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1 /*	$NetBSD: gethnamaddr.c,v 1.70 2006/03/22 00:03:51 christos Exp $	*/
2 
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 #include <sys/cdefs.h>
55 #include <sys/types.h>
56 
57 #include <sys/param.h>
58 #include <sys/socket.h>
59 #include <sys/un.h>
60 #include <netinet/in.h>
61 #include <arpa/inet.h>
62 #include "arpa_nameser.h"
63 #include "resolv_private.h"
64 #include "resolv_cache.h"
65 #include <assert.h>
66 #include <ctype.h>
67 #include <errno.h>
68 #include <netdb.h>
69 #include <stdarg.h>
70 #include <stdio.h>
71 #include <strings.h>
72 #include <syslog.h>
73 #include <unistd.h>
74 
75 #ifndef LOG_AUTH
76 # define LOG_AUTH 0
77 #endif
78 
79 #define MULTI_PTRS_ARE_ALIASES 1	/* XXX - experimental */
80 
81 #include "nsswitch.h"
82 #include <stdlib.h>
83 #include <string.h>
84 
85 // This should be synchronized to ResponseCode.h
86 static const int DnsProxyQueryResult = 222;
87 
88 static const char const AskedForGot[] =
89 			  "gethostby*.getanswer: asked for \"%s\", got \"%s\"";
90 
91 #define	MAXPACKET	(64*1024)
92 
93 typedef union {
94     HEADER hdr;
95     u_char buf[MAXPACKET];
96 } querybuf;
97 
98 typedef union {
99     int32_t al;
100     char ac;
101 } align;
102 
103 #ifdef DEBUG
104 static void dprintf(const char *, res_state, ...)
105 	__attribute__((__format__(__printf__, 1, 3)));
106 #endif
107 static struct hostent *getanswer(const querybuf *, int, const char *, int,
108     res_state);
109 static void map_v4v6_address(const char *, char *);
110 static void map_v4v6_hostent(struct hostent *, char **, char *);
111 static void addrsort(char **, int, res_state);
112 
113 static void _sethtent(int);
114 static void _endhtent(void);
115 static struct hostent *_gethtent(void);
116 void ht_sethostent(int);
117 void ht_endhostent(void);
118 struct hostent *ht_gethostbyname(char *);
119 struct hostent *ht_gethostbyaddr(const char *, int, int);
120 void dns_service(void);
121 #undef dn_skipname
122 int dn_skipname(const u_char *, const u_char *);
123 static int _gethtbyaddr(void *, void *, va_list);
124 static int _gethtbyname(void *, void *, va_list);
125 static struct hostent *_gethtbyname2(const char *, int);
126 static int _dns_gethtbyaddr(void *, void *, va_list);
127 static int _dns_gethtbyname(void *, void *, va_list);
128 
129 static struct hostent *gethostbyname_internal(const char *, int, res_state, const char *);
130 
131 static const ns_src default_dns_files[] = {
132 	{ NSSRC_FILES, 	NS_SUCCESS },
133 	{ NSSRC_DNS, 	NS_SUCCESS },
134 	{ 0, 0 }
135 };
136 
137 
138 #ifdef DEBUG
139 static void
dprintf(const char * msg,res_state res,...)140 dprintf(const char *msg, res_state res, ...)
141 {
142 	assert(msg != NULL);
143 
144 	if (res->options & RES_DEBUG) {
145 		int save = errno;
146 		va_list ap;
147 
148 		va_start (ap, res);
149 		vprintf(msg, ap);
150 		va_end (ap);
151 
152 		errno = save;
153 	}
154 }
155 #else
156 # define dprintf(msg, res, num) ((void)0) /*nada*/
157 #endif
158 
159 #define BOUNDED_INCR(x) \
160 	do { \
161 		cp += (x); \
162 		if (cp > eom) { \
163 			h_errno = NO_RECOVERY; \
164 			return NULL; \
165 		} \
166 	} while (/*CONSTCOND*/0)
167 
168 #define BOUNDS_CHECK(ptr, count) \
169 	do { \
170 		if ((ptr) + (count) > eom) { \
171 			h_errno = NO_RECOVERY; \
172 			return NULL; \
173 		} \
174 	} while (/*CONSTCOND*/0)
175 
176 static struct hostent *
getanswer(const querybuf * answer,int anslen,const char * qname,int qtype,res_state res)177 getanswer(const querybuf *answer, int anslen, const char *qname, int qtype,
178     res_state res)
179 {
180 	const HEADER *hp;
181 	const u_char *cp;
182 	int n;
183 	const u_char *eom, *erdata;
184 	char *bp, **ap, **hap, *ep;
185 	int type, class, ancount, qdcount;
186 	int haveanswer, had_error;
187 	int toobig = 0;
188 	char tbuf[MAXDNAME];
189 	const char *tname;
190 	int (*name_ok)(const char *);
191 	res_static  rs = __res_get_static();
192 
193 	assert(answer != NULL);
194 	assert(qname != NULL);
195 
196 	tname = qname;
197 	rs->host.h_name = NULL;
198 	eom = answer->buf + anslen;
199 	switch (qtype) {
200 	case T_A:
201 	case T_AAAA:
202 		name_ok = res_hnok;
203 		break;
204 	case T_PTR:
205 		name_ok = res_dnok;
206 		break;
207 	default:
208 		return NULL;	/* XXX should be abort(); */
209 	}
210 	/*
211 	 * find first satisfactory answer
212 	 */
213 	hp = &answer->hdr;
214 	ancount = ntohs(hp->ancount);
215 	qdcount = ntohs(hp->qdcount);
216 	bp = rs->hostbuf;
217 	ep = rs->hostbuf + sizeof rs->hostbuf;
218 	cp = answer->buf;
219 	BOUNDED_INCR(HFIXEDSZ);
220 	if (qdcount != 1) {
221 		h_errno = NO_RECOVERY;
222 		return NULL;
223 	}
224 	n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
225 	if ((n < 0) || !(*name_ok)(bp)) {
226 		h_errno = NO_RECOVERY;
227 		return NULL;
228 	}
229 	BOUNDED_INCR(n + QFIXEDSZ);
230 	if (qtype == T_A || qtype == T_AAAA) {
231 		/* res_send() has already verified that the query name is the
232 		 * same as the one we sent; this just gets the expanded name
233 		 * (i.e., with the succeeding search-domain tacked on).
