Annotation of src/lib/libc/resolv/res_query.c, Revision 1.14
1.14 ! christos 1: /* $NetBSD: res_query.c,v 1.13 2009/10/24 21:37:57 christos Exp $ */
1.12 christos 2:
3: /*
4: * Portions Copyright (C) 2004, 2005, 2008 Internet Systems Consortium, Inc. ("ISC")
5: * Portions Copyright (C) 1996-2001, 2003 Internet Software Consortium.
6: *
7: * Permission to use, copy, modify, and/or distribute this software for any
8: * purpose with or without fee is hereby granted, provided that the above
9: * copyright notice and this permission notice appear in all copies.
10: *
11: * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
12: * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
13: * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
14: * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
15: * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
16: * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
17: * PERFORMANCE OF THIS SOFTWARE.
18: */
1.1 christos 19:
20: /*
21: * Copyright (c) 1988, 1993
22: * The Regents of the University of California. All rights reserved.
1.12 christos 23: *
1.1 christos 24: * Redistribution and use in source and binary forms, with or without
25: * modification, are permitted provided that the following conditions
26: * are met:
27: * 1. Redistributions of source code must retain the above copyright
28: * notice, this list of conditions and the following disclaimer.
29: * 2. Redistributions in binary form must reproduce the above copyright
30: * notice, this list of conditions and the following disclaimer in the
31: * documentation and/or other materials provided with the distribution.
32: * 3. All advertising materials mentioning features or use of this software
33: * must display the following acknowledgement:
34: * This product includes software developed by the University of
35: * California, Berkeley and its contributors.
36: * 4. Neither the name of the University nor the names of its contributors
37: * may be used to endorse or promote products derived from this software
38: * without specific prior written permission.
1.12 christos 39: *
1.1 christos 40: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
41: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
44: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50: * SUCH DAMAGE.
51: */
52:
53: /*
54: * Portions Copyright (c) 1993 by Digital Equipment Corporation.
1.12 christos 55: *
1.1 christos 56: * Permission to use, copy, modify, and distribute this software for any
57: * purpose with or without fee is hereby granted, provided that the above
58: * copyright notice and this permission notice appear in all copies, and that
59: * the name of Digital Equipment Corporation not be used in advertising or
60: * publicity pertaining to distribution of the document or software without
61: * specific, written prior permission.
1.12 christos 62: *
1.1 christos 63: * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
64: * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
65: * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
66: * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
67: * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
68: * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
69: * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
70: * SOFTWARE.
71: */
72:
73: /*
74: * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
75: * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
76: *
77: * Permission to use, copy, modify, and distribute this software for any
78: * purpose with or without fee is hereby granted, provided that the above
79: * copyright notice and this permission notice appear in all copies.
80: *
81: * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
82: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
83: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
84: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
85: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
86: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
87: * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
88: */
89:
1.3 christos 90: #include <sys/cdefs.h>
1.1 christos 91: #if defined(LIBC_SCCS) && !defined(lint)
1.3 christos 92: #ifdef notdef
1.1 christos 93: static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
1.12 christos 94: static const char rcsid[] = "Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp";
1.3 christos 95: #else
1.14 ! christos 96: __RCSID("$NetBSD: res_query.c,v 1.13 2009/10/24 21:37:57 christos Exp $");
1.3 christos 97: #endif
1.1 christos 98: #endif /* LIBC_SCCS and not lint */
99:
100: #include "port_before.h"
1.4 christos 101:
102: #include "namespace.h"
1.1 christos 103: #include <sys/types.h>
104: #include <sys/param.h>
105: #include <netinet/in.h>
106: #include <arpa/inet.h>
107: #include <arpa/nameser.h>
108: #include <ctype.h>
109: #include <errno.h>
110: #include <netdb.h>
111: #include <resolv.h>
112: #include <stdio.h>
113: #include <stdlib.h>
1.6 christos 114: #include <unistd.h>
1.1 christos 115: #include <string.h>
116: #include "port_after.h"
117:
1.5 christos 118: #if 0
1.4 christos 119: #ifdef __weak_alias
120: __weak_alias(res_nquery,_res_nquery)
121: __weak_alias(res_nsearch,_res_nsearch)
122: __weak_alias(res_nquerydomain,__res_nquerydomain)
123: __weak_alias(res_hostalias,__res_hostalias)
124: #endif
1.5 christos 125: #endif
1.4 christos 126:
1.1 christos 127: /* Options. Leave them on. */
1.11 christos 128: #ifndef DEBUG
1.1 christos 129: #define DEBUG
1.11 christos 130: #endif
1.1 christos 131:
132: #if PACKETSZ > 1024
133: #define MAXPACKET PACKETSZ
134: #else
135: #define MAXPACKET 1024
136: #endif
137:
1.8 christos 138: /*%
1.1 christos 139: * Formulate a normal query, send, and await answer.
