1 /* Cache handling for host lookup.
2 Copyright (C) 2004, 2005, 2006, 2007 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, write to the Free Software Foundation,
18 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
32 # include <kernel-features.h>
36 typedef enum nss_status (*nss_gethostbyname3_r
)
37 (const char *name
, int af
, struct hostent
*host
,
38 char *buffer
, size_t buflen
, int *errnop
,
39 int *h_errnop
, int32_t *, char **);
40 typedef enum nss_status (*nss_getcanonname_r
)
41 (const char *name
, char *buffer
, size_t buflen
, char **result
,
42 int *errnop
, int *h_errnop
);
45 static const ai_response_header notfound
=
47 .version
= NSCD_VERSION
,
57 addhstaiX (struct database_dyn
*db
, int fd
, request_header
*req
,
58 void *key
, uid_t uid
, struct hashentry
*he
, struct datahead
*dh
)
60 /* Search for the entry matching the key. Please note that we don't
61 look again in the table whether the dataset is now available. We
62 simply insert it. It does not matter if it is in there twice. The
63 pruning function only will look at the timestamp. */
65 /* We allocate all data in one memory block: the iov vector,
66 the response header and the dataset itself. */
70 ai_response_header resp
;
74 if (__builtin_expect (debug_level
> 0, 0))
77 dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) key
);
79 dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) key
);
82 static service_user
*hosts_database
;
83 service_user
*nip
= NULL
;
89 if (hosts_database
!= NULL
)
95 no_more
= __nss_database_lookup ("hosts", NULL
,
96 "dns [!UNAVAIL=return] files", &nip
);
98 if (__res_maybe_init (&_res
, 0) == -1)
101 /* If we are looking for both IPv4 and IPv6 address we don't want
102 the lookup functions to automatically promote IPv4 addresses to
103 IPv6 addresses. Currently this is decided by setting the
104 RES_USE_INET6 bit in _res.options. */
105 int old_res_options
= _res
.options
;
106 _res
.options
&= ~RES_USE_INET6
;
108 size_t tmpbuf6len
= 512;
109 char *tmpbuf6
= alloca (tmpbuf6len
);
110 size_t tmpbuf4len
= 0;
111 char *tmpbuf4
= NULL
;
113 int32_t ttl
= INT32_MAX
;
115 char *key_copy
= NULL
;
116 bool alloca_used
= false;
120 int status
[2] = { NSS_STATUS_UNAVAIL
, NSS_STATUS_UNAVAIL
};
122 /* Prefer the function which also returns the TTL and canonical name. */
123 nss_gethostbyname3_r fct
= __nss_lookup_function (nip
,
126 fct
= __nss_lookup_function (nip
, "gethostbyname2_r");
130 struct hostent th
[2];
132 /* Collect IPv6 information first. */
136 status
[0] = DL_CALL_FCT (fct
, (key
, AF_INET6
, &th
[0], tmpbuf6
,
137 tmpbuf6len
, &rc6
, &herrno
,
139 if (rc6
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
141 tmpbuf6
= extend_alloca (tmpbuf6
, tmpbuf6len
, 2 * tmpbuf6len
);
144 if (rc6
!= 0 && herrno
== NETDB_INTERNAL
)
147 /* If the IPv6 lookup has been successful do not use the
148 buffer used in that lookup, use a new one. */
149 if (status
[0] == NSS_STATUS_SUCCESS
&& rc6
== 0)
152 tmpbuf4
= alloca (tmpbuf4len
);
156 tmpbuf4len
= tmpbuf6len
;
160 /* Next collect IPv4 information first. */
164 status
[1] = DL_CALL_FCT (fct
, (key
, AF_INET
, &th
[1], tmpbuf4
,
165 tmpbuf4len
, &rc4
, &herrno
,
166 ttl
== INT32_MAX
? &ttl
: NULL
,
167 canon
== NULL
? &canon
: NULL
));
168 if (rc4
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
170 tmpbuf4
= extend_alloca (tmpbuf4
, tmpbuf4len
, 2 * tmpbuf4len
);
173 if (rc4
!= 0 || herrno
