1 | /* Copyright (C) 1996-2016 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | Extended from original form by Ulrich Drepper <drepper@cygnus.com>, 1996. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | /* Parts of this file are plain copies of the file `gethtnamadr.c' from |
20 | the bind package and it has the following copyright. */ |
21 | |
22 | /* |
23 | * ++Copyright++ 1985, 1988, 1993 |
24 | * - |
25 | * Copyright (c) 1985, 1988, 1993 |
26 | * The Regents of the University of California. All rights reserved. |
27 | * |
28 | * Redistribution and use in source and binary forms, with or without |
29 | * modification, are permitted provided that the following conditions |
30 | * are met: |
31 | * 1. Redistributions of source code must retain the above copyright |
32 | * notice, this list of conditions and the following disclaimer. |
33 | * 2. Redistributions in binary form must reproduce the above copyright |
34 | * notice, this list of conditions and the following disclaimer in the |
35 | * documentation and/or other materials provided with the distribution. |
36 | * 4. Neither the name of the University nor the names of its contributors |
37 | * may be used to endorse or promote products derived from this software |
38 | * without specific prior written permission. |
39 | * |
40 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
41 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
42 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
43 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
44 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
45 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
46 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
47 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
48 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
49 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
50 | * SUCH DAMAGE. |
51 | * - |
52 | * Portions Copyright (c) 1993 by Digital Equipment Corporation. |
53 | * |
54 | * Permission to use, copy, modify, and distribute this software for any |
55 | * purpose with or without fee is hereby granted, provided that the above |
56 | * copyright notice and this permission notice appear in all copies, and that |
57 | * the name of Digital Equipment Corporation not be used in advertising or |
58 | * publicity pertaining to distribution of the document or software without |
59 | * specific, written prior permission. |
60 | * |
61 | * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL |
62 | * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES |
63 | * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT |
64 | * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL |
65 | * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR |
66 | * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS |
67 | * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
68 | * SOFTWARE. |
69 | * - |
70 | * --Copyright-- |
71 | */ |
72 | |
73 | #include <assert.h> |
74 | #include <ctype.h> |
75 | #include <errno.h> |
76 | #include <netdb.h> |
77 | #include <stdio.h> |
78 | #include <stdlib.h> |
79 | #include <stddef.h> |
80 | #include <string.h> |
81 | |
82 | #include "nsswitch.h" |
83 | |
84 | /* Get implementation for some internal functions. */ |
85 | #include <resolv/mapv4v6addr.h> |
86 | #include <resolv/mapv4v6hostent.h> |
87 | |
88 | #define RESOLVSORT |
89 | |
90 | #if PACKETSZ > 65536 |
91 | # define MAXPACKET PACKETSZ |
92 | #else |
93 | # define MAXPACKET 65536 |
94 | #endif |
95 | /* As per RFC 1034 and 1035 a host name cannot exceed 255 octets in length. */ |
96 | #ifdef MAXHOSTNAMELEN |
97 | # undef MAXHOSTNAMELEN |
98 | #endif |
99 | #define MAXHOSTNAMELEN 256 |
100 | |
101 | /* We need this time later. */ |
102 | typedef union querybuf |
103 | { |
104 | HEADER hdr; |
105 | u_char buf[MAXPACKET]; |
106 | } querybuf; |
107 | |
108 | /* These functions are defined in res_comp.c. */ |
109 | #define NS_MAXCDNAME 255 /* maximum compressed domain name */ |
110 | extern int __ns_name_ntop (const u_char *, char *, size_t); |
111 | extern int __ns_name_unpack (const u_char *, const u_char *, |
112 | const u_char *, u_char *, size_t); |
113 | |
114 | |
115 | static enum nss_status getanswer_r (const querybuf *answer, int anslen, |
116 | const char *qname, int qtype, |
117 | struct hostent *result, char *buffer, |
118 | size_t buflen, int *errnop, int *h_errnop, |
119 | int map, int32_t *ttlp, char **canonp); |
120 | |
121 | static enum nss_status gaih_getanswer (const querybuf *answer1, int anslen1, |
122 | const querybuf *answer2, int anslen2, |
123 | const char *qname, |
124 | struct gaih_addrtuple **pat, |
125 | char *buffer, size_t buflen, |
126 | int *errnop, int *h_errnop, |
127 | int32_t *ttlp); |
128 | |
129 | extern enum nss_status _nss_dns_gethostbyname3_r (const char *name, int af, |
130 | struct hostent *result, |
131 | char *buffer, size_t buflen, |
132 | int *errnop, int *h_errnop, |
133 | int32_t *ttlp, |
134 | char **canonp); |
135 | hidden_proto (_nss_dns_gethostbyname3_r) |
136 | |
137 | /* Return the expected RDATA length for an address record type (A or |
138 | AAAA). */ |
139 | static int |
140 | rrtype_to_rdata_length (int type) |
141 | { |
142 | switch (type) |
143 | { |
144 | case T_A: |
145 | return INADDRSZ; |
146 | case T_AAAA: |
147 | return IN6ADDRSZ; |
148 | default: |
149 | return -1; |
150 | } |
151 | } |
152 | |
153 | enum nss_status |
154 | _nss_dns_gethostbyname3_r (const char *name, int af, struct hostent *result, |
