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 int h_errno;
62
63 /*
64 * Formulate a normal query, send, and await answer.
65 * Returned answer is placed in supplied buffer "answer".
66 * Perform preliminary check of answer, returning success only
67 * if no error is indicated and the answer count is nonzero.
68 * Return the size of the response on success, -1 on error.
69 * Error number is left in h_errno.
70 * Caller must parse answer and determine whether it answers the question.
71 */
72 int
73 res_query(name, class, type, answer, anslen)
74 char *name; /* domain name */
75 int class, type; /* class and type of query */
76 u_char *answer; /* buffer to put answer */
77 int anslen; /* size of answer buffer */
78 {
79 char buf[MAXPACKET];
80 HEADER *hp;
81 int n;
82
83 if ((_res.options & RES_INIT) == 0 && res_init() == -1)
84 return (-1);
85 #ifdef DEBUG
86 if (_res.options & RES_DEBUG)
87 printf("res_query(%s, %d, %d)\n", name, class, type);
88 #endif
89 n = res_mkquery(QUERY, name, class, type, (char *)NULL, 0, NULL,
90 buf, sizeof (buf));
91
92 if (n <= 0) {
93 #ifdef DEBUG
94 if (_res.options & RES_DEBUG)
95 printf("res_query: mkquery failed\n");
96 #endif
97 h_errno = NO_RECOVERY;
98 return (n);
99 }
100 n = res_send(buf, n, (char *)answer, anslen);
101 if (n < 0) {
102 #ifdef DEBUG
103 if (_res.options & RES_DEBUG)
104 printf("res_query: send error\n");
105 #endif
106 h_errno = TRY_AGAIN;
107 return (n);
108 }
109
110 hp = (HEADER *) answer;
111 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
112 #ifdef DEBUG
113 if (_res.options & RES_DEBUG)
114 printf("rcode = %d, ancount=%d\n", hp->rcode,
115 ntohs(hp->ancount));
116 #endif
117 switch (hp->rcode) {
118 case NXDOMAIN:
119 h_errno = HOST_NOT_FOUND;
120 break;
121 case SERVFAIL:
122 h_errno = TRY_AGAIN;
123 break;
124 case NOERROR:
125 h_errno = NO_DATA;
126 break;
127 case FORMERR:
128 case NOTIMP:
129 case REFUSED:
130 default:
131 h_errno = NO_RECOVERY;
132 break;
133 }
134 return (-1);
135 }
136 if (hp->rcode == NOERROR && ntohs(hp->ancount) > 0)
137 h_errno = 0;
138 return (n);
139 }
140
141 /*
142 * Formulate a normal query, send, and retrieve answer in supplied buffer.
143 * Return the size of the response on success, -1 on error.
144 * If enabled, implement search rules until answer or unrecoverable failure
145 * is detected. Error number is left in h_errno.
146 * Only useful for queries in the same name hierarchy as the local host
147 * (not, for example, for host address-to-name lookups in domain in-addr.arpa).
148 */
149 int
150 res_search(name, class, type, answer, anslen)
151 char *name; /* domain name */
152 int class, type; /* class and type of query */
153 u_char *answer; /* buffer to put answer */
154 int anslen; /* size of answer */
155 {
156 register char *cp, **domain;
157 int n, ret, got_nodata = 0;
158 char *hostalias();
159
160 if ((_res.options & RES_INIT) == 0 && res_init() == -1)
161 return (-1);
162
163 errno = 0;
164 h_errno = HOST_NOT_FOUND; /* default, if we never query */
165 for (cp = name, n = 0; *cp; cp++)
166 if (*cp == '.')
167 n++;
168 if (n == 0 && (cp = hostalias(name)))
169 return (res_query(cp, class, type, answer, anslen));
170
171 /*
172 * We do at least one level of search if
173 * - there is no dot and RES_DEFNAME is set, or
174 * - there is at least one dot, there is no trailing dot,
175 * and RES_DNSRCH is set.
176 */
177 if ((n == 0 && _res.options & RES_DEFNAMES) ||
178 (n != 0 && *--cp != '.' && _res.options & RES_DNSRCH)) {
179 for (domain = _res.dnsrch; *domain; domain++) {
180 ret = res_querydomain(name, *domain, class, type,
181 answer, anslen);
182 if (ret > 0)
183 return (ret);
184 /*
185 * If no server present, give up.
