;
				continue;
			}
			cp += n;
			/* Store alias. */
			*ap++ = bp;
			n = strlen(bp) + 1;	/* for the \0 */
			bp += n;
			buflen -= n;
			/* Get canonical name. */
			n = strlen(tbuf) + 1;	/* for the \0 */
			if (n > buflen) {
				had_error++;
				continue;
			}
			strcpy(bp, tbuf);
			host.h_name = bp;
			bp += n;
			buflen -= n;
			continue;
		}
		if (qtype == T_PTR && type == T_CNAME) {
			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
			if ((n < 0) || !res_hnok(tbuf)) {
				had_error++;
				continue;
			}
			cp += n;
			/* Get canonical name. */
			n = strlen(tbuf) + 1;	/* for the \0 */
			if (n > buflen) {
				had_error++;
				continue;
			}
			strcpy(bp, tbuf);
			tname = bp;
			bp += n;
			buflen -= n;
			continue;
		}
		if (type != qtype) {
			syslog(LOG_NOTICE|LOG_AUTH,
	       "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
			       qname, p_class(C_IN), p_type(qtype),
			       p_type(type));
			cp += n;
			continue;		/* XXX - had_error++ ? */
		}
		switch (type) {
		case T_PTR:
			if (strcasecmp(tname, bp) != 0) {
				syslog(LOG_NOTICE|LOG_AUTH,
				       AskedForGot, qname, bp);
				cp += n;
				continue;	/* XXX - had_error++ ? */
			}
			n = dn_expand(answer->buf, eom, cp, bp, buflen);
			if ((n < 0) || !res_hnok(bp)) {
				had_error++;
				break;
			}
#if MULTI_PTRS_ARE_ALIASES
			cp += n;
			if (!haveanswer)
				host.h_name = bp;
			else if (ap < &host_aliases[MAXALIASES-1])
				*ap++ = bp;
			else
				n = -1;
			if (n != -1) {
				n = strlen(bp) + 1;	/* for the \0 */
				bp += n;
				buflen -= n;
			}
			break;
#else
			host.h_name = bp;
			if (_res.options & RES_USE_INET6) {
				n = strlen(bp) + 1;	/* for the \0 */
				bp += n;
				buflen -= n;
				map_v4v6_hostent(&host, &bp, &buflen);
			}
			h_errno = NETDB_SUCCESS;
			return (&host);
#endif
		case T_A:
		case T_AAAA:
			if (strcasecmp(host.h_name, bp) != 0) {
				syslog(LOG_NOTICE|LOG_AUTH,
				       AskedForGot, host.h_name, bp);
				cp += n;
				continue;	/* XXX - had_error++ ? */
			}
			if (haveanswer) {
				if (n != host.h_length) {
					cp += n;
					continue;
				}
			} else {
				register int nn;

				host.h_name = bp;
				nn = strlen(bp) + 1;	/* for the \0 */
				bp += nn;
				buflen -= nn;
			}

			bp += sizeof(align) - ((u_long)bp % sizeof(align));

			if (bp + n >= &hostbuf[sizeof hostbuf]) {
				dprintf("size (%d) too big\n", n);
				had_error++;
				continue;
			}
			if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
				if (!toobig++)
					dprintf("Too many addresses (%d)\n",
						MAXADDRS);
				cp += n;
				continue;
			}
			bcopy(cp, *hap++ = bp, n);
			bp += n;
			cp += n;
			break;
		default:
			abort();
		}
		if (!had_error)
			haveanswer++;
	}
	if (haveanswer) {
		*ap = NULL;
		*hap = NULL;
# if defined(RESOLVSORT)
		/*
		 * Note: we sort even if host can take only one address
		 * in its return structures - should give it the "best"
		 * address in that case, not some random one
		 */
		if (_res.nsort && haveanswer > 1 && qtype == T_A)
			addrsort(h_addr_ptrs, haveanswer);
# endif /*RESOLVSORT*/
		if (!host.h_name) {
			n = strlen(qname) + 1;	/* for the \0 */
			if (n > buflen)
				goto try_again;
			strcpy(bp, qname);
			host.h_name = bp;
			bp += n;
			buflen -= n;
		}
		if (_res.options & RES_USE_INET6)
			map_v4v6_hostent(&host, &bp, &buflen);
		h_errno = NETDB_SUCCESS;
		return (&host);
	}
 try_again:
	h_errno = TRY_AGAIN;
	return (NULL);
}

