1 /* Cache handling for host lookup.
2 Copyright (C) 2004-2013 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published
8 by the Free Software Foundation; version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, see <http://www.gnu.org/licenses/>. */
28 #include <resolv/res_hconf.h>
33 # include <kernel-features.h>
37 typedef enum nss_status (*nss_gethostbyname4_r
)
38 (const char *name
, struct gaih_addrtuple
**pat
,
39 char *buffer
, size_t buflen
, int *errnop
,
40 int *h_errnop
, int32_t *ttlp
);
41 typedef enum nss_status (*nss_gethostbyname3_r
)
42 (const char *name
, int af
, struct hostent
*host
,
43 char *buffer
, size_t buflen
, int *errnop
,
44 int *h_errnop
, int32_t *, char **);
45 typedef enum nss_status (*nss_getcanonname_r
)
46 (const char *name
, char *buffer
, size_t buflen
, char **result
,
47 int *errnop
, int *h_errnop
);
50 static const ai_response_header notfound
=
52 .version
= NSCD_VERSION
,
62 addhstaiX (struct database_dyn
*db
, int fd
, request_header
*req
,
63 void *key
, uid_t uid
, struct hashentry
*const he
,
66 /* Search for the entry matching the key. Please note that we don't
67 look again in the table whether the dataset is now available. We
68 simply insert it. It does not matter if it is in there twice. The
69 pruning function only will look at the timestamp. */
71 /* We allocate all data in one memory block: the iov vector,
72 the response header and the dataset itself. */
76 ai_response_header resp
;
80 if (__builtin_expect (debug_level
> 0, 0))
83 dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) key
);
85 dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) key
);
88 static service_user
*hosts_database
;
89 service_user
*nip
= NULL
;
95 if (hosts_database
!= NULL
)
101 no_more
= __nss_database_lookup ("hosts", NULL
,
102 "dns [!UNAVAIL=return] files", &nip
);
104 /* Initialize configurations. */
105 if (__builtin_expect (!_res_hconf
.initialized
, 0))
107 if (__res_maybe_init (&_res
, 0) == -1)
110 /* If we are looking for both IPv4 and IPv6 address we don't want
111 the lookup functions to automatically promote IPv4 addresses to
112 IPv6 addresses. Currently this is decided by setting the
113 RES_USE_INET6 bit in _res.options. */
114 int old_res_options
= _res
.options
;
115 _res
.options
&= ~RES_USE_INET6
;
117 size_t tmpbuf6len
= 1024;
118 char *tmpbuf6
= alloca (tmpbuf6len
);
119 size_t tmpbuf4len
= 0;
120 char *tmpbuf4
= NULL
;
121 int32_t ttl
= INT32_MAX
;
123 char *key_copy
= NULL
;
124 bool alloca_used
= false;
125 time_t timeout
= MAX_TIMEOUT_VALUE
;
130 int status
[2] = { NSS_STATUS_UNAVAIL
, NSS_STATUS_UNAVAIL
};
136 nss_gethostbyname4_r fct4
= __nss_lookup_function (nip
,
140 struct gaih_addrtuple atmem
;
141 struct gaih_addrtuple
*at
;
147 status
[1] = DL_CALL_FCT (fct4
, (key
, &at
, tmpbuf6
, tmpbuf6len
,
148 &rc6
, &herrno
, &ttl
));
149 if (rc6
!= ERANGE
|| (herrno
!= NETDB_INTERNAL
150 && herrno
!= TRY_AGAIN
))
152 tmpbuf6
= extend_alloca (tmpbuf6
, tmpbuf6len
, 2 * tmpbuf6len
);
155 if (rc6
!= 0 && herrno
== NETDB_INTERNAL
)
158 if (status
[1] != NSS_STATUS_SUCCESS
)
161 /* We found the data. Count the addresses and the size. */
162 for (const struct gaih_addrtuple
*at2
= at
= &atmem
; at2
!= NULL
;
166 /* We do not handle anything other than IPv4 and IPv6
