1 /* $NetBSD: getaddrinfo.c,v 1.82 2006/03/25 12:09:40 rpaulo Exp $ */
2 /* $KAME: getaddrinfo.c,v 1.29 2000/08/31 17:26:57 itojun Exp $ */
3
4 /*
5 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the project nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 /*
34 * Issues to be discussed:
35 * - Thread safe-ness must be checked.
36 * - Return values. There are nonstandard return values defined and used
37 * in the source code. This is because RFC2553 is silent about which error
38 * code must be returned for which situation.
39 * - IPv4 classful (shortened) form. RFC2553 is silent about it. XNET 5.2
40 * says to use inet_aton() to convert IPv4 numeric to binary (alows
41 * classful form as a result).
42 * current code - disallow classful form for IPv4 (due to use of inet_pton).
43 * - freeaddrinfo(NULL). RFC2553 is silent about it. XNET 5.2 says it is
44 * invalid.
45 * current code - SEGV on freeaddrinfo(NULL)
46 * Note:
47 * - We use getipnodebyname() just for thread-safeness. There's no intent
48 * to let it do PF_UNSPEC (actually we never pass PF_UNSPEC to
49 * getipnodebyname().
50 * - The code filters out AFs that are not supported by the kernel,
51 * when globbing NULL hostname (to loopback, or wildcard). Is it the right
52 * thing to do? What is the relationship with post-RFC2553 AI_ADDRCONFIG
53 * in ai_flags?
54 * - (post-2553) semantics of AI_ADDRCONFIG itself is too vague.
55 * (1) what should we do against numeric hostname (2) what should we do
56 * against NULL hostname (3) what is AI_ADDRCONFIG itself. AF not ready?
57 * non-loopback address configured? global address configured?
58 * - To avoid search order issue, we have a big amount of code duplicate
59 * from gethnamaddr.c and some other places. The issues that there's no
60 * lower layer function to lookup "IPv4 or IPv6" record. Calling
61 * gethostbyname2 from getaddrinfo will end up in wrong search order, as
62 * follows:
63 * - The code makes use of following calls when asked to resolver with
64 * ai_family = PF_UNSPEC:
65 * getipnodebyname(host, AF_INET6);
66 * getipnodebyname(host, AF_INET);
67 * This will result in the following queries if the node is configure to
68 * prefer /etc/hosts than DNS:
69 * lookup /etc/hosts for IPv6 address
70 * lookup DNS for IPv6 address
71 * lookup /etc/hosts for IPv4 address
72 * lookup DNS for IPv4 address
73 * which may not meet people's requirement.
74 * The right thing to happen is to have underlying layer which does
75 * PF_UNSPEC lookup (lookup both) and return chain of addrinfos.
76 * This would result in a bit of code duplicate with _dns_ghbyname() and
77 * friends.
78 */
79
80 #include <fcntl.h>
81 #include <sys/cdefs.h>
82 #include <sys/types.h>
83 #include <sys/stat.h>
84 #include <sys/param.h>
85 #include <sys/socket.h>
86 #include <sys/un.h>
87 #include <net/if.h>
88 #include <netinet/in.h>
89 #include <arpa/inet.h>
90 #include "arpa_nameser.h"
91 #include <assert.h>
92 #include <ctype.h>
93 #include <errno.h>
94 #include <netdb.h>
95 #include "resolv_private.h"
96 #include <stddef.h>
97 #include <stdio.h>
98 #include <stdlib.h>
99 #include <string.h>
100 #include <strings.h>
101 #include <unistd.h>
102
103 #include <syslog.h>
104 #include <stdarg.h>
105 #include "nsswitch.h"
106
107 #ifdef ANDROID_CHANGES
108 #include <sys/system_properties.h>
109 #endif /* ANDROID_CHANGES */
110
111 typedef union sockaddr_union {
112 struct sockaddr generic;
113 struct sockaddr_in in;
114 struct sockaddr_in6 in6;
115 } sockaddr_union;
116
117 #define SUCCESS 0
118 #define ANY 0
119 #define YES 1
120 #define NO 0
121
122 static const char in_addrany[] = { 0, 0, 0, 0 };
123 static const char in_loopback[] = { 127, 0, 0, 1 };
124 #ifdef INET6
125 static const char in6_addrany[] = {
126 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
127 };
128 static const char in6_loopback[] = {
129 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
130 };
131 #endif
132
133 // This should be synchronized to ResponseCode.h
134 static const int DnsProxyQueryResult = 222;
135
136 static const struct afd {
137 int a_af;
138 int a_addrlen;
139 int a_socklen;
140 int a_off;
141 const char *a_addrany;
142 const char *a_loopback;
143 int a_scoped;
144 } afdl [] = {
145 #ifdef INET6
146 {PF_INET6, sizeof(struct in6_addr),
147 sizeof(struct sockaddr_in6),
148 offsetof(struct sockaddr_in6, sin6_addr),
149 in6_addrany, in6_loopback, 1},
150 #endif
151 {PF_INET, sizeof(struct in_addr),
152 sizeof(struct sockaddr_in),
153 offsetof(struct sockaddr_in, sin_addr),
154 in_addrany, in_loopback, 0},
155 {0, 0, 0, 0, NULL, NULL, 0},
156 };
157
158 struct explore {
159 int e_af;
160 int e_socktype;
161 int e_protocol;
162 const char *e_protostr;
163 int e_wild;
164 #define WILD_AF(ex) ((ex)->e_wild & 0x01)
165 #define WILD_SOCKTYPE(ex) ((ex)->e_wild & 0x02)
166 #define WILD_PROTOCOL(ex) ((ex)->e_wild & 0x04)
167 };
168
169 static const struct explore explore[] = {
170 #if 0
171 { PF_LOCAL, 0, ANY, ANY, NULL, 0x01 },
172 #endif
173 #ifdef INET6
174 { PF_INET6, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
175 { PF_INET6, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
176 { PF_INET6, SOCK_RAW, ANY, NULL, 0x05 },
177 #endif
178 { PF_INET, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
179 { PF_INET, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
180 { PF_INET, SOCK_RAW, ANY, NULL, 0x05 },
181 { PF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
182 { PF_UNSPEC, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
183 { PF_UNSPEC, SOCK_RAW, ANY, NULL, 0x05 },
184 { -1, 0, 0, NULL, 0 },
185 };
186
187 #ifdef INET6
188 #define PTON_MAX 16
189 #else
190 #define PTON_MAX 4
191 #endif
192
193 static const ns_src default_dns_files[] = {
194 { NSSRC_FILES, NS_SUCCESS },
195 { NSSRC_DNS, NS_SUCCESS },
196 { 0, 0 }
197 };
198
199 #define MAXPACKET (64*1024)
200
201 typedef union {
202 HEADER hdr;
203 u_char buf[MAXPACKET];
204 } querybuf;
205
206 struct res_target {
207 struct res_target *next;
208 const char *name; /* domain name */
209 int qclass, qtype; /* class and type of query */
210 u_char *answer; /* buffer to put answer */
211 int anslen; /* size of answer buffer */
212 int n; /* result length */
213 };
214
215 static int str2number(const char *);
216 static int explore_fqdn(const struct addrinfo *, const char *,
217 const char *, struct addrinfo **, const char *iface);
218 static int explore_null(const struct addrinfo *,
219 const char *, struct addrinfo **);
220 static int explore_numeric(const struct addrinfo *, const char *,
221 const char *, struct addrinfo **, const char *);
222 static int explore_numeric_scope(const struct addrinfo *, const char *,
223 const char *, struct addrinfo **);
224 static int get_canonname(const struct addrinfo *,
225 struct addrinfo *, const char *);
226 static struct addrinfo *get_ai(const struct addrinfo *,
227 const struct afd *, const char *);
228 static int get_portmatch(const struct addrinfo *, const char *);
229 static int get_port(const struct addrinfo *, const char *, int);
230 static const struct afd *find_afd(int);
231 #ifdef INET6
232 static int ip6_str2scopeid(char *, struct sockaddr_in6 *, u_int32_t *);
233 #endif
234
235 static struct addrinfo *getanswer(const querybuf *, int, const char *, int,
236 const struct addrinfo *);
237 static int _dns_getaddrinfo(void *, void *, va_list);
238 static void _sethtent(FILE **);
239 static void _endhtent(FILE **);
240 static struct addrinfo *_gethtent(FILE **, const char *,
241 const struct addrinfo *);
242 static int _files_getaddrinfo(void *, void *, va_list);
243
244 static int res_queryN(const char *, struct res_target *, res_state);
245 static int res_searchN(const char *, struct res_target *, res_state);
246 static int res_querydomainN(const char *, const char *,
247 struct res_target *, res_state);
248
249 static const char * const ai_errlist[] = {
250 "Success",
251 "Address family for hostname not supported", /* EAI_ADDRFAMILY */
252 "Temporary failure in name resolution", /* EAI_AGAIN */
253 "Invalid value for ai_flags", /* EAI_BADFLAGS */
254 "Non-recoverable failure in name resolution", /* EAI_FAIL */
255 "ai_family not supported", /* EAI_FAMILY */
256 "Memory allocation failure", /* EAI_MEMORY */
257 "No address associated with hostname", /* EAI_NODATA */
258 "hostname nor servname provided, or not known", /* EAI_NONAME */
259 "servname not supported for ai_socktype", /* EAI_SERVICE */
260 "ai_socktype not supported", /* EAI_SOCKTYPE */
261 "System error returned in errno", /* EAI_SYSTEM */
262 "Invalid value for hints", /* EAI_BADHINTS */
263 "Resolved protocol is unknown", /* EAI_PROTOCOL */
264 "Argument buffer overflow", /* EAI_OVERFLOW */
265 "Unknown error", /* EAI_MAX */
266 };
267
268 /* XXX macros that make external reference is BAD. */
269
270 #define GET_AI(ai, afd, addr) \
271 do { \
272 /* external reference: pai, error, and label free */ \
273 (ai) = get_ai(pai, (afd), (addr)); \
274 if ((ai) == NULL) { \
275 error = EAI_MEMORY; \
276 goto free; \
277 } \
278 } while (/*CONSTCOND*/0)
279
280 #define GET_PORT(ai, serv) \
281 do { \
282 /* external reference: error and label free */ \
283 error = get_port((ai), (serv), 0); \
284 if (error != 0) \
285 goto free; \
286 } while (/*CONSTCOND*/0)
287
288 #define GET_CANONNAME(ai, str) \
289 do { \
290 /* external reference: pai, error and label free */ \
291 error = get_canonname(pai, (ai), (str)); \
292 if (error != 0) \
293 goto free; \
294 } while (/*CONSTCOND*/0)
295
296 #define ERR(err) \
297 do { \
298 /* external reference: error, and label bad */ \
299 error = (err); \
300 goto bad; \
301 /*NOTREACHED*/ \
302 } while (/*CONSTCOND*/0)
303
304 #define MATCH_FAMILY(x, y, w) \
305 ((x) == (y) || (/*CONSTCOND*/(w) && ((x) == PF_UNSPEC || \
306 (y) == PF_UNSPEC)))
307 #define MATCH(x, y, w) \
308 ((x) == (y) || (/*CONSTCOND*/(w) && ((x) == ANY || (y) == ANY)))
309
310 const char *
gai_strerror(int ecode)311 gai_strerror(int ecode)
312 {
313 if (ecode < 0 || ecode > EAI_MAX)
314 ecode = EAI_MAX;
315 return ai_errlist[ecode];
316 }
317
318 void
freeaddrinfo(struct addrinfo * ai)319 freeaddrinfo(struct addrinfo *ai)
320 {
321 struct addrinfo *next;
322
323 assert(ai != NULL);
324
325 do {
326 next = ai->ai_next;
327 if (ai->ai_canonname)
328 free(ai->ai_canonname);
329 /* no need to free(ai->ai_addr) */
330 free(ai);
331 ai = next;
332 } while (ai);
333 }
334
335 static int
str2number(const char * p)336 str2number(const char *p)
337 {
338 char *ep;
339 unsigned long v;
340
341 assert(p != NULL);
342
343 if (*p == '\0')
344 return -1;
345 ep = NULL;
346 errno = 0;
347 v = strtoul(p, &ep, 10);
348 if (errno == 0 && ep && *ep == '\0' && v <= UINT_MAX)
349 return v;
350 else
351 return -1;
352 }
353
354 /*
355 * Connect a UDP socket to a given unicast address. This will cause no network
356 * traffic, but will fail fast if the system has no or limited reachability to
357 * the destination (e.g., no IPv4 address, no IPv6 default route, ...).