155 | char *buffer, size_t buflen, int *errnop, |
156 | int *h_errnop, int32_t *ttlp, char **canonp) |
157 | { |
158 | union |
159 | { |
160 | querybuf *buf; |
161 | u_char *ptr; |
162 | } host_buffer; |
163 | querybuf *orig_host_buffer; |
164 | char tmp[NS_MAXDNAME]; |
165 | int size, type, n; |
166 | const char *cp; |
167 | int map = 0; |
168 | int olderr = errno; |
169 | enum nss_status status; |
170 | |
171 | if (__res_maybe_init (&_res, 0) == -1) |
172 | return NSS_STATUS_UNAVAIL; |
173 | |
174 | switch (af) { |
175 | case AF_INET: |
176 | size = INADDRSZ; |
177 | type = T_A; |
178 | break; |
179 | case AF_INET6: |
180 | size = IN6ADDRSZ; |
181 | type = T_AAAA; |
182 | break; |
183 | default: |
184 | *h_errnop = NO_DATA; |
185 | *errnop = EAFNOSUPPORT; |
186 | return NSS_STATUS_UNAVAIL; |
187 | } |
188 | |
189 | result->h_addrtype = af; |
190 | result->h_length = size; |
191 | |
192 | /* |
193 | * if there aren't any dots, it could be a user-level alias. |
194 | * this is also done in res_query() since we are not the only |
195 | * function that looks up host names. |
196 | */ |
197 | if (strchr (name, '.') == NULL |
198 | && (cp = res_hostalias (&_res, name, tmp, sizeof (tmp))) != NULL) |
199 | name = cp; |
200 | |
201 | host_buffer.buf = orig_host_buffer = (querybuf *) alloca (1024); |
202 | |
203 | n = __libc_res_nsearch (&_res, name, C_IN, type, host_buffer.buf->buf, |
204 | 1024, &host_buffer.ptr, NULL, NULL, NULL, NULL); |
205 | if (n < 0) |
206 | { |
207 | switch (errno) |
208 | { |
209 | case ESRCH: |
210 | status = NSS_STATUS_TRYAGAIN; |
211 | h_errno = TRY_AGAIN; |
212 | break; |
213 | /* System has run out of file descriptors. */ |
214 | case EMFILE: |
215 | case ENFILE: |
216 | h_errno = NETDB_INTERNAL; |
217 | /* Fall through. */ |
218 | case ECONNREFUSED: |
219 | case ETIMEDOUT: |
220 | status = NSS_STATUS_UNAVAIL; |
221 | break; |
222 | default: |
223 | status = NSS_STATUS_NOTFOUND; |
224 | break; |
225 | } |
226 | *h_errnop = h_errno; |
227 | if (h_errno == TRY_AGAIN) |
228 | *errnop = EAGAIN; |
229 | else |
230 | __set_errno (olderr); |
231 | |
232 | /* If we are looking for an IPv6 address and mapping is enabled |
233 | by having the RES_USE_INET6 bit in _res.options set, we try |
234 | another lookup. */ |
235 | if (af == AF_INET6 && (_res.options & RES_USE_INET6)) |
236 | n = __libc_res_nsearch (&_res, name, C_IN, T_A, host_buffer.buf->buf, |
237 | host_buffer.buf != orig_host_buffer |
238 | ? MAXPACKET : 1024, &host_buffer.ptr, |
239 | NULL, NULL, NULL, NULL); |
240 | |
241 | if (n < 0) |
242 | { |
243 | if (host_buffer.buf != orig_host_buffer) |
244 | free (host_buffer.buf); |
245 | return status; |
246 | } |
247 | |
248 | map = 1; |
249 | |
250 | result->h_addrtype = AF_INET; |
251 | result->h_length = INADDRSZ; |
252 | } |
253 | |
254 | status = getanswer_r (host_buffer.buf, n, name, type, result, buffer, buflen, |
255 | errnop, h_errnop, map, ttlp, canonp); |
256 | if (host_buffer.buf != orig_host_buffer) |
257 | free (host_buffer.buf); |
258 | return status; |
259 | } |
260 | hidden_def (_nss_dns_gethostbyname3_r) |
261 | |
262 | |
263 | enum nss_status |
264 | _nss_dns_gethostbyname2_r (const char *name, int af, struct hostent *result, |
265 | char *buffer, size_t buflen, int *errnop, |
266 | int *h_errnop) |
267 | { |
268 | return _nss_dns_gethostbyname3_r (name, af, result, buffer, buflen, errnop, |
269 | h_errnop, NULL, NULL); |
270 | } |
271 | |
272 | |
273 | enum nss_status |
274 | _nss_dns_gethostbyname_r (const char *name, struct hostent *result, |
275 | char *buffer, size_t buflen, int *errnop, |
276 | int *h_errnop) |
277 | { |
278 | enum nss_status status = NSS_STATUS_NOTFOUND; |
279 | |
280 | if (_res.options & RES_USE_INET6) |
281 | status = _nss_dns_gethostbyname3_r (name, AF_INET6, result, buffer, |
282 | buflen, errnop, h_errnop, NULL, NULL); |
283 | if (status == NSS_STATUS_NOTFOUND) |
284 | status = _nss_dns_gethostbyname3_r (name, AF_INET, result, buffer, |
285 | buflen, errnop, h_errnop, NULL, NULL); |
286 | |
287 | return status; |
288 | } |
289 | |
290 | |
291 | enum nss_status |
292 | _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat, |
293 | char *buffer, size_t buflen, int *errnop, |
294 | int *herrnop, int32_t *ttlp) |
295 | { |
296 | if (__res_maybe_init (&_res, 0) == -1) |
297 | return NSS_STATUS_UNAVAIL; |
298 | |
299 | /* |
300 | * if there aren't any dots, it could be a user-level alias. |
301 | * this is also done in res_query() since we are not the only |
302 | * function that looks up host names. |
303 | */ |
304 | if (strchr (name, '.') == NULL) |
305 | { |
306 | char *tmp = alloca (NS_MAXDNAME); |
307 | const char *cp = res_hostalias (&_res, name, tmp, NS_MAXDNAME); |
308 | if (cp != NULL) |
309 | name = cp; |
310 | } |
311 | |
312 | union |
313 | { |
314 | querybuf *buf; |
315 | u_char *ptr; |
316 | } host_buffer; |
317 | querybuf *orig_host_buffer; |
318 | host_buffer.buf = orig_host_buffer = (querybuf *) alloca (2048); |
319 | u_char *ans2p = NULL; |
320 | int nans2p = 0; |
321 | int resplen2 = 0; |
322 | int ans2p_malloced = 0; |
323 | |
324 | int olderr = errno; |
325 | enum nss_status status; |
326 | int n = __libc_res_nsearch (&_res, name, C_IN, T_UNSPEC, |
327 | host_buffer.buf->buf, 2048, &host_buffer.ptr, |
328 | &ans2p, &nans2p, &resplen2, &ans2p_malloced); |
329 | if (n >= 0) |
330 | { |
331 | status = gaih_getanswer (host_buffer.buf, n, (const querybuf *) ans2p, |
332 | resplen2, name, pat, buffer, buflen, |
333 | errnop, herrnop, ttlp); |
