res_query.c revision 1dc9e472e19acfe6dc7f41e429236e7eef7ceda1
1/*	$NetBSD: res_query.c,v 1.7 2006/01/24 17:41:25 christos Exp $	*/
2
3/*
4 * Copyright (c) 1988, 1993
5 *    The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
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 * 3. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 * 	This product includes software developed by the University of
18 * 	California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36/*
37 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
38 *
39 * Permission to use, copy, modify, and distribute this software for any
40 * purpose with or without fee is hereby granted, provided that the above
41 * copyright notice and this permission notice appear in all copies, and that
42 * the name of Digital Equipment Corporation not be used in advertising or
43 * publicity pertaining to distribution of the document or software without
44 * specific, written prior permission.
45 *
46 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
47 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
48 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
49 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
50 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
51 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
52 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
53 * SOFTWARE.
54 */
55
56/*
57 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
58 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
59 *
60 * Permission to use, copy, modify, and distribute this software for any
61 * purpose with or without fee is hereby granted, provided that the above
62 * copyright notice and this permission notice appear in all copies.
63 *
64 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
65 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
66 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
67 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
68 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
69 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
70 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
71 */
72
73#include <sys/cdefs.h>
74#if defined(LIBC_SCCS) && !defined(lint)
75#ifdef notdef
76static const char sccsid[] = "@(#)res_query.c	8.1 (Berkeley) 6/4/93";
77static const char rcsid[] = "Id: res_query.c,v 1.2.2.3.4.2 2004/03/16 12:34:19 marka Exp";
78#else
79__RCSID("$NetBSD: res_query.c,v 1.7 2006/01/24 17:41:25 christos Exp $");
80#endif
81#endif /* LIBC_SCCS and not lint */
82
83
84
85#include <sys/types.h>
86#include <sys/param.h>
87#include <netinet/in.h>
88#include <arpa/inet.h>
89#include "arpa_nameser.h"
90#include <ctype.h>
91#include <errno.h>
92#include <netdb.h>
93#ifdef ANDROID_CHANGES
94#include "resolv_private.h"
95#else
96#include <resolv.h>
97#endif
98#include <stdio.h>
99#include <stdlib.h>
100#include <unistd.h>
101#include <string.h>
102
103#define DISABLE_HOST_ALIAS 1
104
105/* Options.  Leave them on. */
106#ifndef DEBUG
107#define DEBUG
108#endif
109
110#if PACKETSZ > 1024
111#define MAXPACKET	PACKETSZ
112#else
113#define MAXPACKET	1024
114#endif
115
116/*
117 * Formulate a normal query, send, and await answer.
118 * Returned answer is placed in supplied buffer "answer".
119 * Perform preliminary check of answer, returning success only
120 * if no error is indicated and the answer count is nonzero.
121 * Return the size of the response on success, -1 on error.
122 * Error number is left in H_ERRNO.
123 *
124 * Caller must parse answer and determine whether it answers the question.
