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source: rtems/cpukit/libnetworking/libc/res_send.c @ 39f13cb

4.104.115

Last change on this file since 39f13cb was 39f13cb, checked in by Ralf Corsepius <ralf.corsepius@…>, on 03/27/10 at 04:00:53
Add HAVE_STRINGS_H for better POSIX compliance.
Property mode set to `100644`
File size: 22.9 KB

Line
1	/*
2	* Copyright (c) 1985, 1989, 1993
3	* The Regents of the University of California. All rights reserved.
4	*
5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions
7	* are met:
8	* 1. Redistributions of source code must retain the above copyright
9	* notice, this list of conditions and the following disclaimer.
10	* 2. Redistributions in binary form must reproduce the above copyright
11	* notice, this list of conditions and the following disclaimer in the
12	* documentation and/or other materials provided with the distribution.
13	* 3. All advertising materials mentioning features or use of this software
14	* must display the following acknowledgement:
15	* This product includes software developed by the University of
16	* California, Berkeley and its contributors.
17	* 4. 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
34	/*
35	* Portions Copyright (c) 1993 by Digital Equipment Corporation.
36	*
37	* Permission to use, copy, modify, and distribute this software for any
38	* purpose with or without fee is hereby granted, provided that the above
39	* copyright notice and this permission notice appear in all copies, and that
40	* the name of Digital Equipment Corporation not be used in advertising or
41	* publicity pertaining to distribution of the document or software without
42	* specific, written prior permission.
43	*
44	* THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
45	* WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
46	* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
47	* CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
48	* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
49	* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
50	* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
51	* SOFTWARE.
52	*/
53
54	/*
55	* Portions Copyright (c) 1996 by Internet Software Consortium.
56	*
57	* Permission to use, copy, modify, and distribute this software for any
58	* purpose with or without fee is hereby granted, provided that the above
59	* copyright notice and this permission notice appear in all copies.
60	*
61	* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
62	* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
63	* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
64	* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
65	* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
66	* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
67	* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
68	* SOFTWARE.
69	*/
70
71	#if HAVE_CONFIG_H
72	#include "config.h"
73	#endif
74
75	/*
76	* Send query to name server and wait for reply.
77	*/
78
79	#include <sys/types.h>
80	#include <sys/param.h>
81	#include <sys/time.h>
82	#include <sys/socket.h>
83	#include <sys/uio.h>
84
85	#include <netinet/in.h>
86	#include <arpa/nameser.h>
87	#include <arpa/inet.h>
88
89	#include <errno.h>
90	#include <netdb.h>
91	#include <resolv.h>
92	#include <stdio.h>
93	#include <stdlib.h>
94	#include <string.h>
95	#ifdef HAVE_STRINGS_H
96	#include <strings.h>
97	#endif
98	#include <unistd.h>
99	#if !defined(__rtems__)
100	#include <poll.h>
101	#endif
102
103	/* RTEMS now has writev */
104	#define USE_WRITEV
105
106	#include "res_config.h"
107
108	#if !defined(__rtems__)
109
110	#ifdef NOPOLL /* libc_r doesn't wrap poll yet() */
111	static int use_poll = 0;
112	#else
113	static int use_poll = 1; /* adapt to poll() syscall availability */
114	/* 0 = not present, 1 = try it, 2 = exists */
115	#endif
