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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 "NetdClientDispatch.h"
     64 #include "resolv_netid.h"
     65 #include "resolv_private.h"
     66 #include "resolv_cache.h"
     67 #include <assert.h>
     68 #include <ctype.h>
     69 #include <errno.h>
     70 #include <netdb.h>
     71 #include <stdarg.h>
     72 #include <stdio.h>
     73 #include <strings.h>
     74 #include <syslog.h>
     75 #include <unistd.h>
     76 
     77 #define ALIGNBYTES (sizeof(uintptr_t) - 1)
     78 #define ALIGN(p) (((uintptr_t)(p) + ALIGNBYTES) &~ ALIGNBYTES)
     79 
     80 #ifndef LOG_AUTH
     81 # define LOG_AUTH 0
     82 #endif
     83 
     84 #define MULTI_PTRS_ARE_ALIASES 1	/* XXX - experimental */
     85 
     86 #include "nsswitch.h"
     87 #include <stdlib.h>
     88 #include <string.h>
     89 
     90 // This should be synchronized to ResponseCode.h
     91 static const int DnsProxyQueryResult = 222;
     92 
     93 static const char AskedForGot[] =
     94 			  "gethostby*.getanswer: asked for \"%s\", got \"%s\"";
     95 
     96 #define	MAXPACKET	(64*1024)
     97 
     98 typedef union {
     99     HEADER hdr;
    100     u_char buf[MAXPACKET];
    101 } querybuf;
    102 
    103 typedef union {
    104     int32_t al;
    105     char ac;
    106 } align;
    107 
    108 #ifdef DEBUG
    109 static void dprintf(const char *, res_state, ...)
    110 	__attribute__((__format__(__printf__, 1, 3)));
    111 #endif
    112 static struct hostent *getanswer(const querybuf *, int, const char *, int,
    113     res_state);
    114 static void map_v4v6_address(const char *, char *);
    115 static void map_v4v6_hostent(struct hostent *, char **, char *);
    116 static void addrsort(char **, int, res_state);
    117 
    118 static void _sethtent(int);
    119 static void _endhtent(void);
    120 static struct hostent *_gethtent(void);
    121 void ht_sethostent(int);
    122 void ht_endhostent(void);
    123 struct hostent *ht_gethostbyname(char *);
    124 struct hostent *ht_gethostbyaddr(const char *, int, int);
    125 void dns_service(void);
    126 #undef dn_skipname
    127 int dn_skipname(const u_char *, const u_char *);
    128 static int _gethtbyaddr(void *, void *, va_list);
    129 static int _gethtbyname(void *, void *, va_list);
    130 static struct hostent *_gethtbyname2(const char *, int);
    131 static int _dns_gethtbyaddr(void *, void *, va_list);
    132 static int _dns_gethtbyname(void *, void *, va_list);
    133 
    134 static struct hostent *gethostbyname_internal(const char *, int, res_state, unsigned, unsigned);
    135 
    136 static const ns_src default_dns_files[] = {
    137 	{ NSSRC_FILES, 	NS_SUCCESS },
    138 	{ NSSRC_DNS, 	NS_SUCCESS },
    139 	{ 0, 0 }
    140 };
    141 
    142 
    143 #ifdef DEBUG
    144 static void
    145 dprintf(const char *msg, res_state res, ...)
    146 {
    147 	assert(msg != NULL);
    148 
    149 	if (res->options & RES_DEBUG) {
    150 		int save = errno;
    151 		va_list ap;
    152 
    153 		va_start (ap, res);
    154 		vprintf(msg, ap);
    155 		va_end (ap);
    156 
    157 		errno = save;
    158 	}
    159 }
    160 #else
    161 # define dprintf(msg, res, num) ((void)0) /*nada*/
    162 #endif
    163 
    164 #define BOUNDED_INCR(x) \
    165 	do { \
    166 		cp += (x); \
    167 		if (cp > eom) { \
    168 			h_errno = NO_RECOVERY; \
    169 			return NULL; \
    170 		} \
    171 	} while (/*CONSTCOND*/0)
    172 
    173 #define BOUNDS_CHECK(ptr, count) \
    174 	do { \
    175 		if ((ptr) + (count) > eom) { \
    176 			h_errno = NO_RECOVERY; \
    177 			return NULL; \
    178 		} \
    179 	} while (/*CONSTCOND*/0)
    180 
    181 static struct hostent *
    182 getanswer(const querybuf *answer, int anslen, const char *qname, int qtype,
    183     res_state res)
    184 {
    185 	const HEADER *hp;
    186 	const u_char *cp;
    187 	int n;
    188 	const u_char *eom, *erdata;
    189 	char *bp, **ap, **hap, *ep;
    190 	int type, class, ancount, qdcount;
    191 	int haveanswer, had_error;
    192 	int toobig = 0;
    193 	char tbuf[MAXDNAME];
    194 	const char *tname;
    195 	int (*name_ok)(const char *);
    196 	res_static  rs = __res_get_static();
    197 
    198 	assert(answer != NULL);
    199 	assert(qname != NULL);
    200 
    201 	tname = qname;
    202 	rs->host.h_name = NULL;
    203 	eom = answer->buf + anslen;
    204 	switch (qtype) {
    205 	case T_A:
    206 	case T_AAAA:
    207 		name_ok = res_hnok;
    208 		break;
    209 	case T_PTR:
    210 		name_ok = res_dnok;
    211 		break;
    212 	default:
    213 		return NULL;	/* XXX should be abort(); */
    214 	}
    215 	/*
    216 	 * find first satisfactory answer
    217 	 */
    218 	hp = &answer->hdr;
    219 	ancount = ntohs(hp->ancount);
    220 	qdcount = ntohs(hp->qdcount);
    221 	bp = rs->hostbuf;
    222 	ep = rs->hostbuf + sizeof rs->hostbuf;
    223 	cp = answer->buf;
    224 	BOUNDED_INCR(HFIXEDSZ);
    225 	if (qdcount != 1) {
    226 		h_errno = NO_RECOVERY;
    227 		return NULL;
    228 	}
    229 	n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
    230 	if ((n < 0) || !(*name_ok)(bp)) {
    231 		h_errno = NO_RECOVERY;
    232 		return NULL;
    233 	}
    234 	BOUNDED_INCR(n + QFIXEDSZ);
    235 	if (qtype == T_A || qtype == T_AAAA) {
    236 		/* res_send() has already verified that the query name is the
    237 		 * same as the one we sent; this just gets the expanded name
    238 		 * (i.e., with the succeeding search-domain tacked on).