125 */
126int
127res_nquery(res_state statp,
128	   const char *name,	/* domain name */
129	   int class, int type,	/* class and type of query */
130	   u_char *answer,	/* buffer to put answer */
131	   int anslen)		/* size of answer buffer */
132{
133	u_char buf[MAXPACKET];
134	HEADER *hp = (HEADER *)(void *)answer;
135	int n;
136	u_int oflags;
137
138	oflags = statp->_flags;
139
140again:
141	hp->rcode = NOERROR;	/* default */
142
143#ifdef DEBUG
144	if (statp->options & RES_DEBUG)
145		printf(";; res_query(%s, %d, %d)\n", name, class, type);
146#endif
147
148	n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
149			 buf, sizeof(buf));
150#ifdef RES_USE_EDNS0
151	if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
152	    (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U)
153		n = res_nopt(statp, n, buf, sizeof(buf), anslen);
154#endif
155	if (n <= 0) {
156#ifdef DEBUG
157		if (statp->options & RES_DEBUG)
158			printf(";; res_query: mkquery failed\n");
159#endif
160		RES_SET_H_ERRNO(statp, NO_RECOVERY);
161		return (n);
162	}
163	n = res_nsend(statp, buf, n, answer, anslen);
164	if (n < 0) {
165#ifdef RES_USE_EDNS0
166		/* if the query choked with EDNS0, retry without EDNS0 */
167		if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
168		    ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
169			statp->_flags |= RES_F_EDNS0ERR;
170			if (statp->options & RES_DEBUG)
171				printf(";; res_nquery: retry without EDNS0\n");
172			goto again;
173		}
174#endif
175#ifdef DEBUG
176		if (statp->options & RES_DEBUG)
177			printf(";; res_query: send error\n");
178#endif
179		RES_SET_H_ERRNO(statp, TRY_AGAIN);
180		return (n);
181	}
182
183	if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
184#ifdef DEBUG
185		if (statp->options & RES_DEBUG)
186			printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
187			       p_rcode(hp->rcode),
188			       ntohs(hp->ancount),
189			       ntohs(hp->nscount),
190			       ntohs(hp->arcount));
191#endif
192		switch (hp->rcode) {
193		case NXDOMAIN:
194			RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
195			break;
196		case SERVFAIL:
197			RES_SET_H_ERRNO(statp, TRY_AGAIN);
198			break;
199		case NOERROR:
200			RES_SET_H_ERRNO(statp, NO_DATA);
201			break;
202		case FORMERR:
203		case NOTIMP:
204		case REFUSED:
205		default:
206			RES_SET_H_ERRNO(statp, NO_RECOVERY);
207			break;
208		}
209		return (-1);
210	}
211	return (n);
212}
213
214/*
215 * Formulate a normal query, send, and retrieve answer in supplied buffer.
216 * Return the size of the response on success, -1 on error.
217 * If enabled, implement search rules until answer or unrecoverable failure
218 * is detected.  Error code, if any, is left in H_ERRNO.
219 */
220int
221res_nsearch(res_state statp,
222	    const char *name,	/* domain name */
223	    int class, int type,	/* class and type of query */
224	    u_char *answer,	/* buffer to put answer */
225	    int anslen)		/* size of answer */
226{
227	const char *cp, * const *domain;
228	HEADER *hp = (HEADER *)(void *)answer;
229	char tmp[NS_MAXDNAME];
230	u_int dots;
231	int trailing_dot, ret, saved_herrno;
232	int got_nodata = 0, got_servfail = 0, root_on_list = 0;
233	int tried_as_is = 0;
234	int searched = 0;
235
236	errno = 0;
237	RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);  /* True if we never query. */
238
239	dots = 0;
240	for (cp = name; *cp != '\0'; cp++)
241		dots += (*cp == '.');
242	trailing_dot = 0;
243	if (cp > name && *--cp == '.')
244		trailing_dot++;
245
246	/* If there aren't any dots, it could be a user-level alias. */
247	if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
248		return (res_nquery(statp, cp, class, type, answer, anslen));
249
250	/*
251	 * If there are enough dots in the name, let's just give it a
252	 * try 'as is'. The threshold can be set with the "ndots" option.
253	 * Also, query 'as is', if there is a trailing dot in the name.
254	 */
255	saved_herrno = -1;
256	if (dots >= statp->ndots || trailing_dot) {
257		ret = res_nquerydomain(statp, name, NULL, class, type,
258					 answer, anslen);
259		if (ret > 0 || trailing_dot)
260			return (ret);
261		saved_herrno = statp->res_h_errno;
262		tried_as_is++;
263	}
264
265	/*
266	 * We do at least one level of search if
267	 *	- there is no dot and RES_DEFNAME is set, or
268	 *	- there is at least one dot, there is no trailing dot,
269	 *	  and RES_DNSRCH is set.
270	 */
271	if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
272	    (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
273		int done = 0;
274
275		for (domain = (const char * const *)statp->dnsrch;
276		     *domain && !done;
277		     domain++) {
278			searched = 1;
279
280			if (domain[0][0] == '\0' ||
281			    (domain[0][0] == '.' && domain[0][1] == '\0'))
282				root_on_list++;
283
284			ret = res_nquerydomain(statp, name, *domain,
285					       class, type,
286					       answer, anslen);
287			if (ret > 0)
288				return (ret);
289
290			/*
291			 * If no server present, give up.
