1 /*
2 * ++Copyright++ 1985, 1989, 1993
3 * -
4 * Copyright (c) 1985, 1989, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by the University of
18 * California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
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 * --Copyright--
54 */
55
56 #if defined(LIBC_SCCS) && !defined(lint)
57 static char sccsid[] = "@(#)res_send.c 8.1 (Berkeley) 6/4/93";
58 static char rcsid[] = "$Id: res_send.c,v 8.14 1998/04/07 04:59:46 vixie Exp $";
59 #endif /* LIBC_SCCS and not lint */
60
61 /* change this to "0"
62 * if you talk to a lot
63 * of multi-homed SunOS
64 * ("broken") name servers.
65 */
66 #define CHECK_SRVR_ADDR 1 /* XXX - should be in options.h */
67
68 /*
69 * Send query to name server and wait for reply.
70 */
71
72 #include <sys/types.h>
73 #include <sys/param.h>
74 #include <sys/time.h>
75 #include <sys/socket.h>
76 #include <sys/uio.h>
77 #include <netinet/in.h>
78 #include <arpa/nameser.h>
79 #include <arpa/inet.h>
80
81 #include <stdio.h>
82 #include <netdb.h>
83 #include <errno.h>
84 #include <resolv.h>
85 #if defined(BSD) && (BSD >= 199306)
86 # include <stdlib.h>
87 # include <string.h>
88 # include <unistd.h>
89 #else
90 # include "../conf/portability.h"
91 #endif
92
93 #if defined(USE_OPTIONS_H)
94 # include <../conf/options.h>
95 #endif
96
97 static int s = -1; /* socket used for communications */
98 static int connected = 0; /* is the socket connected */
99 static int vc = 0; /* is the socket a virtual ciruit? */
100
101 #ifndef FD_SET
102 /* XXX - should be in portability.h */
103 #define NFDBITS 32
104 #define FD_SETSIZE 32
105 #define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
106 #define FD_CLR(n, p) ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
107 #define FD_ISSET(n, p) ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
108 #define FD_ZERO(p) bzero((char *)(p), sizeof(*(p)))
109 #endif
110
111 /* XXX - this should be done in portability.h */
112 #if (defined(BSD) && (BSD >= 199103)) || defined(linux)
113 # define CAN_RECONNECT 1
114 #else
115 # define CAN_RECONNECT 0
116 #endif
117
118 #ifndef DEBUG
119 # define Dprint(cond, args) /*empty*/
120 # define DprintQ(cond, args, query, size) /*empty*/
121 # define Aerror(file, string, error, address) /*empty*/
122 # define Perror(file, string, error) /*empty*/
123 #else
124 # define Dprint(cond, args) if (cond) {fprintf args;} else {}
125 # define DprintQ(cond, args, query, size) if (cond) {\
126 fprintf args;\
127 __fp_nquery(query, size, stdout);\
128 } else {}
129 static void
Aerror(file,string,error,address)130 Aerror(file, string, error, address)
131 FILE *file;
132 char *string;
133 int error;
134 struct sockaddr_in address;
135 {
136 int save = errno;
137
138 if (_res.options & RES_DEBUG) {
139 fprintf(file, "res_send: %s ([%s].%u): %s\n",
140 string,
141 inet_ntoa(address.sin_addr),
142 ntohs(address.sin_port),
143 strerror(error));
144 }
145 errno = save;
146 }
147 static void
Perror(file,string,error)148 Perror(file, string, error)
149 FILE *file;
150 char *string;
151 int error;
152 {
153 int save = errno;
154
155 if (_res.options & RES_DEBUG) {
156 fprintf(file, "res_send: %s: %s\n",
157 string, strerror(error));
158 }
159 errno = save;
160 }
161 #endif
162
163 static res_send_qhook Qhook = NULL;
164 static res_send_rhook Rhook = NULL;
165
