1 | /* Copyright (C) 2016-2017 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | |
4 | The GNU C Library is free software; you can redistribute it and/or |
5 | modify it under the terms of the GNU Lesser General Public |
6 | License as published by the Free Software Foundation; either |
7 | version 2.1 of the License, or (at your option) any later version. |
8 | |
9 | The GNU C Library is distributed in the hope that it will be useful, |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
12 | Lesser General Public License for more details. |
13 | |
14 | You should have received a copy of the GNU Lesser General Public |
15 | License along with the GNU C Library; if not, see |
16 | <http://www.gnu.org/licenses/>. */ |
17 | |
18 | /* |
19 | * Copyright (c) 1985, 1989, 1993 |
20 | * The Regents of the University of California. All rights reserved. |
21 | * |
22 | * Redistribution and use in source and binary forms, with or without |
23 | * modification, are permitted provided that the following conditions |
24 | * are met: |
25 | * 1. Redistributions of source code must retain the above copyright |
26 | * notice, this list of conditions and the following disclaimer. |
27 | * 2. Redistributions in binary form must reproduce the above copyright |
28 | * notice, this list of conditions and the following disclaimer in the |
29 | * documentation and/or other materials provided with the distribution. |
30 | * 4. Neither the name of the University nor the names of its contributors |
31 | * may be used to endorse or promote products derived from this software |
32 | * without specific prior written permission. |
33 | * |
34 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
35 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
36 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
37 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
38 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
39 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
40 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
41 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
42 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
43 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
44 | * SUCH DAMAGE. |
45 | */ |
46 | |
47 | /* |
48 | * Portions Copyright (c) 1993 by Digital Equipment Corporation. |
49 | * |
50 | * Permission to use, copy, modify, and distribute this software for any |
51 | * purpose with or without fee is hereby granted, provided that the above |
52 | * copyright notice and this permission notice appear in all copies, and that |
53 | * the name of Digital Equipment Corporation not be used in advertising or |
54 | * publicity pertaining to distribution of the document or software without |
55 | * specific, written prior permission. |
56 | * |
57 | * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL |
58 | * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES |
59 | * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT |
60 | * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL |
61 | * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR |
62 | * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS |
63 | * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
64 | * SOFTWARE. |
65 | */ |
66 | |
67 | /* |
68 | * Portions Copyright (c) 1996-1999 by Internet Software Consortium. |
69 | * |
70 | * Permission to use, copy, modify, and distribute this software for any |
71 | * purpose with or without fee is hereby granted, provided that the above |
72 | * copyright notice and this permission notice appear in all copies. |
73 | * |
74 | * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS |
75 | * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES |
76 | * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE |
77 | * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL |
78 | * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR |
79 | * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS |
80 | * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
81 | * SOFTWARE. |
82 | */ |
83 | |
84 | /* |
85 | * Send query to name server and wait for reply. |
86 | */ |
87 | |
88 | #include <assert.h> |
89 | #include <sys/types.h> |
90 | #include <sys/param.h> |
91 | #include <sys/time.h> |
92 | #include <sys/socket.h> |
93 | #include <sys/uio.h> |
94 | #include <sys/poll.h> |
95 | |
96 | #include <netinet/in.h> |
97 | #include <arpa/nameser.h> |
98 | #include <arpa/inet.h> |
99 | #include <sys/ioctl.h> |
100 | |
101 | #include <errno.h> |
102 | #include <fcntl.h> |
103 | #include <netdb.h> |
104 | #include <resolv.h> |
105 | #include <signal.h> |
106 | #include <stdio.h> |
107 | #include <stdlib.h> |
108 | #include <string.h> |
109 | #include <unistd.h> |
110 | #include <kernel-features.h> |
111 | #include <libc-internal.h> |
112 | |
113 | #if PACKETSZ > 65536 |
114 | #define MAXPACKET PACKETSZ |
115 | #else |
116 | #define MAXPACKET 65536 |
117 | #endif |
118 | |
119 | /* From ev_streams.c. */ |
120 | |
121 | static inline void |
122 | __attribute ((always_inline)) |
123 | evConsIovec(void *buf, size_t cnt, struct iovec *vec) { |
124 | memset(vec, 0xf5, sizeof (*vec)); |
125 | vec->iov_base = buf; |
126 | vec->iov_len = cnt; |
127 | } |
128 | |
129 | /* From ev_timers.c. */ |
130 | |
131 | #define BILLION 1000000000 |
132 | |
133 | static inline void |
134 | evConsTime(struct timespec *res, time_t sec, long nsec) { |
135 | res->tv_sec = sec; |
136 | res->tv_nsec = nsec; |
137 | } |
138 | |
139 | static inline void |
140 | evAddTime(struct timespec *res, const struct timespec *addend1, |
141 | const struct timespec *addend2) { |
142 | res->tv_sec = addend1->tv_sec + addend2->tv_sec; |
143 | res->tv_nsec = addend1->tv_nsec + addend2->tv_nsec; |
144 | if (res->tv_nsec >= BILLION) { |
145 | res->tv_sec++; |
146 | res->tv_nsec -= BILLION; |
147 | } |
148 | } |
149 | |
150 | static inline void |
151 | evSubTime(struct timespec *res, const struct timespec *minuend, |
152 | const struct timespec *subtrahend) { |
153 | res->tv_sec = minuend->tv_sec - subtrahend->tv_sec; |
154 | if (minuend->tv_nsec >= subtrahend->tv_nsec) |
155 | res->tv_nsec = minuend->tv_nsec - subtrahend->tv_nsec; |
156 | else { |
157 | res->tv_nsec = (BILLION |
158 | - subtrahend->tv_nsec + minuend->tv_nsec); |
159 | res->tv_sec--; |
160 | } |
161 | } |
162 | |
163 | static int |
164 | evCmpTime(struct timespec a, struct timespec b) { |
165 | long x = a.tv_sec - b.tv_sec; |
166 | |
167 | if (x == 0L) |
168 | x = a.tv_nsec - b.tv_nsec; |
169 | return (x < 0L ? (-1) : x > 0L ? (1) : (0)); |
170 | } |
171 | |
172 | static void |
173 | evNowTime(struct timespec *res) { |
174 | struct timeval now; |
175 | |
176 | if (gettimeofday(&now, NULL) < 0) |
177 | evConsTime(res, 0, 0); |
178 | else |
179 | TIMEVAL_TO_TIMESPEC (&now, res); |
180 | } |
181 | |
182 | |
183 | /* Options. Leave them on. */ |
