1/* Copyright (C) 1998-2016 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
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#include <errno.h>
20#include <resolv.h>
21#include <stdio.h>
22#include <string.h>
23#include <stdint.h>
24#include <arpa/nameser.h>
25#include <not-cancel.h>
26
27#include "nscd-client.h"
28#include "nscd_proto.h"
29
30int __nss_not_use_nscd_hosts;
31
32static int nscd_gethst_r (const char *key, size_t keylen, request_type type,
33 struct hostent *resultbuf, char *buffer,
34 size_t buflen, struct hostent **result,
35 int *h_errnop) internal_function;
36
37
38int
39__nscd_gethostbyname_r (const char *name, struct hostent *resultbuf,
40 char *buffer, size_t buflen, struct hostent **result,
41 int *h_errnop)
42{
43 request_type reqtype;
44
45 reqtype = (_res.options & RES_USE_INET6) ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;
46
47 return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
48 buffer, buflen, result, h_errnop);
49}
50
51
52int
53__nscd_gethostbyname2_r (const char *name, int af, struct hostent *resultbuf,
54 char *buffer, size_t buflen, struct hostent **result,
55 int *h_errnop)
56{
57 request_type reqtype;
58
59 reqtype = af == AF_INET6 ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;
60
61 return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
62 buffer, buflen, result, h_errnop);
63}
64
65
66int
67__nscd_gethostbyaddr_r (const void *addr, socklen_t len, int type,
68 struct hostent *resultbuf, char *buffer, size_t buflen,
69 struct hostent **result, int *h_errnop)
70{
71 request_type reqtype;
72
73 if (!((len == INADDRSZ && type == AF_INET)
74 || (len == IN6ADDRSZ && type == AF_INET6)))
75 /* LEN and TYPE do not match. */
76 return -1;
77
78 reqtype = type == AF_INET6 ? GETHOSTBYADDRv6 : GETHOSTBYADDR;
79
80 return nscd_gethst_r (addr, len, reqtype, resultbuf, buffer, buflen, result,
81 h_errnop);
82}
83
84
85libc_locked_map_ptr (, __hst_map_handle) attribute_hidden;
86/* Note that we only free the structure if necessary. The memory
87 mapping is not removed since it is not visible to the malloc
88 handling. */
89libc_freeres_fn (hst_map_free)
90{
91 if (__hst_map_handle.mapped != NO_MAPPING)
92 {
93 void *p = __hst_map_handle.mapped;
94 __hst_map_handle.mapped = NO_MAPPING;
95 free (p);
96 }
97}
98
99
100uint32_t
101__nscd_get_nl_timestamp (void)
102{
103 uint32_t retval;
104 if (__nss_not_use_nscd_hosts != 0)
105 return 0;
106
107 /* __nscd_get_mapping can change hst_map_handle.mapped to NO_MAPPING.
108 However, __nscd_get_mapping assumes the prior value was not NO_MAPPING.
109 Thus we have to acquire the lock to prevent this thread from changing
110 hst_map_handle.mapped to NO_MAPPING while another thread is inside
111 __nscd_get_mapping. */
112 if (!__nscd_acquire_maplock (&__hst_map_handle))
113 return 0;
114
115 struct mapped_database *map = __hst_map_handle.mapped;
116
117 if (map == NULL
118 || (map != NO_MAPPING
119 && map->head->nscd_certainly_running == 0
120 && map->head->timestamp + MAPPING_TIMEOUT < time (NULL)))
121 map = __nscd_get_mapping (GETFDHST, "hosts", &__hst_map_handle.mapped);
122
123 if (map == NO_MAPPING)
124 retval = 0;
125 else
126 retval = map->head->extra_data[NSCD_HST_IDX_CONF_TIMESTAMP];
127
128 /* Release the lock. */
129 __hst_map_handle.lock = 0;
130
131 return retval;
132}
133
134
135int __nss_have_localdomain attribute_hidden;
136
137static int
138internal_function
139nscd_gethst_r (const char *key, size_t keylen, request_type type,
140 struct hostent *resultbuf, char *buffer, size_t buflen,
141 struct hostent **result, int *h_errnop)
142{
143 if (__glibc_unlikely (__nss_have_localdomain >= 0))
144 {
145 if (__nss_have_localdomain == 0)
146 __nss_have_localdomain = getenv ("LOCALDOMAIN") != NULL ? 1 : -1;
147 if (__nss_have_localdomain > 0)
148 {
149 __nss_not_use_nscd_hosts = 1;
150 return -1;
151 }
152 }
153
154 int gc_cycle;
155 int nretries = 0;
156
157 /* If the mapping is available, try to search there instead of
158 communicating with the nscd. */
159 struct mapped_database *mapped;
160 mapped = __nscd_get_map_ref (GETFDHST, "hosts", &__hst_map_handle,
