xref: /freebsd/lib/libc/net/gethostbydns.c (revision ee2ea5ceafed78a5bd9810beb9e3ca927180c226)
1 /*
2  * ++Copyright++ 1985, 1988, 1993
3  * -
4  * Copyright (c) 1985, 1988, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. All advertising materials mentioning features or use of this software
16  *    must display the following acknowledgement:
17  *	This product includes software developed by the University of
18  *	California, Berkeley and its contributors.
19  * 4. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  * -
35  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
36  *
37  * Permission to use, copy, modify, and distribute this software for any
38  * purpose with or without fee is hereby granted, provided that the above
39  * copyright notice and this permission notice appear in all copies, and that
40  * the name of Digital Equipment Corporation not be used in advertising or
41  * publicity pertaining to distribution of the document or software without
42  * specific, written prior permission.
43  *
44  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
45  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
46  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
47  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
48  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
49  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
50  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
51  * SOFTWARE.
52  * -
53  * --Copyright--
54  */
55 
56 #if defined(LIBC_SCCS) && !defined(lint)
57 static char sccsid[] = "@(#)gethostnamadr.c	8.1 (Berkeley) 6/4/93";
58 static char fromrcsid[] = "From: Id: gethnamaddr.c,v 8.23 1998/04/07 04:59:46 vixie Exp $";
59 #endif /* LIBC_SCCS and not lint */
60 #include <sys/cdefs.h>
61 __FBSDID("$FreeBSD$");
62 
63 #include <sys/types.h>
64 #include <sys/param.h>
65 #include <sys/socket.h>
66 #include <netinet/in.h>
67 #include <arpa/inet.h>
68 #include <arpa/nameser.h>
69 
70 #include <stdio.h>
71 #include <unistd.h>
72 #include <string.h>
73 #include <netdb.h>
74 #include <resolv.h>
75 #include <ctype.h>
76 #include <errno.h>
77 #include <syslog.h>
78 #include <stdarg.h>
79 #include <nsswitch.h>
80 
81 #include "res_config.h"
82 
83 #define SPRINTF(x) ((size_t)sprintf x)
84 
85 #define	MAXALIASES	35
86 #define	MAXADDRS	35
87 
88 static const char AskedForGot[] =
89 		"gethostby*.gethostanswer: asked for \"%s\", got \"%s\"";
90 
91 static char *h_addr_ptrs[MAXADDRS + 1];
92 
93 static struct hostent host;
94 static char *host_aliases[MAXALIASES];
95 static char hostbuf[8*1024];
96 static u_char host_addr[16];	/* IPv4 or IPv6 */
97 
98 #ifdef RESOLVSORT
99 static void addrsort(char **, int);
100 #endif
101 
102 #ifdef DEBUG
103 static void dprintf(char *, int) __printflike(1, 0);
104 #endif
105 
106 #if PACKETSZ > 1024
107 #define	MAXPACKET	PACKETSZ
108 #else
109 #define	MAXPACKET	1024
110 #endif
111 
112 typedef union {
113     HEADER hdr;
114     u_char buf[MAXPACKET];
115 } querybuf;
116 
117 typedef union {
118     int32_t al;
119     char ac;
120 } align;
121 
122 extern int h_errno;
123 int _dns_ttl_;
124 
125 #ifdef DEBUG
126 static void
127 dprintf(msg, num)
128 	char *msg;
129 	int num;
130 {
131 	if (_res.options & RES_DEBUG) {
132 		int save = errno;