    239 		 */
    240 		n = strlen(bp) + 1;		/* for the \0 */
    241 		if (n >= MAXHOSTNAMELEN) {
    242 			h_errno = NO_RECOVERY;
    243 			return NULL;
    244 		}
    245 		rs->host.h_name = bp;
    246 		bp += n;
    247 		/* The qname can be abbreviated, but h_name is now absolute. */
    248 		qname = rs->host.h_name;
    249 	}
    250 	ap = rs->host_aliases;
    251 	*ap = NULL;
    252 	rs->host.h_aliases = rs->host_aliases;
    253 	hap = rs->h_addr_ptrs;
    254 	*hap = NULL;
    255 	rs->host.h_addr_list = rs->h_addr_ptrs;
    256 	haveanswer = 0;
    257 	had_error = 0;
    258 	while (ancount-- > 0 && cp < eom && !had_error) {
    259 		n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
    260 		if ((n < 0) || !(*name_ok)(bp)) {
    261 			had_error++;
    262 			continue;
    263 		}
    264 		cp += n;			/* name */
    265 		BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
    266 		type = _getshort(cp);
    267  		cp += INT16SZ;			/* type */
    268 		class = _getshort(cp);
    269  		cp += INT16SZ + INT32SZ;	/* class, TTL */
    270 		n = _getshort(cp);
    271 		cp += INT16SZ;			/* len */
    272 		BOUNDS_CHECK(cp, n);
    273 		erdata = cp + n;
    274 		if (class != C_IN) {
    275 			/* XXX - debug? syslog? */
    276 			cp += n;
    277 			continue;		/* XXX - had_error++ ? */
    278 		}
    279 		if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
    280 			if (ap >= &rs->host_aliases[MAXALIASES-1])
    281 				continue;
    282 			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
    283 			if ((n < 0) || !(*name_ok)(tbuf)) {
    284 				had_error++;
    285 				continue;
    286 			}
    287 			cp += n;
    288 			if (cp != erdata) {
    289 				h_errno = NO_RECOVERY;
    290 				return NULL;
    291 			}
    292 			/* Store alias. */
    293 			*ap++ = bp;
    294 			n = strlen(bp) + 1;	/* for the \0 */
    295 			if (n >= MAXHOSTNAMELEN) {
    296 				had_error++;
    297 				continue;
    298 			}
    299 			bp += n;
    300 			/* Get canonical name. */
    301 			n = strlen(tbuf) + 1;	/* for the \0 */
    302 			if (n > ep - bp || n >= MAXHOSTNAMELEN) {
    303 				had_error++;
    304 				continue;
    305 			}
    306 			strlcpy(bp, tbuf, (size_t)(ep - bp));
    307 			rs->host.h_name = bp;
    308 			bp += n;
    309 			continue;
    310 		}
    311 		if (qtype == T_PTR && type == T_CNAME) {
    312 			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
    313 			if (n < 0 || !res_dnok(tbuf)) {
    314 				had_error++;
    315 				continue;
    316 			}
    317 			cp += n;
    318 			if (cp != erdata) {
    319 				h_errno = NO_RECOVERY;
    320 				return NULL;
    321 			}
    322 			/* Get canonical name. */
    323 			n = strlen(tbuf) + 1;	/* for the \0 */
    324 			if (n > ep - bp || n >= MAXHOSTNAMELEN) {
    325 				had_error++;
    326 				continue;
    327 			}
    328 			strlcpy(bp, tbuf, (size_t)(ep - bp));
    329 			tname = bp;
    330 			bp += n;
    331 			continue;
    332 		}
    333 		if (type != qtype) {
    334 			if (type != T_KEY && type != T_SIG)
    335 				syslog(LOG_NOTICE|LOG_AUTH,
    336 	       "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
    337 				       qname, p_class(C_IN), p_type(qtype),
    338 				       p_type(type));
    339 			cp += n;
    340 			continue;		/* XXX - had_error++ ? */
    341 		}
    342 		switch (type) {
    343 		case T_PTR:
    344 			if (strcasecmp(tname, bp) != 0) {
    345 				syslog(LOG_NOTICE|LOG_AUTH,
    346 				       AskedForGot, qname, bp);
    347 				cp += n;
    348 				continue;	/* XXX - had_error++ ? */
    349 			}
    350 			n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
    351 			if ((n < 0) || !res_hnok(bp)) {
    352 				had_error++;
    353 				break;
    354 			}
    355 #if MULTI_PTRS_ARE_ALIASES
    356 			cp += n;
    357 			if (cp != erdata) {
    358 				h_errno = NO_RECOVERY;
    359 				return NULL;
    360 			}
    361 			if (!haveanswer)
    362 				rs->host.h_name = bp;
    363 			else if (ap < &rs->host_aliases[MAXALIASES-1])
    364 				*ap++ = bp;
    365 			else
    366 				n = -1;
    367 			if (n != -1) {
    368 				n = strlen(bp) + 1;	/* for the \0 */
    369 				if (n >= MAXHOSTNAMELEN) {
    370 					had_error++;
    371 					break;
    372 				}
    373 				bp += n;
    374 			}
    375 			break;
    376 #else
    377 			rs->host.h_name = bp;
    378 			if (res->options & RES_USE_INET6) {
    379 				n = strlen(bp) + 1;	/* for the \0 */
    380 				if (n >= MAXHOSTNAMELEN) {
    381 					had_error++;
    382 					break;
    383 				}
    384 				bp += n;
    385 				map_v4v6_hostent(&rs->host, &bp, ep);
    386 			}
    387 			h_errno = NETDB_SUCCESS;
    388 			return &rs->host;
    389 #endif
    390 		case T_A:
    391 		case T_AAAA:
    392 			if (strcasecmp(rs->host.h_name, bp) != 0) {
    393 				syslog(LOG_NOTICE|LOG_AUTH,
    394 				       AskedForGot, rs->host.h_name, bp);
    395 				cp += n;
    396 				continue;	/* XXX - had_error++ ? */
    397 			}
    398 			if (n != rs->host.h_length) {
    399 				cp += n;
    400 				continue;
    401 			}
    402 			if (type == T_AAAA) {
    403 				struct in6_addr in6;
    404 				memcpy(&in6, cp, IN6ADDRSZ);