== NETDB_INTERNAL
)
176 if (status
[0] == NSS_STATUS_SUCCESS
177 || status
[1] == NSS_STATUS_SUCCESS
)
179 /* We found the data. Count the addresses and the size. */
182 for (int j
= 0; j
< 2; ++j
)
183 if (status
[j
] == NSS_STATUS_SUCCESS
)
184 for (int i
= 0; th
[j
].h_addr_list
[i
] != NULL
; ++i
)
187 addrslen
+= th
[j
].h_length
;
192 /* Determine the canonical name. */
193 nss_getcanonname_r cfct
;
194 cfct
= __nss_lookup_function (nip
, "getcanonname_r");
197 const size_t max_fqdn_len
= 256;
198 char *buf
= alloca (max_fqdn_len
);
202 if (DL_CALL_FCT (cfct
, (key
, buf
, max_fqdn_len
, &s
, &rc
,
203 &herrno
)) == NSS_STATUS_SUCCESS
)
206 /* Set to name now to avoid using gethostbyaddr. */
211 struct hostent
*he
= NULL
;
213 struct hostent he_mem
;
218 if (status
[1] == NSS_STATUS_SUCCESS
)
220 addr
= th
[1].h_addr_list
[0];
221 addrlen
= sizeof (struct in_addr
);
222 addrfamily
= AF_INET
;
226 addr
= th
[0].h_addr_list
[0];
227 addrlen
= sizeof (struct in6_addr
);
228 addrfamily
= AF_INET6
;
231 size_t tmpbuflen
= 512;
232 char *tmpbuf
= alloca (tmpbuflen
);
236 rc
= __gethostbyaddr2_r (addr
, addrlen
, addrfamily
,
237 &he_mem
, tmpbuf
, tmpbuflen
,
239 if (rc
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
241 tmpbuf
= extend_alloca (tmpbuf
, tmpbuflen
,
254 size_t canonlen
= canon
== NULL
? 0 : (strlen (canon
) + 1);
256 total
= sizeof (*dataset
) + naddrs
+ addrslen
+ canonlen
;
258 /* Now we can allocate the data structure. If the TTL
259 of the entry is reported as zero do not cache the
261 if (ttl
!= 0 && he
== NULL
)
263 dataset
= (struct dataset
*) mempool_alloc (db
,
267 ++db
->head
->addfailed
;
272 /* We cannot permanently add the result in the moment. But
273 we can provide the result as is. Store the data in some
275 dataset
= (struct dataset
*) alloca (total
+ req
->key_len
);
277 /* We cannot add this record to the permanent database. */
281 dataset
->head
.allocsize
= total
+ req
->key_len
;
282 dataset
->head
.recsize
= total
- offsetof (struct dataset
, resp
);
283 dataset
->head
.notfound
= false;
284 dataset
->head
.nreloads
= he
== NULL
? 0 : (dh
->nreloads
+ 1);
285 dataset
->head
.usable
= true;
287 /* Compute the timeout time. */
288 dataset
->head
.timeout
= time (NULL
) + (ttl
== INT32_MAX
289 ? db
->postimeout
: ttl
);
291 dataset
->resp
.version
= NSCD_VERSION
;
292 dataset
->resp
.found
= 1;
293 dataset
->resp
.naddrs
= naddrs
;
294 dataset
->resp
.addrslen
= addrslen
;
295 dataset
->resp
.canonlen
= canonlen
;
296 dataset
->resp
.error
= NETDB_SUCCESS
;
298 char *addrs
= (char *) (&dataset
->resp
+ 1);
299 uint8_t *family
= (uint8_t *) (addrs
+ addrslen
);
301 for (int j
= 0; j
< 2; ++j
)
302 if (status
[j
] == NSS_STATUS_SUCCESS
)
303 for (int i
= 0; th
[j
].h_addr_list
[i
] != NULL
; ++i
)
305 addrs
= mempcpy (addrs
, th
[j
].h_addr_list
[i
],
307 *family
++ = th
[j
].h_addrtype
;
312 cp
= mempcpy (cp
, canon
, canonlen
);
314 key_copy
= memcpy (cp
, key
, req
->key_len
);
316 /* Now we can determine whether on refill we have to
317 create a new record or not. */
322 if (total
+ req
->key_len
== dh
->allocsize
323 && total
- offsetof (struct dataset
, resp
) == dh
->recsize
324 && memcmp (&dataset
->resp
, dh
->data
,
326 - offsetof (struct dataset
, resp
)) == 0)
328 /* The data has not changed. We will just bump the
329 timeout value. Note that the new record has been
330 allocated on the stack and need not be freed. */
331 dh
->timeout
