2 * Copyright (c) 1988, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
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14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
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18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
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29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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35 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
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.
44 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
45 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
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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
55 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
57 * Permission to use, copy, modify, and distribute this software for any
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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
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67 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
71 #if defined(LIBC_SCCS) && !defined(lint)
72 static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
73 static const char rcsid[] = "$Id: res_query.c,v 1.4 2001/01/16 22:33:15 mellon Exp $";
74 #endif /* LIBC_SCCS and not lint */
76 #include <sys/types.h>
77 #include <sys/param.h>
78 #include <netinet/in.h>
79 #include <arpa/inet.h>
86 #include <sys/socket.h>
88 #include "minires/minires.h"
89 #include "arpa/nameser.h"
91 /* Options. Leave them on. */
95 #define MAXPACKET PACKETSZ
97 #define MAXPACKET 1024
101 * Formulate a normal query, send, and await answer.
102 * Returned answer is placed in supplied buffer "answer".
103 * Perform preliminary check of answer, returning success only
104 * if no error is indicated and the answer count is nonzero.
105 * Return the size of the response on success, -1 on error.
106 * Error number is left in H_ERRNO.
108 * Caller must parse answer and determine whether it answers the question.
111 res_nquery(res_state statp,
112 const char *name, /* domain name */
113 ns_class class, ns_type type, /* class and type of query */
114 double *answer, /* buffer to put answer */
116 unsigned *ansret) /* size of answer buffer */
118 double buf[MAXPACKET / sizeof (double)];
119 HEADER *hp = (HEADER *) answer;
123 hp->rcode = NOERROR; /* default */
126 if (statp->options & RES_DEBUG)
127 printf(";; res_query(%s, %d, %d)\n", name, class, type);
130 rcode = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
131 buf, sizeof(buf), &n);
132 if (rcode != ISC_R_SUCCESS) {
134 if (statp->options & RES_DEBUG)
135 printf(";; res_query: mkquery failed\n");
137 RES_SET_H_ERRNO(statp, NO_RECOVERY);
140 rcode = res_nsend(statp, buf, n, answer, anslen, &n);
141 if (rcode != ISC_R_SUCCESS) {
143 if (statp->options & RES_DEBUG)
144 printf(";; res_query: send error\n");
146 RES_SET_H_ERRNO(statp, TRY_AGAIN);
150 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
152 if (statp->options & RES_DEBUG)
153 printf(";; rcode = %d, ancount=%d\n", hp->rcode,
158 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
161 RES_SET_H_ERRNO(statp, TRY_AGAIN);
164 RES_SET_H_ERRNO(statp, NO_DATA);
170 RES_SET_H_ERRNO(statp, NO_RECOVERY);
173 return ns_rcode_to_isc (hp -> rcode);
176 return ISC_R_SUCCESS;
181 * Formulate a normal query, send, and retrieve answer in supplied buffer.
182 * Return the size of the response on success, -1 on error.
183 * If enabled, implement search rules until answer or unrecoverable failure
184 * is detected. Error code, if any, is left in H_ERRNO.
187 res_nsearch(res_state statp,
188 const char *name, /* domain name */
189 ns_class class, ns_type type, /* class and type of query */
190 double *answer, /* buffer to put answer */
192 unsigned *ansret) /* size of answer */
194 const char *cp, * const *domain;
195 HEADER *hp = (HEADER *) answer;
196 char tmp[NS_MAXDNAME];
198 int trailing_dot, ret;
199 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
203 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */
206 for (cp = name; *cp != '\0'; cp++)
207 dots += (*cp == '.');
209 if (cp > name && *--cp == '.')
212 /* If there aren't any dots, it could be a user-level alias. */
213 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
214 return res_nquery(statp, cp, class, type,
215 answer, anslen, ansret);
218 * If there are enough dots in the name, do no searching.
219 * (The threshold can be set with the "ndots" option.)