    405 				if (IN6_IS_ADDR_V4MAPPED(&in6)) {
    406 					cp += n;
    407 					continue;
    408 				}
    409 			}
    410 			if (!haveanswer) {
    411 				int nn;
    412 
    413 				rs->host.h_name = bp;
    414 				nn = strlen(bp) + 1;	/* for the \0 */
    415 				bp += nn;
    416 			}
    417 
    418 			bp += sizeof(align) -
    419 			    (size_t)((u_long)bp % sizeof(align));
    420 
    421 			if (bp + n >= &rs->hostbuf[sizeof rs->hostbuf]) {
    422 				dprintf("size (%d) too big\n", res, n);
    423 				had_error++;
    424 				continue;
    425 			}
    426 			if (hap >= &rs->h_addr_ptrs[MAXADDRS-1]) {
    427 				if (!toobig++)
    428 					dprintf("Too many addresses (%d)\n",
    429 						res, MAXADDRS);
    430 				cp += n;
    431 				continue;
    432 			}
    433 			(void)memcpy(*hap++ = bp, cp, (size_t)n);
    434 			bp += n;
    435 			cp += n;
    436 			if (cp != erdata) {
    437 				h_errno = NO_RECOVERY;
    438 				return NULL;
    439 			}
    440 			break;
    441 		default:
    442 			abort();
    443 		}
    444 		if (!had_error)
    445 			haveanswer++;
    446 	}
    447 	if (haveanswer) {
    448 		*ap = NULL;
    449 		*hap = NULL;
    450 		/*
    451 		 * Note: we sort even if host can take only one address
    452 		 * in its return structures - should give it the "best"
    453 		 * address in that case, not some random one
    454 		 */
    455 		if (res->nsort && haveanswer > 1 && qtype == T_A)
    456 			addrsort(rs->h_addr_ptrs, haveanswer, res);
    457 		if (!rs->host.h_name) {
    458 			n = strlen(qname) + 1;	/* for the \0 */
    459 			if (n > ep - bp || n >= MAXHOSTNAMELEN)
    460 				goto no_recovery;
    461 			strlcpy(bp, qname, (size_t)(ep - bp));
    462 			rs->host.h_name = bp;
    463 			bp += n;
    464 		}
    465 		if (res->options & RES_USE_INET6)
    466 			map_v4v6_hostent(&rs->host, &bp, ep);
    467 		h_errno = NETDB_SUCCESS;
    468 		return &rs->host;
    469 	}
    470  no_recovery:
    471 	h_errno = NO_RECOVERY;
    472 	return NULL;
    473 }
    474 
    475 int
    476 gethostbyname_r(const char *name, struct hostent *hp, char *buf, size_t buflen,
    477     struct hostent**result, int *errorp)
    478 {
    479         struct hostent *res;
    480 
    481         res = gethostbyname(name);
    482         *errorp = h_errno;
    483         if (res == NULL) {
    484                 *result = NULL;
    485                 return -1;
    486         }
    487         memcpy(hp, res, sizeof *hp);
    488         *result = hp;
    489         return 0;
    490 }
    491 
    492 struct hostent *
    493 gethostbyname(const char *name)
    494 {
    495 	struct hostent *hp;
    496 	res_state res = __res_get_state();
    497 
    498 	if (res == NULL)
    499 		return NULL;
    500 
    501 	assert(name != NULL);
    502 
    503 	/* try IPv6 first - if that fails do IPv4 */
    504 	if (res->options & RES_USE_INET6) {
    505 		hp = gethostbyname_internal(name, AF_INET6, res, NETID_UNSET, MARK_UNSET);
    506 		if (hp) {
    507 			__res_put_state(res);
    508 			return hp;
    509 		}
    510 	}
    511 	hp = gethostbyname_internal(name, AF_INET, res, NETID_UNSET, MARK_UNSET);
    512 	__res_put_state(res);
    513 	return hp;
    514 }
    515 
    516 struct hostent *
    517 gethostbyname2(const char *name, int af)
    518 {
    519 	return android_gethostbynamefornet(name, af, NETID_UNSET, MARK_UNSET);
    520 }
    521 
    522 struct hostent *
    523 android_gethostbynamefornet(const char *name, int af, unsigned netid, unsigned mark)
    524 {
    525 	struct hostent *hp;
    526 	res_state res = __res_get_state();
    527 
    528 	if (res == NULL)
    529 		return NULL;
    530 	hp = gethostbyname_internal(name, af, res, netid, mark);
    531 	__res_put_state(res);
    532 	return hp;
    533 }
    534 
    535 
    536 static FILE* android_open_proxy()
    537 {
    538 	int sock;
    539 	const int one = 1;
    540 	struct sockaddr_un proxy_addr;
    541 
    542 	sock = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
    543 	if (sock < 0) {
    544 		return NULL;
    545 	}
    546 
    547 	setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
    548 	memset(&proxy_addr, 0, sizeof(proxy_addr));
    549 	proxy_addr.sun_family = AF_UNIX;
    550 	strlcpy(proxy_addr.sun_path, "/dev/socket/dnsproxyd", sizeof(proxy_addr.sun_path));
    551 	if (TEMP_FAILURE_RETRY(connect(sock,
    552 			(const struct sockaddr*) &proxy_addr,
    553 			sizeof(proxy_addr))) != 0) {
    554 		close(sock);
    555 		return NULL;
    556 	}
    557 
    558 	return fdopen(sock, "r+");
    559 }
    560 
    561 static struct hostent *
    562 android_read_hostent(FILE* proxy)
    563 {
    564 	uint32_t size;
    565 	char buf[4];
    566 	if (fread(buf, 1, sizeof(buf), proxy) != sizeof(buf)) return NULL;
    567 
    568 	/* This is reading serialized data from system/netd/server/DnsProxyListener.cpp
    569 	 * and changes here need to be matched there */
    570 	int result_code = strtol(buf, NULL, 10);
    571 	if (result_code != DnsProxyQueryResult) {
    572 		fread(&size, 1, sizeof(size), proxy);
    573 		return NULL;
    574 	}
