The Tor Browser / file revision

 /*	$NetBSD: res_send.c,v 1.9 2006/01/24 17:41:25 christos Exp $	*/

 /*

  * Copyright 2008  Android Open Source Project (source port randomization)

  * Copyright (c) 1985, 1989, 1993

  *    The Regents of the University of California.  All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met:

  * 1. Redistributions of source code must retain the above copyright

  *    notice, this list of conditions and the following disclaimer.

  * 2. Redistributions in binary form must reproduce the above copyright

  *    notice, this list of conditions and the following disclaimer in the

  *    documentation and/or other materials provided with the distribution.

  * 3. All advertising materials mentioning features or use of this software

  *    must display the following acknowledgement:

  * 	This product includes software developed by the University of

  * 	California, Berkeley and its contributors.

  * 4. Neither the name of the University nor the names of its contributors

  *    may be used to endorse or promote products derived from this software

  *    without specific prior written permission.

  *

  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND

  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE

  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

  * SUCH DAMAGE.

  */

 /*

  * Portions Copyright (c) 1993 by Digital Equipment Corporation.

  *

  * Permission to use, copy, modify, and distribute this software for any

  * purpose with or without fee is hereby granted, provided that the above

  * copyright notice and this permission notice appear in all copies, and that

  * the name of Digital Equipment Corporation not be used in advertising or

  * publicity pertaining to distribution of the document or software without

  * specific, written prior permission.

  *

  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL

  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES

  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT

  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL

  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR

  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS

  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS

  * SOFTWARE.

  */

 /*

  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")

  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.

  *

  * Permission to use, copy, modify, and distribute this software for any

  * purpose with or without fee is hereby granted, provided that the above

  * copyright notice and this permission notice appear in all copies.

  *

  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES

  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR

  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT

  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

  */

 /*

  * This version of this file is derived from Android 2.3 "Gingerbread",

  * which contains uncredited changes by Android/Google developers.  It has

  * been modified in 2011 for use in the Android build of Mozilla Firefox by

  * Mozilla contributors (including Michael Edwards <m.k.edwards@gmail.com>,

  * and Steve Workman <sjhworkman@gmail.com>).

  * These changes are offered under the same license as the original NetBSD

  * file, whose copyright and license are unchanged above.

  */

 #define ANDROID_CHANGES 1

 #define MOZILLA_NECKO_EXCLUDE_CODE 1 

 #include <sys/cdefs.h>

 #if defined(LIBC_SCCS) && !defined(lint)

 #ifdef notdef

 static const char sccsid[] = "@(#)res_send.c	8.1 (Berkeley) 6/4/93";

 static const char rcsid[] = "Id: res_send.c,v 1.5.2.2.4.5 2004/08/10 02:19:56 marka Exp";

 #else

 __RCSID("$NetBSD: res_send.c,v 1.9 2006/01/24 17:41:25 christos Exp $");

 #endif

 #endif /* LIBC_SCCS and not lint */

 /* Set to 0 to not use the small/simple/limited DNS cache

  * Cache implemented higher up in Gecko */

 #define  USE_RESOLV_CACHE  0

 /*

  * Send query to name server and wait for reply.

  */

 #include <sys/types.h>

 #include <sys/param.h>

 #include <sys/time.h>

 #include <sys/socket.h>

 #include <sys/uio.h>

 #include <netinet/in.h>

 #include "arpa_nameser.h"

 #include <arpa/inet.h>

 #include <errno.h>

 #include <netdb.h>

 #ifdef ANDROID_CHANGES

 #include "resolv_private.h"

 #else

 #include <resolv.h>

 #endif

 #include <signal.h>

 #include <stdio.h>

 #include <stdlib.h>

 #include <string.h>

 #include <unistd.h>

 #include "eventlib.h"

 #if USE_RESOLV_CACHE

 #  include <resolv_cache.h>

 #endif

 #ifndef DE_CONST

 #define DE_CONST(c,v)   v = ((c) ? \

     strchr((const void *)(c), *(const char *)(const void *)(c)) : NULL)

 #endif

 /* Options.  Leave them on. */

 #ifndef DEBUG

 #define DEBUG

 #endif

 #include "res_debug.h"

 #include "res_private.h"

 #define EXT(res) ((res)->_u._ext)

 static const int highestFD = FD_SETSIZE - 1;

 /* Forward. */

 static int		get_salen __P((const struct sockaddr *));

 static struct sockaddr * get_nsaddr __P((res_state, size_t));

 static int		send_vc(res_state, const u_char *, int,

 				u_char *, int, int *, int);

 static int		send_dg(res_state, const u_char *, int,

 				u_char *, int, int *, int,

 				int *, int *);

 static void		Aerror(const res_state, FILE *, const char *, int,

 			       const struct sockaddr *, int);

 static void		Perror(const res_state, FILE *, const char *, int);

 static int		sock_eq(struct sockaddr *, struct sockaddr *);

 #ifdef NEED_PSELECT

 static int		pselect(int, void *, void *, void *,

 				struct timespec *,

 				const sigset_t *);