334 | } |
335 | else |
336 | { |
337 | switch (errno) |
338 | { |
339 | case ESRCH: |
340 | status = NSS_STATUS_TRYAGAIN; |
341 | h_errno = TRY_AGAIN; |
342 | break; |
343 | /* System has run out of file descriptors. */ |
344 | case EMFILE: |
345 | case ENFILE: |
346 | h_errno = NETDB_INTERNAL; |
347 | /* Fall through. */ |
348 | case ECONNREFUSED: |
349 | case ETIMEDOUT: |
350 | status = NSS_STATUS_UNAVAIL; |
351 | break; |
352 | default: |
353 | status = NSS_STATUS_NOTFOUND; |
354 | break; |
355 | } |
356 | |
357 | *herrnop = h_errno; |
358 | if (h_errno == TRY_AGAIN) |
359 | *errnop = EAGAIN; |
360 | else |
361 | __set_errno (olderr); |
362 | } |
363 | |
364 | /* Check whether ans2p was separately allocated. */ |
365 | if (ans2p_malloced) |
366 | free (ans2p); |
367 | |
368 | if (host_buffer.buf != orig_host_buffer) |
369 | free (host_buffer.buf); |
370 | |
371 | return status; |
372 | } |
373 | |
374 | |
375 | extern enum nss_status _nss_dns_gethostbyaddr2_r (const void *addr, |
376 | socklen_t len, int af, |
377 | struct hostent *result, |
378 | char *buffer, size_t buflen, |
379 | int *errnop, int *h_errnop, |
380 | int32_t *ttlp); |
381 | hidden_proto (_nss_dns_gethostbyaddr2_r) |
382 | |
383 | enum nss_status |
384 | _nss_dns_gethostbyaddr2_r (const void *addr, socklen_t len, int af, |
385 | struct hostent *result, char *buffer, size_t buflen, |
386 | int *errnop, int *h_errnop, int32_t *ttlp) |
387 | { |
388 | static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff }; |
389 | static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 }; |
390 | static const u_char v6local[] = { 0,0, 0,1 }; |
391 | const u_char *uaddr = (const u_char *)addr; |
392 | struct host_data |
393 | { |
394 | char *aliases[MAX_NR_ALIASES]; |
395 | unsigned char host_addr[16]; /* IPv4 or IPv6 */ |
396 | char *h_addr_ptrs[MAX_NR_ADDRS + 1]; |
397 | char linebuffer[0]; |
398 | } *host_data = (struct host_data *) buffer; |
399 | union |
400 | { |
401 | querybuf *buf; |
402 | u_char *ptr; |
403 | } host_buffer; |
404 | querybuf *orig_host_buffer; |
405 | char qbuf[MAXDNAME+1], *qp = NULL; |
406 | size_t size; |
407 | int n, status; |
408 | int olderr = errno; |
409 | |
410 | uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct host_data); |
411 | buffer += pad; |
412 | buflen = buflen > pad ? buflen - pad : 0; |
413 | |
414 | if (__glibc_unlikely (buflen < sizeof (struct host_data))) |
415 | { |
416 | *errnop = ERANGE; |
417 | *h_errnop = NETDB_INTERNAL; |
418 | return NSS_STATUS_TRYAGAIN; |
419 | } |
420 | |
421 | host_data = (struct host_data *) buffer; |
422 | |
423 | if (__res_maybe_init (&_res, 0) == -1) |
424 | return NSS_STATUS_UNAVAIL; |
425 | |
426 | if (af == AF_INET6 && len == IN6ADDRSZ |
427 | && (memcmp (uaddr, mapped, sizeof mapped) == 0 |
428 | || (memcmp (uaddr, tunnelled, sizeof tunnelled) == 0 |
429 | && memcmp (&uaddr[sizeof tunnelled], v6local, sizeof v6local)))) |
430 | { |
431 | /* Unmap. */ |
432 | addr += sizeof mapped; |
433 | uaddr += sizeof mapped; |
434 | af = AF_INET; |
435 | len = INADDRSZ; |
436 | } |
437 | |
438 | switch (af) |
439 | { |
440 | case AF_INET: |
441 | size = INADDRSZ; |
442 | break; |
443 | case AF_INET6: |
444 | size = IN6ADDRSZ; |
445 | break; |
446 | default: |
447 | *errnop = EAFNOSUPPORT; |
448 | *h_errnop = NETDB_INTERNAL; |
449 | return NSS_STATUS_UNAVAIL; |
450 | } |
451 | if (size > len) |
452 | { |
453 | *errnop = EAFNOSUPPORT; |
454 | *h_errnop = NETDB_INTERNAL; |
455 | return NSS_STATUS_UNAVAIL; |
456 | } |
457 | |
458 | host_buffer.buf = orig_host_buffer = (querybuf *) alloca (1024); |
459 | |
460 | switch (af) |
461 | { |
462 | case AF_INET: |
463 | sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa" , (uaddr[3] & 0xff), |
464 | (uaddr[2] & 0xff), (uaddr[1] & 0xff), (uaddr[0] & 0xff)); |
465 | break; |
466 | case AF_INET6: |
467 | /* Only lookup with the byte string format if the user wants it. */ |
468 | if (__glibc_unlikely (_res.options & RES_USEBSTRING)) |
469 | { |
470 | qp = stpcpy (qbuf, "\\[x" ); |
471 | for (n = 0; n < IN6ADDRSZ; ++n) |
472 | qp += sprintf (qp, "%02hhx" , uaddr[n]); |
473 | strcpy (qp, "].ip6.arpa" ); |
474 | n = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, |
475 | host_buffer.buf->buf, 1024, &host_buffer.ptr, |
476 | NULL, NULL, NULL, NULL); |
477 | if (n >= 0) |
478 | goto got_it_already; |
479 | } |
480 | qp = qbuf; |
481 | for (n = IN6ADDRSZ - 1; n >= 0; n--) |
482 | { |
483 | static const char nibblechar[16] = "0123456789abcdef" ; |
484 | *qp++ = nibblechar[uaddr[n] & 0xf]; |
485 | *qp++ = '.'; |
486 | *qp++ = nibblechar[(uaddr[n] >> 4) & 0xf]; |
487 | *qp++ = '.'; |
488 | } |
489 | strcpy(qp, "ip6.arpa" ); |
490 | break; |
491 | default: |
492 | /* Cannot happen. */ |
493 | break; |
494 | } |
495 | |
496 | n = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, host_buffer.buf->buf, |
497 | 1024, &host_buffer.ptr, NULL, NULL, NULL, NULL); |
498 | if (n < 0 && af == AF_INET6 && (_res.options & RES_NOIP6DOTINT) == 0) |
499 | { |
500 | strcpy (qp, "ip6.int" ); |
501 | n = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, host_buffer.buf->buf, |
502 | host_buffer.buf != orig_host_buffer |
503 | ? MAXPACKET : 1024, &host_buffer.ptr, |
504 | NULL, NULL, NULL, NULL); |
505 | } |
506 | if (n < 0) |
507 | { |
508 | *h_errnop = h_errno; |
509 | __set_errno (olderr); |
510 | if (host_buffer.buf != orig_host_buffer) |
511 | free (host_buffer.buf); |
512 | return errno == ECONNREFUSED ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND; |