234 		 */
235 		n = strlen(bp) + 1;		/* for the \0 */
236 		if (n >= MAXHOSTNAMELEN) {
237 			h_errno = NO_RECOVERY;
238 			return NULL;
239 		}
240 		rs->host.h_name = bp;
241 		bp += n;
242 		/* The qname can be abbreviated, but h_name is now absolute. */
243 		qname = rs->host.h_name;
244 	}
245 	ap = rs->host_aliases;
246 	*ap = NULL;
247 	rs->host.h_aliases = rs->host_aliases;
248 	hap = rs->h_addr_ptrs;
249 	*hap = NULL;
250 	rs->host.h_addr_list = rs->h_addr_ptrs;
251 	haveanswer = 0;
252 	had_error = 0;
253 	while (ancount-- > 0 && cp < eom && !had_error) {
254 		n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
255 		if ((n < 0) || !(*name_ok)(bp)) {
256 			had_error++;
257 			continue;
258 		}
259 		cp += n;			/* name */
260 		BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
261 		type = _getshort(cp);
262  		cp += INT16SZ;			/* type */
263 		class = _getshort(cp);
264  		cp += INT16SZ + INT32SZ;	/* class, TTL */
265 		n = _getshort(cp);
266 		cp += INT16SZ;			/* len */
267 		BOUNDS_CHECK(cp, n);
268 		erdata = cp + n;
269 		if (class != C_IN) {
270 			/* XXX - debug? syslog? */
271 			cp += n;
272 			continue;		/* XXX - had_error++ ? */
273 		}
274 		if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
275 			if (ap >= &rs->host_aliases[MAXALIASES-1])
276 				continue;
277 			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
278 			if ((n < 0) || !(*name_ok)(tbuf)) {
279 				had_error++;
280 				continue;
281 			}
282 			cp += n;
283 			if (cp != erdata) {
284 				h_errno = NO_RECOVERY;
285 				return NULL;
286 			}
287 			/* Store alias. */
288 			*ap++ = bp;
289 			n = strlen(bp) + 1;	/* for the \0 */
290 			if (n >= MAXHOSTNAMELEN) {
291 				had_error++;
292 				continue;
293 			}
294 			bp += n;
295 			/* Get canonical name. */
296 			n = strlen(tbuf) + 1;	/* for the \0 */
297 			if (n > ep - bp || n >= MAXHOSTNAMELEN) {
298 				had_error++;
299 				continue;
300 			}
301 			strlcpy(bp, tbuf, (size_t)(ep - bp));
302 			rs->host.h_name = bp;
303 			bp += n;
304 			continue;
305 		}
306 		if (qtype == T_PTR && type == T_CNAME) {
307 			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
308 			if (n < 0 || !res_dnok(tbuf)) {
309 				had_error++;
310 				continue;
311 			}
312 			cp += n;
313 			if (cp != erdata) {
314 				h_errno = NO_RECOVERY;
315 				return NULL;
316 			}
317 			/* Get canonical name. */
318 			n = strlen(tbuf) + 1;	/* for the \0 */
319 			if (n > ep - bp || n >= MAXHOSTNAMELEN) {
320 				had_error++;
321 				continue;
322 			}
323 			strlcpy(bp, tbuf, (size_t)(ep - bp));
324 			tname = bp;
325 			bp += n;
326 			continue;
327 		}
328 		if (type != qtype) {
329 			if (type != T_KEY && type != T_SIG)
330 				syslog(LOG_NOTICE|LOG_AUTH,
331 	       "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
332 				       qname, p_class(C_IN), p_type(qtype),
333 				       p_type(type));
334 			cp += n;
335 			continue;		/* XXX - had_error++ ? */
336 		}
337 		switch (type) {
338 		case T_PTR:
339 			if (strcasecmp(tname, bp) != 0) {
340 				syslog(LOG_NOTICE|LOG_AUTH,
341 				       AskedForGot, qname, bp);
342 				cp += n;
343 				continue;	/* XXX - had_error++ ? */
344 			}
345 			n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
346 			if ((n < 0) || !res_hnok(bp)) {
347 				had_error++;
348 				break;
349 			}
350 #if MULTI_PTRS_ARE_ALIASES
351 			cp += n;
352 			if (cp != erdata) {
353 				h_errno = NO_RECOVERY;
354 				return NULL;
355 			}
356 			if (!haveanswer)
357 				rs->host.h_name = bp;
358 			else if (ap < &rs->host_aliases[MAXALIASES-1])
359 				*ap++ = bp;
360 			else
361 				n = -1;
362 			if (n != -1) {
363 				n = strlen(bp) + 1;	/* for the \0 */
364 				if (n >= MAXHOSTNAMELEN) {
365 					had_error++;
366 					break;
367 				}
368 				bp += n;
369 			}
370 			break;
371 #else
372 			rs->host.h_name = bp;
373 			if (res->options & RES_USE_INET6) {
374 				n = strlen(bp) + 1;	/* for the \0 */
375 				if (n >= MAXHOSTNAMELEN) {
376 					had_error++;
377 					break;
378 				}
379 				bp += n;
380 				map_v4v6_hostent(&rs->host, &bp, ep);
381 			}
382 			h_errno = NETDB_SUCCESS;
383 			return &rs->host;
384 #endif
385 		case T_A:
386 		case T_AAAA:
387 			if (strcasecmp(rs->host.h_name, bp) != 0) {
388 				syslog(LOG_NOTICE|LOG_AUTH,
389 				       AskedForGot, rs->host.h_name, bp);
390 				cp += n;
391 				continue;	/* XXX - had_error++ ? */
392 			}
393 			if (n != rs->host.h_length) {
394 				cp += n;
395 				continue;
396 			}
397 			if (type == T_AAAA) {
398 				struct in6_addr in6;
399 				memcpy(&in6, cp, IN6ADDRSZ);
400 				if (IN6_IS_ADDR_V4MAPPED(&in6)) {
401 					cp += n;
402 					continue;