184 | /* #undef DEBUG */ |
185 | #include "res_debug.h" |
186 | |
187 | #define EXT(res) ((res)->_u._ext) |
188 | |
189 | /* Forward. */ |
190 | |
191 | static struct sockaddr *get_nsaddr (res_state, int); |
192 | static int send_vc(res_state, const u_char *, int, |
193 | const u_char *, int, |
194 | u_char **, int *, int *, int, u_char **, |
195 | u_char **, int *, int *, int *); |
196 | static int send_dg(res_state, const u_char *, int, |
197 | const u_char *, int, |
198 | u_char **, int *, int *, int, |
199 | int *, int *, u_char **, |
200 | u_char **, int *, int *, int *); |
201 | #ifdef DEBUG |
202 | static void Aerror(const res_state, FILE *, const char *, int, |
203 | const struct sockaddr *); |
204 | static void Perror(const res_state, FILE *, const char *, int); |
205 | #endif |
206 | static int sock_eq(struct sockaddr_in6 *, struct sockaddr_in6 *); |
207 | |
208 | /* Public. */ |
209 | |
210 | /* int |
211 | * res_isourserver(ina) |
212 | * looks up "ina" in _res.ns_addr_list[] |
213 | * returns: |
214 | * 0 : not found |
215 | * >0 : found |
216 | * author: |
217 | * paul vixie, 29may94 |
218 | */ |
219 | int |
220 | res_ourserver_p(const res_state statp, const struct sockaddr_in6 *inp) |
221 | { |
222 | int ns; |
223 | |
224 | if (inp->sin6_family == AF_INET) { |
225 | struct sockaddr_in *in4p = (struct sockaddr_in *) inp; |
226 | in_port_t port = in4p->sin_port; |
227 | in_addr_t addr = in4p->sin_addr.s_addr; |
228 | |
229 | for (ns = 0; ns < statp->nscount; ns++) { |
230 | const struct sockaddr_in *srv = |
231 | (struct sockaddr_in *) get_nsaddr (statp, ns); |
232 | |
233 | if ((srv->sin_family == AF_INET) && |
234 | (srv->sin_port == port) && |
235 | (srv->sin_addr.s_addr == INADDR_ANY || |
236 | srv->sin_addr.s_addr == addr)) |
237 | return (1); |
238 | } |
239 | } else if (inp->sin6_family == AF_INET6) { |
240 | for (ns = 0; ns < statp->nscount; ns++) { |
241 | const struct sockaddr_in6 *srv |
242 | = (struct sockaddr_in6 *) get_nsaddr (statp, ns); |
243 | if ((srv->sin6_family == AF_INET6) && |
244 | (srv->sin6_port == inp->sin6_port) && |
245 | !(memcmp(&srv->sin6_addr, &in6addr_any, |
246 | sizeof (struct in6_addr)) && |
247 | memcmp(&srv->sin6_addr, &inp->sin6_addr, |
248 | sizeof (struct in6_addr)))) |
249 | return (1); |
250 | } |
251 | } |
252 | return (0); |
253 | } |
254 | |
255 | /* int |
256 | * res_nameinquery(name, type, class, buf, eom) |
257 | * look for (name,type,class) in the query section of packet (buf,eom) |
258 | * requires: |
259 | * buf + HFIXEDSZ <= eom |
260 | * returns: |
261 | * -1 : format error |
262 | * 0 : not found |
263 | * >0 : found |
264 | * author: |
265 | * paul vixie, 29may94 |
266 | */ |
267 | int |
268 | res_nameinquery(const char *name, int type, int class, |
269 | const u_char *buf, const u_char *eom) |
270 | { |
271 | const u_char *cp = buf + HFIXEDSZ; |
272 | int qdcount = ntohs(((HEADER*)buf)->qdcount); |
273 | |
274 | while (qdcount-- > 0) { |
275 | char tname[MAXDNAME+1]; |
276 | int n, ttype, tclass; |
277 | |
278 | n = dn_expand(buf, eom, cp, tname, sizeof tname); |
279 | if (n < 0) |
280 | return (-1); |
281 | cp += n; |
282 | if (cp + 2 * INT16SZ > eom) |
283 | return (-1); |
284 | NS_GET16(ttype, cp); |
285 | NS_GET16(tclass, cp); |
286 | if (ttype == type && tclass == class && |
287 | ns_samename(tname, name) == 1) |
288 | return (1); |
289 | } |
290 | return (0); |
291 | } |
292 | libresolv_hidden_def (res_nameinquery) |
293 | |
294 | /* int |
295 | * res_queriesmatch(buf1, eom1, buf2, eom2) |
296 | * is there a 1:1 mapping of (name,type,class) |
297 | * in (buf1,eom1) and (buf2,eom2)? |
298 | * returns: |
299 | * -1 : format error |
300 | * 0 : not a 1:1 mapping |
301 | * >0 : is a 1:1 mapping |
302 | * author: |
303 | * paul vixie, 29may94 |
304 | */ |
305 | int |
306 | res_queriesmatch(const u_char *buf1, const u_char *eom1, |
307 | const u_char *buf2, const u_char *eom2) |
308 | { |
309 | if (buf1 + HFIXEDSZ > eom1 || buf2 + HFIXEDSZ > eom2) |
310 | return (-1); |
311 | |
312 | /* |
313 | * Only header section present in replies to |
314 | * dynamic update packets. |
315 | */ |
316 | if ((((HEADER *)buf1)->opcode == ns_o_update) && |
317 | (((HEADER *)buf2)->opcode == ns_o_update)) |
318 | return (1); |
319 | |
320 | /* Note that we initially do not convert QDCOUNT to the host byte |
321 | order. We can compare it with the second buffer's QDCOUNT |
322 | value without doing this. */ |
323 | int qdcount = ((HEADER*)buf1)->qdcount; |
324 | if (qdcount != ((HEADER*)buf2)->qdcount) |
325 | return (0); |
326 | |
327 | qdcount = htons (qdcount); |
328 | const u_char *cp = buf1 + HFIXEDSZ; |
329 | |
330 | while (qdcount-- > 0) { |
331 | char tname[MAXDNAME+1]; |
332 | int n, ttype, tclass; |
333 | |
334 | n = dn_expand(buf1, eom1, cp, tname, sizeof tname); |
335 | if (n < 0) |
336 | return (-1); |
337 | cp += n; |
338 | if (cp + 2 * INT16SZ > eom1) |
339 | return (-1); |
340 | NS_GET16(ttype, cp); |
341 | NS_GET16(tclass, cp); |
342 | if (!res_nameinquery(tname, ttype, tclass, buf2, eom2)) |
343 | return (0); |
344 | } |
345 | return (1); |
346 | } |
347 | libresolv_hidden_def (res_queriesmatch) |
348 | |
349 | int |
350 | __libc_res_nsend(res_state statp, const u_char *buf, int buflen, |
351 | const u_char *buf2, int buflen2, |
352 | u_char *ans, int anssiz, u_char **ansp, u_char **ansp2, |
353 | int *nansp2, int *resplen2, int *ansp2_malloced) |
354 | { |
355 | int gotsomewhere, terrno, try, v_circuit, resplen, ns, n; |
356 | |
357 | if (statp->nscount == 0) { |
358 | __set_errno (ESRCH); |
359 | return (-1); |
360 | } |
361 | |
362 | if (anssiz < (buf2 == NULL ? 1 : 2) * HFIXEDSZ) { |
363 | __set_errno (EINVAL); |
364 | return (-1); |
365 | } |
366 | |
367 | DprintQ((statp->options & RES_DEBUG) || (statp->pfcode & RES_PRF_QUERY), |
368 | (stdout, ";; res_send()\n" ), buf, buflen); |
369 | v_circuit = ((statp->options & RES_USEVC) |
370 | || buflen > PACKETSZ |
371 | || buflen2 > PACKETSZ); |
372 | gotsomewhere = 0; |
373 | terrno = ETIMEDOUT; |
374 | |
375 | /* |
376 | * If the ns_addr_list in the resolver context has changed, then |
377 | * invalidate our cached copy and the associated timing data. |
378 | */ |
379 | if (EXT(statp).nscount != 0) { |
380 | int needclose = 0; |
381 | |
382 | if (EXT(statp).nscount != statp->nscount) |
383 | needclose++; |
384 | else |
385 | for (ns = 0; ns < statp->nscount; ns++) { |
386 | if (statp->nsaddr_list[ns].sin_family != 0 |
387 | && !sock_eq((struct sockaddr_in6 *) |
388 | &statp->nsaddr_list[ns], |
389 | EXT(statp).nsaddrs[ns])) |
390 | { |
391 | needclose++; |
392 | break; |
393 | } |
394 | } |
395 | if (needclose) { |
396 | __res_iclose(statp, false); |
397 | EXT(statp).nscount = 0; |
398 | } |
399 | } |
400 | |
401 | /* |
402 | * Maybe initialize our private copy of the ns_addr_list. |
403 | */ |
404 | if (EXT(statp).nscount == 0) { |