133 
134 		printf(msg, num);
135 		errno = save;
136 	}
137 }
138 #else
139 # define dprintf(msg, num) /*nada*/
140 #endif
141 
142 #define BOUNDED_INCR(x) \
143 	do { \
144 		cp += x; \
145 		if (cp > eom) { \
146 			h_errno = NO_RECOVERY; \
147 			return (NULL); \
148 		} \
149 	} while (0)
150 
151 #define BOUNDS_CHECK(ptr, count) \
152 	do { \
153 		if ((ptr) + (count) > eom) { \
154 			h_errno = NO_RECOVERY; \
155 			return (NULL); \
156 		} \
157 	} while (0)
158 
159 static struct hostent *
160 gethostanswer(answer, anslen, qname, qtype)
161 	const querybuf *answer;
162 	int anslen;
163 	const char *qname;
164 	int qtype;
165 {
166 	const HEADER *hp;
167 	const u_char *cp;
168 	int n;
169 	const u_char *eom, *erdata;
170 	char *bp, **ap, **hap;
171 	int type, class, buflen, ancount, qdcount;
172 	int haveanswer, had_error;
173 	int toobig = 0;
174 	char tbuf[MAXDNAME];
175 	const char *tname;
176 	int (*name_ok)(const char *);
177 
178 	tname = qname;
179 	host.h_name = NULL;
180 	eom = answer->buf + anslen;
181 	switch (qtype) {
182 	case T_A:
183 	case T_AAAA:
184 		name_ok = res_hnok;
185 		break;
186 	case T_PTR:
187 		name_ok = res_dnok;
188 		break;
189 	default:
190 		h_errno = NO_RECOVERY;
191 		return (NULL);	/* XXX should be abort(); */
192 	}
193 	/*
194 	 * find first satisfactory answer
195 	 */
196 	hp = &answer->hdr;
197 	ancount = ntohs(hp->ancount);
198 	qdcount = ntohs(hp->qdcount);
199 	bp = hostbuf;
200 	buflen = sizeof hostbuf;
201 	cp = answer->buf;
202 	BOUNDED_INCR(HFIXEDSZ);
203 	if (qdcount != 1) {
204 		h_errno = NO_RECOVERY;
205 		return (NULL);
206 	}
207 	n = dn_expand(answer->buf, eom, cp, bp, buflen);
208 	if ((n < 0) || !(*name_ok)(bp)) {
209 		h_errno = NO_RECOVERY;
210 		return (NULL);
211 	}
212 	BOUNDED_INCR(n + QFIXEDSZ);
213 	if (qtype == T_A || qtype == T_AAAA) {
214 		/* res_send() has already verified that the query name is the
215 		 * same as the one we sent; this just gets the expanded name
216 		 * (i.e., with the succeeding search-domain tacked on).
217 		 */
218 		n = strlen(bp) + 1;		/* for the \0 */
219 		if (n >= MAXHOSTNAMELEN) {
220 			h_errno = NO_RECOVERY;
221 			return (NULL);
222 		}
223 		host.h_name = bp;
224 		bp += n;
225 		buflen -= n;
226 		/* The qname can be abbreviated, but h_name is now absolute. */
227 		qname = host.h_name;
228 	}
229 	ap = host_aliases;
230 	*ap = NULL;
231 	host.h_aliases = host_aliases;
232 	hap = h_addr_ptrs;
233 	*hap = NULL;
234 	host.h_addr_list = h_addr_ptrs;
235 	haveanswer = 0;
236 	had_error = 0;
237 	_dns_ttl_ = -1;
238 	while (ancount-- > 0 && cp < eom && !had_error) {
239 		n = dn_expand(answer->buf, eom, cp, bp, buflen);
240 		if ((n < 0) || !(*name_ok)(bp)) {
241 			had_error++;
242 			continue;
243 		}
244 		cp += n;			/* name */
245 		BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
246 		type = _getshort(cp);
247  		cp += INT16SZ;			/* type */
248 		class = _getshort(cp);
249  		cp += INT16SZ;			/* class */
250 		if (qtype == T_A  && type == T_A)
251 			_dns_ttl_ = _getlong(cp);
252 		cp += INT32SZ;			/* TTL */
253 		n = _getshort(cp);
254 		cp += INT16SZ;			/* len */
255 		BOUNDS_CHECK(cp, n);
256 		erdata = cp + n;
257 		if (class != C_IN) {
258 			/* XXX - debug? syslog? */
259 			cp += n;