358 */
359 static int
_test_connect(int pf,struct sockaddr * addr,size_t addrlen)360 _test_connect(int pf, struct sockaddr *addr, size_t addrlen) {
361 int s = socket(pf, SOCK_DGRAM, IPPROTO_UDP);
362 if (s < 0)
363 return 0;
364 int ret;
365 do {
366 ret = connect(s, addr, addrlen);
367 } while (ret < 0 && errno == EINTR);
368 int success = (ret == 0);
369 do {
370 ret = close(s);
371 } while (ret < 0 && errno == EINTR);
372 return success;
373 }
374
375 /*
376 * The following functions determine whether IPv4 or IPv6 connectivity is
377 * available in order to implement AI_ADDRCONFIG.
378 *
379 * Strictly speaking, AI_ADDRCONFIG should not look at whether connectivity is
380 * available, but whether addresses of the specified family are "configured
381 * on the local system". However, bionic doesn't currently support getifaddrs,
382 * so checking for connectivity is the next best thing.
383 */
384 static int
_have_ipv6()385 _have_ipv6() {
386 static const struct sockaddr_in6 sin6_test = {
387 .sin6_family = AF_INET6,
388 .sin6_addr.s6_addr = { // 2000::
389 0x20, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
390 };
391 sockaddr_union addr = { .in6 = sin6_test };
392 return _test_connect(PF_INET6, &addr.generic, sizeof(addr.in6));
393 }
394
395 static int
_have_ipv4()396 _have_ipv4() {
397 static const struct sockaddr_in sin_test = {
398 .sin_family = AF_INET,
399 .sin_addr.s_addr = __constant_htonl(0x08080808L) // 8.8.8.8
400 };
401 sockaddr_union addr = { .in = sin_test };
402 return _test_connect(PF_INET, &addr.generic, sizeof(addr.in));
403 }
404
405 // Returns 0 on success, else returns on error.
406 static int
android_getaddrinfo_proxy(const char * hostname,const char * servname,const struct addrinfo * hints,struct addrinfo ** res,const char * iface)407 android_getaddrinfo_proxy(
408 const char *hostname, const char *servname,
409 const struct addrinfo *hints, struct addrinfo **res, const char *iface)
410 {
411 int sock;
412 const int one = 1;
413 struct sockaddr_un proxy_addr;
414 FILE* proxy = NULL;
415 int success = 0;
416
417 // Clear this at start, as we use its non-NULLness later (in the
418 // error path) to decide if we have to free up any memory we
419 // allocated in the process (before failing).
420 *res = NULL;
421
422 // Bogus things we can't serialize. Don't use the proxy. These will fail - let them.
423 if ((hostname != NULL &&
424 strcspn(hostname, " \n\r\t^'\"") != strlen(hostname)) ||
425 (servname != NULL &&
426 strcspn(servname, " \n\r\t^'\"") != strlen(servname))) {
427 return EAI_NODATA;
428 }
429
430 sock = socket(AF_UNIX, SOCK_STREAM, 0);
431 if (sock < 0) {
432 return EAI_NODATA;
433 }
434
435 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
436 memset(&proxy_addr, 0, sizeof(proxy_addr));
437 proxy_addr.sun_family = AF_UNIX;
438 strlcpy(proxy_addr.sun_path, "/dev/socket/dnsproxyd",
439 sizeof(proxy_addr.sun_path));
440 if (TEMP_FAILURE_RETRY(connect(sock,
441 (const struct sockaddr*) &proxy_addr,
442 sizeof(proxy_addr))) != 0) {
443 close(sock);
444 return EAI_NODATA;
445 }
446
447 // Send the request.
448 proxy = fdopen(sock, "r+");
449 if (fprintf(proxy, "getaddrinfo %s %s %d %d %d %d %s",
450 hostname == NULL ? "^" : hostname,
451 servname == NULL ? "^" : servname,
452 hints == NULL ? -1 : hints->ai_flags,
453 hints == NULL ? -1 : hints->ai_family,
454 hints == NULL ? -1 : hints->ai_socktype,
455 hints == NULL ? -1 : hints->ai_protocol,
456 iface == NULL ? "^" : iface) < 0) {
457 goto exit;
458 }
459 // literal NULL byte at end, required by FrameworkListener
460 if (fputc(0, proxy) == EOF ||
461 fflush(proxy) != 0) {
462 goto exit;
463 }
464
465 char buf[4];
466 // read result code for gethostbyaddr
467 if (fread(buf, 1, sizeof(buf), proxy) != sizeof(buf)) {
468 goto exit;
469 }
470
471 int result_code = (int)strtol(buf, NULL, 10);
472 // verify the code itself
473 if (result_code != DnsProxyQueryResult ) {
474 fread(buf, 1, sizeof(buf), proxy);
475 goto exit;
476 }
477
478 struct addrinfo* ai = NULL;
479 struct addrinfo** nextres = res;
480 while (1) {
481 uint32_t addrinfo_len;
482 if (fread(&addrinfo_len, sizeof(addrinfo_len),
483 1, proxy) != 1) {
484 break;
485 }
486 addrinfo_len = ntohl(addrinfo_len);
487 if (addrinfo_len == 0) {
488 success = 1;
489 break;
490 }
491
492 if (addrinfo_len < sizeof(struct addrinfo)) {
493 break;
494 }
495 struct addrinfo* ai = calloc(1, addrinfo_len +
496 sizeof(struct sockaddr_storage));
497 if (ai == NULL) {
498 break;
499 }
500
501 if (fread(ai, addrinfo_len, 1, proxy) != 1) {
502 // Error; fall through.
503 break;
504 }
505
506 // Zero out the pointer fields we copied which aren't
507 // valid in this address space.
508 ai->ai_addr = NULL;
509 ai->ai_canonname = NULL;
510 ai->ai_next = NULL;
511
512 // struct sockaddr
513 uint32_t addr_len;
514 if (fread(&addr_len, sizeof(addr_len), 1, proxy) != 1) {
515 break;
516 }
517 addr_len = ntohl(addr_len);
518 if (addr_len != 0) {
519 if (addr_len > sizeof(struct sockaddr_storage)) {
520 // Bogus; too big.
521 break;
522 }
523 struct sockaddr* addr = (struct sockaddr*)(ai + 1);
524 if (fread(addr, addr_len, 1, proxy) != 1) {
525 break;
526 }
527 ai->ai_addr = addr;
528 }
529
530 // cannonname
531 uint32_t name_len;
532 if (fread(&name_len, sizeof(name_len), 1, proxy) != 1) {
533 break;
534 }
535 name_len = ntohl(name_len);
536 if (name_len != 0) {
537 ai->ai_canonname = (char*) malloc(name_len);
538 if (fread(ai->ai_canonname, name_len, 1, proxy) != 1) {
539 break;
540 }
541 if (ai->ai_canonname[name_len - 1] != '\0') {
542 // The proxy should be returning this
543 // NULL-terminated.
544 break;
545 }
546 }
547
548 *nextres = ai;
549 nextres = &ai->ai_next;
550 ai = NULL;
551 }
552
553 if (ai != NULL) {
554 // Clean up partially-built addrinfo that we never ended up
555 // attaching to the response.
556 freeaddrinfo(ai);
557 }
558 exit:
559 if (proxy != NULL) {
560 fclose(proxy);
561 }
562
563 if (success) {
564 return 0;
565 }
566
567 // Proxy failed;
568 // clean up memory we might've allocated.
569 if (*res) {
570 freeaddrinfo(*res);
571 *res = NULL;
572 }
573 return EAI_NODATA;
574 }
575
576 int
getaddrinfo(const char * hostname,const char * servname,const struct addrinfo * hints,struct addrinfo ** res)577 getaddrinfo(const char *hostname, const char *servname,
578 const struct addrinfo *hints, struct addrinfo **res)
579 {
580 return android_getaddrinfoforiface(hostname, servname, hints, NULL, res);
581 }
582
583 int
android_getaddrinfoforiface(const char * hostname,const char * servname,const struct addrinfo * hints,const char * iface,struct addrinfo ** res)584 android_getaddrinfoforiface(const char *hostname, const char *servname,
585 const struct addrinfo *hints, const char *iface, struct addrinfo **res)
586 {
587 struct addrinfo sentinel;
588 struct addrinfo *cur;
589 int error = 0;
590 struct addrinfo ai;
591 struct addrinfo ai0;
592 struct addrinfo *pai;
593 const struct explore *ex;
594 const char* cache_mode = getenv("ANDROID_DNS_MODE");
595
596 /* hostname is allowed to be NULL */
597 /* servname is allowed to be NULL */
598 /* hints is allowed to be NULL */
599 assert(res != NULL);
600 memset(&sentinel, 0, sizeof(sentinel));
601 cur = &sentinel;
602 pai = &ai;
603 pai->ai_flags = 0;
604 pai->ai_family = PF_UNSPEC;
605 pai->ai_socktype = ANY;
606 pai->ai_protocol = ANY;
607 pai->ai_addrlen = 0;
608 pai->ai_canonname = NULL;
609 pai->ai_addr = NULL;
610 pai->ai_next = NULL;
611
612 if (hostname == NULL && servname == NULL)
613 return EAI_NONAME;
614 if (hints) {
615 /* error check for hints */
616 if (hints->ai_addrlen || hints->ai_canonname ||
617 hints->ai_addr || hints->ai_next)
618 ERR(EAI_BADHINTS); /* xxx */
619 if (hints->ai_flags & ~AI_MASK)
620 ERR(EAI_BADFLAGS);
621 switch (hints->ai_family) {
622 case PF_UNSPEC:
623 case PF_INET:
624 #ifdef INET6
625 case PF_INET6:
626 #endif
627 break;
628 default:
629 ERR(EAI_FAMILY);
630 }
631 memcpy(pai, hints, sizeof(*pai));
632
633 /*
634 * if both socktype/protocol are specified, check if they
635 * are meaningful combination.
