1 /*
2  * Copyright 2006 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 
98 /* Options.  Leave them on. */
99 #define DEBUG
100 
101 #if PACKETSZ > 1024
102 #define MAXPACKET	PACKETSZ
103 #else
104 #define MAXPACKET	1024
105 #endif
106 
107 /*
108  * Formulate a normal query, send, and await answer.
109  * Returned answer is placed in supplied buffer "answer".
110  * Perform preliminary check of answer, returning success only
111  * if no error is indicated and the answer count is nonzero.
112  * Return the size of the response on success, -1 on error.
113  * Error number is left in H_ERRNO.
114  *
115  * Caller must parse answer and determine whether it answers the question.
116  */
117 int
118 res_nquery(res_state statp,
119 	   const char *name,	/* domain name */
120 	   int class, int type,	/* class and type of query */
121 	   u_char *answer,	/* buffer to put answer */
122 	   int anslen)		/* size of answer buffer */
123 {
124 	u_char buf[MAXPACKET];
125 	HEADER *hp = (HEADER *) answer;
126 	int n;
127 	u_int oflags;
128 
129 	oflags = statp->_flags;
130 
131 again:
132 	hp->rcode = NOERROR;	/* default */
133 
134 #ifdef DEBUG
135 	if (statp->options & RES_DEBUG)
136 		printf(";; res_query(%s, %d, %d)\n", name, class, type);
137 #endif
138 
139 	n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
140 			 buf, sizeof(buf));
141 #ifdef RES_USE_EDNS0
142 	if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
143 	    (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
144 		n = res_nopt(statp, n, buf, sizeof(buf), anslen);
145 #endif
146 	if (n <= 0) {
147 #ifdef DEBUG
148 		if (statp->options & RES_DEBUG)
149 			printf(";; res_query: mkquery failed\n");
150 #endif
151 		RES_SET_H_ERRNO(statp, NO_RECOVERY);
152 		return (n);
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)) != 0 &&
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 
230 	dots = 0;
231 	for (cp = name; *cp != '\0'; cp++)
232 		dots += (*cp == '.');
233 	trailing_dot = 0;
234 	if (cp > name && *--cp == '.')
235 		trailing_dot++;
236 
237 	/* If there aren't any dots, it could be a user-level alias. */
238 	if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
239 		return (res_nquery(statp, cp, class, type, answer, anslen));
240 
241 	/*
242 	 * If there are enough dots in the name, let's just give it a
243 	 * try 'as is'. The threshold can be set with the "ndots" option.
244 	 * Also, query 'as is', if there is a trailing dot in the name.
245 	 */
246 	saved_herrno = -1;
247 	if (dots >= statp->ndots || trailing_dot) {
248 		ret = res_nquerydomain(statp, name, NULL, class, type,
249 					 answer, anslen);
250 		if (ret > 0 || trailing_dot)
251 			return (ret);
252 		saved_herrno = statp->res_h_errno;
253 		tried_as_is++;
254 	}
255 
256 	/*
257 	 * We do at least one level of search if
258 	 *	- there is no dot and RES_DEFNAME is set, or
259 	 *	- there is at least one dot, there is no trailing dot,
260 	 *	  and RES_DNSRCH is set.
261 	 */
262 	if ((!dots && (statp->options & RES_DEFNAMES) != 0) ||
263 	    (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) {
264 		int done = 0;
265 
266 		for (domain = (const char * const *)statp->dnsrch;
267 		     *domain && !done;
268 		     domain++) {
269 			searched = 1;
270 
271 			if (domain[0][0] == '\0' ||
272 			    (domain[0][0] == '.' && domain[0][1] == '\0'))
273 				root_on_list++;
274 
275 			ret = res_nquerydomain(statp, name, *domain,
276 					       class, type,
277 					       answer, anslen);
278 			if (ret > 0)
279 				return (ret);
280 
281 			/*
282 			 * If no server present, give up.
283 			 * If name isn't found in this domain,
284 			 * keep trying higher domains in the search list
285 			 * (if that's enabled).
286 			 * On a NO_DATA error, keep trying, otherwise
287 			 * a wildcard entry of another type could keep us
288 			 * from finding this entry higher in the domain.
289 			 * If we get some other error (negative answer or
290 			 * server failure), then stop searching up,
291 			 * but try the input name below in case it's
292 			 * fully-qualified.
293 			 */
294 			if (errno == ECONNREFUSED) {
295 				RES_SET_H_ERRNO(statp, TRY_AGAIN);
296 				return (-1);
297 			}
298 
299 			switch (statp->res_h_errno) {
300 			case NO_DATA:
301 				got_nodata++;
302 				/* FALLTHROUGH */
303 			case HOST_NOT_FOUND:
304 				/* keep trying */
305 				break;
306 			case TRY_AGAIN:
307 				if (hp->rcode == SERVFAIL) {
308 					/* try next search element, if any */
309 					got_servfail++;
310 					break;
311 				}
312 				/* FALLTHROUGH */
313 			default:
314 				/* anything else implies that we're done */
315 				done++;
316 			}
317 
318 			/* if we got here for some reason other than DNSRCH,
319 			 * we only wanted one iteration of the loop, so stop.