140: * Returned answer is placed in supplied buffer "answer".
141: * Perform preliminary check of answer, returning success only
142: * if no error is indicated and the answer count is nonzero.
143: * Return the size of the response on success, -1 on error.
144: * Error number is left in H_ERRNO.
145: *
146: * Caller must parse answer and determine whether it answers the question.
147: */
148: int
149: res_nquery(res_state statp,
1.8 christos 150: const char *name, /*%< domain name */
151: int class, int type, /*%< class and type of query */
152: u_char *answer, /*%< buffer to put answer */
153: int anslen) /*%< size of answer buffer */
1.1 christos 154: {
155: u_char buf[MAXPACKET];
1.2 christos 156: HEADER *hp = (HEADER *)(void *)answer;
1.1 christos 157: u_int oflags;
1.10 christos 158: u_char *rdata;
1.12 christos 159: int n;
1.1 christos 160:
161: oflags = statp->_flags;
162:
163: again:
1.8 christos 164: hp->rcode = NOERROR; /*%< default */
1.1 christos 165: #ifdef DEBUG
166: if (statp->options & RES_DEBUG)
167: printf(";; res_query(%s, %d, %d)\n", name, class, type);
168: #endif
169:
170: n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
1.14 ! christos 171: buf, (int)sizeof(buf));
1.1 christos 172: #ifdef RES_USE_EDNS0
173: if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
1.10 christos 174: (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID)) != 0U) {
1.14 ! christos 175: n = res_nopt(statp, n, buf, (int)sizeof(buf), anslen);
1.10 christos 176: rdata = &buf[n];
177: if (n > 0 && (statp->options & RES_NSID) != 0U) {
1.14 ! christos 178: n = res_nopt_rdata(statp, n, buf, (int)sizeof(buf),
! 179: rdata, NS_OPT_NSID, 0, NULL);
1.10 christos 180: }
181: }
1.1 christos 182: #endif
183: if (n <= 0) {
184: #ifdef DEBUG
185: if (statp->options & RES_DEBUG)
186: printf(";; res_query: mkquery failed\n");
187: #endif
188: RES_SET_H_ERRNO(statp, NO_RECOVERY);
189: return (n);
190: }
1.10 christos 191:
1.1 christos 192: n = res_nsend(statp, buf, n, answer, anslen);
193: if (n < 0) {
194: #ifdef RES_USE_EDNS0
195: /* if the query choked with EDNS0, retry without EDNS0 */
196: if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
197: ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
198: statp->_flags |= RES_F_EDNS0ERR;
199: if (statp->options & RES_DEBUG)
200: printf(";; res_nquery: retry without EDNS0\n");
201: goto again;
202: }
203: #endif
204: #ifdef DEBUG
205: if (statp->options & RES_DEBUG)
206: printf(";; res_query: send error\n");
207: #endif
208: RES_SET_H_ERRNO(statp, TRY_AGAIN);
209: return (n);
210: }
211:
212: if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
213: #ifdef DEBUG
214: if (statp->options & RES_DEBUG)
215: printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
216: p_rcode(hp->rcode),
217: ntohs(hp->ancount),
218: ntohs(hp->nscount),
219: ntohs(hp->arcount));
220: #endif
221: switch (hp->rcode) {
222: case NXDOMAIN:
223: RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
224: break;
225: case SERVFAIL:
226: RES_SET_H_ERRNO(statp, TRY_AGAIN);
227: break;
228: case NOERROR:
229: RES_SET_H_ERRNO(statp, NO_DATA);
230: break;
231: case FORMERR:
232: case NOTIMP:
233: case REFUSED:
234: default:
235: RES_SET_H_ERRNO(statp, NO_RECOVERY);
236: break;
237: }
238: return (-1);
239: }
240: return (n);
241: }
242:
1.8 christos 243: /*%
1.1 christos 244: * Formulate a normal query, send, and retrieve answer in supplied buffer.
