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 2015 Gary Mills
24 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
25 * Use is subject to license terms.
26 */
27
28 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
29 /* All Rights Reserved */
30
31 /*
32 * University Copyright- Copyright (c) 1982, 1986, 1988
33 * The Regents of the University of California
34 * All Rights Reserved
35 *
36 * University Acknowledgment- Portions of this document are derived from
37 * software developed by the University of California, Berkeley, and its
38 * contributors.
39 */
40
41 #include <sys/param.h>
42 #include <sys/socket.h>
43 #include <netinet/in.h>
44 #include <ctype.h>
45 #include <netdb.h>
46 #include <stdio.h>
47 #include <errno.h>
48 #include <string.h>
49 #include <stdlib.h>
50 #include <arpa/inet.h>
51 #include <arpa/nameser.h>
52 #include <resolv.h>
53 #include "crossl.h"
54
55 #if PACKETSZ > 1024
56 #define MAXPACKET PACKETSZ
57 #else
58 #define MAXPACKET 1024
59 #endif
60
61 /*
62 * Formulate a normal query, send, and await answer.
63 * Returned answer is placed in supplied buffer "answer".
64 * Perform preliminary check of answer, returning success only
65 * if no error is indicated and the answer count is nonzero.
66 * Return the size of the response on success, -1 on error.
67 * Error number is left in h_errno.
68 * Caller must parse answer and determine whether it answers the question.
69 */
70 int
res_query(name,class,type,answer,anslen)71 res_query(name, class, type, answer, anslen)
72 char *name; /* domain name */
73 int class, type; /* class and type of query */
74 u_char *answer; /* buffer to put answer */
75 int anslen; /* size of answer buffer */
76 {
77 char buf[MAXPACKET];
78 HEADER *hp;
79 int n;
80
81 if ((_res.options & RES_INIT) == 0 && res_init() == -1)
82 return (-1);
83 #ifdef DEBUG
84 if (_res.options & RES_DEBUG)
85 printf("res_query(%s, %d, %d)\n", name, class, type);
86 #endif
87 n = res_mkquery(QUERY, name, class, type, (char *)NULL, 0, NULL,
88 buf, sizeof (buf));
89
90 if (n <= 0) {
91 #ifdef DEBUG
92 if (_res.options & RES_DEBUG)
93 printf("res_query: mkquery failed\n");
94 #endif
95 h_errno = NO_RECOVERY;
96 return (n);
97 }
98 n = res_send(buf, n, (char *)answer, anslen);
99 if (n < 0) {
100 #ifdef DEBUG
101 if (_res.options & RES_DEBUG)
102 printf("res_query: send error\n");
103 #endif
104 h_errno = TRY_AGAIN;
105 return (n);
106 }
107
108 hp = (HEADER *) answer;
109 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
110 #ifdef DEBUG
111 if (_res.options & RES_DEBUG)
112 printf("rcode = %d, ancount=%d\n", hp->rcode,
113 ntohs(hp->ancount));
114 #endif
115 switch (hp->rcode) {
116 case NXDOMAIN:
117 h_errno = HOST_NOT_FOUND;
118 break;
119 case SERVFAIL:
120 h_errno = TRY_AGAIN;
121 break;
122 case NOERROR:
123 h_errno = NO_DATA;
124 break;
125 case FORMERR:
126 case NOTIMP:
127 case REFUSED:
128 default:
129 h_errno = NO_RECOVERY;
130 break;
131 }
132 return (-1);
133 }
134 if (hp->rcode == NOERROR && ntohs(hp->ancount) > 0)
135 h_errno = 0;
136 return (n);
137 }
138
139 /*
140 * Formulate a normal query, send, and retrieve answer in supplied buffer.
141 * Return the size of the response on success, -1 on error.
142 * If enabled, implement search rules until answer or unrecoverable failure
143 * is detected. Error number is left in h_errno.
144 * Only useful for queries in the same name hierarchy as the local host
145 * (not, for example, for host address-to-name lookups in domain in-addr.arpa).
146 */
147 int
res_search(name,class,type,answer,anslen)148 res_search(name, class, type, answer, anslen)
149 char *name; /* domain name */
150 int class, type; /* class and type of query */
151 u_char *answer; /* buffer to put answer */
152 int anslen; /* size of answer */
153 {
154 register char *cp, **domain;
155 int n, ret, got_nodata = 0;
156 char *hostalias();
157
158 if ((_res.options & RES_INIT) == 0 && res_init() == -1)
159 return (-1);
160
161 errno = 0;
162 h_errno = HOST_NOT_FOUND; /* default, if we never query */
163 for (cp = name, n = 0; *cp; cp++)
164 if (*cp == '.')
