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 version 2 as
8 published by the Free Software Foundation.
10 This program 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
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program; if not, write to the Free Software Foundation,
17 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
31 # include <kernel-features.h>
35 typedef enum nss_status (*nss_gethostbyname3_r
)
36 (const char *name
, int af
, struct hostent
*host
,
37 char *buffer
, size_t buflen
, int *errnop
,
38 int *h_errnop
, int32_t *, char **);
39 typedef enum nss_status (*nss_getcanonname_r
)
40 (const char *name
, char *buffer
, size_t buflen
, char **result
,
41 int *errnop
, int *h_errnop
);
44 static const ai_response_header notfound
=
46 .version
= NSCD_VERSION
,
56 addhstaiX (struct database_dyn
*db
, int fd
, request_header
*req
,
57 void *key
, uid_t uid
, struct hashentry
*he
, struct datahead
*dh
)
59 /* Search for the entry matching the key. Please note that we don't
60 look again in the table whether the dataset is now available. We
61 simply insert it. It does not matter if it is in there twice. The
62 pruning function only will look at the timestamp. */
64 /* We allocate all data in one memory block: the iov vector,
65 the response header and the dataset itself. */
69 ai_response_header resp
;
73 if (__builtin_expect (debug_level
> 0, 0))
76 dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) key
);
78 dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) key
);
81 static service_user
*hosts_database
;
82 service_user
*nip
= NULL
;
88 if (hosts_database
!= NULL
)
94 no_more
= __nss_database_lookup ("hosts", NULL
,
95 "dns [!UNAVAIL=return] files", &nip
);
97 if (__res_maybe_init (&_res
, 0) == -1)
100 /* If we are looking for both IPv4 and IPv6 address we don't want
101 the lookup functions to automatically promote IPv4 addresses to
102 IPv6 addresses. Currently this is decided by setting the
103 RES_USE_INET6 bit in _res.options. */
104 int old_res_options
= _res
.options
;
105 _res
.options
&= ~RES_USE_INET6
;
107 size_t tmpbuf6len
= 512;
108 char *tmpbuf6
= alloca (tmpbuf6len
);
109 size_t tmpbuf4len
= 0;
110 char *tmpbuf4
= NULL
;
112 int32_t ttl
= UINT32_MAX
;
114 char *key_copy
= NULL
;
115 bool alloca_used
= false;
119 int status
[2] = { NSS_STATUS_UNAVAIL
, NSS_STATUS_UNAVAIL
};
121 /* Prefer the function which also returns the TTL and canonical name. */
122 nss_gethostbyname3_r fct
= __nss_lookup_function (nip
,
125 fct
= __nss_lookup_function (nip
, "gethostbyname2_r");
129 struct hostent th
[2];
131 /* Collect IPv6 information first. */
135 status
[0] = DL_CALL_FCT (fct
, (key
, AF_INET6
, &th
[0], tmpbuf6
,
136 tmpbuf6len
, &rc6
, &herrno
,
138 if (rc6
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
140 tmpbuf6
= extend_alloca (tmpbuf6
, tmpbuf6len
, 2 * tmpbuf6len
);
143 if (rc6
!= 0 && herrno
== NETDB_INTERNAL
)
146 /* If the IPv6 lookup has been successful do not use the
147 buffer used in that lookup, use a new one. */
148 if (status
[0] == NSS_STATUS_SUCCESS
&& rc6
== 0)
151 tmpbuf4
= alloca (tmpbuf4len
);
155 tmpbuf4len
= tmpbuf6len
;
159 /* Next collect IPv4 information first. */
163 status
[1] = DL_CALL_FCT (fct
, (key
, AF_INET
, &th
[1], tmpbuf4
,
164 tmpbuf4len
, &rc4
, &herrno
,
165 ttl
== UINT32_MAX
? &ttl
: NULL
,
166 canon
== NULL
? &canon
: NULL
));
167 if (rc4
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
169 tmpbuf4
