1 /* $NetBSD: gethnamaddr.c,v 1.91 2014/06/19 15:08:18 christos Exp $ */
2
3 /*
4 * ++Copyright++ 1985, 1988, 1993
5 * -
6 * Copyright (c) 1985, 1988, 1993
7 * The Regents of the University of California. All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 * -
33 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
34 *
35 * Permission to use, copy, modify, and distribute this software for any
36 * purpose with or without fee is hereby granted, provided that the above
37 * copyright notice and this permission notice appear in all copies, and that
38 * the name of Digital Equipment Corporation not be used in advertising or
39 * publicity pertaining to distribution of the document or software without
40 * specific, written prior permission.
41 *
42 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
43 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
44 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
45 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
46 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
47 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
48 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
49 * SOFTWARE.
50 * -
51 * --Copyright--
52 */
53
54 #include "gethnamaddr.h"
55
56 #include <android-base/logging.h>
57 #include <arpa/inet.h>
58 #include <arpa/nameser.h>
59 #include <assert.h>
60 #include <ctype.h>
61 #include <errno.h>
62 #include <netdb.h>
63 #include <netinet/in.h>
64 #include <stdarg.h>
65 #include <stdbool.h>
66 #include <stdlib.h>
67 #include <string.h>
68 #include <sys/param.h>
69 #include <sys/socket.h>
70 #include <sys/un.h>
71 #include <unistd.h>
72 #include <functional>
73 #include <vector>
74
75 #include "hostent.h"
76 #include "netd_resolv/resolv.h"
77 #include "res_comp.h"
78 #include "res_debug.h" // p_class(), p_type()
79 #include "resolv_cache.h"
80 #include "resolv_private.h"
81 #include "stats.pb.h"
82
83 using android::net::NetworkDnsEventReported;
84
85 // NetBSD uses _DIAGASSERT to null-check arguments and the like,
86 // but it's clear from the number of mistakes in their assertions
87 // that they don't actually test or ship with this.
88 #define _DIAGASSERT(e) /* nothing */
89
90 // TODO: unify macro ALIGNBYTES and ALIGN for all possible data type alignment of hostent
91 // buffer.
92 #define ALIGNBYTES (sizeof(uintptr_t) - 1)
93 #define ALIGN(p) (((uintptr_t)(p) + ALIGNBYTES) & ~ALIGNBYTES)
94
95 constexpr int MAXADDRS = 35;
96
97 typedef union {
98 HEADER hdr;
99 uint8_t buf[MAXPACKET];
100 } querybuf;
101
102 typedef union {
103 int32_t al;
104 char ac;
105 } align;
106
107 static void convert_v4v6_hostent(struct hostent* hp, char** bpp, char* ep,
108 const std::function<void(struct hostent* hp)>& mapping_param,
109 const std::function<void(char* src, char* dst)>& mapping_addr);
110 static void pad_v4v6_hostent(struct hostent* hp, char** bpp, char* ep);
111
112 static int dns_gethtbyaddr(const unsigned char* uaddr, int len, int af,