166 void
res_send_setqhook(hook)167 res_send_setqhook(hook)
168 res_send_qhook hook;
169 {
170
171 Qhook = hook;
172 }
173
174 void
res_send_setrhook(hook)175 res_send_setrhook(hook)
176 res_send_rhook hook;
177 {
178
179 Rhook = hook;
180 }
181
182 /* int
183 * res_isourserver(ina)
184 * looks up "ina" in _res.ns_addr_list[]
185 * returns:
186 * 0 : not found
187 * >0 : found
188 * author:
189 * paul vixie, 29may94
190 */
191 int
res_isourserver(inp)192 res_isourserver(inp)
193 const struct sockaddr_in *inp;
194 {
195 struct sockaddr_in ina;
196 register int ns, ret;
197
198 ina = *inp;
199 ret = 0;
200 for (ns = 0; ns < _res.nscount; ns++) {
201 register const struct sockaddr_in *srv = &_res.nsaddr_list[ns];
202
203 if (srv->sin_family == ina.sin_family &&
204 srv->sin_port == ina.sin_port &&
205 (srv->sin_addr.s_addr == INADDR_ANY ||
206 srv->sin_addr.s_addr == ina.sin_addr.s_addr)) {
207 ret++;
208 break;
209 }
210 }
211 return (ret);
212 }
213
214 /* int
215 * res_nameinquery(name, type, class, buf, eom)
216 * look for (name,type,class) in the query section of packet (buf,eom)
217 * requires:
218 * buf + HFIXESDZ <= eom
219 * returns:
220 * -1 : format error
221 * 0 : not found
222 * >0 : found
223 * author:
224 * paul vixie, 29may94
225 */
226 int
res_nameinquery(name,type,class,buf,eom)227 res_nameinquery(name, type, class, buf, eom)
228 const char *name;
229 register int type, class;
230 const u_char *buf, *eom;
231 {
232 register const u_char *cp = buf + HFIXEDSZ;
233 int qdcount = ntohs(((HEADER*)buf)->qdcount);
234
235 while (qdcount-- > 0) {
236 char tname[MAXDNAME+1];
237 register int n, ttype, tclass;
238
239 n = dn_expand(buf, eom, cp, tname, sizeof tname);
240 if (n < 0)
241 return (-1);
242 cp += n;
243 if (cp + 2 * INT16SZ > eom)
244 return (-1);
245 ttype = _getshort(cp); cp += INT16SZ;
246 tclass = _getshort(cp); cp += INT16SZ;
247 if (ttype == type &&
248 tclass == class &&
249 strcasecmp(tname, name) == 0)
250 return (1);
251 }
252 return (0);
253 }
254
255 /* int
256 * res_queriesmatch(buf1, eom1, buf2, eom2)
257 * is there a 1:1 mapping of (name,type,class)
258 * in (buf1,eom1) and (buf2,eom2)?
259 * returns:
260 * -1 : format error
261 * 0 : not a 1:1 mapping
262 * >0 : is a 1:1 mapping
263 * author:
264 * paul vixie, 29may94
265 */
266 int
res_queriesmatch(buf1,eom1,buf2,eom2)267 res_queriesmatch(buf1, eom1, buf2, eom2)
268 const u_char *buf1, *eom1;
269 const u_char *buf2, *eom2;
270 {
271 register const u_char *cp = buf1 + HFIXEDSZ;
272 int qdcount = ntohs(((HEADER*)buf1)->qdcount);
273
274 if (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2)
275 return (-1);
276
277 if (qdcount != ntohs(((HEADER*)buf2)->qdcount))
278 return (0);
279 while (qdcount-- > 0) {
280 char tname[MAXDNAME+1];
281 register int n, ttype, tclass;
282
283 n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
284 if (n < 0)
285 return (-1);
286 cp += n;
287 if (cp + 2 * INT16SZ > eom1)
288 return (-1);
289 ttype = _getshort(cp); cp += INT16SZ;
290 tclass = _getshort(cp); cp += INT16SZ;
291 if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
292 return (0);
293 }
294 return (1);
295 }
296
297 int
res_send(buf,buflen,ans,anssiz)298 res_send(buf, buflen, ans, anssiz)
299 const u_char *buf;
300 int buflen;
301 u_char *ans;
302 int anssiz;
303 {
304 HEADER *hp = (HEADER *) buf;