161 &gc_cycle);
162
163 retry:;
164 const char *h_name = NULL;
165 const uint32_t *aliases_len = NULL;
166 const char *addr_list = NULL;
167 size_t addr_list_len = 0;
168 int retval = -1;
169 const char *recend = (const char *) ~UINTMAX_C (0);
170 int sock = -1;
171 hst_response_header hst_resp;
172 if (mapped != NO_MAPPING)
173 {
174 /* No const qualifier, as it can change during garbage collection. */
175 struct datahead *found = __nscd_cache_search (type, key, keylen, mapped,
176 sizeof hst_resp);
177 if (found != NULL)
178 {
179 h_name = (char *) (&found->data[0].hstdata + 1);
180 hst_resp = found->data[0].hstdata;
181 aliases_len = (uint32_t *) (h_name + hst_resp.h_name_len);
182 addr_list = ((char *) aliases_len
183 + hst_resp.h_aliases_cnt * sizeof (uint32_t));
184 addr_list_len = hst_resp.h_addr_list_cnt * INADDRSZ;
185 recend = (const char *) found->data + found->recsize;
186 /* Now check if we can trust hst_resp fields. If GC is
187 in progress, it can contain anything. */
188 if (mapped->head->gc_cycle != gc_cycle)
189 {
190 retval = -2;
191 goto out;
192 }
193
194#if !_STRING_ARCH_unaligned
195 /* The aliases_len array in the mapped database might very
196 well be unaligned. We will access it word-wise so on
197 platforms which do not tolerate unaligned accesses we
198 need to make an aligned copy. */
199 if (((uintptr_t) aliases_len & (__alignof__ (*aliases_len) - 1))
200 != 0)
201 {
202 uint32_t *tmp = alloca (hst_resp.h_aliases_cnt
203 * sizeof (uint32_t));
204 aliases_len = memcpy (tmp, aliases_len,
205 hst_resp.h_aliases_cnt
206 * sizeof (uint32_t));
207 }
208#endif
209 if (type != GETHOSTBYADDR && type != GETHOSTBYNAME)
210 {
211 if (hst_resp.h_length == INADDRSZ)
212 addr_list += addr_list_len;
213 addr_list_len = hst_resp.h_addr_list_cnt * IN6ADDRSZ;
214 }
215 if (__builtin_expect ((const char *) addr_list + addr_list_len
216 > recend, 0))
217 goto out;
218 }
219 }
220
221 if (h_name == NULL)
222 {
223 sock = __nscd_open_socket (key, keylen, type, &hst_resp,
224 sizeof (hst_resp));
225 if (sock == -1)
226 {
227 __nss_not_use_nscd_hosts = 1;
228 goto out;
229 }
230 }
231
232 /* No value found so far. */
233 *result = NULL;
234
235 if (__glibc_unlikely (hst_resp.found == -1))
236 {
237 /* The daemon does not cache this database. */
238 __nss_not_use_nscd_hosts = 1;
239 goto out_close;
240 }
241
242 if (hst_resp.found == 1)
243 {
244 char *cp = buffer;
245 uintptr_t align1;
246 uintptr_t align2;
247 size_t total_len;
248 ssize_t cnt;
249 char *ignore;
250 int n;
251
252 /* A first check whether the buffer is sufficiently large is possible. */
253 /* Now allocate the buffer the array for the group members. We must
254 align the pointer and the base of the h_addr_list pointers. */
255 align1 = ((__alignof__ (char *) - (cp - ((char *) 0)))
256 & (__alignof__ (char *) - 1));
257 align2 = ((__alignof__ (char *) - ((cp + align1 + hst_resp.h_name_len)
258 - ((char *) 0)))
259 & (__alignof__ (char *) - 1));
260 if (buflen < (align1 + hst_resp.h_name_len + align2
261 + ((hst_resp.h_aliases_cnt + hst_resp.h_addr_list_cnt
262 + 2)
263 * sizeof (char *))
264 + hst_resp.h_addr_list_cnt * (type == AF_INET
265 ? INADDRSZ : IN6ADDRSZ)))
266 {
267 no_room:
268 *h_errnop = NETDB_INTERNAL;
269 __set_errno (ERANGE);
270 retval = ERANGE;
271 goto out_close;
272 }
273 cp += align1;
274
275 /* Prepare the result as far as we can. */
276 resultbuf->h_aliases = (char **) cp;
277 cp += (hst_resp.h_aliases_cnt + 1) * sizeof (char *);
278 resultbuf->h_addr_list = (char **) cp;
279 cp += (hst_resp.h_addr_list_cnt + 1) * sizeof (char *);
280
281 resultbuf->h_name = cp;
282 cp += hst_resp.h_name_len + align2;
283
284 if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
285 {
286 resultbuf->h_addrtype = AF_INET;
287 resultbuf->h_length = INADDRSZ;
288 }
289 else
290 {
291 resultbuf->h_addrtype = AF_INET6;
292 resultbuf->h_length = IN6ADDRSZ;
293 }
294 for (cnt = 0; cnt < hst_resp.h_addr_list_cnt; ++cnt)
295 {
296 resultbuf->h_addr_list[cnt] = cp;
297 cp += resultbuf->h_length;
298 }
299 resultbuf->h_addr_list[cnt] = NULL;
300
301 if (h_name == NULL)
302 {
