xref: /freebsd/lib/libc/net/gethostbydns.c (revision a0409676120c1e558d0ade943019934e0f15118d)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * ++Copyright++ 1985, 1988, 1993
5  * -
6  * Copyright (c) 1985, 1988, 1993
7  *	The Regents of the University of California.  All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. Neither the name of the University nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  * -
33  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
34  *
35  * Permission to use, copy, modify, and distribute this software for any
36  * purpose with or without fee is hereby granted, provided that the above
37  * copyright notice and this permission notice appear in all copies, and that
38  * the name of Digital Equipment Corporation not be used in advertising or
39  * publicity pertaining to distribution of the document or software without
40  * specific, written prior permission.
41  *
42  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
43  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
44  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
45  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
46  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
47  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
48  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
49  * SOFTWARE.
50  * -
51  * --Copyright--
52  */
53 
54 #if defined(LIBC_SCCS) && !defined(lint)
55 static char sccsid[] = "@(#)gethostnamadr.c	8.1 (Berkeley) 6/4/93";
56 static char fromrcsid[] = "From: Id: gethnamaddr.c,v 8.23 1998/04/07 04:59:46 vixie Exp $";
57 #endif /* LIBC_SCCS and not lint */
58 #include <sys/cdefs.h>
59 __FBSDID("$FreeBSD$");
60 
61 #include <sys/param.h>
62 #include <sys/socket.h>
63 #include <netinet/in.h>
64 #include <arpa/inet.h>
65 #include <arpa/nameser.h>
66 
67 #include <stdio.h>
68 #include <stdlib.h>
69 #include <unistd.h>
70 #include <string.h>
71 #include <netdb.h>
72 #include <resolv.h>
73 #include <ctype.h>
74 #include <errno.h>
75 #include <syslog.h>
76 #include <stdarg.h>
77 #include <nsswitch.h>
78 
79 #include "netdb_private.h"
80 #include "res_config.h"
81 
82 #define SPRINTF(x) ((size_t)sprintf x)
83 
84 static const char AskedForGot[] =
85 		"gethostby*.gethostanswer: asked for \"%s\", got \"%s\"";
86 
87 #ifdef RESOLVSORT
88 static void addrsort(char **, int, res_state);
89 #endif
90 
91 #ifdef DEBUG
92 static void dbg_printf(char *, int, res_state) __printflike(1, 0);
93 #endif
94 
95 #define MAXPACKET	(64*1024)
96 
97 typedef union {
98     HEADER hdr;
99     u_char buf[MAXPACKET];
100 } querybuf;
101 
102 typedef union {
103     int32_t al;
104     char ac;
105 } align;
106 
107 int _dns_ttl_;
108 
109 #ifdef DEBUG
110 static void
111 dbg_printf(char *msg, int num, res_state res)
112 {
113 	if (res->options & RES_DEBUG) {
114 		int save = errno;
115 
116 		printf(msg, num);
117 		errno = save;
118 	}
119 }
120 #else
121 # define dbg_printf(msg, num, res) /*nada*/
122 #endif
123 
124 #define BOUNDED_INCR(x) \
125 	do { \
126 		cp += x; \
127 		if (cp > eom) { \
128 			RES_SET_H_ERRNO(statp, NO_RECOVERY); \
129 			return (-1); \
130 		} \
131 	} while (0)
132 
133 #define BOUNDS_CHECK(ptr, count) \
134 	do { \
135 		if ((ptr) + (count) > eom) { \
136 			RES_SET_H_ERRNO(statp, NO_RECOVERY); \
137 			return (-1); \
138 		} \
139 	} while (0)
140 
141 static int
142 gethostanswer(const querybuf *answer, int anslen, const char *qname, int qtype,
143     struct hostent *he, struct hostent_data *hed, res_state statp)
144 {
145 	const HEADER *hp;
146 	const u_char *cp;
147 	int n;
148 	const u_char *eom, *erdata;
149 	char *bp, *ep, **ap, **hap;
150 	int type, class, ancount, qdcount;
151 	int haveanswer, had_error;
152 	int toobig = 0;
153 	char tbuf[MAXDNAME];
154 	const char *tname;
155 	int (*name_ok)(const char *);
156 
157 	tname = qname;
158 	he->h_name = NULL;
159 	eom = answer->buf + anslen;
160 	switch (qtype) {
161 	case T_A:
162 	case T_AAAA:
163 		name_ok = res_hnok;
164 		break;
165 	case T_PTR:
166 		name_ok = res_dnok;
167 		break;
168 	default:
169 		RES_SET_H_ERRNO(statp, NO_RECOVERY);
170 		return (-1);	/* XXX should be abort(); */
171 	}
172 	/*
173 	 * find first satisfactory answer
174 	 */
175 	hp = &answer->hdr;
176 	ancount = ntohs(hp->ancount);
177 	qdcount = ntohs(hp->qdcount);
178 	bp = hed->hostbuf;
179 	ep = hed->hostbuf + sizeof hed->hostbuf;
180 	cp = answer->buf;
181 	BOUNDED_INCR(HFIXEDSZ);
182 	if (qdcount != 1) {
183 		RES_SET_H_ERRNO(statp, NO_RECOVERY);
184 		return (-1);
185 	}
186 	n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
187 	if ((n < 0) || !(*name_ok)(bp)) {
188 		RES_SET_H_ERRNO(statp, NO_RECOVERY);
189 		return (-1);
190 	}
191 	BOUNDED_INCR(n + QFIXEDSZ);
192 	if (qtype == T_A || qtype == T_AAAA) {
193 		/* res_send() has already verified that the query name is the
194 		 * same as the one we sent; this just gets the expanded name
195 		 * (i.e., with the succeeding search-domain tacked on).
