Annotation of src/lib/libc/resolv/res_query.c, Revision 1.1.1.3
1.1.1.3 ! ghen 1: /* $NetBSD$ */
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:
73: #if defined(LIBC_SCCS) && !defined(lint)
74: static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
1.1.1.2 christos 75: static const char rcsid[] = "Id: res_query.c,v 1.7.18.1 2005/04/27 05:01:11 sra Exp";
1.1 christos 76: #endif /* LIBC_SCCS and not lint */
77:
78: #include "port_before.h"
79: #include <sys/types.h>
80: #include <sys/param.h>
81: #include <netinet/in.h>
82: #include <arpa/inet.h>
83: #include <arpa/nameser.h>
84: #include <ctype.h>
85: #include <errno.h>
86: #include <netdb.h>
87: #include <resolv.h>
88: #include <stdio.h>
89: #include <stdlib.h>
90: #include <string.h>
91: #include "port_after.h"
92:
93: /* Options. Leave them on. */
94: #define DEBUG
95:
96: #if PACKETSZ > 1024
97: #define MAXPACKET PACKETSZ
98: #else
99: #define MAXPACKET 1024
100: #endif
101:
1.1.1.2 christos 102: /*%
1.1 christos 103: * Formulate a normal query, send, and await answer.
104: * Returned answer is placed in supplied buffer "answer".
105: * Perform preliminary check of answer, returning success only
106: * if no error is indicated and the answer count is nonzero.
107: * Return the size of the response on success, -1 on error.
108: * Error number is left in H_ERRNO.
109: *
110: * Caller must parse answer and determine whether it answers the question.
111: */
112: int
113: res_nquery(res_state statp,
1.1.1.2 christos 114: const char *name, /*%< domain name */
115: int class, int type, /*%< class and type of query */
116: u_char *answer, /*%< buffer to put answer */
117: int anslen) /*%< size of answer buffer */
1.1 christos 118: {
119: u_char buf[MAXPACKET];
120: HEADER *hp = (HEADER *) answer;
121: int n;
122: u_int oflags;
123:
124: oflags = statp->_flags;
125:
126: again:
1.1.1.2 christos 127: hp->rcode = NOERROR; /*%< default */
1.1 christos 128: #ifdef DEBUG
129: if (statp->options & RES_DEBUG)
130: printf(";; res_query(%s, %d, %d)\n", name, class, type);
131: #endif
132:
133: n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
134: buf, sizeof(buf));
135: #ifdef RES_USE_EDNS0
136: if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
137: (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U)
138: n = res_nopt(statp, n, buf, sizeof(buf), anslen);
139: #endif
140: if (n <= 0) {
141: #ifdef DEBUG
142: if (statp->options & RES_DEBUG)
143: printf(";; res_query: mkquery failed\n");
144: #endif
145: RES_SET_H_ERRNO(statp, NO_RECOVERY);
146: return (n);
147: }
148: n = res_nsend(statp, buf, n, answer, anslen);
149: if (n < 0) {
150: #ifdef RES_USE_EDNS0
151: /* if the query choked with EDNS0, retry without EDNS0 */
152: if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
153: ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
154: statp->_flags |= RES_F_EDNS0ERR;
155: if (statp->options & RES_DEBUG)
156: printf(";; res_nquery: retry without EDNS0\n");
157: goto again;
158: }
159: #endif
160: #ifdef DEBUG
161: if (statp->options & RES_DEBUG)
162: printf(";; res_query: send error\n");
163: #endif
164: RES_SET_H_ERRNO(statp, TRY_AGAIN);
165: return (n);
166: }
167:
168: if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
169: #ifdef DEBUG
170: if (statp->options & RES_DEBUG)
171: printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
172: p_rcode(hp->rcode),
173: ntohs(hp->ancount),
174: ntohs(hp->nscount),
175: ntohs(hp->arcount));
176: #endif
177: switch (hp->rcode) {
178: case NXDOMAIN:
179: RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
180: break;
181: case SERVFAIL:
182: RES_SET_H_ERRNO(statp, TRY_AGAIN);
183: break;
184: case NOERROR:
185: RES_SET_H_ERRNO(statp, NO_DATA);
186: break;
187: case FORMERR:
188: case NOTIMP:
189: case REFUSED:
190: default:
191: RES_SET_H_ERRNO(statp, NO_RECOVERY);
192: break;
193: }
194: return (-1);
195: }
196: return (n);
197: }
198:
1.1.1.2 christos 199: /*%
1.1 christos 200: * Formulate a normal query, send, and retrieve answer in supplied buffer.
