xref: /titanic_50/usr/src/lib/libresolv2/common/resolv/res_query.c (revision 42ed7838f131b8f58d6c95db1c7e3a6a3e6ea7e4)
1 /*
2  * Portions Copyright (C) 2004, 2005, 2008  Internet Systems Consortium, Inc. ("ISC")
3  * Portions Copyright (C) 1996-2001, 2003  Internet Software Consortium.
4  *
5  * Permission to use, copy, modify, and/or distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15  * PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 /*
19  * Copyright (c) 1988, 1993
20  *    The Regents of the University of California.  All rights reserved.
21  *
22  * Redistribution and use in source and binary forms, with or without
23  * modification, are permitted provided that the following conditions
24  * are met:
25  * 1. Redistributions of source code must retain the above copyright
26  *    notice, this list of conditions and the following disclaimer.
27  * 2. Redistributions in binary form must reproduce the above copyright
28  *    notice, this list of conditions and the following disclaimer in the
29  *    documentation and/or other materials provided with the distribution.
30  * 3. All advertising materials mentioning features or use of this software
31  *    must display the following acknowledgement:
32  * 	This product includes software developed by the University of
33  * 	California, Berkeley and its contributors.
34  * 4. Neither the name of the University nor the names of its contributors
35  *    may be used to endorse or promote products derived from this software
36  *    without specific prior written permission.
37  *
38  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
39  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
40  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
41  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
42  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
43  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
44  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
45  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
46  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
47  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48  * SUCH DAMAGE.
49  */
50 
51 /*
52  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
53  *
54  * Permission to use, copy, modify, and distribute this software for any
55  * purpose with or without fee is hereby granted, provided that the above
56  * copyright notice and this permission notice appear in all copies, and that
57  * the name of Digital Equipment Corporation not be used in advertising or
58  * publicity pertaining to distribution of the document or software without
59  * specific, written prior permission.
60  *
61  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
62  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
63  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
64  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
65  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
66  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
67  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
68  * SOFTWARE.
69  */
70 
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 1.11 2008/11/14 02:36:51 marka Exp $";
74 #endif /* LIBC_SCCS and not lint */
75 
76 #include "port_before.h"
77 #include <sys/types.h>
78 #include <sys/param.h>
79 #include <netinet/in.h>
80 #include <arpa/inet.h>
81 #include <arpa/nameser.h>
82 #include <ctype.h>
83 #include <errno.h>
84 #include <netdb.h>
85 #include <resolv.h>
86 #include <stdio.h>
87 #include <stdlib.h>
88 #include <string.h>
89 #include "port_after.h"
90 
91 /* Options.  Leave them on. */
92 #define DEBUG
93 
94 #if PACKETSZ > 1024
95 #define MAXPACKET	PACKETSZ
96 #else
97 #define MAXPACKET	1024
98 #endif
99 
100 /*%
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.
107  *
108  * Caller must parse answer and determine whether it answers the question.
109  */
110 int
111 res_nquery(res_state statp,
112 	   const char *name,	/*%< domain name */
113 	   int class, int type,	/*%< class and type of query */
114 	   u_char *answer,	/*%< buffer to put answer */
115 	   int anslen)		/*%< size of answer buffer */
116 {
117 	u_char buf[MAXPACKET];
118 	HEADER *hp = (HEADER *) answer;
119 	u_int oflags;
120 	u_char *rdata;
121 	int n;
122 
123 	oflags = statp->_flags;
124 
125 again:
126 	hp->rcode = NOERROR;	/*%< default */
127 #ifdef DEBUG
128 	if (statp->options & RES_DEBUG)
129 		printf(";; res_query(%s, %d, %d)\n", name, class, type);
130 #endif
131 
132 	n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
133 			 buf, sizeof(buf));
134 #ifdef RES_USE_EDNS0
135 	if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
136 	    (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) {
137 		n = res_nopt(statp, n, buf, sizeof(buf), anslen);
138 		rdata = &buf[n];
139 		if (n > 0 && (statp->options & RES_NSID) != 0U) {
140 			n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
141 					   NS_OPT_NSID, 0, NULL);
142 		}
143 	}
144 #endif
145 	if (n <= 0) {
146 #ifdef DEBUG
147 		if (statp->options & RES_DEBUG)
148 			printf(";; res_query: mkquery failed\n");
149 #endif
150 		RES_SET_H_ERRNO(statp, NO_RECOVERY);
151 		return (n);
152 	}
153 
154 	n = res_nsend(statp, buf, n, answer, anslen);
155 	if (n < 0) {
156 #ifdef RES_USE_EDNS0
157 		/* if the query choked with EDNS0, retry without EDNS0 */
158 		if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
159 		    ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
160 			statp->_flags |= RES_F_EDNS0ERR;
161 			if (statp->options & RES_DEBUG)
162 				printf(";; res_nquery: retry without EDNS0\n");
163 			goto again;
164 		}
165 #endif
166 #ifdef DEBUG
167 		if (statp->options & RES_DEBUG)
168 			printf(";; res_query: send error\n");
169 #endif
170 		RES_SET_H_ERRNO(statp, TRY_AGAIN);
171 		return (n);
172 	}
173 
174 	if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
175 #ifdef DEBUG
176 		if (statp->options & RES_DEBUG)
177 			printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
178 			       p_rcode(hp->rcode),
179 			       ntohs(hp->ancount),
180 			       ntohs(hp->nscount),
181 			       ntohs(hp->arcount));
182 #endif
183 		switch (hp->rcode) {
184 		case NXDOMAIN:
185 			RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
186 			break;
187 		case SERVFAIL:
188 			RES_SET_H_ERRNO(statp, TRY_AGAIN);
189 			break;
190 		case NOERROR:
191 			RES_SET_H_ERRNO(statp, NO_DATA);
192 			break;
193 		case FORMERR:
194 		case NOTIMP:
195 		case REFUSED:
196 		default:
197 			RES_SET_H_ERRNO(statp, NO_RECOVERY);
198 			break;
199 		}
200 		return (-1);
201 	}
202 	return (n);
203 }
204 
205 /*%
206  * Formulate a normal query, send, and retrieve answer in supplied buffer.
