1/*	$NetBSD$	*/
2
3/*
4 * Portions Copyright (C) 2004-2009  Internet Systems Consortium, Inc. ("ISC")
5 * Portions Copyright (C) 1996-2003  Internet Software Consortium.
6 *
7 * Permission to use, copy, modify, and/or distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
12 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
13 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
14 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
15 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
16 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
17 * PERFORMANCE OF THIS SOFTWARE.
18 */
19
20/*
21 * Copyright (c) 1985, 1989, 1993
22 *    The Regents of the University of California.  All rights reserved.
23 *
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
26 * are met:
27 * 1. Redistributions of source code must retain the above copyright
28 *    notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 *    notice, this list of conditions and the following disclaimer in the
31 *    documentation and/or other materials provided with the distribution.
32 * 3. All advertising materials mentioning features or use of this software
33 *    must display the following acknowledgement:
34 * 	This product includes software developed by the University of
35 * 	California, Berkeley and its contributors.
36 * 4. Neither the name of the University nor the names of its contributors
37 *    may be used to endorse or promote products derived from this software
38 *    without specific prior written permission.
39 *
40 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50 * SUCH DAMAGE.
51 */
52
53/*
54 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
55 *
56 * Permission to use, copy, modify, and distribute this software for any
57 * purpose with or without fee is hereby granted, provided that the above
58 * copyright notice and this permission notice appear in all copies, and that
59 * the name of Digital Equipment Corporation not be used in advertising or
60 * publicity pertaining to distribution of the document or software without
61 * specific, written prior permission.
62 *
63 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
64 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
65 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
66 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
67 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
68 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
69 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
70 * SOFTWARE.
71 */
72
73#if defined(LIBC_SCCS) && !defined(lint)
74static const char sccsid[] = "@(#)res_send.c	8.1 (Berkeley) 6/4/93";
75static const char rcsid[] = "Id: res_send.c,v 1.22 2009/01/22 23:49:23 tbox Exp ";
76#endif /* LIBC_SCCS and not lint */
77
78/*! \file
79 * \brief
80 * Send query to name server and wait for reply.
81 */
82
83#include "port_before.h"
84#include "fd_setsize.h"
85
86#include <sys/types.h>
87#include <sys/param.h>
88#include <sys/time.h>
89#include <sys/socket.h>
90#include <sys/uio.h>
91
92#include <netinet/in.h>
93#include <arpa/nameser.h>
94#include <arpa/inet.h>
95
96#include <errno.h>
97#include <netdb.h>
98#include <resolv.h>
99#include <signal.h>
100#include <stdio.h>
101#include <stdlib.h>
102#include <string.h>
103#include <unistd.h>
104
105#include <isc/eventlib.h>
106
107#include "port_after.h"
108
109#ifdef USE_POLL
110#ifdef HAVE_STROPTS_H
111#include <stropts.h>
112#endif
113#include <poll.h>
114#endif /* USE_POLL */
115
116/* Options.  Leave them on. */
117#define DEBUG
118#include "res_debug.h"
119#include "res_private.h"
120
121#define EXT(res) ((res)->_u._ext)
122
123#ifndef USE_POLL
124static const int highestFD = FD_SETSIZE - 1;
125#else
126static int highestFD = 0;
127#endif
128
129/* Forward. */
130
131static int		get_salen __P((const struct sockaddr *));
132static struct sockaddr * get_nsaddr __P((res_state, size_t));
133static int		send_vc(res_state, const u_char *, int,
134				u_char *, int, int *, int);
135static int		send_dg(res_state, const u_char *, int,
136				u_char *, int, int *, int, int,
137				int *, int *);
138static void		Aerror(const res_state, FILE *, const char *, int,
139			       const struct sockaddr *, int);
140static void		Perror(const res_state, FILE *, const char *, int);
141static int		sock_eq(struct sockaddr *, struct sockaddr *);
142#if defined(NEED_PSELECT) && !defined(USE_POLL)
143static int		pselect(int, void *, void *, void *,
144				struct timespec *,
145				const sigset_t *);
146#endif
147void res_pquery(const res_state, const u_char *, int, FILE *);
148
149static const int niflags = NI_NUMERICHOST | NI_NUMERICSERV;