405 | for (ns = 0; ns < statp->nscount; ns++) { |
406 | EXT(statp).nssocks[ns] = -1; |
407 | if (statp->nsaddr_list[ns].sin_family == 0) |
408 | continue; |
409 | if (EXT(statp).nsaddrs[ns] == NULL) |
410 | EXT(statp).nsaddrs[ns] = |
411 | malloc(sizeof (struct sockaddr_in6)); |
412 | if (EXT(statp).nsaddrs[ns] != NULL) |
413 | memset (mempcpy(EXT(statp).nsaddrs[ns], |
414 | &statp->nsaddr_list[ns], |
415 | sizeof (struct sockaddr_in)), |
416 | '\0', |
417 | sizeof (struct sockaddr_in6) |
418 | - sizeof (struct sockaddr_in)); |
419 | } |
420 | EXT(statp).nscount = statp->nscount; |
421 | } |
422 | |
423 | /* |
424 | * Some resolvers want to even out the load on their nameservers. |
425 | * Note that RES_BLAST overrides RES_ROTATE. |
426 | */ |
427 | if (__builtin_expect ((statp->options & RES_ROTATE) != 0, 0)) { |
428 | struct sockaddr_in ina; |
429 | struct sockaddr_in6 *inp; |
430 | int lastns = statp->nscount - 1; |
431 | int fd; |
432 | |
433 | inp = EXT(statp).nsaddrs[0]; |
434 | ina = statp->nsaddr_list[0]; |
435 | fd = EXT(statp).nssocks[0]; |
436 | for (ns = 0; ns < lastns; ns++) { |
437 | EXT(statp).nsaddrs[ns] = EXT(statp).nsaddrs[ns + 1]; |
438 | statp->nsaddr_list[ns] = statp->nsaddr_list[ns + 1]; |
439 | EXT(statp).nssocks[ns] = EXT(statp).nssocks[ns + 1]; |
440 | } |
441 | EXT(statp).nsaddrs[lastns] = inp; |
442 | statp->nsaddr_list[lastns] = ina; |
443 | EXT(statp).nssocks[lastns] = fd; |
444 | } |
445 | |
446 | /* |
447 | * Send request, RETRY times, or until successful. |
448 | */ |
449 | for (try = 0; try < statp->retry; try++) { |
450 | for (ns = 0; ns < statp->nscount; ns++) |
451 | { |
452 | #ifdef DEBUG |
453 | char tmpbuf[40]; |
454 | struct sockaddr *nsap = get_nsaddr (statp, ns); |
455 | #endif |
456 | |
457 | same_ns: |
458 | Dprint(statp->options & RES_DEBUG, |
459 | (stdout, ";; Querying server (# %d) address = %s\n" , |
460 | ns + 1, inet_ntop(nsap->sa_family, |
461 | (nsap->sa_family == AF_INET6 |
462 | ? (void *) &((struct sockaddr_in6 *) nsap)->sin6_addr |
463 | : (void *) &((struct sockaddr_in *) nsap)->sin_addr), |
464 | tmpbuf, sizeof (tmpbuf)))); |
465 | |
466 | if (__glibc_unlikely (v_circuit)) { |
467 | /* Use VC; at most one attempt per server. */ |
468 | try = statp->retry; |
469 | n = send_vc(statp, buf, buflen, buf2, buflen2, |
470 | &ans, &anssiz, &terrno, |
471 | ns, ansp, ansp2, nansp2, resplen2, |
472 | ansp2_malloced); |
473 | if (n < 0) |
474 | return (-1); |
475 | if (n == 0 && (buf2 == NULL || *resplen2 == 0)) |
476 | goto next_ns; |
477 | } else { |
478 | /* Use datagrams. */ |
479 | n = send_dg(statp, buf, buflen, buf2, buflen2, |
480 | &ans, &anssiz, &terrno, |
481 | ns, &v_circuit, &gotsomewhere, ansp, |
482 | ansp2, nansp2, resplen2, ansp2_malloced); |
483 | if (n < 0) |
484 | return (-1); |
485 | if (n == 0 && (buf2 == NULL || *resplen2 == 0)) |
486 | goto next_ns; |
487 | if (v_circuit) |
488 | // XXX Check whether both requests failed or |
489 | // XXX whether one has been answered successfully |
490 | goto same_ns; |
491 | } |
492 | |
493 | resplen = n; |
494 | |
495 | Dprint((statp->options & RES_DEBUG) || |
496 | ((statp->pfcode & RES_PRF_REPLY) && |
497 | (statp->pfcode & RES_PRF_HEAD1)), |
498 | (stdout, ";; got answer:\n" )); |
499 | |
500 | DprintQ((statp->options & RES_DEBUG) || |
501 | (statp->pfcode & RES_PRF_REPLY), |
502 | (stdout, "%s" , "" ), |
503 | ans, (resplen > anssiz) ? anssiz : resplen); |
504 | if (buf2 != NULL) { |
505 | DprintQ((statp->options & RES_DEBUG) || |
506 | (statp->pfcode & RES_PRF_REPLY), |
507 | (stdout, "%s" , "" ), |
508 | *ansp2, (*resplen2 > *nansp2) ? *nansp2 : *resplen2); |
509 | } |
510 | |
511 | /* |
512 | * If we have temporarily opened a virtual circuit, |
513 | * or if we haven't been asked to keep a socket open, |
514 | * close the socket. |
515 | */ |
516 | if ((v_circuit && (statp->options & RES_USEVC) == 0) || |
517 | (statp->options & RES_STAYOPEN) == 0) { |
518 | __res_iclose(statp, false); |
519 | } |
520 | return (resplen); |
521 | next_ns: ; |
522 | } /*foreach ns*/ |
523 | } /*foreach retry*/ |
524 | __res_iclose(statp, false); |
525 | if (!v_circuit) { |
526 | if (!gotsomewhere) |
527 | __set_errno (ECONNREFUSED); /* no nameservers found */ |
528 | else |
529 | __set_errno (ETIMEDOUT); /* no answer obtained */ |
530 | } else |
531 | __set_errno (terrno); |
532 | return (-1); |
533 | } |
534 | |
535 | int |
536 | res_nsend(res_state statp, |
537 | const u_char *buf, int buflen, u_char *ans, int anssiz) |
538 | { |
539 | return __libc_res_nsend(statp, buf, buflen, NULL, 0, ans, anssiz, |
540 | NULL, NULL, NULL, NULL, NULL); |
541 | } |
542 | libresolv_hidden_def (res_nsend) |
543 | |
544 | /* Private */ |
545 | |
546 | static struct sockaddr * |
547 | get_nsaddr (res_state statp, int n) |
548 | { |
549 | |
550 | if (statp->nsaddr_list[n].sin_family == 0 && EXT(statp).nsaddrs[n] != NULL) |
551 | /* EXT(statp).nsaddrs[n] holds an address that is larger than |
552 | struct sockaddr, and user code did not update |
553 | statp->nsaddr_list[n]. */ |
554 | return (struct sockaddr *) EXT(statp).nsaddrs[n]; |
555 | else |
556 | /* User code updated statp->nsaddr_list[n], or statp->nsaddr_list[n] |
557 | has the same content as EXT(statp).nsaddrs[n]. */ |
558 | return (struct sockaddr *) (void *) &statp->nsaddr_list[n]; |
559 | } |
560 | |
561 | /* Close the resolver structure, assign zero to *RESPLEN2 if RESPLEN2 |
562 | is not NULL, and return zero. */ |
563 | static int |
564 | __attribute__ ((warn_unused_result)) |
565 | close_and_return_error (res_state statp, int *resplen2) |
566 | { |
567 | __res_iclose(statp, false); |
568 | if (resplen2 != NULL) |
569 | *resplen2 = 0; |
570 | return 0; |
571 | } |
572 | |
573 | /* The send_vc function is responsible for sending a DNS query over TCP |
574 | to the nameserver numbered NS from the res_state STATP i.e. |
575 | EXT(statp).nssocks[ns]. The function supports sending both IPv4 and |
576 | IPv6 queries at the same serially on the same socket. |
577 | |
578 | Please note that for TCP there is no way to disable sending both |
579 | queries, unlike UDP, which honours RES_SNGLKUP and RES_SNGLKUPREOP |
580 | and sends the queries serially and waits for the result after each |
581 | sent query. This implementation should be corrected to honour these |
582 | options. |
583 | |
584 | Please also note that for TCP we send both queries over the same |
585 | socket one after another. This technically violates best practice |
586 | since the server is allowed to read the first query, respond, and |
587 | then close the socket (to service another client). If the server |
588 | does this, then the remaining second query in the socket data buffer |
589 | will cause the server to send the client an RST which will arrive |
590 | asynchronously and the client's OS will likely tear down the socket |