167 addresses. The getaddrinfo implementation does not
168 either so it is not worth trying to do more. */
169 if (at2
->family
== AF_INET
)
170 addrslen
+= INADDRSZ
;
171 else if (at2
->family
== AF_INET6
)
172 addrslen
+= IN6ADDRSZ
;
175 canonlen
= strlen (canon
) + 1;
177 total
= sizeof (*dataset
) + naddrs
+ addrslen
+ canonlen
;
179 /* Now we can allocate the data structure. If the TTL of the
180 entry is reported as zero do not cache the entry at all. */
181 if (ttl
!= 0 && he
== NULL
)
182 dataset
= (struct dataset
*) mempool_alloc (db
, total
187 /* We cannot permanently add the result in the moment. But
188 we can provide the result as is. Store the data in some
190 dataset
= (struct dataset
*) alloca (total
+ req
->key_len
);
192 /* We cannot add this record to the permanent database. */
196 /* Fill in the address and address families. */
197 char *addrs
= dataset
->strdata
;
198 uint8_t *family
= (uint8_t *) (addrs
+ addrslen
);
200 for (const struct gaih_addrtuple
*at2
= at
; at2
!= NULL
;
203 *family
++ = at2
->family
;
204 if (at2
->family
== AF_INET
)
205 addrs
= mempcpy (addrs
, at2
->addr
, INADDRSZ
);
206 else if (at2
->family
== AF_INET6
)
207 addrs
= mempcpy (addrs
, at2
->addr
, IN6ADDRSZ
);
214 /* Prefer the function which also returns the TTL and
216 nss_gethostbyname3_r fct
= __nss_lookup_function (nip
,
219 fct
= __nss_lookup_function (nip
, "gethostbyname2_r");
224 struct hostent th
[2];
226 /* Collect IPv6 information first. */
230 status
[0] = DL_CALL_FCT (fct
, (key
, AF_INET6
, &th
[0], tmpbuf6
,
231 tmpbuf6len
, &rc6
, &herrno
, &ttl
,
233 if (rc6
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
235 tmpbuf6
= extend_alloca (tmpbuf6
, tmpbuf6len
, 2 * tmpbuf6len
);
238 if (rc6
!= 0 && herrno
== NETDB_INTERNAL
)
241 /* If the IPv6 lookup has been successful do not use the
242 buffer used in that lookup, use a new one. */
243 if (status
[0] == NSS_STATUS_SUCCESS
&& rc6
== 0)
246 tmpbuf4
= alloca (tmpbuf4len
);
250 tmpbuf4len
= tmpbuf6len
;
254 /* Next collect IPv4 information. */
258 status
[1] = DL_CALL_FCT (fct
, (key
, AF_INET
, &th
[1], tmpbuf4
,
259 tmpbuf4len
, &rc4
, &herrno
,
260 ttl
== INT32_MAX
? &ttl
: NULL
,
261 canon
== NULL
? &canon
: NULL
));
262 if (rc4
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
264 tmpbuf4
= extend_alloca (tmpbuf4
, tmpbuf4len
, 2 * tmpbuf4len
);
267 if (rc4
!= 0 && herrno
== NETDB_INTERNAL
)
270 if (status
[0] != NSS_STATUS_SUCCESS
271 && status
[1] != NSS_STATUS_SUCCESS
)
274 /* We found the data. Count the addresses and the size. */
275 for (int j
= 0; j
< 2; ++j
)
276 if (status
[j
] == NSS_STATUS_SUCCESS
)
277 for (int i
= 0; th
[j
].h_addr_list
[i
] != NULL
; ++i
)
280 addrslen
+= th
[j
].h_length
;
285 /* Determine the canonical name. */
286 nss_getcanonname_r cfct
;
287 cfct
= __nss_lookup_function (nip
, "getcanonname_r");
290 const size_t max_fqdn_len
= 256;
291 char *buf
= alloca (max_fqdn_len
);
295 if (DL_CALL_FCT (cfct
, (key
, buf
, max_fqdn_len
, &s
,
297 == NSS_STATUS_SUCCESS
)
300 /* Set to name now to avoid using gethostbyaddr. */
305 struct hostent
*hstent
= NULL
;
307 struct hostent hstent_mem
;
312 if (status
[1] == NSS_STATUS_SUCCESS
)
314 addr
= th
[1].h_addr_list
[0];
315 addrlen
= sizeof (struct in_addr
);
