Annotation of src/lib/libc/resolv/res_query.c, Revision 1.8
1.8 ! christos 1: /* $NetBSD: res_query.c,v 1.1.1.2 2007/01/27 21:45:39 christos Exp $ */
1.1 christos 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:
1.3 christos 73: #include <sys/cdefs.h>
1.1 christos 74: #if defined(LIBC_SCCS) && !defined(lint)
1.3 christos 75: #ifdef notdef
1.1 christos 76: static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
1.8 ! christos 77: static const char rcsid[] = "Id: res_query.c,v 1.7.18.1 2005/04/27 05:01:11 sra Exp";
1.3 christos 78: #else
1.8 ! christos 79: __RCSID("$NetBSD: res_query.c,v 1.7 2006/01/24 17:41:25 christos Exp $");
1.3 christos 80: #endif
1.1 christos 81: #endif /* LIBC_SCCS and not lint */
82:
83: #include "port_before.h"
1.4 christos 84:
85: #include "namespace.h"
1.1 christos 86: #include <sys/types.h>
87: #include <sys/param.h>
88: #include <netinet/in.h>
89: #include <arpa/inet.h>
90: #include <arpa/nameser.h>
91: #include <ctype.h>
92: #include <errno.h>
93: #include <netdb.h>
94: #include <resolv.h>
95: #include <stdio.h>
96: #include <stdlib.h>
1.6 christos 97: #include <unistd.h>
1.1 christos 98: #include <string.h>
99: #include "port_after.h"
100:
1.5 christos 101: #if 0
1.4 christos 102: #ifdef __weak_alias
103: __weak_alias(res_nquery,_res_nquery)
104: __weak_alias(res_nsearch,_res_nsearch)
105: __weak_alias(res_nquerydomain,__res_nquerydomain)
106: __weak_alias(res_hostalias,__res_hostalias)
107: #endif
1.5 christos 108: #endif
1.4 christos 109:
1.1 christos 110: /* Options. Leave them on. */
1.7 christos 111: #ifndef DEBUG
1.1 christos 112: #define DEBUG
1.7 christos 113: #endif
1.1 christos 114:
115: #if PACKETSZ > 1024
116: #define MAXPACKET PACKETSZ
117: #else
118: #define MAXPACKET 1024
119: #endif
120:
1.8 ! christos 121: /*%
1.1 christos 122: * Formulate a normal query, send, and await answer.
123: * Returned answer is placed in supplied buffer "answer".
124: * Perform preliminary check of answer, returning success only
125: * if no error is indicated and the answer count is nonzero.
126: * Return the size of the response on success, -1 on error.
127: * Error number is left in H_ERRNO.
128: *
129: * Caller must parse answer and determine whether it answers the question.
130: */
131: int
132: res_nquery(res_state statp,
1.8 ! christos 133: const char *name, /*%< domain name */
! 134: int class, int type, /*%< class and type of query */
! 135: u_char *answer, /*%< buffer to put answer */
! 136: int anslen) /*%< size of answer buffer */
1.1 christos 137: {
138: u_char buf[MAXPACKET];
1.2 christos 139: HEADER *hp = (HEADER *)(void *)answer;
1.1 christos 140: int n;
141: u_int oflags;
142:
143: oflags = statp->_flags;
144:
145: again:
1.8 ! christos 146: hp->rcode = NOERROR; /*%< default */
1.1 christos 147: #ifdef DEBUG
148: if (statp->options & RES_DEBUG)
149: printf(";; res_query(%s, %d, %d)\n", name, class, type);
150: #endif
151:
152: n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
153: buf, sizeof(buf));
154: #ifdef RES_USE_EDNS0
155: if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
156: (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U)
157: n = res_nopt(statp, n, buf, sizeof(buf), anslen);
158: #endif
159: if (n <= 0) {
160: #ifdef DEBUG
161: if (statp->options & RES_DEBUG)
162: printf(";; res_query: mkquery failed\n");
163: #endif
164: RES_SET_H_ERRNO(statp, NO_RECOVERY);
165: return (n);
166: }
167: n = res_nsend(statp, buf, n, answer, anslen);
168: if (n < 0) {
169: #ifdef RES_USE_EDNS0
170: /* if the query choked with EDNS0, retry without EDNS0 */
171: if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
172: ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
173: statp->_flags |= RES_F_EDNS0ERR;
174: if (statp->options & RES_DEBUG)
175: printf(";; res_nquery: retry without EDNS0\n");
176: goto again;
177: }
178: #endif
179: #ifdef DEBUG
180: if (statp->options & RES_DEBUG)
181: printf(";; res_query: send error\n");
182: #endif
183: RES_SET_H_ERRNO(statp, TRY_AGAIN);
184: return (n);
185: }
186:
187: if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
188: #ifdef DEBUG
189: if (statp->options & RES_DEBUG)
190: printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
191: p_rcode(hp->rcode),
192: ntohs(hp->ancount),
193: ntohs(hp->nscount),
194: ntohs(hp->arcount));
195: #endif
196: switch (hp->rcode) {
197: case NXDOMAIN:
198: RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
199: break;
200: case SERVFAIL:
201: RES_SET_H_ERRNO(statp, TRY_AGAIN);
202: break;
203: case NOERROR:
204: RES_SET_H_ERRNO(statp, NO_DATA);
205: break;
206: case FORMERR:
207: case NOTIMP:
208: case REFUSED:
209: default:
210: RES_SET_H_ERRNO(statp, NO_RECOVERY);
211: break;
212: }
213: return (-1);
214: }
215: return (n);
216: }
217:
1.8 ! christos 218: /*%
1.1 christos 219: * Formulate a normal query, send, and retrieve answer in supplied buffer.