165 n++;
166 if (n == 0 && (cp = hostalias(name)))
167 return (res_query(cp, class, type, answer, anslen));
168
169 /*
170 * We do at least one level of search if
171 * - there is no dot and RES_DEFNAME is set, or
172 * - there is at least one dot, there is no trailing dot,
173 * and RES_DNSRCH is set.
174 */
175 if ((n == 0 && _res.options & RES_DEFNAMES) ||
176 (n != 0 && *--cp != '.' && _res.options & RES_DNSRCH)) {
177 for (domain = _res.dnsrch; *domain; domain++) {
178 ret = res_querydomain(name, *domain, class, type,
179 answer, anslen);
180 if (ret > 0)
181 return (ret);
182 /*
183 * If no server present, give up.
184 * If name isn't found in this domain,
185 * keep trying higher domains in the search list
186 * (if that's enabled).
187 * On a NO_DATA error, keep trying, otherwise
188 * a wildcard entry of another type could keep us
189 * from finding this entry higher in the domain.
190 * If we get some other error (negative answer or
191 * server failure), then stop searching up,
192 * but try the input name below in case it's fully-qualified.
193 */
194 if (errno == ECONNREFUSED) {
195 h_errno = TRY_AGAIN;
196 return (-1);
197 }
198 if (h_errno == NO_DATA)
199 got_nodata++;
200 if ((h_errno != HOST_NOT_FOUND && h_errno != NO_DATA) ||
201 (_res.options & RES_DNSRCH) == 0)
202 break;
203 }
204 }
205 /*
206 * If the search/default failed, try the name as fully-qualified,
207 * but only if it contained at least one dot (even trailing).
208 * This is purely a heuristic; we assume that any reasonable query
209 * about a top-level domain (for servers, SOA, etc) will not use
210 * res_search.
211 */
212 if (n && (ret = res_querydomain(name, (char *)NULL, class, type,
213 answer, anslen)) > 0)
214 return (ret);
215 if (got_nodata)
216 h_errno = NO_DATA;
217 return (-1);
218 }
219
220 /*
221 * Perform a call on res_query on the concatenation of name and domain,
222 * removing a trailing dot from name if domain is NULL.
223 */
224 int
res_querydomain(name,domain,class,type,answer,anslen)225 res_querydomain(name, domain, class, type, answer, anslen)
226 char *name, *domain;
227 int class, type; /* class and type of query */
228 u_char *answer; /* buffer to put answer */
229 int anslen; /* size of answer */
230 {
231 char nbuf[2*MAXDNAME+2];
232 char *longname = nbuf;
233 int n;
234
235 #ifdef DEBUG
236 if (_res.options & RES_DEBUG) {
237 if (domain == (char *)NULL)
238 printf("res_querydomain(%s, NULL, %d, %d)\n",
239 name, class, type);
240 else
241 printf("res_querydomain(%s, %s, %d, %d)\n",
242 name, domain, class, type);
243 }
244 #endif
245 if (domain == NULL) {
246 /*
247 * Check for trailing '.';
248 * copy without '.' if present.
249 */
250 n = strlen(name) - 1;
251 if (name[n] == '.' && n < sizeof (nbuf) - 1) {
252 #ifdef SYSV
253 memcpy((void *)nbuf, (void *)name, n);
254 #else
255 bcopy(name, nbuf, n);
256 #endif
257 nbuf[n] = '\0';
258 } else
259 longname = name;
260 } else
261 (void) sprintf(nbuf, "%.*s.%.*s",
262 MAXDNAME, name, MAXDNAME, domain);
263
264 return (res_query(longname, class, type, answer, anslen));
265 }
266
267 char *
hostalias(name)268 hostalias(name)
269 register char *name;
270 {
271 register char *C1, *C2;
272 FILE *fp;
273 char *file;
274 char buf[BUFSIZ];
275 static char abuf[MAXDNAME];
276
277 file = getenv("HOSTALIASES");
278 if (file == NULL || (fp = fopen(file, "r")) == NULL)
279 return (NULL);
280 buf[sizeof (buf) - 1] = '\0';
281 while (fgets(buf, sizeof (buf), fp)) {
282 for (C1 = buf; *C1 && !isspace(*C1); ++C1);
283 if (!*C1)
284 break;
285 *C1 = '\0';
286 if (!strcasecmp(buf, name)) {
287 while (isspace(*++C1));
288 if (!*C1)
289 break;
290 for (C2 = C1 + 1; *C2 && !isspace(*C2); ++C2);
291 abuf[sizeof (abuf) - 1] = *C2 = '\0';
292 (void) strncpy(abuf, C1, sizeof (abuf) - 1);
293 fclose(fp);
294 return (abuf);
295 }
296 }
297 fclose(fp);
298 return (NULL);
299 }
300