113 const android_net_context* netcontext, getnamaddr* info,
114 NetworkDnsEventReported* event);
115 static int dns_gethtbyname(ResState* res, const char* name, int af, getnamaddr* info);
116
117 #define BOUNDED_INCR(x) \
118 do { \
119 BOUNDS_CHECK(cp, x); \
120 cp += (x); \
121 } while (0)
122
123 #define BOUNDS_CHECK(ptr, count) \
124 do { \
125 if (eom - (ptr) < (count)) goto no_recovery; \
126 } while (0)
127
getanswer(const querybuf * answer,int anslen,const char * qname,int qtype,struct hostent * hent,char * buf,size_t buflen,int * he)128 static struct hostent* getanswer(const querybuf* answer, int anslen, const char* qname, int qtype,
129 struct hostent* hent, char* buf, size_t buflen, int* he) {
130 const HEADER* hp;
131 const uint8_t* cp;
132 int n;
133 size_t qlen;
134 const uint8_t *eom, *erdata;
135 char *bp, **hap, *ep;
136 int ancount, qdcount;
137 int haveanswer, had_error;
138 int toobig = 0;
139 char tbuf[MAXDNAME];
140 char* addr_ptrs[MAXADDRS];
141 const char* tname;
142 std::vector<char*> aliases;
143
144 _DIAGASSERT(answer != NULL);
145 _DIAGASSERT(qname != NULL);
146
147 tname = qname;
148 hent->h_name = NULL;
149 eom = answer->buf + anslen;
150
151 bool (*name_ok)(const char* dn);
152 switch (qtype) {
153 case T_A:
154 case T_AAAA:
155 name_ok = res_hnok;
156 break;
157 case T_PTR:
158 name_ok = res_dnok;
159 break;
160 default:
161 *he = NO_RECOVERY;
162 return NULL; /* XXX should be abort(); */
163 }
164
165 /*
166 * find first satisfactory answer
167 */
168 hp = &answer->hdr;
169 ancount = ntohs(hp->ancount);
170 qdcount = ntohs(hp->qdcount);
171 bp = buf;
172 ep = buf + buflen;
173 cp = answer->buf;
174 BOUNDED_INCR(HFIXEDSZ);
175 if (qdcount != 1) goto no_recovery;
176
177 n = dn_expand(answer->buf, eom, cp, bp, (int) (ep - bp));
178 if ((n < 0) || !name_ok(bp)) goto no_recovery;
179
180 BOUNDED_INCR(n + QFIXEDSZ);
181 if (qtype == T_A || qtype == T_AAAA) {
182 /* res_send() has already verified that the query name is the
183 * same as the one we sent; this just gets the expanded name
184 * (i.e., with the succeeding search-domain tacked on).
185 */
186 n = (int) strlen(bp) + 1; /* for the \0 */
187 if (n >= MAXHOSTNAMELEN) goto no_recovery;
188 hent->h_name = bp;
189 bp += n;
190 /* The qname can be abbreviated, but h_name is now absolute. */
191 qname = hent->h_name;
192 }
193 hent->h_addr_list = hap = addr_ptrs;
194 *hap = NULL;
195 haveanswer = 0;
196 had_error = 0;
197 while (ancount-- > 0 && cp < eom && !had_error) {
198 n = dn_expand(answer->buf, eom, cp, bp, (int) (ep - bp));
199 if ((n < 0) || !name_ok(bp)) {
200 had_error++;
201 continue;
202 }
203 cp += n; /* name */
204 BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
205 int type = ntohs(*reinterpret_cast<const uint16_t*>(cp));
206 cp += INT16SZ; /* type */
207 int cl = ntohs(*reinterpret_cast<const uint16_t*>(cp));
208 cp += INT16SZ + INT32SZ; /* class, TTL */
209 n = ntohs(*reinterpret_cast<const uint16_t*>(cp));