 #endif

 void res_pquery(const res_state, const u_char *, int, FILE *);

 /* BIONIC-BEGIN: implement source port randomization */

 typedef union {

     struct sockaddr      sa;

     struct sockaddr_in   sin;

     struct sockaddr_in6  sin6;

 } _sockaddr_union;

 static int

 random_bind( int  s, int  family )

 {

     _sockaddr_union  u;

     int              j;

     socklen_t        slen;

     /* clear all, this also sets the IP4/6 address to 'any' */

     memset( &u, 0, sizeof u );

     switch (family) {

         case AF_INET:

             u.sin.sin_family = family;

             slen             = sizeof u.sin;

             break;

         case AF_INET6:

             u.sin6.sin6_family = family;

             slen               = sizeof u.sin6;

             break;

         default:

             errno = EPROTO;

             return -1;

     }

     /* first try to bind to a random source port a few times */

     for (j = 0; j < 10; j++) {

         /* find a random port between 1025 .. 65534 */

         int  port = 1025 + (res_randomid() % (65535-1025));

         if (family == AF_INET)

             u.sin.sin_port = htons(port);

         else

             u.sin6.sin6_port = htons(port);

         if ( !bind( s, &u.sa, slen ) )

             return 0;

     }

     /* nothing after 10 tries, our network table is probably busy */

     /* let the system decide which port is best */

     if (family == AF_INET)

         u.sin.sin_port = 0;

     else

         u.sin6.sin6_port = 0;

     return bind( s, &u.sa, slen );

 }

 /* BIONIC-END */

 static const int niflags = NI_NUMERICHOST | NI_NUMERICSERV;

 /* Public. */

 /* int

  * res_isourserver(ina)

  *	looks up "ina" in _res.ns_addr_list[]

  * returns:

  *	0  : not found

  *	>0 : found

  * author:

  *	paul vixie, 29may94

  */

 int

 res_ourserver_p(const res_state statp, const struct sockaddr *sa) {

 	const struct sockaddr_in *inp, *srv;

 	const struct sockaddr_in6 *in6p, *srv6;

 	int ns;

 	switch (sa->sa_family) {

 	case AF_INET:

 		inp = (const struct sockaddr_in *)(const void *)sa;

 		for (ns = 0;  ns < statp->nscount;  ns++) {

 			srv = (struct sockaddr_in *)(void *)get_nsaddr(statp, (size_t)ns);

 			if (srv->sin_family == inp->sin_family &&

 			    srv->sin_port == inp->sin_port &&

 			    (srv->sin_addr.s_addr == INADDR_ANY ||

 			     srv->sin_addr.s_addr == inp->sin_addr.s_addr))

 				return (1);

 		}

 		break;

 	case AF_INET6:

 		if (EXT(statp).ext == NULL)

 			break;

 		in6p = (const struct sockaddr_in6 *)(const void *)sa;

 		for (ns = 0;  ns < statp->nscount;  ns++) {

 			srv6 = (struct sockaddr_in6 *)(void *)get_nsaddr(statp, (size_t)ns);

 			if (srv6->sin6_family == in6p->sin6_family &&

 			    srv6->sin6_port == in6p->sin6_port &&

 #ifdef HAVE_SIN6_SCOPE_ID

 			    (srv6->sin6_scope_id == 0 ||

 			     srv6->sin6_scope_id == in6p->sin6_scope_id) &&

 #endif

 			    (IN6_IS_ADDR_UNSPECIFIED(&srv6->sin6_addr) ||

 			     IN6_ARE_ADDR_EQUAL(&srv6->sin6_addr, &in6p->sin6_addr)))

 				return (1);

 		}

 		break;

 	default:

 		break;

 	}

 	return (0);

 }

 /* int

  * res_nameinquery(name, type, class, buf, eom)

  *	look for (name,type,class) in the query section of packet (buf,eom)

  * requires:

  *	buf + HFIXEDSZ <= eom

  * returns:

  *	-1 : format error

  *	0  : not found

  *	>0 : found

  * author:

  *	paul vixie, 29may94

  */

 int

 res_nameinquery(const char *name, int type, int class,

 		const u_char *buf, const u_char *eom)

 {

 	const u_char *cp = buf + HFIXEDSZ;

 	int qdcount = ntohs(((const HEADER*)(const void *)buf)->qdcount);

 	while (qdcount-- > 0) {

 		char tname[MAXDNAME+1];

 		int n, ttype, tclass;

 		n = dn_expand(buf, eom, cp, tname, sizeof tname);

 		if (n < 0)

 			return (-1);

 		cp += n;

 		if (cp + 2 * INT16SZ > eom)

 			return (-1);

 		ttype = ns_get16(cp); cp += INT16SZ;

 		tclass = ns_get16(cp); cp += INT16SZ;

 		if (ttype == type && tclass == class &&

 		    ns_samename(tname, name) == 1)

 			return (1);

 	}

 	return (0);

 }

 /* int

  * res_queriesmatch(buf1, eom1, buf2, eom2)

  *	is there a 1:1 mapping of (name,type,class)

  *	in (buf1,eom1) and (buf2,eom2)?