245: * Return the size of the response on success, -1 on error.
246: * If enabled, implement search rules until answer or unrecoverable failure
247: * is detected. Error code, if any, is left in H_ERRNO.
248: */
249: int
250: res_nsearch(res_state statp,
1.8 christos 251: const char *name, /*%< domain name */
252: int class, int type, /*%< class and type of query */
253: u_char *answer, /*%< buffer to put answer */
254: int anslen) /*%< size of answer */
1.1 christos 255: {
256: const char *cp, * const *domain;
1.2 christos 257: HEADER *hp = (HEADER *)(void *)answer;
1.1 christos 258: char tmp[NS_MAXDNAME];
259: u_int dots;
260: int trailing_dot, ret, saved_herrno;
261: int got_nodata = 0, got_servfail = 0, root_on_list = 0;
262: int tried_as_is = 0;
263: int searched = 0;
264:
265: errno = 0;
1.8 christos 266: RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
1.1 christos 267: dots = 0;
268: for (cp = name; *cp != '\0'; cp++)
269: dots += (*cp == '.');
270: trailing_dot = 0;
271: if (cp > name && *--cp == '.')
272: trailing_dot++;
273:
274: /* If there aren't any dots, it could be a user-level alias. */
275: if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
276: return (res_nquery(statp, cp, class, type, answer, anslen));
277:
278: /*
279: * If there are enough dots in the name, let's just give it a
280: * try 'as is'. The threshold can be set with the "ndots" option.
281: * Also, query 'as is', if there is a trailing dot in the name.
282: */
283: saved_herrno = -1;
284: if (dots >= statp->ndots || trailing_dot) {
285: ret = res_nquerydomain(statp, name, NULL, class, type,
286: answer, anslen);
287: if (ret > 0 || trailing_dot)
288: return (ret);
289: saved_herrno = statp->res_h_errno;
290: tried_as_is++;
291: }
292:
293: /*
294: * We do at least one level of search if
295: * - there is no dot and RES_DEFNAME is set, or
296: * - there is at least one dot, there is no trailing dot,
297: * and RES_DNSRCH is set.
298: */
299: if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
300: (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
301: int done = 0;
302:
303: for (domain = (const char * const *)statp->dnsrch;
304: *domain && !done;
305: domain++) {
306: searched = 1;
307:
308: if (domain[0][0] == '\0' ||
309: (domain[0][0] == '.' && domain[0][1] == '\0'))
310: root_on_list++;
311:
312: ret = res_nquerydomain(statp, name, *domain,
313: class, type,
314: answer, anslen);
315: if (ret > 0)
316: return (ret);
317:
318: /*
319: * If no server present, give up.
320: * If name isn't found in this domain,
321: * keep trying higher domains in the search list
322: * (if that's enabled).
323: * On a NO_DATA error, keep trying, otherwise
324: * a wildcard entry of another type could keep us
325: * from finding this entry higher in the domain.
326: * If we get some other error (negative answer or
327: * server failure), then stop searching up,
328: * but try the input name below in case it's
329: * fully-qualified.
330: */
331: if (errno == ECONNREFUSED) {
332: RES_SET_H_ERRNO(statp, TRY_AGAIN);
333: return (-1);
334: }
335:
336: switch (statp->res_h_errno) {
337: case NO_DATA:
338: got_nodata++;
339: /* FALLTHROUGH */
340: case HOST_NOT_FOUND:
341: /* keep trying */
342: break;
343: case TRY_AGAIN:
344: if (hp->rcode == SERVFAIL) {
345: /* try next search element, if any */
346: got_servfail++;
347: break;
348: }
349: /* FALLTHROUGH */
350: default:
351: /* anything else implies that we're done */
352: done++;
353: }
354:
355: /* if we got here for some reason other than DNSRCH,
356: * we only wanted one iteration of the loop, so stop.