305 HEADER *anhp = (HEADER *) ans;
306 int gotsomewhere, connreset, terrno, try, v_circuit, resplen, ns;
307 register int n;
308 u_int badns; /* XXX NSMAX can't exceed #/bits in this var */
309
310 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
311 /* errno should have been set by res_init() in this case. */
312 return (-1);
313 }
314 if (anssiz < HFIXEDSZ) {
315 errno = EINVAL;
316 return (-1);
317 }
318 DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_QUERY),
319 (stdout, ";; res_send()\n"), buf, buflen);
320 v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
321 gotsomewhere = 0;
322 connreset = 0;
323 terrno = ETIMEDOUT;
324 badns = 0;
325
326 /*
327 * Send request, RETRY times, or until successful
328 */
329 for (try = 0; try < _res.retry; try++) {
330 for (ns = 0; ns < _res.nscount; ns++) {
331 struct sockaddr_in *nsap = &_res.nsaddr_list[ns];
332 same_ns:
333 if (badns & (1 << ns)) {
334 res_close();
335 goto next_ns;
336 }
337
338 if (Qhook) {
339 int done = 0, loops = 0;
340
341 do {
342 res_sendhookact act;
343
344 act = (*Qhook)(&nsap, &buf, &buflen,
345 ans, anssiz, &resplen);
346 switch (act) {
347 case res_goahead:
348 done = 1;
349 break;
350 case res_nextns:
351 res_close();
352 goto next_ns;
353 case res_done:
354 return (resplen);
355 case res_modified:
356 /* give the hook another try */
357 if (++loops < 42) /*doug adams*/
358 break;
359 /*FALLTHROUGH*/
360 case res_error:
361 /*FALLTHROUGH*/
362 default:
363 return (-1);
364 }
365 } while (!done);
366 }
367
368 Dprint(_res.options & RES_DEBUG,
369 (stdout, ";; Querying server (# %d) address = %s\n",
370 ns + 1, inet_ntoa(nsap->sin_addr)));
371
372 if (v_circuit) {
373 int truncated;
374 struct iovec iov[2];
375 u_short len;
376 u_char *cp;
377
378 /*
379 * Use virtual circuit;
380 * at most one attempt per server.
381 */
382 try = _res.retry;
383 truncated = 0;
384 if ((s < 0) || (!vc)) {
385 if (s >= 0)
386 res_close();
387
388 s = socket(PF_INET, SOCK_STREAM, 0);
389 if (s < 0) {
390 terrno = errno;
391 Perror(stderr, "socket(vc)", errno);
392 return (-1);
393 }
394 errno = 0;
395 if (connect(s, (struct sockaddr *)nsap,
396 sizeof(struct sockaddr)) < 0) {
397 terrno = errno;
398 Aerror(stderr, "connect/vc",
399 errno, *nsap);
400 badns |= (1 << ns);
401 res_close();
402 goto next_ns;
403 }
404 vc = 1;
405 }
406 /*
407 * Send length & message
408 */
409 putshort((u_short)buflen, (u_char*)&len);
410 iov[0].iov_base = (caddr_t)&len;
411 iov[0].iov_len = INT16SZ;
412 iov[1].iov_base = (caddr_t)buf;
413 iov[1].iov_len = buflen;
414 if (writev(s, iov, 2) != (INT16SZ + buflen)) {
415 terrno = errno;
416 Perror(stderr, "write failed", errno);
417 badns |= (1 << ns);
418 res_close();
419 goto next_ns;
420 }
421 /*
422 * Receive length & response
423 */
424 read_len:
425 cp = ans;
426 len = INT16SZ;
427 while ((n = read(s, (char *)cp, (int)len)) > 0) {
428 cp += n;
429 if ((len -= n) <= 0)
430 break;
431 }
432 if (n <= 0) {
433 terrno = errno;
434 Perror(stderr, "read failed", errno);
435 res_close();
436 /*
437 * A long running process might get its TCP
438 * connection reset if the remote server was
439 * restarted. Requery the server instead of
440 * trying a new one. When there is only one
441 * server, this means that a query might work
442 * instead of failing. We only allow one reset
443 * per query to prevent looping.