  * returns:

  *	-1 : format error

  *	0  : not a 1:1 mapping

  *	>0 : is a 1:1 mapping

  * author:

  *	paul vixie, 29may94

  */

 int

 res_queriesmatch(const u_char *buf1, const u_char *eom1,

 		 const u_char *buf2, const u_char *eom2)

 {

 	const u_char *cp = buf1 + HFIXEDSZ;

 	int qdcount = ntohs(((const HEADER*)(const void *)buf1)->qdcount);

 	if (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2)

 		return (-1);

 	/*

 	 * Only header section present in replies to

 	 * dynamic update packets.

 	 */

 	if ((((const HEADER *)(const void *)buf1)->opcode == ns_o_update) &&

 	    (((const HEADER *)(const void *)buf2)->opcode == ns_o_update))

 		return (1);

 	if (qdcount != ntohs(((const HEADER*)(const void *)buf2)->qdcount))

 		return (0);

 	while (qdcount-- > 0) {

 		char tname[MAXDNAME+1];

 		int n, ttype, tclass;

 		n = dn_expand(buf1, eom1, cp, tname, sizeof tname);

 		if (n < 0)

 			return (-1);

 		cp += n;

 		if (cp + 2 * INT16SZ > eom1)

 			return (-1);

 		ttype = ns_get16(cp);	cp += INT16SZ;

 		tclass = ns_get16(cp); cp += INT16SZ;

 		if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))

 			return (0);

 	}

 	return (1);

 }

 int

 res_nsend(res_state statp,

 	  const u_char *buf, int buflen, u_char *ans, int anssiz)

 {

 	int gotsomewhere, terrno, try, v_circuit, resplen, ns, n;

 	char abuf[NI_MAXHOST];

 #if USE_RESOLV_CACHE

         struct resolv_cache*  cache;

         ResolvCacheStatus     cache_status = RESOLV_CACHE_UNSUPPORTED;

 #endif

 	if (statp->nscount == 0) {

 		errno = ESRCH;

 		return (-1);

 	}

 	if (anssiz < HFIXEDSZ) {

 		errno = EINVAL;

 		return (-1);

 	}

 	DprintQ((statp->options & RES_DEBUG) || (statp->pfcode & RES_PRF_QUERY),

 		(stdout, ";; res_send()\n"), buf, buflen);

 	v_circuit = (statp->options & RES_USEVC) || buflen > PACKETSZ;

 	gotsomewhere = 0;

 	terrno = ETIMEDOUT;

 #if USE_RESOLV_CACHE

         cache = __get_res_cache();

         if (cache != NULL) {

             int  anslen = 0;

             cache_status = _resolv_cache_lookup(

                                 cache, buf, buflen,

                                 ans, anssiz, &anslen);

             if (cache_status == RESOLV_CACHE_FOUND) {

                 return anslen;

             }

         }

 #endif

 	/*

 	 * If the ns_addr_list in the resolver context has changed, then

 	 * invalidate our cached copy and the associated timing data.

 	 */

 	if (EXT(statp).nscount != 0) {

 		int needclose = 0;

 		struct sockaddr_storage peer;

 		socklen_t peerlen;

 		if (EXT(statp).nscount != statp->nscount)

 			needclose++;

 		else

 			for (ns = 0; ns < statp->nscount; ns++) {

 				if (statp->nsaddr_list[ns].sin_family &&

 				    !sock_eq((struct sockaddr *)(void *)&statp->nsaddr_list[ns],

 					     (struct sockaddr *)(void *)&EXT(statp).ext->nsaddrs[ns])) {

 					needclose++;

 					break;

 				}

 				if (EXT(statp).nssocks[ns] == -1)

 					continue;

 				peerlen = sizeof(peer);

 				if (getsockname(EXT(statp).nssocks[ns],

 				    (struct sockaddr *)(void *)&peer, &peerlen) < 0) {

 					needclose++;

 					break;

 				}

 				if (!sock_eq((struct sockaddr *)(void *)&peer,

 				    get_nsaddr(statp, (size_t)ns))) {

 					needclose++;

 					break;

 				}

 			}

 		if (needclose) {

 			res_nclose(statp);

 			EXT(statp).nscount = 0;

 		}

 	}

 	/*

 	 * Maybe initialize our private copy of the ns_addr_list.

 	 */

 	if (EXT(statp).nscount == 0) {

 		for (ns = 0; ns < statp->nscount; ns++) {

 			EXT(statp).nstimes[ns] = RES_MAXTIME;

 			EXT(statp).nssocks[ns] = -1;

 			if (!statp->nsaddr_list[ns].sin_family)

 				continue;

 			EXT(statp).ext->nsaddrs[ns].sin =

 				 statp->nsaddr_list[ns];

 		}

 		EXT(statp).nscount = statp->nscount;

 	}

 	/*

 	 * Some resolvers want to even out the load on their nameservers.

 	 * Note that RES_BLAST overrides RES_ROTATE.

