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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