403 				}
404 			}
405 			if (!haveanswer) {
406 				int nn;
407 
408 				rs->host.h_name = bp;
409 				nn = strlen(bp) + 1;	/* for the \0 */
410 				bp += nn;
411 			}
412 
413 			bp += sizeof(align) -
414 			    (size_t)((u_long)bp % sizeof(align));
415 
416 			if (bp + n >= &rs->hostbuf[sizeof rs->hostbuf]) {
417 				dprintf("size (%d) too big\n", res, n);
418 				had_error++;
419 				continue;
420 			}
421 			if (hap >= &rs->h_addr_ptrs[MAXADDRS-1]) {
422 				if (!toobig++)
423 					dprintf("Too many addresses (%d)\n",
424 						res, MAXADDRS);
425 				cp += n;
426 				continue;
427 			}
428 			(void)memcpy(*hap++ = bp, cp, (size_t)n);
429 			bp += n;
430 			cp += n;
431 			if (cp != erdata) {
432 				h_errno = NO_RECOVERY;
433 				return NULL;
434 			}
435 			break;
436 		default:
437 			abort();
438 		}
439 		if (!had_error)
440 			haveanswer++;
441 	}
442 	if (haveanswer) {
443 		*ap = NULL;
444 		*hap = NULL;
445 		/*
446 		 * Note: we sort even if host can take only one address
447 		 * in its return structures - should give it the "best"
448 		 * address in that case, not some random one
449 		 */
450 		if (res->nsort && haveanswer > 1 && qtype == T_A)
451 			addrsort(rs->h_addr_ptrs, haveanswer, res);
452 		if (!rs->host.h_name) {
453 			n = strlen(qname) + 1;	/* for the \0 */
454 			if (n > ep - bp || n >= MAXHOSTNAMELEN)
455 				goto no_recovery;
456 			strlcpy(bp, qname, (size_t)(ep - bp));
457 			rs->host.h_name = bp;
458 			bp += n;
459 		}
460 		if (res->options & RES_USE_INET6)
461 			map_v4v6_hostent(&rs->host, &bp, ep);
462 		h_errno = NETDB_SUCCESS;
463 		return &rs->host;
464 	}
465  no_recovery:
466 	h_errno = NO_RECOVERY;
467 	return NULL;
468 }
469 
470 int
gethostbyname_r(const char * name,struct hostent * hp,char * buf,size_t buflen,struct hostent ** result,int * errorp)471 gethostbyname_r(const char *name, struct hostent *hp, char *buf, size_t buflen,
472     struct hostent**result, int *errorp)
473 {
474         struct hostent *res;
475 
476         res = gethostbyname(name);
477         *errorp = h_errno;
478         if (res == NULL) {
479                 *result = NULL;
480                 return -1;
481         }
482         memcpy(hp, res, sizeof *hp);
483         *result = hp;
484         return 0;
485 }
486 
487 struct hostent *
gethostbyname(const char * name)488 gethostbyname(const char *name)
489 {
490 	struct hostent *hp;
491 	res_state res = __res_get_state();
492 
493 	if (res == NULL)
494 		return NULL;
495 
496 	assert(name != NULL);
497 
498 	/* try IPv6 first - if that fails do IPv4 */
499 	if (res->options & RES_USE_INET6) {
500 		hp = gethostbyname_internal(name, AF_INET6, res, NULL);
501 		if (hp) {
502 			__res_put_state(res);
503 			return hp;
504 		}
505 	}
506 	hp = gethostbyname_internal(name, AF_INET, res, NULL);
507 	__res_put_state(res);
508 	return hp;
509 }
510 
511 struct hostent *
gethostbyname2(const char * name,int af)512 gethostbyname2(const char *name, int af)
513 {
514 	return android_gethostbynameforiface(name, af, NULL);
515 }
516 
517 struct hostent *
android_gethostbynameforiface(const char * name,int af,const char * iface)518 android_gethostbynameforiface(const char *name, int af, const char *iface)
519 {
520 	struct hostent *hp;
521 	res_state res = __res_get_state();
522 
523 	if (res == NULL)
524 		return NULL;
525 	hp = gethostbyname_internal(name, af, res, iface);
526 	__res_put_state(res);
527 	return hp;
528 }
529 
530 
android_open_proxy()531 static FILE* android_open_proxy()
532 {
533 	int sock;
534 	const int one = 1;
535 	struct sockaddr_un proxy_addr;
536 
537 	sock = socket(AF_UNIX, SOCK_STREAM, 0);
538 	if (sock < 0) {
539 		return NULL;
540 	}
541 
542 	setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
543 	memset(&proxy_addr, 0, sizeof(proxy_addr));
544 	proxy_addr.sun_family = AF_UNIX;
545 	strlcpy(proxy_addr.sun_path, "/dev/socket/dnsproxyd", sizeof(proxy_addr.sun_path));
546 	if (TEMP_FAILURE_RETRY(connect(sock,
547 			(const struct sockaddr*) &proxy_addr,
548 			sizeof(proxy_addr))) != 0) {
549 		close(sock);
550 		return NULL;
551 	}
552 
553 	return fdopen(sock, "r+");
554 }
555 
556 static struct hostent *
android_read_hostent(FILE * proxy)557 android_read_hostent(FILE* proxy)
558 {
559 	uint32_t size;
560 	char buf[4];
561 	if (fread(buf, 1, sizeof(buf), proxy) != sizeof(buf)) return NULL;
562 
563 	/* This is reading serialized data from system/netd/DnsProxyListener.cpp
564 	 * and changes here need to be matched there */
565 	int result_code = strtol(buf, NULL, 10);
566 	if (result_code != DnsProxyQueryResult) {
567 		fread(&size, 1, sizeof(size), proxy);
568 		return NULL;