 	 */

 	if ((statp->options & RES_ROTATE) != 0U &&

 	    (statp->options & RES_BLAST) == 0U) {

 		union res_sockaddr_union inu;

 		struct sockaddr_in ina;

 		int lastns = statp->nscount - 1;

 		int fd;

 		u_int16_t nstime;

 		if (EXT(statp).ext != NULL)

 			inu = EXT(statp).ext->nsaddrs[0];

 		ina = statp->nsaddr_list[0];

 		fd = EXT(statp).nssocks[0];

 		nstime = EXT(statp).nstimes[0];

 		for (ns = 0; ns < lastns; ns++) {

 			if (EXT(statp).ext != NULL)

                                 EXT(statp).ext->nsaddrs[ns] =

 					EXT(statp).ext->nsaddrs[ns + 1];

 			statp->nsaddr_list[ns] = statp->nsaddr_list[ns + 1];

 			EXT(statp).nssocks[ns] = EXT(statp).nssocks[ns + 1];

 			EXT(statp).nstimes[ns] = EXT(statp).nstimes[ns + 1];

 		}

 		if (EXT(statp).ext != NULL)

 			EXT(statp).ext->nsaddrs[lastns] = inu;

 		statp->nsaddr_list[lastns] = ina;

 		EXT(statp).nssocks[lastns] = fd;

 		EXT(statp).nstimes[lastns] = nstime;

 	}

 	/*

 	 * Send request, RETRY times, or until successful.

 	 */

 	for (try = 0; try < statp->retry; try++) {

 	    for (ns = 0; ns < statp->nscount; ns++) {

 		struct sockaddr *nsap;

 		int nsaplen;

 		nsap = get_nsaddr(statp, (size_t)ns);

 		nsaplen = get_salen(nsap);

 		statp->_flags &= ~RES_F_LASTMASK;

 		statp->_flags |= (ns << RES_F_LASTSHIFT);

  same_ns:

 		if (statp->qhook) {

 			int done = 0, loops = 0;

 			do {

 				res_sendhookact act;

 				act = (*statp->qhook)(&nsap, &buf, &buflen,

 						      ans, anssiz, &resplen);

 				switch (act) {

 				case res_goahead:

 					done = 1;

 					break;

 				case res_nextns:

 					res_nclose(statp);

 					goto next_ns;

 				case res_done:

 					return (resplen);

 				case res_modified:

 					/* give the hook another try */

 					if (++loops < 42) /*doug adams*/

 						break;

 					/*FALLTHROUGH*/

 				case res_error:

 					/*FALLTHROUGH*/

 				default:

 					goto fail;

 				}

 			} while (!done);

 		}

 		Dprint(((statp->options & RES_DEBUG) &&

 			getnameinfo(nsap, (socklen_t)nsaplen, abuf, sizeof(abuf),

 				    NULL, 0, niflags) == 0),

 		       (stdout, ";; Querying server (# %d) address = %s\n",

 			ns + 1, abuf));

 		if (v_circuit) {

 			/* Use VC; at most one attempt per server. */

 			try = statp->retry;

 			n = send_vc(statp, buf, buflen, ans, anssiz, &terrno,

 				    ns);

 			if (n < 0)

 				goto fail;

 			if (n == 0)

 				goto next_ns;

 			resplen = n;

 		} else {

 			/* Use datagrams. */

 			n = send_dg(statp, buf, buflen, ans, anssiz, &terrno,

 				    ns, &v_circuit, &gotsomewhere);

 			if (n < 0)

 				goto fail;

 			if (n == 0)

 				goto next_ns;

 			if (v_circuit)

 				goto same_ns;

 			resplen = n;

 		}

 		Dprint((statp->options & RES_DEBUG) ||

 		       ((statp->pfcode & RES_PRF_REPLY) &&

 			(statp->pfcode & RES_PRF_HEAD1)),

 		       (stdout, ";; got answer:\n"));

 		DprintQ((statp->options & RES_DEBUG) ||

 			(statp->pfcode & RES_PRF_REPLY),

 			(stdout, "%s", ""),

 			ans, (resplen > anssiz) ? anssiz : resplen);

 #if USE_RESOLV_CACHE

                 if (cache_status == RESOLV_CACHE_NOTFOUND) {

                     _resolv_cache_add(cache, buf, buflen,

                                       ans, resplen);

                 }

 #endif

 		/*

 		 * If we have temporarily opened a virtual circuit,

 		 * or if we haven't been asked to keep a socket open,

 		 * close the socket.