357: */
358: if ((statp->options & RES_DNSRCH) == 0U)
359: done++;
360: }
361: }
362:
363: /*
364: * If the query has not already been tried as is then try it
365: * unless RES_NOTLDQUERY is set and there were no dots.
366: */
367: if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
368: !(tried_as_is || root_on_list)) {
369: ret = res_nquerydomain(statp, name, NULL, class, type,
370: answer, anslen);
371: if (ret > 0)
372: return (ret);
373: }
374:
375: /* if we got here, we didn't satisfy the search.
376: * if we did an initial full query, return that query's H_ERRNO
377: * (note that we wouldn't be here if that query had succeeded).
378: * else if we ever got a nodata, send that back as the reason.
379: * else send back meaningless H_ERRNO, that being the one from
380: * the last DNSRCH we did.
381: */
382: if (saved_herrno != -1)
383: RES_SET_H_ERRNO(statp, saved_herrno);
384: else if (got_nodata)
385: RES_SET_H_ERRNO(statp, NO_DATA);
386: else if (got_servfail)
387: RES_SET_H_ERRNO(statp, TRY_AGAIN);
388: return (-1);
389: }
390:
1.8 christos 391: /*%
1.1 christos 392: * Perform a call on res_query on the concatenation of name and domain,
393: * removing a trailing dot from name if domain is NULL.
394: */
395: int
396: res_nquerydomain(res_state statp,
397: const char *name,
398: const char *domain,
1.8 christos 399: int class, int type, /*%< class and type of query */
400: u_char *answer, /*%< buffer to put answer */
401: int anslen) /*%< size of answer */
1.1 christos 402: {
403: char nbuf[MAXDNAME];
404: const char *longname = nbuf;
1.14 ! christos 405: size_t n, d;
1.1 christos 406:
407: #ifdef DEBUG
408: if (statp->options & RES_DEBUG)
409: printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
410: name, domain?domain:"<Nil>", class, type);
411: #endif
412: if (domain == NULL) {
413: /*
414: * Check for trailing '.';
415: * copy without '.' if present.
416: */
417: n = strlen(name);
418: if (n >= MAXDNAME) {
419: RES_SET_H_ERRNO(statp, NO_RECOVERY);
420: return (-1);
421: }
1.14 ! christos 422: if (n && name[--n] == '.') {
! 423: strncpy(nbuf, name, n);
1.1 christos 424: nbuf[n] = '\0';
425: } else
426: longname = name;
427: } else {
428: n = strlen(name);
429: d = strlen(domain);
430: if (n + d + 1 >= MAXDNAME) {
431: RES_SET_H_ERRNO(statp, NO_RECOVERY);
432: return (-1);
433: }
434: sprintf(nbuf, "%s.%s", name, domain);
435: }
436: return (res_nquery(statp, longname, class, type, answer, anslen));
437: }
438:
439: const char *
440: res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
441: char *file, *cp1, *cp2;
442: char buf[BUFSIZ];
443: FILE *fp;
444:
445: if (statp->options & RES_NOALIASES)
446: return (NULL);
1.6 christos 447: /*
448: * forbid hostaliases for setuid binary, due to possible security
449: * breach.
450: */
451: if (issetugid())
452: return (NULL);
1.1 christos 453: file = getenv("HOSTALIASES");
454: if (file == NULL || (fp = fopen(file, "r")) == NULL)
455: return (NULL);
456: buf[sizeof(buf) - 1] = '\0';
1.14 ! christos 457: while (fgets(buf, (int)sizeof(buf), fp)) {
1.1 christos 458: for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
459: ;
460: if (!*cp1)
461: break;
462: *cp1 = '\0';
463: if (ns_samename(buf, name) == 1) {
464: while (isspace((unsigned char)*++cp1))
465: ;
466: if (!*cp1)
467: break;
468: for (cp2 = cp1 + 1; *cp2 &&
469: !isspace((unsigned char)*cp2); ++cp2)
470: ;
471: *cp2 = '\0';
472: strncpy(dst, cp1, siz - 1);
473: dst[siz - 1] = '\0';
474: fclose(fp);
475: return (dst);
476: }
477: }
478: fclose(fp);
479: return (NULL);
480: }
1.8 christos 481:
482: /*! \file */
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