150
151/* Public. */
152
153/*%
154 *	looks up "ina" in _res.ns_addr_list[]
155 *
156 * returns:
157 *\li	0  : not found
158 *\li	>0 : found
159 *
160 * author:
161 *\li	paul vixie, 29may94
162 */
163int
164res_ourserver_p(const res_state statp, const struct sockaddr *sa) {
165	const struct sockaddr_in *inp, *srv;
166	const struct sockaddr_in6 *in6p, *srv6;
167	int ns;
168
169	switch (sa->sa_family) {
170	case AF_INET:
171		inp = (const struct sockaddr_in *)sa;
172		for (ns = 0;  ns < statp->nscount;  ns++) {
173			srv = (struct sockaddr_in *)get_nsaddr(statp, ns);
174			if (srv->sin_family == inp->sin_family &&
175			    srv->sin_port == inp->sin_port &&
176			    (srv->sin_addr.s_addr == INADDR_ANY ||
177			     srv->sin_addr.s_addr == inp->sin_addr.s_addr))
178				return (1);
179		}
180		break;
181	case AF_INET6:
182		if (EXT(statp).ext == NULL)
183			break;
184		in6p = (const struct sockaddr_in6 *)sa;
185		for (ns = 0;  ns < statp->nscount;  ns++) {
186			srv6 = (struct sockaddr_in6 *)get_nsaddr(statp, ns);
187			if (srv6->sin6_family == in6p->sin6_family &&
188			    srv6->sin6_port == in6p->sin6_port &&
189#ifdef HAVE_SIN6_SCOPE_ID
190			    (srv6->sin6_scope_id == 0 ||
191			     srv6->sin6_scope_id == in6p->sin6_scope_id) &&
192#endif
193			    (IN6_IS_ADDR_UNSPECIFIED(&srv6->sin6_addr) ||
194			     IN6_ARE_ADDR_EQUAL(&srv6->sin6_addr, &in6p->sin6_addr)))
195				return (1);
196		}
197		break;
198	default:
199		break;
200	}
201	return (0);
202}
203
204/*%
205 *	look for (name,type,class) in the query section of packet (buf,eom)
206 *
207 * requires:
208 *\li	buf + HFIXEDSZ <= eom
209 *
210 * returns:
211 *\li	-1 : format error
212 *\li	0  : not found
213 *\li	>0 : found
214 *
215 * author:
216 *\li	paul vixie, 29may94
217 */
218int
219res_nameinquery(const char *name, int type, int class,
220		const u_char *buf, const u_char *eom)
221{
222	const u_char *cp = buf + HFIXEDSZ;
223	int qdcount = ntohs(((const HEADER*)buf)->qdcount);
224
225	while (qdcount-- > 0) {
226		char tname[MAXDNAME+1];
227		int n, ttype, tclass;
228
229		n = dn_expand(buf, eom, cp, tname, sizeof tname);
230		if (n < 0)
231			return (-1);
232		cp += n;
233		if (cp + 2 * INT16SZ > eom)
234			return (-1);
235		ttype = ns_get16(cp); cp += INT16SZ;
236		tclass = ns_get16(cp); cp += INT16SZ;
237		if (ttype == type && tclass == class &&
238		    ns_samename(tname, name) == 1)
239			return (1);
240	}
241	return (0);
242}
243
244/*%
245 *	is there a 1:1 mapping of (name,type,class)
246 *	in (buf1,eom1) and (buf2,eom2)?
247 *
248 * returns:
249 *\li	-1 : format error
250 *\li	0  : not a 1:1 mapping
251 *\li	>0 : is a 1:1 mapping
252 *
253 * author:
254 *\li	paul vixie, 29may94
255 */
256int
257res_queriesmatch(const u_char *buf1, const u_char *eom1,
258		 const u_char *buf2, const u_char *eom2)
259{
260	const u_char *cp = buf1 + HFIXEDSZ;
261	int qdcount = ntohs(((const HEADER*)buf1)->qdcount);
262
263	if (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2)
264		return (-1);
265
266	/*
267	 * Only header section present in replies to
268	 * dynamic update packets.
269	 */
270	if ((((const HEADER *)buf1)->opcode == ns_o_update) &&
271	    (((const HEADER *)buf2)->opcode == ns_o_update))
272		return (1);
273
274	if (qdcount != ntohs(((const HEADER*)buf2)->qdcount))
275		return (0);
276	while (qdcount-- > 0) {
277		char tname[MAXDNAME+1];
278		int n, ttype, tclass;
279
280		n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
281		if (n < 0)
282			return (-1);
283		cp += n;
284		if (cp + 2 * INT16SZ > eom1)
285			return (-1);
286		ttype = ns_get16(cp);	cp += INT16SZ;
287		tclass = ns_get16(cp); cp += INT16SZ;
288		if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
289			return (0);
290	}
291	return (1);
292}
293
294int
295res_nsend(res_state statp,
296	  const u_char *buf, int buflen, u_char *ans, int anssiz)
297{
298	int gotsomewhere, terrno, tries, v_circuit, resplen, ns, n;
299	char abuf[NI_MAXHOST];
300
301#ifdef USE_POLL
302	highestFD = sysconf(_SC_OPEN_MAX) - 1;
303#endif
304
305	/* No name servers or res_init() failure */
306	if (statp->nscount == 0 || EXT(statp).ext == NULL) {
307		errno = ESRCH;
308		return (-1);
309	}
310	if (anssiz < HFIXEDSZ) {
311		errno = EINVAL;
312		return (-1);
313	}
314	DprintQ((statp->options & RES_DEBUG) || (statp->pfcode & RES_PRF_QUERY),
315		(stdout, ";; res_send()\n"), buf, buflen);
316	v_circuit = (statp->options & RES_USEVC) || buflen > PACKETSZ;
317	gotsomewhere = 0;
318	terrno = ETIMEDOUT;
319
320	/*
321	 * If the ns_addr_list in the resolver context has changed, then
322	 * invalidate our cached copy and the associated timing data.