196 		 */
197 		n = strlen(bp) + 1;		/* for the \0 */
198 		if (n >= MAXHOSTNAMELEN) {
199 			RES_SET_H_ERRNO(statp, NO_RECOVERY);
200 			return (-1);
201 		}
202 		he->h_name = bp;
203 		bp += n;
204 		/* The qname can be abbreviated, but h_name is now absolute. */
205 		qname = he->h_name;
206 	}
207 	ap = hed->host_aliases;
208 	*ap = NULL;
209 	he->h_aliases = hed->host_aliases;
210 	hap = hed->h_addr_ptrs;
211 	*hap = NULL;
212 	he->h_addr_list = hed->h_addr_ptrs;
213 	haveanswer = 0;
214 	had_error = 0;
215 	_dns_ttl_ = -1;
216 	while (ancount-- > 0 && cp < eom && !had_error) {
217 		n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
218 		if ((n < 0) || !(*name_ok)(bp)) {
219 			had_error++;
220 			continue;
221 		}
222 		cp += n;			/* name */
223 		BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
224 		type = _getshort(cp);
225  		cp += INT16SZ;			/* type */
226 		class = _getshort(cp);
227  		cp += INT16SZ;			/* class */
228 		if (qtype == T_A  && type == T_A)
229 			_dns_ttl_ = _getlong(cp);
230 		cp += INT32SZ;			/* TTL */
231 		n = _getshort(cp);
232 		cp += INT16SZ;			/* len */
233 		BOUNDS_CHECK(cp, n);
234 		erdata = cp + n;
235 		if (class != C_IN) {
236 			/* XXX - debug? syslog? */
237 			cp += n;
238 			continue;		/* XXX - had_error++ ? */
239 		}
240 		if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
241 			if (ap >= &hed->host_aliases[_MAXALIASES-1])
242 				continue;
243 			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
244 			if ((n < 0) || !(*name_ok)(tbuf)) {
245 				had_error++;
246 				continue;
247 			}
248 			cp += n;
249 			if (cp != erdata) {
250 				RES_SET_H_ERRNO(statp, NO_RECOVERY);
251 				return (-1);
252 			}
253 			/* Store alias. */
254 			*ap++ = bp;
255 			n = strlen(bp) + 1;	/* for the \0 */
256 			if (n >= MAXHOSTNAMELEN) {
257 				had_error++;
258 				continue;
259 			}
260 			bp += n;
261 			/* Get canonical name. */
262 			n = strlen(tbuf) + 1;	/* for the \0 */
263 			if (n > ep - bp || n >= MAXHOSTNAMELEN) {
264 				had_error++;
265 				continue;
266 			}
267 			strcpy(bp, tbuf);
268 			he->h_name = bp;
269 			bp += n;
270 			continue;
271 		}
272 		if (qtype == T_PTR && type == T_CNAME) {
273 			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
274 			if (n < 0 || !res_dnok(tbuf)) {
275 				had_error++;
276 				continue;
277 			}
278 			cp += n;
279 			if (cp != erdata) {
280 				RES_SET_H_ERRNO(statp, NO_RECOVERY);
281 				return (-1);
282 			}
283 			/* Get canonical name. */
284 			n = strlen(tbuf) + 1;	/* for the \0 */
285 			if (n > ep - bp || n >= MAXHOSTNAMELEN) {
286 				had_error++;
287 				continue;
288 			}
289 			strcpy(bp, tbuf);
290 			tname = bp;
291 			bp += n;
292 			continue;
293 		}
294 		if (type != qtype) {
295 			if (type != T_SIG && type != ns_t_dname)
296 				syslog(LOG_NOTICE|LOG_AUTH,
297 	"gethostby*.gethostanswer: asked for \"%s %s %s\", got type \"%s\"",
298 				       qname, p_class(C_IN), p_type(qtype),
299 				       p_type(type));
300 			cp += n;
301 			continue;		/* XXX - had_error++ ? */
302 		}
303 		switch (type) {
304 		case T_PTR:
305 			if (strcasecmp(tname, bp) != 0) {
306 				syslog(LOG_NOTICE|LOG_AUTH,
307 				       AskedForGot, qname, bp);
308 				cp += n;