260 			continue;		/* XXX - had_error++ ? */
261 		}
262 		if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
263 			if (ap >= &host_aliases[MAXALIASES-1])
264 				continue;
265 			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
266 			if ((n < 0) || !(*name_ok)(tbuf)) {
267 				had_error++;
268 				continue;
269 			}
270 			cp += n;
271 			if (cp != erdata) {
272 				h_errno = NO_RECOVERY;
273 				return (NULL);
274 			}
275 			/* Store alias. */
276 			*ap++ = bp;
277 			n = strlen(bp) + 1;	/* for the \0 */
278 			if (n >= MAXHOSTNAMELEN) {
279 				had_error++;
280 				continue;
281 			}
282 			bp += n;
283 			buflen -= n;
284 			/* Get canonical name. */
285 			n = strlen(tbuf) + 1;	/* for the \0 */
286 			if (n > buflen || n >= MAXHOSTNAMELEN) {
287 				had_error++;
288 				continue;
289 			}
290 			strcpy(bp, tbuf);
291 			host.h_name = bp;
292 			bp += n;
293 			buflen -= n;
294 			continue;
295 		}
296 		if (qtype == T_PTR && type == T_CNAME) {
297 			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
298 			if (n < 0 || !res_dnok(tbuf)) {
299 				had_error++;
300 				continue;
301 			}
302 			cp += n;
303 			if (cp != erdata) {
304 				h_errno = NO_RECOVERY;
305 				return (NULL);
306 			}
307 			/* Get canonical name. */
308 			n = strlen(tbuf) + 1;	/* for the \0 */
309 			if (n > buflen || n >= MAXHOSTNAMELEN) {
310 				had_error++;
311 				continue;
312 			}
313 			strcpy(bp, tbuf);
314 			tname = bp;
315 			bp += n;
316 			buflen -= n;
317 			continue;
318 		}
319 		if (type != qtype) {
320 			if (type != T_SIG)
321 				syslog(LOG_NOTICE|LOG_AUTH,
322 	"gethostby*.gethostanswer: asked for \"%s %s %s\", got type \"%s\"",
323 				       qname, p_class(C_IN), p_type(qtype),
324 				       p_type(type));
325 			cp += n;
326 			continue;		/* XXX - had_error++ ? */
327 		}
328 		switch (type) {
329 		case T_PTR:
330 			if (strcasecmp(tname, bp) != 0) {
331 				syslog(LOG_NOTICE|LOG_AUTH,
332 				       AskedForGot, qname, bp);
333 				cp += n;
334 				continue;	/* XXX - had_error++ ? */
335 			}
336 			n = dn_expand(answer->buf, eom, cp, bp, buflen);
337 			if ((n < 0) || !res_hnok(bp)) {
338 				had_error++;
339 				break;
340 			}
341 #if MULTI_PTRS_ARE_ALIASES
342 			cp += n;
343 			if (cp != erdata) {
344 				h_errno = NO_RECOVERY;
345 				return (NULL);
346 			}
347 			if (!haveanswer)
348 				host.h_name = bp;
349 			else if (ap < &host_aliases[MAXALIASES-1])
350 				*ap++ = bp;
351 			else
352 				n = -1;
353 			if (n != -1) {
354 				n = strlen(bp) + 1;	/* for the \0 */
355 				if (n >= MAXHOSTNAMELEN) {
356 					had_error++;
357 					break;
358 				}
359 				bp += n;
360 				buflen -= n;
361 			}
362 			break;
363 #else
364 			host.h_name = bp;
365 			if (_res.options & RES_USE_INET6) {
366 				n = strlen(bp) + 1;	/* for the \0 */
367 				if (n >= MAXHOSTNAMELEN) {
368 					had_error++;
369 					break;
370 				}
371 				bp += n;
372 				buflen -= n;
373 				_map_v4v6_hostent(&host, &bp, &buflen);
374 			}
375 			h_errno = NETDB_SUCCESS;
376 			return (&host);
377 #endif
378 		case T_A:
379 		case T_AAAA:
380 			if (strcasecmp(host.h_name, bp) != 0) {
381 				syslog(LOG_NOTICE|LOG_AUTH,
382 				       AskedForGot, host.h_name, bp);
383 				cp += n;
384 				continue;	/* XXX - had_error++ ? */
385 			}