323	 */
324	if (EXT(statp).nscount != 0) {
325		int needclose = 0;
326		struct sockaddr_storage peer;
327		ISC_SOCKLEN_T peerlen;
328
329		if (EXT(statp).nscount != statp->nscount)
330			needclose++;
331		else
332			for (ns = 0; ns < statp->nscount; ns++) {
333				if (statp->nsaddr_list[ns].sin_family &&
334				    !sock_eq((struct sockaddr *)&statp->nsaddr_list[ns],
335					     (struct sockaddr *)&EXT(statp).ext->nsaddrs[ns])) {
336					needclose++;
337					break;
338				}
339
340				if (EXT(statp).nssocks[ns] == -1)
341					continue;
342				peerlen = sizeof(peer);
343				if (getpeername(EXT(statp).nssocks[ns],
344				    (struct sockaddr *)&peer, &peerlen) < 0) {
345					needclose++;
346					break;
347				}
348				if (!sock_eq((struct sockaddr *)&peer,
349				    get_nsaddr(statp, ns))) {
350					needclose++;
351					break;
352				}
353			}
354		if (needclose) {
355			res_nclose(statp);
356			EXT(statp).nscount = 0;
357		}
358	}
359
360	/*
361	 * Maybe initialize our private copy of the ns_addr_list.
362	 */
363	if (EXT(statp).nscount == 0) {
364		for (ns = 0; ns < statp->nscount; ns++) {
365			EXT(statp).nstimes[ns] = RES_MAXTIME;
366			EXT(statp).nssocks[ns] = -1;
367			if (!statp->nsaddr_list[ns].sin_family)
368				continue;
369			EXT(statp).ext->nsaddrs[ns].sin =
370				 statp->nsaddr_list[ns];
371		}
372		EXT(statp).nscount = statp->nscount;
373	}
374
375	/*
376	 * Some resolvers want to even out the load on their nameservers.
377	 * Note that RES_BLAST overrides RES_ROTATE.
378	 */
379	if ((statp->options & RES_ROTATE) != 0U &&
380	    (statp->options & RES_BLAST) == 0U) {
381		union res_sockaddr_union inu;
382		struct sockaddr_in ina;
383		int lastns = statp->nscount - 1;
384		int fd;
385		u_int16_t nstime;
386
387		if (EXT(statp).ext != NULL)
388			inu = EXT(statp).ext->nsaddrs[0];
389		ina = statp->nsaddr_list[0];
390		fd = EXT(statp).nssocks[0];
391		nstime = EXT(statp).nstimes[0];
392		for (ns = 0; ns < lastns; ns++) {
393			if (EXT(statp).ext != NULL)
394				EXT(statp).ext->nsaddrs[ns] =
395					EXT(statp).ext->nsaddrs[ns + 1];
396			statp->nsaddr_list[ns] = statp->nsaddr_list[ns + 1];
397			EXT(statp).nssocks[ns] = EXT(statp).nssocks[ns + 1];
398			EXT(statp).nstimes[ns] = EXT(statp).nstimes[ns + 1];
399		}
400		if (EXT(statp).ext != NULL)
401			EXT(statp).ext->nsaddrs[lastns] = inu;
402		statp->nsaddr_list[lastns] = ina;
403		EXT(statp).nssocks[lastns] = fd;
404		EXT(statp).nstimes[lastns] = nstime;
405	}
406
407	/*
408	 * Send request, RETRY times, or until successful.