221 if (dots >= statp->ndots || trailing_dot)
222 return res_nquerydomain(statp, name, NULL, class, type,
223 answer, anslen, ansret);
226 * We do at least one level of search if
227 * - there is no dot and RES_DEFNAME is set, or
228 * - there is at least one dot, there is no trailing dot,
229 * and RES_DNSRCH is set.
231 if ((!dots && (statp->options & RES_DEFNAMES) != 0) ||
232 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) {
235 for (domain = (const char * const *)statp->dnsrch;
239 if (domain[0][0] == '\0' ||
240 (domain[0][0] == '.' && domain[0][1] == '\0'))
243 rcode = res_nquerydomain(statp, name, *domain,
245 answer, anslen, &ret);
246 if (rcode == ISC_R_SUCCESS && ret > 0) {
252 * If no server present, give up.
253 * If name isn't found in this domain,
254 * keep trying higher domains in the search list
255 * (if that's enabled).
256 * On a NO_DATA error, keep trying, otherwise
257 * a wildcard entry of another type could keep us
258 * from finding this entry higher in the domain.
259 * If we get some other error (negative answer or
260 * server failure), then stop searching up,
261 * but try the input name below in case it's
264 if (errno == ECONNREFUSED) {
265 RES_SET_H_ERRNO(statp, TRY_AGAIN);
266 return ISC_R_CONNREFUSED;
269 switch (statp->res_h_errno) {
277 if (hp->rcode == SERVFAIL) {
278 /* try next search element, if any */
284 /* anything else implies that we're done */
288 /* if we got here for some reason other than DNSRCH,
289 * we only wanted one iteration of the loop, so stop.
291 if ((statp->options & RES_DNSRCH) == 0)
297 * If the name has any dots at all, and "." is not on the search
298 * list, then try an as-is query now.
301 rcode = res_nquerydomain(statp, name, NULL, class, type,
302 answer, anslen, &ret);
303 if (rcode == ISC_R_SUCCESS && ret > 0) {
309 /* if we got here, we didn't satisfy the search.
310 * if we did an initial full query, return that query's H_ERRNO
311 * (note that we wouldn't be here if that query had succeeded).
312 * else if we ever got a nodata, send that back as the reason.
313 * else send back meaningless H_ERRNO, that being the one from
314 * the last DNSRCH we did.
317 RES_SET_H_ERRNO(statp, NO_DATA);
318 return ISC_R_NOTFOUND;
319 } else if (got_servfail) {
320 RES_SET_H_ERRNO(statp, TRY_AGAIN);
321 return ISC_R_TIMEDOUT;
323 return ISC_R_UNEXPECTED;
328 * Perform a call on res_query on the concatenation of name and domain,
329 * removing a trailing dot from name if domain is NULL.
332 res_nquerydomain(res_state statp,
335 ns_class class, ns_type type,
341 const char *longname = nbuf;
345 if (statp->options & RES_DEBUG)
346 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
347 name, domain?domain:"<Nil>", class, type);
349 if (domain == NULL) {
351 * Check for trailing '.';
352 * copy without '.' if present.
356 RES_SET_H_ERRNO(statp, NO_RECOVERY);
357 return ISC_R_NOSPACE;
360 if (n >= 0 && name[n] == '.') {
361 strncpy(nbuf, name, (unsigned)n);
368 if (n + d + 1 >= MAXDNAME) {
369 RES_SET_H_ERRNO(statp, NO_RECOVERY);
370 return ISC_R_NOSPACE;
372 sprintf(nbuf, "%s.%s", name, domain);
374 return res_nquery(statp,
375 longname, class, type, answer, anslen, ansret);
379 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
380 char *file, *cp1, *cp2;
384 if (statp->options & RES_NOALIASES)
386 file = getenv("HOSTALIASES");
387 if (file == NULL || (fp = fopen(file, "r")) == NULL)
390 buf[sizeof(buf) - 1] = '\0';
391 while (fgets(buf, sizeof(buf), fp)) {
392 for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
397 if (ns_samename(buf, name) == 1) {
398 while (isspace(*++cp1))
402 for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
405 strncpy(dst, cp1, siz - 1);