386 			if (n != host.h_length) {
387 				cp += n;
388 				continue;
389 			}
390 			if (!haveanswer) {
391 				int nn;
392 
393 				host.h_name = bp;
394 				nn = strlen(bp) + 1;	/* for the \0 */
395 				bp += nn;
396 				buflen -= nn;
397 			}
398 
399 			bp += sizeof(align) - ((u_long)bp % sizeof(align));
400 
401 			if (bp + n >= &hostbuf[sizeof hostbuf]) {
402 				dprintf("size (%d) too big\n", n);
403 				had_error++;
404 				continue;
405 			}
406 			if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
407 				if (!toobig++)
408 					dprintf("Too many addresses (%d)\n",
409 						MAXADDRS);
410 				cp += n;
411 				continue;
412 			}
413 			bcopy(cp, *hap++ = bp, n);
414 			bp += n;
415 			buflen -= n;
416 			cp += n;
417 			if (cp != erdata) {
418 				h_errno = NO_RECOVERY;
419 				return (NULL);
420 			}
421 			break;
422 		default:
423 			dprintf("Impossible condition (type=%d)\n", type);
424 			h_errno = NO_RECOVERY;
425 			return (NULL);
426 			/* BIND has abort() here, too risky on bad data */
427 		}
428 		if (!had_error)
429 			haveanswer++;
430 	}
431 	if (haveanswer) {
432 		*ap = NULL;
433 		*hap = NULL;
434 # if defined(RESOLVSORT)
435 		/*
436 		 * Note: we sort even if host can take only one address
437 		 * in its return structures - should give it the "best"
438 		 * address in that case, not some random one
439 		 */
440 		if (_res.nsort && haveanswer > 1 && qtype == T_A)
441 			addrsort(h_addr_ptrs, haveanswer);
442 # endif /*RESOLVSORT*/
443 		if (!host.h_name) {
444 			n = strlen(qname) + 1;	/* for the \0 */
445 			if (n > buflen || n >= MAXHOSTNAMELEN)
446 				goto no_recovery;
447 			strcpy(bp, qname);
448 			host.h_name = bp;
449 			bp += n;
450 			buflen -= n;
451 		}
452 		if (_res.options & RES_USE_INET6)
453 			_map_v4v6_hostent(&host, &bp, &buflen);
454 		h_errno = NETDB_SUCCESS;
455 		return (&host);
456 	}
457  no_recovery:
458 	h_errno = NO_RECOVERY;
459 	return (NULL);
460 }
461 
462 struct hostent *
463 __dns_getanswer(answer, anslen, qname, qtype)
464 	const char *answer;
465 	int anslen;
466 	const char *qname;
467 	int qtype;
468 {
469 	switch(qtype) {
470 	case T_AAAA:
471 		host.h_addrtype = AF_INET6;
472 		host.h_length = IN6ADDRSZ;
473 		break;
474 	case T_A:
475 	default:
476 		host.h_addrtype = AF_INET;
477 		host.h_length = INADDRSZ;
478 		break;
479 	}
480 
481 	return(gethostanswer((const querybuf *)answer, anslen, qname, qtype));
482 }
483 
484 int
485 _dns_gethostbyname(void *rval, void *cb_data, va_list ap)
486 {
487 	const char *name;
488 	int af;
489 	querybuf buf;
490 	const char *cp;
491 	char *bp;
492 	int n, size, type, len;
493 
494 	name = va_arg(ap, const char *);
495 	af = va_arg(ap, int);
496 	*(struct hostent **)rval = NULL;
497 
498 	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
499 		h_errno = NETDB_INTERNAL;
500 		return NS_UNAVAIL;
501 	}
502 
503 	switch (af) {
504 	case AF_INET:
505 		size = INADDRSZ;
506 		type = T_A;
507 		break;
508 	case AF_INET6:
509 		size = IN6ADDRSZ;
510 		type = T_AAAA;
511 		break;
512 	default:
513 		h_errno = NETDB_INTERNAL;
514 		errno = EAFNOSUPPORT;
515 		return NS_UNAVAIL;
516 	}
517 
518 	host.h_addrtype = af;
519 	host.h_length = size;
520 
521 	/*
522 	 * if there aren't any dots, it could be a user-level alias.