569 	}
570 
571 	if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
572 	size = ntohl(size);
573 	res_static rs = __res_get_static();
574 	memset(&rs->host, 0, sizeof(rs->host));
575 	char *ptr = rs->hostbuf;
576 
577 	if (fread(ptr, 1, size, proxy) != size) return NULL;
578 	ptr += size;
579 	rs->host.h_name = rs->hostbuf;
580 
581 	char **aliases = rs->host_aliases;
582 	rs->host.h_aliases = rs->host_aliases;
583 	while (1) {
584 		if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
585 		size = ntohl(size);
586 
587 		if (size == 0) {
588 			*aliases = NULL;
589 			break;
590 		}
591 		if (fread(ptr, 1, size, proxy) != size) return NULL;
592 		*aliases++ = ptr;
593 		ptr += size;
594 	}
595 
596 	if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
597 	rs->host.h_addrtype = ntohl(size);
598 
599 	if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
600 	rs->host.h_length = ntohl(size);
601 
602 	char **addrs = rs->h_addr_ptrs;
603 	rs->host.h_addr_list = rs->h_addr_ptrs;
604 	while (1) {
605 		if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
606 		size = ntohl(size);
607 		if (size == 0) {
608 			*addrs = NULL;
609 			break;
610 		}
611 		if (fread(ptr, 1, size, proxy) != size) return NULL;
612 		*addrs++ = ptr;
613 		ptr += size;
614 	}
615 
616 	return &rs->host;
617 }
618 
619 
620 static struct hostent *
gethostbyname_internal_real(const char * name,int af,res_state res)621 gethostbyname_internal_real(const char *name, int af, res_state res)
622 {
623 	const char *cp;
624 	char *bp, *ep;
625 	int size;
626 	struct hostent *hp;
627 	res_static rs = __res_get_static();
628 
629 	static const ns_dtab dtab[] = {
630 		NS_FILES_CB(_gethtbyname, NULL)
631 		{ NSSRC_DNS, _dns_gethtbyname, NULL },	/* force -DHESIOD */
632 		{ 0, 0, 0 }
633 	};
634 
635 	assert(name != NULL);
636 
637 	switch (af) {
638 	case AF_INET:
639 		size = INADDRSZ;
640 		break;
641 	case AF_INET6:
642 		size = IN6ADDRSZ;
643 		break;
644 	default:
645 		h_errno = NETDB_INTERNAL;
646 		errno = EAFNOSUPPORT;
647 		return NULL;
648 	}
649 
650 	rs->host.h_addrtype = af;
651 	rs->host.h_length = size;
652 
653 	/*
654 	 * if there aren't any dots, it could be a user-level alias.
655 	 * this is also done in res_nquery() since we are not the only
656 	 * function that looks up host names.
657 	 */
658 	if (!strchr(name, '.') && (cp = __hostalias(name)))
659 		name = cp;
660 
661 	/*
662 	 * disallow names consisting only of digits/dots, unless
663 	 * they end in a dot.
664 	 */
665 	if (isdigit((u_char) name[0]))
666 		for (cp = name;; ++cp) {
667 			if (!*cp) {
668 				if (*--cp == '.')
669 					break;
670 				/*
671 				 * All-numeric, no dot at the end.
672 				 * Fake up a hostent as if we'd actually
673 				 * done a lookup.
674 				 */
675 				if (inet_pton(af, name,
676 				    (char *)(void *)rs->host_addr) <= 0) {
677 					h_errno = HOST_NOT_FOUND;
678 					return NULL;
679 				}
680 				strncpy(rs->hostbuf, name, MAXDNAME);
681 				rs->hostbuf[MAXDNAME] = '\0';
682 				bp = rs->hostbuf + MAXDNAME;
683 				ep = rs->hostbuf + sizeof rs->hostbuf;
684 				rs->host.h_name = rs->hostbuf;
685 				rs->host.h_aliases = rs->host_aliases;
686 				rs->host_aliases[0] = NULL;
687 				rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
688 				rs->h_addr_ptrs[1] = NULL;
689 				rs->host.h_addr_list = rs->h_addr_ptrs;
690 				if (res->options & RES_USE_INET6)
691 					map_v4v6_hostent(&rs->host, &bp, ep);
692 				h_errno = NETDB_SUCCESS;
693 				return &rs->host;
694 			}
695 			if (!isdigit((u_char) *cp) && *cp != '.')
696 				break;
697 		}
698 	if ((isxdigit((u_char) name[0]) && strchr(name, ':') != NULL) ||
699 	    name[0] == ':')
700 		for (cp = name;; ++cp) {
701 			if (!*cp) {
702 				if (*--cp == '.')
703 					break;
704 				/*
705 				 * All-IPv6-legal, no dot at the end.
706 				 * Fake up a hostent as if we'd actually
707 				 * done a lookup.
708 				 */
709 				if (inet_pton(af, name,
710 				    (char *)(void *)rs->host_addr) <= 0) {
711 					h_errno = HOST_NOT_FOUND;
712 					return NULL;
713 				}
714 				strncpy(rs->hostbuf, name, MAXDNAME);
715 				rs->hostbuf[MAXDNAME] = '\0';
716 				bp = rs->hostbuf + MAXDNAME;
717 				ep = rs->hostbuf + sizeof rs->hostbuf;
718 				rs->host.h_name = rs->hostbuf;
719 				rs->host.h_aliases = rs->host_aliases;
720 				rs->host_aliases[0] = NULL;
721 				rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
722 				rs->h_addr_ptrs[1] = NULL;
723 				rs->host.h_addr_list = rs->h_addr_ptrs;
724 				h_errno = NETDB_SUCCESS;
725 				return &rs->host;
726 			}
727 			if (!isxdigit((u_char) *cp) && *cp != ':' && *cp != '.')