207  * Return the size of the response on success, -1 on error.
208  * If enabled, implement search rules until answer or unrecoverable failure
209  * is detected.  Error code, if any, is left in H_ERRNO.
210  */
211 int
212 res_nsearch(res_state statp,
213 	    const char *name,	/*%< domain name */
214 	    int class, int type,	/*%< class and type of query */
215 	    u_char *answer,	/*%< buffer to put answer */
216 	    int anslen)		/*%< size of answer */
217 {
218 	const char *cp, * const *domain;
219 	HEADER *hp = (HEADER *) answer;
220 	char tmp[NS_MAXDNAME];
221 	u_int dots;
222 	int trailing_dot, ret, saved_herrno;
223 	int got_nodata = 0, got_servfail = 0, root_on_list = 0;
224 	int tried_as_is = 0;
225 	int searched = 0;
226 
227 	errno = 0;
228 	RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);  /*%< True if we never query. */
229 	dots = 0;
230 	for (cp = name; *cp != '\0'; cp++)
231 		dots += (*cp == '.');
232 	trailing_dot = 0;
233 	if (cp > name && *--cp == '.')
234 		trailing_dot++;
235 
236 	/* If there aren't any dots, it could be a user-level alias. */
237 	if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
238 		return (res_nquery(statp, cp, class, type, answer, anslen));
239 
240 	/*
241 	 * If there are enough dots in the name, let's just give it a
242 	 * try 'as is'. The threshold can be set with the "ndots" option.
243 	 * Also, query 'as is', if there is a trailing dot in the name.
244 	 */
245 	saved_herrno = -1;
246 	if (dots >= statp->ndots || trailing_dot) {
247 		ret = res_nquerydomain(statp, name, NULL, class, type,
248 					 answer, anslen);
249 		if (ret > 0 || trailing_dot)
250 			return (ret);
251 		saved_herrno = statp->res_h_errno;
252 		tried_as_is++;
253 	}
254 
255 	/*
256 	 * We do at least one level of search if
257 	 *	- there is no dot and RES_DEFNAME is set, or
258 	 *	- there is at least one dot, there is no trailing dot,
259 	 *	  and RES_DNSRCH is set.
260 	 */
261 	if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
262 	    (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
263 		int done = 0;
264 
265 		for (domain = (const char * const *)statp->dnsrch;
266 		     *domain && !done;
267 		     domain++) {
268 			searched = 1;
269 
270 			if (domain[0][0] == '\0' ||
271 			    (domain[0][0] == '.' && domain[0][1] == '\0'))
272 				root_on_list++;
273 
274 			ret = res_nquerydomain(statp, name, *domain,
275 					       class, type,
276 					       answer, anslen);
277 			if (ret > 0)
278 				return (ret);
279 
280 			/*
281 			 * If no server present, give up.
282 			 * If name isn't found in this domain,
283 			 * keep trying higher domains in the search list
284 			 * (if that's enabled).
285 			 * On a NO_DATA error, keep trying, otherwise
286 			 * a wildcard entry of another type could keep us
287 			 * from finding this entry higher in the domain.
288 			 * If we get some other error (negative answer or
289 			 * server failure), then stop searching up,
290 			 * but try the input name below in case it's
291 			 * fully-qualified.
