2 * ++Copyright++ 1985, 1989, 1993
4 * Copyright (c) 1985, 1989, 1993
5 * The Regents of the University of California. All rights reserved.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
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11 * notice, this list of conditions and the following disclaimer.
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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
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20 * may be used to endorse or promote products derived from this software
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37 * Permission to use, copy, modify, and distribute this software for any
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45 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
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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 8.9 1996/08/05 08:31:35 vixie Exp $";
59 #endif /* LIBC_SCCS and not lint */
62 * if you talk to a lot
63 * of multi-homed SunOS
64 * ("broken") name servers.
66 #define CHECK_SRVR_ADDR 1 /* XXX - should be in options.h */
69 * Send query to name server and wait for reply.
72 #include <sys/types.h>
73 #include <sys/param.h>
75 #include <sys/socket.h>
77 #include <netinet/in.h>
78 #include <arpa/nameser.h>
79 #include <arpa/inet.h>
85 #if defined(BSD) && (BSD >= 199306)
90 # include "../conf/portability.h"
93 #if defined(USE_OPTIONS_H)
94 # include <../conf/options.h>
97 void _res_close __P((void));
99 static int s = -1; /* socket used for communications */
100 static int connected = 0; /* is the socket connected */
101 static int vc = 0; /* is the socket a virtual ciruit? */
104 /* XXX - should be in portability.h */
106 #define FD_SETSIZE 32
107 #define FD_SET(n, p) ((p)->fds_bits[(n)/NFDBITS] |= (1 << ((n) % NFDBITS)))
108 #define FD_CLR(n, p) ((p)->fds_bits[(n)/NFDBITS] &= ~(1 << ((n) % NFDBITS)))
109 #define FD_ISSET(n, p) ((p)->fds_bits[(n)/NFDBITS] & (1 << ((n) % NFDBITS)))
110 #define FD_ZERO(p) bzero((char *)(p), sizeof(*(p)))
113 /* XXX - this should be done in portability.h */
114 #if (defined(BSD) && (BSD >= 199103)) || defined(linux)
115 # define CAN_RECONNECT 1
117 # define CAN_RECONNECT 0
121 # define Dprint(cond, args) /*empty*/
122 # define DprintQ(cond, args, query, size) /*empty*/
123 # define Aerror(file, string, error, address) /*empty*/
124 # define Perror(file, string, error) /*empty*/
126 # define Dprint(cond, args) if (cond) {fprintf args;} else {}
127 # define DprintQ(cond, args, query, size) if (cond) {\
129 __fp_nquery(query, size, stdout);\
132 Aerror(file, string, error, address)
136 struct sockaddr_in address;
140 if (_res.options & RES_DEBUG) {
141 fprintf(file, "res_send: %s ([%s].%u): %s\n",
143 inet_ntoa(address.sin_addr),
144 ntohs(address.sin_port),
150 Perror(file, string, error)
157 if (_res.options & RES_DEBUG) {
158 fprintf(file, "res_send: %s: %s\n",
159 string, strerror(error));
165 static res_send_qhook Qhook = NULL;
166 static res_send_rhook Rhook = NULL;
169 res_send_setqhook(hook)
177 res_send_setrhook(hook)
185 * res_isourserver(ina)
186 * looks up "ina" in _res.ns_addr_list[]
191 * paul vixie, 29may94
195 const struct sockaddr_in *inp;
197 struct sockaddr_in ina;
198 register int ns, ret;
202 for (ns = 0; ns < _res.nscount; ns++) {
203 register const struct sockaddr_in *srv = &_res.nsaddr_list[ns];
205 if (srv->sin_family == ina.sin_family &&
206 srv->sin_port == ina.sin_port &&
207 (srv->sin_addr.s_addr == INADDR_ANY ||
208 srv->sin_addr.s_addr == ina.sin_addr.s_addr)) {
217 * res_nameinquery(name, type, class, buf, eom)
218 * look for (name,type,class) in the query section of packet (buf,eom)
224 * paul vixie, 29may94
227 res_nameinquery(name, type, class, buf, eom)
229 register int type, class;
230 const u_char *buf, *eom;
232 register const u_char *cp = buf + HFIXEDSZ;
233 int qdcount = ntohs(((HEADER*)buf)->qdcount);
235 while (qdcount-- > 0) {
236 char tname[MAXDNAME+1];
237 register int n, ttype, tclass;
239 n = dn_expand(buf, eom, cp, tname, sizeof tname);
243 ttype = _getshort(cp); cp += INT16SZ;
244 tclass = _getshort(cp); cp += INT16SZ;
247 strcasecmp(tname, name) == 0)
254 * res_queriesmatch(buf1, eom1, buf2, eom2)
255 * is there a 1:1 mapping of (name,type,class)
256 * in (buf1,eom1) and (buf2,eom2)?
