1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
28 /* All Rights Reserved */
29
30 /*
31 * University Copyright- Copyright (c) 1982, 1986, 1988
32 * The Regents of the University of California
33 * All Rights Reserved
34 *
35 * University Acknowledgment- Portions of this document are derived from
36 * software developed by the University of California, Berkeley, and its
37 * contributors.
38 */
39
40 #pragma ident "%Z%%M% %I% %E% SMI"
41
42 #include <sys/param.h>
43 #include <sys/socket.h>
44 #include <netinet/in.h>
45 #include <ctype.h>
46 #include <netdb.h>
47 #include <stdio.h>
48 #include <errno.h>
49 #include <string.h>
50 #include <arpa/inet.h>
51 #include <arpa/nameser.h>
52 #include <resolv.h>
53
54 #if PACKETSZ > 1024
55 #define MAXPACKET PACKETSZ
56 #else
57 #define MAXPACKET 1024
58 #endif
59
60 int h_errno;
61
62 /*
63 * Formulate a normal query, send, and await answer.
64 * Returned answer is placed in supplied buffer "answer".
65 * Perform preliminary check of answer, returning success only
66 * if no error is indicated and the answer count is nonzero.
67 * Return the size of the response on success, -1 on error.
68 * Error number is left in h_errno.
69 * Caller must parse answer and determine whether it answers the question.
70 */
71 int
72 res_query(name, class, type, answer, anslen)
73 char *name; /* domain name */
74 int class, type; /* class and type of query */
75 u_char *answer; /* buffer to put answer */
76 int anslen; /* size of answer buffer */
77 {
78 char buf[MAXPACKET];
79 HEADER *hp;
80 int n;
81
82 if ((_res.options & RES_INIT) == 0 && res_init() == -1)
83 return (-1);
84 #ifdef DEBUG
85 if (_res.options & RES_DEBUG)
86 printf("res_query(%s, %d, %d)\n", name, class, type);
87 #endif
88 n = res_mkquery(QUERY, name, class, type, (char *)NULL, 0, NULL,
89 buf, sizeof (buf));
90
91 if (n <= 0) {
92 #ifdef DEBUG
93 if (_res.options & RES_DEBUG)
94 printf("res_query: mkquery failed\n");
95 #endif
96 h_errno = NO_RECOVERY;
97 return (n);
98 }
99 n = res_send(buf, n, answer, anslen);
100 if (n < 0) {
101 #ifdef DEBUG
102 if (_res.options & RES_DEBUG)
103 printf("res_query: send error\n");
104 #endif
105 h_errno = TRY_AGAIN;
106 return (n);
107 }
108
109 hp = (HEADER *) answer;
110 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
111 #ifdef DEBUG
112 if (_res.options & RES_DEBUG)
113 printf("rcode = %d, ancount=%d\n", hp->rcode,
114 ntohs(hp->ancount));
115 #endif
116 switch (hp->rcode) {
117 case NXDOMAIN:
118 h_errno = HOST_NOT_FOUND;
119 break;
120 case SERVFAIL:
121 h_errno = TRY_AGAIN;
122 break;
123 case NOERROR:
124 h_errno = NO_DATA;
125 break;
126 case FORMERR:
127 case NOTIMP:
128 case REFUSED:
129 default:
130 h_errno = NO_RECOVERY;
131 break;
132 }
133 return (-1);
134 }
135 if (hp->rcode == NOERROR && ntohs(hp->ancount) > 0)
136 h_errno = 0;
137 return (n);
138 }
139
140 /*
141 * Formulate a normal query, send, and retrieve answer in supplied buffer.
142 * Return the size of the response on success, -1 on error.
143 * If enabled, implement search rules until answer or unrecoverable failure
144 * is detected. Error number is left in h_errno.
145 * Only useful for queries in the same name hierarchy as the local host
146 * (not, for example, for host address-to-name lookups in domain in-addr.arpa).
147 */
148 int
149 res_search(name, class, type, answer, anslen)
150 char *name; /* domain name */
151 int class, type; /* class and type of query */
152 u_char *answer; /* buffer to put answer */
153 int anslen; /* size of answer */
154 {
155 register char *cp, **domain;
156 int n, ret, got_nodata = 0;
157 char *hostalias();
158
159 if ((_res.options & RES_INIT) == 0 && res_init() == -1)
160 return (-1);
161
162 errno = 0;
163 h_errno = HOST_NOT_FOUND; /* default, if we never query */
164 for (cp = name, n = 0; *cp; cp++)
165 if (*cp == '.')
