xref: /titanic_41/usr/src/lib/libresolv2/common/resolv/res_query.c (revision bdfc6d18da790deeec2e0eb09c625902defe2498)
1 /*
2  * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
3  * Use is subject to license terms.
4  */
5 
6 /*
7  * Copyright (c) 1988, 1993
8  *    The Regents of the University of California.  All rights reserved.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  * 	This product includes software developed by the University of
21  * 	California, Berkeley and its contributors.
22  * 4. Neither the name of the University nor the names of its contributors
23  *    may be used to endorse or promote products derived from this software
24  *    without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  */
38 
39 /*
40  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
41  *
42  * Permission to use, copy, modify, and distribute this software for any
43  * purpose with or without fee is hereby granted, provided that the above
44  * copyright notice and this permission notice appear in all copies, and that
45  * the name of Digital Equipment Corporation not be used in advertising or
46  * publicity pertaining to distribution of the document or software without
47  * specific, written prior permission.
48  *
49  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
50  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
51  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
52  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
53  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
54  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
55  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
56  * SOFTWARE.
57  */
58 
59 /*
60  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
61  *
62  * Permission to use, copy, modify, and distribute this software for any
63  * purpose with or without fee is hereby granted, provided that the above
64  * copyright notice and this permission notice appear in all copies.
65  *
66  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
67  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
68  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
69  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
70  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
71  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
72  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
73  * SOFTWARE.
74  */
75 
76 #pragma ident	"%Z%%M%	%I%	%E% SMI"
77 
78 #if defined(LIBC_SCCS) && !defined(lint)
79 static const char sccsid[] = "@(#)res_query.c	8.1 (Berkeley) 6/4/93";
80 static const char rcsid[] = "$Id: res_query.c,v 8.24 2003/01/31 15:25:58 vixie Exp $";
81 #endif /* LIBC_SCCS and not lint */
82 
83 #include "port_before.h"
84 #include <sys/types.h>
85 #include <sys/param.h>
86 #include <netinet/in.h>
87 #include <arpa/inet.h>
88 #include <arpa/nameser.h>
89 #include <ctype.h>
90 #include <errno.h>
91 #include <netdb.h>
92 #include <resolv.h>
93 #include <stdio.h>
94 #include <stdlib.h>
95 #include <string.h>
96 #include "port_after.h"
97 #ifdef	SUNW_AVOIDSTDIO_FDLIMIT
98 #include "../../../libnsl/include/nsl_stdio_prv.h"
99 #endif
100 
101 /* Options.  Leave them on. */
102 #define DEBUG
103 
104 #if PACKETSZ > 1024
105 #define MAXPACKET	PACKETSZ
106 #else
107 #define MAXPACKET	1024
108 #endif
109 
110 /*
111  * Formulate a normal query, send, and await answer.
112  * Returned answer is placed in supplied buffer "answer".
113  * Perform preliminary check of answer, returning success only
114  * if no error is indicated and the answer count is nonzero.
115  * Return the size of the response on success, -1 on error.
116  * Error number is left in H_ERRNO.
117  *
118  * Caller must parse answer and determine whether it answers the question.
119  */
120 int
121 res_nquery(res_state statp,
122 	   const char *name,	/* domain name */
123 	   int class, int type,	/* class and type of query */
124 	   u_char *answer,	/* buffer to put answer */
125 	   int anslen)		/* size of answer buffer */
126 {
127 	u_char buf[MAXPACKET];
128 	HEADER *hp = (HEADER *) answer;
129 	int n;
130 	u_int oflags;
131 
132 	oflags = statp->_flags;
133 
134 again:
135 	hp->rcode = NOERROR;	/* default */
136 
137 #ifdef DEBUG
138 	if (statp->options & RES_DEBUG)
139 		printf(";; res_query(%s, %d, %d)\n", name, class, type);
140 #endif
141 
142 	n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
143 			 buf, sizeof(buf));
144 #ifdef RES_USE_EDNS0
145 	if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
146 	    (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
147 		n = res_nopt(statp, n, buf, sizeof(buf), anslen);
148 #endif
149 	if (n <= 0) {
150 #ifdef DEBUG
151 		if (statp->options & RES_DEBUG)
152 			printf(";; res_query: mkquery failed\n");
153 #endif
154 		RES_SET_H_ERRNO(statp, NO_RECOVERY);
155 		return (n);
156 	}
157 	n = res_nsend(statp, buf, n, answer, anslen);
158 	if (n < 0) {
159 #ifdef RES_USE_EDNS0
160 		/* if the query choked with EDNS0, retry without EDNS0 */
161 		if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0 &&
162 		    ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
163 			statp->_flags |= RES_F_EDNS0ERR;
164 			if (statp->options & RES_DEBUG)
165 				printf(";; res_nquery: retry without EDNS0\n");
166 			goto again;
167 		}
168 #endif
169 #ifdef DEBUG
170 		if (statp->options & RES_DEBUG)
171 			printf(";; res_query: send error\n");
172 #endif
173 		RES_SET_H_ERRNO(statp, TRY_AGAIN);
174 		return (n);
175 	}
176 
177 	if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
178 #ifdef DEBUG
179 		if (statp->options & RES_DEBUG)
180 			printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
181 			       p_rcode(hp->rcode),
182 			       ntohs(hp->ancount),
183 			       ntohs(hp->nscount),
184 			       ntohs(hp->arcount));
185 #endif
186 		switch (hp->rcode) {
187 		case NXDOMAIN:
188 			RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
189 			break;
190 		case SERVFAIL:
191 			RES_SET_H_ERRNO(statp, TRY_AGAIN);
192 			break;
193 		case NOERROR:
194 			RES_SET_H_ERRNO(statp, NO_DATA);
195 			break;
196 		case FORMERR:
197 		case NOTIMP:
198 		case REFUSED:
199 		default:
200 			RES_SET_H_ERRNO(statp, NO_RECOVERY);
201 			break;
202 		}
203 		return (-1);
204 	}
205 	return (n);
206 }
207 
208 /*
209  * Formulate a normal query, send, and retrieve answer in supplied buffer.