210 cp += INT16SZ; /* len */
211 BOUNDS_CHECK(cp, n);
212 erdata = cp + n;
213 if (cl != C_IN) {
214 /* XXX - debug? syslog? */
215 cp += n;
216 continue; /* XXX - had_error++ ? */
217 }
218 if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
219 n = dn_expand(answer->buf, eom, cp, tbuf, (int) sizeof tbuf);
220 if ((n < 0) || !name_ok(tbuf)) {
221 had_error++;
222 continue;
223 }
224 cp += n;
225 if (cp != erdata) goto no_recovery;
226 /* Store alias. */
227 aliases.push_back(bp);
228 n = (int) strlen(bp) + 1; /* for the \0 */
229 if (n >= MAXHOSTNAMELEN) {
230 had_error++;
231 continue;
232 }
233 bp += n;
234 /* Get canonical name. */
235 n = (int) strlen(tbuf) + 1; /* for the \0 */
236 if (n > ep - bp || n >= MAXHOSTNAMELEN) {
237 had_error++;
238 continue;
239 }
240 strlcpy(bp, tbuf, (size_t)(ep - bp));
241 hent->h_name = bp;
242 bp += n;
243 continue;
244 }
245 if (qtype == T_PTR && type == T_CNAME) {
246 n = dn_expand(answer->buf, eom, cp, tbuf, (int) sizeof tbuf);
247 if (n < 0 || !res_dnok(tbuf)) {
248 had_error++;
249 continue;
250 }
251 cp += n;
252 if (cp != erdata) goto no_recovery;
253 /* Get canonical name. */
254 n = (int) strlen(tbuf) + 1; /* for the \0 */
255 if (n > ep - bp || n >= MAXHOSTNAMELEN) {
256 had_error++;
257 continue;
258 }
259 strlcpy(bp, tbuf, (size_t)(ep - bp));
260 tname = bp;
261 bp += n;
262 continue;
263 }
264 if (type != qtype) {
265 if (type != T_KEY && type != T_SIG)
266 LOG(DEBUG) << __func__ << ": asked for \"" << qname << " " << p_class(C_IN) << " "
267 << p_type(qtype) << "\", got type \"" << p_type(type) << "\"";
268 cp += n;
269 continue; /* XXX - had_error++ ? */
270 }
271 switch (type) {
272 case T_PTR:
273 if (strcasecmp(tname, bp) != 0) {
274 LOG(DEBUG) << __func__ << ": asked for \"" << qname << "\", got \"" << bp
275 << "\"";
276 cp += n;
277 continue; /* XXX - had_error++ ? */
278 }
279 n = dn_expand(answer->buf, eom, cp, bp, (int) (ep - bp));
280 if ((n < 0) || !res_hnok(bp)) {
281 had_error++;
282 break;
283 }
284 cp += n;
285 if (cp != erdata) goto no_recovery;
286 if (!haveanswer)
287 hent->h_name = bp;
288 else
289 aliases.push_back(bp);
290 if (n != -1) {
291 n = (int) strlen(bp) + 1; /* for the \0 */
292 if (n >= MAXHOSTNAMELEN) {
293 had_error++;
294 break;
295 }
296 bp += n;
297 }
298 break;
299 case T_A:
300 case T_AAAA:
301 if (strcasecmp(hent->h_name, bp) != 0) {
302 LOG(DEBUG) << __func__ << ": asked for \"" << hent->h_name << "\", got \"" << bp
303 << "\"";
304 cp += n;
305 continue; /* XXX - had_error++ ? */
306 }
307 if (n != hent->h_length) {
308 cp += n;
309 continue;
310 }
311 if (type == T_AAAA) {
312 struct in6_addr in6;
313 memcpy(&in6, cp, NS_IN6ADDRSZ);
314 if (IN6_IS_ADDR_V4MAPPED(&in6)) {
315 cp += n;
316 continue;
317 }
318 }
319 if (!haveanswer) {
320 int nn;
321
322 hent->h_name = bp;
323 nn = (int) strlen(bp) + 1; /* for the \0 */
324 bp += nn;
325 }
326
327 bp += sizeof(align) - (size_t)((uintptr_t)bp % sizeof(align));
328
329 if (bp + n >= ep) {