116	#endif
117
118	static int s = -1; /* socket used for communications */
119	static int connected = 0; /* is the socket connected */
120	static int vc = 0; /* is the socket a virtual circuit? */
121	static res_send_qhook Qhook = NULL;
122	static res_send_rhook Rhook = NULL;
123
124
125	#define CAN_RECONNECT 1
126
127	#ifndef DEBUG
128	# define Dprint(cond, args) /empty/
129	# define DprintQ(cond, args, query, size) /empty/
130	# define Aerror(file, string, error, address) /empty/
131	# define Perror(file, string, error) /empty/
132	#else
133	# define Dprint(cond, args) if (cond) {fprintf args;} else {}
134	# define DprintQ(cond, args, query, size) if (cond) {\
135	fprintf args;\
136	__fp_nquery(query, size, stdout);\
137	} else {}
138	static void
139	Aerror(
140	FILE *file,
141	char *string,
142	int error,
143	struct sockaddr_in address)
144	{
145	int save = errno;
146
147	if (_res.options & RES_DEBUG) {
148	fprintf(file, "res_send: %s ([%s].%u): %s\n",
149	string,
150	inet_ntoa(address.sin_addr),
151	ntohs(address.sin_port),
152	strerror(error));
153	}
154	errno = save;
155	}
156	static void
157	Perror(
158	FILE *file,
159	char *string,
160	int error)
161	{
162	int save = errno;
163
164	if (_res.options & RES_DEBUG) {
165	fprintf(file, "res_send: %s: %s\n",
166	string, strerror(error));
167	}
168	errno = save;
169	}
170	#endif
171
172	void
173	res_send_setqhook(
174	res_send_qhook hook)
175	{
176
177	Qhook = hook;
178	}
179
180	void
181	res_send_setrhook(
182	res_send_rhook hook)
183	{
184
185	Rhook = hook;
186	}
187
188	/* int
189	* res_isourserver(ina)
190	* looks up "ina" in _res.ns_addr_list[]
191	* returns:
192	* 0 : not found
193	* >0 : found
194	* author:
195	* paul vixie, 29may94
196	*/
197	int
198	res_isourserver(
199	const struct sockaddr_in *inp)
200	{
201	struct sockaddr_in ina;
202	int ns, ret;
203
204	ina = *inp;
205	ret = 0;
206	for (ns = 0; ns < _res.nscount; ns++) {
207	const struct sockaddr_in *srv = &_res.nsaddr_list[ns];
208
209	if (srv->sin_family == ina.sin_family &&
210	srv->sin_port == ina.sin_port &&
211	(srv->sin_addr.s_addr == INADDR_ANY \|\|
212	srv->sin_addr.s_addr == ina.sin_addr.s_addr)) {
213	ret++;
214	break;
215	}
216	}
217	return (ret);
218	}
219
220	/* int
221	* res_nameinquery(name, type, class, buf, eom)
222	* look for (name,type,class) in the query section of packet (buf,eom)
223	* requires:
224	* buf + HFIXEDSZ <= eom
225	* returns:
226	* -1 : format error
227	* 0 : not found
228	* >0 : found
229	* author:
230	* paul vixie, 29may94
231	*/
232	int
233	res_nameinquery(
234	const char *name,
235	int type, int class,
236	const u_char buf, const u_char eom)
237	{
238	const u_char *cp = buf + HFIXEDSZ;
239	int qdcount = ntohs(((HEADER*)buf)->qdcount);
240
241	while (qdcount-- > 0) {
242	char tname[MAXDNAME+1];
243	int n, ttype, tclass;
244
245	n = dn_expand(buf, eom, cp, tname, sizeof tname);
246	if (n < 0)
247	return (-1);
248	cp += n;
249	if (cp + 2 * INT16SZ > eom)
250	return (-1);
251	ttype = ns_get16(cp); cp += INT16SZ;
252	tclass = ns_get16(cp); cp += INT16SZ;
253	if (ttype == type &&
254	tclass == class &&
255	strcasecmp(tname, name) == 0)
256	return (1);
257	}
258	return (0);
259	}
260
261	/* int
262	* res_queriesmatch(buf1, eom1, buf2, eom2)
263	* is there a 1:1 mapping of (name,type,class)
264	* in (buf1,eom1) and (buf2,eom2)?
265	* returns:
266	* -1 : format error
267	* 0 : not a 1:1 mapping
268	* >0 : is a 1:1 mapping
269	* author:
270	* paul vixie, 29may94
271	*/
272	int
273	res_queriesmatch(
274	const u_char buf1, const u_char eom1,
275	const u_char buf2, const u_char eom2)
276	{
277	const u_char *cp = buf1 + HFIXEDSZ;
278	int qdcount = ntohs(((HEADER*)buf1)->qdcount);
279
280	if (buf1 + HFIXEDSZ > eom1 \|\| buf2 + HFIXEDSZ > eom2)
281	return (-1);
282
283	/*
284	* Only header section present in replies to
285	* dynamic update packets.