    575 
    576 	if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
    577 	size = ntohl(size);
    578 	res_static rs = __res_get_static();
    579 	memset(&rs->host, 0, sizeof(rs->host));
    580 	char *ptr = rs->hostbuf;
    581 
    582 	if (fread(ptr, 1, size, proxy) != size) return NULL;
    583 	ptr += size;
    584 	rs->host.h_name = rs->hostbuf;
    585 
    586 	char **aliases = rs->host_aliases;
    587 	rs->host.h_aliases = rs->host_aliases;
    588 	while (1) {
    589 		if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
    590 		size = ntohl(size);
    591 
    592 		if (size == 0) {
    593 			*aliases = NULL;
    594 			break;
    595 		}
    596 		if (fread(ptr, 1, size, proxy) != size) return NULL;
    597 		*aliases++ = ptr;
    598 		ptr += size;
    599 	}
    600 
    601 	if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
    602 	rs->host.h_addrtype = ntohl(size);
    603 
    604 	if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
    605 	rs->host.h_length = ntohl(size);
    606 
    607 	char **addrs = rs->h_addr_ptrs;
    608 	rs->host.h_addr_list = rs->h_addr_ptrs;
    609 	while (1) {
    610 		if (fread(&size, 1, sizeof(size), proxy) != sizeof(size)) return NULL;
    611 		size = ntohl(size);
    612 		if (size == 0) {
    613 			*addrs = NULL;
    614 			break;
    615 		}
    616 		if (fread(ptr, 1, size, proxy) != size) return NULL;
    617 		*addrs++ = ptr;
    618 		ptr += size;
    619 	}
    620 
    621 	return &rs->host;
    622 }
    623 
    624 
    625 static struct hostent *
    626 gethostbyname_internal_real(const char *name, int af, res_state res)
    627 {
    628 	const char *cp;
    629 	char *bp, *ep;
    630 	int size;
    631 	struct hostent *hp;
    632 	res_static rs = __res_get_static();
    633 
    634 	static const ns_dtab dtab[] = {
    635 		NS_FILES_CB(_gethtbyname, NULL)
    636 		{ NSSRC_DNS, _dns_gethtbyname, NULL },	/* force -DHESIOD */
    637 		{ 0, 0, 0 }
    638 	};
    639 
    640 	assert(name != NULL);
    641 
    642 	switch (af) {
    643 	case AF_INET:
    644 		size = INADDRSZ;
    645 		break;
    646 	case AF_INET6:
    647 		size = IN6ADDRSZ;
    648 		break;
    649 	default:
    650 		h_errno = NETDB_INTERNAL;
    651 		errno = EAFNOSUPPORT;
    652 		return NULL;
    653 	}
    654 
    655 	rs->host.h_addrtype = af;
    656 	rs->host.h_length = size;
    657 
    658 	/*
    659 	 * if there aren't any dots, it could be a user-level alias.
    660 	 * this is also done in res_nquery() since we are not the only
    661 	 * function that looks up host names.
    662 	 */
    663 	if (!strchr(name, '.') && (cp = __hostalias(name)))
    664 		name = cp;
    665 
    666 	/*
    667 	 * disallow names consisting only of digits/dots, unless
    668 	 * they end in a dot.
    669 	 */
    670 	if (isdigit((u_char) name[0]))
    671 		for (cp = name;; ++cp) {
    672 			if (!*cp) {
    673 				if (*--cp == '.')
    674 					break;
    675 				/*
    676 				 * All-numeric, no dot at the end.
    677 				 * Fake up a hostent as if we'd actually
    678 				 * done a lookup.
    679 				 */
    680 				if (inet_pton(af, name,
    681 				    (char *)(void *)rs->host_addr) <= 0) {
    682 					h_errno = HOST_NOT_FOUND;
    683 					return NULL;
    684 				}
    685 				strncpy(rs->hostbuf, name, MAXDNAME);
    686 				rs->hostbuf[MAXDNAME] = '\0';
    687 				bp = rs->hostbuf + MAXDNAME;
    688 				ep = rs->hostbuf + sizeof rs->hostbuf;
    689 				rs->host.h_name = rs->hostbuf;
    690 				rs->host.h_aliases = rs->host_aliases;
    691 				rs->host_aliases[0] = NULL;
    692 				rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
    693 				rs->h_addr_ptrs[1] = NULL;
    694 				rs->host.h_addr_list = rs->h_addr_ptrs;
    695 				if (res->options & RES_USE_INET6)
    696 					map_v4v6_hostent(&rs->host, &bp, ep);
    697 				h_errno = NETDB_SUCCESS;
    698 				return &rs->host;
    699 			}
    700 			if (!isdigit((u_char) *cp) && *cp != '.')
    701 				break;
    702 		}
    703 	if ((isxdigit((u_char) name[0]) && strchr(name, ':') != NULL) ||
    704 	    name[0] == ':')
    705 		for (cp = name;; ++cp) {
    706 			if (!*cp) {
    707 				if (*--cp == '.')
    708 					break;
    709 				/*
    710 				 * All-IPv6-legal, no dot at the end.
    711 				 * Fake up a hostent as if we'd actually
    712 				 * done a lookup.
    713 				 */
    714 				if (inet_pton(af, name,
    715 				    (char *)(void *)rs->host_addr) <= 0) {
    716 					h_errno = HOST_NOT_FOUND;
    717 					return NULL;
    718 				}
    719 				strncpy(rs->hostbuf, name, MAXDNAME);
    720 				rs->hostbuf[MAXDNAME] = '\0';
    721 				bp = rs->hostbuf + MAXDNAME;
    722 				ep = rs->hostbuf + sizeof rs->hostbuf;
    723 				rs->host.h_name = rs->hostbuf;
    724 				rs->host.h_aliases = rs->host_aliases;
    725 				rs->host_aliases[0] = NULL;
    726 				rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
    727 				rs->h_addr_ptrs[1] = NULL;
    728 				rs->host.h_addr_list = rs->h_addr_ptrs;
    729 				h_errno = NETDB_SUCCESS;
    730 				return &rs->host;
    731 			}
    732 			if (!isxdigit((u_char) *cp) && *cp != ':' && *cp != '.')