220: * Return the size of the response on success, -1 on error.
221: * If enabled, implement search rules until answer or unrecoverable failure
222: * is detected. Error code, if any, is left in H_ERRNO.
223: */
224: int
225: res_nsearch(res_state statp,
1.8 ! christos 226: const char *name, /*%< domain name */
! 227: int class, int type, /*%< class and type of query */
! 228: u_char *answer, /*%< buffer to put answer */
! 229: int anslen) /*%< size of answer */
1.1 christos 230: {
231: const char *cp, * const *domain;
1.2 christos 232: HEADER *hp = (HEADER *)(void *)answer;
1.1 christos 233: char tmp[NS_MAXDNAME];
234: u_int dots;
235: int trailing_dot, ret, saved_herrno;
236: int got_nodata = 0, got_servfail = 0, root_on_list = 0;
237: int tried_as_is = 0;
238: int searched = 0;
239:
240: errno = 0;
1.8 ! christos 241: RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
1.1 christos 242: dots = 0;
243: for (cp = name; *cp != '\0'; cp++)
244: dots += (*cp == '.');
245: trailing_dot = 0;
246: if (cp > name && *--cp == '.')
247: trailing_dot++;
248:
249: /* If there aren't any dots, it could be a user-level alias. */
250: if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
251: return (res_nquery(statp, cp, class, type, answer, anslen));
252:
253: /*
254: * If there are enough dots in the name, let's just give it a
255: * try 'as is'. The threshold can be set with the "ndots" option.
256: * Also, query 'as is', if there is a trailing dot in the name.
257: */
258: saved_herrno = -1;
259: if (dots >= statp->ndots || trailing_dot) {
260: ret = res_nquerydomain(statp, name, NULL, class, type,
261: answer, anslen);
262: if (ret > 0 || trailing_dot)
263: return (ret);
264: saved_herrno = statp->res_h_errno;
265: tried_as_is++;
266: }
267:
268: /*
269: * We do at least one level of search if
270: * - there is no dot and RES_DEFNAME is set, or
271: * - there is at least one dot, there is no trailing dot,
272: * and RES_DNSRCH is set.
273: */
274: if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
275: (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
276: int done = 0;
277:
278: for (domain = (const char * const *)statp->dnsrch;
279: *domain && !done;
280: domain++) {
281: searched = 1;
282:
283: if (domain[0][0] == '\0' ||
284: (domain[0][0] == '.' && domain[0][1] == '\0'))
285: root_on_list++;
286:
287: ret = res_nquerydomain(statp, name, *domain,
288: class, type,
289: answer, anslen);
290: if (ret > 0)
291: return (ret);
292:
293: /*
294: * If no server present, give up.
295: * If name isn't found in this domain,
296: * keep trying higher domains in the search list
297: * (if that's enabled).
298: * On a NO_DATA error, keep trying, otherwise
299: * a wildcard entry of another type could keep us
300: * from finding this entry higher in the domain.
301: * If we get some other error (negative answer or
302: * server failure), then stop searching up,
303: * but try the input name below in case it's
304: * fully-qualified.
305: */
306: if (errno == ECONNREFUSED) {
307: RES_SET_H_ERRNO(statp, TRY_AGAIN);
308: return (-1);
309: }
310:
311: switch (statp->res_h_errno) {
312: case NO_DATA:
313: got_nodata++;
314: /* FALLTHROUGH */
315: case HOST_NOT_FOUND:
316: /* keep trying */
317: break;
318: case TRY_AGAIN:
319: if (hp->rcode == SERVFAIL) {
320: /* try next search element, if any */
321: got_servfail++;
322: break;
323: }
324: /* FALLTHROUGH */
325: default:
326: /* anything else implies that we're done */
327: done++;
328: }
329:
330: /* if we got here for some reason other than DNSRCH,
331: * we only wanted one iteration of the loop, so stop.