330 LOG(DEBUG) << __func__ << ": size (" << n << ") too big";
331 had_error++;
332 continue;
333 }
334 if (hap >= &addr_ptrs[MAXADDRS - 1]) {
335 if (!toobig++) {
336 LOG(DEBUG) << __func__ << ": Too many addresses (" << MAXADDRS << ")";
337 }
338 cp += n;
339 continue;
340 }
341 (void) memcpy(*hap++ = bp, cp, (size_t) n);
342 bp += n;
343 cp += n;
344 if (cp != erdata) goto no_recovery;
345 break;
346 default:
347 abort();
348 }
349 if (!had_error) haveanswer++;
350 }
351 if (haveanswer) {
352 *hap = NULL;
353 if (!hent->h_name) {
354 n = (int) strlen(qname) + 1; /* for the \0 */
355 if (n > ep - bp || n >= MAXHOSTNAMELEN) goto no_recovery;
356 strlcpy(bp, qname, (size_t)(ep - bp));
357 hent->h_name = bp;
358 bp += n;
359 }
360 if (hent->h_addrtype == AF_INET) pad_v4v6_hostent(hent, &bp, ep);
361 goto success;
362 }
363 no_recovery:
364 *he = NO_RECOVERY;
365 return NULL;
366 success:
367 bp = (char*) ALIGN(bp);
368 aliases.push_back(nullptr);
369 qlen = aliases.size() * sizeof(*hent->h_aliases);
370 if ((size_t)(ep - bp) < qlen) goto nospc;
371 hent->h_aliases = (char**) bp;
372 memcpy(bp, aliases.data(), qlen);
373
374 bp += qlen;
375 n = (int) (hap - addr_ptrs);
376 qlen = (n + 1) * sizeof(*hent->h_addr_list);
377 if ((size_t)(ep - bp) < qlen) goto nospc;
378 hent->h_addr_list = (char**) bp;
379 memcpy(bp, addr_ptrs, qlen);
380 *he = NETDB_SUCCESS;
381 return hent;
382 nospc:
383 errno = ENOSPC;
384 *he = NETDB_INTERNAL;
385 return NULL;
386 }
387
resolv_gethostbyname(const char * name,int af,hostent * hp,char * buf,size_t buflen,const android_net_context * netcontext,hostent ** result,NetworkDnsEventReported * event)388 int resolv_gethostbyname(const char* name, int af, hostent* hp, char* buf, size_t buflen,
389 const android_net_context* netcontext, hostent** result,
390 NetworkDnsEventReported* event) {
391 if (name == nullptr || hp == nullptr) {
392 return EAI_SYSTEM;
393 }
394
395 getnamaddr info;
396 ResState res(netcontext, event);
397
398 size_t size;
399 switch (af) {
400 case AF_INET:
401 size = NS_INADDRSZ;
402 break;
403 case AF_INET6:
404 size = NS_IN6ADDRSZ;
405 break;
406 default:
407 return EAI_FAMILY;
408 }
409 if (buflen < size) goto nospc;
410
411 hp->h_addrtype = af;
412 hp->h_length = (int) size;
413
414 /*
415 * disallow names consisting only of digits/dots, unless
416 * they end in a dot.
417 */
418 if (isdigit((uint8_t)name[0])) {
419 for (const char* cp = name;; ++cp) {
420 if (!*cp) {
421 if (*--cp == '.') break;
422 /*
423 * All-numeric, no dot at the end.
424 * Fake up a hostent as if we'd actually
425 * done a lookup.
426 */
427 goto fake;
428 }
429 if (!isdigit((uint8_t)*cp) && *cp != '.') break;
430 }
431 }
432 if ((isxdigit((uint8_t)name[0]) && strchr(name, ':') != NULL) || name[0] == ':') {
433 for (const char* cp = name;; ++cp) {
434 if (!*cp) {
435 if (*--cp == '.') break;
436 /*
437 * All-IPv6-legal, no dot at the end.
438 * Fake up a hostent as if we'd actually
439 * done a lookup.