210  * Return the size of the response on success, -1 on error.
211  * If enabled, implement search rules until answer or unrecoverable failure
212  * is detected.  Error code, if any, is left in H_ERRNO.
213  */
214 int
215 res_nsearch(res_state statp,
216 	    const char *name,	/* domain name */
217 	    int class, int type,	/* class and type of query */
218 	    u_char *answer,	/* buffer to put answer */
219 	    int anslen)		/* size of answer */
220 {
221 	const char *cp, * const *domain;
222 	HEADER *hp = (HEADER *) answer;
223 	char tmp[NS_MAXDNAME];
224 	u_int dots;
225 	int trailing_dot, ret, saved_herrno;
226 	int got_nodata = 0, got_servfail = 0, root_on_list = 0;
227 	int tried_as_is = 0;
228 	int searched = 0;
229 
230 	errno = 0;
231 	RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);  /* True if we never query. */
232 
233 	dots = 0;
234 	for (cp = name; *cp != '\0'; cp++)
235 		dots += (*cp == '.');
236 	trailing_dot = 0;
237 	if (cp > name && *--cp == '.')
238 		trailing_dot++;
239 
240 	/* If there aren't any dots, it could be a user-level alias. */
241 	if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
242 		return (res_nquery(statp, cp, class, type, answer, anslen));
243 
244 	/*
245 	 * If there are enough dots in the name, let's just give it a
246 	 * try 'as is'. The threshold can be set with the "ndots" option.
247 	 * Also, query 'as is', if there is a trailing dot in the name.
248 	 */
249 	saved_herrno = -1;
250 	if (dots >= statp->ndots || trailing_dot) {
251 		ret = res_nquerydomain(statp, name, NULL, class, type,
252 					 answer, anslen);
253 		if (ret > 0 || trailing_dot)
254 			return (ret);
255 		saved_herrno = statp->res_h_errno;
256 		tried_as_is++;
257 	}
258 
259 	/*
260 	 * We do at least one level of search if
261 	 *	- there is no dot and RES_DEFNAME is set, or
262 	 *	- there is at least one dot, there is no trailing dot,
263 	 *	  and RES_DNSRCH is set.
264 	 */
265 	if ((!dots && (statp->options & RES_DEFNAMES) != 0) ||
266 	    (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) {
267 		int done = 0;
268 
269 		for (domain = (const char * const *)statp->dnsrch;
270 		     *domain && !done;
271 		     domain++) {
272 			searched = 1;
273 
274 			if (domain[0][0] == '\0' ||
275 			    (domain[0][0] == '.' && domain[0][1] == '\0'))
276 				root_on_list++;
277 
278 			ret = res_nquerydomain(statp, name, *domain,
279 					       class, type,
280 					       answer, anslen);
281 			if (ret > 0)
282 				return (ret);
283 
284 			/*
285 			 * If no server present, give up.
286 			 * If name isn't found in this domain,
287 			 * keep trying higher domains in the search list
288 			 * (if that's enabled).
289 			 * On a NO_DATA error, keep trying, otherwise
290 			 * a wildcard entry of another type could keep us
291 			 * from finding this entry higher in the domain.
292 			 * If we get some other error (negative answer or
293 			 * server failure), then stop searching up,
294 			 * but try the input name below in case it's
295 			 * fully-qualified.
296 			 */
297 			if (errno == ECONNREFUSED) {
298 				RES_SET_H_ERRNO(statp, TRY_AGAIN);
299 				return (-1);
300 			}
301 
302 			switch (statp->res_h_errno) {
303 			case NO_DATA:
304 				got_nodata++;
305 				/* FALLTHROUGH */
306 			case HOST_NOT_FOUND:
307 				/* keep trying */
308 				break;
309 			case TRY_AGAIN:
310 				if (hp->rcode == SERVFAIL) {
311 					/* try next search element, if any */
312 					got_servfail++;
313 					break;
314 				}
315 				/* FALLTHROUGH */
316 			default:
317 				/* anything else implies that we're done */
318 				done++;
319 			}
320 
321 			/* if we got here for some reason other than DNSRCH,
322 			 * we only wanted one iteration of the loop, so stop.
