2 * ++Copyright++ 1988, 1993
4 * Copyright (c) 1988, 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
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 * 4. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * 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
52 #if defined(LIBC_SCCS) && !defined(lint)
53 static char sccsid
[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
54 static char rcsid
[] = "$Id$";
55 #endif /* LIBC_SCCS and not lint */
57 #include <sys/types.h>
58 #include <sys/param.h>
59 #include <netinet/in.h>
60 #include <arpa/inet.h>
61 #include <arpa/nameser.h>
68 #if defined(BSD) && (BSD >= 199306)
72 # include "../conf/portability.h"
75 #if defined(USE_OPTIONS_H)
76 # include <../conf/options.h>
80 #define MAXPACKET PACKETSZ
82 #define MAXPACKET 1024
85 const char *hostalias
__P((const char *));
89 * Formulate a normal query, send, and await answer.
90 * Returned answer is placed in supplied buffer "answer".
91 * Perform preliminary check of answer, returning success only
92 * if no error is indicated and the answer count is nonzero.
93 * Return the size of the response on success, -1 on error.
94 * Error number is left in h_errno.
96 * Caller must parse answer and determine whether it answers the question.
99 res_query(name
, class, type
, answer
, anslen
)
100 const char *name
; /* domain name */
101 int class, type
; /* class and type of query */
102 u_char
*answer
; /* buffer to put answer */
103 int anslen
; /* size of answer buffer */
105 u_char buf
[MAXPACKET
];
106 register HEADER
*hp
= (HEADER
*) answer
;
109 hp
->rcode
= NOERROR
; /* default */
111 if ((_res
.options
& RES_INIT
) == 0 && res_init() == -1) {
112 __set_h_errno (NETDB_INTERNAL
);
116 if (_res
.options
& RES_DEBUG
)
117 printf(";; res_query(%s, %d, %d)\n", name
, class, type
);
120 n
= res_mkquery(QUERY
, name
, class, type
, NULL
, 0, NULL
,
124 if (_res
.options
& RES_DEBUG
)
125 printf(";; res_query: mkquery failed\n");
127 __set_h_errno (NO_RECOVERY
);
130 n
= res_send(buf
, n
, answer
, anslen
);
133 if (_res
.options
& RES_DEBUG
)
134 printf(";; res_query: send error\n");
136 __set_h_errno (TRY_AGAIN
);
140 if (hp
->rcode
!= NOERROR
|| ntohs(hp
->ancount
) == 0) {
142 if (_res
.options
& RES_DEBUG
)
143 printf(";; rcode = %d, ancount=%d\n", hp
->rcode
,
148 __set_h_errno (HOST_NOT_FOUND
);
151 __set_h_errno (TRY_AGAIN
);
154 __set_h_errno (NO_DATA
);
160 __set_h_errno (NO_RECOVERY
);
169 * Formulate a normal query, send, and retrieve answer in supplied buffer.
170 * Return the size of the response on success, -1 on error.
171 * If enabled, implement search rules until answer or unrecoverable failure
172 * is detected. Error code, if any, is left in h_errno.
175 res_search(name
, class, type
, answer
, anslen
)
176 const char *name
; /* domain name */
177 int class, type
; /* class and type of query */
178 u_char
*answer
; /* buffer to put answer */
179 int anslen
; /* size of answer */
181 register const char *cp
, * const *domain
;
182 HEADER
*hp
= (HEADER
*) answer
;
184 int trailing_dot
, ret
, saved_herrno
;
185 int got_nodata
= 0, got_servfail
= 0, tried_as_is
= 0;
187 if ((_res
.options
& RES_INIT
) == 0 && res_init() == -1) {
188 __set_h_errno (NETDB_INTERNAL
);
192 __set_h_errno (HOST_NOT_FOUND
); /* default, if we never query */
194 for (cp
= name
; *cp
; cp
++)
195 dots
+= (*cp
== '.');
197 if (cp
> name
&& *--cp
== '.')
201 * if there aren't any dots, it could be a user-level alias
203 if (!dots
&& (cp
= __hostalias(name
)) != NULL
)
204 return (res_query(cp
, class, type
, answer
, anslen
));
207 * If there are dots in the name already, let's just give it a try
208 * 'as is'. The threshold can be set with the "ndots" option.