636 */
637 if (pai->ai_socktype != ANY && pai->ai_protocol != ANY) {
638 for (ex = explore; ex->e_af >= 0; ex++) {
639 if (pai->ai_family != ex->e_af)
640 continue;
641 if (ex->e_socktype == ANY)
642 continue;
643 if (ex->e_protocol == ANY)
644 continue;
645 if (pai->ai_socktype == ex->e_socktype
646 && pai->ai_protocol != ex->e_protocol) {
647 ERR(EAI_BADHINTS);
648 }
649 }
650 }
651 }
652
653 /*
654 * check for special cases. (1) numeric servname is disallowed if
655 * socktype/protocol are left unspecified. (2) servname is disallowed
656 * for raw and other inet{,6} sockets.
657 */
658 if (MATCH_FAMILY(pai->ai_family, PF_INET, 1)
659 #ifdef PF_INET6
660 || MATCH_FAMILY(pai->ai_family, PF_INET6, 1)
661 #endif
662 ) {
663 ai0 = *pai; /* backup *pai */
664
665 if (pai->ai_family == PF_UNSPEC) {
666 #ifdef PF_INET6
667 pai->ai_family = PF_INET6;
668 #else
669 pai->ai_family = PF_INET;
670 #endif
671 }
672 error = get_portmatch(pai, servname);
673 if (error)
674 ERR(error);
675
676 *pai = ai0;
677 }
678
679 ai0 = *pai;
680
681 /* NULL hostname, or numeric hostname */
682 for (ex = explore; ex->e_af >= 0; ex++) {
683 *pai = ai0;
684
685 /* PF_UNSPEC entries are prepared for DNS queries only */
686 if (ex->e_af == PF_UNSPEC)
687 continue;
688
689 if (!MATCH_FAMILY(pai->ai_family, ex->e_af, WILD_AF(ex)))
690 continue;
691 if (!MATCH(pai->ai_socktype, ex->e_socktype, WILD_SOCKTYPE(ex)))
692 continue;
693 if (!MATCH(pai->ai_protocol, ex->e_protocol, WILD_PROTOCOL(ex)))
694 continue;
695
696 if (pai->ai_family == PF_UNSPEC)
697 pai->ai_family = ex->e_af;
698 if (pai->ai_socktype == ANY && ex->e_socktype != ANY)
699 pai->ai_socktype = ex->e_socktype;
700 if (pai->ai_protocol == ANY && ex->e_protocol != ANY)
701 pai->ai_protocol = ex->e_protocol;
702
703 if (hostname == NULL)
704 error = explore_null(pai, servname, &cur->ai_next);
705 else
706 error = explore_numeric_scope(pai, hostname, servname,
707 &cur->ai_next);
708
709 if (error)
710 goto free;
711
712 while (cur->ai_next)
713 cur = cur->ai_next;
714 }
715
716 /*
717 * XXX
718 * If numeric representation of AF1 can be interpreted as FQDN
719 * representation of AF2, we need to think again about the code below.
720 */
721 if (sentinel.ai_next)
722 goto good;
723
724 if (hostname == NULL)
725 ERR(EAI_NODATA);
726 if (pai->ai_flags & AI_NUMERICHOST)
727 ERR(EAI_NONAME);
728
729 /*
730 * BEGIN ANDROID CHANGES; proxying to the cache
731 */
732 if (cache_mode == NULL || strcmp(cache_mode, "local") != 0) {
733 // we're not the proxy - pass the request to them
734 return android_getaddrinfo_proxy(hostname, servname, hints, res, iface);
735 }
736
737 /*
738 * hostname as alphabetical name.
739 * we would like to prefer AF_INET6 than AF_INET, so we'll make a
740 * outer loop by AFs.
741 */
742 for (ex = explore; ex->e_af >= 0; ex++) {
743 *pai = ai0;
744
745 /* require exact match for family field */
746 if (pai->ai_family != ex->e_af)
747 continue;
748
749 if (!MATCH(pai->ai_socktype, ex->e_socktype,
750 WILD_SOCKTYPE(ex))) {
751 continue;
752 }
753 if (!MATCH(pai->ai_protocol, ex->e_protocol,
754 WILD_PROTOCOL(ex))) {
755 continue;
756 }
757
758 if (pai->ai_socktype == ANY && ex->e_socktype != ANY)
759 pai->ai_socktype = ex->e_socktype;
760 if (pai->ai_protocol == ANY && ex->e_protocol != ANY)
761 pai->ai_protocol = ex->e_protocol;
762
763 error = explore_fqdn(pai, hostname, servname,
764 &cur->ai_next, iface);
765
766 while (cur && cur->ai_next)
767 cur = cur->ai_next;
768 }
769
770 /* XXX */
771 if (sentinel.ai_next)
772 error = 0;
773
774 if (error)
775 goto free;
776 if (error == 0) {
777 if (sentinel.ai_next) {
778 good:
779 *res = sentinel.ai_next;
780 return SUCCESS;
781 } else
782 error = EAI_FAIL;
783 }
784 free:
785 bad:
786 if (sentinel.ai_next)
787 freeaddrinfo(sentinel.ai_next);
788 *res = NULL;
789 return error;
790 }
791
792 /*
793 * FQDN hostname, DNS lookup
794 */
795 static int
explore_fqdn(const struct addrinfo * pai,const char * hostname,const char * servname,struct addrinfo ** res,const char * iface)796 explore_fqdn(const struct addrinfo *pai, const char *hostname,
797 const char *servname, struct addrinfo **res, const char *iface)
798 {
799 struct addrinfo *result;
800 struct addrinfo *cur;
801 int error = 0;
802 static const ns_dtab dtab[] = {
803 NS_FILES_CB(_files_getaddrinfo, NULL)
804 { NSSRC_DNS, _dns_getaddrinfo, NULL }, /* force -DHESIOD */
805 NS_NIS_CB(_yp_getaddrinfo, NULL)
806 { 0, 0, 0 }
807 };
808
809 assert(pai != NULL);
810 /* hostname may be NULL */
811 /* servname may be NULL */
812 assert(res != NULL);
813
814 result = NULL;
815
816 /*
817 * if the servname does not match socktype/protocol, ignore it.
818 */
819 if (get_portmatch(pai, servname) != 0)
820 return 0;
821
822 switch (nsdispatch(&result, dtab, NSDB_HOSTS, "getaddrinfo",
823 default_dns_files, hostname, pai, iface)) {
824 case NS_TRYAGAIN:
825 error = EAI_AGAIN;
826 goto free;
827 case NS_UNAVAIL:
828 error = EAI_FAIL;
829 goto free;
830 case NS_NOTFOUND:
831 error = EAI_NODATA;
832 goto free;
833 case NS_SUCCESS:
834 error = 0;
835 for (cur = result; cur; cur = cur->ai_next) {
836 GET_PORT(cur, servname);
837 /* canonname should be filled already */
838 }
839 break;
840 }
841
842 *res = result;
843
844 return 0;
845
846 free:
847 if (result)
848 freeaddrinfo(result);
849 return error;
850 }
851
852 /*
853 * hostname == NULL.
854 * passive socket -> anyaddr (0.0.0.0 or ::)
855 * non-passive socket -> localhost (127.0.0.1 or ::1)
856 */
857 static int
explore_null(const struct addrinfo * pai,const char * servname,struct addrinfo ** res)858 explore_null(const struct addrinfo *pai, const char *servname,
859 struct addrinfo **res)
860 {
861 int s;
862 const struct afd *afd;
863 struct addrinfo *cur;
864 struct addrinfo sentinel;
865 int error;
866
867 assert(pai != NULL);
868 /* servname may be NULL */
869 assert(res != NULL);
870
871 *res = NULL;
872 sentinel.ai_next = NULL;
873 cur = &sentinel;
874
875 /*
876 * filter out AFs that are not supported by the kernel
877 * XXX errno?
878 */
879 s = socket(pai->ai_family, SOCK_DGRAM, 0);
880 if (s < 0) {
881 if (errno != EMFILE)
882 return 0;
883 } else
884 close(s);
885
886 /*
887 * if the servname does not match socktype/protocol, ignore it.
888 */
889 if (get_portmatch(pai, servname) != 0)
890 return 0;
891
892 afd = find_afd(pai->ai_family);
893 if (afd == NULL)
894 return 0;
895
896 if (pai->ai_flags & AI_PASSIVE) {
897 GET_AI(cur->ai_next, afd, afd->a_addrany);
898 /* xxx meaningless?
899 * GET_CANONNAME(cur->ai_next, "anyaddr");
900 */
901 GET_PORT(cur->ai_next, servname);
902 } else {
903 GET_AI(cur->ai_next, afd, afd->a_loopback);
904 /* xxx meaningless?
905 * GET_CANONNAME(cur->ai_next, "localhost");
906 */
907 GET_PORT(cur->ai_next, servname);
908 }
909 cur = cur->ai_next;
910
911 *res = sentinel.ai_next;
912 return 0;
913
914 free:
915 if (sentinel.ai_next)
916 freeaddrinfo(sentinel.ai_next);
917 return error;
918 }
919
920 /*
921 * numeric hostname
922 */
923 static int
explore_numeric(const struct addrinfo * pai,const char * hostname,const char * servname,struct addrinfo ** res,const char * canonname)924 explore_numeric(const struct addrinfo *pai, const char *hostname,
925 const char *servname, struct addrinfo **res, const char *canonname)
926 {
927 const struct afd *afd;
928 struct addrinfo *cur;
929 struct addrinfo sentinel;
930 int error;
931 char pton[PTON_MAX];
932
933 assert(pai != NULL);
934 /* hostname may be NULL */
935 /* servname may be NULL */
936 assert(res != NULL);
937
938 *res = NULL;
939 sentinel.ai_next = NULL;
940 cur = &sentinel;
941
942 /*
943 * if the servname does not match socktype/protocol, ignore it.