309 				continue;	/* XXX - had_error++ ? */
310 			}
311 			n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
312 			if ((n < 0) || !res_hnok(bp)) {
313 				had_error++;
314 				break;
315 			}
316 #if MULTI_PTRS_ARE_ALIASES
317 			cp += n;
318 			if (cp != erdata) {
319 				RES_SET_H_ERRNO(statp, NO_RECOVERY);
320 				return (-1);
321 			}
322 			if (!haveanswer)
323 				he->h_name = bp;
324 			else if (ap < &hed->host_aliases[_MAXALIASES-1])
325 				*ap++ = bp;
326 			else
327 				n = -1;
328 			if (n != -1) {
329 				n = strlen(bp) + 1;	/* for the \0 */
330 				if (n >= MAXHOSTNAMELEN) {
331 					had_error++;
332 					break;
333 				}
334 				bp += n;
335 			}
336 			break;
337 #else
338 			he->h_name = bp;
339 			if (statp->options & RES_USE_INET6) {
340 				n = strlen(bp) + 1;	/* for the \0 */
341 				if (n >= MAXHOSTNAMELEN) {
342 					had_error++;
343 					break;
344 				}
345 				bp += n;
346 				_map_v4v6_hostent(he, &bp, ep);
347 			}
348 			RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
349 			return (0);
350 #endif
351 		case T_A:
352 		case T_AAAA:
353 			if (strcasecmp(he->h_name, bp) != 0) {
354 				syslog(LOG_NOTICE|LOG_AUTH,
355 				       AskedForGot, he->h_name, bp);
356 				cp += n;
357 				continue;	/* XXX - had_error++ ? */
358 			}
359 			if (n != he->h_length) {
360 				cp += n;
361 				continue;
362 			}
363 			if (!haveanswer) {
364 				int nn;
365 
366 				he->h_name = bp;
367 				nn = strlen(bp) + 1;	/* for the \0 */
368 				bp += nn;
369 			}
370 
371 			bp += sizeof(align) - ((u_long)bp % sizeof(align));
372 
373 			if (bp + n >= ep) {
374 				dbg_printf("size (%d) too big\n", n, statp);
375 				had_error++;
376 				continue;
377 			}
378 			if (hap >= &hed->h_addr_ptrs[_MAXADDRS-1]) {
379 				if (!toobig++)
380 					dbg_printf("Too many addresses (%d)\n",
381 						_MAXADDRS, statp);
382 				cp += n;
383 				continue;
384 			}
385 			memcpy(*hap++ = bp, cp, n);
386 			bp += n;
387 			cp += n;
388 			if (cp != erdata) {
389 				RES_SET_H_ERRNO(statp, NO_RECOVERY);
390 				return (-1);
391 			}
392 			break;
393 		default:
394 			dbg_printf("Impossible condition (type=%d)\n", type,
395 			    statp);
396 			RES_SET_H_ERRNO(statp, NO_RECOVERY);
397 			return (-1);
398 			/* BIND has abort() here, too risky on bad data */
399 		}
400 		if (!had_error)
401 			haveanswer++;
402 	}
403 	if (haveanswer) {
404 		*ap = NULL;
405 		*hap = NULL;
406 # if defined(RESOLVSORT)
407 		/*
408 		 * Note: we sort even if host can take only one address
409 		 * in its return structures - should give it the "best"
410 		 * address in that case, not some random one
411 		 */
412 		if (statp->nsort && haveanswer > 1 && qtype == T_A)
413 			addrsort(hed->h_addr_ptrs, haveanswer, statp);
414 # endif /*RESOLVSORT*/
415 		if (!he->h_name) {
416 			n = strlen(qname) + 1;	/* for the \0 */
417 			if (n > ep - bp || n >= MAXHOSTNAMELEN)
418 				goto no_recovery;
419 			strcpy(bp, qname);
420 			he->h_name = bp;
421 			bp += n;
422 		}
423 		if (statp->options & RES_USE_INET6)
424 			_map_v4v6_hostent(he, &bp, ep);
425 		RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
426 		return (0);
427 	}
428  no_recovery:
429 	RES_SET_H_ERRNO(statp, NO_RECOVERY);
430 	return (-1);
431 }
432 