409	 */
410	for (tries = 0; tries < statp->retry; tries++) {
411	    for (ns = 0; ns < statp->nscount; ns++) {
412		struct sockaddr *nsap;
413		int nsaplen;
414		nsap = get_nsaddr(statp, ns);
415		nsaplen = get_salen(nsap);
416		statp->_flags &= ~RES_F_LASTMASK;
417		statp->_flags |= (ns << RES_F_LASTSHIFT);
418 same_ns:
419		if (statp->qhook) {
420			int done = 0, loops = 0;
421
422			do {
423				res_sendhookact act;
424
425				act = (*statp->qhook)(&nsap, &buf, &buflen,
426						      ans, anssiz, &resplen);
427				switch (act) {
428				case res_goahead:
429					done = 1;
430					break;
431				case res_nextns:
432					res_nclose(statp);
433					goto next_ns;
434				case res_done:
435					return (resplen);
436				case res_modified:
437					/* give the hook another try */
438					if (++loops < 42) /*doug adams*/
439						break;
440					/*FALLTHROUGH*/
441				case res_error:
442					/*FALLTHROUGH*/
443				default:
444					goto fail;
445				}
446			} while (!done);
447		}
448
449		Dprint(((statp->options & RES_DEBUG) &&
450			getnameinfo(nsap, nsaplen, abuf, sizeof(abuf),
451				    NULL, 0, niflags) == 0),
452		       (stdout, ";; Querying server (# %d) address = %s\n",
453			ns + 1, abuf));
454
455
456		if (v_circuit) {
457			/* Use VC; at most one attempt per server. */
458			tries = statp->retry;
459			n = send_vc(statp, buf, buflen, ans, anssiz, &terrno,
460				    ns);
461			if (n < 0)
462				goto fail;
463			if (n == 0)
464				goto next_ns;
465			resplen = n;
466		} else {
467			/* Use datagrams. */
468			n = send_dg(statp, buf, buflen, ans, anssiz, &terrno,
469				    ns, tries, &v_circuit, &gotsomewhere);
470			if (n < 0)
471				goto fail;
472			if (n == 0)
473				goto next_ns;
474			if (v_circuit)
475				goto same_ns;
476			resplen = n;
477		}
478
479		Dprint((statp->options & RES_DEBUG) ||
480		       ((statp->pfcode & RES_PRF_REPLY) &&
481			(statp->pfcode & RES_PRF_HEAD1)),
482		       (stdout, ";; got answer:\n"));
483
484		DprintQ((statp->options & RES_DEBUG) ||
485			(statp->pfcode & RES_PRF_REPLY),
486			(stdout, "%s", ""),
487			ans, (resplen > anssiz) ? anssiz : resplen);
488
489		/*
490		 * If we have temporarily opened a virtual circuit,
491		 * or if we haven't been asked to keep a socket open,
492		 * close the socket.
493		 */
494		if ((v_circuit && (statp->options & RES_USEVC) == 0U) ||
495		    (statp->options & RES_STAYOPEN) == 0U) {
496			res_nclose(statp);
497		}
498		if (statp->rhook) {
499			int done = 0, loops = 0;
500
501			do {
502				res_sendhookact act;
503
504				act = (*statp->rhook)(nsap, buf, buflen,
505						      ans, anssiz, &resplen);
506				switch (act) {
507				case res_goahead:
508				case res_done:
509					done = 1;
510					break;
511				case res_nextns:
512					res_nclose(statp);
513					goto next_ns;
514				case res_modified:
515					/* give the hook another try */
516					if (++loops < 42) /*doug adams*/
517						break;
518					/*FALLTHROUGH*/
519				case res_error:
520					/*FALLTHROUGH*/
521				default:
522					goto fail;
523				}
524			} while (!done);
525
526		}
527		return (resplen);
528 next_ns: ;
529	   } /*foreach ns*/
530	} /*foreach retry*/
531	res_nclose(statp);
532	if (!v_circuit) {
533		if (!gotsomewhere)
534			errno = ECONNREFUSED;	/*%< no nameservers found */
535		else
536			errno = ETIMEDOUT;	/*%< no answer obtained */
537	} else
538		errno = terrno;
539	return (-1);
540 fail:
541	res_nclose(statp);
542	return (-1);
543}
544
545/* Private */
546
547static int
548get_salen(sa)
549	const struct sockaddr *sa;
550{
551
552#ifdef HAVE_SA_LEN
553	/* There are people do not set sa_len.  Be forgiving to them. */
554	if (sa->sa_len)
555		return (sa->sa_len);
556#endif
557
558	if (sa->sa_family == AF_INET)
559		return (sizeof(struct sockaddr_in));
560	else if (sa->sa_family == AF_INET6)
561		return (sizeof(struct sockaddr_in6));
562	else
563		return (0);	/*%< unknown, die on connect */
564}
565
566/*%
567 * pick appropriate nsaddr_list for use.  see res_init() for initialization.
568 */
569static struct sockaddr *
570get_nsaddr(statp, n)
571	res_state statp;
572	size_t n;
573{
574
575	if (!statp->nsaddr_list[n].sin_family && EXT(statp).ext) {
576		/*
577		 * - EXT(statp).ext->nsaddrs[n] holds an address that is larger
578		 *   than struct sockaddr, and
579		 * - user code did not update statp->nsaddr_list[n].
580		 */
581		return (struct sockaddr *)(void *)&EXT(statp).ext->nsaddrs[n];
582	} else {
583		/*
584		 * - user code updated statp->nsaddr_list[n], or
585		 * - statp->nsaddr_list[n] has the same content as
586		 *   EXT(statp).ext->nsaddrs[n].