944 */
945 if (get_portmatch(pai, servname) != 0)
946 return 0;
947
948 afd = find_afd(pai->ai_family);
949 if (afd == NULL)
950 return 0;
951
952 switch (afd->a_af) {
953 #if 0 /*X/Open spec*/
954 case AF_INET:
955 if (inet_aton(hostname, (struct in_addr *)pton) == 1) {
956 if (pai->ai_family == afd->a_af ||
957 pai->ai_family == PF_UNSPEC /*?*/) {
958 GET_AI(cur->ai_next, afd, pton);
959 GET_PORT(cur->ai_next, servname);
960 if ((pai->ai_flags & AI_CANONNAME)) {
961 /*
962 * Set the numeric address itself as
963 * the canonical name, based on a
964 * clarification in rfc2553bis-03.
965 */
966 GET_CANONNAME(cur->ai_next, canonname);
967 }
968 while (cur && cur->ai_next)
969 cur = cur->ai_next;
970 } else
971 ERR(EAI_FAMILY); /*xxx*/
972 }
973 break;
974 #endif
975 default:
976 if (inet_pton(afd->a_af, hostname, pton) == 1) {
977 if (pai->ai_family == afd->a_af ||
978 pai->ai_family == PF_UNSPEC /*?*/) {
979 GET_AI(cur->ai_next, afd, pton);
980 GET_PORT(cur->ai_next, servname);
981 if ((pai->ai_flags & AI_CANONNAME)) {
982 /*
983 * Set the numeric address itself as
984 * the canonical name, based on a
985 * clarification in rfc2553bis-03.
986 */
987 GET_CANONNAME(cur->ai_next, canonname);
988 }
989 while (cur->ai_next)
990 cur = cur->ai_next;
991 } else
992 ERR(EAI_FAMILY); /*xxx*/
993 }
994 break;
995 }
996
997 *res = sentinel.ai_next;
998 return 0;
999
1000 free:
1001 bad:
1002 if (sentinel.ai_next)
1003 freeaddrinfo(sentinel.ai_next);
1004 return error;
1005 }
1006
1007 /*
1008 * numeric hostname with scope
1009 */
1010 static int
explore_numeric_scope(const struct addrinfo * pai,const char * hostname,const char * servname,struct addrinfo ** res)1011 explore_numeric_scope(const struct addrinfo *pai, const char *hostname,
1012 const char *servname, struct addrinfo **res)
1013 {
1014 #if !defined(SCOPE_DELIMITER) || !defined(INET6)
1015 return explore_numeric(pai, hostname, servname, res, hostname);
1016 #else
1017 const struct afd *afd;
1018 struct addrinfo *cur;
1019 int error;
1020 char *cp, *hostname2 = NULL, *scope, *addr;
1021 struct sockaddr_in6 *sin6;
1022
1023 assert(pai != NULL);
1024 /* hostname may be NULL */
1025 /* servname may be NULL */
1026 assert(res != NULL);
1027
1028 /*
1029 * if the servname does not match socktype/protocol, ignore it.
1030 */
1031 if (get_portmatch(pai, servname) != 0)
1032 return 0;
1033
1034 afd = find_afd(pai->ai_family);
1035 if (afd == NULL)
1036 return 0;
1037
1038 if (!afd->a_scoped)
1039 return explore_numeric(pai, hostname, servname, res, hostname);
1040
1041 cp = strchr(hostname, SCOPE_DELIMITER);
1042 if (cp == NULL)
1043 return explore_numeric(pai, hostname, servname, res, hostname);
1044
1045 /*
1046 * Handle special case of <scoped_address><delimiter><scope id>
1047 */
1048 hostname2 = strdup(hostname);
1049 if (hostname2 == NULL)
1050 return EAI_MEMORY;
1051 /* terminate at the delimiter */
1052 hostname2[cp - hostname] = '\0';
1053 addr = hostname2;
1054 scope = cp + 1;
1055
1056 error = explore_numeric(pai, addr, servname, res, hostname);
1057 if (error == 0) {
1058 u_int32_t scopeid;
1059
1060 for (cur = *res; cur; cur = cur->ai_next) {
1061 if (cur->ai_family != AF_INET6)
1062 continue;
1063 sin6 = (struct sockaddr_in6 *)(void *)cur->ai_addr;
1064 if (ip6_str2scopeid(scope, sin6, &scopeid) == -1) {
1065 free(hostname2);
1066 return(EAI_NODATA); /* XXX: is return OK? */
1067 }
1068 sin6->sin6_scope_id = scopeid;
1069 }
1070 }
1071
1072 free(hostname2);
1073
1074 return error;
1075 #endif
1076 }
1077
1078 static int
get_canonname(const struct addrinfo * pai,struct addrinfo * ai,const char * str)1079 get_canonname(const struct addrinfo *pai, struct addrinfo *ai, const char *str)
1080 {
1081
1082 assert(pai != NULL);
1083 assert(ai != NULL);
1084 assert(str != NULL);
1085
1086 if ((pai->ai_flags & AI_CANONNAME) != 0) {
1087 ai->ai_canonname = strdup(str);
1088 if (ai->ai_canonname == NULL)
1089 return EAI_MEMORY;
1090 }
1091 return 0;
1092 }
1093
1094 static struct addrinfo *
get_ai(const struct addrinfo * pai,const struct afd * afd,const char * addr)1095 get_ai(const struct addrinfo *pai, const struct afd *afd, const char *addr)
1096 {
1097 char *p;
1098 struct addrinfo *ai;
1099
1100 assert(pai != NULL);
1101 assert(afd != NULL);
1102 assert(addr != NULL);
1103
1104 ai = (struct addrinfo *)malloc(sizeof(struct addrinfo)
1105 + (afd->a_socklen));
1106 if (ai == NULL)
1107 return NULL;
1108
1109 memcpy(ai, pai, sizeof(struct addrinfo));
1110 ai->ai_addr = (struct sockaddr *)(void *)(ai + 1);
1111 memset(ai->ai_addr, 0, (size_t)afd->a_socklen);
1112
1113 #ifdef HAVE_SA_LEN
1114 ai->ai_addr->sa_len = afd->a_socklen;
1115 #endif
1116
1117 ai->ai_addrlen = afd->a_socklen;
1118 #if defined (__alpha__) || (defined(__i386__) && defined(_LP64)) || defined(__sparc64__)
1119 ai->__ai_pad0 = 0;
1120 #endif
1121 ai->ai_addr->sa_family = ai->ai_family = afd->a_af;
1122 p = (char *)(void *)(ai->ai_addr);
1123 memcpy(p + afd->a_off, addr, (size_t)afd->a_addrlen);
1124 return ai;
1125 }
1126
1127 static int
get_portmatch(const struct addrinfo * ai,const char * servname)1128 get_portmatch(const struct addrinfo *ai, const char *servname)
1129 {
1130
1131 assert(ai != NULL);
1132 /* servname may be NULL */
1133
1134 return get_port(ai, servname, 1);
1135 }
1136
1137 static int
get_port(const struct addrinfo * ai,const char * servname,int matchonly)1138 get_port(const struct addrinfo *ai, const char *servname, int matchonly)
1139 {
1140 const char *proto;
1141 struct servent *sp;
1142 int port;
1143 int allownumeric;
1144
1145 assert(ai != NULL);
1146 /* servname may be NULL */
1147
1148 if (servname == NULL)
1149 return 0;
1150 switch (ai->ai_family) {
1151 case AF_INET:
1152 #ifdef AF_INET6
1153 case AF_INET6:
1154 #endif
1155 break;
1156 default:
1157 return 0;
1158 }
1159
1160 switch (ai->ai_socktype) {
1161 case SOCK_RAW:
1162 return EAI_SERVICE;
1163 case SOCK_DGRAM:
1164 case SOCK_STREAM:
1165 allownumeric = 1;
1166 break;
1167 case ANY:
1168 #if 1 /* ANDROID-SPECIFIC CHANGE TO MATCH GLIBC */
1169 allownumeric = 1;
1170 #else
1171 allownumeric = 0;
1172 #endif
1173 break;
1174 default:
1175 return EAI_SOCKTYPE;
1176 }
1177
1178 port = str2number(servname);
1179 if (port >= 0) {
1180 if (!allownumeric)
1181 return EAI_SERVICE;
1182 if (port < 0 || port > 65535)
1183 return EAI_SERVICE;
1184 port = htons(port);
1185 } else {
1186 if (ai->ai_flags & AI_NUMERICSERV)
1187 return EAI_NONAME;
1188
1189 switch (ai->ai_socktype) {
1190 case SOCK_DGRAM:
1191 proto = "udp";
1192 break;
1193 case SOCK_STREAM:
1194 proto = "tcp";
1195 break;
1196 default:
1197 proto = NULL;
1198 break;
1199 }
1200
1201 if ((sp = getservbyname(servname, proto)) == NULL)
1202 return EAI_SERVICE;
1203 port = sp->s_port;
1204 }
1205
1206 if (!matchonly) {
1207 switch (ai->ai_family) {
1208 case AF_INET:
1209 ((struct sockaddr_in *)(void *)
1210 ai->ai_addr)->sin_port = port;
1211 break;
1212 #ifdef INET6
1213 case AF_INET6:
1214 ((struct sockaddr_in6 *)(void *)
1215 ai->ai_addr)->sin6_port = port;
1216 break;
1217 #endif
1218 }
1219 }
1220
1221 return 0;
1222 }
1223
1224 static const struct afd *
find_afd(int af)1225 find_afd(int af)
1226 {
1227 const struct afd *afd;
1228
1229 if (af == PF_UNSPEC)
1230 return NULL;
1231 for (afd = afdl; afd->a_af; afd++) {
1232 if (afd->a_af == af)
1233 return afd;
1234 }
1235 return NULL;
1236 }
1237
1238 #ifdef INET6
1239 /* convert a string to a scope identifier. XXX: IPv6 specific */
1240 static int
ip6_str2scopeid(char * scope,struct sockaddr_in6 * sin6,u_int32_t * scopeid)1241 ip6_str2scopeid(char *scope, struct sockaddr_in6 *sin6, u_int32_t *scopeid)
1242 {
1243 u_long lscopeid;
1244 struct in6_addr *a6;
1245 char *ep;
1246
1247 assert(scope != NULL);
1248 assert(sin6 != NULL);
1249 assert(scopeid != NULL);
1250
1251 a6 = &sin6->sin6_addr;
1252
1253 /* empty scopeid portion is invalid */
1254 if (*scope == '\0')
1255 return -1;
1256
1257 if (IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6)) {
1258 /*
1259 * We currently assume a one-to-one mapping between links
1260 * and interfaces, so we simply use interface indices for
1261 * like-local scopes.