    733 				break;
    734 		}
    735 
    736 	hp = NULL;
    737 	h_errno = NETDB_INTERNAL;
    738 	if (nsdispatch(&hp, dtab, NSDB_HOSTS, "gethostbyname",
    739 	    default_dns_files, name, strlen(name), af) != NS_SUCCESS) {
    740 		return NULL;
    741 	}
    742 	h_errno = NETDB_SUCCESS;
    743 	return hp;
    744 }
    745 
    746 
    747 // very similar in proxy-ness to android_getaddrinfo_proxy
    748 static struct hostent *
    749 gethostbyname_internal(const char *name, int af, res_state res, unsigned netid, unsigned mark)
    750 {
    751 	const char *cache_mode = getenv("ANDROID_DNS_MODE");
    752 	FILE* proxy = NULL;
    753 	struct hostent *result = NULL;
    754 
    755 	if (cache_mode != NULL && strcmp(cache_mode, "local") == 0) {
    756 		res_setnetid(res, netid);
    757 		res_setmark(res, mark);
    758 		return gethostbyname_internal_real(name, af, res);
    759 	}
    760 
    761 	proxy = android_open_proxy();
    762 	if (proxy == NULL) goto exit;
    763 
    764 	netid = __netdClientDispatch.netIdForResolv(netid);
    765 
    766 	/* This is writing to system/netd/server/DnsProxyListener.cpp and changes
    767 	 * here need to be matched there */
    768 	if (fprintf(proxy, "gethostbyname %u %s %d",
    769 			netid,
    770 			name == NULL ? "^" : name,
    771 			af) < 0) {
    772 		goto exit;
    773 	}
    774 
    775 	if (fputc(0, proxy) == EOF || fflush(proxy) != 0) {
    776 		goto exit;
    777 	}
    778 
    779 	result = android_read_hostent(proxy);
    780 
    781 exit:
    782 	if (proxy != NULL) {
    783 		fclose(proxy);
    784 	}
    785 	return result;
    786 }
    787 
    788 
    789 struct hostent *
    790 android_gethostbyaddrfornet_proxy(const void *addr,
    791     socklen_t len, int af, unsigned netid)
    792 {
    793 	struct hostent *result = NULL;
    794 	FILE* proxy = android_open_proxy();
    795 
    796 	if (proxy == NULL) goto exit;
    797 
    798 	char buf[INET6_ADDRSTRLEN];  //big enough for IPv4 and IPv6
    799 	const char * addrStr = inet_ntop(af, addr, buf, sizeof(buf));
    800 	if (addrStr == NULL) goto exit;
    801 
    802 	netid = __netdClientDispatch.netIdForResolv(netid);
    803 
    804 	if (fprintf(proxy, "gethostbyaddr %s %d %d %u",
    805 			addrStr, len, af, netid) < 0) {
    806 		goto exit;
    807 	}
    808 
    809 	if (fputc(0, proxy) == EOF || fflush(proxy) != 0) {
    810 		goto exit;
    811 	}
    812 
    813 	result = android_read_hostent(proxy);
    814 exit:
    815 	if (proxy != NULL) {
    816 		fclose(proxy);
    817 	}
    818 	return result;
    819 }
    820 
    821 struct hostent *
    822 android_gethostbyaddrfornet_real(const void *addr,
    823     socklen_t len, int af, unsigned netid, unsigned mark)
    824 {
    825 	const u_char *uaddr = (const u_char *)addr;
    826 	socklen_t size;
    827 	struct hostent *hp;
    828 	static const ns_dtab dtab[] = {
    829 		NS_FILES_CB(_gethtbyaddr, NULL)
    830 		{ NSSRC_DNS, _dns_gethtbyaddr, NULL },	/* force -DHESIOD */
    831 		{ 0, 0, 0 }
    832 	};
    833 
    834 	assert(addr != NULL);
    835 
    836 	if (af == AF_INET6 && len == NS_IN6ADDRSZ &&
    837 	    (IN6_IS_ADDR_LINKLOCAL((const struct in6_addr *)addr) ||
    838 	     IN6_IS_ADDR_SITELOCAL((const struct in6_addr *)addr))) {
    839 		h_errno = HOST_NOT_FOUND;
    840 		return NULL;
    841 	}
    842 	if (af == AF_INET6 && len == NS_IN6ADDRSZ &&
    843 	    (IN6_IS_ADDR_V4MAPPED((const struct in6_addr *)addr) ||
    844 	     IN6_IS_ADDR_V4COMPAT((const struct in6_addr *)addr))) {
    845 		/* Unmap. */
    846 		uaddr += NS_IN6ADDRSZ - NS_INADDRSZ;
    847 		addr = uaddr;
    848 		af = AF_INET;
    849 		len = NS_INADDRSZ;
    850 	}
    851 	switch (af) {
    852 	case AF_INET:
    853 		size = NS_INADDRSZ;
    854 		break;
    855 	case AF_INET6:
    856 		size = NS_IN6ADDRSZ;
    857 		break;
    858 	default:
    859 		errno = EAFNOSUPPORT;
    860 		h_errno = NETDB_INTERNAL;
    861 		return NULL;
    862 	}
    863 	if (size != len) {
    864 		errno = EINVAL;
    865 		h_errno = NETDB_INTERNAL;
    866 		return NULL;
    867 	}
    868 	hp = NULL;
    869 	h_errno = NETDB_INTERNAL;
    870 	if (nsdispatch(&hp, dtab, NSDB_HOSTS, "gethostbyaddr",
    871 		default_dns_files, uaddr, len, af, netid, mark) != NS_SUCCESS)
    872 		return NULL;
    873 	h_errno = NETDB_SUCCESS;
    874 	return hp;
    875 }
    876 
    877 struct hostent *
    878 android_gethostbyaddrfornet(const void *addr, socklen_t len, int af, unsigned netid, unsigned mark)
    879 {
    880 	const char *cache_mode = getenv("ANDROID_DNS_MODE");
    881 
    882 	if (cache_mode == NULL || strcmp(cache_mode, "local") != 0) {
    883 		return android_gethostbyaddrfornet_proxy(addr, len, af, netid);
    884 	} else {
    885 		return android_gethostbyaddrfornet_real(addr,len, af, netid, mark);
    886 	}
    887 }
    888 
    889 struct hostent *
    890 gethostbyaddr(const void *addr, socklen_t len, int af)
