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.
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 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
33 * Permission to use, copy, modify, and distribute this software for any
34 * purpose with or without fee is hereby granted, provided that the above
35 * copyright notice and this permission notice appear in all copies, and that
36 * the name of Digital Equipment Corporation not be used in advertising or
37 * publicity pertaining to distribution of the document or software without
38 * specific, written prior permission.
40 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
41 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
42 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
43 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
44 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
45 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
46 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
51 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
53 * Permission to use, copy, modify, and distribute this software for any
54 * purpose with or without fee is hereby granted, provided that the above
55 * copyright notice and this permission notice appear in all copies.
57 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
58 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
59 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
60 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
61 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
62 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
63 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
67 #if defined(LIBC_SCCS) && !defined(lint)
68 static const char sccsid
[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
69 static const char rcsid
[] = "$Id$";
70 #endif /* LIBC_SCCS and not lint */
72 #include <sys/types.h>
73 #include <sys/param.h>
74 #include <netinet/in.h>
75 #include <arpa/inet.h>
76 #include <arpa/nameser.h>
85 /* Options. Leave them on. */
89 #define MAXPACKET PACKETSZ
91 #define MAXPACKET 1024
95 * Formulate a normal query, send, and await answer.
96 * Returned answer is placed in supplied buffer "answer".
97 * Perform preliminary check of answer, returning success only
98 * if no error is indicated and the answer count is nonzero.
99 * Return the size of the response on success, -1 on error.
100 * Error number is left in H_ERRNO.
102 * Caller must parse answer and determine whether it answers the question.
105 res_nquery(res_state statp
,
106 const char *name
, /* domain name */
107 int class, int type
, /* class and type of query */
108 u_char
*answer
, /* buffer to put answer */
109 int anslen
) /* size of answer buffer */
111 u_char buf
[MAXPACKET
];
112 HEADER
*hp
= (HEADER
*) answer
;
115 hp
->rcode
= NOERROR
; /* default */
118 if (statp
->options
& RES_DEBUG
)
119 printf(";; res_query(%s, %d, %d)\n", name
, class, type
);
122 n
= res_nmkquery(statp
, QUERY
, name
, class, type
, NULL
, 0, NULL
,
126 if (statp
->options
& RES_DEBUG
)
127 printf(";; res_query: mkquery failed\n");
129 RES_SET_H_ERRNO(statp
, NO_RECOVERY
);
132 n
= res_nsend(statp
, buf
, n
, answer
, anslen
);
135 if (statp
->options
& RES_DEBUG
)
136 printf(";; res_query: send error\n");
138 RES_SET_H_ERRNO(statp
, TRY_AGAIN
);
142 if (hp
->rcode
!= NOERROR
|| ntohs(hp
->ancount
) == 0) {
144 if (statp
->options
& RES_DEBUG
)
145 printf(";; rcode = %d, ancount=%d\n", hp
->rcode
,
150 RES_SET_H_ERRNO(statp
, HOST_NOT_FOUND
);
153 RES_SET_H_ERRNO(statp
, TRY_AGAIN
);
156 RES_SET_H_ERRNO(statp
, NO_DATA
);
162 RES_SET_H_ERRNO(statp
, NO_RECOVERY
);
171 * Formulate a normal query, send, and retrieve answer in supplied buffer.
172 * Return the size of the response on success, -1 on error.
173 * If enabled, implement search rules until answer or unrecoverable failure
174 * is detected. Error code, if any, is left in H_ERRNO.
177 res_nsearch(res_state statp
,
178 const char *name
, /* domain name */
179 int class, int type
, /* class and type of query */
180 u_char
*answer
, /* buffer to put answer */
181 int anslen
) /* size of answer */
183 const char *cp
, * const *domain
;
184 HEADER
*hp
= (HEADER
*) answer
;
185 char tmp
[NS_MAXDNAME
];
187 int trailing_dot
, ret
;
188 int got_nodata
= 0, got_servfail
= 0, root_on_list
= 0;
191 RES_SET_H_ERRNO(statp
, HOST_NOT_FOUND
); /* True if we never query. */
194 for (cp
= name
; *cp
!= '\0'; cp
++)
195 dots
+= (*cp
== '.');
197 if (cp
> name
&& *--cp
== '.')
200 /* If there aren't any dots, it could be a user-level alias. */
201 if (!dots
&& (cp
= res_hostalias(statp
, name
, tmp
, sizeof tmp
))!= NULL
)
202 return (res_nquery(statp
, cp
, class, type
, answer
, anslen
));
205 * If there are enough dots in the name, do no searching.