587		 */
588		return (struct sockaddr *)(void *)&statp->nsaddr_list[n];
589	}
590}
591
592static int
593send_vc(res_state statp,
594	const u_char *buf, int buflen, u_char *ans, int anssiz,
595	int *terrno, int ns)
596{
597	const HEADER *hp = (const HEADER *) buf;
598	HEADER *anhp = (HEADER *) ans;
599	struct sockaddr *nsap;
600	int nsaplen;
601	int truncating, connreset, resplen, n;
602	struct iovec iov[2];
603	u_short len;
604	u_char *cp;
605	void *tmp;
606#ifdef SO_NOSIGPIPE
607	int on = 1;
608#endif
609
610	nsap = get_nsaddr(statp, ns);
611	nsaplen = get_salen(nsap);
612
613	connreset = 0;
614 same_ns:
615	truncating = 0;
616
617	/* Are we still talking to whom we want to talk to? */
618	if (statp->_vcsock >= 0 && (statp->_flags & RES_F_VC) != 0) {
619		struct sockaddr_storage peer;
620		ISC_SOCKLEN_T size = sizeof peer;
621
622		if (getpeername(statp->_vcsock,
623				(struct sockaddr *)&peer, &size) < 0 ||
624		    !sock_eq((struct sockaddr *)&peer, nsap)) {
625			res_nclose(statp);
626			statp->_flags &= ~RES_F_VC;
627		}
628	}
629
630	if (statp->_vcsock < 0 || (statp->_flags & RES_F_VC) == 0) {
631		if (statp->_vcsock >= 0)
632			res_nclose(statp);
633
634		statp->_vcsock = socket(nsap->sa_family, SOCK_STREAM, 0);
635		if (statp->_vcsock > highestFD) {
636			res_nclose(statp);
637			errno = ENOTSOCK;
638		}
639		if (statp->_vcsock < 0) {
640			switch (errno) {
641			case EPROTONOSUPPORT:
642#ifdef EPFNOSUPPORT
643			case EPFNOSUPPORT:
644#endif
645			case EAFNOSUPPORT:
646				Perror(statp, stderr, "socket(vc)", errno);
647				return (0);
648			default:
649				*terrno = errno;
650				Perror(statp, stderr, "socket(vc)", errno);
651				return (-1);
652			}
653		}
654#ifdef SO_NOSIGPIPE
655		/*
656		 * Disable generation of SIGPIPE when writing to a closed
657		 * socket.  Write should return -1 and set errno to EPIPE
658		 * instead.
659		 *
660		 * Push on even if setsockopt(SO_NOSIGPIPE) fails.
661		 */
662		(void)setsockopt(statp->_vcsock, SOL_SOCKET, SO_NOSIGPIPE, &on,
663				 sizeof(on));
664#endif
665		errno = 0;
666		if (connect(statp->_vcsock, nsap, nsaplen) < 0) {
667			*terrno = errno;
668			Aerror(statp, stderr, "connect/vc", errno, nsap,
669			    nsaplen);
670			res_nclose(statp);
671			return (0);
672		}
673		statp->_flags |= RES_F_VC;
674	}
675
676	/*
677	 * Send length & message
678	 */
679	ns_put16((u_short)buflen, (u_char*)&len);
680	iov[0] = evConsIovec(&len, INT16SZ);
681	DE_CONST(buf, tmp);
682	iov[1] = evConsIovec(tmp, buflen);
683	if (writev(statp->_vcsock, iov, 2) != (INT16SZ + buflen)) {
684		*terrno = errno;
685		Perror(statp, stderr, "write failed", errno);
686		res_nclose(statp);
687		return (0);
688	}
689	/*
690	 * Receive length & response
691	 */
692 read_len:
693	cp = ans;
694	len = INT16SZ;
695	while ((n = read(statp->_vcsock, (char *)cp, (int)len)) > 0) {
696		cp += n;
697		if ((len -= n) == 0)
698			break;
699	}
700	if (n <= 0) {
701		*terrno = errno;
702		Perror(statp, stderr, "read failed", errno);
703		res_nclose(statp);
704		/*
705		 * A long running process might get its TCP
706		 * connection reset if the remote server was
707		 * restarted.  Requery the server instead of
708		 * trying a new one.  When there is only one
709		 * server, this means that a query might work
710		 * instead of failing.  We only allow one reset
711		 * per query to prevent looping.
712		 */
713		if (*terrno == ECONNRESET && !connreset) {
714			connreset = 1;
715			res_nclose(statp);
716			goto same_ns;
717		}
718		res_nclose(statp);
719		return (0);
720	}
721	resplen = ns_get16(ans);
722	if (resplen > anssiz) {
723		Dprint(statp->options & RES_DEBUG,
724		       (stdout, ";; response truncated\n")
725		       );
726		truncating = 1;
727		len = anssiz;
728	} else
729		len = resplen;
730	if (len < HFIXEDSZ) {
731		/*
732		 * Undersized message.