    891 {
    892 	return android_gethostbyaddrfornet(addr, len, af, NETID_UNSET, MARK_UNSET);
    893 }
    894 
    895 
    896 static void
    897 _sethtent(int f)
    898 {
    899     res_static  rs = __res_get_static();
    900     if (rs == NULL) return;
    901 	if (!rs->hostf)
    902 		rs->hostf = fopen(_PATH_HOSTS, "r" );
    903 	else
    904 		rewind(rs->hostf);
    905 	rs->stayopen = f;
    906 }
    907 
    908 static void
    909 _endhtent(void)
    910 {
    911     res_static  rs = __res_get_static();
    912     if (rs == NULL) return;
    913 
    914 	if (rs->hostf && !rs->stayopen) {
    915 		(void) fclose(rs->hostf);
    916 		rs->hostf = NULL;
    917 	}
    918 }
    919 
    920 static struct hostent *
    921 _gethtent(void)
    922 {
    923 	char *p;
    924 	char *cp, **q;
    925 	int af, len;
    926 	res_static  rs = __res_get_static();
    927 
    928 	if (!rs->hostf && !(rs->hostf = fopen(_PATH_HOSTS, "r" ))) {
    929 		h_errno = NETDB_INTERNAL;
    930 		return NULL;
    931 	}
    932  again:
    933 	if (!(p = fgets(rs->hostbuf, sizeof rs->hostbuf, rs->hostf))) {
    934 		h_errno = HOST_NOT_FOUND;
    935 		return NULL;
    936 	}
    937 	if (*p == '#')
    938 		goto again;
    939 	if (!(cp = strpbrk(p, "#\n")))
    940 		goto again;
    941 	*cp = '\0';
    942 	if (!(cp = strpbrk(p, " \t")))
    943 		goto again;
    944 	*cp++ = '\0';
    945 	if (inet_pton(AF_INET6, p, (char *)(void *)rs->host_addr) > 0) {
    946 		af = AF_INET6;
    947 		len = IN6ADDRSZ;
    948 	} else if (inet_pton(AF_INET, p, (char *)(void *)rs->host_addr) > 0) {
    949 		res_state res = __res_get_state();
    950 		if (res == NULL)
    951 			return NULL;
    952 		if (res->options & RES_USE_INET6) {
    953 			map_v4v6_address((char *)(void *)rs->host_addr,
    954 			    (char *)(void *)rs->host_addr);
    955 			af = AF_INET6;
    956 			len = IN6ADDRSZ;
    957 		} else {
    958 			af = AF_INET;
    959 			len = INADDRSZ;
    960 		}
    961 		__res_put_state(res);
    962 	} else {
    963 		goto again;
    964 	}
    965 	/* if this is not something we're looking for, skip it. */
    966 	if (rs->host.h_addrtype != 0 && rs->host.h_addrtype != af)
    967 		goto again;
    968 	if (rs->host.h_length != 0 && rs->host.h_length != len)
    969 		goto again;
    970 	rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
    971 	rs->h_addr_ptrs[1] = NULL;
    972 	rs->host.h_addr_list = rs->h_addr_ptrs;
    973 	rs->host.h_length = len;
    974 	rs->host.h_addrtype = af;
    975 	while (*cp == ' ' || *cp == '\t')
    976 		cp++;
    977 	rs->host.h_name = cp;
    978 	q = rs->host.h_aliases = rs->host_aliases;
    979 	if ((cp = strpbrk(cp, " \t")) != NULL)
    980 		*cp++ = '\0';
    981 	while (cp && *cp) {
    982 		if (*cp == ' ' || *cp == '\t') {
    983 			cp++;
    984 			continue;
    985 		}
    986 		if (q < &rs->host_aliases[MAXALIASES - 1])
    987 			*q++ = cp;
    988 		if ((cp = strpbrk(cp, " \t")) != NULL)
    989 			*cp++ = '\0';
    990 	}
    991 	*q = NULL;
    992 	h_errno = NETDB_SUCCESS;
    993 	return &rs->host;
    994 }
    995 
    996 /*ARGSUSED*/
    997 int
    998 _gethtbyname(void *rv, void *cb_data, va_list ap)
    999 {
   1000 	struct hostent *hp;
   1001 	const char *name;
   1002 	int af;
   1003 
   1004 	assert(rv != NULL);
   1005 
   1006 	name = va_arg(ap, char *);
   1007 	/* NOSTRICT skip len */(void)va_arg(ap, int);
   1008 	af = va_arg(ap, int);
   1009 
   1010 	hp = NULL;
   1011 #if 0
   1012 	{
   1013 		res_state res = __res_get_state();
   1014 		if (res == NULL)
   1015 			return NS_NOTFOUND;
   1016 		if (res->options & RES_USE_INET6)
   1017 			hp = _gethtbyname2(name, AF_INET6);
   1018 		if (hp==NULL)
   1019 			hp = _gethtbyname2(name, AF_INET);
   1020 		__res_put_state(res);
   1021 	}
   1022 #else
   1023 	hp = _gethtbyname2(name, af);
   1024 #endif
   1025 	*((struct hostent **)rv) = hp;
   1026 	if (hp == NULL) {
   1027 		h_errno = HOST_NOT_FOUND;
   1028 		return NS_NOTFOUND;
   1029 	}
   1030 	return NS_SUCCESS;
   1031 }
   1032 
   1033 static struct hostent *
   1034 _gethtbyname2(const char *name, int af)
   1035 {
   1036 	struct hostent *p;
   1037 	char *tmpbuf, *ptr, **cp;
   1038 	int num;
   1039 	size_t len;
   1040 	res_static rs = __res_get_static();
   1041 
   1042 	assert(name != NULL);
   1043 
   1044 	_sethtent(rs->stayopen);
   1045 	ptr = tmpbuf = NULL;
   1046 	num = 0;
   1047 	while ((p = _gethtent()) != NULL && num < MAXADDRS) {
   1048 		if (p->h_addrtype != af)
   1049 			continue;
   1050 		if (strcasecmp(p->h_name, name) != 0) {
   1051 			for (cp = p->h_aliases; *cp != NULL; cp++)
   1052 				if (strcasecmp(*cp, name) == 0)
   1053 					break;
   1054 			if (*cp == NULL) continue;
   1055 		}
   1056 
   1057 		if (num == 0) {
   1058 			size_t bufsize;
   1059 			char *src;
   1060 
   1061 			bufsize = strlen(p->h_name) + 2 +