591 | receive buffer resulting in a potentially short read and lost |
592 | response data. This will force the client to retry the query again, |
593 | and this process may repeat until all servers and connection resets |
594 | are exhausted and then the query will fail. It's not known if this |
595 | happens with any frequency in real DNS server implementations. This |
596 | implementation should be corrected to use two sockets by default for |
597 | parallel queries. |
598 | |
599 | The query stored in BUF of BUFLEN length is sent first followed by |
600 | the query stored in BUF2 of BUFLEN2 length. Queries are sent |
601 | serially on the same socket. |
602 | |
603 | Answers to the query are stored firstly in *ANSP up to a max of |
604 | *ANSSIZP bytes. If more than *ANSSIZP bytes are needed and ANSCP |
605 | is non-NULL (to indicate that modifying the answer buffer is allowed) |
606 | then malloc is used to allocate a new response buffer and ANSCP and |
607 | ANSP will both point to the new buffer. If more than *ANSSIZP bytes |
608 | are needed but ANSCP is NULL, then as much of the response as |
609 | possible is read into the buffer, but the results will be truncated. |
610 | When truncation happens because of a small answer buffer the DNS |
611 | packets header field TC will bet set to 1, indicating a truncated |
612 | message and the rest of the socket data will be read and discarded. |
613 | |
614 | Answers to the query are stored secondly in *ANSP2 up to a max of |
615 | *ANSSIZP2 bytes, with the actual response length stored in |
616 | *RESPLEN2. If more than *ANSSIZP bytes are needed and ANSP2 |
617 | is non-NULL (required for a second query) then malloc is used to |
618 | allocate a new response buffer, *ANSSIZP2 is set to the new buffer |
619 | size and *ANSP2_MALLOCED is set to 1. |
620 | |
621 | The ANSP2_MALLOCED argument will eventually be removed as the |
622 | change in buffer pointer can be used to detect the buffer has |
623 | changed and that the caller should use free on the new buffer. |
624 | |
625 | Note that the answers may arrive in any order from the server and |
626 | therefore the first and second answer buffers may not correspond to |
627 | the first and second queries. |
628 | |
629 | It is not supported to call this function with a non-NULL ANSP2 |
630 | but a NULL ANSCP. Put another way, you can call send_vc with a |
631 | single unmodifiable buffer or two modifiable buffers, but no other |
632 | combination is supported. |
633 | |
634 | It is the caller's responsibility to free the malloc allocated |
635 | buffers by detecting that the pointers have changed from their |
636 | original values i.e. *ANSCP or *ANSP2 has changed. |
637 | |
638 | If errors are encountered then *TERRNO is set to an appropriate |
639 | errno value and a zero result is returned for a recoverable error, |
640 | and a less-than zero result is returned for a non-recoverable error. |
641 | |
642 | If no errors are encountered then *TERRNO is left unmodified and |
643 | a the length of the first response in bytes is returned. */ |
644 | static int |
645 | send_vc(res_state statp, |
646 | const u_char *buf, int buflen, const u_char *buf2, int buflen2, |
647 | u_char **ansp, int *anssizp, |
648 | int *terrno, int ns, u_char **anscp, u_char **ansp2, int *anssizp2, |
649 | int *resplen2, int *ansp2_malloced) |
650 | { |
651 | const HEADER *hp = (HEADER *) buf; |
652 | const HEADER *hp2 = (HEADER *) buf2; |
653 | HEADER *anhp = (HEADER *) *ansp; |
654 | struct sockaddr *nsap = get_nsaddr (statp, ns); |
655 | int truncating, connreset, n; |
656 | /* On some architectures compiler might emit a warning indicating |
657 | 'resplen' may be used uninitialized. However if buf2 == NULL |
658 | then this code won't be executed; if buf2 != NULL, then first |
659 | time round the loop recvresp1 and recvresp2 will be 0 so this |
660 | code won't be executed but "thisresplenp = &resplen;" followed |
661 | by "*thisresplenp = rlen;" will be executed so that subsequent |
662 | times round the loop resplen has been initialized. So this is |
663 | a false-positive. |
664 | */ |
665 | DIAG_PUSH_NEEDS_COMMENT; |
666 | DIAG_IGNORE_NEEDS_COMMENT (5, "-Wmaybe-uninitialized" ); |
667 | int resplen; |
668 | DIAG_POP_NEEDS_COMMENT; |
669 | struct iovec iov[4]; |
670 | u_short len; |
671 | u_short len2; |
672 | u_char *cp; |
673 | |
674 | connreset = 0; |
675 | same_ns: |
676 | truncating = 0; |
677 | |
678 | /* Are we still talking to whom we want to talk to? */ |
679 | if (statp->_vcsock >= 0 && (statp->_flags & RES_F_VC) != 0) { |
680 | struct sockaddr_in6 peer; |
681 | socklen_t size = sizeof peer; |
682 | |
683 | if (getpeername(statp->_vcsock, |
684 | (struct sockaddr *)&peer, &size) < 0 || |
685 | !sock_eq(&peer, (struct sockaddr_in6 *) nsap)) { |
686 | __res_iclose(statp, false); |
687 | statp->_flags &= ~RES_F_VC; |
688 | } |
689 | } |
690 | |
691 | if (statp->_vcsock < 0 || (statp->_flags & RES_F_VC) == 0) { |
692 | if (statp->_vcsock >= 0) |
693 | __res_iclose(statp, false); |
694 | |
695 | statp->_vcsock = socket(nsap->sa_family, SOCK_STREAM, 0); |
696 | if (statp->_vcsock < 0) { |
697 | *terrno = errno; |
698 | Perror(statp, stderr, "socket(vc)" , errno); |
699 | if (resplen2 != NULL) |
700 | *resplen2 = 0; |
701 | return (-1); |
702 | } |
703 | __set_errno (0); |
704 | if (connect(statp->_vcsock, nsap, |
705 | nsap->sa_family == AF_INET |
706 | ? sizeof (struct sockaddr_in) |
707 | : sizeof (struct sockaddr_in6)) < 0) { |
708 | *terrno = errno; |
709 | Aerror(statp, stderr, "connect/vc" , errno, nsap); |
710 | return close_and_return_error (statp, resplen2); |
711 | } |
712 | statp->_flags |= RES_F_VC; |
713 | } |
714 | |
715 | /* |
716 | * Send length & message |
717 | */ |
718 | len = htons ((u_short) buflen); |
719 | evConsIovec(&len, INT16SZ, &iov[0]); |
720 | evConsIovec((void*)buf, buflen, &iov[1]); |
721 | int niov = 2; |
722 | ssize_t explen = INT16SZ + buflen; |
723 | if (buf2 != NULL) { |
724 | len2 = htons ((u_short) buflen2); |
725 | evConsIovec(&len2, INT16SZ, &iov[2]); |
726 | evConsIovec((void*)buf2, buflen2, &iov[3]); |
727 | niov = 4; |
728 | explen += INT16SZ + buflen2; |
729 | } |
730 | if (TEMP_FAILURE_RETRY (writev(statp->_vcsock, iov, niov)) != explen) { |
731 | *terrno = errno; |
732 | Perror(statp, stderr, "write failed" , errno); |
733 | return close_and_return_error (statp, resplen2); |
734 | } |
735 | /* |
736 | * Receive length & response |
737 | */ |
738 | int recvresp1 = 0; |
739 | /* Skip the second response if there is no second query. |
740 | To do that we mark the second response as received. */ |
741 | int recvresp2 = buf2 == NULL; |
742 | uint16_t rlen16; |
743 | read_len: |
744 | cp = (u_char *)&rlen16; |
745 | len = sizeof(rlen16); |
746 | while ((n = TEMP_FAILURE_RETRY (read(statp->_vcsock, cp, |
747 | (int)len))) > 0) { |
748 | cp += n; |
749 | if ((len -= n) <= 0) |