struct hostent *
gethostbyname(name)
	const char *name;
{
	struct hostent *hp;

	if (_res.options & RES_USE_INET6) {
		hp = gethostbyname2(name, AF_INET6);
		if (hp)
			return (hp);
	}
	return (gethostbyname2(name, AF_INET));
}

struct hostent *
gethostbyname2(name, af)
	const char *name;
	int af;
{
	querybuf buf;
	register const char *cp;
	char *bp;
	int i, n, size, type, len;
	extern struct hostent *_gethtbyname2();

	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}

	switch (af) {
	case AF_INET:
		size = INADDRSZ;
		type = T_A;
		break;
	case AF_INET6:
		size = IN6ADDRSZ;
		type = T_AAAA;
		break;
	default:
		h_errno = NETDB_INTERNAL;
		errno = EAFNOSUPPORT;
		return (NULL);
	}

	host.h_addrtype = af;
	host.h_length = size;

	/*
	 * if there aren't any dots, it could be a user-level alias.
	 * this is also done in res_query() since we are not the only
	 * function that looks up host names.
	 */
	if (!strchr(name, '.') && (cp = __hostalias(name)))
		name = cp;

	/*
	 * disallow names consisting only of digits/dots, unless
	 * they end in a dot.
	 */
	if (isdigit(name[0]))
		for (cp = name;; ++cp) {
			if (!*cp) {
				if (*--cp == '.')
					break;
				/*
				 * All-numeric, no dot at the end.
				 * Fake up a hostent as if we'd actually
				 * done a lookup.
				 */
				if (inet_pton(af, name, host_addr) <= 0) {
					h_errno = HOST_NOT_FOUND;
					return (NULL);
				}
				strncpy(hostbuf, name, MAXDNAME);
				hostbuf[MAXDNAME] = '\0';
				bp = hostbuf + MAXDNAME;
				len = sizeof hostbuf - MAXDNAME;
				host.h_name = hostbuf;
				host.h_aliases = host_aliases;
				host_aliases[0] = NULL;
				h_addr_ptrs[0] = (char *)host_addr;
				h_addr_ptrs[1] = NULL;
				host.h_addr_list = h_addr_ptrs;
				if (_res.options & RES_USE_INET6)
					map_v4v6_hostent(&host, &bp, &len);
				h_errno = NETDB_SUCCESS;
				return (&host);
			}
			if (!isdigit(*cp) && *cp != '.')
				break;
		}

	h_errno = HOST_NOT_FOUND;
	for (i = 0; i < _res_hconf.num_services; ++i) {
		struct hostent * hp;
		char * cp = (char *) name;

		if (_res_hconf.num_trimdomains > 0) {
			size_t name_len = strlen(name);

			cp = malloc(name_len + 1);
			memcpy(cp, name, name_len + 1);
			_res_hconf_trim_domain(cp);
		}

		hp = NULL;
		switch (_res_hconf.service[i]) {
		      case SERVICE_BIND:
			if ((n = res_search(cp, C_IN, type,
					    buf.buf, sizeof(buf))) < 0)
			{
				dprintf("res_search failed (%d)\n", n);
				break;
			}
			hp = getanswer(&buf, n, cp, type);
			break;