433 /* XXX: for async DNS resolver in ypserv */
434 struct hostent *
435 __dns_getanswer(const char *answer, int anslen, const char *qname, int qtype)
436 {
437 	struct hostent *he;
438 	struct hostent_data *hed;
439 	int error;
440 	res_state statp;
441 
442 	statp = __res_state();
443 	if ((he = __hostent_init()) == NULL ||
444 	    (hed = __hostent_data_init()) == NULL) {
445 		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
446 		return (NULL);
447 	}
448 	switch (qtype) {
449 	case T_AAAA:
450 		he->h_addrtype = AF_INET6;
451 		he->h_length = NS_IN6ADDRSZ;
452 		break;
453 	case T_A:
454 	default:
455 		he->h_addrtype = AF_INET;
456 		he->h_length = NS_INADDRSZ;
457 		break;
458 	}
459 
460 	error = gethostanswer((const querybuf *)answer, anslen, qname, qtype,
461 	    he, hed, statp);
462 	return (error == 0) ? he : NULL;
463 }
464 
465 int
466 _dns_gethostbyname(void *rval, void *cb_data, va_list ap)
467 {
468 	const char *name;
469 	int af;
470 	char *buffer;
471 	size_t buflen;
472 	int *errnop, *h_errnop;
473 	struct hostent *hptr, he;
474 	struct hostent_data *hed;
475 	querybuf *buf;
476 	int n, type, error;
477 	res_state statp;
478 
479 	name = va_arg(ap, const char *);
480 	af = va_arg(ap, int);
481 	hptr = va_arg(ap, struct hostent *);
482 	buffer = va_arg(ap, char *);
483 	buflen = va_arg(ap, size_t);
484 	errnop = va_arg(ap, int *);
485 	h_errnop = va_arg(ap, int *);
486 
487 	*((struct hostent **)rval) = NULL;
488 
489 	statp = __res_state();
490 	if ((hed = __hostent_data_init()) == NULL) {
491 		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
492 		*h_errnop = statp->res_h_errno;
493 		return (NS_NOTFOUND);
494 	}
495 
496 	he.h_addrtype = af;
497 	switch (af) {
498 	case AF_INET:
499 		he.h_length = NS_INADDRSZ;
500 		type = T_A;
501 		break;
502 	case AF_INET6:
503 		he.h_length = NS_IN6ADDRSZ;
504 		type = T_AAAA;
505 		break;
506 	default:
507 		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
508 		*h_errnop = statp->res_h_errno;
509 		errno = EAFNOSUPPORT;
510 		return (NS_UNAVAIL);
511 	}
512 
513 	if ((buf = malloc(sizeof(*buf))) == NULL) {
514 		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
515 		*h_errnop = statp->res_h_errno;
516 		return (NS_NOTFOUND);
517 	}
518 	n = res_nsearch(statp, name, C_IN, type, buf->buf, sizeof(buf->buf));
519 	if (n < 0) {
520 		free(buf);
521 		dbg_printf("res_nsearch failed (%d)\n", n, statp);
522 		*h_errnop = statp->res_h_errno;
523 		return (NS_NOTFOUND);
524 	} else if (n > sizeof(buf->buf)) {
525 		free(buf);
526 		dbg_printf("static buffer is too small (%d)\n", n, statp);
527 		*h_errnop = statp->res_h_errno;
528 		return (NS_UNAVAIL);
529 	}
530 	error = gethostanswer(buf, n, name, type, &he, hed, statp);
531 	free(buf);
532 	if (error != 0) {
533 		*h_errnop = statp->res_h_errno;
534 		switch (statp->res_h_errno) {
535 		case HOST_NOT_FOUND:
536 			return (NS_NOTFOUND);
537 		case TRY_AGAIN:
538 			return (NS_TRYAGAIN);
539 		default:
540 			return (NS_UNAVAIL);
541 		}
542 		/*NOTREACHED*/
543 	}
544 	if (__copy_hostent(&he, hptr, buffer, buflen) != 0) {
545 		*errnop = errno;
546 		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
547 		*h_errnop = statp->res_h_errno;
548 		return (NS_RETURN);
549 	}