513 | } |
514 | |
515 | got_it_already: |
516 | status = getanswer_r (host_buffer.buf, n, qbuf, T_PTR, result, buffer, buflen, |
517 | errnop, h_errnop, 0 /* XXX */, ttlp, NULL); |
518 | if (host_buffer.buf != orig_host_buffer) |
519 | free (host_buffer.buf); |
520 | if (status != NSS_STATUS_SUCCESS) |
521 | return status; |
522 | |
523 | #ifdef SUNSECURITY |
524 | This is not implemented because it is not possible to use the current |
525 | source from bind in a multi-threaded program. |
526 | #endif |
527 | |
528 | result->h_addrtype = af; |
529 | result->h_length = len; |
530 | memcpy (host_data->host_addr, addr, len); |
531 | host_data->h_addr_ptrs[0] = (char *) host_data->host_addr; |
532 | host_data->h_addr_ptrs[1] = NULL; |
533 | #if 0 |
534 | /* XXX I think this is wrong. Why should an IPv4 address be |
535 | converted to IPv6 if the user explicitly asked for IPv4? */ |
536 | if (af == AF_INET && (_res.options & RES_USE_INET6)) |
537 | { |
538 | map_v4v6_address ((char *) host_data->host_addr, |
539 | (char *) host_data->host_addr); |
540 | result->h_addrtype = AF_INET6; |
541 | result->h_length = IN6ADDRSZ; |
542 | } |
543 | #endif |
544 | *h_errnop = NETDB_SUCCESS; |
545 | return NSS_STATUS_SUCCESS; |
546 | } |
547 | hidden_def (_nss_dns_gethostbyaddr2_r) |
548 | |
549 | |
550 | enum nss_status |
551 | _nss_dns_gethostbyaddr_r (const void *addr, socklen_t len, int af, |
552 | struct hostent *result, char *buffer, size_t buflen, |
553 | int *errnop, int *h_errnop) |
554 | { |
555 | return _nss_dns_gethostbyaddr2_r (addr, len, af, result, buffer, buflen, |
556 | errnop, h_errnop, NULL); |
557 | } |
558 | |
559 | #ifdef RESOLVSORT |
560 | static void addrsort (char **ap, int num); |
561 | |
562 | static void |
563 | addrsort (char **ap, int num) |
564 | { |
565 | int i, j; |
566 | char **p; |
567 | short aval[MAX_NR_ADDRS]; |
568 | int needsort = 0; |
569 | |
570 | p = ap; |
571 | if (num > MAX_NR_ADDRS) |
572 | num = MAX_NR_ADDRS; |
573 | for (i = 0; i < num; i++, p++) |
574 | { |
575 | for (j = 0 ; (unsigned)j < _res.nsort; j++) |
576 | if (_res.sort_list[j].addr.s_addr == |
577 | (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask)) |
578 | break; |
579 | aval[i] = j; |
580 | if (needsort == 0 && i > 0 && j < aval[i-1]) |
581 | needsort = i; |
582 | } |
583 | if (!needsort) |
584 | return; |
585 | |
586 | while (needsort++ < num) |
587 | for (j = needsort - 2; j >= 0; j--) |
588 | if (aval[j] > aval[j+1]) |
589 | { |
590 | char *hp; |
591 | |
592 | i = aval[j]; |
593 | aval[j] = aval[j+1]; |
594 | aval[j+1] = i; |
595 | |
596 | hp = ap[j]; |
597 | ap[j] = ap[j+1]; |
598 | ap[j+1] = hp; |
599 | } |
600 | else |
601 | break; |
602 | } |
603 | #endif |
604 | |
605 | static enum nss_status |
606 | getanswer_r (const querybuf *answer, int anslen, const char *qname, int qtype, |
607 | struct hostent *result, char *buffer, size_t buflen, |
608 | int *errnop, int *h_errnop, int map, int32_t *ttlp, char **canonp) |
609 | { |
610 | struct host_data |
611 | { |
612 | char *aliases[MAX_NR_ALIASES]; |
613 | unsigned char host_addr[16]; /* IPv4 or IPv6 */ |
614 | char *h_addr_ptrs[0]; |
615 | } *host_data; |
616 | int linebuflen; |
617 | const HEADER *hp; |
618 | const u_char *end_of_message, *cp; |
619 | int n, ancount, qdcount; |
620 | int haveanswer, had_error; |
621 | char *bp, **ap, **hap; |
622 | char tbuf[MAXDNAME]; |
623 | const char *tname; |
624 | int (*name_ok) (const char *); |
625 | u_char packtmp[NS_MAXCDNAME]; |
626 | int have_to_map = 0; |
627 | uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct host_data); |
628 | buffer += pad; |
629 | buflen = buflen > pad ? buflen - pad : 0; |
630 | if (__glibc_unlikely (buflen < sizeof (struct host_data))) |
631 | { |
632 | /* The buffer is too small. */ |
633 | too_small: |
634 | *errnop = ERANGE; |
635 | *h_errnop = NETDB_INTERNAL; |
636 | return NSS_STATUS_TRYAGAIN; |
637 | } |
638 | host_data = (struct host_data *) buffer; |
639 | linebuflen = buflen - sizeof (struct host_data); |
640 | if (buflen - sizeof (struct host_data) != linebuflen) |
641 | linebuflen = INT_MAX; |
642 | |
643 | tname = qname; |
644 | result->h_name = NULL; |
645 | end_of_message = answer->buf + anslen; |
646 | switch (qtype) |
647 | { |
648 | case T_A: |
649 | case T_AAAA: |
650 | name_ok = res_hnok; |
651 | break; |
652 | case T_PTR: |
653 | name_ok = res_dnok; |
654 | break; |
655 | default: |
656 | *errnop = ENOENT; |
657 | return NSS_STATUS_UNAVAIL; /* XXX should be abort(); */ |
658 | } |
659 | |
660 | /* |
661 | * find first satisfactory answer |
662 | */ |
663 | hp = &answer->hdr; |
664 | ancount = ntohs (hp->ancount); |
665 | qdcount = ntohs (hp->qdcount); |
666 | cp = answer->buf + HFIXEDSZ; |
667 | if (__builtin_expect (qdcount, 1) != 1) |
668 | { |
669 | *h_errnop = NO_RECOVERY; |
670 | return NSS_STATUS_UNAVAIL; |
671 | } |
672 | if (sizeof (struct host_data) + (ancount + 1) * sizeof (char *) >= buflen) |
673 | goto too_small; |
674 | bp = (char *) &host_data->h_addr_ptrs[ancount + 1]; |
675 | linebuflen -= (ancount + 1) * sizeof (char *); |
676 | |
677 | n = __ns_name_unpack (answer->buf, end_of_message, cp, |
678 | packtmp, sizeof packtmp); |
679 | if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1) |
680 | { |
681 | if (__builtin_expect (errno, 0) == EMSGSIZE) |
682 | goto too_small; |
683 | |
684 | n = -1; |
685 | } |
686 | |
687 | if (n > 0 && bp[0] == '.') |
688 | bp[0] = '\0'; |
689 | |
690 | if (__builtin_expect (n < 0 || ((*name_ok) (bp) == 0 && (errno = EBADMSG)), |