   1062 				  MAXADDRS * p->h_length +
   1063 				  ALIGNBYTES;
   1064 			for (cp = p->h_aliases; *cp != NULL; cp++)
   1065 				bufsize += strlen(*cp) + 1;
   1066 
   1067 			if ((tmpbuf = malloc(bufsize)) == NULL) {
   1068 				h_errno = NETDB_INTERNAL;
   1069 				return NULL;
   1070 			}
   1071 
   1072 			ptr = tmpbuf;
   1073 			src = p->h_name;
   1074 			while ((*ptr++ = *src++) != '\0');
   1075 			for (cp = p->h_aliases; *cp != NULL; cp++) {
   1076 				src = *cp;
   1077 				while ((*ptr++ = *src++) != '\0');
   1078 			}
   1079 			*ptr++ = '\0';
   1080 
   1081 			ptr = (char *)(void *)ALIGN(ptr);
   1082 		}
   1083 
   1084 		(void)memcpy(ptr, p->h_addr_list[0], (size_t)p->h_length);
   1085 		ptr += p->h_length;
   1086 		num++;
   1087 	}
   1088 	_endhtent();
   1089 	if (num == 0) return NULL;
   1090 
   1091 	len = ptr - tmpbuf;
   1092 	if (len > (sizeof(rs->hostbuf) - ALIGNBYTES)) {
   1093 		free(tmpbuf);
   1094 		errno = ENOSPC;
   1095 		h_errno = NETDB_INTERNAL;
   1096 		return NULL;
   1097 	}
   1098 	ptr = memcpy((void *)ALIGN(rs->hostbuf), tmpbuf, len);
   1099 	free(tmpbuf);
   1100 
   1101 	rs->host.h_name = ptr;
   1102 	while (*ptr++);
   1103 
   1104 	cp = rs->host_aliases;
   1105 	while (*ptr) {
   1106 		*cp++ = ptr;
   1107 		while (*ptr++);
   1108 	}
   1109 	ptr++;
   1110 	*cp = NULL;
   1111 
   1112 	ptr = (char *)(void *)ALIGN(ptr);
   1113 	cp = rs->h_addr_ptrs;
   1114 	while (num--) {
   1115 		*cp++ = ptr;
   1116 		ptr += rs->host.h_length;
   1117 	}
   1118 	*cp = NULL;
   1119 
   1120 	return &rs->host;
   1121 }
   1122 
   1123 /*ARGSUSED*/
   1124 static int
   1125 _gethtbyaddr(void *rv, void *cb_data, va_list ap)
   1126 {
   1127 	struct hostent *p;
   1128 	const unsigned char *addr;
   1129 	int len, af;
   1130 	res_static  rs = __res_get_static();
   1131 
   1132 	assert(rv != NULL);
   1133 
   1134 	addr = va_arg(ap, unsigned char *);
   1135 	len = va_arg(ap, int);
   1136 	af = va_arg(ap, int);
   1137 
   1138 	rs->host.h_length = len;
   1139 	rs->host.h_addrtype = af;
   1140 
   1141 	_sethtent(rs->stayopen);
   1142 	while ((p = _gethtent()) != NULL)
   1143 		if (p->h_addrtype == af && !memcmp(p->h_addr, addr,
   1144 		    (size_t)len))
   1145 			break;
   1146 	_endhtent();
   1147 	*((struct hostent **)rv) = p;
   1148 	if (p==NULL) {
   1149 		h_errno = HOST_NOT_FOUND;
   1150 		return NS_NOTFOUND;
   1151 	}
   1152 	return NS_SUCCESS;
   1153 }
   1154 
   1155 static void
   1156 map_v4v6_address(const char *src, char *dst)
   1157 {
   1158 	u_char *p = (u_char *)dst;
   1159 	char tmp[INADDRSZ];
   1160 	int i;
   1161 
   1162 	assert(src != NULL);
   1163 	assert(dst != NULL);
   1164 
   1165 	/* Stash a temporary copy so our caller can update in place. */
   1166 	(void)memcpy(tmp, src, INADDRSZ);
   1167 	/* Mark this ipv6 addr as a mapped ipv4. */
   1168 	for (i = 0; i < 10; i++)
   1169 		*p++ = 0x00;
   1170 	*p++ = 0xff;
   1171 	*p++ = 0xff;
   1172 	/* Retrieve the saved copy and we're done. */
   1173 	(void)memcpy((void *)p, tmp, INADDRSZ);
   1174 }
   1175 
   1176 static void
   1177 map_v4v6_hostent(struct hostent *hp, char **bpp, char *ep)
   1178 {
   1179 	char **ap;
   1180 
   1181 	assert(hp != NULL);
   1182 	assert(bpp != NULL);
   1183 	assert(ep != NULL);
   1184 
   1185 	if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
   1186 		return;
   1187 	hp->h_addrtype = AF_INET6;
   1188 	hp->h_length = IN6ADDRSZ;
   1189 	for (ap = hp->h_addr_list; *ap; ap++) {
   1190 		int i = sizeof(align) - (size_t)((u_long)*bpp % sizeof(align));
   1191 
   1192 		if (ep - *bpp < (i + IN6ADDRSZ)) {
   1193 			/* Out of memory.  Truncate address list here.  XXX */
   1194 			*ap = NULL;
   1195 			return;
   1196 		}
   1197 		*bpp += i;
   1198 		map_v4v6_address(*ap, *bpp);
   1199 		*ap = *bpp;
   1200 		*bpp += IN6ADDRSZ;
   1201 	}
   1202 }
   1203 
   1204 static void
   1205 addrsort(char **ap, int num, res_state res)
   1206 {
   1207 	int i, j;
   1208 	char **p;
   1209 	short aval[MAXADDRS];
   1210 	int needsort = 0;
   1211 
   1212 	assert(ap != NULL);
   1213 
   1214 	p = ap;
   1215 	for (i = 0; i < num; i++, p++) {
   1216 	    for (j = 0 ; (unsigned)j < res->nsort; j++)
   1217 		if (res->sort_list[j].addr.s_addr ==
   1218 		    (((struct in_addr *)(void *)(*p))->s_addr &
   1219 		    res->sort_list[j].mask))
   1220 			break;
   1221 	    aval[i] = j;
   1222 	    if (needsort == 0 && i > 0 && j < aval[i-1])
   1223 		needsort = i;
   1224 	}
   1225 	if (!needsort)
   1226 	    return;
   1227 
   1228 	while (needsort < num) {
   1229 	    for (j = needsort - 1; j >= 0; j--) {
   1230 		if (aval[j] > aval[j+1]) {
   1231 		    char *hp;
   1232 
   1233 		    i = aval[j];
   1234 		    aval[j] = aval[j+1];
   1235 		    aval[j+1] = i;
   1236 
   1237 		    hp = ap[j];
   1238 		    ap[j] = ap[j+1];
   1239 		    ap[j+1] = hp;
   1240 		} else
   1241 		    break;
   1242 	    }