292			 * If name isn't found in this domain,
293			 * keep trying higher domains in the search list
294			 * (if that's enabled).
295			 * On a NO_DATA error, keep trying, otherwise
296			 * a wildcard entry of another type could keep us
297			 * from finding this entry higher in the domain.
298			 * If we get some other error (negative answer or
299			 * server failure), then stop searching up,
300			 * but try the input name below in case it's
301			 * fully-qualified.
302			 */
303			if (errno == ECONNREFUSED) {
304				RES_SET_H_ERRNO(statp, TRY_AGAIN);
305				return (-1);
306			}
307
308			switch (statp->res_h_errno) {
309			case NO_DATA:
310				got_nodata++;
311				/* FALLTHROUGH */
312			case HOST_NOT_FOUND:
313				/* keep trying */
314				break;
315			case TRY_AGAIN:
316				if (hp->rcode == SERVFAIL) {
317					/* try next search element, if any */
318					got_servfail++;
319					break;
320				}
321				/* FALLTHROUGH */
322			default:
323				/* anything else implies that we're done */
324				done++;
325			}
326
327			/* if we got here for some reason other than DNSRCH,
328			 * we only wanted one iteration of the loop, so stop.
329			 */
330			if ((statp->options & RES_DNSRCH) == 0U)
331				done++;
332		}
333	}
334
335	/*
336	 * If the query has not already been tried as is then try it
337	 * unless RES_NOTLDQUERY is set and there were no dots.
338	 */
339	if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
340	    !(tried_as_is || root_on_list)) {
341		ret = res_nquerydomain(statp, name, NULL, class, type,
342				       answer, anslen);
343		if (ret > 0)
344			return (ret);
345	}
346
347	/* if we got here, we didn't satisfy the search.
348	 * if we did an initial full query, return that query's H_ERRNO
349	 * (note that we wouldn't be here if that query had succeeded).
350	 * else if we ever got a nodata, send that back as the reason.
351	 * else send back meaningless H_ERRNO, that being the one from
352	 * the last DNSRCH we did.
353	 */
354	if (saved_herrno != -1)
355		RES_SET_H_ERRNO(statp, saved_herrno);
356	else if (got_nodata)
357		RES_SET_H_ERRNO(statp, NO_DATA);
358	else if (got_servfail)
359		RES_SET_H_ERRNO(statp, TRY_AGAIN);
360	return (-1);
361}
362
363/*
364 * Perform a call on res_query on the concatenation of name and domain,
365 * removing a trailing dot from name if domain is NULL.
366 */
367int
368res_nquerydomain(res_state statp,
369	    const char *name,
370	    const char *domain,
371	    int class, int type,	/* class and type of query */
372	    u_char *answer,		/* buffer to put answer */
373	    int anslen)		/* size of answer */
374{
375	char nbuf[MAXDNAME];
376	const char *longname = nbuf;
377	int n, d;
378
379#ifdef DEBUG
380	if (statp->options & RES_DEBUG)
381		printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
382		       name, domain?domain:"<Nil>", class, type);
383#endif
384	if (domain == NULL) {
385		/*
386		 * Check for trailing '.';
387		 * copy without '.' if present.
388		 */
389		n = strlen(name);
390		if (n >= MAXDNAME) {
391			RES_SET_H_ERRNO(statp, NO_RECOVERY);
392			return (-1);
393		}
394		n--;
395		if (n >= 0 && name[n] == '.') {
396			strncpy(nbuf, name, (size_t)n);
397			nbuf[n] = '\0';
398		} else
399			longname = name;
400	} else {
401		n = strlen(name);
402		d = strlen(domain);
403		if (n + d + 1 >= MAXDNAME) {
404			RES_SET_H_ERRNO(statp, NO_RECOVERY);
405			return (-1);
406		}
407		sprintf(nbuf, "%s.%s", name, domain);
408	}
409	return (res_nquery(statp, longname, class, type, answer, anslen));
410}
411
412const char *
413res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
414	return (NULL);
415}
416