186 * If name isn't found in this domain,
187 * keep trying higher domains in the search list
188 * (if that's enabled).
189 * On a NO_DATA error, keep trying, otherwise
190 * a wildcard entry of another type could keep us
191 * from finding this entry higher in the domain.
192 * If we get some other error (negative answer or
193 * server failure), then stop searching up,
194 * but try the input name below in case it's fully-qualified.
195 */
196 if (errno == ECONNREFUSED) {
197 h_errno = TRY_AGAIN;
198 return (-1);
199 }
200 if (h_errno == NO_DATA)
201 got_nodata++;
202 if ((h_errno != HOST_NOT_FOUND && h_errno != NO_DATA) ||
203 (_res.options & RES_DNSRCH) == 0)
204 break;
205 }
206 }
207 /*
208 * If the search/default failed, try the name as fully-qualified,
209 * but only if it contained at least one dot (even trailing).
210 * This is purely a heuristic; we assume that any reasonable query
211 * about a top-level domain (for servers, SOA, etc) will not use
212 * res_search.
213 */
214 if (n && (ret = res_querydomain(name, (char *)NULL, class, type,
215 answer, anslen)) > 0)
216 return (ret);
217 if (got_nodata)
218 h_errno = NO_DATA;
219 return (-1);
220 }
221
222 /*
223 * Perform a call on res_query on the concatenation of name and domain,
224 * removing a trailing dot from name if domain is NULL.
225 */
226 int
227 res_querydomain(name, domain, class, type, answer, anslen)
228 char *name, *domain;
229 int class, type; /* class and type of query */
230 u_char *answer; /* buffer to put answer */
231 int anslen; /* size of answer */
232 {
233 char nbuf[2*MAXDNAME+2];
234 char *longname = nbuf;
235 int n;
236
237 #ifdef DEBUG
238 if (_res.options & RES_DEBUG) {
239 if (domain == (char *)NULL)
240 printf("res_querydomain(%s, NULL, %d, %d)\n",
241 name, class, type);
242 else
243 printf("res_querydomain(%s, %s, %d, %d)\n",
244 name, domain, class, type);
245 }
246 #endif
247 if (domain == NULL) {
248 /*
249 * Check for trailing '.';
250 * copy without '.' if present.
251 */
252 n = strlen(name) - 1;
253 if (name[n] == '.' && n < sizeof (nbuf) - 1) {
254 #ifdef SYSV
255 memcpy((void *)nbuf, (void *)name, n);
256 #else
257 bcopy(name, nbuf, n);
258 #endif
259 nbuf[n] = '\0';
260 } else
261 longname = name;
262 } else
263 (void) sprintf(nbuf, "%.*s.%.*s",
264 MAXDNAME, name, MAXDNAME, domain);
265
266 return (res_query(longname, class, type, answer, anslen));
267 }
268
269 char *
270 hostalias(name)
271 register char *name;
272 {
273 register char *C1, *C2;
274 FILE *fp;
275 char *file;
276 char buf[BUFSIZ];
277 static char abuf[MAXDNAME];
278
279 file = getenv("HOSTALIASES");
280 if (file == NULL || (fp = fopen(file, "r")) == NULL)
281 return (NULL);
282 buf[sizeof (buf) - 1] = '\0';
283 while (fgets(buf, sizeof (buf), fp)) {
284 for (C1 = buf; *C1 && !isspace(*C1); ++C1);
285 if (!*C1)
286 break;
287 *C1 = '\0';
288 if (!strcasecmp(buf, name)) {
289 while (isspace(*++C1));
290 if (!*C1)
291 break;
292 for (C2 = C1 + 1; *C2 && !isspace(*C2); ++C2);
293 abuf[sizeof (abuf) - 1] = *C2 = '\0';
294 (void) strncpy(abuf, C1, sizeof (abuf) - 1);
295 fclose(fp);
296 return (abuf);
297 }
298 }
299 fclose(fp);
300 return (NULL);
301 }