 		 */

 		if ((v_circuit && (statp->options & RES_USEVC) == 0U) ||

 		    (statp->options & RES_STAYOPEN) == 0U) {

 			res_nclose(statp);

 		}

 		if (statp->rhook) {

 			int done = 0, loops = 0;

 			do {

 				res_sendhookact act;

 				act = (*statp->rhook)(nsap, buf, buflen,

 						      ans, anssiz, &resplen);

 				switch (act) {

 				case res_goahead:

 				case res_done:

 					done = 1;

 					break;

 				case res_nextns:

 					res_nclose(statp);

 					goto next_ns;

 				case res_modified:

 					/* give the hook another try */

 					if (++loops < 42) /*doug adams*/

 						break;

 					/*FALLTHROUGH*/

 				case res_error:

 					/*FALLTHROUGH*/

 				default:

 					goto fail;

 				}

 			} while (!done);

 		}

 		return (resplen);

  next_ns: ;

 	   } /*foreach ns*/

 	} /*foreach retry*/

 	res_nclose(statp);

 	if (!v_circuit) {

 		if (!gotsomewhere)

 			errno = ECONNREFUSED;	/* no nameservers found */

 		else

 			errno = ETIMEDOUT;	/* no answer obtained */

 	} else

 		errno = terrno;

 	return (-1);

  fail:

 	res_nclose(statp);

 	return (-1);

 }

 /* Private */

 static int

 get_salen(sa)

 	const struct sockaddr *sa;

 {

 #ifdef HAVE_SA_LEN

 	/* There are people do not set sa_len.  Be forgiving to them. */

 	if (sa->sa_len)

 		return (sa->sa_len);

 #endif

 	if (sa->sa_family == AF_INET)

 		return (sizeof(struct sockaddr_in));

 	else if (sa->sa_family == AF_INET6)

 		return (sizeof(struct sockaddr_in6));

 	else

 		return (0);	/* unknown, die on connect */

 }

 /*

  * pick appropriate nsaddr_list for use.  see res_init() for initialization.

  */

 static struct sockaddr *

 get_nsaddr(statp, n)

 	res_state statp;

 	size_t n;

 {

 	if (!statp->nsaddr_list[n].sin_family && EXT(statp).ext) {

 		/*

 		 * - EXT(statp).ext->nsaddrs[n] holds an address that is larger

 		 *   than struct sockaddr, and

 		 * - user code did not update statp->nsaddr_list[n].

 		 */

 		return (struct sockaddr *)(void *)&EXT(statp).ext->nsaddrs[n];

 	} else {

 		/*

 		 * - user code updated statp->nsaddr_list[n], or

 		 * - statp->nsaddr_list[n] has the same content as

 		 *   EXT(statp).ext->nsaddrs[n].

 		 */

 		return (struct sockaddr *)(void *)&statp->nsaddr_list[n];

 	}

 }

 static int

 send_vc(res_state statp,

 	const u_char *buf, int buflen, u_char *ans, int anssiz,

 	int *terrno, int ns)

 {

 	const HEADER *hp = (const HEADER *)(const void *)buf;

 	HEADER *anhp = (HEADER *)(void *)ans;

 	struct sockaddr *nsap;

 	int nsaplen;

 	int truncating, connreset, resplen, n;

 	struct iovec iov[2];

 	u_short len;

 	u_char *cp;

 	void *tmp;

 	nsap = get_nsaddr(statp, (size_t)ns);

 	nsaplen = get_salen(nsap);

 	connreset = 0;

  same_ns:

 	truncating = 0;

 	/* Are we still talking to whom we want to talk to? */

 	if (statp->_vcsock >= 0 && (statp->_flags & RES_F_VC) != 0) {

 		struct sockaddr_storage peer;

 		socklen_t size = sizeof peer;

 		if (getpeername(statp->_vcsock,

 				(struct sockaddr *)(void *)&peer, &size) < 0 ||

 		    !sock_eq((struct sockaddr *)(void *)&peer, nsap)) {

 			res_nclose(statp);

 			statp->_flags &= ~RES_F_VC;

 		}

 	}

 	if (statp->_vcsock < 0 || (statp->_flags & RES_F_VC) == 0) {

 		if (statp->_vcsock >= 0)

 			res_nclose(statp);

 		statp->_vcsock = socket(nsap->sa_family, SOCK_STREAM, 0);

 		if (statp->_vcsock > highestFD) {

 			res_nclose(statp);

 			errno = ENOTSOCK;

 		}

 		if (statp->_vcsock < 0) {

 			switch (errno) {

 			case EPROTONOSUPPORT:

 #ifdef EPFNOSUPPORT

 			case EPFNOSUPPORT:

 #endif

 			case EAFNOSUPPORT:

 				Perror(statp, stderr, "socket(vc)", errno);

 				return (0);

 			default:

 				*terrno = errno;

 				Perror(statp, stderr, "socket(vc)", errno);

 				return (-1);

 			}

 		}

 		errno = 0;

 		if (random_bind(statp->_vcsock,nsap->sa_family) < 0) {

 			*terrno = errno;

 			Aerror(statp, stderr, "bind/vc", errno, nsap,

 			    nsaplen);

 			res_nclose(statp);

 			return (0);

 		}

 		if (connect(statp->_vcsock, nsap, (socklen_t)nsaplen) < 0) {

 			*terrno = errno;

 			Aerror(statp, stderr, "connect/vc", errno, nsap,

 			    nsaplen);

 			res_nclose(statp);

 			return (0);

 		}

 		statp->_flags |= RES_F_VC;

 	}

 	/*

 	 * Send length & message

 	 */

 	ns_put16((u_short)buflen, (u_char*)(void *)&len);

 	iov[0] = evConsIovec(&len, INT16SZ);