750 | break; |
751 | } |
752 | if (n <= 0) { |
753 | *terrno = errno; |
754 | Perror(statp, stderr, "read failed" , errno); |
755 | /* |
756 | * A long running process might get its TCP |
757 | * connection reset if the remote server was |
758 | * restarted. Requery the server instead of |
759 | * trying a new one. When there is only one |
760 | * server, this means that a query might work |
761 | * instead of failing. We only allow one reset |
762 | * per query to prevent looping. |
763 | */ |
764 | if (*terrno == ECONNRESET && !connreset) |
765 | { |
766 | __res_iclose (statp, false); |
767 | connreset = 1; |
768 | goto same_ns; |
769 | } |
770 | return close_and_return_error (statp, resplen2); |
771 | } |
772 | int rlen = ntohs (rlen16); |
773 | |
774 | int *thisanssizp; |
775 | u_char **thisansp; |
776 | int *thisresplenp; |
777 | if ((recvresp1 | recvresp2) == 0 || buf2 == NULL) { |
778 | /* We have not received any responses |
779 | yet or we only have one response to |
780 | receive. */ |
781 | thisanssizp = anssizp; |
782 | thisansp = anscp ?: ansp; |
783 | assert (anscp != NULL || ansp2 == NULL); |
784 | thisresplenp = &resplen; |
785 | } else { |
786 | thisanssizp = anssizp2; |
787 | thisansp = ansp2; |
788 | thisresplenp = resplen2; |
789 | } |
790 | anhp = (HEADER *) *thisansp; |
791 | |
792 | *thisresplenp = rlen; |
793 | /* Is the answer buffer too small? */ |
794 | if (*thisanssizp < rlen) { |
795 | /* If the current buffer is not the the static |
796 | user-supplied buffer then we can reallocate |
797 | it. */ |
798 | if (thisansp != NULL && thisansp != ansp) { |
799 | /* Always allocate MAXPACKET, callers expect |
800 | this specific size. */ |
801 | u_char *newp = malloc (MAXPACKET); |
802 | if (newp == NULL) |
803 | { |
804 | *terrno = ENOMEM; |
805 | return close_and_return_error (statp, resplen2); |
806 | } |
807 | *thisanssizp = MAXPACKET; |
808 | *thisansp = newp; |
809 | if (thisansp == ansp2) |
810 | *ansp2_malloced = 1; |
811 | anhp = (HEADER *) newp; |
812 | /* A uint16_t can't be larger than MAXPACKET |
813 | thus it's safe to allocate MAXPACKET but |
814 | read RLEN bytes instead. */ |
815 | len = rlen; |
816 | } else { |
817 | Dprint(statp->options & RES_DEBUG, |
818 | (stdout, ";; response truncated\n" ) |
819 | ); |
820 | truncating = 1; |
821 | len = *thisanssizp; |
822 | } |
823 | } else |
824 | len = rlen; |
825 | |
826 | if (__glibc_unlikely (len < HFIXEDSZ)) { |
827 | /* |
828 | * Undersized message. |
829 | */ |
830 | Dprint(statp->options & RES_DEBUG, |
831 | (stdout, ";; undersized: %d\n" , len)); |
832 | *terrno = EMSGSIZE; |
833 | return close_and_return_error (statp, resplen2); |
834 | } |
835 | |
836 | cp = *thisansp; |
837 | while (len != 0 && (n = read(statp->_vcsock, (char *)cp, (int)len)) > 0){ |
838 | cp += n; |
839 | len -= n; |
840 | } |
841 | if (__glibc_unlikely (n <= 0)) { |
842 | *terrno = errno; |
843 | Perror(statp, stderr, "read(vc)" , errno); |
844 | return close_and_return_error (statp, resplen2); |
845 | } |
846 | if (__glibc_unlikely (truncating)) { |
847 | /* |
848 | * Flush rest of answer so connection stays in synch. |
849 | */ |
850 | anhp->tc = 1; |
851 | len = rlen - *thisanssizp; |
852 | while (len != 0) { |
853 | char junk[PACKETSZ]; |
854 | |
855 | n = read(statp->_vcsock, junk, |
856 | (len > sizeof junk) ? sizeof junk : len); |
857 | if (n > 0) |
858 | len -= n; |
859 | else |
860 | break; |
861 | } |
862 | } |
863 | /* |
864 | * If the calling application has bailed out of |
865 | * a previous call and failed to arrange to have |
866 | * the circuit closed or the server has got |
867 | * itself confused, then drop the packet and |
868 | * wait for the correct one. |
869 | */ |
870 | if ((recvresp1 || hp->id != anhp->id) |
871 | && (recvresp2 || hp2->id != anhp->id)) { |
872 | DprintQ((statp->options & RES_DEBUG) || |
873 | (statp->pfcode & RES_PRF_REPLY), |
874 | (stdout, ";; old answer (unexpected):\n" ), |
875 | *thisansp, |
876 | (rlen > *thisanssizp) ? *thisanssizp: rlen); |
877 | goto read_len; |
878 | } |
879 | |
880 | /* Mark which reply we received. */ |
881 | if (recvresp1 == 0 && hp->id == anhp->id) |
882 | recvresp1 = 1; |
883 | else |
884 | recvresp2 = 1; |
885 | /* Repeat waiting if we have a second answer to arrive. */ |
886 | if ((recvresp1 & recvresp2) == 0) |
887 | goto read_len; |
888 | |
889 | /* |
890 | * All is well, or the error is fatal. Signal that the |
891 | * next nameserver ought not be tried. |
892 | */ |
893 | return resplen; |
894 | } |
895 | |
896 | static int |
897 | reopen (res_state statp, int *terrno, int ns) |
898 | { |
899 | if (EXT(statp).nssocks[ns] == -1) { |
900 | struct sockaddr *nsap = get_nsaddr (statp, ns); |
901 | socklen_t slen; |
902 | |
903 | /* only try IPv6 if IPv6 NS and if not failed before */ |
904 | if (nsap->sa_family == AF_INET6 && !statp->ipv6_unavail) { |
905 | EXT(statp).nssocks[ns] |
906 | = socket(PF_INET6, SOCK_DGRAM|SOCK_NONBLOCK, 0); |
907 | if (EXT(statp).nssocks[ns] < 0) |
908 | statp->ipv6_unavail = errno == EAFNOSUPPORT; |
909 | slen = sizeof (struct sockaddr_in6); |
910 | } else if (nsap->sa_family == AF_INET) { |
911 | EXT(statp).nssocks[ns] |
912 | = socket(PF_INET, SOCK_DGRAM|SOCK_NONBLOCK, 0); |
913 | slen = sizeof (struct sockaddr_in); |
914 | } |
915 | if (EXT(statp).nssocks[ns] < 0) { |
916 | *terrno = errno; |
917 | Perror(statp, stderr, "socket(dg)" , errno); |
918 | return (-1); |
919 | } |
920 | |
921 | /* |
922 | * On a 4.3BSD+ machine (client and server, |
923 | * actually), sending to a nameserver datagram |
924 | * port with no nameserver will cause an |
925 | * ICMP port unreachable message to be returned. |
926 | * If our datagram socket is "connected" to the |
927 | * server, we get an ECONNREFUSED error on the next |
928 | * socket operation, and select returns if the |
929 | * error message is received. We can thus detect |
930 | * the absence of a nameserver without timing out. |
931 | */ |
932 | /* With GCC 5.3 when compiling with -Os the compiler |
933 | emits a warning that slen may be used uninitialized, |
934 | but that is never true. Both slen and |
935 | EXT(statp).nssocks[ns] are initialized together or |
936 | the function return -1 before control flow reaches |
937 | the call to connect with slen. */ |
938 | DIAG_PUSH_NEEDS_COMMENT; |
939 | DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized" ); |
940 | if (connect(EXT(statp).nssocks[ns], nsap, slen) < 0) { |
941 | DIAG_POP_NEEDS_COMMENT; |
942 | Aerror(statp, stderr, "connect(dg)" , errno, nsap); |
943 | __res_iclose(statp, false); |
944 | return (0); |
945 | } |
946 | } |
947 | |
948 | return 1; |
949 | } |
950 | |
951 | /* The send_dg function is responsible for sending a DNS query over UDP |
952 | to the nameserver numbered NS from the res_state STATP i.e. |
953 | EXT(statp).nssocks[ns]. The function supports IPv4 and IPv6 queries |