1262 */
1263 *scopeid = if_nametoindex(scope);
1264 if (*scopeid == 0)
1265 goto trynumeric;
1266 return 0;
1267 }
1268
1269 /* still unclear about literal, allow numeric only - placeholder */
1270 if (IN6_IS_ADDR_SITELOCAL(a6) || IN6_IS_ADDR_MC_SITELOCAL(a6))
1271 goto trynumeric;
1272 if (IN6_IS_ADDR_MC_ORGLOCAL(a6))
1273 goto trynumeric;
1274 else
1275 goto trynumeric; /* global */
1276
1277 /* try to convert to a numeric id as a last resort */
1278 trynumeric:
1279 errno = 0;
1280 lscopeid = strtoul(scope, &ep, 10);
1281 *scopeid = (u_int32_t)(lscopeid & 0xffffffffUL);
1282 if (errno == 0 && ep && *ep == '\0' && *scopeid == lscopeid)
1283 return 0;
1284 else
1285 return -1;
1286 }
1287 #endif
1288
1289 /* code duplicate with gethnamaddr.c */
1290
1291 static const char AskedForGot[] =
1292 "gethostby*.getanswer: asked for \"%s\", got \"%s\"";
1293
1294 static struct addrinfo *
getanswer(const querybuf * answer,int anslen,const char * qname,int qtype,const struct addrinfo * pai)1295 getanswer(const querybuf *answer, int anslen, const char *qname, int qtype,
1296 const struct addrinfo *pai)
1297 {
1298 struct addrinfo sentinel, *cur;
1299 struct addrinfo ai;
1300 const struct afd *afd;
1301 char *canonname;
1302 const HEADER *hp;
1303 const u_char *cp;
1304 int n;
1305 const u_char *eom;
1306 char *bp, *ep;
1307 int type, class, ancount, qdcount;
1308 int haveanswer, had_error;
1309 char tbuf[MAXDNAME];
1310 int (*name_ok) (const char *);
1311 char hostbuf[8*1024];
1312
1313 assert(answer != NULL);
1314 assert(qname != NULL);
1315 assert(pai != NULL);
1316
1317 memset(&sentinel, 0, sizeof(sentinel));
1318 cur = &sentinel;
1319
1320 canonname = NULL;
1321 eom = answer->buf + anslen;
1322 switch (qtype) {
1323 case T_A:
1324 case T_AAAA:
1325 case T_ANY: /*use T_ANY only for T_A/T_AAAA lookup*/
1326 name_ok = res_hnok;
1327 break;
1328 default:
1329 return NULL; /* XXX should be abort(); */
1330 }
1331 /*
1332 * find first satisfactory answer
1333 */
1334 hp = &answer->hdr;
1335 ancount = ntohs(hp->ancount);
1336 qdcount = ntohs(hp->qdcount);
1337 bp = hostbuf;
1338 ep = hostbuf + sizeof hostbuf;
1339 cp = answer->buf + HFIXEDSZ;
1340 if (qdcount != 1) {
1341 h_errno = NO_RECOVERY;
1342 return (NULL);
1343 }
1344 n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
1345 if ((n < 0) || !(*name_ok)(bp)) {
1346 h_errno = NO_RECOVERY;
1347 return (NULL);
1348 }
1349 cp += n + QFIXEDSZ;
1350 if (qtype == T_A || qtype == T_AAAA || qtype == T_ANY) {
1351 /* res_send() has already verified that the query name is the
1352 * same as the one we sent; this just gets the expanded name
1353 * (i.e., with the succeeding search-domain tacked on).
1354 */
1355 n = strlen(bp) + 1; /* for the \0 */
1356 if (n >= MAXHOSTNAMELEN) {
1357 h_errno = NO_RECOVERY;
1358 return (NULL);
1359 }
1360 canonname = bp;
1361 bp += n;
1362 /* The qname can be abbreviated, but h_name is now absolute. */
1363 qname = canonname;
1364 }
1365 haveanswer = 0;
1366 had_error = 0;
1367 while (ancount-- > 0 && cp < eom && !had_error) {
1368 n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
1369 if ((n < 0) || !(*name_ok)(bp)) {
1370 had_error++;
1371 continue;
1372 }
1373 cp += n; /* name */
1374 type = _getshort(cp);
1375 cp += INT16SZ; /* type */
1376 class = _getshort(cp);
1377 cp += INT16SZ + INT32SZ; /* class, TTL */
1378 n = _getshort(cp);
1379 cp += INT16SZ; /* len */
1380 if (class != C_IN) {
1381 /* XXX - debug? syslog? */
1382 cp += n;
1383 continue; /* XXX - had_error++ ? */
1384 }
1385 if ((qtype == T_A || qtype == T_AAAA || qtype == T_ANY) &&
1386 type == T_CNAME) {
1387 n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
1388 if ((n < 0) || !(*name_ok)(tbuf)) {
1389 had_error++;
1390 continue;
1391 }
1392 cp += n;
1393 /* Get canonical name. */
1394 n = strlen(tbuf) + 1; /* for the \0 */
1395 if (n > ep - bp || n >= MAXHOSTNAMELEN) {
1396 had_error++;
1397 continue;
1398 }
1399 strlcpy(bp, tbuf, (size_t)(ep - bp));
1400 canonname = bp;
1401 bp += n;
1402 continue;
1403 }
1404 if (qtype == T_ANY) {
1405 if (!(type == T_A || type == T_AAAA)) {
1406 cp += n;
1407 continue;
1408 }
1409 } else if (type != qtype) {
1410 if (type != T_KEY && type != T_SIG)
1411 syslog(LOG_NOTICE|LOG_AUTH,
1412 "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
1413 qname, p_class(C_IN), p_type(qtype),
1414 p_type(type));
1415 cp += n;
1416 continue; /* XXX - had_error++ ? */
1417 }
1418 switch (type) {
1419 case T_A:
1420 case T_AAAA:
1421 if (strcasecmp(canonname, bp) != 0) {
1422 syslog(LOG_NOTICE|LOG_AUTH,
1423 AskedForGot, canonname, bp);
1424 cp += n;
1425 continue; /* XXX - had_error++ ? */
1426 }
1427 if (type == T_A && n != INADDRSZ) {
1428 cp += n;
1429 continue;
1430 }
1431 if (type == T_AAAA && n != IN6ADDRSZ) {
1432 cp += n;
1433 continue;
1434 }
1435 if (type == T_AAAA) {
1436 struct in6_addr in6;
1437 memcpy(&in6, cp, IN6ADDRSZ);
1438 if (IN6_IS_ADDR_V4MAPPED(&in6)) {
1439 cp += n;
1440 continue;
1441 }
1442 }
1443 if (!haveanswer) {
1444 int nn;
1445
1446 canonname = bp;
1447 nn = strlen(bp) + 1; /* for the \0 */
1448 bp += nn;
1449 }
1450
1451 /* don't overwrite pai */
1452 ai = *pai;
1453 ai.ai_family = (type == T_A) ? AF_INET : AF_INET6;
1454 afd = find_afd(ai.ai_family);
1455 if (afd == NULL) {
1456 cp += n;
1457 continue;
1458 }
1459 cur->ai_next = get_ai(&ai, afd, (const char *)cp);
1460 if (cur->ai_next == NULL)
1461 had_error++;
1462 while (cur && cur->ai_next)
1463 cur = cur->ai_next;
1464 cp += n;
1465 break;
1466 default:
1467 abort();
1468 }
1469 if (!had_error)
1470 haveanswer++;
1471 }
1472 if (haveanswer) {
1473 if (!canonname)
1474 (void)get_canonname(pai, sentinel.ai_next, qname);
1475 else
1476 (void)get_canonname(pai, sentinel.ai_next, canonname);
1477 h_errno = NETDB_SUCCESS;
1478 return sentinel.ai_next;
1479 }
1480
1481 h_errno = NO_RECOVERY;
1482 return NULL;
1483 }
1484
1485 struct addrinfo_sort_elem {
1486 struct addrinfo *ai;
1487 int has_src_addr;
1488 sockaddr_union src_addr;
1489 int original_order;
1490 };
1491
1492 /*ARGSUSED*/
1493 static int
_get_scope(const struct sockaddr * addr)1494 _get_scope(const struct sockaddr *addr)
1495 {
1496 if (addr->sa_family == AF_INET6) {
1497 const struct sockaddr_in6 *addr6 = (const struct sockaddr_in6 *)addr;
1498 if (IN6_IS_ADDR_MULTICAST(&addr6->sin6_addr)) {
1499 return IPV6_ADDR_MC_SCOPE(&addr6->sin6_addr);
1500 } else if (IN6_IS_ADDR_LOOPBACK(&addr6->sin6_addr) ||
1501 IN6_IS_ADDR_LINKLOCAL(&addr6->sin6_addr)) {
1502 /*
1503 * RFC 4291 section 2.5.3 says loopback is to be treated as having
1504 * link-local scope.
1505 */
1506 return IPV6_ADDR_SCOPE_LINKLOCAL;
1507 } else if (IN6_IS_ADDR_SITELOCAL(&addr6->sin6_addr)) {
1508 return IPV6_ADDR_SCOPE_SITELOCAL;
1509 } else {
1510 return IPV6_ADDR_SCOPE_GLOBAL;
1511 }
1512 } else if (addr->sa_family == AF_INET) {
1513 const struct sockaddr_in *addr4 = (const struct sockaddr_in *)addr;
1514 unsigned long int na = ntohl(addr4->sin_addr.s_addr);
1515
1516 if (IN_LOOPBACK(na) || /* 127.0.0.0/8 */
1517 (na & 0xffff0000) == 0xa9fe0000) { /* 169.254.0.0/16 */
1518 return IPV6_ADDR_SCOPE_LINKLOCAL;
1519 } else {
1520 /*
1521 * RFC 6724 section 3.2. Other IPv4 addresses, including private addresses
1522 * and shared addresses (100.64.0.0/10), are assigned global scope.
1523 */
1524 return IPV6_ADDR_SCOPE_GLOBAL;
1525 }
1526 } else {
1527 /*
1528 * This should never happen.
1529 * Return a scope with low priority as a last resort.
1530 */
1531 return IPV6_ADDR_SCOPE_NODELOCAL;
1532 }
1533 }
1534
1535 /* These macros are modelled after the ones in <netinet/in6.h>. */
1536
1537 /* RFC 4380, section 2.6 */
1538 #define IN6_IS_ADDR_TEREDO(a) \
1539 ((*(const uint32_t *)(const void *)(&(a)->s6_addr[0]) == ntohl(0x20010000)))
1540
1541 /* RFC 3056, section 2. */
1542 #define IN6_IS_ADDR_6TO4(a) \
1543 (((a)->s6_addr[0] == 0x20) && ((a)->s6_addr[1] == 0x02))
1544
1545 /* 6bone testing address area (3ffe::/16), deprecated in RFC 3701. */
1546 #define IN6_IS_ADDR_6BONE(a) \
1547 (((a)->s6_addr[0] == 0x3f) && ((a)->s6_addr[1] == 0xfe))
1548
1549 /*
1550 * Get the label for a given IPv4/IPv6 address.