444 */
445 if (terrno == ECONNRESET && !connreset) {
446 connreset = 1;
447 res_close();
448 goto same_ns;
449 }
450 res_close();
451 goto next_ns;
452 }
453 resplen = _getshort(ans);
454 if (resplen > anssiz) {
455 Dprint(_res.options & RES_DEBUG,
456 (stdout, ";; response truncated\n")
457 );
458 truncated = 1;
459 len = anssiz;
460 } else
461 len = resplen;
462 if (len < HFIXEDSZ) {
463 /*
464 * Undersized message.
465 */
466 Dprint(_res.options & RES_DEBUG,
467 (stdout, ";; undersized: %d\n", len));
468 terrno = EMSGSIZE;
469 badns |= (1 << ns);
470 res_close();
471 goto next_ns;
472 }
473 cp = ans;
474 while (len != 0 &&
475 (n = read(s, (char *)cp, (int)len)) > 0) {
476 cp += n;
477 len -= n;
478 }
479 if (n <= 0) {
480 terrno = errno;
481 Perror(stderr, "read(vc)", errno);
482 res_close();
483 goto next_ns;
484 }
485 if (truncated) {
486 /*
487 * Flush rest of answer
488 * so connection stays in synch.
489 */
490 anhp->tc = 1;
491 len = resplen - anssiz;
492 while (len != 0) {
493 char junk[PACKETSZ];
494
495 n = (len > sizeof(junk)
496 ? sizeof(junk)
497 : len);
498 if ((n = read(s, junk, n)) > 0)
499 len -= n;
500 else
501 break;
502 }
503 }
504 /*
505 * The calling applicating has bailed out of
506 * a previous call and failed to arrange to have
507 * the circuit closed or the server has got
508 * itself confused. Anyway drop the packet and
509 * wait for the correct one.
510 */
511 if (hp->id != anhp->id) {
512 DprintQ((_res.options & RES_DEBUG) ||
513 (_res.pfcode & RES_PRF_REPLY),
514 (stdout, ";; old answer (unexpected):\n"),
515 ans, (resplen>anssiz)?anssiz:resplen);
516 goto read_len;
517 }
518 } else {
519 /*
520 * Use datagrams.
521 */
522 struct timeval timeout;
523 fd_set dsmask;
524 struct sockaddr_in from;
525 int fromlen;
526
527 if ((s < 0) || vc) {
528 if (vc)
529 res_close();
530 s = socket(PF_INET, SOCK_DGRAM, 0);
531 if (s < 0) {
532 #if !CAN_RECONNECT
533 bad_dg_sock:
534 #endif
535 terrno = errno;
536 Perror(stderr, "socket(dg)", errno);
537 return (-1);
538 }
539 connected = 0;
540 }
541 /*
542 * On a 4.3BSD+ machine (client and server,
543 * actually), sending to a nameserver datagram
544 * port with no nameserver will cause an
545 * ICMP port unreachable message to be returned.
546 * If our datagram socket is "connected" to the
547 * server, we get an ECONNREFUSED error on the next
548 * socket operation, and select returns if the
549 * error message is received. We can thus detect
550 * the absence of a nameserver without timing out.
551 * If we have sent queries to at least two servers,
552 * however, we don't want to remain connected,
553 * as we wish to receive answers from the first
554 * server to respond.
555 */
556 if (_res.nscount == 1 || (try == 0 && ns == 0)) {
557 /*
558 * Connect only if we are sure we won't
559 * receive a response from another server.
560 */
561 if (!connected) {
562 if (connect(s, (struct sockaddr *)nsap,
563 sizeof(struct sockaddr)
564 ) < 0) {
565 Aerror(stderr,
566 "connect(dg)",
567 errno, *nsap);
568 badns |= (1 << ns);
569 res_close();
570 goto next_ns;
571 }
572 connected = 1;
573 }
574 if (send(s, (char*)buf, buflen, 0) != buflen) {
575 Perror(stderr, "send", errno);
576 badns |= (1 << ns);
577 res_close();
578 goto next_ns;
579 }
580 } else {
581 /*
582 * Disconnect if we want to listen
583 * for responses from more than one server.