728 				break;
729 		}
730 
731 	hp = NULL;
732 	h_errno = NETDB_INTERNAL;
733 	if (nsdispatch(&hp, dtab, NSDB_HOSTS, "gethostbyname",
734 	    default_dns_files, name, strlen(name), af) != NS_SUCCESS) {
735 		return NULL;
736 	}
737 	h_errno = NETDB_SUCCESS;
738 	return hp;
739 }
740 
741 
742 // very similar in proxy-ness to android_getaddrinfo_proxy
743 static struct hostent *
gethostbyname_internal(const char * name,int af,res_state res,const char * iface)744 gethostbyname_internal(const char *name, int af, res_state res, const char *iface)
745 {
746 	const char *cache_mode = getenv("ANDROID_DNS_MODE");
747 	FILE* proxy = NULL;
748 	struct hostent *result = NULL;
749 
750 	if (cache_mode != NULL && strcmp(cache_mode, "local") == 0) {
751 		res_setiface(res, iface);
752 		return gethostbyname_internal_real(name, af, res);
753 	}
754 
755 	proxy = android_open_proxy();
756 	if (proxy == NULL) goto exit;
757 
758 	/* This is writing to system/netd/DnsProxyListener.cpp and changes
759 	 * here need to be matched there */
760 	if (fprintf(proxy, "gethostbyname %s %s %d",
761 			iface == NULL ? "^" : iface,
762 			name == NULL ? "^" : name,
763 			af) < 0) {
764 		goto exit;
765 	}
766 
767 	if (fputc(0, proxy) == EOF || fflush(proxy) != 0) {
768 		goto exit;
769 	}
770 
771 	result = android_read_hostent(proxy);
772 
773 exit:
774 	if (proxy != NULL) {
775 		fclose(proxy);
776 	}
777 	return result;
778 }
779 
780 
781 struct hostent *
android_gethostbyaddrforiface_proxy(const void * addr,socklen_t len,int af,const char * iface)782 android_gethostbyaddrforiface_proxy(const void *addr,
783     socklen_t len, int af, const char* iface)
784 {
785 	struct hostent *result = NULL;
786 	FILE* proxy = android_open_proxy();
787 
788 	if (proxy == NULL) goto exit;
789 
790 	char buf[INET6_ADDRSTRLEN];  //big enough for IPv4 and IPv6
791 	const char * addrStr = inet_ntop(af, addr, buf, sizeof(buf));
792 	if (addrStr == NULL) goto exit;
793 
794 	if (fprintf(proxy, "gethostbyaddr %s %d %d %s",
795 			addrStr, len, af, iface == NULL ? "^" : iface) < 0) {
796 		goto exit;
797 	}
798 
799 	if (fputc(0, proxy) == EOF || fflush(proxy) != 0) {
800 		goto exit;
801 	}
802 
803 	result = android_read_hostent(proxy);
804 exit:
805 	if (proxy != NULL) {
806 		fclose(proxy);
807 	}
808 	return result;
809 }
810 
811 struct hostent *
android_gethostbyaddrforiface_real(const void * addr,socklen_t len,int af,const char * iface)812 android_gethostbyaddrforiface_real(const void *addr,
813     socklen_t len, int af, const char* iface)
814 {
815 	const u_char *uaddr = (const u_char *)addr;
816 	socklen_t size;
817 	struct hostent *hp;
818 	static const ns_dtab dtab[] = {
819 		NS_FILES_CB(_gethtbyaddr, NULL)
820 		{ NSSRC_DNS, _dns_gethtbyaddr, NULL },	/* force -DHESIOD */
821 		{ 0, 0, 0 }
822 	};
823 
824 	assert(addr != NULL);
825 
826 	if (af == AF_INET6 && len == IN6ADDRSZ &&
827 	    (IN6_IS_ADDR_LINKLOCAL((const struct in6_addr *)(const void *)uaddr) ||
828 	     IN6_IS_ADDR_SITELOCAL((const struct in6_addr *)(const void *)uaddr))) {
829 		h_errno = HOST_NOT_FOUND;
830 		return NULL;
831 	}
832 	if (af == AF_INET6 && len == IN6ADDRSZ &&
833 	    (IN6_IS_ADDR_V4MAPPED((const struct in6_addr *)(const void *)uaddr) ||
834 	     IN6_IS_ADDR_V4COMPAT((const struct in6_addr *)(const void *)uaddr))) {
835 		/* Unmap. */
836 		addr += IN6ADDRSZ - INADDRSZ;
837 		uaddr += IN6ADDRSZ - INADDRSZ;
838 		af = AF_INET;
839 		len = INADDRSZ;
840 	}
841 	switch (af) {
842 	case AF_INET:
843 		size = INADDRSZ;
844 		break;
845 	case AF_INET6:
846 		size = IN6ADDRSZ;
847 		break;
848 	default:
849 		errno = EAFNOSUPPORT;
850 		h_errno = NETDB_INTERNAL;
851 		return NULL;
852 	}
853 	if (size != len) {
854 		errno = EINVAL;
855 		h_errno = NETDB_INTERNAL;
856 		return NULL;
857 	}
858 	hp = NULL;
859 	h_errno = NETDB_INTERNAL;
860 	if (nsdispatch(&hp, dtab, NSDB_HOSTS, "gethostbyaddr",
861 	    default_dns_files, uaddr, len, af, iface) != NS_SUCCESS)
862 		return NULL;
863 	h_errno = NETDB_SUCCESS;
864 	return hp;
865 }
866 
867 struct hostent *
android_gethostbyaddrforiface(const void * addr,socklen_t len,int af,const char * iface)868 android_gethostbyaddrforiface(const void *addr, socklen_t len, int af, const char* iface)
869 {
870 	const char *cache_mode = getenv("ANDROID_DNS_MODE");
871 
872 	if (cache_mode == NULL || strcmp(cache_mode, "local") != 0) {
873 		return android_gethostbyaddrforiface_proxy(addr, len, af, iface);
874 	} else {
875 		return android_gethostbyaddrforiface_real(addr,len, af,iface);
876 	}
877 }
878 
879 struct hostent *