286	*/
287	if ( (((HEADER *)buf1)->opcode == ns_o_update) &&
288	(((HEADER *)buf2)->opcode == ns_o_update) )
289	return (1);
290
291	if (qdcount != ntohs(((HEADER*)buf2)->qdcount))
292	return (0);
293	while (qdcount-- > 0) {
294	char tname[MAXDNAME+1];
295	int n, ttype, tclass;
296
297	n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
298	if (n < 0)
299	return (-1);
300	cp += n;
301	if (cp + 2 * INT16SZ > eom1)
302	return (-1);
303	ttype = ns_get16(cp); cp += INT16SZ;
304	tclass = ns_get16(cp); cp += INT16SZ;
305	if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
306	return (0);
307	}
308	return (1);
309	}
310
311	int
312	res_send(
313	const u_char *buf,
314	int buflen,
315	u_char *ans,
316	int anssiz)
317	{
318	HEADER hp = (HEADER ) buf;
319	HEADER anhp = (HEADER ) ans;
320	int gotsomewhere, connreset, terrno, try, v_circuit, resplen, ns, n;
321	u_int badns; /* XXX NSMAX can't exceed #/bits in this variable */
322
323	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
324	/* errno should have been set by res_init() in this case. */
325	return (-1);
326	}
327	if (anssiz < HFIXEDSZ) {
328	errno = EINVAL;
329	return (-1);
330	}
331	DprintQ((_res.options & RES_DEBUG) \|\| (_res.pfcode & RES_PRF_QUERY),
332	(stdout, ";; res_send()\n"), buf, buflen);
333	v_circuit = (_res.options & RES_USEVC) \|\| buflen > PACKETSZ;
334	gotsomewhere = 0;
335	connreset = 0;
336	terrno = ETIMEDOUT;
337	badns = 0;
338
339	/*
340	* Send request, RETRY times, or until successful
341	*/
342	for (try = 0; try < _res.retry; try++) {
343	for (ns = 0; ns < _res.nscount; ns++) {
344	struct sockaddr_in *nsap = &_res.nsaddr_list[ns];
345	same_ns:
346	if (badns & (1 << ns)) {
347	res_close();
348	goto next_ns;
349	}
350
351	if (Qhook) {
352	int done = 0, loops = 0;
353
354	do {
355	res_sendhookact act;
356
357	act = (*Qhook)(&nsap, &buf, &buflen,
358	ans, anssiz, &resplen);
359	switch (act) {
360	case res_goahead:
361	done = 1;
362	break;
363	case res_nextns:
364	res_close();
365	goto next_ns;
366	case res_done:
367	return (resplen);
368	case res_modified:
369	/* give the hook another try */
370	if (++loops < 42) /doug adams/
371	break;
372	/FALLTHROUGH/
373	case res_error:
374	/FALLTHROUGH/
375	default:
376	return (-1);
377	}
378	} while (!done);
379	}
380
381	Dprint(_res.options & RES_DEBUG,
382	(stdout, ";; Querying server (# %d) address = %s\n",
383	ns + 1, inet_ntoa(nsap->sin_addr)));
384
385	if (v_circuit) {
386	int truncated;
387	#if defined(USE_WRITEV)
388	struct iovec iov[2];
389	#endif
390	u_short len;
391	u_char *cp;
392
393	/*
394	* Use virtual circuit;
395	* at most one attempt per server.