= extend_alloca (tmpbuf4
, tmpbuf4len
, 2 * tmpbuf4len
);
172 if (rc4
!= 0 || herrno
== NETDB_INTERNAL
)
175 if (status
[0] == NSS_STATUS_SUCCESS
176 || status
[1] == NSS_STATUS_SUCCESS
)
178 /* We found the data. Count the addresses and the size. */
181 for (int j
= 0; j
< 2; ++j
)
182 if (status
[j
] == NSS_STATUS_SUCCESS
)
183 for (int i
= 0; th
[j
].h_addr_list
[i
] != NULL
; ++i
)
186 addrslen
+= th
[j
].h_length
;
191 /* Determine the canonical name. */
192 nss_getcanonname_r cfct
;
193 cfct
= __nss_lookup_function (nip
, "getcanonname_r");
196 const size_t max_fqdn_len
= 256;
197 char *buf
= alloca (max_fqdn_len
);
201 if (DL_CALL_FCT (cfct
, (key
, buf
, max_fqdn_len
, &s
, &rc
,
202 &herrno
)) == NSS_STATUS_SUCCESS
)
205 /* Set to name now to avoid using gethostbyaddr. */
210 struct hostent
*he
= NULL
;
212 struct hostent he_mem
;
217 if (status
[1] == NSS_STATUS_SUCCESS
)
219 addr
= th
[1].h_addr_list
[0];
220 addrlen
= sizeof (struct in_addr
);
221 addrfamily
= AF_INET
;
225 addr
= th
[0].h_addr_list
[0];
226 addrlen
= sizeof (struct in6_addr
);
227 addrfamily
= AF_INET6
;
230 size_t tmpbuflen
= 512;
231 char *tmpbuf
= alloca (tmpbuflen
);
235 rc
= __gethostbyaddr_r (addr
, addrlen
, addrfamily
,
236 &he_mem
, tmpbuf
, tmpbuflen
,
238 if (rc
!= ERANGE
|| herrno
!= NETDB_INTERNAL
)
240 tmpbuf
= extend_alloca (tmpbuf
, tmpbuflen
,
253 size_t canonlen
= canon
== NULL
? 0 : (strlen (canon
) + 1);
255 total
= sizeof (*dataset
) + naddrs
+ addrslen
+ canonlen
;
257 /* Now we can allocate the data structure. If the TTL
258 of the entry is reported as zero do not cache the
260 if (ttl
!= 0 && he
== NULL
)
262 dataset
= (struct dataset
*) mempool_alloc (db
,
266 ++db
->head
->addfailed
;
271 /* We cannot permanently add the result in the moment. But
272 we can provide the result as is. Store the data in some
274 dataset
= (struct dataset
*) alloca (total
+ req
->key_len
);
276 /* We cannot add this record to the permanent database. */
280 dataset
->head
.allocsize
= total
+ req
->key_len
;
281 dataset
->head
.recsize
= total
- offsetof (struct dataset
, resp
);
282 dataset
->head
.notfound
= false;
283 dataset
->head
.nreloads
= he
== NULL
? 0 : (dh
->nreloads
+ 1);
284 dataset
->head
.usable
= true;
286 /* Compute the timeout time. */
287 dataset
->head
.timeout
= time (NULL
) + MIN (db
->postimeout
, ttl
);
289 dataset
->resp
.version
= NSCD_VERSION
;
290 dataset
->resp
.found
= 1;
291 dataset
->resp
.naddrs
= naddrs
;
292 dataset
->resp
.addrslen
= addrslen
;
293 dataset
->resp
.canonlen
= canonlen
;
294 dataset
->resp
.error
= NETDB_SUCCESS
;
296 char *addrs
= (char *) (&dataset
->resp
+ 1);
297 uint8_t *family
= (uint8_t *) (addrs
+ addrslen
);
299 for (int j
= 0; j
< 2; ++j
)
300 if (status
[j
] == NSS_STATUS_SUCCESS
)
301 for (int i
= 0; th
[j
].h_addr_list
[i
] != NULL
; ++i
)
303 addrs
= mempcpy (addrs
, th
[j
].h_addr_list
[i
],
305 *family
++ = th
[j
].h_addrtype
;
310 cp
= mempcpy (cp
, canon
, canonlen
);
312 key_copy
= memcpy (cp
, key
, req
->key_len
);
314 /* Now we can determine whether on refill we have to
315 create a new record or not. */
320 if (total
+ req
->key_len
== dh
->allocsize
321 && total
- offsetof (struct dataset
, resp
) == dh
->recsize
322 && memcmp (&dataset
->resp
, dh
->data
,
324 - offsetof (struct dataset
, resp
)) == 0)
326 /* The data has not changed. We will just bump the
327 timeout value. Note that the new record has been
328 allocated on the stack and need not be freed. */