gethostbyaddr(const void * addr,socklen_t len,int af)880 gethostbyaddr(const void *addr, socklen_t len, int af)
881 {
882 	return android_gethostbyaddrforiface(addr, len, af, NULL);
883 }
884 
885 
886 static void
_sethtent(int f)887 _sethtent(int f)
888 {
889     res_static  rs = __res_get_static();
890     if (rs == NULL) return;
891 	if (!rs->hostf)
892 		rs->hostf = fopen(_PATH_HOSTS, "r" );
893 	else
894 		rewind(rs->hostf);
895 	rs->stayopen = f;
896 }
897 
898 static void
_endhtent(void)899 _endhtent(void)
900 {
901     res_static  rs = __res_get_static();
902     if (rs == NULL) return;
903 
904 	if (rs->hostf && !rs->stayopen) {
905 		(void) fclose(rs->hostf);
906 		rs->hostf = NULL;
907 	}
908 }
909 
910 static struct hostent *
_gethtent(void)911 _gethtent(void)
912 {
913 	char *p;
914 	char *cp, **q;
915 	int af, len;
916 	res_static  rs = __res_get_static();
917 
918 	if (!rs->hostf && !(rs->hostf = fopen(_PATH_HOSTS, "r" ))) {
919 		h_errno = NETDB_INTERNAL;
920 		return NULL;
921 	}
922  again:
923 	if (!(p = fgets(rs->hostbuf, sizeof rs->hostbuf, rs->hostf))) {
924 		h_errno = HOST_NOT_FOUND;
925 		return NULL;
926 	}
927 	if (*p == '#')
928 		goto again;
929 	if (!(cp = strpbrk(p, "#\n")))
930 		goto again;
931 	*cp = '\0';
932 	if (!(cp = strpbrk(p, " \t")))
933 		goto again;
934 	*cp++ = '\0';
935 	if (inet_pton(AF_INET6, p, (char *)(void *)rs->host_addr) > 0) {
936 		af = AF_INET6;
937 		len = IN6ADDRSZ;
938 	} else if (inet_pton(AF_INET, p, (char *)(void *)rs->host_addr) > 0) {
939 		res_state res = __res_get_state();
940 		if (res == NULL)
941 			return NULL;
942 		if (res->options & RES_USE_INET6) {
943 			map_v4v6_address((char *)(void *)rs->host_addr,
944 			    (char *)(void *)rs->host_addr);
945 			af = AF_INET6;
946 			len = IN6ADDRSZ;
947 		} else {
948 			af = AF_INET;
949 			len = INADDRSZ;
950 		}
951 		__res_put_state(res);
952 	} else {
953 		goto again;
954 	}
955 	/* if this is not something we're looking for, skip it. */
956 	if (rs->host.h_addrtype != 0 && rs->host.h_addrtype != af)
957 		goto again;
958 	if (rs->host.h_length != 0 && rs->host.h_length != len)
959 		goto again;
960 	rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
961 	rs->h_addr_ptrs[1] = NULL;
962 	rs->host.h_addr_list = rs->h_addr_ptrs;
963 	rs->host.h_length = len;
964 	rs->host.h_addrtype = af;
965 	while (*cp == ' ' || *cp == '\t')
966 		cp++;
967 	rs->host.h_name = cp;
968 	q = rs->host.h_aliases = rs->host_aliases;
969 	if ((cp = strpbrk(cp, " \t")) != NULL)
970 		*cp++ = '\0';
971 	while (cp && *cp) {
972 		if (*cp == ' ' || *cp == '\t') {
973 			cp++;
974 			continue;
975 		}
976 		if (q < &rs->host_aliases[MAXALIASES - 1])
977 			*q++ = cp;
978 		if ((cp = strpbrk(cp, " \t")) != NULL)
979 			*cp++ = '\0';
980 	}
981 	*q = NULL;
982 	h_errno = NETDB_SUCCESS;
983 	return &rs->host;
984 }
985 
986 /*ARGSUSED*/
987 int
_gethtbyname(void * rv,void * cb_data,va_list ap)988 _gethtbyname(void *rv, void *cb_data, va_list ap)
989 {
990 	struct hostent *hp;
991 	const char *name;
992 	int af;
993 
994 	assert(rv != NULL);
995 
996 	name = va_arg(ap, char *);
997 	/* NOSTRICT skip len */(void)va_arg(ap, int);
998 	af = va_arg(ap, int);
999 
1000 	hp = NULL;
1001 #if 0
1002 	{
1003 		res_state res = __res_get_state();
1004 		if (res == NULL)
1005 			return NS_NOTFOUND;
1006 		if (res->options & RES_USE_INET6)
1007 			hp = _gethtbyname2(name, AF_INET6);
1008 		if (hp==NULL)
1009 			hp = _gethtbyname2(name, AF_INET);
1010 		__res_put_state(res);
1011 	}
1012 #else
1013 	hp = _gethtbyname2(name, af);
1014 #endif
1015 	*((struct hostent **)rv) = hp;
1016 	if (hp == NULL) {
1017 		h_errno = HOST_NOT_FOUND;
1018 		return NS_NOTFOUND;
1019 	}
1020 	return NS_SUCCESS;
1021 }
1022 
1023 static struct hostent *
_gethtbyname2(const char * name,int af)1024 _gethtbyname2(const char *name, int af)
1025 {
1026 	struct hostent *p;
1027 	char *tmpbuf, *ptr, **cp;
1028 	int num;
1029 	size_t len;
1030 	res_static rs = __res_get_static();
1031 
1032 	assert(name != NULL);
1033 
1034 	_sethtent(rs->stayopen);
1035 	ptr = tmpbuf = NULL;
1036 	num = 0;
1037 	while ((p = _gethtent()) != NULL && num < MAXADDRS) {
1038 		if (p->h_addrtype != af)
1039 			continue;
1040 		if (strcasecmp(p->h_name, name) != 0) {
1041 			for (cp = p->h_aliases; *cp != NULL; cp++)
1042 				if (strcasecmp(*cp, name) == 0)
1043 					break;
1044 			if (*cp == NULL) continue;
1045 		}
1046 
1047 		if (num == 0) {
1048 			size_t bufsize;
1049 			char *src;
1050 
1051 			bufsize = strlen(p->h_name) + 2 +
1052 				  MAXADDRS * p->h_length +