396	*/
397	try = _res.retry;
398	truncated = 0;
399	if (s < 0 \|\| !vc \|\| hp->opcode == ns_o_update) {
400	if (s >= 0)
401	res_close();
402
403	s = socket(PF_INET, SOCK_STREAM, 0);
404	if (s < 0) {
405	terrno = errno;
406	Perror(stderr, "socket(vc)", errno);
407	return (-1);
408	}
409	errno = 0;
410	if (connect(s, (struct sockaddr *)nsap,
411	sizeof *nsap) < 0) {
412	terrno = errno;
413	Aerror(stderr, "connect/vc",
414	errno, *nsap);
415	badns \|= (1 << ns);
416	res_close();
417	goto next_ns;
418	}
419	vc = 1;
420	}
421	/*
422	* Send length & message
423	*/
424	putshort((u_short)buflen, (u_char*)&len);
425	#if defined(USE_WRITEV)
426	iov[0].iov_base = (caddr_t)&len;
427	iov[0].iov_len = INT16SZ;
428	iov[1].iov_base = (caddr_t)buf;
429	iov[1].iov_len = buflen;
430	if (writev(s, iov, 2) != (INT16SZ + buflen)) {
431	#else
432	/*
433	* RTEMS doesn't have writev (yet)
434	*/
435	if ((write (s, &len, INT16SZ) != INT16SZ)
436	\|\| (write (s, buf, buflen) != buflen)) {
437	#endif
438	terrno = errno;
439	Perror(stderr, "write failed", errno);
440	badns \|= (1 << ns);
441	res_close();
442	goto next_ns;
443	}
444	/*
445	* Receive length & response
446	*/
447	read_len:
448	cp = ans;
449	len = INT16SZ;
450	while ((n = read(s, (char *)cp, (int)len)) > 0) {
451	cp += n;
452	if ((len -= n) <= 0)
453	break;
454	}
455	if (n <= 0) {
456	terrno = errno;
457	Perror(stderr, "read failed", errno);
458	res_close();
459	/*
460	* A long running process might get its TCP
461	* connection reset if the remote server was
462	* restarted. Requery the server instead of
463	* trying a new one. When there is only one
464	* server, this means that a query might work
465	* instead of failing. We only allow one reset
466	* per query to prevent looping.
467	*/
468	if (terrno == ECONNRESET && !connreset) {
469	connreset = 1;
470	res_close();
471	goto same_ns;
472	}
473	res_close();
474	goto next_ns;
475	}
476	resplen = ns_get16(ans);
477	if (resplen > anssiz) {
478	Dprint(_res.options & RES_DEBUG,
479	(stdout, ";; response truncated\n")
480	);
481	truncated = 1;
482	len = anssiz;
483	} else
484	len = resplen;
485	if (len < HFIXEDSZ) {
486	/*
487	* Undersized message.
488	*/
489	Dprint(_res.options & RES_DEBUG,
490	(stdout, ";; undersized: %d\n", len));
491	terrno = EMSGSIZE;
492	badns \|= (1 << ns);
493	res_close();
494	goto next_ns;
495	}
496	cp = ans;
497	while (len != 0 &&
498	(n = read(s, (char *)cp, (int)len)) > 0) {
499	cp += n;
500	len -= n;
501	}
502	if (n <= 0) {
503	terrno = errno;
504	Perror(stderr, "read(vc)", errno);
505	res_close();
506	goto next_ns;
507	}
508	if (truncated) {
509	/*
510	* Flush rest of answer
511	* so connection stays in synch.
512	*/
513	anhp->tc = 1;
514	len = resplen - anssiz;
515	while (len != 0) {
516	char junk[PACKETSZ];
517
518	n = (len > sizeof(junk)
519	? sizeof(junk)
520	: len);
521	if ((n = read(s, junk, n)) > 0)
522	len -= n;
523	else
524	break;
525	}
526	}
527	/*
528	* The calling applicating has bailed out of
529	* a previous call and failed to arrange to have
530	* the circuit closed or the server has got
531	* itself confused. Anyway drop the packet and
532	* wait for the correct one.
533	*/
534	if (hp->id != anhp->id) {
535	DprintQ((_res.options & RES_DEBUG) \|\|
536	(_res.pfcode & RES_PRF_REPLY),
537	(stdout, ";; old answer (unexpected):\n"),
538	ans, (resplen>anssiz)?anssiz:resplen);
539	goto read_len;
540	}
541	} else {
542	/*
543	* Use datagrams.
