1 /* $NetBSD: res_init.c,v 1.8 2006/03/19 03:10:08 christos Exp $ */
2
3 /*
4 * Copyright (c) 1985, 1989, 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 #define LOG_TAG "res_init"
74
75 #include <sys/param.h>
76 #include <sys/socket.h>
77 #include <sys/time.h>
78 #include <sys/types.h>
79
80 #include <arpa/inet.h>
81 #include <arpa/nameser.h>
82 #include <netinet/in.h>
83
84 #include <android-base/logging.h>
85 #include <ctype.h>
86 #include <errno.h>
87 #include <fcntl.h>
88 #include <netdb.h>
89 #include <stdio.h>
90 #include <stdlib.h>
91 #include <string.h>
92 #include <unistd.h>
93
94 #include "netd_resolv/resolv.h"
95 #include "res_state_ext.h"
96 #include "resolv_private.h"
97
98
99 static void res_setoptions(res_state, const char*, const char*);
100
101 /*
102 * Resolver state default settings.
103 */
104
105 /*
106 * Set up default settings. If the configuration file exist, the values
107 * there will have precedence. Otherwise, the server address is set to
108 * INADDR_ANY and the default domain name comes from the gethostname().
109 *
110 * An interrim version of this code (BIND 4.9, pre-4.4BSD) used 127.0.0.1
111 * rather than INADDR_ANY ("0.0.0.0") as the default name server address
112 * since it was noted that INADDR_ANY actually meant ``the first interface
113 * you "ifconfig"'d at boot time'' and if this was a SLIP or PPP interface,
114 * it had to be "up" in order for you to reach your own name server. It
115 * was later decided that since the recommended practice is to always
116 * install local static routes through 127.0.0.1 for all your network
117 * interfaces, that we could solve this problem without a code change.
118 *
119 * The configuration file should always be used, since it is the only way
120 * to specify a default domain. If you are running a server on your local
121 * machine, you should say "nameserver 0.0.0.0" or "nameserver 127.0.0.1"
122 * in the configuration file.
123 *
124 * Return 0 if completes successfully, -1 on error
125 */
res_ninit(res_state statp)126 int res_ninit(res_state statp) {
127 return res_vinit(statp, 0);
128 }
129
130 /* This function has to be reachable by res_data.c but not publicly. */
res_vinit(res_state statp,int preinit)131 int res_vinit(res_state statp, int preinit) {
132 char *cp, **pp;
133 char buf[BUFSIZ];
134 int nserv = 0; /* number of nameserver records read from file */
135 int havesearch = 0;
136 int dots;
137 sockaddr_union u[2];
138
139 if ((statp->options & RES_INIT) != 0U) res_ndestroy(statp);
140
141 if (!preinit) {
142 statp->netid = NETID_UNSET;
143 statp->options = RES_DEFAULT;
144 statp->id = arc4random_uniform(65536);
145 statp->_mark = MARK_UNSET;
146 }
147
148 memset(u, 0, sizeof(u));
149 u[nserv].sin.sin_addr.s_addr = INADDR_ANY;
150 u[nserv].sin.sin_family = AF_INET;
151 u[nserv].sin.sin_port = htons(NAMESERVER_PORT);
152 nserv++;
153 statp->nscount = 0;
154 statp->ndots = 1;
155 statp->_vcsock = -1;
156 statp->_flags = 0;
157 statp->_u._ext.nscount = 0;
158 statp->_u._ext.ext = (res_state_ext*) malloc(sizeof(*statp->_u._ext.ext));
159 statp->use_local_nameserver = false;
160 if (statp->_u._ext.ext != NULL) {
161 memset(statp->_u._ext.ext, 0, sizeof(*statp->_u._ext.ext));
162 statp->_u._ext.ext->nsaddrs[0].sin = statp->nsaddr;
163 strcpy(statp->_u._ext.ext->nsuffix, "ip6.arpa");
164 strcpy(statp->_u._ext.ext->nsuffix2, "ip6.int");
165 }
166 statp->nsort = 0;
167 res_setservers(statp, u, nserv);
168
169 if (statp->defdname[0] == 0 && gethostname(buf, sizeof(statp->defdname) - 1) == 0 &&
170 (cp = strchr(buf, '.')) != NULL)
171 strcpy(statp->defdname, cp + 1);
172
173 /* find components of local domain that might be searched */