733		 */
734		Dprint(statp->options & RES_DEBUG,
735		       (stdout, ";; undersized: %d\n", len));
736		*terrno = EMSGSIZE;
737		res_nclose(statp);
738		return (0);
739	}
740	cp = ans;
741	while (len != 0 && (n = read(statp->_vcsock, (char *)cp, (int)len)) > 0){
742		cp += n;
743		len -= n;
744	}
745	if (n <= 0) {
746		*terrno = errno;
747		Perror(statp, stderr, "read(vc)", errno);
748		res_nclose(statp);
749		return (0);
750	}
751	if (truncating) {
752		/*
753		 * Flush rest of answer so connection stays in synch.
754		 */
755		anhp->tc = 1;
756		len = resplen - anssiz;
757		while (len != 0) {
758			char junk[PACKETSZ];
759
760			n = read(statp->_vcsock, junk,
761				 (len > sizeof junk) ? sizeof junk : len);
762			if (n > 0)
763				len -= n;
764			else
765				break;
766		}
767	}
768	/*
769	 * If the calling applicating has bailed out of
770	 * a previous call and failed to arrange to have
771	 * the circuit closed or the server has got
772	 * itself confused, then drop the packet and
773	 * wait for the correct one.
774	 */
775	if (hp->id != anhp->id) {
776		DprintQ((statp->options & RES_DEBUG) ||
777			(statp->pfcode & RES_PRF_REPLY),
778			(stdout, ";; old answer (unexpected):\n"),
779			ans, (resplen > anssiz) ? anssiz: resplen);
780		goto read_len;
781	}
782
783	/*
784	 * All is well, or the error is fatal.  Signal that the
785	 * next nameserver ought not be tried.
786	 */
787	return (resplen);
788}
789
790static int
791send_dg(res_state statp, const u_char *buf, int buflen, u_char *ans,
792	int anssiz, int *terrno, int ns, int tries, int *v_circuit,
793	int *gotsomewhere)
794{
795	const HEADER *hp = (const HEADER *) buf;
796	HEADER *anhp = (HEADER *) ans;
797	const struct sockaddr *nsap;
798	int nsaplen;
799	struct timespec now, timeout, finish;
800	struct sockaddr_storage from;
801	ISC_SOCKLEN_T fromlen;
802	int resplen, seconds, n, s;
803#ifdef USE_POLL
804	int     polltimeout;
805	struct pollfd   pollfd;
806#else
807	fd_set dsmask;
808#endif
809
810	nsap = get_nsaddr(statp, ns);
811	nsaplen = get_salen(nsap);
812	if (EXT(statp).nssocks[ns] == -1) {
813		EXT(statp).nssocks[ns] = socket(nsap->sa_family, SOCK_DGRAM, 0);
814		if (EXT(statp).nssocks[ns] > highestFD) {
815			res_nclose(statp);
816			errno = ENOTSOCK;
817		}
818		if (EXT(statp).nssocks[ns] < 0) {
819			switch (errno) {
820			case EPROTONOSUPPORT:
821#ifdef EPFNOSUPPORT
822			case EPFNOSUPPORT:
823#endif
824			case EAFNOSUPPORT:
825				Perror(statp, stderr, "socket(dg)", errno);
826				return (0);
827			default:
828				*terrno = errno;
829				Perror(statp, stderr, "socket(dg)", errno);
830				return (-1);
831			}
832		}
833#ifndef CANNOT_CONNECT_DGRAM
834		/*
835		 * On a 4.3BSD+ machine (client and server,
836		 * actually), sending to a nameserver datagram
837		 * port with no nameserver will cause an
838		 * ICMP port unreachable message to be returned.
839		 * If our datagram socket is "connected" to the
840		 * server, we get an ECONNREFUSED error on the next
841		 * socket operation, and select returns if the
842		 * error message is received.  We can thus detect
843		 * the absence of a nameserver without timing out.
844		 */
845		if (connect(EXT(statp).nssocks[ns], nsap, nsaplen) < 0) {
846			Aerror(statp, stderr, "connect(dg)", errno, nsap,
847			    nsaplen);
848			res_nclose(statp);
849			return (0);
850		}
851#endif /* !CANNOT_CONNECT_DGRAM */
852		Dprint(statp->options & RES_DEBUG,
853		       (stdout, ";; new DG socket\n"))
854	}
855	s = EXT(statp).nssocks[ns];
856#ifndef CANNOT_CONNECT_DGRAM
857	if (send(s, (const char*)buf, buflen, 0) != buflen) {
858		Perror(statp, stderr, "send", errno);
859		res_nclose(statp);
860		return (0);
861	}
862#else /* !CANNOT_CONNECT_DGRAM */
863	if (sendto(s, (const char*)buf, buflen, 0, nsap, nsaplen) != buflen)
864	{
865		Aerror(statp, stderr, "sendto", errno, nsap, nsaplen);
866		res_nclose(statp);
867		return (0);
868	}
869#endif /* !CANNOT_CONNECT_DGRAM */
870
871	/*
872	 * Wait for reply.