 	DE_CONST(buf, tmp);

 	iov[1] = evConsIovec(tmp, (size_t)buflen);

 	if (writev(statp->_vcsock, iov, 2) != (INT16SZ + buflen)) {

 		*terrno = errno;

 		Perror(statp, stderr, "write failed", errno);

 		res_nclose(statp);

 		return (0);

 	}

 	/*

 	 * Receive length & response

 	 */

  read_len:

 	cp = ans;

 	len = INT16SZ;

 	while ((n = read(statp->_vcsock, (char *)cp, (size_t)len)) > 0) {

 		cp += n;

 		if ((len -= n) == 0)

 			break;

 	}

 	if (n <= 0) {

 		*terrno = errno;

 		Perror(statp, stderr, "read failed", errno);

 	  res_nclose(statp);

 		/*

 		 * A long running process might get its TCP

 		 * connection reset if the remote server was

 		 * restarted.  Requery the server instead of

 		 * trying a new one.  When there is only one

 		 * server, this means that a query might work

 		 * instead of failing.  We only allow one reset

 		 * per query to prevent looping.

 		 */

 		if (*terrno == ECONNRESET && !connreset) {

 			connreset = 1;

 			res_nclose(statp);

 			goto same_ns;

 		}

 		res_nclose(statp);

 		return (0);

 	}

 	resplen = ns_get16(ans);

 	if (resplen > anssiz) {

 		Dprint(statp->options & RES_DEBUG,

 		       (stdout, ";; response truncated\n")

 		       );

 		truncating = 1;

 		len = anssiz;

 	} else

 		len = resplen;

 	if (len < HFIXEDSZ) {

 		/*

 		 * Undersized message.

 		 */

 		Dprint(statp->options & RES_DEBUG,

 		       (stdout, ";; undersized: %d\n", len));

 		*terrno = EMSGSIZE;

 		res_nclose(statp);

 		return (0);

 	}

 	cp = ans;

 	while (len != 0 && (n = read(statp->_vcsock, (char *)cp, (size_t)len)) > 0){

 		cp += n;

 		len -= n;

 	}

 	if (n <= 0) {

 		*terrno = errno;

 		Perror(statp, stderr, "read(vc)", errno);

 		res_nclose(statp);

 		return (0);

 	}

 	if (truncating) {

 		/*

 		 * Flush rest of answer so connection stays in synch.

 		 */

 		anhp->tc = 1;

 		len = resplen - anssiz;

 		while (len != 0) {

 			char junk[PACKETSZ];

 			n = read(statp->_vcsock, junk,

 				 (len > sizeof junk) ? sizeof junk : len);

 			if (n > 0)

 				len -= n;

 			else

 				break;

 		}

 	}

 	/*

 	 * If the calling applicating has bailed out of

 	 * a previous call and failed to arrange to have

 	 * the circuit closed or the server has got

 	 * itself confused, then drop the packet and

 	 * wait for the correct one.

 	 */

 	if (hp->id != anhp->id) {

 		DprintQ((statp->options & RES_DEBUG) ||

 			(statp->pfcode & RES_PRF_REPLY),

 			(stdout, ";; old answer (unexpected):\n"),

 			ans, (resplen > anssiz) ? anssiz: resplen);

 		goto read_len;

 	}

 	/*

 	 * All is well, or the error is fatal.  Signal that the

 	 * next nameserver ought not be tried.

 	 */

 	return (resplen);

 }

 static int

 send_dg(res_state statp,

 	const u_char *buf, int buflen, u_char *ans, int anssiz,

 	int *terrno, int ns, int *v_circuit, int *gotsomewhere)

 {

 	const HEADER *hp = (const HEADER *)(const void *)buf;

 	HEADER *anhp = (HEADER *)(void *)ans;

 	const struct sockaddr *nsap;

 	int nsaplen;

 	struct timespec now, timeout, finish;

 	fd_set dsmask;

 	struct sockaddr_storage from;

 	socklen_t fromlen;

 	int resplen, seconds, n, s;

 	nsap = get_nsaddr(statp, (size_t)ns);

 	nsaplen = get_salen(nsap);

 	if (EXT(statp).nssocks[ns] == -1) {

 		EXT(statp).nssocks[ns] = socket(nsap->sa_family, SOCK_DGRAM, 0);

 		if (EXT(statp).nssocks[ns] > highestFD) {

 			res_nclose(statp);

 			errno = ENOTSOCK;

 		}

 		if (EXT(statp).nssocks[ns] < 0) {

 			switch (errno) {

 			case EPROTONOSUPPORT:

 #ifdef EPFNOSUPPORT

 			case EPFNOSUPPORT:

 #endif

 			case EAFNOSUPPORT:

 				Perror(statp, stderr, "socket(dg)", errno);

 				return (0);

 			default:

 				*terrno = errno;

 				Perror(statp, stderr, "socket(dg)", errno);

 				return (-1);

 			}

 		}

 #ifndef CANNOT_CONNECT_DGRAM

 		/*

 		 * On a 4.3BSD+ machine (client and server,

 		 * actually), sending to a nameserver datagram

 		 * port with no nameserver will cause an

 		 * ICMP port unreachable message to be returned.