		      case SERVICE_HOSTS:
			hp = _gethtbyname2(cp, af);
			break;
#ifdef HAVE_NYS
		      case SERVICE_NIS:
			hp = _getnishost(cp, "hosts.byname");
			break;
#endif
		      default:
			break;
		}
		if (cp != name)
			free(cp);
		if (hp) {
			if ((_res_hconf.flags & HCONF_FLAG_REORDER)
			    && hp->h_addr_list[0] && hp->h_addr_list[1])
				_res_hconf_reorder_addrs(hp);
			_res_hconf_trim_domains(hp);
			return hp;
		}
	}
	if (h_errno == NETDB_SUCCESS)
		h_errno = HOST_NOT_FOUND;
	return NULL;
}

struct hostent *
gethostbyaddr(addr, len, af)
	const char *addr;	/* XXX should have been def'd as u_char! */
	int len, af;
{
	const u_char *uaddr = (const u_char *)addr;
	static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
	static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
	int n, size;
	querybuf buf;
	register struct hostent *hp;
	char qbuf[MAXDNAME+1], *qp;
	register struct hostent *rhp;
	char **haddr;
	u_long old_options;
	char hname2[MAXDNAME+1];
	int i, old_num_trimdomains;
	extern struct hostent *_gethtbyaddr();

	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}
	if (af == AF_INET6 && len == IN6ADDRSZ &&
	    (!bcmp(uaddr, mapped, sizeof mapped) ||
	     !bcmp(uaddr, tunnelled, sizeof tunnelled))) {
		/* Unmap. */
		addr += sizeof mapped;
		uaddr += sizeof mapped;
		af = AF_INET;
		len = INADDRSZ;
	}
	switch (af) {
	case AF_INET:
		size = INADDRSZ;
		break;
	case AF_INET6:
		size = IN6ADDRSZ;
		break;
	default:
		errno = EAFNOSUPPORT;
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}
	if (size != len) {
		errno = EINVAL;
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}

	h_errno = NETDB_SUCCESS;
	for (i = 0; i < _res_hconf.num_services; ++i) {
		hp = NULL;
		switch (_res_hconf.service[i]) {
		case SERVICE_BIND:
			switch (af) {
			case AF_INET:
				(void) sprintf(qbuf,
					       "%u.%u.%u.%u.in-addr.arpa",
					       (uaddr[3] & 0xff),
					       (uaddr[2] & 0xff),
					       (uaddr[1] & 0xff),
					       (uaddr[0] & 0xff));
				break;
			case AF_INET6:
				qp = qbuf;
				for (n = IN6ADDRSZ - 1; n >= 0; n--) {
					qp += SPRINTF((qp, "%x.%x.",
						       uaddr[n] & 0xf,
						       (uaddr[n] >> 4) & 0xf));
				}
				strcpy(qp, "ip6.int");
				break;
			default:
				abort();
			}
			n = res_query(qbuf, C_IN, T_PTR,
				      (u_char *)buf.buf, sizeof buf.buf);
			if (n < 0) {
				dprintf("res_query failed (%d)\n", n);
				break;
			}
			hp = getanswer(&buf, n, qbuf, T_PTR);
			if (!hp)
				break;	/* h_errno was set by getanswer() */
			if (af == AF_INET
			    && (_res_hconf.flags & HCONF_FLAG_SPOOF)) {
				/*
				 * Turn off search as the name should
				 * be absolute, 'localhost' should be
				 * matched by defnames
				 */
				strncpy(hname2, hp->h_name, MAXDNAME);
				hname2[MAXDNAME] = '\0';
				old_options = _res.options;
				/*
				 * Also turn off domain trimming to prevent it
				 * from causing the name comparison to fail.
				 */
				old_num_trimdomains =
					_res_hconf.num_trimdomains;
				_res.options &= ~RES_DNSRCH;
				_res.options |= RES_DEFNAMES;
				rhp = gethostbyname(hname2);
				_res.options = old_options;
				/* There must be an A record and
				   the names must match.  */
				if (!rhp || strcmp(hname2, rhp->h_name)) {
					syslog(LOG_NOTICE|LOG_AUTH,
					       "gethostbyaddr: No A record for"
					       " %s (verifying [%s])",
					       hname2,
					       inet_ntoa(*((struct in_addr *)
							   addr)));
					h_errno = HOST_NOT_FOUND;
					break;
				}
				for (haddr = rhp->h_addr_list; *haddr; haddr++)
					if (!memcmp(*haddr, addr, INADDRSZ))
						break;
				if (!*haddr) {
					syslog(LOG_NOTICE|LOG_AUTH,
					       "gethostbyaddr: A record of %s"
					       " != PTR record [%s]",
					       hname2,
					       inet_ntoa(*((struct in_addr *)
							   addr)));
					h_errno = HOST_NOT_FOUND;
					break;
				}
			}
			hp->h_addrtype = af;
			hp->h_length = len;
			bcopy(addr, host_addr, len);
			h_addr_ptrs[0] = (char *)host_addr;
			h_addr_ptrs[1] = NULL;
			if (af == AF_INET && (_res.options & RES_USE_INET6)) {
				map_v4v6_address((char*)host_addr,
						 (char*)host_addr);
				hp->h_addrtype = AF_INET6;
				hp->h_length = IN6ADDRSZ;
			}
			h_errno = NETDB_SUCCESS;
			break;