174 if (havesearch == 0) {
175 pp = statp->dnsrch;
176 *pp++ = statp->defdname;
177 *pp = NULL;
178
179 dots = 0;
180 for (cp = statp->defdname; *cp; cp++) dots += (*cp == '.');
181
182 cp = statp->defdname;
183 while (pp < statp->dnsrch + MAXDFLSRCH) {
184 if (dots < LOCALDOMAINPARTS) break;
185 cp = strchr(cp, '.') + 1; /* we know there is one */
186 *pp++ = cp;
187 dots--;
188 }
189 *pp = NULL;
190 LOG(DEBUG) << __func__ << ": dnsrch list:";
191 for (pp = statp->dnsrch; *pp; pp++) LOG(DEBUG) << "\t" << *pp;
192 }
193
194 if ((cp = getenv("RES_OPTIONS")) != NULL) res_setoptions(statp, cp, "env");
195 if (nserv > 0) {
196 statp->nscount = nserv;
197 statp->options |= RES_INIT;
198 }
199 return (0);
200 }
201
res_setoptions(res_state statp,const char * options,const char * source)202 static void res_setoptions(res_state statp, const char* options, const char* source) {
203 const char* cp = options;
204 int i;
205 res_state_ext* ext = statp->_u._ext.ext;
206
207 LOG(DEBUG) << "res_setoptions(\"" << options << "\", \"" << source << "\")...";
208
209 while (*cp) {
210 /* skip leading and inner runs of spaces */
211 while (*cp == ' ' || *cp == '\t') cp++;
212 /* search for and process individual options */
213 if (!strncmp(cp, "ndots:", sizeof("ndots:") - 1)) {
214 i = atoi(cp + sizeof("ndots:") - 1);
215 if (i <= RES_MAXNDOTS)
216 statp->ndots = i;
217 else
218 statp->ndots = RES_MAXNDOTS;
219 LOG(DEBUG) << "\tndots=" << statp->ndots;
220
221 } else if (!strncmp(cp, "debug", sizeof("debug") - 1)) {
222 if (!(statp->options & RES_DEBUG)) {
223 LOG(DEBUG) << "res_setoptions(\"" << options << "\", \"" << source << "\")..";
224 statp->options |= RES_DEBUG;
225 }
226 LOG(DEBUG) << "\tdebug";
227
228 } else if (!strncmp(cp, "no_tld_query", sizeof("no_tld_query") - 1) ||
229 !strncmp(cp, "no-tld-query", sizeof("no-tld-query") - 1)) {
230 statp->options |= RES_NOTLDQUERY;
231 } else if (!strncmp(cp, "inet6", sizeof("inet6") - 1)) {
232 statp->options |= RES_USE_INET6;
233 } else if (!strncmp(cp, "rotate", sizeof("rotate") - 1)) {
234 statp->options |= RES_ROTATE;
235 } else if (!strncmp(cp, "no-check-names", sizeof("no-check-names") - 1)) {
236 statp->options |= RES_NOCHECKNAME;
237 }
238 else if (!strncmp(cp, "edns0", sizeof("edns0") - 1)) {
239 statp->options |= RES_USE_EDNS0;
240 }
241 else if (!strncmp(cp, "dname", sizeof("dname") - 1)) {
242 statp->options |= RES_USE_DNAME;
243 } else if (!strncmp(cp, "nibble:", sizeof("nibble:") - 1)) {
244 if (ext == NULL) goto skip;
245 cp += sizeof("nibble:") - 1;
246 i = MIN(strcspn(cp, " \t"), sizeof(ext->nsuffix) - 1);
247 strncpy(ext->nsuffix, cp, (size_t) i);
248 ext->nsuffix[i] = '\0';
249 } else if (!strncmp(cp, "nibble2:", sizeof("nibble2:") - 1)) {
250 if (ext == NULL) goto skip;
251 cp += sizeof("nibble2:") - 1;
252 i = MIN(strcspn(cp, " \t"), sizeof(ext->nsuffix2) - 1);
253 strncpy(ext->nsuffix2, cp, (size_t) i);
254 ext->nsuffix2[i] = '\0';
255 } else if (!strncmp(cp, "v6revmode:", sizeof("v6revmode:") - 1)) {
256 cp += sizeof("v6revmode:") - 1;
257 /* "nibble" and "bitstring" used to be valid */
258 if (!strncmp(cp, "single", sizeof("single") - 1)) {
259 statp->options |= RES_NO_NIBBLE2;
260 } else if (!strncmp(cp, "both", sizeof("both") - 1)) {
261 statp->options &= ~RES_NO_NIBBLE2;
262 }
263 } else {
264 /* XXX - print a warning here? */
265 }
266 skip:
267 /* skip to next run of spaces */
268 while (*cp && *cp != ' ' && *cp != '\t') cp++;
269 }
270 }
271
272 /*
273 * This routine is for closing the socket if a virtual circuit is used and
274 * the program wants to close it. This provides support for endhostent()
275 * which expects to close the socket.