691 | 0)) |
692 | { |
693 | *errnop = errno; |
694 | *h_errnop = NO_RECOVERY; |
695 | return NSS_STATUS_UNAVAIL; |
696 | } |
697 | cp += n + QFIXEDSZ; |
698 | |
699 | if (qtype == T_A || qtype == T_AAAA) |
700 | { |
701 | /* res_send() has already verified that the query name is the |
702 | * same as the one we sent; this just gets the expanded name |
703 | * (i.e., with the succeeding search-domain tacked on). |
704 | */ |
705 | n = strlen (bp) + 1; /* for the \0 */ |
706 | if (n >= MAXHOSTNAMELEN) |
707 | { |
708 | *h_errnop = NO_RECOVERY; |
709 | *errnop = ENOENT; |
710 | return NSS_STATUS_TRYAGAIN; |
711 | } |
712 | result->h_name = bp; |
713 | bp += n; |
714 | linebuflen -= n; |
715 | if (linebuflen < 0) |
716 | goto too_small; |
717 | /* The qname can be abbreviated, but h_name is now absolute. */ |
718 | qname = result->h_name; |
719 | } |
720 | |
721 | ap = host_data->aliases; |
722 | *ap = NULL; |
723 | result->h_aliases = host_data->aliases; |
724 | hap = host_data->h_addr_ptrs; |
725 | *hap = NULL; |
726 | result->h_addr_list = host_data->h_addr_ptrs; |
727 | haveanswer = 0; |
728 | had_error = 0; |
729 | |
730 | while (ancount-- > 0 && cp < end_of_message && had_error == 0) |
731 | { |
732 | int type, class; |
733 | |
734 | n = __ns_name_unpack (answer->buf, end_of_message, cp, |
735 | packtmp, sizeof packtmp); |
736 | if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1) |
737 | { |
738 | if (__builtin_expect (errno, 0) == EMSGSIZE) |
739 | goto too_small; |
740 | |
741 | n = -1; |
742 | } |
743 | |
744 | if (__glibc_unlikely (n < 0 || (*name_ok) (bp) == 0)) |
745 | { |
746 | ++had_error; |
747 | continue; |
748 | } |
749 | cp += n; /* name */ |
750 | |
751 | if (__glibc_unlikely (cp + 10 > end_of_message)) |
752 | { |
753 | ++had_error; |
754 | continue; |
755 | } |
756 | |
757 | type = __ns_get16 (cp); |
758 | cp += INT16SZ; /* type */ |
759 | class = __ns_get16 (cp); |
760 | cp += INT16SZ; /* class */ |
761 | int32_t ttl = __ns_get32 (cp); |
762 | cp += INT32SZ; /* TTL */ |
763 | n = __ns_get16 (cp); |
764 | cp += INT16SZ; /* len */ |
765 | |
766 | if (end_of_message - cp < n) |
767 | { |
768 | /* RDATA extends beyond the end of the packet. */ |
769 | ++had_error; |
770 | continue; |
771 | } |
772 | |
773 | if (__glibc_unlikely (class != C_IN)) |
774 | { |
775 | /* XXX - debug? syslog? */ |
776 | cp += n; |
777 | continue; /* XXX - had_error++ ? */ |
778 | } |
779 | |
780 | if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) |
781 | { |
782 | /* A CNAME could also have a TTL entry. */ |
783 | if (ttlp != NULL && ttl < *ttlp) |
784 | *ttlp = ttl; |
785 | |
786 | if (ap >= &host_data->aliases[MAX_NR_ALIASES - 1]) |
787 | continue; |
788 | n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf); |
789 | if (__glibc_unlikely (n < 0 || (*name_ok) (tbuf) == 0)) |
790 | { |
791 | ++had_error; |
792 | continue; |
793 | } |
794 | cp += n; |
795 | /* Store alias. */ |
796 | *ap++ = bp; |
797 | n = strlen (bp) + 1; /* For the \0. */ |
798 | if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN) |
799 | { |
800 | ++had_error; |
801 | continue; |
802 | } |
803 | bp += n; |
804 | linebuflen -= n; |
805 | /* Get canonical name. */ |
806 | n = strlen (tbuf) + 1; /* For the \0. */ |
807 | if (__glibc_unlikely (n > linebuflen)) |
808 | goto too_small; |
809 | if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN) |
810 | { |
811 | ++had_error; |
812 | continue; |
813 | } |
814 | result->h_name = bp; |
815 | bp = __mempcpy (bp, tbuf, n); /* Cannot overflow. */ |
816 | linebuflen -= n; |
817 | continue; |
818 | } |
819 | |
820 | if (qtype == T_PTR && type == T_CNAME) |
821 | { |
822 | /* A CNAME could also have a TTL entry. */ |
823 | if (ttlp != NULL && ttl < *ttlp) |
824 | *ttlp = ttl; |
825 | |
826 | n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf); |
827 | if (__glibc_unlikely (n < 0 || res_dnok (tbuf) == 0)) |
828 | { |
829 | ++had_error; |
830 | continue; |
831 | } |
832 | cp += n; |
833 | /* Get canonical name. */ |
834 | n = strlen (tbuf) + 1; /* For the \0. */ |
835 | if (__glibc_unlikely (n > linebuflen)) |
836 | goto too_small; |
837 | if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN) |
838 | { |
839 | ++had_error; |
840 | continue; |
841 | } |
842 | tname = bp; |
843 | bp = __mempcpy (bp, tbuf, n); /* Cannot overflow. */ |
844 | linebuflen -= n; |
845 | continue; |
846 | } |
847 | |
848 | if (type == T_A && qtype == T_AAAA && map) |
849 | have_to_map = 1; |
850 | else if (__glibc_unlikely (type != qtype)) |
851 | { |
852 | cp += n; |
853 | continue; /* XXX - had_error++ ? */ |
854 | } |
855 | |
856 | switch (type) |
857 | { |
858 | case T_PTR: |
859 | if (__glibc_unlikely (strcasecmp (tname, bp) != 0)) |
860 | { |
861 | cp += n; |
862 | continue; /* XXX - had_error++ ? */ |
863 | } |
864 | |
865 | n = __ns_name_unpack (answer->buf, end_of_message, cp, |
866 | packtmp, sizeof packtmp); |
867 | if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1) |
868 | { |
869 | if (__builtin_expect (errno, 0) == EMSGSIZE) |
870 | goto too_small; |
871 | |
872 | n = -1; |
873 | } |
874 | |
875 | if (__glibc_unlikely (n < 0 || res_hnok (bp) == 0)) |
876 | { |
877 | ++had_error; |
878 | break; |
879 | } |
880 | if (ttlp != NULL && ttl < *ttlp) |
881 | *ttlp = ttl; |
882 | /* bind would put multiple PTR records as aliases, but we don't do |
883 | that. */ |
884 | result->h_name = bp; |
885 | if (have_to_map) |
886 | { |
887 | n = strlen (bp) + 1; /* for the \0 */ |