		case SERVICE_HOSTS:
			hp = _gethtbyaddr(addr, len, af);
			break;

#ifdef HAVE_NYS
		case SERVICE_NIS:
			if (af == AF_INET) {
				sprintf(qbuf, "%u.%u.%u.%u",
					(unsigned)addr[0] & 0xff,
					(unsigned)addr[1] & 0xff,
					(unsigned)addr[2] & 0xff,
					(unsigned)addr[3] & 0xff);
				hp = _getnishost(qbuf, "hosts.byaddr");
			}
			break;
#endif

		default:
			break;
		}
		if (hp) {
			_res_hconf_trim_domains(hp);
			return hp;
		}
	}
	if (h_errno == NETDB_SUCCESS)
		h_errno = HOST_NOT_FOUND;
	return NULL;
}

void
_sethtent(f)
	int f;
{
	if (!hostf)
		hostf = fopen(_PATH_HOSTS, "r" );
	else
		rewind(hostf);
	stayopen = f;
}

void
_endhtent()
{
	if (hostf && !stayopen) {
		(void) fclose(hostf);
		hostf = NULL;
	}
}

struct hostent *
_gethtent()
{
	char *p;
	register char *cp, **q;
	int af, len;

	if (!hostf && !(hostf = fopen(_PATH_HOSTS, "r" ))) {
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}
 again:
	if (!(p = fgets(hostbuf, sizeof hostbuf, hostf))) {
		h_errno = HOST_NOT_FOUND;
		return (NULL);
	}
	if (*p == '#')
		goto again;
	if (!(cp = strpbrk(p, "#\n")))
		goto again;
	*cp = '\0';
	if (!(cp = strpbrk(p, " \t")))
		goto again;
	*cp++ = '\0';
	if ((_res.options & RES_USE_INET6) &&
	    inet_pton(AF_INET6, p, host_addr) > 0) {
		af = AF_INET6;
		len = IN6ADDRSZ;
	} else if (inet_pton(AF_INET, p, host_addr) > 0) {
		if (_res.options & RES_USE_INET6) {
			map_v4v6_address((char*)host_addr, (char*)host_addr);
			af = AF_INET6;
			len = IN6ADDRSZ;
		} else {
			af = AF_INET;
			len = INADDRSZ;
		}
	} else {
		goto again;
	}
	h_addr_ptrs[0] = (char *)host_addr;
	h_addr_ptrs[1] = NULL;
	host.h_addr_list = h_addr_ptrs;
	host.h_length = len;
	host.h_addrtype = af;
	while (*cp == ' ' || *cp == '\t')
		cp++;
	host.h_name = cp;
	q = host.h_aliases = host_aliases;
	if (cp = strpbrk(cp, " \t"))
		*cp++ = '\0';
	while (cp && *cp) {
		if (*cp == ' ' || *cp == '\t') {
			cp++;
			continue;
		}
		if (q < &host_aliases[MAXALIASES - 1])
			*q++ = cp;
		if (cp = strpbrk(cp, " \t"))
			*cp++ = '\0';
	}
	*q = NULL;
	if (_res.options & RES_USE_INET6) {
		char *bp = hostbuf;
		int buflen = sizeof hostbuf;