201: * Return the size of the response on success, -1 on error.
202: * If enabled, implement search rules until answer or unrecoverable failure
203: * is detected. Error code, if any, is left in H_ERRNO.
204: */
205: int
206: res_nsearch(res_state statp,
1.1.1.2 christos 207: const char *name, /*%< domain name */
208: int class, int type, /*%< class and type of query */
209: u_char *answer, /*%< buffer to put answer */
210: int anslen) /*%< size of answer */
1.1 christos 211: {
212: const char *cp, * const *domain;
213: HEADER *hp = (HEADER *) answer;
214: char tmp[NS_MAXDNAME];
215: u_int dots;
216: int trailing_dot, ret, saved_herrno;
217: int got_nodata = 0, got_servfail = 0, root_on_list = 0;
218: int tried_as_is = 0;
219: int searched = 0;
220:
221: errno = 0;
1.1.1.2 christos 222: RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
1.1 christos 223: dots = 0;
224: for (cp = name; *cp != '\0'; cp++)
225: dots += (*cp == '.');
226: trailing_dot = 0;
227: if (cp > name && *--cp == '.')
228: trailing_dot++;
229:
230: /* If there aren't any dots, it could be a user-level alias. */
231: if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
232: return (res_nquery(statp, cp, class, type, answer, anslen));
233:
234: /*
235: * If there are enough dots in the name, let's just give it a
236: * try 'as is'. The threshold can be set with the "ndots" option.
237: * Also, query 'as is', if there is a trailing dot in the name.
238: */
239: saved_herrno = -1;
240: if (dots >= statp->ndots || trailing_dot) {
241: ret = res_nquerydomain(statp, name, NULL, class, type,
242: answer, anslen);
243: if (ret > 0 || trailing_dot)
244: return (ret);
245: saved_herrno = statp->res_h_errno;
246: tried_as_is++;
247: }
248:
249: /*
250: * We do at least one level of search if
251: * - there is no dot and RES_DEFNAME is set, or
252: * - there is at least one dot, there is no trailing dot,
253: * and RES_DNSRCH is set.
254: */
255: if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
256: (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
257: int done = 0;
258:
259: for (domain = (const char * const *)statp->dnsrch;
260: *domain && !done;
261: domain++) {
262: searched = 1;
263:
264: if (domain[0][0] == '\0' ||
265: (domain[0][0] == '.' && domain[0][1] == '\0'))
266: root_on_list++;
267:
268: ret = res_nquerydomain(statp, name, *domain,
269: class, type,
270: answer, anslen);
271: if (ret > 0)
272: return (ret);
273:
274: /*
275: * If no server present, give up.
276: * If name isn't found in this domain,
277: * keep trying higher domains in the search list
278: * (if that's enabled).
279: * On a NO_DATA error, keep trying, otherwise
280: * a wildcard entry of another type could keep us
281: * from finding this entry higher in the domain.
282: * If we get some other error (negative answer or
283: * server failure), then stop searching up,
284: * but try the input name below in case it's
285: * fully-qualified.
286: */
287: if (errno == ECONNREFUSED) {
288: RES_SET_H_ERRNO(statp, TRY_AGAIN);
289: return (-1);
290: }
291:
292: switch (statp->res_h_errno) {
293: case NO_DATA:
294: got_nodata++;
295: /* FALLTHROUGH */
296: case HOST_NOT_FOUND:
297: /* keep trying */
298: break;
299: case TRY_AGAIN:
300: if (hp->rcode == SERVFAIL) {
301: /* try next search element, if any */
302: got_servfail++;
303: break;
304: }
305: /* FALLTHROUGH */
306: default:
307: /* anything else implies that we're done */
308: done++;
309: }
310:
311: /* if we got here for some reason other than DNSRCH,
312: * we only wanted one iteration of the loop, so stop.