323 			 */
324 			if ((statp->options & RES_DNSRCH) == 0)
325 				done++;
326 		}
327 	}
328 
329 	/*
330 	 * If the query has not already been tried as is then try it
331 	 * unless RES_NOTLDQUERY is set and there were no dots.
332 	 */
333 	if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0) &&
334 	    !(tried_as_is || root_on_list)) {
335 		ret = res_nquerydomain(statp, name, NULL, class, type,
336 				       answer, anslen);
337 		if (ret > 0)
338 			return (ret);
339 	}
340 
341 	/* if we got here, we didn't satisfy the search.
342 	 * if we did an initial full query, return that query's H_ERRNO
343 	 * (note that we wouldn't be here if that query had succeeded).
344 	 * else if we ever got a nodata, send that back as the reason.
345 	 * else send back meaningless H_ERRNO, that being the one from
346 	 * the last DNSRCH we did.
347 	 */
348 	if (saved_herrno != -1)
349 		RES_SET_H_ERRNO(statp, saved_herrno);
350 	else if (got_nodata)
351 		RES_SET_H_ERRNO(statp, NO_DATA);
352 	else if (got_servfail)
353 		RES_SET_H_ERRNO(statp, TRY_AGAIN);
354 	return (-1);
355 }
356 
357 /*
358  * Perform a call on res_query on the concatenation of name and domain,
359  * removing a trailing dot from name if domain is NULL.
360  */
361 int
362 res_nquerydomain(res_state statp,
363 	    const char *name,
364 	    const char *domain,
365 	    int class, int type,	/* class and type of query */
366 	    u_char *answer,		/* buffer to put answer */
367 	    int anslen)		/* size of answer */
368 {
369 	char nbuf[MAXDNAME];
370 	const char *longname = nbuf;
371 	int n, d;
372 
373 #ifdef DEBUG
374 	if (statp->options & RES_DEBUG)
375 		printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
376 		       name, domain?domain:"<Nil>", class, type);
377 #endif
378 	if (domain == NULL) {
379 		/*
380 		 * Check for trailing '.';
381 		 * copy without '.' if present.
382 		 */
383 		n = strlen(name);
384 		if (n >= MAXDNAME) {
385 			RES_SET_H_ERRNO(statp, NO_RECOVERY);
386 			return (-1);
387 		}
388 		n--;
389 		if (n >= 0 && name[n] == '.') {
390 			strncpy(nbuf, name, n);
391 			nbuf[n] = '\0';
392 		} else
393 			longname = name;
394 	} else {
395 		n = strlen(name);
396 		d = strlen(domain);
397 		if (n + d + 1 >= MAXDNAME) {
398 			RES_SET_H_ERRNO(statp, NO_RECOVERY);
399 			return (-1);
400 		}
401 		sprintf(nbuf, "%s.%s", name, domain);
402 	}
403 	return (res_nquery(statp, longname, class, type, answer, anslen));
404 }
405 
406 const char *
407 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
408 	char *file, *cp1, *cp2;
409 	char buf[BUFSIZ];
410 #ifdef	SUNW_AVOIDSTDIO_FDLIMIT
411 	__NSL_FILE *fp;
412 #else
413 	FILE *fp;
414 #endif
415 
416 	if (statp->options & RES_NOALIASES)
417 		return (NULL);
418 	file = getenv("HOSTALIASES");
419 #ifdef	SUNW_AVOIDSTDIO_FDLIMIT
420 	if (file == NULL || (fp = __nsl_fopen(file, "r")) == NULL)
421 #else
422 	 if (file == NULL || (fp = fopen(file, "r")) == NULL)
423 #endif
424 		return (NULL);
425 #ifndef	SUNW_AVOIDSTDIO_FDLIMIT
426 	setbuf(fp, NULL);
427 #endif
428 	buf[sizeof(buf) - 1] = '\0';
429 #ifdef	SUNW_AVOIDSTDIO_FDLIMIT
430 	while (__nsl_fgets(buf, sizeof(buf), fp)) {
431 #else
432 	while (fgets(buf, sizeof(buf), fp)) {
433 #endif
434 		for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
435 			;
436 		if (!*cp1)
437 			break;
438 		*cp1 = '\0';
439 		if (ns_samename(buf, name) == 1) {
440 			while (isspace((unsigned char)*++cp1))
441 				;
442 			if (!*cp1)
443 				break;
444 			for (cp2 = cp1 + 1; *cp2 &&
445 			     !isspace((unsigned char)*cp2); ++cp2)
446 				;
447 			*cp2 = '\0';
448 			strncpy(dst, cp1, siz - 1);
449 			dst[siz - 1] = '\0';
450 #ifdef	SUNW_AVOIDSTDIO_FDLIMIT
451 			__nsl_fclose(fp);
452 #else
453 			fclose(fp);
454 #endif
455 			return (dst);
456 		}
457 	}
458 #ifdef	SUNW_AVOIDSTDIO_FDLIMIT
459 	__nsl_fclose(fp);
460 #else
461 	fclose(fp);
462 #endif
463 	return (NULL);
464 }
465