1551 * RFC 6724, section 2.1.
1552 */
1553
1554 /*ARGSUSED*/
1555 static int
_get_label(const struct sockaddr * addr)1556 _get_label(const struct sockaddr *addr)
1557 {
1558 if (addr->sa_family == AF_INET) {
1559 return 4;
1560 } else if (addr->sa_family == AF_INET6) {
1561 const struct sockaddr_in6 *addr6 = (const struct sockaddr_in6 *) addr;
1562 if (IN6_IS_ADDR_LOOPBACK(&addr6->sin6_addr)) {
1563 return 0;
1564 } else if (IN6_IS_ADDR_V4MAPPED(&addr6->sin6_addr)) {
1565 return 4;
1566 } else if (IN6_IS_ADDR_6TO4(&addr6->sin6_addr)) {
1567 return 2;
1568 } else if (IN6_IS_ADDR_TEREDO(&addr6->sin6_addr)) {
1569 return 5;
1570 } else if (IN6_IS_ADDR_ULA(&addr6->sin6_addr)) {
1571 return 13;
1572 } else if (IN6_IS_ADDR_V4COMPAT(&addr6->sin6_addr)) {
1573 return 3;
1574 } else if (IN6_IS_ADDR_SITELOCAL(&addr6->sin6_addr)) {
1575 return 11;
1576 } else if (IN6_IS_ADDR_6BONE(&addr6->sin6_addr)) {
1577 return 12;
1578 } else {
1579 /* All other IPv6 addresses, including global unicast addresses. */
1580 return 1;
1581 }
1582 } else {
1583 /*
1584 * This should never happen.
1585 * Return a semi-random label as a last resort.
1586 */
1587 return 1;
1588 }
1589 }
1590
1591 /*
1592 * Get the precedence for a given IPv4/IPv6 address.
1593 * RFC 6724, section 2.1.
1594 */
1595
1596 /*ARGSUSED*/
1597 static int
_get_precedence(const struct sockaddr * addr)1598 _get_precedence(const struct sockaddr *addr)
1599 {
1600 if (addr->sa_family == AF_INET) {
1601 return 35;
1602 } else if (addr->sa_family == AF_INET6) {
1603 const struct sockaddr_in6 *addr6 = (const struct sockaddr_in6 *)addr;
1604 if (IN6_IS_ADDR_LOOPBACK(&addr6->sin6_addr)) {
1605 return 50;
1606 } else if (IN6_IS_ADDR_V4MAPPED(&addr6->sin6_addr)) {
1607 return 35;
1608 } else if (IN6_IS_ADDR_6TO4(&addr6->sin6_addr)) {
1609 return 30;
1610 } else if (IN6_IS_ADDR_TEREDO(&addr6->sin6_addr)) {
1611 return 5;
1612 } else if (IN6_IS_ADDR_ULA(&addr6->sin6_addr)) {
1613 return 3;
1614 } else if (IN6_IS_ADDR_V4COMPAT(&addr6->sin6_addr) ||
1615 IN6_IS_ADDR_SITELOCAL(&addr6->sin6_addr) ||
1616 IN6_IS_ADDR_6BONE(&addr6->sin6_addr)) {
1617 return 1;
1618 } else {
1619 /* All other IPv6 addresses, including global unicast addresses. */
1620 return 40;
1621 }
1622 } else {
1623 return 1;
1624 }
1625 }
1626
1627 /*
1628 * Find number of matching initial bits between the two addresses a1 and a2.
1629 */
1630
1631 /*ARGSUSED*/
1632 static int
_common_prefix_len(const struct in6_addr * a1,const struct in6_addr * a2)1633 _common_prefix_len(const struct in6_addr *a1, const struct in6_addr *a2)
1634 {
1635 const char *p1 = (const char *)a1;
1636 const char *p2 = (const char *)a2;
1637 unsigned i;
1638
1639 for (i = 0; i < sizeof(*a1); ++i) {
1640 int x, j;
1641
1642 if (p1[i] == p2[i]) {
1643 continue;
1644 }
1645 x = p1[i] ^ p2[i];
1646 for (j = 0; j < CHAR_BIT; ++j) {
1647 if (x & (1 << (CHAR_BIT - 1))) {
1648 return i * CHAR_BIT + j;
1649 }
1650 x <<= 1;
1651 }
1652 }
1653 return sizeof(*a1) * CHAR_BIT;
1654 }
1655
1656 /*
1657 * Compare two source/destination address pairs.
1658 * RFC 6724, section 6.
1659 */
1660
1661 /*ARGSUSED*/
1662 static int
_rfc6724_compare(const void * ptr1,const void * ptr2)1663 _rfc6724_compare(const void *ptr1, const void* ptr2)
1664 {
1665 const struct addrinfo_sort_elem *a1 = (const struct addrinfo_sort_elem *)ptr1;
1666 const struct addrinfo_sort_elem *a2 = (const struct addrinfo_sort_elem *)ptr2;
1667 int scope_src1, scope_dst1, scope_match1;
1668 int scope_src2, scope_dst2, scope_match2;
1669 int label_src1, label_dst1, label_match1;
1670 int label_src2, label_dst2, label_match2;
1671 int precedence1, precedence2;
1672 int prefixlen1, prefixlen2;
1673
1674 /* Rule 1: Avoid unusable destinations. */
1675 if (a1->has_src_addr != a2->has_src_addr) {
1676 return a2->has_src_addr - a1->has_src_addr;
1677 }
1678
1679 /* Rule 2: Prefer matching scope. */
1680 scope_src1 = _get_scope(&a1->src_addr.generic);
1681 scope_dst1 = _get_scope(a1->ai->ai_addr);
1682 scope_match1 = (scope_src1 == scope_dst1);
1683
1684 scope_src2 = _get_scope(&a2->src_addr.generic);
1685 scope_dst2 = _get_scope(a2->ai->ai_addr);
1686 scope_match2 = (scope_src2 == scope_dst2);
1687
1688 if (scope_match1 != scope_match2) {
1689 return scope_match2 - scope_match1;
1690 }
1691
1692 /*
1693 * Rule 3: Avoid deprecated addresses.
1694 * TODO(sesse): We don't currently have a good way of finding this.
1695 */
1696
1697 /*
1698 * Rule 4: Prefer home addresses.
1699 * TODO(sesse): We don't currently have a good way of finding this.
1700 */
1701
1702 /* Rule 5: Prefer matching label. */
1703 label_src1 = _get_label(&a1->src_addr.generic);
1704 label_dst1 = _get_label(a1->ai->ai_addr);
1705 label_match1 = (label_src1 == label_dst1);
1706
1707 label_src2 = _get_label(&a2->src_addr.generic);
1708 label_dst2 = _get_label(a2->ai->ai_addr);
1709 label_match2 = (label_src2 == label_dst2);
1710
1711 if (label_match1 != label_match2) {
1712 return label_match2 - label_match1;
1713 }
1714
1715 /* Rule 6: Prefer higher precedence. */
1716 precedence1 = _get_precedence(a1->ai->ai_addr);
1717 precedence2 = _get_precedence(a2->ai->ai_addr);
1718 if (precedence1 != precedence2) {
1719 return precedence2 - precedence1;
1720 }
1721
1722 /*
1723 * Rule 7: Prefer native transport.
1724 * TODO(sesse): We don't currently have a good way of finding this.
1725 */
1726
1727 /* Rule 8: Prefer smaller scope. */
1728 if (scope_dst1 != scope_dst2) {
1729 return scope_dst1 - scope_dst2;
1730 }
1731
1732 /*
1733 * Rule 9: Use longest matching prefix.
1734 * We implement this for IPv6 only, as the rules in RFC 6724 don't seem
1735 * to work very well directly applied to IPv4. (glibc uses information from
1736 * the routing table for a custom IPv4 implementation here.)
1737 */
1738 if (a1->has_src_addr && a1->ai->ai_addr->sa_family == AF_INET6 &&
1739 a2->has_src_addr && a2->ai->ai_addr->sa_family == AF_INET6) {
1740 const struct sockaddr_in6 *a1_src = &a1->src_addr.in6;
1741 const struct sockaddr_in6 *a1_dst = (const struct sockaddr_in6 *)a1->ai->ai_addr;
1742 const struct sockaddr_in6 *a2_src = &a2->src_addr.in6;
1743 const struct sockaddr_in6 *a2_dst = (const struct sockaddr_in6 *)a2->ai->ai_addr;
1744 prefixlen1 = _common_prefix_len(&a1_src->sin6_addr, &a1_dst->sin6_addr);
1745 prefixlen2 = _common_prefix_len(&a2_src->sin6_addr, &a2_dst->sin6_addr);
1746 if (prefixlen1 != prefixlen2) {
1747 return prefixlen2 - prefixlen1;
1748 }
1749 }
1750
1751 /*
1752 * Rule 10: Leave the order unchanged.
1753 * We need this since qsort() is not necessarily stable.
1754 */
1755 return a1->original_order - a2->original_order;
1756 }
1757
1758 /*
1759 * Find the source address that will be used if trying to connect to the given
1760 * address. src_addr must be large enough to hold a struct sockaddr_in6.
1761 *
1762 * Returns 1 if a source address was found, 0 if the address is unreachable,
1763 * and -1 if a fatal error occurred. If 0 or 1, the contents of src_addr are
1764 * undefined.
1765 */
1766
1767 /*ARGSUSED*/
1768 static int
_find_src_addr(const struct sockaddr * addr,struct sockaddr * src_addr)1769 _find_src_addr(const struct sockaddr *addr, struct sockaddr *src_addr)
1770 {
1771 int sock;
1772 int ret;
1773 socklen_t len;
1774
1775 switch (addr->sa_family) {
1776 case AF_INET:
1777 len = sizeof(struct sockaddr_in);
1778 break;
1779 case AF_INET6:
1780 len = sizeof(struct sockaddr_in6);
1781 break;
1782 default:
1783 /* No known usable source address for non-INET families. */
1784 return 0;
1785 }
1786
1787 sock = socket(addr->sa_family, SOCK_DGRAM, IPPROTO_UDP);
1788 if (sock == -1) {
1789 if (errno == EAFNOSUPPORT) {
1790 return 0;
1791 } else {
1792 return -1;
1793 }
1794 }
1795
1796 do {
1797 ret = connect(sock, addr, len);
1798 } while (ret == -1 && errno == EINTR);
1799
1800 if (ret == -1) {
1801 close(sock);
1802 return 0;
1803 }
1804
1805 if (getsockname(sock, src_addr, &len) == -1) {
1806 close(sock);
1807 return -1;
1808 }
1809 close(sock);
1810 return 1;
1811 }
1812
1813 /*
1814 * Sort the linked list starting at sentinel->ai_next in RFC6724 order.