523 	 * this is also done in res_query() since we are not the only
524 	 * function that looks up host names.
525 	 */
526 	if (!strchr(name, '.') && (cp = __hostalias(name)))
527 		name = cp;
528 
529 	/*
530 	 * disallow names consisting only of digits/dots, unless
531 	 * they end in a dot.
532 	 */
533 	if (isdigit((unsigned char)name[0]))
534 		for (cp = name;; ++cp) {
535 			if (!*cp) {
536 				if (*--cp == '.')
537 					break;
538 				/*
539 				 * All-numeric, no dot at the end.
540 				 * Fake up a hostent as if we'd actually
541 				 * done a lookup.
542 				 */
543 				if (inet_pton(af, name, host_addr) <= 0) {
544 					h_errno = HOST_NOT_FOUND;
545 					return NS_NOTFOUND;
546 				}
547 				strncpy(hostbuf, name, MAXDNAME);
548 				hostbuf[MAXDNAME] = '\0';
549 				bp = hostbuf + MAXDNAME;
550 				len = sizeof hostbuf - MAXDNAME;
551 				host.h_name = hostbuf;
552 				host.h_aliases = host_aliases;
553 				host_aliases[0] = NULL;
554 				h_addr_ptrs[0] = (char *)host_addr;
555 				h_addr_ptrs[1] = NULL;
556 				host.h_addr_list = h_addr_ptrs;
557 				if (_res.options & RES_USE_INET6)
558 					_map_v4v6_hostent(&host, &bp, &len);
559 				h_errno = NETDB_SUCCESS;
560 				*(struct hostent **)rval = &host;
561 				return NS_SUCCESS;
562 			}
563 			if (!isdigit((unsigned char)*cp) && *cp != '.')
564 				break;
565 		}
566 	if ((isxdigit((unsigned char)name[0]) && strchr(name, ':') != NULL) ||
567 	    name[0] == ':')
568 		for (cp = name;; ++cp) {
569 			if (!*cp) {
570 				if (*--cp == '.')
571 					break;
572 				/*
573 				 * All-IPv6-legal, no dot at the end.
574 				 * Fake up a hostent as if we'd actually
575 				 * done a lookup.
576 				 */
577 				if (inet_pton(af, name, host_addr) <= 0) {
578 					h_errno = HOST_NOT_FOUND;
579 					return NS_NOTFOUND;
580 				}
581 				strncpy(hostbuf, name, MAXDNAME);
582 				hostbuf[MAXDNAME] = '\0';
583 				bp = hostbuf + MAXDNAME;
584 				len = sizeof hostbuf - MAXDNAME;
585 				host.h_name = hostbuf;
586 				host.h_aliases = host_aliases;
587 				host_aliases[0] = NULL;
588 				h_addr_ptrs[0] = (char *)host_addr;
589 				h_addr_ptrs[1] = NULL;
590 				host.h_addr_list = h_addr_ptrs;
591 				h_errno = NETDB_SUCCESS;
592 				*(struct hostent **)rval = &host;
593 				return NS_SUCCESS;
594 			}
595 			if (!isxdigit((unsigned char)*cp) && *cp != ':' && *cp != '.')