292 			 */
293 			if (errno == ECONNREFUSED) {
294 				RES_SET_H_ERRNO(statp, TRY_AGAIN);
295 				return (-1);
296 			}
297 
298 			switch (statp->res_h_errno) {
299 			case NO_DATA:
300 				got_nodata++;
301 				/* FALLTHROUGH */
302 			case HOST_NOT_FOUND:
303 				/* keep trying */
304 				break;
305 			case TRY_AGAIN:
306 				if (hp->rcode == SERVFAIL) {
307 					/* try next search element, if any */
308 					got_servfail++;
309 					break;
310 				}
311 				/* FALLTHROUGH */
312 			default:
313 				/* anything else implies that we're done */
314 				done++;
315 			}
316 
317 			/* if we got here for some reason other than DNSRCH,
318 			 * we only wanted one iteration of the loop, so stop.
319 			 */
320 			if ((statp->options & RES_DNSRCH) == 0U)
321 				done++;
322 		}
323 	}
324 
325 	/*
326 	 * If the query has not already been tried as is then try it
327 	 * unless RES_NOTLDQUERY is set and there were no dots.
328 	 */
329 	if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
330 	    !(tried_as_is || root_on_list)) {
331 		ret = res_nquerydomain(statp, name, NULL, class, type,
332 				       answer, anslen);
333 		if (ret > 0)
334 			return (ret);
335 	}
336 
337 	/* if we got here, we didn't satisfy the search.
338 	 * if we did an initial full query, return that query's H_ERRNO
339 	 * (note that we wouldn't be here if that query had succeeded).
340 	 * else if we ever got a nodata, send that back as the reason.
341 	 * else send back meaningless H_ERRNO, that being the one from
342 	 * the last DNSRCH we did.
343 	 */
344 	if (saved_herrno != -1)
345 		RES_SET_H_ERRNO(statp, saved_herrno);
346 	else if (got_nodata)
347 		RES_SET_H_ERRNO(statp, NO_DATA);
348 	else if (got_servfail)
349 		RES_SET_H_ERRNO(statp, TRY_AGAIN);
350 	return (-1);
351 }
352 
353 /*%
354  * Perform a call on res_query on the concatenation of name and domain,
355  * removing a trailing dot from name if domain is NULL.
356  */
357 int
358 res_nquerydomain(res_state statp,
359 	    const char *name,
360 	    const char *domain,
361 	    int class, int type,	/*%< class and type of query */
362 	    u_char *answer,		/*%< buffer to put answer */
363 	    int anslen)		/*%< size of answer */
364 {
365 	char nbuf[MAXDNAME];
366 	const char *longname = nbuf;
367 	int n, d;
368 
369 #ifdef DEBUG
370 	if (statp->options & RES_DEBUG)
371 		printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
372 		       name, domain?domain:"<Nil>", class, type);
373 #endif
374 	if (domain == NULL) {
375 		/*
376 		 * Check for trailing '.';
377 		 * copy without '.' if present.
378 		 */
379 		n = strlen(name);
380 		if (n >= MAXDNAME) {
381 			RES_SET_H_ERRNO(statp, NO_RECOVERY);
382 			return (-1);
383 		}
384 		n--;
385 		if (n >= 0 && name[n] == '.') {
386 			strncpy(nbuf, name, n);
387 			nbuf[n] = '\0';
388 		} else
389 			longname = name;
390 	} else {
391 		n = strlen(name);
392 		d = strlen(domain);
393 		if (n + d + 1 >= MAXDNAME) {
394 			RES_SET_H_ERRNO(statp, NO_RECOVERY);
395 			return (-1);
396 		}
397 		sprintf(nbuf, "%s.%s", name, domain);
398 	}
399 	return (res_nquery(statp, longname, class, type, answer, anslen));
400 }
401 
402 const char *
403 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
404 	char *file, *cp1, *cp2;
405 	char buf[BUFSIZ];
406 	FILE *fp;
407 
408 	if (statp->options & RES_NOALIASES)
409 		return (NULL);
410 	file = getenv("HOSTALIASES");
411 	if (file == NULL || (fp = fopen(file, "r")) == NULL)
412 		return (NULL);
413 	setbuf(fp, NULL);
414 	buf[sizeof(buf) - 1] = '\0';
415 	while (fgets(buf, sizeof(buf), fp)) {
416 		for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
417 			;
418 		if (!*cp1)
419 			break;
420 		*cp1 = '\0';
421 		if (ns_samename(buf, name) == 1) {
422 			while (isspace((unsigned char)*++cp1))
423 				;
424 			if (!*cp1)
425 				break;
426 			for (cp2 = cp1 + 1; *cp2 &&
427 			     !isspace((unsigned char)*cp2); ++cp2)
428 				;
429 			*cp2 = '\0';
430 			strncpy(dst, cp1, siz - 1);
431 			dst[siz - 1] = '\0';
432 			fclose(fp);
433 			return (dst);
434 		}
435 	}
436 	fclose(fp);
437 	return (NULL);
438 }
439 
440 /*! \file */
441