954 | along with the ability to send the query in parallel for both stacks |
955 | (default) or serially (RES_SINGLKUP). It also supports serial lookup |
956 | with a close and reopen of the socket used to talk to the server |
957 | (RES_SNGLKUPREOP) to work around broken name servers. |
958 | |
959 | The query stored in BUF of BUFLEN length is sent first followed by |
960 | the query stored in BUF2 of BUFLEN2 length. Queries are sent |
961 | in parallel (default) or serially (RES_SINGLKUP or RES_SNGLKUPREOP). |
962 | |
963 | Answers to the query are stored firstly in *ANSP up to a max of |
964 | *ANSSIZP bytes. If more than *ANSSIZP bytes are needed and ANSCP |
965 | is non-NULL (to indicate that modifying the answer buffer is allowed) |
966 | then malloc is used to allocate a new response buffer and ANSCP and |
967 | ANSP will both point to the new buffer. If more than *ANSSIZP bytes |
968 | are needed but ANSCP is NULL, then as much of the response as |
969 | possible is read into the buffer, but the results will be truncated. |
970 | When truncation happens because of a small answer buffer the DNS |
971 | packets header field TC will bet set to 1, indicating a truncated |
972 | message, while the rest of the UDP packet is discarded. |
973 | |
974 | Answers to the query are stored secondly in *ANSP2 up to a max of |
975 | *ANSSIZP2 bytes, with the actual response length stored in |
976 | *RESPLEN2. If more than *ANSSIZP bytes are needed and ANSP2 |
977 | is non-NULL (required for a second query) then malloc is used to |
978 | allocate a new response buffer, *ANSSIZP2 is set to the new buffer |
979 | size and *ANSP2_MALLOCED is set to 1. |
980 | |
981 | The ANSP2_MALLOCED argument will eventually be removed as the |
982 | change in buffer pointer can be used to detect the buffer has |
983 | changed and that the caller should use free on the new buffer. |
984 | |
985 | Note that the answers may arrive in any order from the server and |
986 | therefore the first and second answer buffers may not correspond to |
987 | the first and second queries. |
988 | |
989 | It is not supported to call this function with a non-NULL ANSP2 |
990 | but a NULL ANSCP. Put another way, you can call send_vc with a |
991 | single unmodifiable buffer or two modifiable buffers, but no other |
992 | combination is supported. |
993 | |
994 | It is the caller's responsibility to free the malloc allocated |
995 | buffers by detecting that the pointers have changed from their |
996 | original values i.e. *ANSCP or *ANSP2 has changed. |
997 | |
998 | If an answer is truncated because of UDP datagram DNS limits then |
999 | *V_CIRCUIT is set to 1 and the return value non-zero to indicate to |
1000 | the caller to retry with TCP. The value *GOTSOMEWHERE is set to 1 |
1001 | if any progress was made reading a response from the nameserver and |
1002 | is used by the caller to distinguish between ECONNREFUSED and |
1003 | ETIMEDOUT (the latter if *GOTSOMEWHERE is 1). |
1004 | |
1005 | If errors are encountered then *TERRNO is set to an appropriate |
1006 | errno value and a zero result is returned for a recoverable error, |
1007 | and a less-than zero result is returned for a non-recoverable error. |
1008 | |
1009 | If no errors are encountered then *TERRNO is left unmodified and |
1010 | a the length of the first response in bytes is returned. */ |
1011 | static int |
1012 | send_dg(res_state statp, |
1013 | const u_char *buf, int buflen, const u_char *buf2, int buflen2, |
1014 | u_char **ansp, int *anssizp, |
1015 | int *terrno, int ns, int *v_circuit, int *gotsomewhere, u_char **anscp, |
1016 | u_char **ansp2, int *anssizp2, int *resplen2, int *ansp2_malloced) |
1017 | { |
1018 | const HEADER *hp = (HEADER *) buf; |
1019 | const HEADER *hp2 = (HEADER *) buf2; |
1020 | struct timespec now, timeout, finish; |
1021 | struct pollfd pfd[1]; |
1022 | int ptimeout; |
1023 | struct sockaddr_in6 from; |
1024 | int resplen = 0; |
1025 | int n; |
1026 | |
1027 | /* |
1028 | * Compute time for the total operation. |
1029 | */ |
1030 | int seconds = (statp->retrans << ns); |
1031 | if (ns > 0) |
1032 | seconds /= statp->nscount; |
1033 | if (seconds <= 0) |
1034 | seconds = 1; |
1035 | bool single_request_reopen = (statp->options & RES_SNGLKUPREOP) != 0; |
1036 | bool single_request = (((statp->options & RES_SNGLKUP) != 0) |
1037 | | single_request_reopen); |
1038 | int save_gotsomewhere = *gotsomewhere; |
1039 | |
1040 | int retval; |
1041 | retry_reopen: |
1042 | retval = reopen (statp, terrno, ns); |
1043 | if (retval <= 0) |
1044 | { |
1045 | if (resplen2 != NULL) |
1046 | *resplen2 = 0; |
1047 | return retval; |
1048 | } |
1049 | retry: |
1050 | evNowTime(&now); |
1051 | evConsTime(&timeout, seconds, 0); |
1052 | evAddTime(&finish, &now, &timeout); |
1053 | int need_recompute = 0; |
1054 | int nwritten = 0; |
1055 | int recvresp1 = 0; |
1056 | /* Skip the second response if there is no second query. |
1057 | To do that we mark the second response as received. */ |
1058 | int recvresp2 = buf2 == NULL; |
1059 | pfd[0].fd = EXT(statp).nssocks[ns]; |
1060 | pfd[0].events = POLLOUT; |
1061 | wait: |
1062 | if (need_recompute) { |
1063 | recompute_resend: |
1064 | evNowTime(&now); |
1065 | if (evCmpTime(finish, now) <= 0) { |
1066 | poll_err_out: |
1067 | Perror(statp, stderr, "poll" , errno); |
1068 | return close_and_return_error (statp, resplen2); |
1069 | } |
1070 | evSubTime(&timeout, &finish, &now); |
1071 | need_recompute = 0; |
1072 | } |
1073 | /* Convert struct timespec in milliseconds. */ |
1074 | ptimeout = timeout.tv_sec * 1000 + timeout.tv_nsec / 1000000; |
1075 | |
1076 | n = 0; |
1077 | if (nwritten == 0) |
1078 | n = __poll (pfd, 1, 0); |
1079 | if (__glibc_unlikely (n == 0)) { |
1080 | n = __poll (pfd, 1, ptimeout); |
1081 | need_recompute = 1; |
1082 | } |
1083 | if (n == 0) { |
1084 | Dprint(statp->options & RES_DEBUG, (stdout, ";; timeout\n" )); |
1085 | if (resplen > 1 && (recvresp1 || (buf2 != NULL && recvresp2))) |
1086 | { |
1087 | /* There are quite a few broken name servers out |
1088 | there which don't handle two outstanding |
1089 | requests from the same source. There are also |
1090 | broken firewall settings. If we time out after |
1091 | having received one answer switch to the mode |
1092 | where we send the second request only once we |
1093 | have received the first answer. */ |
1094 | if (!single_request) |
1095 | { |
1096 | statp->options |= RES_SNGLKUP; |
1097 | single_request = true; |
1098 | *gotsomewhere = save_gotsomewhere; |
1099 | goto retry; |
1100 | } |
1101 | else if (!single_request_reopen) |
1102 | { |
1103 | statp->options |= RES_SNGLKUPREOP; |
1104 | single_request_reopen = true; |
1105 | *gotsomewhere = save_gotsomewhere; |
1106 | __res_iclose (statp, false); |
1107 | goto retry_reopen; |
1108 | } |
1109 | |
1110 | *resplen2 = 1; |
1111 | return resplen; |