206 * (The threshold can be set with the "ndots" option.)
208 if (dots
>= statp
->ndots
|| trailing_dot
)
209 return (res_nquerydomain(statp
, name
, NULL
, class, type
,
213 * We do at least one level of search if
214 * - there is no dot and RES_DEFNAME is set, or
215 * - there is at least one dot, there is no trailing dot,
216 * and RES_DNSRCH is set.
218 if ((!dots
&& (statp
->options
& RES_DEFNAMES
) != 0) ||
219 (dots
&& !trailing_dot
&& (statp
->options
& RES_DNSRCH
) != 0)) {
222 for (domain
= (const char * const *)statp
->dnsrch
;
226 if (domain
[0][0] == '\0' ||
227 (domain
[0][0] == '.' && domain
[0][1] == '\0'))
230 ret
= res_nquerydomain(statp
, name
, *domain
,
237 * If no server present, give up.
238 * If name isn't found in this domain,
239 * keep trying higher domains in the search list
240 * (if that's enabled).
241 * On a NO_DATA error, keep trying, otherwise
242 * a wildcard entry of another type could keep us
243 * from finding this entry higher in the domain.
244 * If we get some other error (negative answer or
245 * server failure), then stop searching up,
246 * but try the input name below in case it's
249 if (errno
== ECONNREFUSED
) {
250 RES_SET_H_ERRNO(statp
, TRY_AGAIN
);
254 switch (statp
->res_h_errno
) {
262 if (hp
->rcode
== SERVFAIL
) {
263 /* try next search element, if any */
269 /* anything else implies that we're done */
273 /* if we got here for some reason other than DNSRCH,
274 * we only wanted one iteration of the loop, so stop.
276 if ((statp
->options
& RES_DNSRCH
) == 0)
282 * If the name has any dots at all, and "." is not on the search
283 * list, then try an as-is query now.
286 ret
= res_nquerydomain(statp
, name
, NULL
, class, type
,
292 /* if we got here, we didn't satisfy the search.
293 * if we did an initial full query, return that query's H_ERRNO
294 * (note that we wouldn't be here if that query had succeeded).
295 * else if we ever got a nodata, send that back as the reason.
296 * else send back meaningless H_ERRNO, that being the one from
297 * the last DNSRCH we did.
300 RES_SET_H_ERRNO(statp
, NO_DATA
);
301 else if (got_servfail
)
302 RES_SET_H_ERRNO(statp
, TRY_AGAIN
);
307 * Perform a call on res_query on the concatenation of name and domain,
308 * removing a trailing dot from name if domain is NULL.
311 res_nquerydomain(res_state statp
,
314 int class, int type
, /* class and type of query */
315 u_char
*answer
, /* buffer to put answer */
316 int anslen
) /* size of answer */
319 const char *longname
= nbuf
;
323 if (statp
->options
& RES_DEBUG
)
324 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
325 name
, domain
?domain
:"<Nil>", class, type
);
327 if (domain
== NULL
) {
329 * Check for trailing '.';
330 * copy without '.' if present.
334 RES_SET_H_ERRNO(statp
, NO_RECOVERY
);
338 if (n
>= 0 && name
[n
] == '.') {
339 strncpy(nbuf
, name
, n
);
346 if (n
+ d
+ 1 >= MAXDNAME
) {
347 RES_SET_H_ERRNO(statp
, NO_RECOVERY
);
350 sprintf(nbuf
, "%s.%s", name
, domain
);
352 return (res_nquery(statp
, longname
, class, type
, answer
, anslen
));
356 res_hostalias(const res_state statp
, const char *name
, char *dst
, size_t siz
) {
357 char *file
, *cp1
, *cp2
;
361 if (statp
->options
& RES_NOALIASES
)
363 file
= __secure_getenv("HOSTALIASES");
364 if (file
== NULL
|| (fp
= fopen(file
, "r")) == NULL
)
367 buf
[sizeof(buf
) - 1] = '\0';
368 while (fgets(buf
, sizeof(buf
), fp
)) {
369 for (cp1
= buf
; *cp1
&& !isspace(*cp1
); ++cp1
)
374 if (ns_samename(buf
, name
) == 1) {
375 while (isspace(*++cp1
))
379 for (cp2
= cp1
+ 1; *cp2
&& !isspace(*cp2
); ++cp2
)
382 strncpy(dst
, cp1
, siz
- 1);