1815 * Will leave the list unchanged if an error occurs.
1816 */
1817
1818 /*ARGSUSED*/
1819 static void
_rfc6724_sort(struct addrinfo * list_sentinel)1820 _rfc6724_sort(struct addrinfo *list_sentinel)
1821 {
1822 struct addrinfo *cur;
1823 int nelem = 0, i;
1824 struct addrinfo_sort_elem *elems;
1825
1826 cur = list_sentinel->ai_next;
1827 while (cur) {
1828 ++nelem;
1829 cur = cur->ai_next;
1830 }
1831
1832 elems = (struct addrinfo_sort_elem *)malloc(nelem * sizeof(struct addrinfo_sort_elem));
1833 if (elems == NULL) {
1834 goto error;
1835 }
1836
1837 /*
1838 * Convert the linked list to an array that also contains the candidate
1839 * source address for each destination address.
1840 */
1841 for (i = 0, cur = list_sentinel->ai_next; i < nelem; ++i, cur = cur->ai_next) {
1842 int has_src_addr;
1843 assert(cur != NULL);
1844 elems[i].ai = cur;
1845 elems[i].original_order = i;
1846
1847 has_src_addr = _find_src_addr(cur->ai_addr, &elems[i].src_addr.generic);
1848 if (has_src_addr == -1) {
1849 goto error;
1850 }
1851 elems[i].has_src_addr = has_src_addr;
1852 }
1853
1854 /* Sort the addresses, and rearrange the linked list so it matches the sorted order. */
1855 qsort((void *)elems, nelem, sizeof(struct addrinfo_sort_elem), _rfc6724_compare);
1856
1857 list_sentinel->ai_next = elems[0].ai;
1858 for (i = 0; i < nelem - 1; ++i) {
1859 elems[i].ai->ai_next = elems[i + 1].ai;
1860 }
1861 elems[nelem - 1].ai->ai_next = NULL;
1862
1863 error:
1864 free(elems);
1865 }
1866
_using_alt_dns()1867 static int _using_alt_dns()
1868 {
1869 char propname[PROP_NAME_MAX];
1870 char propvalue[PROP_VALUE_MAX];
1871
1872 propvalue[0] = 0;
1873 snprintf(propname, sizeof(propname), "net.dns1.%d", getpid());
1874 if (__system_property_get(propname, propvalue) > 0 ) {
1875 return 1;
1876 }
1877 return 0;
1878 }
1879
1880 /*ARGSUSED*/
1881 static int
_dns_getaddrinfo(void * rv,void * cb_data,va_list ap)1882 _dns_getaddrinfo(void *rv, void *cb_data, va_list ap)
1883 {
1884 struct addrinfo *ai;
1885 querybuf *buf, *buf2;
1886 const char *name;
1887 const struct addrinfo *pai;
1888 struct addrinfo sentinel, *cur;
1889 struct res_target q, q2;
1890 res_state res;
1891 const char* iface;
1892
1893 name = va_arg(ap, char *);
1894 pai = va_arg(ap, const struct addrinfo *);
1895 iface = va_arg(ap, char *);
1896 //fprintf(stderr, "_dns_getaddrinfo() name = '%s'\n", name);
1897
1898 memset(&q, 0, sizeof(q));
1899 memset(&q2, 0, sizeof(q2));
1900 memset(&sentinel, 0, sizeof(sentinel));
1901 cur = &sentinel;
1902
1903 buf = malloc(sizeof(*buf));
1904 if (buf == NULL) {
1905 h_errno = NETDB_INTERNAL;
1906 return NS_NOTFOUND;
1907 }
1908 buf2 = malloc(sizeof(*buf2));
1909 if (buf2 == NULL) {
1910 free(buf);
1911 h_errno = NETDB_INTERNAL;
1912 return NS_NOTFOUND;
1913 }
1914
1915 switch (pai->ai_family) {
1916 case AF_UNSPEC:
1917 /* prefer IPv6 */
1918 q.name = name;
1919 q.qclass = C_IN;
1920 q.answer = buf->buf;
1921 q.anslen = sizeof(buf->buf);
1922 int query_ipv6 = 1, query_ipv4 = 1;
1923 if (pai->ai_flags & AI_ADDRCONFIG) {
1924 // Only implement AI_ADDRCONFIG if the application is not
1925 // using its own DNS servers, since our implementation
1926 // only works on the default connection.
1927 if (!_using_alt_dns()) {
1928 query_ipv6 = _have_ipv6();
1929 query_ipv4 = _have_ipv4();
1930 }
1931 }
1932 if (query_ipv6) {
1933 q.qtype = T_AAAA;
1934 if (query_ipv4) {
1935 q.next = &q2;
1936 q2.name = name;
1937 q2.qclass = C_IN;
1938 q2.qtype = T_A;
1939 q2.answer = buf2->buf;
1940 q2.anslen = sizeof(buf2->buf);
1941 }
1942 } else if (query_ipv4) {
1943 q.qtype = T_A;
1944 } else {
1945 free(buf);
1946 free(buf2);
1947 return NS_NOTFOUND;
1948 }
1949 break;
1950 case AF_INET:
1951 q.name = name;
1952 q.qclass = C_IN;
1953 q.qtype = T_A;
1954 q.answer = buf->buf;
1955 q.anslen = sizeof(buf->buf);
1956 break;
1957 case AF_INET6:
1958 q.name = name;
1959 q.qclass = C_IN;
1960 q.qtype = T_AAAA;
1961 q.answer = buf->buf;
1962 q.anslen = sizeof(buf->buf);
1963 break;
1964 default:
1965 free(buf);
1966 free(buf2);
1967 return NS_UNAVAIL;
1968 }
1969
1970 res = __res_get_state();
1971 if (res == NULL) {
1972 free(buf);
1973 free(buf2);
1974 return NS_NOTFOUND;
1975 }
1976
1977 /* this just sets our iface val in the thread private data so we don't have to
1978 * modify the api's all the way down to res_send.c's res_nsend. We could
1979 * fully populate the thread private data here, but if we get down there
1980 * and have a cache hit that would be wasted, so we do the rest there on miss
1981 */
1982 res_setiface(res, iface);
1983 if (res_searchN(name, &q, res) < 0) {
1984 __res_put_state(res);
1985 free(buf);
1986 free(buf2);
1987 return NS_NOTFOUND;
1988 }
1989 ai = getanswer(buf, q.n, q.name, q.qtype, pai);
1990 if (ai) {
1991 cur->ai_next = ai;
1992 while (cur && cur->ai_next)
1993 cur = cur->ai_next;
1994 }
1995 if (q.next) {
1996 ai = getanswer(buf2, q2.n, q2.name, q2.qtype, pai);
1997 if (ai)
1998 cur->ai_next = ai;
1999 }
2000 free(buf);
2001 free(buf2);
2002 if (sentinel.ai_next == NULL) {
2003 __res_put_state(res);
2004 switch (h_errno) {
2005 case HOST_NOT_FOUND:
2006 return NS_NOTFOUND;
2007 case TRY_AGAIN:
2008 return NS_TRYAGAIN;
2009 default:
2010 return NS_UNAVAIL;
2011 }
2012 }
2013
2014 _rfc6724_sort(&sentinel);
2015
2016 __res_put_state(res);
2017
2018 *((struct addrinfo **)rv) = sentinel.ai_next;
2019 return NS_SUCCESS;
2020 }
2021
2022 static void
_sethtent(FILE ** hostf)2023 _sethtent(FILE **hostf)
2024 {
2025
2026 if (!*hostf)
2027 *hostf = fopen(_PATH_HOSTS, "r" );
2028 else
2029 rewind(*hostf);
2030 }
2031
2032 static void
_endhtent(FILE ** hostf)2033 _endhtent(FILE **hostf)
2034 {
2035
2036 if (*hostf) {
2037 (void) fclose(*hostf);
2038 *hostf = NULL;
2039 }
2040 }
2041
2042 static struct addrinfo *
_gethtent(FILE ** hostf,const char * name,const struct addrinfo * pai)2043 _gethtent(FILE **hostf, const char *name, const struct addrinfo *pai)
2044 {
2045 char *p;
2046 char *cp, *tname, *cname;
2047 struct addrinfo hints, *res0, *res;
2048 int error;
2049 const char *addr;
2050 char hostbuf[8*1024];
2051
2052 // fprintf(stderr, "_gethtent() name = '%s'\n", name);
2053 assert(name != NULL);
2054 assert(pai != NULL);
2055
2056 if (!*hostf && !(*hostf = fopen(_PATH_HOSTS, "r" )))
2057 return (NULL);
2058 again:
2059 if (!(p = fgets(hostbuf, sizeof hostbuf, *hostf)))
2060 return (NULL);
2061 if (*p == '#')
2062 goto again;
2063 if (!(cp = strpbrk(p, "#\n")))
2064 goto again;
2065 *cp = '\0';
2066 if (!(cp = strpbrk(p, " \t")))
2067 goto again;
2068 *cp++ = '\0';
2069 addr = p;
2070 /* if this is not something we're looking for, skip it. */
2071 cname = NULL;
2072 while (cp && *cp) {
2073 if (*cp == ' ' || *cp == '\t') {
2074 cp++;
2075 continue;
2076 }
2077 if (!cname)
2078 cname = cp;
2079 tname = cp;
2080 if ((cp = strpbrk(cp, " \t")) != NULL)
2081 *cp++ = '\0';
2082 // fprintf(stderr, "\ttname = '%s'", tname);
2083 if (strcasecmp(name, tname) == 0)
2084 goto found;
2085 }
2086 goto again;
2087
2088 found:
2089 hints = *pai;
2090 hints.ai_flags = AI_NUMERICHOST;
2091 error = getaddrinfo(addr, NULL, &hints, &res0);
2092 if (error)
2093 goto again;
2094 for (res = res0; res; res = res->ai_next) {
2095 /* cover it up */
2096 res->ai_flags = pai->ai_flags;
2097
2098 if (pai->ai_flags & AI_CANONNAME) {
2099 if (get_canonname(pai, res, cname) != 0) {
2100 freeaddrinfo(res0);
2101 goto again;
2102 }
2103 }
2104 }
2105 return res0;
2106 }
2107
2108 /*ARGSUSED*/
2109 static int
_files_getaddrinfo(void * rv,void * cb_data,va_list ap)2110 _files_getaddrinfo(void *rv, void *cb_data, va_list ap)
2111 {
2112 const char *name;
2113 const struct addrinfo *pai;
2114 struct addrinfo sentinel, *cur;
2115 struct addrinfo *p;
2116 FILE *hostf = NULL;
2117
2118 name = va_arg(ap, char *);
2119 pai = va_arg(ap, struct addrinfo *);
2120
2121 // fprintf(stderr, "_files_getaddrinfo() name = '%s'\n", name);
2122 memset(&sentinel, 0, sizeof(sentinel));
2123 cur = &sentinel;
2124
2125 _sethtent(&hostf);
2126 while ((p = _gethtent(&hostf, name, pai)) != NULL) {
2127 cur->ai_next = p;
2128 while (cur && cur->ai_next)
2129 cur = cur->ai_next;
2130 }
2131 _endhtent(&hostf);
2132
2133 *((struct addrinfo **)rv) = sentinel.ai_next;
2134 if (sentinel.ai_next == NULL)
2135 return NS_NOTFOUND;
2136 return NS_SUCCESS;
2137 }
2138
2139 /* resolver logic */
2140
2141 /*
2142 * Formulate a normal query, send, and await answer.