320 			 */
321 			if ((statp->options & RES_DNSRCH) == 0)
322 				done++;
323 		}
324 	}
325 
326 	/*
327 	 * If the query has not already been tried as is then try it
328 	 * unless RES_NOTLDQUERY is set and there were no dots.
329 	 */
330 	if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0) &&
331 	    !(tried_as_is || root_on_list)) {
332 		ret = res_nquerydomain(statp, name, NULL, class, type,
333 				       answer, anslen);
334 		if (ret > 0)
335 			return (ret);
336 	}
337 
338 	/* if we got here, we didn't satisfy the search.
339 	 * if we did an initial full query, return that query's H_ERRNO
340 	 * (note that we wouldn't be here if that query had succeeded).
341 	 * else if we ever got a nodata, send that back as the reason.
342 	 * else send back meaningless H_ERRNO, that being the one from
343 	 * the last DNSRCH we did.
344 	 */
345 	if (saved_herrno != -1)
346 		RES_SET_H_ERRNO(statp, saved_herrno);
347 	else if (got_nodata)
348 		RES_SET_H_ERRNO(statp, NO_DATA);
349 	else if (got_servfail)
350 		RES_SET_H_ERRNO(statp, TRY_AGAIN);
351 	return (-1);
352 }
353 
354 /*
355  * Perform a call on res_query on the concatenation of name and domain,
356  * removing a trailing dot from name if domain is NULL.
357  */
358 int
359 res_nquerydomain(res_state statp,
360 	    const char *name,
361 	    const char *domain,
362 	    int class, int type,	/* class and type of query */
363 	    u_char *answer,		/* buffer to put answer */
364 	    int anslen)		/* size of answer */
365 {
366 	char nbuf[MAXDNAME];
367 	const char *longname = nbuf;
368 	int n, d;
369 
370 #ifdef DEBUG
371 	if (statp->options & RES_DEBUG)
372 		printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
373 		       name, domain?domain:"<Nil>", class, type);
374 #endif
375 	if (domain == NULL) {
376 		/*
377 		 * Check for trailing '.';
378 		 * copy without '.' if present.
379 		 */
380 		n = strlen(name);
381 		if (n >= MAXDNAME) {
382 			RES_SET_H_ERRNO(statp, NO_RECOVERY);
383 			return (-1);
384 		}
385 		n--;
386 		if (n >= 0 && name[n] == '.') {
387 			strncpy(nbuf, name, n);
388 			nbuf[n] = '\0';
389 		} else
390 			longname = name;
391 	} else {
392 		n = strlen(name);
393 		d = strlen(domain);
394 		if (n + d + 1 >= MAXDNAME) {
395 			RES_SET_H_ERRNO(statp, NO_RECOVERY);
396 			return (-1);
397 		}
398 		sprintf(nbuf, "%s.%s", name, domain);
399 	}
400 	return (res_nquery(statp, longname, class, type, answer, anslen));
401 }
402 
403 const char *
404 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
405 	char *file, *cp1, *cp2;
406 	char buf[BUFSIZ];
407 	FILE *fp;
408 
409 	if (statp->options & RES_NOALIASES)
410 		return (NULL);
411 	file = getenv("HOSTALIASES");
412 #ifdef SUNW_AVOIDSTDIO_FDLIMIT
413 	 if (file == NULL || (fp = fopen(file, "rF")) == NULL)
414 #else
415 	 if (file == NULL || (fp = fopen(file, "r")) == NULL)
416 #endif
417 		return (NULL);
418 	setbuf(fp, NULL);
419 	buf[sizeof(buf) - 1] = '\0';
420 	while (fgets(buf, sizeof(buf), fp)) {
421 		for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
422 			;
423 		if (!*cp1)
424 			break;
425 		*cp1 = '\0';
426 		if (ns_samename(buf, name) == 1) {
427 			while (isspace((unsigned char)*++cp1))
428 				;
429 			if (!*cp1)
430 				break;
431 			for (cp2 = cp1 + 1; *cp2 &&
432 			     !isspace((unsigned char)*cp2); ++cp2)
433 				;
434 			*cp2 = '\0';
435 			strncpy(dst, cp1, siz - 1);
436 			dst[siz - 1] = '\0';
437 			fclose(fp);
438 			return (dst);
439 		}
440 	}
441 	fclose(fp);
442 	return (NULL);
443 }
444