303 struct iovec vec[4];
304
305 vec[0].iov_base = resultbuf->h_name;
306 vec[0].iov_len = hst_resp.h_name_len;
307 total_len = hst_resp.h_name_len;
308 n = 1;
309
310 if (hst_resp.h_aliases_cnt > 0)
311 {
312 aliases_len = alloca (hst_resp.h_aliases_cnt
313 * sizeof (uint32_t));
314 vec[n].iov_base = (void *) aliases_len;
315 vec[n].iov_len = hst_resp.h_aliases_cnt * sizeof (uint32_t);
316
317 total_len += hst_resp.h_aliases_cnt * sizeof (uint32_t);
318 ++n;
319 }
320
321 if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
322 {
323 vec[n].iov_base = resultbuf->h_addr_list[0];
324 vec[n].iov_len = hst_resp.h_addr_list_cnt * INADDRSZ;
325
326 total_len += hst_resp.h_addr_list_cnt * INADDRSZ;
327
328 ++n;
329 }
330 else
331 {
332 if (hst_resp.h_length == INADDRSZ)
333 {
334 ignore = alloca (hst_resp.h_addr_list_cnt * INADDRSZ);
335 vec[n].iov_base = ignore;
336 vec[n].iov_len = hst_resp.h_addr_list_cnt * INADDRSZ;
337
338 total_len += hst_resp.h_addr_list_cnt * INADDRSZ;
339
340 ++n;
341 }
342
343 vec[n].iov_base = resultbuf->h_addr_list[0];
344 vec[n].iov_len = hst_resp.h_addr_list_cnt * IN6ADDRSZ;
345
346 total_len += hst_resp.h_addr_list_cnt * IN6ADDRSZ;
347
348 ++n;
349 }
350
351 if ((size_t) __readvall (sock, vec, n) != total_len)
352 goto out_close;
353 }
354 else
355 {
356 memcpy (resultbuf->h_name, h_name, hst_resp.h_name_len);
357 memcpy (resultbuf->h_addr_list[0], addr_list, addr_list_len);
358 }
359
360 /* Now we also can read the aliases. */
361 total_len = 0;
362 for (cnt = 0; cnt < hst_resp.h_aliases_cnt; ++cnt)
363 {
364 resultbuf->h_aliases[cnt] = cp;
365 cp += aliases_len[cnt];
366 total_len += aliases_len[cnt];
367 }
368 resultbuf->h_aliases[cnt] = NULL;
369
370 if (__builtin_expect ((const char *) addr_list + addr_list_len
371 + total_len > recend, 0))
372 {
373 /* aliases_len array might contain garbage during nscd GC cycle,
374 retry rather than fail in that case. */
375 if (addr_list != NULL && mapped->head->gc_cycle != gc_cycle)
376 retval = -2;
377 goto out_close;
378 }
379 /* See whether this would exceed the buffer capacity. */
380 if (__glibc_unlikely (cp > buffer + buflen))
381 {
382 /* aliases_len array might contain garbage during nscd GC cycle,
383 retry rather than fail in that case. */
384 if (addr_list != NULL && mapped->head->gc_cycle != gc_cycle)
385 {
386 retval = -2;
387 goto out_close;
388 }
389 goto no_room;
390 }
391
392 /* And finally read the aliases. */
393 if (addr_list == NULL)
394 {
395 if (total_len == 0
396 || ((size_t) __readall (sock, resultbuf->h_aliases[0], total_len)
397 == total_len))
398 {
399 retval = 0;
400 *result = resultbuf;
401 }
402 }
403 else
404 {
405 memcpy (resultbuf->h_aliases[0],
406 (const char *) addr_list + addr_list_len, total_len);
407
408 /* Try to detect corrupt databases. */
409 if (resultbuf->h_name[hst_resp.h_name_len - 1] != '\0'
410 || ({for (cnt = 0; cnt < hst_resp.h_aliases_cnt; ++cnt)
411 if (resultbuf->h_aliases[cnt][aliases_len[cnt] - 1]
412 != '\0')
413 break;
414 cnt < hst_resp.h_aliases_cnt; }))
415 {
416 /* We cannot use the database. */
417 if (mapped->head->gc_cycle != gc_cycle)
418 retval = -2;
419 goto out_close;
420 }
421
422 retval = 0;
423 *result = resultbuf;
424 }
425 }
426 else
427 {
428 /* Store the error number. */
429 *h_errnop = hst_resp.error;
430
431 /* Set errno to 0 to indicate no error, just no found record. */
432 __set_errno (0);
433 /* Even though we have not found anything, the result is zero. */
434 retval = 0;
435 }
436
437 out_close:
438 if (sock != -1)
439 close_not_cancel_no_status (sock);
440 out:
441 if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
442 {
443 /* When we come here this means there has been a GC cycle while we
444 were looking for the data. This means the data might have been
445 inconsistent. Retry if possible. */
446 if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
447 {
448 /* nscd is just running gc now. Disable using the mapping. */
449 if (atomic_decrement_val (&mapped->counter) == 0)
450 __nscd_unmap (mapped);
451 mapped = NO_MAPPING;
452 }
453
454 if (retval != -1)
455 goto retry;
456 }
457
458 return retval;
459}
460