211 if (dots
>= _res
.ndots
) {
212 ret
= res_querydomain(name
, NULL
, class, type
, answer
, anslen
);
215 saved_herrno
= h_errno
;
220 * We do at least one level of search if
221 * - there is no dot and RES_DEFNAME is set, or
222 * - there is at least one dot, there is no trailing dot,
223 * and RES_DNSRCH is set.
225 if ((!dots
&& (_res
.options
& RES_DEFNAMES
)) ||
226 (dots
&& !trailing_dot
&& (_res
.options
& RES_DNSRCH
))) {
229 for (domain
= (const char * const *)_res
.dnsrch
;
233 ret
= res_querydomain(name
, *domain
, class, type
,
239 * If no server present, give up.
240 * If name isn't found in this domain,
241 * keep trying higher domains in the search list
242 * (if that's enabled).
243 * On a NO_DATA error, keep trying, otherwise
244 * a wildcard entry of another type could keep us
245 * from finding this entry higher in the domain.
246 * If we get some other error (negative answer or
247 * server failure), then stop searching up,
248 * but try the input name below in case it's
251 if (errno
== ECONNREFUSED
) {
252 __set_h_errno (TRY_AGAIN
);
264 if (hp
->rcode
== SERVFAIL
) {
265 /* try next search element, if any */
271 /* anything else implies that we're done */
275 /* if we got here for some reason other than DNSRCH,
276 * we only wanted one iteration of the loop, so stop.
278 if (!(_res
.options
& RES_DNSRCH
))
283 /* if we have not already tried the name "as is", do that now.
284 * note that we do this regardless of how many dots were in the
285 * name or whether it ends with a dot.
288 ret
= res_querydomain(name
, NULL
, class, type
, answer
, anslen
);
293 /* if we got here, we didn't satisfy the search.
294 * if we did an initial full query, return that query's h_errno
295 * (note that we wouldn't be here if that query had succeeded).
296 * else if we ever got a nodata, send that back as the reason.
297 * else send back meaningless h_errno, that being the one from
298 * the last DNSRCH we did.
300 if (saved_herrno
!= -1)
301 __set_h_errno (saved_herrno
);
303 __set_h_errno (NO_DATA
);
304 else if (got_servfail
)
305 __set_h_errno (TRY_AGAIN
);
310 * Perform a call on res_query on the concatenation of name and domain,
311 * removing a trailing dot from name if domain is NULL.
314 res_querydomain(name
, domain
, class, type
, answer
, anslen
)
315 const char *name
, *domain
;
316 int class, type
; /* class and type of query */
317 u_char
*answer
; /* buffer to put answer */
318 int anslen
; /* size of answer */
320 char nbuf
[MAXDNAME
* 2 + 2];
321 const char *longname
= nbuf
;
324 if ((_res
.options
& RES_INIT
) == 0 && res_init() == -1) {
325 __set_h_errno (NETDB_INTERNAL
);
329 if (_res
.options
& RES_DEBUG
)
330 printf(";; res_querydomain(%s, %s, %d, %d)\n",
331 name
, domain
?domain
:"<Nil>", class, type
);
333 if (domain
== NULL
) {
335 * Check for trailing '.';
336 * copy without '.' if present.
338 n
= strlen(name
) - 1;
339 if (n
!= (0 - 1) && name
[n
] == '.'
340 && n
< (int) (sizeof(nbuf
) - 1)) {
341 bcopy(name
, nbuf
, n
);
346 sprintf(nbuf
, "%.*s.%.*s", MAXDNAME
, name
, MAXDNAME
, domain
);
348 return (res_query(longname
, class, type
, answer
, anslen
));
353 register const char *name
;
355 register char *cp1
, *cp2
;
359 static char abuf
[MAXDNAME
];
361 if (_res
.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 (!strcasecmp(buf
, name
)) {
375 while (isspace(*++cp1
))
379 for (cp2
= cp1
+ 1; *cp2
&& !isspace(*cp2
); ++cp2
)
381 abuf
[sizeof(abuf
) - 1] = *cp2
= '\0';
382 strncpy(abuf
, cp1
, sizeof(abuf
) - 1);