 		 * If our datagram socket is "connected" to the

 		 * server, we get an ECONNREFUSED error on the next

 		 * socket operation, and select returns if the

 		 * error message is received.  We can thus detect

 		 * the absence of a nameserver without timing out.

 		 */

 		if (random_bind(EXT(statp).nssocks[ns], nsap->sa_family) < 0) {

 			Aerror(statp, stderr, "bind(dg)", errno, nsap,

 			    nsaplen);

 			res_nclose(statp);

 			return (0);

 		}

 		if (connect(EXT(statp).nssocks[ns], nsap, (socklen_t)nsaplen) < 0) {

 			Aerror(statp, stderr, "connect(dg)", errno, nsap,

 			    nsaplen);

 			res_nclose(statp);

 			return (0);

 		}

 #endif /* !CANNOT_CONNECT_DGRAM */

 		Dprint(statp->options & RES_DEBUG,

 		       (stdout, ";; new DG socket\n"))

 	}

 	s = EXT(statp).nssocks[ns];

 #ifndef CANNOT_CONNECT_DGRAM

 	if (send(s, (const char*)buf, (size_t)buflen, 0) != buflen) {

 		Perror(statp, stderr, "send", errno);

 		res_nclose(statp);

 		return (0);

 	}

 #else /* !CANNOT_CONNECT_DGRAM */

 	if (sendto(s, (const char*)buf, buflen, 0, nsap, nsaplen) != buflen)

 	{

 		Aerror(statp, stderr, "sendto", errno, nsap, nsaplen);

 		res_nclose(statp);

 		return (0);

 	}

 #endif /* !CANNOT_CONNECT_DGRAM */

 	/*

 	 * Wait for reply.

 	 */

 	seconds = (statp->retrans << ns);

 	if (ns > 0)

 		seconds /= statp->nscount;

 	if (seconds <= 0)

 		seconds = 1;

 	now = evNowTime();

 	timeout = evConsTime((long)seconds, 0L);

 	finish = evAddTime(now, timeout);

 	goto nonow;

  wait:

 	now = evNowTime();

  nonow:

 	FD_ZERO(&dsmask);

 	FD_SET(s, &dsmask);

 	if (evCmpTime(finish, now) > 0)

 		timeout = evSubTime(finish, now);

 	else

 		timeout = evConsTime(0L, 0L);

 	n = pselect(s + 1, &dsmask, NULL, NULL, &timeout, NULL);

 	if (n == 0) {

 		Dprint(statp->options & RES_DEBUG, (stdout, ";; timeout\n"));

 		*gotsomewhere = 1;

 		return (0);

 	}

 	if (n < 0) {

 		if (errno == EINTR)

 			goto wait;

 		Perror(statp, stderr, "select", errno);

 		res_nclose(statp);

 		return (0);

 	}

 	errno = 0;

 	fromlen = sizeof(from);

 	resplen = recvfrom(s, (char*)ans, (size_t)anssiz,0,

 			   (struct sockaddr *)(void *)&from, &fromlen);

 	if (resplen <= 0) {

 		Perror(statp, stderr, "recvfrom", errno);

 		res_nclose(statp);

 		return (0);

 	}

 	*gotsomewhere = 1;

 	if (resplen < HFIXEDSZ) {

 		/*

 		 * Undersized message.

 		 */

 		Dprint(statp->options & RES_DEBUG,

 		       (stdout, ";; undersized: %d\n",

 			resplen));

 		*terrno = EMSGSIZE;

 		res_nclose(statp);

 		return (0);

 	}

 	if (hp->id != anhp->id) {

 		/*

 		 * response from old query, ignore it.

 		 * XXX - potential security hazard could

 		 *	 be detected here.

 		 */

 		DprintQ((statp->options & RES_DEBUG) ||

 			(statp->pfcode & RES_PRF_REPLY),

 			(stdout, ";; old answer:\n"),

 			ans, (resplen > anssiz) ? anssiz : resplen);

 		goto wait;

 	}

 	if (!(statp->options & RES_INSECURE1) &&

 	    !res_ourserver_p(statp, (struct sockaddr *)(void *)&from)) {

 		/*

 		 * response from wrong server? ignore it.

 		 * XXX - potential security hazard could

 		 *	 be detected here.

 		 */

 		DprintQ((statp->options & RES_DEBUG) ||

 			(statp->pfcode & RES_PRF_REPLY),

 			(stdout, ";; not our server:\n"),

 			ans, (resplen > anssiz) ? anssiz : resplen);

 		goto wait;

 	}

 #ifdef RES_USE_EDNS0

 	if (anhp->rcode == FORMERR && (statp->options & RES_USE_EDNS0) != 0U) {

 		/*

 		 * Do not retry if the server do not understand EDNS0.

 		 * The case has to be captured here, as FORMERR packet do not

 		 * carry query section, hence res_queriesmatch() returns 0.