544	*/
545	#ifndef NOPOLL
546	struct pollfd pfd;
547	int msec;
548	#endif
549	struct timeval timeout;
550	#ifndef NOSELECT
551	fd_set dsmask, *dsmaskp;
552	int dsmasklen;
553	#endif
554	struct sockaddr_in from;
555	socklen_t fromlen;
556
557	if ((s < 0) \|\| vc) {
558	if (vc)
559	res_close();
560	s = socket(PF_INET, SOCK_DGRAM, 0);
561	if (s < 0) {
562	#ifndef CAN_RECONNECT
563	bad_dg_sock:
564	#endif
565	terrno = errno;
566	Perror(stderr, "socket(dg)", errno);
567	return (-1);
568	}
569	connected = 0;
570	}
571	#ifndef CANNOT_CONNECT_DGRAM
572	/*
573	* On a 4.3BSD+ machine (client and server,
574	* actually), sending to a nameserver datagram
575	* port with no nameserver will cause an
576	* ICMP port unreachable message to be returned.
577	* If our datagram socket is "connected" to the
578	* server, we get an ECONNREFUSED error on the next
579	* socket operation, and select returns if the
580	* error message is received. We can thus detect
581	* the absence of a nameserver without timing out.
582	* If we have sent queries to at least two servers,
583	* however, we don't want to remain connected,
584	* as we wish to receive answers from the first
585	* server to respond.
586	*/
587	if (_res.nscount == 1 \|\| (try == 0 && ns == 0)) {
588	/*
589	* Connect only if we are sure we won't
590	* receive a response from another server.
591	*/
592	if (!connected) {
593	if (connect(s, (struct sockaddr *)nsap,
594	sizeof *nsap
595	) < 0) {
596	Aerror(stderr,
597	"connect(dg)",
598	errno, *nsap);
599	badns \|= (1 << ns);
600	res_close();
601	goto next_ns;
602	}
603	connected = 1;
604	}
605	if (send(s, (char*)buf, buflen, 0) != buflen) {
606	Perror(stderr, "send", errno);
607	badns \|= (1 << ns);
608	res_close();
609	goto next_ns;
610	}
611	} else {
612	/*
613	* Disconnect if we want to listen
614	* for responses from more than one server.
615	*/
616	if (connected) {
617	#ifdef CAN_RECONNECT
618	struct sockaddr_in no_addr;
619
620	no_addr.sin_family = AF_INET;
621	no_addr.sin_addr.s_addr = INADDR_ANY;
622	no_addr.sin_port = 0;
623	(void) connect(s,
624	(struct sockaddr *)
625	&no_addr,
626	sizeof no_addr);
627	#else
628	int s1 = socket(PF_INET, SOCK_DGRAM,0);
629	if (s1 < 0)
630	goto bad_dg_sock;
631	(void) dup2(s1, s);
632	(void) close(s1);
633	Dprint(_res.options & RES_DEBUG,
634	(stdout, ";; new DG socket\n"))
635	#endif /* CAN_RECONNECT */
636	connected = 0;
637	errno = 0;
638	}
639	#endif /* !CANNOT_CONNECT_DGRAM */
640	if (sendto(s, (char*)buf, buflen, 0,
641	(struct sockaddr *)nsap,
642	sizeof *nsap)
643	!= buflen) {
644	Aerror(stderr, "sendto", errno, *nsap);
645	badns \|= (1 << ns);
646	res_close();
647	goto next_ns;
648	}
649	#ifndef CANNOT_CONNECT_DGRAM
650	}
651	#endif /* !CANNOT_CONNECT_DGRAM */
652
653	/*
654	* Wait for reply
655	*/
656	#ifndef NOPOLL
657	othersyscall:
658	if (use_poll) {
659	msec = (_res.retrans << try) * 1000;
660	if (try > 0)
661	msec /= _res.nscount;
662	if (msec <= 0)
663	msec = 1000;
664	} else {
665	#endif
666	timeout.tv_sec = (_res.retrans << try);
667	if (try > 0)
668	timeout.tv_sec /= _res.nscount;
669	if ((long) timeout.tv_sec <= 0)
670	timeout.tv_sec = 1;
671	timeout.tv_usec = 0;
672	#ifndef NOPOLL