166 n++;
167 if (n == 0 && (cp = hostalias(name)))
168 return (res_query(cp, class, type, answer, anslen));
169
170 /*
171 * We do at least one level of search if
172 * - there is no dot and RES_DEFNAME is set, or
173 * - there is at least one dot, there is no trailing dot,
174 * and RES_DNSRCH is set.
175 */
176 if ((n == 0 && _res.options & RES_DEFNAMES) ||
177 (n != 0 && *--cp != '.' && _res.options & RES_DNSRCH)) {
178 for (domain = _res.dnsrch; *domain; domain++) {
179 ret = res_querydomain(name, *domain, class, type,
180 answer, anslen);
181 if (ret > 0)
182 return (ret);
183 /*
184 * If no server present, give up.
185 * If name isn't found in this domain,
186 * keep trying higher domains in the search list
187 * (if that's enabled).
188 * On a NO_DATA error, keep trying, otherwise
189 * a wildcard entry of another type could keep us
190 * from finding this entry higher in the domain.
191 * If we get some other error (negative answer or
192 * server failure), then stop searching up,
193 * but try the input name below in case it's fully-qualified.
194 */
195 if (errno == ECONNREFUSED) {
196 h_errno = TRY_AGAIN;
197 return (-1);
198 }
199 if (h_errno == NO_DATA)
200 got_nodata++;
201 if ((h_errno != HOST_NOT_FOUND && h_errno != NO_DATA) ||
202 (_res.options & RES_DNSRCH) == 0)
203 break;
204 }
205 }
206 /*
207 * If the search/default failed, try the name as fully-qualified,
208 * but only if it contained at least one dot (even trailing).
209 * This is purely a heuristic; we assume that any reasonable query
210 * about a top-level domain (for servers, SOA, etc) will not use
211 * res_search.
212 */
213 if (n && (ret = res_querydomain(name, (char *)NULL, class, type,
214 answer, anslen)) > 0)
215 return (ret);
216 if (got_nodata)
217 h_errno = NO_DATA;
218 return (-1);
219 }
220
221 /*
222 * Perform a call on res_query on the concatenation of name and domain,
223 * removing a trailing dot from name if domain is NULL.
224 */
225 int
226 res_querydomain(name, domain, class, type, answer, anslen)
227 char *name, *domain;
228 int class, type; /* class and type of query */
229 u_char *answer; /* buffer to put answer */
230 int anslen; /* size of answer */
231 {
232 char nbuf[2*MAXDNAME+2];
233 char *longname = nbuf;
234 int n;
235
236 #ifdef DEBUG
237 if (_res.options & RES_DEBUG) {
238 if (domain == (char *)NULL)
239 printf("res_querydomain(%s, NULL, %d, %d)\n",
240 name, class, type);
241 else
242 printf("res_querydomain(%s, %s, %d, %d)\n",
243 name, domain, class, type);
244 }
245 #endif
246 if (domain == NULL) {
247 /*
248 * Check for trailing '.';
249 * copy without '.' if present.
250 */
251 n = strlen(name) - 1;
252 if (name[n] == '.' && n < sizeof (nbuf) - 1) {
253 #ifdef SYSV
254 memcpy((void *)nbuf, (void *)name, n);
255 #else
256 bcopy(name, nbuf, n);
257 #endif
258 nbuf[n] = '\0';
259 } else
260 longname = name;
261 } else
262 (void) sprintf(nbuf, "%.*s.%.*s",
263 MAXDNAME, name, MAXDNAME, domain);
264
265 return (res_query(longname, class, type, answer, anslen));
266 }
267
268 char *
269 hostalias(name)
270 register char *name;
271 {
272 register char *C1, *C2;
273 FILE *fp;
274 char *file, *getenv(), *strcpy(), *strncpy();
275 char buf[BUFSIZ];
276 static char abuf[MAXDNAME];
277
278 file = getenv("HOSTALIASES");
279 if (file == NULL || (fp = fopen(file, "r")) == NULL)
280 return (NULL);
281 buf[sizeof (buf) - 1] = '\0';
282 while (fgets(buf, sizeof (buf), fp)) {
283 for (C1 = buf; *C1 && !isspace(*C1); ++C1);
284 if (!*C1)
285 break;
286 *C1 = '\0';
287 if (!strcasecmp(buf, name)) {
288 while (isspace(*++C1));
289 if (!*C1)
290 break;
291 for (C2 = C1 + 1; *C2 && !isspace(*C2); ++C2);
292 abuf[sizeof (abuf) - 1] = *C2 = '\0';
293 (void) strncpy(abuf, C1, sizeof (abuf) - 1);
294 fclose(fp);
295 return (abuf);
296 }
297 }
298 fclose(fp);
299 return (NULL);
300 }