584 */
585 if (connected) {
586 #if CAN_RECONNECT
587 struct sockaddr_in no_addr;
588
589 no_addr.sin_family = AF_INET;
590 no_addr.sin_addr.s_addr = INADDR_ANY;
591 no_addr.sin_port = 0;
592 (void) connect(s,
593 (struct sockaddr *)
594 &no_addr,
595 sizeof(no_addr));
596 #else
597 int s1 = socket(PF_INET, SOCK_DGRAM,0);
598 if (s1 < 0)
599 goto bad_dg_sock;
600 (void) dup2(s1, s);
601 (void) close(s1);
602 Dprint(_res.options & RES_DEBUG,
603 (stdout, ";; new DG socket\n"))
604 #endif
605 connected = 0;
606 errno = 0;
607 }
608 if (sendto(s, (char*)buf, buflen, 0,
609 (struct sockaddr *)nsap,
610 sizeof(struct sockaddr))
611 != buflen) {
612 Aerror(stderr, "sendto", errno, *nsap);
613 badns |= (1 << ns);
614 res_close();
615 goto next_ns;
616 }
617 }
618
619 /*
620 * Wait for reply
621 */
622 timeout.tv_sec = (_res.retrans << try);
623 if (try > 0)
624 timeout.tv_sec /= _res.nscount;
625 if ((long) timeout.tv_sec <= 0)
626 timeout.tv_sec = 1;
627 timeout.tv_usec = 0;
628 wait:
629 if (s < 0 || s >= FD_SETSIZE) {
630 Perror(stderr, "s out-of-bounds", EMFILE);
631 res_close();
632 goto next_ns;
633 }
634 FD_ZERO(&dsmask);
635 FD_SET(s, &dsmask);
636 n = select(s+1, &dsmask, (fd_set *)NULL,
637 (fd_set *)NULL, &timeout);
638 if (n < 0) {
639 if (errno == EINTR)
640 goto wait;
641 Perror(stderr, "select", errno);
642 res_close();
643 goto next_ns;
644 }
645 if (n == 0) {
646 /*
647 * timeout
648 */
649 Dprint(_res.options & RES_DEBUG,
650 (stdout, ";; timeout\n"));
651 gotsomewhere = 1;
652 res_close();
653 goto next_ns;
654 }
655 errno = 0;
656 fromlen = sizeof(struct sockaddr_in);
657 resplen = recvfrom(s, (char*)ans, anssiz, 0,
658 (struct sockaddr *)&from, &fromlen);
659 if (resplen <= 0) {
660 Perror(stderr, "recvfrom", errno);
661 res_close();
662 goto next_ns;
663 }
664 gotsomewhere = 1;
665 if (resplen < HFIXEDSZ) {
666 /*
667 * Undersized message.
668 */
669 Dprint(_res.options & RES_DEBUG,
670 (stdout, ";; undersized: %d\n",
671 resplen));
672 terrno = EMSGSIZE;
673 badns |= (1 << ns);
674 res_close();
675 goto next_ns;
676 }
677 if (hp->id != anhp->id) {
678 /*
679 * response from old query, ignore it.
680 * XXX - potential security hazard could
681 * be detected here.
682 */
683 DprintQ((_res.options & RES_DEBUG) ||
684 (_res.pfcode & RES_PRF_REPLY),
685 (stdout, ";; old answer:\n"),
686 ans, (resplen>anssiz)?anssiz:resplen);
687 goto wait;
688 }
689 #if CHECK_SRVR_ADDR
690 if (!(_res.options & RES_INSECURE1) &&
691 !res_isourserver(&from)) {
692 /*
693 * response from wrong server? ignore it.
694 * XXX - potential security hazard could
695 * be detected here.
696 */
697 DprintQ((_res.options & RES_DEBUG) ||
698 (_res.pfcode & RES_PRF_REPLY),
699 (stdout, ";; not our server:\n"),
700 ans, (resplen>anssiz)?anssiz:resplen);
701 goto wait;
702 }
703 #endif
704 if (!(_res.options & RES_INSECURE2) &&
705 !res_queriesmatch(buf, buf + buflen,
706 ans, ans + anssiz)) {
707 /*
708 * response contains wrong query? ignore it.
709 * XXX - potential security hazard could
710 * be detected here.