673	}
674	#endif
675	wait:
676	if (s < 0) {
677	Perror(stderr, "s out-of-bounds", EMFILE);
678	res_close();
679	goto next_ns;
680	}
681	#ifndef NOPOLL
682	if (use_poll) {
683	struct sigaction sa, osa;
684	int sigsys_installed = 0;
685
686	pfd.fd = s;
687	pfd.events = POLLIN;
688	if (use_poll == 1) {
689	bzero(&sa, sizeof(sa));
690	sa.sa_handler = SIG_IGN;
691	if (sigaction(SIGSYS, &sa, &osa) >= 0)
692	sigsys_installed = 1;
693	}
694	n = poll(&pfd, 1, msec);
695	if (sigsys_installed == 1) {
696	int oerrno = errno;
697	sigaction(SIGSYS, &osa, NULL);
698	errno = oerrno;
699	}
700	/* XXX why does nosys() return EINVAL? */
701	if (n < 0 && (errno == ENOSYS \|\|
702	errno == EINVAL)) {
703	use_poll = 0;
704	goto othersyscall;
705	} else if (use_poll == 1)
706	use_poll = 2;
707	if (n < 0) {
708	if (errno == EINTR)
709	goto wait;
710	Perror(stderr, "poll", errno);
711	res_close();
712	goto next_ns;
713	}
714	} else {
715	#endif
716	#ifndef NOSELECT
717	dsmasklen = howmany(s + 1, NFDBITS) *
718	sizeof(fd_mask);
719	if (dsmasklen > sizeof(fd_set)) {
720	dsmaskp = (fd_set *)malloc(dsmasklen);
721	if (dsmaskp == NULL) {
722	res_close();
723	goto next_ns;
724	}
725	} else
726	dsmaskp = &dsmask;
727	/* only zero what we need */
728	bzero((char *)dsmaskp, dsmasklen);
729	FD_SET(s, dsmaskp);
730	n = select(s + 1, dsmaskp, (fd_set *)NULL,
731	(fd_set *)NULL, &timeout);
732	if (dsmaskp != &dsmask)
733	free(dsmaskp);
734	if (n < 0) {
735	if (errno == EINTR)
736	goto wait;
737	Perror(stderr, "select", errno);
738	res_close();
739	goto next_ns;
740	}
741	#endif
742	#ifndef NOPOLL
743	}
744	#endif
745
746	#ifdef NOSELECT
747	setsockopt (s, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof timeout);
748	#else
749	if (n == 0) {
750	/*
751	* timeout
752	*/
753	Dprint(_res.options & RES_DEBUG,
754	(stdout, ";; timeout\n"));
755	gotsomewhere = 1;
756	res_close();
757	goto next_ns;
758	}
759	#endif
760	errno = 0;
761	fromlen = sizeof(struct sockaddr_in);
762	resplen = recvfrom(s, (char*)ans, anssiz, 0,
763	(struct sockaddr *)&from, &fromlen);
764	if (resplen <= 0) {
765	#ifdef NOSELECT
766	if (errno == ETIMEDOUT) {
767	Dprint(_res.options & RES_DEBUG,
768	(stdout, ";; timeout\n"));
769	gotsomewhere = 1;
770	res_close();
771	goto next_ns;
772	}
773	#endif
774	Perror(stderr, "recvfrom", errno);
775	res_close();
776	goto next_ns;
777	}
778	gotsomewhere = 1;
779	if (resplen < HFIXEDSZ) {
780	/*
781	* Undersized message.
782	*/
783	Dprint(_res.options & RES_DEBUG,
784	(stdout, ";; undersized: %d\n",
785	resplen));
786	terrno = EMSGSIZE;
787	badns \|= (1 << ns);
788	res_close();
789	goto next_ns;
790	}
791	if (hp->id != anhp->id) {
792	/*
793	* response from old query, ignore it.
794	* XXX - potential security hazard could
795	* be detected here.
796	*/
797	DprintQ((_res.options & RES_DEBUG) \|\|
798	(_res.pfcode & RES_PRF_REPLY),
799	(stdout, ";; old answer:\n"),
800	ans, (resplen>anssiz)?anssiz:resplen);
801	goto wait;
802	}
803	#ifdef CHECK_SRVR_ADDR
804	if (!(_res.options & RES_INSECURE1) &&
805	!res_isourserver(&from)) {
806	/*
807	* response from wrong server? ignore it.
808	* XXX - potential security hazard could
809	* be detected here.