440 */
441 goto fake;
442 }
443 if (!isxdigit((uint8_t)*cp) && *cp != ':' && *cp != '.') break;
444 }
445 }
446
447 info.hp = hp;
448 info.buf = buf;
449 info.buflen = buflen;
450 if (_hf_gethtbyname2(name, af, &info)) {
451 int error = dns_gethtbyname(&res, name, af, &info);
452 if (error != 0) return error;
453 }
454 *result = hp;
455 return 0;
456 nospc:
457 return EAI_MEMORY;
458 fake:
459 HENT_ARRAY(hp->h_addr_list, 1, buf, buflen);
460 HENT_ARRAY(hp->h_aliases, 0, buf, buflen);
461
462 hp->h_aliases[0] = NULL;
463 if (size > buflen) goto nospc;
464
465 if (inet_pton(af, name, buf) <= 0) {
466 return EAI_NODATA;
467 }
468 hp->h_addr_list[0] = buf;
469 hp->h_addr_list[1] = NULL;
470 buf += size;
471 buflen -= size;
472 HENT_SCOPY(hp->h_name, name, buf, buflen);
473 *result = hp;
474 return 0;
475 }
476
resolv_gethostbyaddr(const void * addr,socklen_t len,int af,hostent * hp,char * buf,size_t buflen,const struct android_net_context * netcontext,hostent ** result,NetworkDnsEventReported * event)477 int resolv_gethostbyaddr(const void* addr, socklen_t len, int af, hostent* hp, char* buf,
478 size_t buflen, const struct android_net_context* netcontext,
479 hostent** result, NetworkDnsEventReported* event) {
480 const uint8_t* uaddr = (const uint8_t*)addr;
481 socklen_t size;
482 struct getnamaddr info;
483
484 _DIAGASSERT(addr != NULL);
485
486 if (af == AF_INET6 && len == NS_IN6ADDRSZ &&
487 (IN6_IS_ADDR_LINKLOCAL((const struct in6_addr*) addr) ||
488 IN6_IS_ADDR_SITELOCAL((const struct in6_addr*) addr))) {
489 return EAI_NODATA;
490 }
491 if (af == AF_INET6 && len == NS_IN6ADDRSZ &&
492 (IN6_IS_ADDR_V4MAPPED((const struct in6_addr*) addr) ||
493 IN6_IS_ADDR_V4COMPAT((const struct in6_addr*) addr))) {
494 /* Unmap. */
495 uaddr += NS_IN6ADDRSZ - NS_INADDRSZ;
496 addr = uaddr;
497 af = AF_INET;
498 len = NS_INADDRSZ;
499 }
500 switch (af) {
501 case AF_INET:
502 size = NS_INADDRSZ;
503 break;
504 case AF_INET6:
505 size = NS_IN6ADDRSZ;
506 break;
507 default:
508 return EAI_FAMILY;
509 }
510 if (size != len) {
511 // TODO: Consider converting to a private extended EAI_* error code.
512 // Currently, the EAI_* value has no corresponding error code for invalid argument socket
513 // length. In order to not rely on errno, convert the original error code pair, EAI_SYSTEM
514 // and EINVAL, to EAI_FAIL.
515 return EAI_FAIL;
516 }
517 info.hp = hp;
518 info.buf = buf;
519 info.buflen = buflen;
520 if (_hf_gethtbyaddr(uaddr, len, af, &info)) {
521 int error = dns_gethtbyaddr(uaddr, len, af, netcontext, &info, event);
522 if (error != 0) return error;
523 }
524 *result = hp;
525 return 0;
526 }
527
528 // TODO: Consider leaving function without returning error code as _gethtent() does because
529 // the error code of the caller does not currently return to netd.
netbsd_gethostent_r(FILE * hf,struct hostent * hent,char * buf,size_t buflen,int * he)530 struct hostent* netbsd_gethostent_r(FILE* hf, struct hostent* hent, char* buf, size_t buflen,
531 int* he) {
532 char *name;
533 char* cp;
534 int af, len;
535 size_t anum;
536 struct in6_addr host_addr;
537 std::vector<char*> aliases;
538
539 if (hf == NULL) {
540 *he = NETDB_INTERNAL;
541 errno = EINVAL;
542 return NULL;
543 }
544 char* p = NULL;
545
546 // Allocate a new space to read file lines like upstream does.