711 */
712 DprintQ((_res.options & RES_DEBUG) ||
713 (_res.pfcode & RES_PRF_REPLY),
714 (stdout, ";; wrong query name:\n"),
715 ans, (resplen>anssiz)?anssiz:resplen);
716 goto wait;
717 }
718 if (anhp->rcode == SERVFAIL ||
719 anhp->rcode == NOTIMP ||
720 anhp->rcode == REFUSED) {
721 DprintQ(_res.options & RES_DEBUG,
722 (stdout, "server rejected query:\n"),
723 ans, (resplen>anssiz)?anssiz:resplen);
724 badns |= (1 << ns);
725 res_close();
726 /* don't retry if called from dig */
727 if (!_res.pfcode)
728 goto next_ns;
729 }
730 if (!(_res.options & RES_IGNTC) && anhp->tc) {
731 /*
732 * get rest of answer;
733 * use TCP with same server.
734 */
735 Dprint(_res.options & RES_DEBUG,
736 (stdout, ";; truncated answer\n"));
737 v_circuit = 1;
738 res_close();
739 goto same_ns;
740 }
741 } /*if vc/dg*/
742 Dprint((_res.options & RES_DEBUG) ||
743 ((_res.pfcode & RES_PRF_REPLY) &&
744 (_res.pfcode & RES_PRF_HEAD1)),
745 (stdout, ";; got answer:\n"));
746 DprintQ((_res.options & RES_DEBUG) ||
747 (_res.pfcode & RES_PRF_REPLY),
748 (stdout, ""),
749 ans, (resplen>anssiz)?anssiz:resplen);
750 /*
751 * If using virtual circuits, we assume that the first server
752 * is preferred over the rest (i.e. it is on the local
753 * machine) and only keep that one open.
754 * If we have temporarily opened a virtual circuit,
755 * or if we haven't been asked to keep a socket open,
756 * close the socket.
757 */
758 if ((v_circuit && (!(_res.options & RES_USEVC) || ns != 0)) ||
759 !(_res.options & RES_STAYOPEN)) {
760 res_close();
761 }
762 if (Rhook) {
763 int done = 0, loops = 0;
764
765 do {
766 res_sendhookact act;
767
768 act = (*Rhook)(nsap, buf, buflen,
769 ans, anssiz, &resplen);
770 switch (act) {
771 case res_goahead:
772 case res_done:
773 done = 1;
774 break;
775 case res_nextns:
776 res_close();
777 goto next_ns;
778 case res_modified:
779 /* give the hook another try */
780 if (++loops < 42) /*doug adams*/
781 break;
782 /*FALLTHROUGH*/
783 case res_error:
784 /*FALLTHROUGH*/
785 default:
786 return (-1);
787 }
788 } while (!done);
789
790 }
791 return (resplen);
792 next_ns: ;
793 } /*foreach ns*/
794 } /*foreach retry*/
795 res_close();
796 if (!v_circuit)
797 if (!gotsomewhere)
798 errno = ECONNREFUSED; /* no nameservers found */
799 else
800 errno = ETIMEDOUT; /* no answer obtained */
801 else
802 errno = terrno;
803 return (-1);
804 }
805
806 /*
807 * This routine is for closing the socket if a virtual circuit is used and
808 * the program wants to close it. This provides support for endhostent()
809 * which expects to close the socket.
810 *
811 * This routine is not expected to be user visible.
812 */
813 void
res_close()814 res_close()
815 {
816 if (s >= 0) {
817 (void) close(s);
818 s = -1;
819 connected = 0;
820 vc = 0;
821 }
822 }
823
824 #ifdef ultrix
825 /* ultrix 4.0 had some icky packaging in its libc.a. alias for it here.
826 * there is more gunk of this kind over in res_debug.c.
827 */
828
829 void
_res_close()830 _res_close()
831 {
832 res_close();
833 }
834
835 #undef res_send
836 int
res_send(buf,buflen,ans,anssiz)837 res_send(buf, buflen, ans, anssiz)
838 const u_char *buf;
839 int buflen;
840 u_char *ans;
841 int anssiz;
842 {
843 return (__res_send(buf, buflen, ans, anssiz));
844 }
845 #endif /* Ultrix 4.0 hackery */
846