810	*/
811	DprintQ((_res.options & RES_DEBUG) \|\|
812	(_res.pfcode & RES_PRF_REPLY),
813	(stdout, ";; not our server:\n"),
814	ans, (resplen>anssiz)?anssiz:resplen);
815	goto wait;
816	}
817	#endif
818	if (!(_res.options & RES_INSECURE2) &&
819	!res_queriesmatch(buf, buf + buflen,
820	ans, ans + anssiz)) {
821	/*
822	* response contains wrong query? ignore it.
823	* XXX - potential security hazard could
824	* be detected here.
825	*/
826	DprintQ((_res.options & RES_DEBUG) \|\|
827	(_res.pfcode & RES_PRF_REPLY),
828	(stdout, ";; wrong query name:\n"),
829	ans, (resplen>anssiz)?anssiz:resplen);
830	goto wait;
831	}
832	if (anhp->rcode == SERVFAIL \|\|
833	anhp->rcode == NOTIMP \|\|
834	anhp->rcode == REFUSED) {
835	DprintQ(_res.options & RES_DEBUG,
836	(stdout, "server rejected query:\n"),
837	ans, (resplen>anssiz)?anssiz:resplen);
838	badns \|= (1 << ns);
839	res_close();
840	/* don't retry if called from dig */
841	if (!_res.pfcode)
842	goto next_ns;
843	}
844	if (!(_res.options & RES_IGNTC) && anhp->tc) {
845	/*
846	* get rest of answer;
847	* use TCP with same server.
848	*/
849	Dprint(_res.options & RES_DEBUG,
850	(stdout, ";; truncated answer\n"));
851	v_circuit = 1;
852	res_close();
853	goto same_ns;
854	}
855	} /if vc/dg/
856	Dprint((_res.options & RES_DEBUG) \|\|
857	((_res.pfcode & RES_PRF_REPLY) &&
858	(_res.pfcode & RES_PRF_HEAD1)),
859	(stdout, ";; got answer:\n"));
860	DprintQ((_res.options & RES_DEBUG) \|\|
861	(_res.pfcode & RES_PRF_REPLY),
862	(stdout, "%s", ""),
863	ans, (resplen>anssiz)?anssiz:resplen);
864	/*
865	* If using virtual circuits, we assume that the first server
866	* is preferred over the rest (i.e. it is on the local
867	* machine) and only keep that one open.
868	* If we have temporarily opened a virtual circuit,
869	* or if we haven't been asked to keep a socket open,
870	* close the socket.
871	*/
872	if ((v_circuit && (!(_res.options & RES_USEVC) \|\| ns != 0)) \|\|
873	!(_res.options & RES_STAYOPEN)) {
874	res_close();
875	}
876	if (Rhook) {
877	int done = 0, loops = 0;
878
879	do {
880	res_sendhookact act;
881
882	act = (*Rhook)(nsap, buf, buflen,
883	ans, anssiz, &resplen);
884	switch (act) {
885	case res_goahead:
886	case res_done:
887	done = 1;
888	break;
889	case res_nextns:
890	res_close();
891	goto next_ns;
892	case res_modified:
893	/* give the hook another try */
894	if (++loops < 42) /doug adams/
895	break;
896	/FALLTHROUGH/
897	case res_error:
898	/FALLTHROUGH/
899	default:
900	return (-1);
901	}
902	} while (!done);
903
904	}
905	return (resplen);
906	next_ns: ;
907	} /foreach ns/
908	} /foreach retry/
909	res_close();
910	if (!v_circuit) {
911	if (!gotsomewhere)
912	errno = ECONNREFUSED; /* no nameservers found */
913	else
914	errno = ETIMEDOUT; /* no answer obtained */
915	} else
916	errno = terrno;
917	return (-1);
918	}
919
920	/*
921	* This routine is for closing the socket if a virtual circuit is used and
922	* the program wants to close it. This provides support for endhostent()
923	* which expects to close the socket.
924	*
925	* This routine is not expected to be user visible.
926	*/
927	void
928	res_close(void)
929	{
930	if (s >= 0) {
931	(void) close(s);
932	s = -1;
933	connected = 0;
934	vc = 0;
935	}
936	}

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