313: */
314: if ((statp->options & RES_DNSRCH) == 0U)
315: done++;
316: }
317: }
318:
319: /*
320: * If the query has not already been tried as is then try it
321: * unless RES_NOTLDQUERY is set and there were no dots.
322: */
323: if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
324: !(tried_as_is || root_on_list)) {
325: ret = res_nquerydomain(statp, name, NULL, class, type,
326: answer, anslen);
327: if (ret > 0)
328: return (ret);
329: }
330:
331: /* if we got here, we didn't satisfy the search.
332: * if we did an initial full query, return that query's H_ERRNO
333: * (note that we wouldn't be here if that query had succeeded).
334: * else if we ever got a nodata, send that back as the reason.
335: * else send back meaningless H_ERRNO, that being the one from
336: * the last DNSRCH we did.
337: */
338: if (saved_herrno != -1)
339: RES_SET_H_ERRNO(statp, saved_herrno);
340: else if (got_nodata)
341: RES_SET_H_ERRNO(statp, NO_DATA);
342: else if (got_servfail)
343: RES_SET_H_ERRNO(statp, TRY_AGAIN);
344: return (-1);
345: }
346:
1.1.1.2 christos 347: /*%
1.1 christos 348: * Perform a call on res_query on the concatenation of name and domain,
349: * removing a trailing dot from name if domain is NULL.
350: */
351: int
352: res_nquerydomain(res_state statp,
353: const char *name,
354: const char *domain,
1.1.1.2 christos 355: int class, int type, /*%< class and type of query */
356: u_char *answer, /*%< buffer to put answer */
357: int anslen) /*%< size of answer */
1.1 christos 358: {
359: char nbuf[MAXDNAME];
360: const char *longname = nbuf;
361: int n, d;
362:
363: #ifdef DEBUG
364: if (statp->options & RES_DEBUG)
365: printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
366: name, domain?domain:"<Nil>", class, type);
367: #endif
368: if (domain == NULL) {
369: /*
370: * Check for trailing '.';
371: * copy without '.' if present.
372: */
373: n = strlen(name);
374: if (n >= MAXDNAME) {
375: RES_SET_H_ERRNO(statp, NO_RECOVERY);
376: return (-1);
377: }
378: n--;
379: if (n >= 0 && name[n] == '.') {
380: strncpy(nbuf, name, n);
381: nbuf[n] = '\0';
382: } else
383: longname = name;
384: } else {
385: n = strlen(name);
386: d = strlen(domain);
387: if (n + d + 1 >= MAXDNAME) {
388: RES_SET_H_ERRNO(statp, NO_RECOVERY);
389: return (-1);
390: }
391: sprintf(nbuf, "%s.%s", name, domain);
392: }
393: return (res_nquery(statp, longname, class, type, answer, anslen));
394: }
395:
396: const char *
397: res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
398: char *file, *cp1, *cp2;
399: char buf[BUFSIZ];
400: FILE *fp;
401:
402: if (statp->options & RES_NOALIASES)
403: return (NULL);
404: file = getenv("HOSTALIASES");
405: if (file == NULL || (fp = fopen(file, "r")) == NULL)
406: return (NULL);
407: setbuf(fp, NULL);
408: buf[sizeof(buf) - 1] = '\0';
409: while (fgets(buf, sizeof(buf), fp)) {
410: for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
411: ;
412: if (!*cp1)
413: break;
414: *cp1 = '\0';
415: if (ns_samename(buf, name) == 1) {
416: while (isspace((unsigned char)*++cp1))
417: ;
418: if (!*cp1)
419: break;
420: for (cp2 = cp1 + 1; *cp2 &&
421: !isspace((unsigned char)*cp2); ++cp2)
422: ;
423: *cp2 = '\0';
424: strncpy(dst, cp1, siz - 1);
425: dst[siz - 1] = '\0';
426: fclose(fp);
427: return (dst);
428: }
429: }
430: fclose(fp);
431: return (NULL);
432: }
1.1.1.2 christos 433:
434: /*! \file */
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