316 addrfamily
= AF_INET
;
320 addr
= th
[0].h_addr_list
[0];
321 addrlen
= sizeof (struct in6_addr
);
322 addrfamily
= AF_INET6
;
325 size_t tmpbuflen
= 512;
326 char *tmpbuf
= alloca (tmpbuflen
);
330 rc
= __gethostbyaddr2_r (addr
, addrlen
, addrfamily
,
331 &hstent_mem
, tmpbuf
, tmpbuflen
,
332 &hstent
, &herrno
, NULL
);
333 if (rc
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
335 tmpbuf
= extend_alloca (tmpbuf
, tmpbuflen
,
342 canon
= hstent
->h_name
;
349 canonlen
= canon
== NULL
? 0 : (strlen (canon
) + 1);
351 total
= sizeof (*dataset
) + naddrs
+ addrslen
+ canonlen
;
354 /* Now we can allocate the data structure. If the TTL of the
355 entry is reported as zero do not cache the entry at all. */
356 if (ttl
!= 0 && he
== NULL
)
357 dataset
= (struct dataset
*) mempool_alloc (db
, total
362 /* We cannot permanently add the result in the moment. But
363 we can provide the result as is. Store the data in some
365 dataset
= (struct dataset
*) alloca (total
+ req
->key_len
);
367 /* We cannot add this record to the permanent database. */
371 /* Fill in the address and address families. */
372 char *addrs
= dataset
->strdata
;
373 uint8_t *family
= (uint8_t *) (addrs
+ addrslen
);
375 for (int j
= 0; j
< 2; ++j
)
376 if (status
[j
] == NSS_STATUS_SUCCESS
)
377 for (int i
= 0; th
[j
].h_addr_list
[i
] != NULL
; ++i
)
379 addrs
= mempcpy (addrs
, th
[j
].h_addr_list
[i
],
381 *family
++ = th
[j
].h_addrtype
;
387 /* Fill in the rest of the dataset. */
388 dataset
->head
.allocsize
= total
+ req
->key_len
;
389 dataset
->head
.recsize
= total
- offsetof (struct dataset
, resp
);
390 dataset
->head
.notfound
= false;
391 dataset
->head
.nreloads
= he
== NULL
? 0 : (dh
->nreloads
+ 1);
392 dataset
->head
.usable
= true;
394 /* Compute the timeout time. */
395 dataset
->head
.ttl
= ttl
== INT32_MAX
? db
->postimeout
: ttl
;
396 timeout
= dataset
->head
.timeout
= time (NULL
) + dataset
->head
.ttl
;
398 dataset
->resp
.version
= NSCD_VERSION
;
399 dataset
->resp
.found
= 1;
400 dataset
->resp
.naddrs
= naddrs
;
401 dataset
->resp
.addrslen
= addrslen
;
402 dataset
->resp
.canonlen
= canonlen
;
403 dataset
->resp
.error
= NETDB_SUCCESS
;
406 cp
= mempcpy (cp
, canon
, canonlen
);
408 key_copy
= memcpy (cp
, key
, req
->key_len
);
410 assert (cp
== (char *) dataset
+ total
);
412 /* Now we can determine whether on refill we have to create a
413 new record or not. */
418 if (total
+ req
->key_len
== dh
->allocsize
419 && total
- offsetof (struct dataset
, resp
) == dh
->recsize
420 && memcmp (&dataset
->resp
, dh
->data
,
421 dh
->allocsize
- offsetof (struct dataset
,
424 /* The data has not changed. We will just bump the
425 timeout value. Note that the new record has been
426 allocated on the stack and need not be freed. */
427 dh
->timeout
= dataset
->head
.timeout
;
428 dh
->ttl
= dataset
->head
.ttl
;
433 /* We have to create a new record. Just allocate
434 appropriate memory and copy it. */
436 = (struct dataset
*) mempool_alloc (db
, total
+ req
->key_len
,
438 if (__builtin_expect (newp
!= NULL
, 1))
440 /* Adjust pointer into the memory block. */
441 key_copy
= (char *) newp
+ (key_copy
- (char *) dataset
);
443 dataset
= memcpy (newp
, dataset
, total
+ req
->key_len
);
447 /* Mark the old record as obsolete. */