 		 */

 		DprintQ(statp->options & RES_DEBUG,

 			(stdout, "server rejected query with EDNS0:\n"),

 			ans, (resplen > anssiz) ? anssiz : resplen);

 		/* record the error */

 		statp->_flags |= RES_F_EDNS0ERR;

 		res_nclose(statp);

 		return (0);

 	}

 #endif

 	if (!(statp->options & RES_INSECURE2) &&

 	    !res_queriesmatch(buf, buf + buflen,

 			      ans, ans + anssiz)) {

 		/*

 		 * response contains wrong query? ignore it.

 		 * XXX - potential security hazard could

 		 *	 be detected here.

 		 */

 		DprintQ((statp->options & RES_DEBUG) ||

 			(statp->pfcode & RES_PRF_REPLY),

 			(stdout, ";; wrong query name:\n"),

 			ans, (resplen > anssiz) ? anssiz : resplen);

 		goto wait;

 	}

 	if (anhp->rcode == SERVFAIL ||

 	    anhp->rcode == NOTIMP ||

 	    anhp->rcode == REFUSED) {

 		DprintQ(statp->options & RES_DEBUG,

 			(stdout, "server rejected query:\n"),

 			ans, (resplen > anssiz) ? anssiz : resplen);

 		res_nclose(statp);

 		/* don't retry if called from dig */

 		if (!statp->pfcode)

 			return (0);

 	}

 	if (!(statp->options & RES_IGNTC) && anhp->tc) {

 		/*

 		 * To get the rest of answer,

 		 * use TCP with same server.

 		 */

 		Dprint(statp->options & RES_DEBUG,

 		       (stdout, ";; truncated answer\n"));

 		*v_circuit = 1;

 		res_nclose(statp);

 		return (1);

 	}

 	/*

 	 * All is well, or the error is fatal.  Signal that the

 	 * next nameserver ought not be tried.

 	 */

 	return (resplen);

 }

 static void

 Aerror(const res_state statp, FILE *file, const char *string, int error,

        const struct sockaddr *address, int alen)

 {

 	int save = errno;

 	char hbuf[NI_MAXHOST];

 	char sbuf[NI_MAXSERV];

 	alen = alen;

 	if ((statp->options & RES_DEBUG) != 0U) {

 		if (getnameinfo(address, (socklen_t)alen, hbuf, sizeof(hbuf),

 		    sbuf, sizeof(sbuf), niflags)) {

 			strncpy(hbuf, "?", sizeof(hbuf) - 1);

 			hbuf[sizeof(hbuf) - 1] = '\0';

 			strncpy(sbuf, "?", sizeof(sbuf) - 1);

 			sbuf[sizeof(sbuf) - 1] = '\0';

 		}

 		fprintf(file, "res_send: %s ([%s].%s): %s\n",

 			string, hbuf, sbuf, strerror(error));

 	}

 	errno = save;

 }

 static void

 Perror(const res_state statp, FILE *file, const char *string, int error) {

 	int save = errno;

 	if ((statp->options & RES_DEBUG) != 0U)

 		fprintf(file, "res_send: %s: %s\n",

 			string, strerror(error));

 	errno = save;

 }

 static int

 sock_eq(struct sockaddr *a, struct sockaddr *b) {

 	struct sockaddr_in *a4, *b4;

 	struct sockaddr_in6 *a6, *b6;

 	if (a->sa_family != b->sa_family)

 		return 0;

 	switch (a->sa_family) {

 	case AF_INET:

 		a4 = (struct sockaddr_in *)(void *)a;

 		b4 = (struct sockaddr_in *)(void *)b;

 		return a4->sin_port == b4->sin_port &&

 		    a4->sin_addr.s_addr == b4->sin_addr.s_addr;

 	case AF_INET6:

 		a6 = (struct sockaddr_in6 *)(void *)a;

 		b6 = (struct sockaddr_in6 *)(void *)b;

 		return a6->sin6_port == b6->sin6_port &&

 #ifdef HAVE_SIN6_SCOPE_ID

 		    a6->sin6_scope_id == b6->sin6_scope_id &&

 #endif

 		    IN6_ARE_ADDR_EQUAL(&a6->sin6_addr, &b6->sin6_addr);

 	default:

 		return 0;

 	}

 }

 #ifdef NEED_PSELECT

 /* XXX needs to move to the porting library. */

 static int

 pselect(int nfds, void *rfds, void *wfds, void *efds,

 	struct timespec *tsp, const sigset_t *sigmask)

 {

 	struct timeval tv, *tvp;

 	sigset_t sigs;

 	int n;

 	if (tsp) {

 		tvp = &tv;

 		tv = evTimeVal(*tsp);

 	} else

 		tvp = NULL;

 	if (sigmask)

 		sigprocmask(SIG_SETMASK, sigmask, &sigs);

 	n = select(nfds, rfds, wfds, efds, tvp);

 	if (sigmask)

 		sigprocmask(SIG_SETMASK, &sigs, NULL);

 	if (tsp)

 		*tsp = evTimeSpec(tv);

 	return (n);

 }

 #endif