888 | if (__glibc_unlikely (n >= MAXHOSTNAMELEN)) |
889 | { |
890 | ++had_error; |
891 | break; |
892 | } |
893 | bp += n; |
894 | linebuflen -= n; |
895 | if (map_v4v6_hostent (result, &bp, &linebuflen)) |
896 | goto too_small; |
897 | } |
898 | *h_errnop = NETDB_SUCCESS; |
899 | return NSS_STATUS_SUCCESS; |
900 | case T_A: |
901 | case T_AAAA: |
902 | if (__builtin_expect (strcasecmp (result->h_name, bp), 0) != 0) |
903 | { |
904 | cp += n; |
905 | continue; /* XXX - had_error++ ? */ |
906 | } |
907 | |
908 | /* Stop parsing at a record whose length is incorrect. */ |
909 | if (n != rrtype_to_rdata_length (type)) |
910 | { |
911 | ++had_error; |
912 | break; |
913 | } |
914 | |
915 | /* Skip records of the wrong type. */ |
916 | if (n != result->h_length) |
917 | { |
918 | cp += n; |
919 | continue; |
920 | } |
921 | if (!haveanswer) |
922 | { |
923 | int nn; |
924 | |
925 | /* We compose a single hostent out of the entire chain of |
926 | entries, so the TTL of the hostent is essentially the lowest |
927 | TTL in the chain. */ |
928 | if (ttlp != NULL && ttl < *ttlp) |
929 | *ttlp = ttl; |
930 | if (canonp != NULL) |
931 | *canonp = bp; |
932 | result->h_name = bp; |
933 | nn = strlen (bp) + 1; /* for the \0 */ |
934 | bp += nn; |
935 | linebuflen -= nn; |
936 | } |
937 | |
938 | linebuflen -= sizeof (align) - ((u_long) bp % sizeof (align)); |
939 | bp += sizeof (align) - ((u_long) bp % sizeof (align)); |
940 | |
941 | if (__glibc_unlikely (n > linebuflen)) |
942 | goto too_small; |
943 | bp = __mempcpy (*hap++ = bp, cp, n); |
944 | cp += n; |
945 | linebuflen -= n; |
946 | break; |
947 | default: |
948 | abort (); |
949 | } |
950 | if (had_error == 0) |
951 | ++haveanswer; |
952 | } |
953 | |
954 | if (haveanswer > 0) |
955 | { |
956 | *ap = NULL; |
957 | *hap = NULL; |
958 | #if defined RESOLVSORT |
959 | /* |
960 | * Note: we sort even if host can take only one address |
961 | * in its return structures - should give it the "best" |
962 | * address in that case, not some random one |
963 | */ |
964 | if (_res.nsort && haveanswer > 1 && qtype == T_A) |
965 | addrsort (host_data->h_addr_ptrs, haveanswer); |
966 | #endif /*RESOLVSORT*/ |
967 | |
968 | if (result->h_name == NULL) |
969 | { |
970 | n = strlen (qname) + 1; /* For the \0. */ |
971 | if (n > linebuflen) |
972 | goto too_small; |
973 | if (n >= MAXHOSTNAMELEN) |
974 | goto no_recovery; |
975 | result->h_name = bp; |
976 | bp = __mempcpy (bp, qname, n); /* Cannot overflow. */ |
977 | linebuflen -= n; |
978 | } |
979 | |
980 | if (have_to_map) |
981 | if (map_v4v6_hostent (result, &bp, &linebuflen)) |
982 | goto too_small; |
983 | *h_errnop = NETDB_SUCCESS; |
984 | return NSS_STATUS_SUCCESS; |
985 | } |
986 | no_recovery: |
987 | *h_errnop = NO_RECOVERY; |
988 | *errnop = ENOENT; |
989 | /* Special case here: if the resolver sent a result but it only |
990 | contains a CNAME while we are looking for a T_A or T_AAAA record, |
991 | we fail with NOTFOUND instead of TRYAGAIN. */ |
992 | return ((qtype == T_A || qtype == T_AAAA) && ap != host_data->aliases |
993 | ? NSS_STATUS_NOTFOUND : NSS_STATUS_TRYAGAIN); |
994 | } |
995 | |
996 | |
997 | static enum nss_status |
998 | gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname, |
999 | struct gaih_addrtuple ***patp, |
1000 | char **bufferp, size_t *buflenp, |
1001 | int *errnop, int *h_errnop, int32_t *ttlp, int *firstp) |
1002 | { |
1003 | char *buffer = *bufferp; |
1004 | size_t buflen = *buflenp; |
1005 | |
1006 | struct gaih_addrtuple **pat = *patp; |
1007 | const HEADER *hp = &answer->hdr; |
1008 | int ancount = ntohs (hp->ancount); |
1009 | int qdcount = ntohs (hp->qdcount); |
1010 | const u_char *cp = answer->buf + HFIXEDSZ; |
1011 | const u_char *end_of_message = answer->buf + anslen; |
1012 | if (__glibc_unlikely (qdcount != 1)) |
1013 | { |
1014 | *h_errnop = NO_RECOVERY; |
1015 | return NSS_STATUS_UNAVAIL; |
1016 | } |
1017 | |
1018 | u_char packtmp[NS_MAXCDNAME]; |
1019 | int n = __ns_name_unpack (answer->buf, end_of_message, cp, |
1020 | packtmp, sizeof packtmp); |
1021 | /* We unpack the name to check it for validity. But we do not need |
1022 | it later. */ |
1023 | if (n != -1 && __ns_name_ntop (packtmp, buffer, buflen) == -1) |
1024 | { |
1025 | if (__builtin_expect (errno, 0) == EMSGSIZE) |
1026 | { |
1027 | too_small: |
1028 | *errnop = ERANGE; |
1029 | *h_errnop = NETDB_INTERNAL; |
1030 | return NSS_STATUS_TRYAGAIN; |
1031 | } |
1032 | |
1033 | n = -1; |
1034 | } |
1035 | |
1036 | if (__builtin_expect (n < 0 || (res_hnok (buffer) == 0 |
1037 | && (errno = EBADMSG)), 0)) |
1038 | { |
1039 | *errnop = errno; |
1040 | *h_errnop = NO_RECOVERY; |
1041 | return NSS_STATUS_UNAVAIL; |
1042 | } |
1043 | cp += n + QFIXEDSZ; |
1044 | |
1045 | int haveanswer = 0; |
1046 | int had_error = 0; |
1047 | char *canon = NULL; |
1048 | char *h_name = NULL; |
1049 | int h_namelen = 0; |
1050 | |
1051 | if (ancount == 0) |
1052 | { |
1053 | *h_errnop = HOST_NOT_FOUND; |
1054 | return NSS_STATUS_NOTFOUND; |
1055 | } |
1056 | |
1057 | while (ancount-- > 0 && cp < end_of_message && had_error == 0) |
1058 | { |
1059 | n = __ns_name_unpack (answer->buf, end_of_message, cp, |
1060 | packtmp, sizeof packtmp); |
1061 | if (n != -1 && |
1062 | (h_namelen = __ns_name_ntop (packtmp, buffer, buflen)) == -1) |
1063 | { |
1064 | if (__builtin_expect (errno, 0) == EMSGSIZE) |
1065 | goto too_small; |
1066 | |
1067 | n = -1; |
1068 | } |
1069 | if (__glibc_unlikely (n < 0 || res_hnok (buffer) == 0)) |
1070 | { |
1071 | ++had_error; |
1072 | continue; |