453 /* We write the dataset before inserting it to the database
454 since while inserting this thread might block and so
455 would unnecessarily let the receiver wait. */
459 if (__builtin_expect (db
->mmap_used
, 1) && !alloca_used
)
461 assert (db
->wr_fd
!= -1);
462 assert ((char *) &dataset
->resp
> (char *) db
->data
);
463 assert ((char *) dataset
- (char *) db
->head
+ total
464 <= (sizeof (struct database_pers_head
)
465 + db
->head
->module
* sizeof (ref_t
)
466 + db
->head
->data_size
));
467 # ifndef __ASSUME_SENDFILE
471 sendfileall (fd
, db
->wr_fd
, (char *) &dataset
->resp
472 - (char *) db
->head
, dataset
->head
.recsize
);
473 # ifndef __ASSUME_SENDFILE
474 if (written
== -1 && errno
== ENOSYS
)
479 # ifndef __ASSUME_SENDFILE
483 writeall (fd
, &dataset
->resp
, dataset
->head
.recsize
);
489 if (nss_next_action (nip
, status
[1]) == NSS_ACTION_RETURN
)
492 if (nip
->next
== NULL
)
498 /* No result found. Create a negative result record. */
499 if (he
!= NULL
&& rc4
== EAGAIN
)
501 /* If we have an old record available but cannot find one now
502 because the service is not available we keep the old record
503 and make sure it does not get removed. */
504 if (reload_count
!= UINT_MAX
&& dh
->nreloads
== reload_count
)
505 /* Do not reset the value if we never not reload the record. */
506 dh
->nreloads
= reload_count
- 1;
508 /* Reload with the same time-to-live value. */
509 timeout
= dh
->timeout
= time (NULL
) + dh
->ttl
;
513 /* We have no data. This means we send the standard reply for
515 total
= sizeof (notfound
);
518 TEMP_FAILURE_RETRY (send (fd
, ¬found
, total
, MSG_NOSIGNAL
));
520 /* If we have a transient error or cannot permanently store the
522 if (rc4
== EAGAIN
|| __builtin_expect (db
->negtimeout
== 0, 0))
524 /* Mark the old entry as obsolete. */
529 else if ((dataset
= mempool_alloc (db
, (sizeof (struct dataset
)
530 + req
->key_len
), 1)) != NULL
)
532 dataset
->head
.allocsize
= sizeof (struct dataset
) + req
->key_len
;
533 dataset
->head
.recsize
= total
;
534 dataset
->head
.notfound
= true;
535 dataset
->head
.nreloads
= 0;
536 dataset
->head
.usable
= true;
538 /* Compute the timeout time. */
539 timeout
= dataset
->head
.timeout
= time (NULL
) + db
->negtimeout
;
540 dataset
->head
.ttl
= db
->negtimeout
;
542 /* This is the reply. */
543 memcpy (&dataset
->resp
, ¬found
, total
);
545 /* Copy the key data. */
546 key_copy
= memcpy (dataset
->strdata
, key
, req
->key_len
);
551 _res
.options
|= old_res_options
& RES_USE_INET6
;
553 if (dataset
!= NULL
&& !alloca_used
)
555 /* If necessary, we also propagate the data to disk. */
559 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
560 msync ((void *) pval
,
561 ((uintptr_t) dataset
& pagesize_m1
) + total
+ req
->key_len
,
565 (void) cache_add (req
->type
, key_copy
, req
->key_len
, &dataset
->head
,
566 true, db
, uid
, he
== NULL
);
568 pthread_rwlock_unlock (&db
->lock
);
570 /* Mark the old entry as obsolete. */
580 addhstai (struct database_dyn
*db
, int fd
, request_header
*req
, void *key
,
583 addhstaiX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
588 readdhstai (struct database_dyn
*db
, struct hashentry
*he
, struct datahead
*dh
)
596 return addhstaiX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);