550 	RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
551 	*((struct hostent **)rval) = hptr;
552 	return (NS_SUCCESS);
553 }
554 
555 int
556 _dns_gethostbyaddr(void *rval, void *cb_data, va_list ap)
557 {
558 	const void *addr;
559 	socklen_t len;
560 	int af;
561 	char *buffer;
562 	size_t buflen;
563 	int *errnop, *h_errnop;
564 	const u_char *uaddr;
565 	struct hostent *hptr, he;
566 	struct hostent_data *hed;
567 	int n;
568 	querybuf *buf;
569 	char qbuf[MAXDNAME+1], *qp;
570 	res_state statp;
571 #ifdef SUNSECURITY
572 	struct hostdata rhd;
573 	struct hostent *rhe;
574 	char **haddr;
575 	u_long old_options;
576 	char hname2[MAXDNAME+1], numaddr[46];
577 	int ret_h_error;
578 #endif /*SUNSECURITY*/
579 
580 	addr = va_arg(ap, const void *);
581 	len = va_arg(ap, socklen_t);
582 	af = va_arg(ap, int);
583 	hptr = va_arg(ap, struct hostent *);
584 	buffer = va_arg(ap, char *);
585 	buflen = va_arg(ap, size_t);
586 	errnop = va_arg(ap, int *);
587 	h_errnop = va_arg(ap, int *);
588 	uaddr = (const u_char *)addr;
589 
590 	*((struct hostent **)rval) = NULL;
591 
592 	statp = __res_state();
593 	if ((hed = __hostent_data_init()) == NULL) {
594 		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
595 		*h_errnop = statp->res_h_errno;
596 		return (NS_NOTFOUND);
597 	}
598 
599 	switch (af) {
600 	case AF_INET:
601 		(void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
602 			       (uaddr[3] & 0xff),
603 			       (uaddr[2] & 0xff),
604 			       (uaddr[1] & 0xff),
605 			       (uaddr[0] & 0xff));
606 		break;
607 	case AF_INET6:
608 		qp = qbuf;
609 		for (n = NS_IN6ADDRSZ - 1; n >= 0; n--) {
610 			qp += SPRINTF((qp, "%x.%x.",
611 				       uaddr[n] & 0xf,
612 				       (uaddr[n] >> 4) & 0xf));
613 		}
614 		strlcat(qbuf, "ip6.arpa", sizeof(qbuf));
615 		break;
616 	default:
617 		abort();
618 	}
619 	if ((buf = malloc(sizeof(*buf))) == NULL) {
620 		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
621 		*h_errnop = statp->res_h_errno;
622 		return NS_NOTFOUND;
623 	}
624 	n = res_nquery(statp, qbuf, C_IN, T_PTR, (u_char *)buf->buf,
625 	    sizeof buf->buf);
626 	if (n < 0) {
627 		free(buf);
628 		dbg_printf("res_nquery failed (%d)\n", n, statp);
629 		*h_errnop = statp->res_h_errno;
630 		return (NS_UNAVAIL);
631 	}
632 	if (n > sizeof buf->buf) {
633 		free(buf);
634 		dbg_printf("static buffer is too small (%d)\n", n, statp);
635 		*h_errnop = statp->res_h_errno;
636 		return (NS_UNAVAIL);
637 	}
638 	if (gethostanswer(buf, n, qbuf, T_PTR, &he, hed, statp) != 0) {
639 		free(buf);
640 		*h_errnop = statp->res_h_errno;
641 		switch (statp->res_h_errno) {
642 		case HOST_NOT_FOUND:
643 			return (NS_NOTFOUND);
644 		case TRY_AGAIN:
645 			return (NS_TRYAGAIN);
646 		default:
647 			return (NS_UNAVAIL);
648 		}
649 		/*NOTREACHED*/
650 	}
651 	free(buf);
652 #ifdef SUNSECURITY
653 	if (af == AF_INET) {
654 	    /*
655 	     * turn off search as the name should be absolute,
656 	     * 'localhost' should be matched by defnames
657 	     */
658 	    strncpy(hname2, he.h_name, MAXDNAME);
659 	    hname2[MAXDNAME] = '\0';
660 	    old_options = statp->options;
661 	    statp->options &= ~RES_DNSRCH;
662 	    statp->options |= RES_DEFNAMES;
663 	    memset(&rhd, 0, sizeof rhd);