1112 | } |
1113 | |
1114 | *gotsomewhere = 1; |
1115 | if (resplen2 != NULL) |
1116 | *resplen2 = 0; |
1117 | return 0; |
1118 | } |
1119 | if (n < 0) { |
1120 | if (errno == EINTR) |
1121 | goto recompute_resend; |
1122 | |
1123 | goto poll_err_out; |
1124 | } |
1125 | __set_errno (0); |
1126 | if (pfd[0].revents & POLLOUT) { |
1127 | #ifndef __ASSUME_SENDMMSG |
1128 | static int have_sendmmsg; |
1129 | #else |
1130 | # define have_sendmmsg 1 |
1131 | #endif |
1132 | if (have_sendmmsg >= 0 && nwritten == 0 && buf2 != NULL |
1133 | && !single_request) |
1134 | { |
1135 | struct iovec iov[2]; |
1136 | struct mmsghdr reqs[2]; |
1137 | reqs[0].msg_hdr.msg_name = NULL; |
1138 | reqs[0].msg_hdr.msg_namelen = 0; |
1139 | reqs[0].msg_hdr.msg_iov = &iov[0]; |
1140 | reqs[0].msg_hdr.msg_iovlen = 1; |
1141 | iov[0].iov_base = (void *) buf; |
1142 | iov[0].iov_len = buflen; |
1143 | reqs[0].msg_hdr.msg_control = NULL; |
1144 | reqs[0].msg_hdr.msg_controllen = 0; |
1145 | |
1146 | reqs[1].msg_hdr.msg_name = NULL; |
1147 | reqs[1].msg_hdr.msg_namelen = 0; |
1148 | reqs[1].msg_hdr.msg_iov = &iov[1]; |
1149 | reqs[1].msg_hdr.msg_iovlen = 1; |
1150 | iov[1].iov_base = (void *) buf2; |
1151 | iov[1].iov_len = buflen2; |
1152 | reqs[1].msg_hdr.msg_control = NULL; |
1153 | reqs[1].msg_hdr.msg_controllen = 0; |
1154 | |
1155 | int ndg = __sendmmsg (pfd[0].fd, reqs, 2, MSG_NOSIGNAL); |
1156 | if (__glibc_likely (ndg == 2)) |
1157 | { |
1158 | if (reqs[0].msg_len != buflen |
1159 | || reqs[1].msg_len != buflen2) |
1160 | goto fail_sendmmsg; |
1161 | |
1162 | pfd[0].events = POLLIN; |
1163 | nwritten += 2; |
1164 | } |
1165 | else if (ndg == 1 && reqs[0].msg_len == buflen) |
1166 | goto just_one; |
1167 | else if (ndg < 0 && (errno == EINTR || errno == EAGAIN)) |
1168 | goto recompute_resend; |
1169 | else |
1170 | { |
1171 | #ifndef __ASSUME_SENDMMSG |
1172 | if (__glibc_unlikely (have_sendmmsg == 0)) |
1173 | { |
1174 | if (ndg < 0 && errno == ENOSYS) |
1175 | { |
1176 | have_sendmmsg = -1; |
1177 | goto try_send; |
1178 | } |
1179 | have_sendmmsg = 1; |
1180 | } |
1181 | #endif |
1182 | |
1183 | fail_sendmmsg: |
1184 | Perror(statp, stderr, "sendmmsg" , errno); |
1185 | return close_and_return_error (statp, resplen2); |
1186 | } |
1187 | } |
1188 | else |
1189 | { |
1190 | ssize_t sr; |
1191 | #ifndef __ASSUME_SENDMMSG |
1192 | try_send: |
1193 | #endif |
1194 | if (nwritten != 0) |
1195 | sr = send (pfd[0].fd, buf2, buflen2, MSG_NOSIGNAL); |
1196 | else |
1197 | sr = send (pfd[0].fd, buf, buflen, MSG_NOSIGNAL); |
1198 | |
1199 | if (sr != (nwritten != 0 ? buflen2 : buflen)) { |
1200 | if (errno == EINTR || errno == EAGAIN) |
1201 | goto recompute_resend; |
1202 | Perror(statp, stderr, "send" , errno); |
1203 | return close_and_return_error (statp, resplen2); |
1204 | } |
1205 | just_one: |
1206 | if (nwritten != 0 || buf2 == NULL || single_request) |
1207 | pfd[0].events = POLLIN; |
1208 | else |
1209 | pfd[0].events = POLLIN | POLLOUT; |
1210 | ++nwritten; |
1211 | } |
1212 | goto wait; |
1213 | } else if (pfd[0].revents & POLLIN) { |
1214 | int *thisanssizp; |
1215 | u_char **thisansp; |
1216 | int *thisresplenp; |
1217 | |
1218 | if ((recvresp1 | recvresp2) == 0 || buf2 == NULL) { |
1219 | /* We have not received any responses |
1220 | yet or we only have one response to |
1221 | receive. */ |
1222 | thisanssizp = anssizp; |
1223 | thisansp = anscp ?: ansp; |
1224 | assert (anscp != NULL || ansp2 == NULL); |
1225 | thisresplenp = &resplen; |
1226 | } else { |
1227 | thisanssizp = anssizp2; |
1228 | thisansp = ansp2; |
1229 | thisresplenp = resplen2; |
1230 | } |
1231 | |
1232 | if (*thisanssizp < MAXPACKET |
1233 | /* If the current buffer is not the the static |
1234 | user-supplied buffer then we can reallocate |
1235 | it. */ |
1236 | && (thisansp != NULL && thisansp != ansp) |
1237 | #ifdef FIONREAD |
1238 | /* Is the size too small? */ |
1239 | && (ioctl (pfd[0].fd, FIONREAD, thisresplenp) < 0 |
1240 | || *thisanssizp < *thisresplenp) |
1241 | #endif |
1242 | ) { |
1243 | /* Always allocate MAXPACKET, callers expect |
1244 | this specific size. */ |
1245 | u_char *newp = malloc (MAXPACKET); |
1246 | if (newp != NULL) { |
1247 | *thisanssizp = MAXPACKET; |
1248 | *thisansp = newp; |
1249 | if (thisansp == ansp2) |
1250 | *ansp2_malloced = 1; |
1251 | } |
1252 | } |
1253 | /* We could end up with truncation if anscp was NULL |
1254 | (not allowed to change caller's buffer) and the |
1255 | response buffer size is too small. This isn't a |
1256 | reliable way to detect truncation because the ioctl |
1257 | may be an inaccurate report of the UDP message size. |
1258 | Therefore we use this only to issue debug output. |
1259 | To do truncation accurately with UDP we need |
1260 | MSG_TRUNC which is only available on Linux. We |
1261 | can abstract out the Linux-specific feature in the |
1262 | future to detect truncation. */ |
1263 | if (__glibc_unlikely (*thisanssizp < *thisresplenp)) { |
1264 | Dprint(statp->options & RES_DEBUG, |
1265 | (stdout, ";; response may be truncated (UDP)\n" ) |
1266 | ); |
1267 | } |
1268 | |
1269 | HEADER *anhp = (HEADER *) *thisansp; |
1270 | socklen_t fromlen = sizeof(struct sockaddr_in6); |
1271 | assert (sizeof(from) <= fromlen); |
1272 | *thisresplenp = recvfrom(pfd[0].fd, (char*)*thisansp, |
1273 | *thisanssizp, 0, |
1274 | (struct sockaddr *)&from, &fromlen); |
1275 | if (__glibc_unlikely (*thisresplenp <= 0)) { |
1276 | if (errno == EINTR || errno == EAGAIN) { |
1277 | need_recompute = 1; |
1278 | goto wait; |
1279 | } |
1280 | Perror(statp, stderr, "recvfrom" , errno); |
1281 | return close_and_return_error (statp, resplen2); |
1282 | } |
1283 | *gotsomewhere = 1; |
1284 | if (__glibc_unlikely (*thisresplenp < HFIXEDSZ)) { |
1285 | /* |
1286 | * Undersized message. |
1287 | */ |
1288 | Dprint(statp->options & RES_DEBUG, |
1289 | (stdout, ";; undersized: %d\n" , |
1290 | *thisresplenp)); |
1291 | *terrno = EMSGSIZE; |
1292 | return close_and_return_error (statp, resplen2); |
1293 | } |
1294 | if ((recvresp1 || hp->id != anhp->id) |
1295 | && (recvresp2 || hp2->id != anhp->id)) { |
1296 | /* |
1297 | * response from old query, ignore it. |
1298 | * XXX - potential security hazard could |
1299 | * be detected here. |
1300 | */ |
1301 | DprintQ((statp->options & RES_DEBUG) || |
1302 | (statp->pfcode & RES_PRF_REPLY), |
1303 | (stdout, ";; old answer:\n" ), |
1304 | *thisansp, |
1305 | (*thisresplenp > *thisanssizp) |
1306 | ? *thisanssizp : *thisresplenp); |
1307 | goto wait; |
1308 | } |
1309 | if (!(statp->options & RES_INSECURE1) && |
1310 | !res_ourserver_p(statp, &from)) { |
1311 | /* |
1312 | * response from wrong server? ignore it. |
1313 | * XXX - potential security hazard could |
1314 | * be detected here. |
1315 | */ |
1316 | DprintQ((statp->options & RES_DEBUG) || |
1317 | (statp->pfcode & RES_PRF_REPLY), |