276 *
277 * This routine is not expected to be user visible.
278 */
res_nclose(res_state statp)279 void res_nclose(res_state statp) {
280 int ns;
281
282 if (statp->_vcsock >= 0) {
283 (void) close(statp->_vcsock);
284 statp->_vcsock = -1;
285 statp->_flags &= ~RES_F_VC;
286 }
287 for (ns = 0; ns < statp->_u._ext.nscount; ns++) {
288 if (statp->_u._ext.nssocks[ns] != -1) {
289 (void) close(statp->_u._ext.nssocks[ns]);
290 statp->_u._ext.nssocks[ns] = -1;
291 }
292 }
293 }
294
res_ndestroy(res_state statp)295 void res_ndestroy(res_state statp) {
296 res_nclose(statp);
297 if (statp->_u._ext.ext != NULL) free(statp->_u._ext.ext);
298 statp->options &= ~RES_INIT;
299 statp->_u._ext.ext = NULL;
300 }
301
res_setservers(res_state statp,const sockaddr_union * set,int cnt)302 void res_setservers(res_state statp, const sockaddr_union* set, int cnt) {
303 int i, nserv;
304 size_t size;
305
306 /* close open servers */
307 res_nclose(statp);
308
309 /* cause rtt times to be forgotten */
310 statp->_u._ext.nscount = 0;
311
312 nserv = 0;
313 for (i = 0; i < cnt && nserv < MAXNS; i++) {
314 switch (set->sin.sin_family) {
315 case AF_INET:
316 size = sizeof(set->sin);
317 if (statp->_u._ext.ext)
318 memcpy(&statp->_u._ext.ext->nsaddrs[nserv], &set->sin, size);
319 if (size <= sizeof(statp->nsaddr_list[nserv]))
320 memcpy(&statp->nsaddr_list[nserv], &set->sin, size);
321 else
322 statp->nsaddr_list[nserv].sin_family = 0;
323 nserv++;
324 break;
325
326 #ifdef HAS_INET6_STRUCTS
327 case AF_INET6:
328 size = sizeof(set->sin6);
329 if (statp->_u._ext.ext)
330 memcpy(&statp->_u._ext.ext->nsaddrs[nserv], &set->sin6, size);
331 if (size <= sizeof(statp->nsaddr_list[nserv]))
332 memcpy(&statp->nsaddr_list[nserv], &set->sin6, size);
333 else
334 statp->nsaddr_list[nserv].sin_family = 0;
335 nserv++;
336 break;
337 #endif
338
339 default:
340 break;
341 }
342 set++;
343 }
344 statp->nscount = nserv;
345 }
346
res_getservers(res_state statp,sockaddr_union * set,int cnt)347 int res_getservers(res_state statp, sockaddr_union* set, int cnt) {
348 int i;
349 size_t size;
350 uint16_t family;
351
352 for (i = 0; i < statp->nscount && i < cnt; i++) {
353 if (statp->_u._ext.ext)
354 family = statp->_u._ext.ext->nsaddrs[i].sin.sin_family;
355 else
356 family = statp->nsaddr_list[i].sin_family;
357
358 switch (family) {
359 case AF_INET:
360 size = sizeof(set->sin);
361 if (statp->_u._ext.ext)
362 memcpy(&set->sin, &statp->_u._ext.ext->nsaddrs[i], size);
363 else
364 memcpy(&set->sin, &statp->nsaddr_list[i], size);
365 break;
366
367 #ifdef HAS_INET6_STRUCTS
368 case AF_INET6:
369 size = sizeof(set->sin6);
370 if (statp->_u._ext.ext)
371 memcpy(&set->sin6, &statp->_u._ext.ext->nsaddrs[i], size);
372 else
373 memcpy(&set->sin6, &statp->nsaddr_list[i], size);
374 break;
375 #endif
376
377 default:
378 set->sin.sin_family = 0;
379 break;
380 }
381 set++;
382 }
383 return (statp->nscount);
384 }
385
res_setnetcontext(res_state statp,const struct android_net_context * netcontext)386 void res_setnetcontext(res_state statp, const struct android_net_context* netcontext) {
387 if (statp != NULL) {
388 statp->netid = netcontext->dns_netid;
389 statp->_mark = netcontext->dns_mark;
390 if (netcontext->flags & NET_CONTEXT_FLAG_USE_EDNS) {
391 statp->options |= RES_USE_EDNS0 | RES_USE_DNSSEC;
392 }
393 if (netcontext->flags & NET_CONTEXT_FLAG_USE_LOCAL_NAMESERVERS) {
394 statp->use_local_nameserver = true;
395 }
396 }
397 }
398