259 * 0 : not a 1:1 mapping
260 * >0 : is a 1:1 mapping
262 * paul vixie, 29may94
265 res_queriesmatch(buf1, eom1, buf2, eom2)
266 const u_char *buf1, *eom1;
267 const u_char *buf2, *eom2;
269 register const u_char *cp = buf1 + HFIXEDSZ;
270 int qdcount = ntohs(((HEADER*)buf1)->qdcount);
272 if (qdcount != ntohs(((HEADER*)buf2)->qdcount))
274 while (qdcount-- > 0) {
275 char tname[MAXDNAME+1];
276 register int n, ttype, tclass;
278 n = dn_expand(buf1, eom1, cp, tname, sizeof tname);
282 ttype = _getshort(cp); cp += INT16SZ;
283 tclass = _getshort(cp); cp += INT16SZ;
284 if (!res_nameinquery(tname, ttype, tclass, buf2, eom2))
291 res_send(buf, buflen, ans, anssiz)
297 HEADER *hp = (HEADER *) buf;
298 HEADER *anhp = (HEADER *) ans;
299 int gotsomewhere, connreset, terrno, try, v_circuit, resplen, ns;
301 u_int badns; /* XXX NSMAX can't exceed #/bits in this var */
303 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
304 /* errno should have been set by res_init() in this case. */
307 DprintQ((_res.options & RES_DEBUG) || (_res.pfcode & RES_PRF_QUERY),
308 (stdout, ";; res_send()\n"), buf, buflen);
309 v_circuit = (_res.options & RES_USEVC) || buflen > PACKETSZ;
316 * Send request, RETRY times, or until successful
318 for (try = 0; try < _res.retry; try++) {
319 for (ns = 0; ns < _res.nscount; ns++) {
320 struct sockaddr_in *nsap = &_res.nsaddr_list[ns];
322 if (badns & (1 << ns)) {
328 int done = 0, loops = 0;
333 act = (*Qhook)(&nsap, &buf, &buflen,
334 ans, anssiz, &resplen);
345 /* give the hook another try */
346 if (++loops < 42) /*doug adams*/
357 Dprint(_res.options & RES_DEBUG,
358 (stdout, ";; Querying server (# %d) address = %s\n",
359 ns + 1, inet_ntoa(nsap->sin_addr)));
368 * Use virtual circuit;
369 * at most one attempt per server.
373 if ((s < 0) || (!vc)) {
377 s = socket(PF_INET, SOCK_STREAM, 0);
380 Perror(stderr, "socket(vc)", errno);
384 if (connect(s, (struct sockaddr *)nsap,
385 sizeof(struct sockaddr)) < 0) {
387 Aerror(stderr, "connect/vc",
396 * Send length & message
398 putshort((u_short)buflen, (u_char*)&len);
399 iov[0].iov_base = (caddr_t)&len;
400 iov[0].iov_len = INT16SZ;
401 iov[1].iov_base = (caddr_t)buf;
402 iov[1].iov_len = buflen;
403 if (writev(s, iov, 2) != (INT16SZ + buflen)) {
405 Perror(stderr, "write failed", errno);
411 * Receive length & response
416 while ((n = read(s, (char *)cp, (int)len)) > 0) {
423 Perror(stderr, "read failed", errno);
426 * A long running process might get its TCP
427 * connection reset if the remote server was
428 * restarted. Requery the server instead of
429 * trying a new one. When there is only one
430 * server, this means that a query might work
431 * instead of failing. We only allow one reset
432 * per query to prevent looping.
434 if (terrno == ECONNRESET && !connreset) {
442 resplen = _getshort(ans);
443 if (resplen > anssiz) {
444 Dprint(_res.options & RES_DEBUG,
445 (stdout, ";; response truncated\n")
453 (n = read(s, (char *)cp, (int)len)) > 0) {
459 Perror(stderr, "read(vc)", errno);
465 * Flush rest of answer
466 * so connection stays in synch.
469 len = resplen - anssiz;
473 n = (len > sizeof(junk)
476 if ((n = read(s, junk, n)) > 0)
483 * The calling applicating has bailed out of
484 * a previous call and failed to arrange to have
485 * the circuit closed or the server has got
486 * itself confused. Anyway drop the packet and
487 * wait for the correct one.
489 if (hp->id != anhp->id) {
490 DprintQ((_res.options & RES_DEBUG) ||
491 (_res.pfcode & RES_PRF_REPLY),
492 (stdout, ";; old answer (unexpected):\n"),
493 ans, (resplen>anssiz)?anssiz:resplen);
500 struct timeval timeout;
502 struct sockaddr_in from;
508 s = socket(PF_INET, SOCK_DGRAM, 0);
514 Perror(stderr, "socket(dg)", errno);
520 * On a 4.3BSD+ machine (client and server,
521 * actually), sending to a nameserver datagram
522 * port with no nameserver will cause an
523 * ICMP port unreachable message to be returned.
524 * If our datagram socket is "connected" to the
525 * server, we get an ECONNREFUSED error on the next
526 * socket operation, and select returns if the
527 * error message is received. We can thus detect
528 * the absence of a nameserver without timing out.