664 	    rhe = gethostbyname_r(hname2, &rhd.host, &rhd.data,
665 	        sizeof(rhd.data), &ret_h_error);
666 	    if (rhe == NULL) {
667 		if (inet_ntop(af, addr, numaddr, sizeof(numaddr)) == NULL)
668 		    strlcpy(numaddr, "UNKNOWN", sizeof(numaddr));
669 		syslog(LOG_NOTICE|LOG_AUTH,
670 		       "gethostbyaddr: No A record for %s (verifying [%s])",
671 		       hname2, numaddr);
672 		statp->options = old_options;
673 		RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
674 		*h_errnop = statp->res_h_errno;
675 		return (NS_NOTFOUND);
676 	    }
677 	    statp->options = old_options;
678 	    for (haddr = rhe->h_addr_list; *haddr; haddr++)
679 		if (!memcmp(*haddr, addr, NS_INADDRSZ))
680 			break;
681 	    if (!*haddr) {
682 		if (inet_ntop(af, addr, numaddr, sizeof(numaddr)) == NULL)
683 		    strlcpy(numaddr, "UNKNOWN", sizeof(numaddr));
684 		syslog(LOG_NOTICE|LOG_AUTH,
685 		       "gethostbyaddr: A record of %s != PTR record [%s]",
686 		       hname2, numaddr);
687 		RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
688 		*h_errnop = statp->res_h_errno;
689 		return (NS_NOTFOUND);
690 	    }
691 	}
692 #endif /*SUNSECURITY*/
693 	he.h_addrtype = af;
694 	he.h_length = len;
695 	memcpy(hed->host_addr, uaddr, len);
696 	hed->h_addr_ptrs[0] = (char *)hed->host_addr;
697 	hed->h_addr_ptrs[1] = NULL;
698 	if (af == AF_INET && (statp->options & RES_USE_INET6)) {
699 		_map_v4v6_address((char*)hed->host_addr, (char*)hed->host_addr);
700 		he.h_addrtype = AF_INET6;
701 		he.h_length = NS_IN6ADDRSZ;
702 	}
703 	if (__copy_hostent(&he, hptr, buffer, buflen) != 0) {
704 		*errnop = errno;
705 		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
706 		*h_errnop = statp->res_h_errno;
707 		return (NS_RETURN);
708 	}
709 	RES_SET_H_ERRNO(statp, NETDB_SUCCESS);
710 	*((struct hostent **)rval) = hptr;
711 	return (NS_SUCCESS);
712 }
713 
714 #ifdef RESOLVSORT
715 static void
716 addrsort(char **ap, int num, res_state res)
717 {
718 	int i, j;
719 	char **p;
720 	short aval[_MAXADDRS];
721 	int needsort = 0;
722 
723 	p = ap;
724 	for (i = 0; i < num; i++, p++) {
725 	    for (j = 0 ; (unsigned)j < res->nsort; j++)
726 		if (res->sort_list[j].addr.s_addr ==
727 		    (((struct in_addr *)(*p))->s_addr & res->sort_list[j].mask))
728 			break;
729 	    aval[i] = j;
730 	    if (needsort == 0 && i > 0 && j < aval[i-1])
731 		needsort = i;
732 	}
733 	if (!needsort)
734 	    return;
735 
736 	while (needsort < num) {
737 	    for (j = needsort - 1; j >= 0; j--) {
738 		if (aval[j] > aval[j+1]) {
739 		    char *hp;
740 
741 		    i = aval[j];
742 		    aval[j] = aval[j+1];
743 		    aval[j+1] = i;
744 
745 		    hp = ap[j];
746 		    ap[j] = ap[j+1];
747 		    ap[j+1] = hp;
748 
749 		} else
750 		    break;
751 	    }
752 	    needsort++;
753 	}
754 }
755 #endif
756 
757 void
758 _sethostdnsent(int stayopen)
759 {
760 	res_state statp;
761 
762 	statp = __res_state();
763 	if ((statp->options & RES_INIT) == 0 && res_ninit(statp) == -1)
764 		return;
765 	if (stayopen)
766 		statp->options |= RES_STAYOPEN | RES_USEVC;
767 }
768 
769 void
770 _endhostdnsent(void)
771 {
772 	res_state statp;
773 
774 	statp = __res_state();
775 	statp->options &= ~(RES_STAYOPEN | RES_USEVC);
776 	res_nclose(statp);
777 }
778