2143 * Returned answer is placed in supplied buffer "answer".
2144 * Perform preliminary check of answer, returning success only
2145 * if no error is indicated and the answer count is nonzero.
2146 * Return the size of the response on success, -1 on error.
2147 * Error number is left in h_errno.
2148 *
2149 * Caller must parse answer and determine whether it answers the question.
2150 */
2151 static int
res_queryN(const char * name,struct res_target * target,res_state res)2152 res_queryN(const char *name, /* domain name */ struct res_target *target,
2153 res_state res)
2154 {
2155 u_char buf[MAXPACKET];
2156 HEADER *hp;
2157 int n;
2158 struct res_target *t;
2159 int rcode;
2160 int ancount;
2161
2162 assert(name != NULL);
2163 /* XXX: target may be NULL??? */
2164
2165 rcode = NOERROR;
2166 ancount = 0;
2167
2168 for (t = target; t; t = t->next) {
2169 int class, type;
2170 u_char *answer;
2171 int anslen;
2172
2173 hp = (HEADER *)(void *)t->answer;
2174 hp->rcode = NOERROR; /* default */
2175
2176 /* make it easier... */
2177 class = t->qclass;
2178 type = t->qtype;
2179 answer = t->answer;
2180 anslen = t->anslen;
2181 #ifdef DEBUG
2182 if (res->options & RES_DEBUG)
2183 printf(";; res_nquery(%s, %d, %d)\n", name, class, type);
2184 #endif
2185
2186 n = res_nmkquery(res, QUERY, name, class, type, NULL, 0, NULL,
2187 buf, sizeof(buf));
2188 #ifdef RES_USE_EDNS0
2189 if (n > 0 && (res->options & RES_USE_EDNS0) != 0)
2190 n = res_nopt(res, n, buf, sizeof(buf), anslen);
2191 #endif
2192 if (n <= 0) {
2193 #ifdef DEBUG
2194 if (res->options & RES_DEBUG)
2195 printf(";; res_nquery: mkquery failed\n");
2196 #endif
2197 h_errno = NO_RECOVERY;
2198 return n;
2199 }
2200 n = res_nsend(res, buf, n, answer, anslen);
2201 #if 0
2202 if (n < 0) {
2203 #ifdef DEBUG
2204 if (res->options & RES_DEBUG)
2205 printf(";; res_query: send error\n");
2206 #endif
2207 h_errno = TRY_AGAIN;
2208 return n;
2209 }
2210 #endif
2211
2212 if (n < 0 || hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
2213 rcode = hp->rcode; /* record most recent error */
2214 #ifdef DEBUG
2215 if (res->options & RES_DEBUG)
2216 printf(";; rcode = %u, ancount=%u\n", hp->rcode,
2217 ntohs(hp->ancount));
2218 #endif
2219 continue;
2220 }
2221
2222 ancount += ntohs(hp->ancount);
2223
2224 t->n = n;
2225 }
2226
2227 if (ancount == 0) {
2228 switch (rcode) {
2229 case NXDOMAIN:
2230 h_errno = HOST_NOT_FOUND;
2231 break;
2232 case SERVFAIL:
2233 h_errno = TRY_AGAIN;
2234 break;
2235 case NOERROR:
2236 h_errno = NO_DATA;
2237 break;
2238 case FORMERR:
2239 case NOTIMP:
2240 case REFUSED:
2241 default:
2242 h_errno = NO_RECOVERY;
2243 break;
2244 }
2245 return -1;
2246 }
2247 return ancount;
2248 }
2249
2250 /*
2251 * Formulate a normal query, send, and retrieve answer in supplied buffer.
2252 * Return the size of the response on success, -1 on error.
2253 * If enabled, implement search rules until answer or unrecoverable failure
2254 * is detected. Error code, if any, is left in h_errno.
2255 */
2256 static int
res_searchN(const char * name,struct res_target * target,res_state res)2257 res_searchN(const char *name, struct res_target *target, res_state res)
2258 {
2259 const char *cp, * const *domain;
2260 HEADER *hp;
2261 u_int dots;
2262 int trailing_dot, ret, saved_herrno;
2263 int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
2264
2265 assert(name != NULL);
2266 assert(target != NULL);
2267
2268 hp = (HEADER *)(void *)target->answer; /*XXX*/
2269
2270 errno = 0;
2271 h_errno = HOST_NOT_FOUND; /* default, if we never query */
2272 dots = 0;
2273 for (cp = name; *cp; cp++)
2274 dots += (*cp == '.');
2275 trailing_dot = 0;
2276 if (cp > name && *--cp == '.')
2277 trailing_dot++;
2278
2279
2280 //fprintf(stderr, "res_searchN() name = '%s'\n", name);
2281
2282 /*
2283 * if there aren't any dots, it could be a user-level alias
2284 */
2285 if (!dots && (cp = __hostalias(name)) != NULL) {
2286 ret = res_queryN(cp, target, res);
2287 return ret;
2288 }
2289
2290 /*
2291 * If there are dots in the name already, let's just give it a try
2292 * 'as is'. The threshold can be set with the "ndots" option.
2293 */
2294 saved_herrno = -1;
2295 if (dots >= res->ndots) {
2296 ret = res_querydomainN(name, NULL, target, res);
2297 if (ret > 0)
2298 return (ret);
2299 saved_herrno = h_errno;
2300 tried_as_is++;
2301 }
2302
2303 /*
2304 * We do at least one level of search if
2305 * - there is no dot and RES_DEFNAME is set, or
2306 * - there is at least one dot, there is no trailing dot,
2307 * and RES_DNSRCH is set.
2308 */
2309 if ((!dots && (res->options & RES_DEFNAMES)) ||
2310 (dots && !trailing_dot && (res->options & RES_DNSRCH))) {
2311 int done = 0;
2312
2313 for (domain = (const char * const *)res->dnsrch;
2314 *domain && !done;
2315 domain++) {
2316
2317 ret = res_querydomainN(name, *domain, target, res);
2318 if (ret > 0)
2319 return ret;
2320
2321 /*
2322 * If no server present, give up.
2323 * If name isn't found in this domain,
2324 * keep trying higher domains in the search list
2325 * (if that's enabled).
2326 * On a NO_DATA error, keep trying, otherwise
2327 * a wildcard entry of another type could keep us
2328 * from finding this entry higher in the domain.
2329 * If we get some other error (negative answer or
2330 * server failure), then stop searching up,
2331 * but try the input name below in case it's
2332 * fully-qualified.
2333 */
2334 if (errno == ECONNREFUSED) {
2335 h_errno = TRY_AGAIN;
2336 return -1;
2337 }
2338
2339 switch (h_errno) {
2340 case NO_DATA:
2341 got_nodata++;
2342 /* FALLTHROUGH */
2343 case HOST_NOT_FOUND:
2344 /* keep trying */
2345 break;
2346 case TRY_AGAIN:
2347 if (hp->rcode == SERVFAIL) {
2348 /* try next search element, if any */
2349 got_servfail++;
2350 break;
2351 }
2352 /* FALLTHROUGH */
2353 default:
2354 /* anything else implies that we're done */
2355 done++;
2356 }
2357 /*
2358 * if we got here for some reason other than DNSRCH,
2359 * we only wanted one iteration of the loop, so stop.
2360 */
2361 if (!(res->options & RES_DNSRCH))
2362 done++;
2363 }
2364 }
2365
2366 /*
2367 * if we have not already tried the name "as is", do that now.
2368 * note that we do this regardless of how many dots were in the
2369 * name or whether it ends with a dot.
2370 */
2371 if (!tried_as_is) {
2372 ret = res_querydomainN(name, NULL, target, res);
2373 if (ret > 0)
2374 return ret;
2375 }
2376
2377 /*
2378 * if we got here, we didn't satisfy the search.
2379 * if we did an initial full query, return that query's h_errno
2380 * (note that we wouldn't be here if that query had succeeded).
2381 * else if we ever got a nodata, send that back as the reason.
2382 * else send back meaningless h_errno, that being the one from
2383 * the last DNSRCH we did.
2384 */
2385 if (saved_herrno != -1)
2386 h_errno = saved_herrno;
2387 else if (got_nodata)
2388 h_errno = NO_DATA;
2389 else if (got_servfail)
2390 h_errno = TRY_AGAIN;
2391 return -1;
2392 }
2393
2394 /*
2395 * Perform a call on res_query on the concatenation of name and domain,
2396 * removing a trailing dot from name if domain is NULL.
2397 */
2398 static int
res_querydomainN(const char * name,const char * domain,struct res_target * target,res_state res)2399 res_querydomainN(const char *name, const char *domain,
2400 struct res_target *target, res_state res)
2401 {
2402 char nbuf[MAXDNAME];
2403 const char *longname = nbuf;
2404 size_t n, d;
2405
2406 assert(name != NULL);
2407 /* XXX: target may be NULL??? */
2408
2409 #ifdef DEBUG
2410 if (res->options & RES_DEBUG)
2411 printf(";; res_querydomain(%s, %s)\n",
2412 name, domain?domain:"<Nil>");
2413 #endif
2414 if (domain == NULL) {
2415 /*
2416 * Check for trailing '.';
2417 * copy without '.' if present.
2418 */
2419 n = strlen(name);
2420 if (n + 1 > sizeof(nbuf)) {
2421 h_errno = NO_RECOVERY;
2422 return -1;
2423 }
2424 if (n > 0 && name[--n] == '.') {
2425 strncpy(nbuf, name, n);
2426 nbuf[n] = '\0';
2427 } else
2428 longname = name;
2429 } else {
2430 n = strlen(name);
2431 d = strlen(domain);
2432 if (n + 1 + d + 1 > sizeof(nbuf)) {
2433 h_errno = NO_RECOVERY;
2434 return -1;
2435 }
2436 snprintf(nbuf, sizeof(nbuf), "%s.%s", name, domain);
2437 }
2438 return res_queryN(longname, target, res);
2439 }
2440