1318 | (stdout, ";; not our server:\n" ), |
1319 | *thisansp, |
1320 | (*thisresplenp > *thisanssizp) |
1321 | ? *thisanssizp : *thisresplenp); |
1322 | goto wait; |
1323 | } |
1324 | #ifdef RES_USE_EDNS0 |
1325 | if (anhp->rcode == FORMERR |
1326 | && (statp->options & RES_USE_EDNS0) != 0U) { |
1327 | /* |
1328 | * Do not retry if the server does not understand |
1329 | * EDNS0. The case has to be captured here, as |
1330 | * FORMERR packet do not carry query section, hence |
1331 | * res_queriesmatch() returns 0. |
1332 | */ |
1333 | DprintQ(statp->options & RES_DEBUG, |
1334 | (stdout, |
1335 | "server rejected query with EDNS0:\n" ), |
1336 | *thisansp, |
1337 | (*thisresplenp > *thisanssizp) |
1338 | ? *thisanssizp : *thisresplenp); |
1339 | /* record the error */ |
1340 | statp->_flags |= RES_F_EDNS0ERR; |
1341 | return close_and_return_error (statp, resplen2); |
1342 | } |
1343 | #endif |
1344 | if (!(statp->options & RES_INSECURE2) |
1345 | && (recvresp1 || !res_queriesmatch(buf, buf + buflen, |
1346 | *thisansp, |
1347 | *thisansp |
1348 | + *thisanssizp)) |
1349 | && (recvresp2 || !res_queriesmatch(buf2, buf2 + buflen2, |
1350 | *thisansp, |
1351 | *thisansp |
1352 | + *thisanssizp))) { |
1353 | /* |
1354 | * response contains wrong query? ignore it. |
1355 | * XXX - potential security hazard could |
1356 | * be detected here. |
1357 | */ |
1358 | DprintQ((statp->options & RES_DEBUG) || |
1359 | (statp->pfcode & RES_PRF_REPLY), |
1360 | (stdout, ";; wrong query name:\n" ), |
1361 | *thisansp, |
1362 | (*thisresplenp > *thisanssizp) |
1363 | ? *thisanssizp : *thisresplenp); |
1364 | goto wait; |
1365 | } |
1366 | if (anhp->rcode == SERVFAIL || |
1367 | anhp->rcode == NOTIMP || |
1368 | anhp->rcode == REFUSED) { |
1369 | DprintQ(statp->options & RES_DEBUG, |
1370 | (stdout, "server rejected query:\n" ), |
1371 | *thisansp, |
1372 | (*thisresplenp > *thisanssizp) |
1373 | ? *thisanssizp : *thisresplenp); |
1374 | |
1375 | next_ns: |
1376 | if (recvresp1 || (buf2 != NULL && recvresp2)) { |
1377 | *resplen2 = 0; |
1378 | return resplen; |
1379 | } |
1380 | if (buf2 != NULL) |
1381 | { |
1382 | /* No data from the first reply. */ |
1383 | resplen = 0; |
1384 | /* We are waiting for a possible second reply. */ |
1385 | if (hp->id == anhp->id) |
1386 | recvresp1 = 1; |
1387 | else |
1388 | recvresp2 = 1; |
1389 | |
1390 | goto wait; |
1391 | } |
1392 | |
1393 | /* don't retry if called from dig */ |
1394 | if (!statp->pfcode) |
1395 | return close_and_return_error (statp, resplen2); |
1396 | __res_iclose(statp, false); |
1397 | } |
1398 | if (anhp->rcode == NOERROR && anhp->ancount == 0 |
1399 | && anhp->aa == 0 && anhp->ra == 0 && anhp->arcount == 0) { |
1400 | DprintQ(statp->options & RES_DEBUG, |
1401 | (stdout, "referred query:\n" ), |
1402 | *thisansp, |
1403 | (*thisresplenp > *thisanssizp) |
1404 | ? *thisanssizp : *thisresplenp); |
1405 | goto next_ns; |
1406 | } |
1407 | if (!(statp->options & RES_IGNTC) && anhp->tc) { |
1408 | /* |
1409 | * To get the rest of answer, |
1410 | * use TCP with same server. |
1411 | */ |
1412 | Dprint(statp->options & RES_DEBUG, |
1413 | (stdout, ";; truncated answer\n" )); |
1414 | *v_circuit = 1; |
1415 | __res_iclose(statp, false); |
1416 | // XXX if we have received one reply we could |
1417 | // XXX use it and not repeat it over TCP... |
1418 | if (resplen2 != NULL) |
1419 | *resplen2 = 0; |
1420 | return (1); |
1421 | } |
1422 | /* Mark which reply we received. */ |
1423 | if (recvresp1 == 0 && hp->id == anhp->id) |
1424 | recvresp1 = 1; |
1425 | else |
1426 | recvresp2 = 1; |
1427 | /* Repeat waiting if we have a second answer to arrive. */ |
1428 | if ((recvresp1 & recvresp2) == 0) { |
1429 | if (single_request) { |
1430 | pfd[0].events = POLLOUT; |
1431 | if (single_request_reopen) { |
1432 | __res_iclose (statp, false); |
1433 | retval = reopen (statp, terrno, ns); |
1434 | if (retval <= 0) |
1435 | { |
1436 | if (resplen2 != NULL) |
1437 | *resplen2 = 0; |
1438 | return retval; |
1439 | } |
1440 | pfd[0].fd = EXT(statp).nssocks[ns]; |
1441 | } |
1442 | } |
1443 | goto wait; |
1444 | } |
1445 | /* All is well. We have received both responses (if |
1446 | two responses were requested). */ |
1447 | return (resplen); |
1448 | } else if (pfd[0].revents & (POLLERR | POLLHUP | POLLNVAL)) |
1449 | /* Something went wrong. We can stop trying. */ |
1450 | return close_and_return_error (statp, resplen2); |
1451 | else { |
1452 | /* poll should not have returned > 0 in this case. */ |
1453 | abort (); |
1454 | } |
1455 | } |
1456 | |
1457 | #ifdef DEBUG |
1458 | static void |
1459 | Aerror(const res_state statp, FILE *file, const char *string, int error, |
1460 | const struct sockaddr *address) |
1461 | { |
1462 | int save = errno; |
1463 | |
1464 | if ((statp->options & RES_DEBUG) != 0) { |
1465 | char tmp[sizeof "xxxx.xxxx.xxxx.255.255.255.255" ]; |
1466 | |
1467 | fprintf(file, "res_send: %s ([%s].%u): %s\n" , |
1468 | string, |
1469 | (address->sa_family == AF_INET |
1470 | ? inet_ntop(address->sa_family, |
1471 | &((const struct sockaddr_in *) address)->sin_addr, |
1472 | tmp, sizeof tmp) |
1473 | : inet_ntop(address->sa_family, |
1474 | &((const struct sockaddr_in6 *) address)->sin6_addr, |
1475 | tmp, sizeof tmp)), |
1476 | (address->sa_family == AF_INET |
1477 | ? ntohs(((struct sockaddr_in *) address)->sin_port) |
1478 | : address->sa_family == AF_INET6 |
1479 | ? ntohs(((struct sockaddr_in6 *) address)->sin6_port) |
1480 | : 0), |
1481 | strerror(error)); |
1482 | } |
1483 | __set_errno (save); |
1484 | } |
1485 | |
1486 | static void |
1487 | Perror(const res_state statp, FILE *file, const char *string, int error) { |
1488 | int save = errno; |
1489 | |
1490 | if ((statp->options & RES_DEBUG) != 0) |
1491 | fprintf(file, "res_send: %s: %s\n" , |
1492 | string, strerror(error)); |
1493 | __set_errno (save); |
1494 | } |
1495 | #endif |
1496 | |
1497 | static int |
1498 | sock_eq(struct sockaddr_in6 *a1, struct sockaddr_in6 *a2) { |
1499 | if (a1->sin6_family == a2->sin6_family) { |
1500 | if (a1->sin6_family == AF_INET) |
1501 | return ((((struct sockaddr_in *)a1)->sin_port == |
1502 | ((struct sockaddr_in *)a2)->sin_port) && |
1503 | (((struct sockaddr_in *)a1)->sin_addr.s_addr == |
1504 | ((struct sockaddr_in *)a2)->sin_addr.s_addr)); |
1505 | else |
1506 | return ((a1->sin6_port == a2->sin6_port) && |
1507 | !memcmp(&a1->sin6_addr, &a2->sin6_addr, |
1508 | sizeof (struct in6_addr))); |
1509 | } |
1510 | if (a1->sin6_family == AF_INET) { |
1511 | struct sockaddr_in6 *sap = a1; |
1512 | a1 = a2; |
1513 | a2 = sap; |
1514 | } /* assumes that AF_INET and AF_INET6 are the only possibilities */ |
1515 | return ((a1->sin6_port == ((struct sockaddr_in *)a2)->sin_port) && |
1516 | IN6_IS_ADDR_V4MAPPED(&a1->sin6_addr) && |
1517 | (a1->sin6_addr.s6_addr32[3] == |
1518 | ((struct sockaddr_in *)a2)->sin_addr.s_addr)); |
1519 | } |
1520 | |