   1243 	    needsort++;
   1244 	}
   1245 }
   1246 
   1247 struct hostent *
   1248 gethostent(void)
   1249 {
   1250     res_static  rs = __res_get_static();
   1251 	rs->host.h_addrtype = 0;
   1252 	rs->host.h_length = 0;
   1253 	return _gethtent();
   1254 }
   1255 
   1256 /*ARGSUSED*/
   1257 static int
   1258 _dns_gethtbyname(void *rv, void *cb_data, va_list ap)
   1259 {
   1260 	querybuf *buf;
   1261 	int n, type;
   1262 	struct hostent *hp;
   1263 	const char *name;
   1264 	int af;
   1265 	res_state res;
   1266 
   1267 	assert(rv != NULL);
   1268 
   1269 	name = va_arg(ap, char *);
   1270 	/* NOSTRICT skip len */(void)va_arg(ap, int);
   1271 	af = va_arg(ap, int);
   1272 
   1273 	switch (af) {
   1274 	case AF_INET:
   1275 		type = T_A;
   1276 		break;
   1277 	case AF_INET6:
   1278 		type = T_AAAA;
   1279 		break;
   1280 	default:
   1281 		return NS_UNAVAIL;
   1282 	}
   1283 	buf = malloc(sizeof(*buf));
   1284 	if (buf == NULL) {
   1285 		h_errno = NETDB_INTERNAL;
   1286 		return NS_NOTFOUND;
   1287 	}
   1288 	res = __res_get_state();
   1289 	if (res == NULL) {
   1290 		free(buf);
   1291 		return NS_NOTFOUND;
   1292 	}
   1293 	n = res_nsearch(res, name, C_IN, type, buf->buf, sizeof(buf->buf));
   1294 	if (n < 0) {
   1295 		free(buf);
   1296 		dprintf("res_nsearch failed (%d)\n", res, n);
   1297 		__res_put_state(res);
   1298 		return NS_NOTFOUND;
   1299 	}
   1300 	hp = getanswer(buf, n, name, type, res);
   1301 	free(buf);
   1302 	__res_put_state(res);
   1303 	if (hp == NULL)
   1304 		switch (h_errno) {
   1305 		case HOST_NOT_FOUND:
   1306 			return NS_NOTFOUND;
   1307 		case TRY_AGAIN:
   1308 			return NS_TRYAGAIN;
   1309 		default:
   1310 			return NS_UNAVAIL;
   1311 		}
   1312 	*((struct hostent **)rv) = hp;
   1313 	return NS_SUCCESS;
   1314 }
   1315 
   1316 /*ARGSUSED*/
   1317 static int
   1318 _dns_gethtbyaddr(void *rv, void	*cb_data, va_list ap)
   1319 {
   1320 	char qbuf[MAXDNAME + 1], *qp, *ep;
   1321 	int n;
   1322 	querybuf *buf;
   1323 	struct hostent *hp;
   1324 	const unsigned char *uaddr;
   1325 	int len, af, advance;
   1326 	res_state res;
   1327 	unsigned netid, mark;
   1328 	res_static rs = __res_get_static();
   1329 
   1330 	assert(rv != NULL);
   1331 
   1332 	uaddr = va_arg(ap, unsigned char *);
   1333 	len = va_arg(ap, int);
   1334 	af = va_arg(ap, int);
   1335 	netid = va_arg(ap, unsigned);
   1336 	mark = va_arg(ap, unsigned);
   1337 
   1338 	switch (af) {
   1339 	case AF_INET:
   1340 		(void)snprintf(qbuf, sizeof(qbuf), "%u.%u.%u.%u.in-addr.arpa",
   1341 		    (uaddr[3] & 0xff), (uaddr[2] & 0xff),
   1342 		    (uaddr[1] & 0xff), (uaddr[0] & 0xff));
   1343 		break;
   1344 
   1345 	case AF_INET6:
   1346 		qp = qbuf;
   1347 		ep = qbuf + sizeof(qbuf) - 1;
   1348 		for (n = IN6ADDRSZ - 1; n >= 0; n--) {
   1349 			advance = snprintf(qp, (size_t)(ep - qp), "%x.%x.",
   1350 			    uaddr[n] & 0xf,
   1351 			    ((unsigned int)uaddr[n] >> 4) & 0xf);
   1352 			if (advance > 0 && qp + advance < ep)
   1353 				qp += advance;
   1354 			else {
   1355 				h_errno = NETDB_INTERNAL;
   1356 				return NS_NOTFOUND;
   1357 			}
   1358 		}
   1359 		if (strlcat(qbuf, "ip6.arpa", sizeof(qbuf)) >= sizeof(qbuf)) {
   1360 			h_errno = NETDB_INTERNAL;
   1361 			return NS_NOTFOUND;
   1362 		}
   1363 		break;
   1364 	default:
   1365 		abort();
   1366 	}
   1367 
   1368 	buf = malloc(sizeof(*buf));
   1369 	if (buf == NULL) {
   1370 		h_errno = NETDB_INTERNAL;
   1371 		return NS_NOTFOUND;
   1372 	}
   1373 	res = __res_get_state();
   1374 	if (res == NULL) {
   1375 		free(buf);
   1376 		return NS_NOTFOUND;
   1377 	}
   1378 	res_setnetid(res, netid);
   1379 	res_setmark(res, mark);
   1380 	n = res_nquery(res, qbuf, C_IN, T_PTR, buf->buf, sizeof(buf->buf));
   1381 	if (n < 0) {
   1382 		free(buf);
   1383 		dprintf("res_nquery failed (%d)\n", res, n);
   1384 		__res_put_state(res);
   1385 		return NS_NOTFOUND;
   1386 	}
   1387 	hp = getanswer(buf, n, qbuf, T_PTR, res);
   1388 	free(buf);
   1389 	if (hp == NULL) {
   1390 		__res_put_state(res);
   1391 		switch (h_errno) {
   1392 		case HOST_NOT_FOUND:
   1393 			return NS_NOTFOUND;
   1394 		case TRY_AGAIN:
   1395 			return NS_TRYAGAIN;
   1396 		default:
   1397 			return NS_UNAVAIL;
   1398 		}
   1399 	}
   1400 	hp->h_addrtype = af;
   1401 	hp->h_length = len;
   1402 	(void)memcpy(rs->host_addr, uaddr, (size_t)len);
   1403 	rs->h_addr_ptrs[0] = (char *)(void *)rs->host_addr;
   1404 	rs->h_addr_ptrs[1] = NULL;
   1405 	if (af == AF_INET && (res->options & RES_USE_INET6)) {
   1406 		map_v4v6_address((char *)(void *)rs->host_addr,
   1407 		    (char *)(void *)rs->host_addr);
   1408 		hp->h_addrtype = AF_INET6;
   1409 		hp->h_length = IN6ADDRSZ;
   1410 	}
   1411 
   1412 	__res_put_state(res);
   1413 	*((struct hostent **)rv) = hp;
   1414 	h_errno = NETDB_SUCCESS;
   1415 	return NS_SUCCESS;
   1416 }
   1417