= dataset
->head
.timeout
;
336 /* We have to create a new record. Just allocate
337 appropriate memory and copy it. */
339 = (struct dataset
*) mempool_alloc (db
,
344 /* Adjust pointer into the memory block. */
345 key_copy
= (char *) newp
+ (key_copy
348 dataset
= memcpy (newp
, dataset
,
349 total
+ req
->key_len
);
353 /* Mark the old record as obsolete. */
359 /* We write the dataset before inserting it to the
360 database since while inserting this thread might
361 block and so would unnecessarily let the receiver
366 if (__builtin_expect (db
->mmap_used
, 1) && !alloca_used
)
368 assert (db
->wr_fd
!= -1);
369 assert ((char *) &dataset
->resp
> (char *) db
->data
);
370 assert ((char *) &dataset
->resp
- (char *) db
->head
372 <= (sizeof (struct database_pers_head
)
373 + db
->head
->module
* sizeof (ref_t
)
374 + db
->head
->data_size
));
376 written
= sendfileall (fd
, db
->wr_fd
,
377 (char *) &dataset
->resp
378 - (char *) db
->head
, total
);
379 # ifndef __ASSUME_SENDFILE
380 if (written
== -1 && errno
== ENOSYS
)
385 # ifndef __ASSUME_SENDFILE
389 writeall (fd
, &dataset
->resp
, total
);
397 if (nss_next_action (nip
, status
[1]) == NSS_ACTION_RETURN
)
400 if (nip
->next
== NULL
)
406 /* No result found. Create a negative result record. */
407 if (he
!= NULL
&& rc4
== EAGAIN
)
409 /* If we have an old record available but cannot find one now
410 because the service is not available we keep the old record
411 and make sure it does not get removed. */
412 if (reload_count
!= UINT_MAX
&& dh
->nreloads
== reload_count
)
413 /* Do not reset the value if we never not reload the record. */
414 dh
->nreloads
= reload_count
- 1;
418 /* We have no data. This means we send the standard reply for
420 total
= sizeof (notfound
);
423 TEMP_FAILURE_RETRY (send (fd
, ¬found
, total
, MSG_NOSIGNAL
));
425 dataset
= mempool_alloc (db
, sizeof (struct dataset
) + req
->key_len
);
426 /* If we cannot permanently store the result, so be it. */
429 dataset
->head
.allocsize
= sizeof (struct dataset
) + req
->key_len
;
430 dataset
->head
.recsize
= total
;
431 dataset
->head
.notfound
= true;
432 dataset
->head
.nreloads
= 0;
433 dataset
->head
.usable
= true;
435 /* Compute the timeout time. */
436 dataset
->head
.timeout
= time (NULL
) + db
->negtimeout
;
438 /* This is the reply. */
439 memcpy (&dataset
->resp
, ¬found
, total
);
441 /* Copy the key data. */
442 key_copy
= memcpy (dataset
->strdata
, key
, req
->key_len
);
445 ++db
->head
->addfailed
;
449 _res
.options
= old_res_options
;
451 if (dataset
!= NULL
&& !alloca_used
)
453 /* If necessary, we also propagate the data to disk. */
457 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
458 msync ((void *) pval
,
459 ((uintptr_t) dataset
& pagesize_m1
) + total
+ req
->key_len
,
463 /* Now get the lock to safely insert the records. */
464 pthread_rwlock_rdlock (&db
->lock
);
466 if (cache_add (req
->type
, key_copy
, req
->key_len
, &dataset
->head
, true,
468 /* Ensure the data can be recovered. */
469 dataset
->head
.usable
= false;
471 pthread_rwlock_unlock (&db
->lock
);
473 /* Mark the old entry as obsolete. */
481 addhstai (struct database_dyn
*db
, int fd
, request_header
*req
, void *key
,
484 addhstaiX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
489 readdhstai (struct database_dyn
*db
, struct hashentry
*he
, struct datahead
*dh
)
497 addhstaiX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);