		map_v4v6_hostent(&host, &bp, &buflen);
	}
	h_errno = NETDB_SUCCESS;
	return (&host);
}

struct hstorage {
	char	*name;				/* canonical name */
	char **	alp;				/* address list pointer */
	char *	abp;				/* address buffer pointer */
	char *	addr_list[MAXADDRS + 1];	/* address list storage */
	char	addr_buf[MAXADDRBUFSIZE];	/* addresses storage */
};

static void
append_addr (struct hstorage * hs, struct hostent *p)
{
	if (hs->alp < hs->addr_list + MAXADDRS
	    && hs->abp + p->h_length < hs->addr_buf + MAXADDRBUFSIZE)
	{
		hs->alp[0] = hs->abp;
		hs->alp[1] = 0;
		memcpy(hs->abp, p->h_addr_list[0], p->h_length);
		hs->abp += p->h_length;
		++hs->alp;
	}
}

/*
 * Lookup IP address and aliases for host NAME.  If multiaddress mode
 * is enabled, the entire /etc/hosts file is searched and the union of
 * all addresses found for NAME is returned (this may be slow with
 * large /etc/hosts files, but is convenient for smallish sites that
 * don't want to go through the complexity of running named locally).
 * If multiaddress mode is enabled, the address returned in
 * h_addr_list[0] is one that is on the same net as one of the host's
 * local addresses (if such an address exists).  For compatibility
 * with the BIND version of gethostbyname(), the alias field is empty
 * unless the name being looked up is an alias itself.  In the latter
 * case, the name field contains the canonical name and the alias
 * field the name that is being looked up.  A difference from the BIND
 * version is that this is true even if the alias applies only to one
 * of the interfaces on the target host.o
 */
struct hostent *
_gethtbyname(name)
	const char *name;
{
	extern struct hostent *_gethtbyname2();
	struct hostent *hp;

	if (_res.options & RES_USE_INET6) {
		hp = _gethtbyname2(name, AF_INET6);
		if (hp)
			return (hp);
	}
	return (_gethtbyname2(name, AF_INET));
}

struct hostent *
_gethtbyname2(name, af)
	const char *name;
	int af;
{
	register struct hostent *p;
	register char **cp;

	_sethtent(0);

	if (_res_hconf.flags & HCONF_FLAG_MULTI) {
		/*
		 * More statics; not pretty, but it would require
		 * interface changes to make these functions
		 * reentrant.
		 */
		static char *aliases[2] = {0};
		static struct hstorage self = {0}, target = {0};
		static size_t self_name_size = 0; /* Allocated in self.name. */
		static struct hostent ht;
		int found;

		if (aliases[0])
			free (aliases[0]);	/* Malloced in a prev call.  */
		aliases[0] = aliases[1] = 0;

		/* Get current host name in a large enough buffer.  */
		do {
			   errno = 0;

			   if (self.name)
			   {
				   self_name_size += self_name_size;
				   self.name =
					   realloc (self.name, self_name_size);
			   } else {
				   self_name_size = 128; /* Initial guess */
				   self.name = malloc (self_name_size);
			   }

			   if (! self.name)
			   {
				   errno = ENOMEM;
				   return 0;
			   }
		   } while ((gethostname(self.name, self_name_size) == 0
			     && !memchr (self.name, '\0', self_name_size))
			    || errno == ENAMETOOLONG);
		
		if (errno)
			/* gethostname failed, abort.  */
		{
			free (self.name);
			self.name = 0;
		}

		self.alp = self.addr_list;
		self.abp = self.addr_buf;

		if (target.name)
			free (target.name);
		target.name = strdup (name);

		target.alp = target.addr_list;
		target.abp = target.addr_buf;