873	 */
874	seconds = (statp->retrans << tries);
875	if (ns > 0)
876		seconds /= statp->nscount;
877	if (seconds <= 0)
878		seconds = 1;
879	now = evNowTime();
880	timeout = evConsTime(seconds, 0);
881	finish = evAddTime(now, timeout);
882	goto nonow;
883 wait:
884	now = evNowTime();
885 nonow:
886#ifndef USE_POLL
887	FD_ZERO(&dsmask);
888	FD_SET(s, &dsmask);
889	if (evCmpTime(finish, now) > 0)
890		timeout = evSubTime(finish, now);
891	else
892		timeout = evConsTime(0, 0);
893	n = pselect(s + 1, &dsmask, NULL, NULL, &timeout, NULL);
894#else
895	timeout = evSubTime(finish, now);
896	if (timeout.tv_sec < 0)
897		timeout = evConsTime(0, 0);
898	polltimeout = 1000*timeout.tv_sec +
899		timeout.tv_nsec/1000000;
900	pollfd.fd = s;
901	pollfd.events = POLLRDNORM;
902	n = poll(&pollfd, 1, polltimeout);
903#endif /* USE_POLL */
904
905	if (n == 0) {
906		Dprint(statp->options & RES_DEBUG, (stdout, ";; timeout\n"));
907		*gotsomewhere = 1;
908		return (0);
909	}
910	if (n < 0) {
911		if (errno == EINTR)
912			goto wait;
913#ifndef USE_POLL
914		Perror(statp, stderr, "select", errno);
915#else
916		Perror(statp, stderr, "poll", errno);
917#endif /* USE_POLL */
918		res_nclose(statp);
919		return (0);
920	}
921	errno = 0;
922	fromlen = sizeof(from);
923	resplen = recvfrom(s, (char*)ans, anssiz,0,
924			   (struct sockaddr *)&from, &fromlen);
925	if (resplen <= 0) {
926		Perror(statp, stderr, "recvfrom", errno);
927		res_nclose(statp);
928		return (0);
929	}
930	*gotsomewhere = 1;
931	if (resplen < HFIXEDSZ) {
932		/*
933		 * Undersized message.
934		 */
935		Dprint(statp->options & RES_DEBUG,
936		       (stdout, ";; undersized: %d\n",
937			resplen));
938		*terrno = EMSGSIZE;
939		res_nclose(statp);
940		return (0);
941	}
942	if (hp->id != anhp->id) {
943		/*
944		 * response from old query, ignore it.
945		 * XXX - potential security hazard could
946		 *	 be detected here.
947		 */
948		DprintQ((statp->options & RES_DEBUG) ||
949			(statp->pfcode & RES_PRF_REPLY),
950			(stdout, ";; old answer:\n"),
951			ans, (resplen > anssiz) ? anssiz : resplen);
952		goto wait;
953	}
954	if (!(statp->options & RES_INSECURE1) &&
955	    !res_ourserver_p(statp, (struct sockaddr *)&from)) {
956		/*
957		 * response from wrong server? ignore it.
958		 * XXX - potential security hazard could
959		 *	 be detected here.
960		 */
961		DprintQ((statp->options & RES_DEBUG) ||
962			(statp->pfcode & RES_PRF_REPLY),
963			(stdout, ";; not our server:\n"),
964			ans, (resplen > anssiz) ? anssiz : resplen);
965		goto wait;
966	}
967#ifdef RES_USE_EDNS0
968	if (anhp->rcode == FORMERR && (statp->options & RES_USE_EDNS0) != 0U) {
969		/*
970		 * Do not retry if the server do not understand EDNS0.
971		 * The case has to be captured here, as FORMERR packet do not
972		 * carry query section, hence res_queriesmatch() returns 0.
973		 */
974		DprintQ(statp->options & RES_DEBUG,
975			(stdout, "server rejected query with EDNS0:\n"),
976			ans, (resplen > anssiz) ? anssiz : resplen);
977		/* record the error */
978		statp->_flags |= RES_F_EDNS0ERR;
979		res_nclose(statp);
980		return (0);
981	}
982#endif
983	if (!(statp->options & RES_INSECURE2) &&
984	    !res_queriesmatch(buf, buf + buflen,
985			      ans, ans + anssiz)) {
986		/*
987		 * response contains wrong query? ignore it.