547 const size_t line_buf_size = MAXPACKET;
548 if ((p = (char*) malloc(line_buf_size)) == NULL) {
549 goto nospc;
550 }
551 for (;;) {
552 if (!fgets(p, line_buf_size, hf)) {
553 free(p);
554 *he = HOST_NOT_FOUND;
555 return NULL;
556 }
557 if (*p == '#') {
558 continue;
559 }
560 if (!(cp = strpbrk(p, "#\n"))) {
561 continue;
562 }
563 *cp = '\0';
564 if (!(cp = strpbrk(p, " \t"))) continue;
565 *cp++ = '\0';
566 if (inet_pton(AF_INET6, p, &host_addr) > 0) {
567 af = AF_INET6;
568 len = NS_IN6ADDRSZ;
569 } else {
570 if (inet_pton(AF_INET, p, &host_addr) <= 0) continue;
571 af = AF_INET;
572 len = NS_INADDRSZ;
573 }
574
575 /* if this is not something we're looking for, skip it. */
576 if (hent->h_addrtype != 0 && hent->h_addrtype != af) continue;
577 if (hent->h_length != 0 && hent->h_length != len) continue;
578
579 while (*cp == ' ' || *cp == '\t') cp++;
580 if ((cp = strpbrk(name = cp, " \t")) != NULL) *cp++ = '\0';
581 while (cp && *cp) {
582 if (*cp == ' ' || *cp == '\t') {
583 cp++;
584 continue;
585 }
586 aliases.push_back(cp);
587 if ((cp = strpbrk(cp, " \t")) != NULL) *cp++ = '\0';
588 }
589 break;
590 }
591 hent->h_length = len;
592 hent->h_addrtype = af;
593 HENT_ARRAY(hent->h_addr_list, 1, buf, buflen);
594 anum = aliases.size();
595 HENT_ARRAY(hent->h_aliases, anum, buf, buflen);
596 HENT_COPY(hent->h_addr_list[0], &host_addr, hent->h_length, buf, buflen);
597 hent->h_addr_list[1] = NULL;
598
599 /* Reserve space for mapping IPv4 address to IPv6 address in place */
600 if (hent->h_addrtype == AF_INET) {
601 HENT_COPY(buf, NAT64_PAD, sizeof(NAT64_PAD), buf, buflen);
602 }
603
604 HENT_SCOPY(hent->h_name, name, buf, buflen);
605 for (size_t i = 0; i < anum; i++) HENT_SCOPY(hent->h_aliases[i], aliases[i], buf, buflen);
606 hent->h_aliases[anum] = NULL;
607 *he = NETDB_SUCCESS;
608 free(p);
609 return hent;
610 nospc:
611 free(p);
612 errno = ENOSPC;
613 *he = NETDB_INTERNAL;
614 return NULL;
615 }
616
convert_v4v6_hostent(struct hostent * hp,char ** bpp,char * ep,const std::function<void (struct hostent * hp)> & map_param,const std::function<void (char * src,char * dst)> & map_addr)617 static void convert_v4v6_hostent(struct hostent* hp, char** bpp, char* ep,
618 const std::function<void(struct hostent* hp)>& map_param,
619 const std::function<void(char* src, char* dst)>& map_addr) {
620 _DIAGASSERT(hp != NULL);
621 _DIAGASSERT(bpp != NULL);
622 _DIAGASSERT(ep != NULL);
623
624 if (hp->h_addrtype != AF_INET || hp->h_length != NS_INADDRSZ) return;
625 map_param(hp);
626 for (char** ap = hp->h_addr_list; *ap; ap++) {
627 int i = (int)(sizeof(align) - (size_t)((uintptr_t)*bpp % sizeof(align)));
628
629 if (ep - *bpp < (i + NS_IN6ADDRSZ)) {
630 /* Out of memory. Truncate address list here. XXX */
631 *ap = NULL;
632 return;
633 }
634 *bpp += i;
635 map_addr(*ap, *bpp);
636 *ap = *bpp;
637 *bpp += NS_IN6ADDRSZ;