1053 				  ALIGNBYTES;
1054 			for (cp = p->h_aliases; *cp != NULL; cp++)
1055 				bufsize += strlen(*cp) + 1;
1056 
1057 			if ((tmpbuf = malloc(bufsize)) == NULL) {
1058 				h_errno = NETDB_INTERNAL;
1059 				return NULL;
1060 			}
1061 
1062 			ptr = tmpbuf;
1063 			src = p->h_name;
1064 			while ((*ptr++ = *src++) != '\0');
1065 			for (cp = p->h_aliases; *cp != NULL; cp++) {
1066 				src = *cp;
1067 				while ((*ptr++ = *src++) != '\0');
1068 			}
1069 			*ptr++ = '\0';
1070 
1071 			ptr = (char *)(void *)ALIGN(ptr);
1072 		}
1073 
1074 		(void)memcpy(ptr, p->h_addr_list[0], (size_t)p->h_length);
1075 		ptr += p->h_length;
1076 		num++;
1077 	}
1078 	_endhtent();
1079 	if (num == 0) return NULL;
1080 
1081 	len = ptr - tmpbuf;
1082 	if (len > (sizeof(rs->hostbuf) - ALIGNBYTES)) {
1083 		free(tmpbuf);
1084 		errno = ENOSPC;
1085 		h_errno = NETDB_INTERNAL;
1086 		return NULL;
1087 	}
1088 	ptr = memcpy((void *)ALIGN(rs->hostbuf), tmpbuf, len);
1089 	free(tmpbuf);
1090 
1091 	rs->host.h_name = ptr;
1092 	while (*ptr++);
1093 
1094 	cp = rs->host_aliases;
1095 	while (*ptr) {
1096 		*cp++ = ptr;
1097 		while (*ptr++);
1098 	}
1099 	ptr++;
1100 	*cp = NULL;
1101 
1102 	ptr = (char *)(void *)ALIGN(ptr);
1103 	cp = rs->h_addr_ptrs;
1104 	while (num--) {
1105 		*cp++ = ptr;
1106 		ptr += rs->host.h_length;
1107 	}
1108 	*cp = NULL;
1109 
1110 	return &rs->host;
1111 }
1112 
1113 /*ARGSUSED*/
1114 static int
_gethtbyaddr(void * rv,void * cb_data,va_list ap)1115 _gethtbyaddr(void *rv, void *cb_data, va_list ap)
1116 {
1117 	struct hostent *p;
1118 	const unsigned char *addr;
1119 	int len, af;
1120 	res_static  rs = __res_get_static();
1121 
1122 	assert(rv != NULL);
1123 
1124 	addr = va_arg(ap, unsigned char *);
1125 	len = va_arg(ap, int);
1126 	af = va_arg(ap, int);
1127 
1128 	rs->host.h_length = len;
1129 	rs->host.h_addrtype = af;
1130 
1131 	_sethtent(rs->stayopen);
1132 	while ((p = _gethtent()) != NULL)
1133 		if (p->h_addrtype == af && !memcmp(p->h_addr, addr,
1134 		    (size_t)len))
1135 			break;
1136 	_endhtent();
1137 	*((struct hostent **)rv) = p;
1138 	if (p==NULL) {
1139 		h_errno = HOST_NOT_FOUND;
1140 		return NS_NOTFOUND;
1141 	}
1142 	return NS_SUCCESS;
1143 }
1144 
1145 static void
map_v4v6_address(const char * src,char * dst)1146 map_v4v6_address(const char *src, char *dst)
1147 {
1148 	u_char *p = (u_char *)dst;
1149 	char tmp[INADDRSZ];
1150 	int i;
1151 
1152 	assert(src != NULL);
1153 	assert(dst != NULL);
1154 
1155 	/* Stash a temporary copy so our caller can update in place. */
1156 	(void)memcpy(tmp, src, INADDRSZ);
1157 	/* Mark this ipv6 addr as a mapped ipv4. */
1158 	for (i = 0; i < 10; i++)
1159 		*p++ = 0x00;
1160 	*p++ = 0xff;
1161 	*p++ = 0xff;
1162 	/* Retrieve the saved copy and we're done. */
1163 	(void)memcpy((void *)p, tmp, INADDRSZ);
1164 }
1165 
1166 static void
map_v4v6_hostent(struct hostent * hp,char ** bpp,char * ep)1167 map_v4v6_hostent(struct hostent *hp, char **bpp, char *ep)
1168 {
1169 	char **ap;
1170 
1171 	assert(hp != NULL);
1172 	assert(bpp != NULL);
1173 	assert(ep != NULL);
1174 
1175 	if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
1176 		return;
1177 	hp->h_addrtype = AF_INET6;
1178 	hp->h_length = IN6ADDRSZ;
1179 	for (ap = hp->h_addr_list; *ap; ap++) {
1180 		int i = sizeof(align) - (size_t)((u_long)*bpp % sizeof(align));
1181 
1182 		if (ep - *bpp < (i + IN6ADDRSZ)) {
1183 			/* Out of memory.  Truncate address list here.  XXX */
1184 			*ap = NULL;
1185 			return;
1186 		}
1187 		*bpp += i;
1188 		map_v4v6_address(*ap, *bpp);
1189 		*ap = *bpp;
1190 		*bpp += IN6ADDRSZ;
1191 	}
1192 }
1193 
1194 static void
addrsort(char ** ap,int num,res_state res)1195 addrsort(char **ap, int num, res_state res)
1196 {
1197 	int i, j;
1198 	char **p;
1199 	short aval[MAXADDRS];
1200 	int needsort = 0;
1201 
1202 	assert(ap != NULL);
1203 
1204 	p = ap;
1205 	for (i = 0; i < num; i++, p++) {
1206 	    for (j = 0 ; (unsigned)j < res->nsort; j++)
1207 		if (res->sort_list[j].addr.s_addr ==
1208 		    (((struct in_addr *)(void *)(*p))->s_addr &
1209 		    res->sort_list[j].mask))
1210 			break;
1211 	    aval[i] = j;
1212 	    if (needsort == 0 && i > 0 && j < aval[i-1])
1213 		needsort = i;
1214 	}
1215 	if (!needsort)
1216 	    return;
1217 
1218 	while (needsort < num) {
1219 	    for (j = needsort - 1; j >= 0; j--) {
1220 		if (aval[j] > aval[j+1]) {
1221 		    char *hp;
1222 
1223 		    i = aval[j];
1224 		    aval[j] = aval[j+1];
1225 		    aval[j+1] = i;
1226 
1227 		    hp = ap[j];
1228 		    ap[j] = ap[j+1];
1229 		    ap[j+1] = hp;