988		 * XXX - potential security hazard could
989		 *	 be detected here.
990		 */
991		DprintQ((statp->options & RES_DEBUG) ||
992			(statp->pfcode & RES_PRF_REPLY),
993			(stdout, ";; wrong query name:\n"),
994			ans, (resplen > anssiz) ? anssiz : resplen);
995		goto wait;
996	}
997	if (anhp->rcode == SERVFAIL ||
998	    anhp->rcode == NOTIMP ||
999	    anhp->rcode == REFUSED) {
1000		DprintQ(statp->options & RES_DEBUG,
1001			(stdout, "server rejected query:\n"),
1002			ans, (resplen > anssiz) ? anssiz : resplen);
1003		res_nclose(statp);
1004		/* don't retry if called from dig */
1005		if (!statp->pfcode)
1006			return (0);
1007	}
1008	if (!(statp->options & RES_IGNTC) && anhp->tc) {
1009		/*
1010		 * To get the rest of answer,
1011		 * use TCP with same server.
1012		 */
1013		Dprint(statp->options & RES_DEBUG,
1014		       (stdout, ";; truncated answer\n"));
1015		*v_circuit = 1;
1016		res_nclose(statp);
1017		return (1);
1018	}
1019	/*
1020	 * All is well, or the error is fatal.  Signal that the
1021	 * next nameserver ought not be tried.
1022	 */
1023	return (resplen);
1024}
1025
1026static void
1027Aerror(const res_state statp, FILE *file, const char *string, int error,
1028       const struct sockaddr *address, int alen)
1029{
1030	int save = errno;
1031	char hbuf[NI_MAXHOST];
1032	char sbuf[NI_MAXSERV];
1033
1034	alen = alen;
1035
1036	if ((statp->options & RES_DEBUG) != 0U) {
1037		if (getnameinfo(address, alen, hbuf, sizeof(hbuf),
1038		    sbuf, sizeof(sbuf), niflags)) {
1039			strncpy(hbuf, "?", sizeof(hbuf) - 1);
1040			hbuf[sizeof(hbuf) - 1] = '\0';
1041			strncpy(sbuf, "?", sizeof(sbuf) - 1);
1042			sbuf[sizeof(sbuf) - 1] = '\0';
1043		}
1044		fprintf(file, "res_send: %s ([%s].%s): %s\n",
1045			string, hbuf, sbuf, strerror(error));
1046	}
1047	errno = save;
1048}
1049
1050static void
1051Perror(const res_state statp, FILE *file, const char *string, int error) {
1052	int save = errno;
1053
1054	if ((statp->options & RES_DEBUG) != 0U)
1055		fprintf(file, "res_send: %s: %s\n",
1056			string, strerror(error));
1057	errno = save;
1058}
1059
1060static int
1061sock_eq(struct sockaddr *a, struct sockaddr *b) {
1062	struct sockaddr_in *a4, *b4;
1063	struct sockaddr_in6 *a6, *b6;
1064
1065	if (a->sa_family != b->sa_family)
1066		return 0;
1067	switch (a->sa_family) {
1068	case AF_INET:
1069		a4 = (struct sockaddr_in *)a;
1070		b4 = (struct sockaddr_in *)b;
1071		return a4->sin_port == b4->sin_port &&
1072		    a4->sin_addr.s_addr == b4->sin_addr.s_addr;
1073	case AF_INET6:
1074		a6 = (struct sockaddr_in6 *)a;
1075		b6 = (struct sockaddr_in6 *)b;
1076		return a6->sin6_port == b6->sin6_port &&
1077#ifdef HAVE_SIN6_SCOPE_ID
1078		    a6->sin6_scope_id == b6->sin6_scope_id &&
1079#endif
1080		    IN6_ARE_ADDR_EQUAL(&a6->sin6_addr, &b6->sin6_addr);
1081	default:
1082		return 0;
1083	}
1084}
1085
1086#if defined(NEED_PSELECT) && !defined(USE_POLL)
1087/* XXX needs to move to the porting library. */
1088static int
1089pselect(int nfds, void *rfds, void *wfds, void *efds,
1090	struct timespec *tsp, const sigset_t *sigmask)
1091{
1092	struct timeval tv, *tvp;
1093	sigset_t sigs;
1094	int n;
1095
1096	if (tsp) {
1097		tvp = &tv;
1098		tv = evTimeVal(*tsp);
1099	} else
1100		tvp = NULL;
1101	if (sigmask)
1102		sigprocmask(SIG_SETMASK, sigmask, &sigs);
1103	n = select(nfds, rfds, wfds, efds, tvp);
1104	if (sigmask)
1105		sigprocmask(SIG_SETMASK, &sigs, NULL);
1106	if (tsp)
1107		*tsp = evTimeSpec(tv);
1108	return (n);
1109}
1110#endif
1111