		_sethtent(0);
		while ((p = _gethtent()) != 0) {
			found = 1;

			if (p->h_addrtype != af)
				continue;
			if (strcasecmp(p->h_name, name) != 0) {
				found = 0;
				for (cp = p->h_aliases; *cp; ++cp)
					if (strcasecmp(*cp, name) == 0) {
						found = 1;
						if (!aliases[0]) {
							aliases[0] =
							  target.name;
							target.name =
							  strdup (p->h_name);
						}
						break;
					}
			}
			if (found) {
				/* they better be all the same type and length! */
				ht.h_addrtype = p->h_addrtype;
				ht.h_length = p->h_length;
				append_addr(&target, p);
				/*
				 * If the current hostentry is for the target host, we don't
				 * check for the local host name.  This nicely optimizes the
				 * case where NAME is a local name since address ordering
				 * doesn't matter in that case.
				 */
				continue;
			}
			found = 1;
			if (strcasecmp(p->h_name, self.name) != 0) {
				found = 0;
				for (cp = p->h_aliases; *cp; ++cp)
					if (strcasecmp(*cp, self.name) == 0) {
						found = 1;
						break;
					}
			}
			if (found) {
				append_addr(&self, p);
			}
		}
		_endhtent();

		if (target.alp == target.addr_list)
			return NULL;		/* found nothing */

		ht.h_aliases   = aliases;
		ht.h_name      = target.name;
		ht.h_addr_list = target.addr_list;
		/*
		 * XXX (davidm) Isn't this subsumed by REORDER???
		 *
		 * Finding the `best' address is necessarily address
		 * specific.  For now, we do IPv4 addresses only.
		 */
		if (af == AF_INET) {
			u_int32_t a1, a2, diff, mindiff = ~0;
			int i, j, bestaddr = 0;

			for (i = 0; self.addr_list[i]; ++i) {
				for (j = 0; target.addr_list[j]; ++j) {
					memcpy(&a1, self.addr_list[i], 4);
					memcpy(&a2, target.addr_list[j], 4);
					a1 = ntohl(a1);
					a2 = ntohl(a2);
					diff = a1 ^ a2;
					if (diff < mindiff) {
						bestaddr = j;
						mindiff = diff;
					}
				}
			}
			if (bestaddr > 0) {
				char * tmp;

				tmp = target.addr_list[0];
				target.addr_list[0] = target.addr_list[bestaddr];
				target.addr_list[bestaddr] = tmp;
			}
		} else if (af == AF_INET6) {
			/* XXX To do!!! */
		}
		ht.h_addr_list = target.addr_list;
		return &ht;
	} else {
		_sethtent(0);
		while (p = _gethtent()) {
			if (p->h_addrtype != af)
				continue;
			if (strcasecmp(p->h_name, name) == 0)
				break;
			for (cp = p->h_aliases; *cp != 0; cp++)
				if (strcasecmp(*cp, name) == 0)
					goto found;
		}
	}
 found:
	_endhtent();
	return (p);
}

struct hostent *
_gethtbyaddr(addr, len, af)
	const char *addr;
	int len, af;
{
	register struct hostent *p;

	_sethtent(0);
	while (p = _gethtent())
		if (p->h_addrtype == af && !bcmp(p->h_addr, addr, len))
			break;
	_endhtent();
	return (p);
}

static void
map_v4v6_address(src, dst)
	const char *src;
	char *dst;
{
	u_char *p = (u_char *)dst;
	char tmp[INADDRSZ];
	int i;