1230 		} else
1231 		    break;
1232 	    }
1233 	    needsort++;
1234 	}
1235 }
1236 
1237 struct hostent *
gethostent(void)1238 gethostent(void)
1239 {
1240     res_static  rs = __res_get_static();
1241 	rs->host.h_addrtype = 0;
1242 	rs->host.h_length = 0;
1243 	return _gethtent();
1244 }
1245 
1246 /*ARGSUSED*/
1247 static int
_dns_gethtbyname(void * rv,void * cb_data,va_list ap)1248 _dns_gethtbyname(void *rv, void *cb_data, va_list ap)
1249 {
1250 	querybuf *buf;
1251 	int n, type;
1252 	struct hostent *hp;
1253 	const char *name;
1254 	int af;
1255 	res_state res;
1256 
1257 	assert(rv != NULL);
1258 
1259 	name = va_arg(ap, char *);
1260 	/* NOSTRICT skip len */(void)va_arg(ap, int);
1261 	af = va_arg(ap, int);
1262 
1263 	switch (af) {
1264 	case AF_INET:
1265 		type = T_A;
1266 		break;
1267 	case AF_INET6:
1268 		type = T_AAAA;
1269 		break;
1270 	default:
1271 		return NS_UNAVAIL;
1272 	}
1273 	buf = malloc(sizeof(*buf));
1274 	if (buf == NULL) {
1275 		h_errno = NETDB_INTERNAL;
1276 		return NS_NOTFOUND;
1277 	}
1278 	res = __res_get_state();
1279 	if (res == NULL) {
1280 		free(buf);
1281 		return NS_NOTFOUND;
1282 	}
1283 	n = res_nsearch(res, name, C_IN, type, buf->buf, sizeof(buf->buf));
1284 	if (n < 0) {
1285 		free(buf);
1286 		dprintf("res_nsearch failed (%d)\n", res, n);
1287 		__res_put_state(res);
1288 		return NS_NOTFOUND;
1289 	}
1290 	hp = getanswer(buf, n, name, type, res);
1291 	free(buf);
1292 	__res_put_state(res);
1293 	if (hp == NULL)
1294 		switch (h_errno) {
1295 		case HOST_NOT_FOUND:
1296 			return NS_NOTFOUND;
1297 		case TRY_AGAIN:
1298 			return NS_TRYAGAIN;
1299 		default:
1300 			return NS_UNAVAIL;
1301 		}
1302 	*((struct hostent **)rv) = hp;
1303 	return NS_SUCCESS;
1304 }
1305 
1306 /*ARGSUSED*/
1307 static int
_dns_gethtbyaddr(void * rv,void * cb_data,va_list ap)1308 _dns_gethtbyaddr(void *rv, void	*cb_data, va_list ap)
1309 {
1310 	char qbuf[MAXDNAME + 1], *qp, *ep;
1311 	int n;
1312 	querybuf *buf;
1313 	struct hostent *hp;
1314 	const unsigned char *uaddr;
1315 	int len, af, advance;
1316 	res_state res;
1317 	const char* iface;
1318 	res_static rs = __res_get_static();
1319 
1320 	assert(rv != NULL);
1321 
1322 	uaddr = va_arg(ap, unsigned char *);
1323 	len = va_arg(ap, int);
1324 	af = va_arg(ap, int);
1325 	iface = va_arg(ap, char *);
1326 
1327 	switch (af) {
1328 	case AF_INET:
1329 		(void)snprintf(qbuf, sizeof(qbuf), "%u.%u.%u.%u.in-addr.arpa",
1330 		    (uaddr[3] & 0xff), (uaddr[2] & 0xff),
1331 		    (uaddr[1] & 0xff), (uaddr[0] & 0xff));
1332 		break;
1333 
1334 	case AF_INET6:
1335 		qp = qbuf;
1336 		ep = qbuf + sizeof(qbuf) - 1;
1337 		for (n = IN6ADDRSZ - 1; n >= 0; n--) {
1338 			advance = snprintf(qp, (size_t)(ep - qp), "%x.%x.",
1339 			    uaddr[n] & 0xf,
1340 			    ((unsigned int)uaddr[n] >> 4) & 0xf);
1341 			if (advance > 0 && qp + advance < ep)
1342 				qp += advance;
1343 			else {
1344 				h_errno = NETDB_INTERNAL;
1345 				return NS_NOTFOUND;
1346 			}
1347 		}
1348 		if (strlcat(qbuf, "ip6.arpa", sizeof(qbuf)) >= sizeof(qbuf)) {
1349 			h_errno = NETDB_INTERNAL;
1350 			return NS_NOTFOUND;
1351 		}
1352 		break;
1353 	default:
1354 		abort();
1355 	}
1356 
1357 	buf = malloc(sizeof(*buf));
1358 	if (buf == NULL) {
1359 		h_errno = NETDB_INTERNAL;
1360 		return NS_NOTFOUND;
1361 	}
1362 	res = __res_get_state();
1363 	if (res == NULL) {
1364 		free(buf);
1365 		return NS_NOTFOUND;
1366 	}
1367 	res_setiface(res, iface);
1368 	n = res_nquery(res, qbuf, C_IN, T_PTR, buf->buf, sizeof(buf->buf));
1369 	if (n < 0) {
1370 		free(buf);
1371 		dprintf("res_nquery failed (%d)\n", res, n);
1372 		__res_put_state(res);
1373 		return NS_NOTFOUND;
1374 	}
1375 	hp = getanswer(buf, n, qbuf, T_PTR, res);
1376 	free(buf);
1377 	if (hp == NULL) {
1378 		__res_put_state(res);
1379 		switch (h_errno) {
1380 		case HOST_NOT_FOUND:
1381 			return NS_NOTFOUND;
1382 		case TRY_AGAIN:
1383 			return NS_TRYAGAIN;
1384 		default:
1385 			return NS_UNAVAIL;
1386 		}
1387 	}
1388 	hp->h_addrtype = af;
1389 	hp->h_length = len;
1390 	(void)memcpy(rs->host_addr, uaddr, (size_t)len);
1391 	rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
1392 	rs->h_addr_ptrs[1] = NULL;
1393 	if (af == AF_INET && (res->options & RES_USE_INET6)) {
1394 		map_v4v6_address((char *)(void *)rs->host_addr,
1395 		    (char *)(void *)rs->host_addr);
1396 		hp->h_addrtype = AF_INET6;
1397 		hp->h_length = IN6ADDRSZ;
1398 	}
1399 
1400 	__res_put_state(res);
1401 	*((struct hostent **)rv) = hp;
1402 	h_errno = NETDB_SUCCESS;
1403 	return NS_SUCCESS;
1404 }
1405