596 				break;
597 		}
598 
599 	if ((n = res_search(name, C_IN, type, buf.buf, sizeof(buf))) < 0) {
600 		dprintf("res_search failed (%d)\n", n);
601 		return NS_UNAVAIL;
602 	}
603 	*(struct hostent **)rval = gethostanswer(&buf, n, name, type);
604 	return (*(struct hostent **)rval != NULL) ? NS_SUCCESS : NS_NOTFOUND;
605 }
606 
607 int
608 _dns_gethostbyaddr(void *rval, void *cb_data, va_list ap)
609 {
610 	const char *addr;	/* XXX should have been def'd as u_char! */
611 	int len, af;
612 	const u_char *uaddr;
613 	static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
614 	static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
615 	int n, size;
616 	querybuf buf;
617 	struct hostent *hp;
618 	char qbuf[MAXDNAME+1], *qp;
619 #ifdef SUNSECURITY
620 	struct hostent *rhp;
621 	char **haddr;
622 	u_long old_options;
623 	char hname2[MAXDNAME+1];
624 #endif /*SUNSECURITY*/
625 
626 	addr = va_arg(ap, const char *);
627 	uaddr = (const u_char *)addr;
628 	len = va_arg(ap, int);
629 	af = va_arg(ap, int);
630 
631 	*(struct hostent **)rval = NULL;
632 
633 	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
634 		h_errno = NETDB_INTERNAL;
635 		return NS_UNAVAIL;
636 	}
637 	if (af == AF_INET6 && len == IN6ADDRSZ &&
638 	    (!bcmp(uaddr, mapped, sizeof mapped) ||
639 	     !bcmp(uaddr, tunnelled, sizeof tunnelled))) {
640 		/* Unmap. */
641 		addr += sizeof mapped;
642 		uaddr += sizeof mapped;
643 		af = AF_INET;
644 		len = INADDRSZ;
645 	}
646 	switch (af) {
647 	case AF_INET:
648 		size = INADDRSZ;
649 		break;
650 	case AF_INET6:
651 		size = IN6ADDRSZ;
652 		break;
653 	default:
654 		errno = EAFNOSUPPORT;
655 		h_errno = NETDB_INTERNAL;
656 		return NS_UNAVAIL;
657 	}
658 	if (size != len) {
659 		errno = EINVAL;
660 		h_errno = NETDB_INTERNAL;
661 		return NS_UNAVAIL;
662 	}
663 	switch (af) {
664 	case AF_INET:
665 		(void) sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
666 			       (uaddr[3] & 0xff),
667 			       (uaddr[2] & 0xff),
668 			       (uaddr[1] & 0xff),
669 			       (uaddr[0] & 0xff));
670 		break;
671 	case AF_INET6:
672 		qp = qbuf;
673 		for (n = IN6ADDRSZ - 1; n >= 0; n--) {
674 			qp += SPRINTF((qp, "%x.%x.",
675 				       uaddr[n] & 0xf,
676 				       (uaddr[n] >> 4) & 0xf));
677 		}
678 		strcpy(qp, "ip6.int");
679 		break;
680 	default:
681 		abort();
682 	}
683 	n = res_query(qbuf, C_IN, T_PTR, (u_char *)buf.buf, sizeof buf.buf);
684 	if (n < 0) {
685 		dprintf("res_query failed (%d)\n", n);
686 		return NS_UNAVAIL;
687 	}
688 	if (n > sizeof buf.buf) {
689 		dprintf("static buffer is too small (%d)\n", n);
690 		return NS_UNAVAIL;
691 	}
692 	if (!(hp = gethostanswer(&buf, n, qbuf, T_PTR)))
693 		return NS_NOTFOUND;   /* h_errno was set by gethostanswer() */
694 #ifdef SUNSECURITY
695 	if (af == AF_INET) {
696 	    /*