	/* Stash a temporary copy so our caller can update in place. */
	bcopy(src, tmp, INADDRSZ);
	/* Mark this ipv6 addr as a mapped ipv4. */
	for (i = 0; i < 10; i++)
		*p++ = 0x00;
	*p++ = 0xff;
	*p++ = 0xff;
	/* Retrieve the saved copy and we're done. */
	bcopy(tmp, (void*)p, INADDRSZ);
}

static void
map_v4v6_hostent(hp, bpp, lenp)
	struct hostent *hp;
	char **bpp;
	int *lenp;
{
	char **ap;

	if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
		return;
	hp->h_addrtype = AF_INET6;
	hp->h_length = IN6ADDRSZ;
	for (ap = hp->h_addr_list; *ap; ap++) {
		int i = sizeof(align) - ((u_long)*bpp % sizeof(align));

		if (*lenp < (i + IN6ADDRSZ)) {
			/* Out of memory.  Truncate address list here.  XXX */
			*ap = NULL;
			return;
		}
		*bpp += i;
		*lenp -= i;
		map_v4v6_address(*ap, *bpp);
		*ap = *bpp;
		*bpp += IN6ADDRSZ;
		*lenp -= IN6ADDRSZ;
	}
}

#ifdef RESOLVSORT
static void
addrsort(ap, num)
	char **ap;
	int num;
{
	int i, j;
	char **p;
	short aval[MAXADDRS];
	int needsort = 0;

	p = ap;
	for (i = 0; i < num; i++, p++) {
	    for (j = 0 ; (unsigned)j < _res.nsort; j++)
		if (_res.sort_list[j].addr.s_addr ==
		    (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
			break;
	    aval[i] = j;
	    if (needsort == 0 && i > 0 && j < aval[i-1])
		needsort = i;
	}
	if (!needsort)
	    return;

	while (needsort < num) {
	    for (j = needsort - 1; j >= 0; j--) {
		if (aval[j] > aval[j+1]) {
		    char *hp;

		    i = aval[j];
		    aval[j] = aval[j+1];
		    aval[j+1] = i;

		    hp = ap[j];
		    ap[j] = ap[j+1];
		    ap[j+1] = hp;

		} else
		    break;
	    }
	    needsort++;
	}
}
#endif

#if defined(BSD43_BSD43_NFS) || defined(sun)
/* some libc's out there are bound internally to these names (UMIPS) */
void
ht_sethostent(stayopen)
	int stayopen;
{
	_sethtent(stayopen);
}

void
ht_endhostent()
{
	_endhtent();
}

struct hostent *
ht_gethostbyname(name)
	char *name;
{
	return (_gethtbyname(name));
}

struct hostent *
ht_gethostbyaddr(addr, len, af)
	const char *addr;
	int len, af;
{
	return (_gethtbyaddr(addr, len, af));
}

struct hostent *
gethostent()
{
	struct hostent * hp;
	int i;

	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}

	/*
	 * This doesn't look quite right.  Shouldn't we read one
	 * service until it returns 0, then move on to the next
	 * service?  If so, it requires adding some state and
	 * initializing that state in sethostent().
	 * (davidm@azstarnet.com)
	 */
	for (i = 0; i < _res_hconf.num_services; ++i) {
		hp = NULL;
		switch (_res_hconf.service[i]) {
		      case SERVICE_HOSTS:
			hp = _gethtent ();
			break;

#ifdef HAVE_NYS
		      case SERVICE_NIS:
			hp = _getnishost (NULL, "hosts.byname");
			break;
#endif

		      case SERVICE_BIND:
		      default:
			break;
		}
		if (hp) {
			if ((_res_hconf.flags & HCONF_FLAG_REORDER)
			    && hp->h_addr_list[0] && hp->h_addr_list[1])
				_res_hconf_reorder_addrs (hp);
			return hp;
		}
	}
	h_errno = HOST_NOT_FOUND;
	return NULL;
}

void
dns_service()
{
	return;
}

#undef dn_skipname
dn_skipname(comp_dn, eom)
	const u_char *comp_dn, *eom;
{
	return (__dn_skipname(comp_dn, eom));
}
#endif /*old-style libc with yp junk in it*/