1073 | } |
1074 | if (*firstp && canon == NULL) |
1075 | { |
1076 | h_name = buffer; |
1077 | buffer += h_namelen; |
1078 | buflen -= h_namelen; |
1079 | } |
1080 | |
1081 | cp += n; /* name */ |
1082 | |
1083 | if (__glibc_unlikely (cp + 10 > end_of_message)) |
1084 | { |
1085 | ++had_error; |
1086 | continue; |
1087 | } |
1088 | |
1089 | int type = __ns_get16 (cp); |
1090 | cp += INT16SZ; /* type */ |
1091 | int class = __ns_get16 (cp); |
1092 | cp += INT16SZ; /* class */ |
1093 | int32_t ttl = __ns_get32 (cp); |
1094 | cp += INT32SZ; /* TTL */ |
1095 | n = __ns_get16 (cp); |
1096 | cp += INT16SZ; /* len */ |
1097 | |
1098 | if (end_of_message - cp < n) |
1099 | { |
1100 | /* RDATA extends beyond the end of the packet. */ |
1101 | ++had_error; |
1102 | continue; |
1103 | } |
1104 | |
1105 | if (class != C_IN) |
1106 | { |
1107 | cp += n; |
1108 | continue; |
1109 | } |
1110 | |
1111 | if (type == T_CNAME) |
1112 | { |
1113 | char tbuf[MAXDNAME]; |
1114 | |
1115 | /* A CNAME could also have a TTL entry. */ |
1116 | if (ttlp != NULL && ttl < *ttlp) |
1117 | *ttlp = ttl; |
1118 | |
1119 | n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf); |
1120 | if (__glibc_unlikely (n < 0 || res_hnok (tbuf) == 0)) |
1121 | { |
1122 | ++had_error; |
1123 | continue; |
1124 | } |
1125 | cp += n; |
1126 | |
1127 | if (*firstp) |
1128 | { |
1129 | /* Reclaim buffer space. */ |
1130 | if (h_name + h_namelen == buffer) |
1131 | { |
1132 | buffer = h_name; |
1133 | buflen += h_namelen; |
1134 | } |
1135 | |
1136 | n = strlen (tbuf) + 1; |
1137 | if (__glibc_unlikely (n > buflen)) |
1138 | goto too_small; |
1139 | if (__glibc_unlikely (n >= MAXHOSTNAMELEN)) |
1140 | { |
1141 | ++had_error; |
1142 | continue; |
1143 | } |
1144 | |
1145 | canon = buffer; |
1146 | buffer = __mempcpy (buffer, tbuf, n); |
1147 | buflen -= n; |
1148 | h_namelen = 0; |
1149 | } |
1150 | continue; |
1151 | } |
1152 | |
1153 | /* Stop parsing if we encounter a record with incorrect RDATA |
1154 | length. */ |
1155 | if (type == T_A || type == T_AAAA) |
1156 | { |
1157 | if (n != rrtype_to_rdata_length (type)) |
1158 | { |
1159 | ++had_error; |
1160 | continue; |
1161 | } |
1162 | } |
1163 | else |
1164 | { |
1165 | /* Skip unknown records. */ |
1166 | cp += n; |
1167 | continue; |
1168 | } |
1169 | |
1170 | assert (type == T_A || type == T_AAAA); |
1171 | if (*pat == NULL) |
1172 | { |
1173 | uintptr_t pad = (-(uintptr_t) buffer |
1174 | % __alignof__ (struct gaih_addrtuple)); |
1175 | buffer += pad; |
1176 | buflen = buflen > pad ? buflen - pad : 0; |
1177 | |
1178 | if (__builtin_expect (buflen < sizeof (struct gaih_addrtuple), |
1179 | 0)) |
1180 | goto too_small; |
1181 | |
1182 | *pat = (struct gaih_addrtuple *) buffer; |
1183 | buffer += sizeof (struct gaih_addrtuple); |
1184 | buflen -= sizeof (struct gaih_addrtuple); |
1185 | } |
1186 | |
1187 | (*pat)->name = NULL; |
1188 | (*pat)->next = NULL; |
1189 | |
1190 | if (*firstp) |
1191 | { |
1192 | /* We compose a single hostent out of the entire chain of |
1193 | entries, so the TTL of the hostent is essentially the lowest |
1194 | TTL in the chain. */ |
1195 | if (ttlp != NULL && ttl < *ttlp) |
1196 | *ttlp = ttl; |
1197 | |
1198 | (*pat)->name = canon ?: h_name; |
1199 | |
1200 | *firstp = 0; |
1201 | } |
1202 | |
1203 | (*pat)->family = type == T_A ? AF_INET : AF_INET6; |
1204 | memcpy ((*pat)->addr, cp, n); |
1205 | cp += n; |
1206 | (*pat)->scopeid = 0; |
1207 | |
1208 | pat = &((*pat)->next); |
1209 | |
1210 | haveanswer = 1; |
1211 | } |
1212 | |
1213 | if (haveanswer) |
1214 | { |
1215 | *patp = pat; |
1216 | *bufferp = buffer; |
1217 | *buflenp = buflen; |
1218 | |
1219 | *h_errnop = NETDB_SUCCESS; |
1220 | return NSS_STATUS_SUCCESS; |
1221 | } |
1222 | |
1223 | /* Special case here: if the resolver sent a result but it only |
1224 | contains a CNAME while we are looking for a T_A or T_AAAA record, |
1225 | we fail with NOTFOUND instead of TRYAGAIN. */ |
1226 | if (canon != NULL) |
1227 | { |
1228 | *h_errnop = HOST_NOT_FOUND; |
1229 | return NSS_STATUS_NOTFOUND; |
1230 | } |
1231 | |
1232 | *h_errnop = NETDB_INTERNAL; |
1233 | return NSS_STATUS_TRYAGAIN; |
1234 | } |
1235 | |
1236 | |
1237 | static enum nss_status |
1238 | gaih_getanswer (const querybuf *answer1, int anslen1, const querybuf *answer2, |
1239 | int anslen2, const char *qname, |
1240 | struct gaih_addrtuple **pat, char *buffer, size_t buflen, |
1241 | int *errnop, int *h_errnop, int32_t *ttlp) |
1242 | { |
1243 | int first = 1; |
1244 | |
1245 | enum nss_status status = NSS_STATUS_NOTFOUND; |
1246 | |
1247 | /* Combining the NSS status of two distinct queries requires some |
1248 | compromise and attention to symmetry (A or AAAA queries can be |
1249 | returned in any order). What follows is a breakdown of how this |
1250 | code is expected to work and why. We discuss only SUCCESS, |
1251 | TRYAGAIN, NOTFOUND and UNAVAIL, since they are the only returns |
1252 | that apply (though RETURN and MERGE exist). We make a distinction |
1253 | between TRYAGAIN (recoverable) and TRYAGAIN' (not-recoverable). |
1254 | A recoverable TRYAGAIN is almost always due to buffer size issues |
1255 | and returns ERANGE in errno and the caller is expected to retry |
1256 | with a larger buffer. |
1257 | |
1258 | Lastly, you may be tempted to make significant changes to the |
1259 | conditions in this code to bring about symmetry between responses. |
1260 | Please don't change anything without due consideration for |
1261 | expected application behaviour. Some of the synthesized responses |