332: */
333: if ((statp->options & RES_DNSRCH) == 0U)
334: done++;
335: }
336: }
337:
338: /*
339: * If the query has not already been tried as is then try it
340: * unless RES_NOTLDQUERY is set and there were no dots.
341: */
342: if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
343: !(tried_as_is || root_on_list)) {
344: ret = res_nquerydomain(statp, name, NULL, class, type,
345: answer, anslen);
346: if (ret > 0)
347: return (ret);
348: }
349:
350: /* if we got here, we didn't satisfy the search.
351: * if we did an initial full query, return that query's H_ERRNO
352: * (note that we wouldn't be here if that query had succeeded).
353: * else if we ever got a nodata, send that back as the reason.
354: * else send back meaningless H_ERRNO, that being the one from
355: * the last DNSRCH we did.
356: */
357: if (saved_herrno != -1)
358: RES_SET_H_ERRNO(statp, saved_herrno);
359: else if (got_nodata)
360: RES_SET_H_ERRNO(statp, NO_DATA);
361: else if (got_servfail)
362: RES_SET_H_ERRNO(statp, TRY_AGAIN);
363: return (-1);
364: }
365:
1.8 ! christos 366: /*%
1.1 christos 367: * Perform a call on res_query on the concatenation of name and domain,
368: * removing a trailing dot from name if domain is NULL.
369: */
370: int
371: res_nquerydomain(res_state statp,
372: const char *name,
373: const char *domain,
1.8 ! christos 374: int class, int type, /*%< class and type of query */
! 375: u_char *answer, /*%< buffer to put answer */
! 376: int anslen) /*%< size of answer */
1.1 christos 377: {
378: char nbuf[MAXDNAME];
379: const char *longname = nbuf;
380: int n, d;
381:
382: #ifdef DEBUG
383: if (statp->options & RES_DEBUG)
384: printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
385: name, domain?domain:"<Nil>", class, type);
386: #endif
387: if (domain == NULL) {
388: /*
389: * Check for trailing '.';
390: * copy without '.' if present.
391: */
392: n = strlen(name);
393: if (n >= MAXDNAME) {
394: RES_SET_H_ERRNO(statp, NO_RECOVERY);
395: return (-1);
396: }
397: n--;
398: if (n >= 0 && name[n] == '.') {
1.2 christos 399: strncpy(nbuf, name, (size_t)n);
1.1 christos 400: nbuf[n] = '\0';
401: } else
402: longname = name;
403: } else {
404: n = strlen(name);
405: d = strlen(domain);
406: if (n + d + 1 >= MAXDNAME) {
407: RES_SET_H_ERRNO(statp, NO_RECOVERY);
408: return (-1);
409: }
410: sprintf(nbuf, "%s.%s", name, domain);
411: }
412: return (res_nquery(statp, longname, class, type, answer, anslen));
413: }
414:
415: const char *
416: res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
417: char *file, *cp1, *cp2;
418: char buf[BUFSIZ];
419: FILE *fp;
420:
421: if (statp->options & RES_NOALIASES)
422: return (NULL);
1.6 christos 423: /*
424: * forbid hostaliases for setuid binary, due to possible security
425: * breach.
426: */
427: if (issetugid())
428: return (NULL);
1.1 christos 429: file = getenv("HOSTALIASES");
430: if (file == NULL || (fp = fopen(file, "r")) == NULL)
431: return (NULL);
432: setbuf(fp, NULL);
433: buf[sizeof(buf) - 1] = '\0';
434: while (fgets(buf, sizeof(buf), fp)) {
435: for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
436: ;
437: if (!*cp1)
438: break;
439: *cp1 = '\0';
440: if (ns_samename(buf, name) == 1) {
441: while (isspace((unsigned char)*++cp1))
442: ;
443: if (!*cp1)
444: break;
445: for (cp2 = cp1 + 1; *cp2 &&
446: !isspace((unsigned char)*cp2); ++cp2)
447: ;
448: *cp2 = '\0';
449: strncpy(dst, cp1, siz - 1);
450: dst[siz - 1] = '\0';
451: fclose(fp);
452: return (dst);
453: }
454: }
455: fclose(fp);
456: return (NULL);
457: }
1.8 ! christos 458:
! 459: /*! \file */
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