638 }
639 }
640
641 /* Reserve space for mapping IPv4 address to IPv6 address in place */
pad_v4v6_hostent(struct hostent * hp,char ** bpp,char * ep)642 static void pad_v4v6_hostent(struct hostent* hp, char** bpp, char* ep) {
643 convert_v4v6_hostent(hp, bpp, ep,
644 [](struct hostent* hp) {
645 (void) hp; /* unused */
646 },
647 [](char* src, char* dst) {
648 memcpy(dst, src, NS_INADDRSZ);
649 memcpy(dst + NS_INADDRSZ, NAT64_PAD, sizeof(NAT64_PAD));
650 });
651 }
652
dns_gethtbyname(ResState * res,const char * name,int addr_type,getnamaddr * info)653 static int dns_gethtbyname(ResState* res, const char* name, int addr_type, getnamaddr* info) {
654 int n, type;
655 info->hp->h_addrtype = addr_type;
656
657 switch (info->hp->h_addrtype) {
658 case AF_INET:
659 info->hp->h_length = NS_INADDRSZ;
660 type = T_A;
661 break;
662 case AF_INET6:
663 info->hp->h_length = NS_IN6ADDRSZ;
664 type = T_AAAA;
665 break;
666 default:
667 return EAI_FAMILY;
668 }
669 auto buf = std::make_unique<querybuf>();
670
671 int he;
672 n = res_nsearch(res, name, C_IN, type, buf->buf, (int)sizeof(buf->buf), &he);
673 if (n < 0) {
674 LOG(DEBUG) << __func__ << ": res_nsearch failed (" << n << ")";
675 // Return h_errno (he) to catch more detailed errors rather than EAI_NODATA.
676 // Note that res_nsearch() doesn't set the pair NETDB_INTERNAL and errno.
677 // See also herrnoToAiErrno().
678 return herrnoToAiErrno(he);
679 }
680 hostent* hp = getanswer(buf.get(), n, name, type, info->hp, info->buf, info->buflen, &he);
681 if (hp == NULL) return herrnoToAiErrno(he);
682
683 return 0;
684 }
685
dns_gethtbyaddr(const unsigned char * uaddr,int len,int af,const android_net_context * netcontext,getnamaddr * info,NetworkDnsEventReported * event)686 static int dns_gethtbyaddr(const unsigned char* uaddr, int len, int af,
687 const android_net_context* netcontext, getnamaddr* info,
688 NetworkDnsEventReported* event) {
689 char qbuf[MAXDNAME + 1], *qp, *ep;
690 int n;
691 int advance;
692
693 info->hp->h_length = len;
694 info->hp->h_addrtype = af;
695
696 switch (info->hp->h_addrtype) {
697 case AF_INET:
698 (void) snprintf(qbuf, sizeof(qbuf), "%u.%u.%u.%u.in-addr.arpa", (uaddr[3] & 0xff),
699 (uaddr[2] & 0xff), (uaddr[1] & 0xff), (uaddr[0] & 0xff));
700 break;
701
702 case AF_INET6:
703 qp = qbuf;
704 ep = qbuf + sizeof(qbuf) - 1;
705 for (n = NS_IN6ADDRSZ - 1; n >= 0; n--) {
706 advance = snprintf(qp, (size_t)(ep - qp), "%x.%x.", uaddr[n] & 0xf,
707 ((unsigned int) uaddr[n] >> 4) & 0xf);
708 if (advance > 0 && qp + advance < ep)
709 qp += advance;
710 else {
711 // TODO: Consider converting to a private extended EAI_* error code.
712 // Currently, the EAI_* value has no corresponding error code for an internal
713 // out of buffer space. In order to not rely on errno, convert the original
714 // error code EAI_SYSTEM to EAI_MEMORY.