329 dh
->timeout
= dataset
->head
.timeout
;
334 /* We have to create a new record. Just allocate
335 appropriate memory and copy it. */
337 = (struct dataset
*) mempool_alloc (db
,
342 /* Adjust pointer into the memory block. */
343 key_copy
= (char *) newp
+ (key_copy
346 dataset
= memcpy (newp
, dataset
,
347 total
+ req
->key_len
);
351 /* Mark the old record as obsolete. */
357 /* We write the dataset before inserting it to the
358 database since while inserting this thread might
359 block and so would unnecessarily let the receiver
364 if (__builtin_expect (db
->mmap_used
, 1) && !alloca_used
)
366 assert (db
->wr_fd
!= -1);
367 assert ((char *) &dataset
->resp
> (char *) db
->data
);
368 assert ((char *) &dataset
->resp
- (char *) db
->head
370 <= (sizeof (struct database_pers_head
)
371 + db
->head
->module
* sizeof (ref_t
)
372 + db
->head
->data_size
));
374 written
= sendfileall (fd
, db
->wr_fd
,
375 (char *) &dataset
->resp
376 - (char *) db
->head
, total
);
377 # ifndef __ASSUME_SENDFILE
378 if (written
== -1 && errno
== ENOSYS
)
383 # ifndef __ASSUME_SENDFILE
387 writeall (fd
, &dataset
->resp
, total
);
395 if (nss_next_action (nip
, status
[1]) == NSS_ACTION_RETURN
)
398 if (nip
->next
== NULL
)
404 /* No result found. Create a negative result record. */
405 if (he
!= NULL
&& rc4
== EAGAIN
)
407 /* If we have an old record available but cannot find one now
408 because the service is not available we keep the old record
409 and make sure it does not get removed. */
410 if (reload_count
!= UINT_MAX
&& dh
->nreloads
== reload_count
)
411 /* Do not reset the value if we never not reload the record. */
412 dh
->nreloads
= reload_count
- 1;
416 /* We have no data. This means we send the standard reply for
418 total
= sizeof (notfound
);
421 TEMP_FAILURE_RETRY (send (fd
, ¬found
, total
, MSG_NOSIGNAL
));
423 dataset
= mempool_alloc (db
, sizeof (struct dataset
) + req
->key_len
);
424 /* If we cannot permanently store the result, so be it. */
427 dataset
->head
.allocsize
= sizeof (struct dataset
) + req
->key_len
;
428 dataset
->head
.recsize
= total
;
429 dataset
->head
.notfound
= true;
430 dataset
->head
.nreloads
= 0;
431 dataset
->head
.usable
= true;
433 /* Compute the timeout time. */
434 dataset
->head
.timeout
= time (NULL
) + db
->negtimeout
;
436 /* This is the reply. */
437 memcpy (&dataset
->resp
, ¬found
, total
);
439 /* Copy the key data. */
440 key_copy
= memcpy (dataset
->strdata
, key
, req
->key_len
);
443 ++db
->head
->addfailed
;
447 _res
.options
= old_res_options
;
449 if (dataset
!= NULL
&& !alloca_used
)
451 /* If necessary, we also propagate the data to disk. */
455 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
456 msync ((void *) pval
,
457 ((uintptr_t) dataset
& pagesize_m1
) + total
+ req
->key_len
,
461 /* Now get the lock to safely insert the records. */
462 pthread_rwlock_rdlock (&db
->lock
);
464 if (cache_add (req
->type
, key_copy
, req
->key_len
, &dataset
->head
, true,
466 /* Ensure the data can be recovered. */
467 dataset
->head
.usable
= false;
469 pthread_rwlock_unlock (&db
->lock
);
471 /* Mark the old entry as obsolete. */
479 addhstai (struct database_dyn
*db
, int fd
, request_header
*req
, void *key
,
482 addhstaiX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
487 readdhstai (struct database_dyn
*db
, struct hashentry
*he
, struct datahead
*dh
)
495 addhstaiX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);