1262 | aren't very well thought out and sometimes appear to imply that |
1263 | IPv4 responses are always answer 1, and IPv6 responses are always |
1264 | answer 2, but that's not true (see the implementation of send_dg |
1265 | and send_vc to see response can arrive in any order, particularly |
1266 | for UDP). However, we expect it holds roughly enough of the time |
1267 | that this code works, but certainly needs to be fixed to make this |
1268 | a more robust implementation. |
1269 | |
1270 | ---------------------------------------------- |
1271 | | Answer 1 Status / | Synthesized | Reason | |
1272 | | Answer 2 Status | Status | | |
1273 | |--------------------------------------------| |
1274 | | SUCCESS/SUCCESS | SUCCESS | [1] | |
1275 | | SUCCESS/TRYAGAIN | TRYAGAIN | [5] | |
1276 | | SUCCESS/TRYAGAIN' | SUCCESS | [1] | |
1277 | | SUCCESS/NOTFOUND | SUCCESS | [1] | |
1278 | | SUCCESS/UNAVAIL | SUCCESS | [1] | |
1279 | | TRYAGAIN/SUCCESS | TRYAGAIN | [2] | |
1280 | | TRYAGAIN/TRYAGAIN | TRYAGAIN | [2] | |
1281 | | TRYAGAIN/TRYAGAIN' | TRYAGAIN | [2] | |
1282 | | TRYAGAIN/NOTFOUND | TRYAGAIN | [2] | |
1283 | | TRYAGAIN/UNAVAIL | TRYAGAIN | [2] | |
1284 | | TRYAGAIN'/SUCCESS | SUCCESS | [3] | |
1285 | | TRYAGAIN'/TRYAGAIN | TRYAGAIN | [3] | |
1286 | | TRYAGAIN'/TRYAGAIN' | TRYAGAIN' | [3] | |
1287 | | TRYAGAIN'/NOTFOUND | TRYAGAIN' | [3] | |
1288 | | TRYAGAIN'/UNAVAIL | UNAVAIL | [3] | |
1289 | | NOTFOUND/SUCCESS | SUCCESS | [3] | |
1290 | | NOTFOUND/TRYAGAIN | TRYAGAIN | [3] | |
1291 | | NOTFOUND/TRYAGAIN' | TRYAGAIN' | [3] | |
1292 | | NOTFOUND/NOTFOUND | NOTFOUND | [3] | |
1293 | | NOTFOUND/UNAVAIL | UNAVAIL | [3] | |
1294 | | UNAVAIL/SUCCESS | UNAVAIL | [4] | |
1295 | | UNAVAIL/TRYAGAIN | UNAVAIL | [4] | |
1296 | | UNAVAIL/TRYAGAIN' | UNAVAIL | [4] | |
1297 | | UNAVAIL/NOTFOUND | UNAVAIL | [4] | |
1298 | | UNAVAIL/UNAVAIL | UNAVAIL | [4] | |
1299 | ---------------------------------------------- |
1300 | |
1301 | [1] If the first response is a success we return success. |
1302 | This ignores the state of the second answer and in fact |
1303 | incorrectly sets errno and h_errno to that of the second |
1304 | answer. However because the response is a success we ignore |
1305 | *errnop and *h_errnop (though that means you touched errno on |
1306 | success). We are being conservative here and returning the |
1307 | likely IPv4 response in the first answer as a success. |
1308 | |
1309 | [2] If the first response is a recoverable TRYAGAIN we return |
1310 | that instead of looking at the second response. The |
1311 | expectation here is that we have failed to get an IPv4 response |
1312 | and should retry both queries. |
1313 | |
1314 | [3] If the first response was not a SUCCESS and the second |
1315 | response is not NOTFOUND (had a SUCCESS, need to TRYAGAIN, |
1316 | or failed entirely e.g. TRYAGAIN' and UNAVAIL) then use the |
1317 | result from the second response, otherwise the first responses |
1318 | status is used. Again we have some odd side-effects when the |
1319 | second response is NOTFOUND because we overwrite *errnop and |
1320 | *h_errnop that means that a first answer of NOTFOUND might see |
1321 | its *errnop and *h_errnop values altered. Whether it matters |
1322 | in practice that a first response NOTFOUND has the wrong |
1323 | *errnop and *h_errnop is undecided. |
1324 | |
1325 | [4] If the first response is UNAVAIL we return that instead of |
1326 | looking at the second response. The expectation here is that |
1327 | it will have failed similarly e.g. configuration failure. |
1328 | |
1329 | [5] Testing this code is complicated by the fact that truncated |
1330 | second response buffers might be returned as SUCCESS if the |
1331 | first answer is a SUCCESS. To fix this we add symmetry to |
1332 | TRYAGAIN with the second response. If the second response |
1333 | is a recoverable error we now return TRYAGIN even if the first |
1334 | response was SUCCESS. */ |
1335 | |
1336 | if (anslen1 > 0) |
1337 | status = gaih_getanswer_slice(answer1, anslen1, qname, |
1338 | &pat, &buffer, &buflen, |
1339 | errnop, h_errnop, ttlp, |
1340 | &first); |
1341 | |
1342 | if ((status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND |
1343 | || (status == NSS_STATUS_TRYAGAIN |
1344 | /* We want to look at the second answer in case of an |
1345 | NSS_STATUS_TRYAGAIN only if the error is non-recoverable, i.e. |
1346 | *h_errnop is NO_RECOVERY. If not, and if the failure was due to |
1347 | an insufficient buffer (ERANGE), then we need to drop the results |
1348 | and pass on the NSS_STATUS_TRYAGAIN to the caller so that it can |
1349 | repeat the query with a larger buffer. */ |
1350 | && (*errnop != ERANGE || *h_errnop == NO_RECOVERY))) |
1351 | && answer2 != NULL && anslen2 > 0) |
1352 | { |
1353 | enum nss_status status2 = gaih_getanswer_slice(answer2, anslen2, qname, |
1354 | &pat, &buffer, &buflen, |
1355 | errnop, h_errnop, ttlp, |
1356 | &first); |
1357 | /* Use the second response status in some cases. */ |
1358 | if (status != NSS_STATUS_SUCCESS && status2 != NSS_STATUS_NOTFOUND) |
1359 | status = status2; |
1360 | /* Do not return a truncated second response (unless it was |
1361 | unavoidable e.g. unrecoverable TRYAGAIN). */ |
1362 | if (status == NSS_STATUS_SUCCESS |
1363 | && (status2 == NSS_STATUS_TRYAGAIN |
1364 | && *errnop == ERANGE && *h_errnop != NO_RECOVERY)) |
1365 | status = NSS_STATUS_TRYAGAIN; |
1366 | } |
1367 | |
1368 | return status; |
1369 | } |
1370 | |