529 * If we have sent queries to at least two servers,
530 * however, we don't want to remain connected,
531 * as we wish to receive answers from the first
534 if (_res.nscount == 1 || (try == 0 && ns == 0)) {
536 * Connect only if we are sure we won't
537 * receive a response from another server.
540 if (connect(s, (struct sockaddr *)nsap,
541 sizeof(struct sockaddr)
552 if (send(s, (char*)buf, buflen, 0) != buflen) {
553 Perror(stderr, "send", errno);
560 * Disconnect if we want to listen
561 * for responses from more than one server.
565 struct sockaddr_in no_addr;
567 no_addr.sin_family = AF_INET;
568 no_addr.sin_addr.s_addr = INADDR_ANY;
569 no_addr.sin_port = 0;
575 int s1 = socket(PF_INET, SOCK_DGRAM,0);
580 Dprint(_res.options & RES_DEBUG,
581 (stdout, ";; new DG socket\n"))
586 if (sendto(s, (char*)buf, buflen, 0,
587 (struct sockaddr *)nsap,
588 sizeof(struct sockaddr))
590 Aerror(stderr, "sendto", errno, *nsap);
600 timeout.tv_sec = (_res.retrans << try);
602 timeout.tv_sec /= _res.nscount;
603 if ((long) timeout.tv_sec <= 0)
609 n = select(s+1, &dsmask, (fd_set *)NULL,
610 (fd_set *)NULL, &timeout);
614 Perror(stderr, "select", errno);
622 Dprint(_res.options & RES_DEBUG,
623 (stdout, ";; timeout\n"));
629 fromlen = sizeof(struct sockaddr_in);
630 resplen = recvfrom(s, (char*)ans, anssiz, 0,
631 (struct sockaddr *)&from, &fromlen);
633 Perror(stderr, "recvfrom", errno);
638 if (hp->id != anhp->id) {
640 * response from old query, ignore it.
641 * XXX - potential security hazard could
644 DprintQ((_res.options & RES_DEBUG) ||
645 (_res.pfcode & RES_PRF_REPLY),
646 (stdout, ";; old answer:\n"),
647 ans, (resplen>anssiz)?anssiz:resplen);
651 if (!(_res.options & RES_INSECURE1) &&
652 !res_isourserver(&from)) {
654 * response from wrong server? ignore it.
655 * XXX - potential security hazard could
658 DprintQ((_res.options & RES_DEBUG) ||
659 (_res.pfcode & RES_PRF_REPLY),
660 (stdout, ";; not our server:\n"),
661 ans, (resplen>anssiz)?anssiz:resplen);
665 if (!(_res.options & RES_INSECURE2) &&
666 !res_queriesmatch(buf, buf + buflen,
667 ans, ans + anssiz)) {
669 * response contains wrong query? ignore it.
670 * XXX - potential security hazard could
673 DprintQ((_res.options & RES_DEBUG) ||
674 (_res.pfcode & RES_PRF_REPLY),
675 (stdout, ";; wrong query name:\n"),
676 ans, (resplen>anssiz)?anssiz:resplen);
679 if (anhp->rcode == SERVFAIL ||
680 anhp->rcode == NOTIMP ||
681 anhp->rcode == REFUSED) {
682 DprintQ(_res.options & RES_DEBUG,
683 (stdout, "server rejected query:\n"),
684 ans, (resplen>anssiz)?anssiz:resplen);
687 /* don't retry if called from dig */
691 if (!(_res.options & RES_IGNTC) && anhp->tc) {
693 * get rest of answer;
694 * use TCP with same server.
696 Dprint(_res.options & RES_DEBUG,
697 (stdout, ";; truncated answer\n"));
703 Dprint((_res.options & RES_DEBUG) ||
704 ((_res.pfcode & RES_PRF_REPLY) &&
705 (_res.pfcode & RES_PRF_HEAD1)),
706 (stdout, ";; got answer:\n"));
707 DprintQ((_res.options & RES_DEBUG) ||
708 (_res.pfcode & RES_PRF_REPLY),
710 ans, (resplen>anssiz)?anssiz:resplen);
712 * If using virtual circuits, we assume that the first server
713 * is preferred over the rest (i.e. it is on the local
714 * machine) and only keep that one open.
715 * If we have temporarily opened a virtual circuit,
716 * or if we haven't been asked to keep a socket open,
719 if ((v_circuit && (!(_res.options & RES_USEVC) || ns != 0)) ||
720 !(_res.options & RES_STAYOPEN)) {
724 int done = 0, loops = 0;
729 act = (*Rhook)(nsap, buf, buflen,
730 ans, anssiz, &resplen);
740 /* give the hook another try */
741 if (++loops < 42) /*doug adams*/
759 errno = ECONNREFUSED; /* no nameservers found */
761 errno = ETIMEDOUT; /* no answer obtained */
768 * This routine is for closing the socket if a virtual circuit is used and
769 * the program wants to close it. This provides support for endhostent()
770 * which expects to close the socket.
772 * This routine is not expected to be user visible.