715 return EAI_MEMORY;
716 }
717 }
718 if (strlcat(qbuf, "ip6.arpa", sizeof(qbuf)) >= sizeof(qbuf)) {
719 // TODO: Consider converting to a private extended EAI_* error code.
720 // Currently, the EAI_* value has no corresponding error code for an internal
721 // out of buffer space. In order to not rely on errno, convert the original
722 // error code EAI_SYSTEM to EAI_MEMORY.
723 return EAI_MEMORY;
724 }
725 break;
726 default:
727 return EAI_FAMILY;
728 }
729
730 auto buf = std::make_unique<querybuf>();
731
732 ResState res(netcontext, event);
733 int he;
734 n = res_nquery(&res, qbuf, C_IN, T_PTR, buf->buf, (int)sizeof(buf->buf), &he);
735 if (n < 0) {
736 LOG(DEBUG) << __func__ << ": res_nquery failed (" << n << ")";
737 // Note that res_nquery() doesn't set the pair NETDB_INTERNAL and errno.
738 // Return h_errno (he) to catch more detailed errors rather than EAI_NODATA.
739 // See also herrnoToAiErrno().
740 return herrnoToAiErrno(he);
741 }
742 hostent* hp = getanswer(buf.get(), n, qbuf, T_PTR, info->hp, info->buf, info->buflen, &he);
743 if (hp == NULL) return herrnoToAiErrno(he);
744
745 char* bf = (char*) (hp->h_addr_list + 2);
746 size_t blen = (size_t)(bf - info->buf);
747 if (blen + info->hp->h_length > info->buflen) goto nospc;
748 hp->h_addr_list[0] = bf;
749 hp->h_addr_list[1] = NULL;
750 memcpy(bf, uaddr, (size_t) info->hp->h_length);
751
752 /* Reserve enough space for mapping IPv4 address to IPv6 address in place */
753 if (info->hp->h_addrtype == AF_INET) {
754 if (blen + NS_IN6ADDRSZ > info->buflen) goto nospc;
755 // Pad zero to the unused address space
756 memcpy(bf + NS_INADDRSZ, NAT64_PAD, sizeof(NAT64_PAD));
757 }
758
759 return 0;
760
761 nospc:
762 return EAI_MEMORY;
763 }
764
herrnoToAiErrno(int he)765 int herrnoToAiErrno(int he) {
766 switch (he) {
767 // extended h_errno
768 case NETD_RESOLV_H_ERRNO_EXT_TIMEOUT:
769 return NETD_RESOLV_TIMEOUT;
770 // legacy h_errno
771 case NETDB_SUCCESS:
772 return 0;
773 case HOST_NOT_FOUND: // TODO: Perhaps convert HOST_NOT_FOUND to EAI_NONAME instead
774 case NO_DATA: // NO_ADDRESS
775 return EAI_NODATA;
776 case TRY_AGAIN:
777 return EAI_AGAIN;
778 case NETDB_INTERNAL:
779 // TODO: Remove ENOSPC and call abort() immediately whenever any allocation fails.
780 if (errno == ENOSPC) return EAI_MEMORY;
781 // Theoretically, this should not happen. Leave this here just in case.
782 // Currently, getanswer() of {gethnamaddr, getaddrinfo}.cpp, res_nsearch() and
783 // res_searchN() use this function to convert error code. Only getanswer()
784 // of gethnamaddr.cpp may return the error code pair, herrno NETDB_INTERNAL and
785 // errno ENOSPC, which has already converted to EAI_MEMORY. The remaining functions
786 // don't set the pair herrno and errno.
787 return EAI_SYSTEM; // see errno for detail
788 case NO_RECOVERY:
789 default:
790 return EAI_FAIL; // TODO: Perhaps convert default to EAI_MAX (unknown error) instead
791 }
792 }
793