697 	     * turn off search as the name should be absolute,
698 	     * 'localhost' should be matched by defnames
699 	     */
700 	    strncpy(hname2, hp->h_name, MAXDNAME);
701 	    hname2[MAXDNAME] = '\0';
702 	    old_options = _res.options;
703 	    _res.options &= ~RES_DNSRCH;
704 	    _res.options |= RES_DEFNAMES;
705 	    if (!(rhp = gethostbyname(hname2))) {
706 		syslog(LOG_NOTICE|LOG_AUTH,
707 		       "gethostbyaddr: No A record for %s (verifying [%s])",
708 		       hname2, inet_ntoa(*((struct in_addr *)addr)));
709 		_res.options = old_options;
710 		h_errno = HOST_NOT_FOUND;
711 		return NS_NOTFOUND;
712 	    }
713 	    _res.options = old_options;
714 	    for (haddr = rhp->h_addr_list; *haddr; haddr++)
715 		if (!memcmp(*haddr, addr, INADDRSZ))
716 			break;
717 	    if (!*haddr) {
718 		syslog(LOG_NOTICE|LOG_AUTH,
719 		       "gethostbyaddr: A record of %s != PTR record [%s]",
720 		       hname2, inet_ntoa(*((struct in_addr *)addr)));
721 		h_errno = HOST_NOT_FOUND;
722 		return NS_NOTFOUND;
723 	    }
724 	}
725 #endif /*SUNSECURITY*/
726 	hp->h_addrtype = af;
727 	hp->h_length = len;
728 	bcopy(addr, host_addr, len);
729 	h_addr_ptrs[0] = (char *)host_addr;
730 	h_addr_ptrs[1] = NULL;
731 	if (af == AF_INET && (_res.options & RES_USE_INET6)) {
732 		_map_v4v6_address((char*)host_addr, (char*)host_addr);
733 		hp->h_addrtype = AF_INET6;
734 		hp->h_length = IN6ADDRSZ;
735 	}
736 	h_errno = NETDB_SUCCESS;
737 	*(struct hostent **)rval = hp;
738 	return (hp != NULL) ? NS_SUCCESS : NS_NOTFOUND;
739 }
740 
741 #ifdef RESOLVSORT
742 static void
743 addrsort(ap, num)
744 	char **ap;
745 	int num;
746 {
747 	int i, j;
748 	char **p;
749 	short aval[MAXADDRS];
750 	int needsort = 0;
751 
752 	p = ap;
753 	for (i = 0; i < num; i++, p++) {
754 	    for (j = 0 ; (unsigned)j < _res.nsort; j++)
755 		if (_res.sort_list[j].addr.s_addr ==
756 		    (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
757 			break;
758 	    aval[i] = j;
759 	    if (needsort == 0 && i > 0 && j < aval[i-1])
760 		needsort = i;
761 	}
762 	if (!needsort)
763 	    return;
764 
765 	while (needsort < num) {
766 	    for (j = needsort - 1; j >= 0; j--) {
767 		if (aval[j] > aval[j+1]) {
768 		    char *hp;
769 
770 		    i = aval[j];
771 		    aval[j] = aval[j+1];
772 		    aval[j+1] = i;
773 
774 		    hp = ap[j];
775 		    ap[j] = ap[j+1];
776 		    ap[j+1] = hp;
777 
778 		} else
779 		    break;
780 	    }
781 	    needsort++;
782 	}
783 }
784 #endif
785 void
786 _sethostdnsent(stayopen)
787 	int stayopen;
788 {
789 	if ((_res.options & RES_INIT) == 0 && res_init() == -1)
790 		return;
791 	if (stayopen)
792 		_res.options |= RES_STAYOPEN | RES_USEVC;
793 }
794 
795 void
796 _endhostdnsent()
797 {
798 	_res.options &= ~(RES_STAYOPEN | RES_USEVC);
799 	res_close();
800 }
801