1 /* Cache handling for host lookup.
2 Copyright (C) 1998-2005, 2006, 2007, 2008 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
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. */
33 #include <arpa/inet.h>
34 #include <arpa/nameser.h>
36 #include <stackinfo.h>
41 # include <kernel-features.h>
45 /* This is the standard reply in case the service is disabled. */
46 static const hst_response_header disabled
=
48 .version
= NSCD_VERSION
,
55 .error
= NETDB_INTERNAL
58 /* This is the struct describing how to write this record. */
59 const struct iovec hst_iov_disabled
=
61 .iov_base
= (void *) &disabled
,
62 .iov_len
= sizeof (disabled
)
66 /* This is the standard reply in case we haven't found the dataset. */
67 static const hst_response_header notfound
=
69 .version
= NSCD_VERSION
,
76 .error
= HOST_NOT_FOUND
81 cache_addhst (struct database_dyn
*db
, int fd
, request_header
*req
,
82 const void *key
, struct hostent
*hst
, uid_t owner
,
83 struct hashentry
*he
, struct datahead
*dh
, int errval
,
88 time_t t
= time (NULL
);
90 /* We allocate all data in one memory block: the iov vector,
91 the response header and the dataset itself. */
95 hst_response_header resp
;
99 assert (offsetof (struct dataset
, resp
) == offsetof (struct datahead
, data
));
103 if (he
!= NULL
&& errval
== EAGAIN
)
105 /* If we have an old record available but cannot find one
106 now because the service is not available we keep the old
107 record and make sure it does not get removed. */
108 if (reload_count
!= UINT_MAX
)
109 /* Do not reset the value if we never not reload the record. */
110 dh
->nreloads
= reload_count
- 1;
116 /* We have no data. This means we send the standard reply for this
118 written
= total
= sizeof (notfound
);
121 written
= TEMP_FAILURE_RETRY (send (fd
, ¬found
, total
,
124 dataset
= mempool_alloc (db
, sizeof (struct dataset
) + req
->key_len
,
126 /* If we cannot permanently store the result, so be it. */
129 dataset
->head
.allocsize
= sizeof (struct dataset
) + req
->key_len
;
130 dataset
->head
.recsize
= total
;
131 dataset
->head
.notfound
= true;
132 dataset
->head
.nreloads
= 0;
133 dataset
->head
.usable
= true;
135 /* Compute the timeout time. */
136 dataset
->head
.timeout
= t
+ (ttl
== INT32_MAX
137 ? db
->negtimeout
: ttl
);
139 /* This is the reply. */
140 memcpy (&dataset
->resp
, ¬found
, total
);
142 /* Copy the key data. */
143 memcpy (dataset
->strdata
, key
, req
->key_len
);
145 /* If necessary, we also propagate the data to disk. */
149 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
150 msync ((void *) pval
,
151 ((uintptr_t) dataset
& pagesize_m1
)
152 + sizeof (struct dataset
) + req
->key_len
, MS_ASYNC
);
155 /* Now get the lock to safely insert the records. */
156 pthread_rwlock_rdlock (&db
->lock
);
158 if (cache_add (req
->type
, &dataset
->strdata
, req
->key_len
,
159 &dataset
->head
, true, db
, owner
) < 0)
160 /* Ensure the data can be recovered. */
161 dataset
->head
.usable
= false;
163 pthread_rwlock_unlock (&db
->lock
);
165 /* Mark the old entry as obsolete. */
170 ++db
->head
->addfailed
;
175 /* Determine the I/O structure. */
176 size_t h_name_len
= strlen (hst
->h_name
) + 1;
177 size_t h_aliases_cnt
;
178 uint32_t *h_aliases_len
;
179 size_t h_addr_list_cnt
;
183 char *key_copy
= NULL
;
187 /* Determine the number of aliases. */
189 for (cnt
= 0; hst
->h_aliases
[cnt
] != NULL
; ++cnt
)
191 /* Determine the length of all aliases. */
192 h_aliases_len
= (uint32_t *) alloca (h_aliases_cnt
* sizeof (uint32_t));
194 for (cnt
= 0; cnt
< h_aliases_cnt
; ++cnt
)
196 h_aliases_len
[cnt
] = strlen (hst
->h_aliases
[cnt
]) + 1;
197 total
+= h_aliases_len
[cnt
];
200 /* Determine the number of addresses. */
202 while (hst
->h_addr_list
[h_addr_list_cnt
] != NULL
)
205 if (h_addr_list_cnt
== 0)
209 total
+= (sizeof (struct dataset
)
211 + h_aliases_cnt
* sizeof (uint32_t)
212 + h_addr_list_cnt
* hst
->h_length
);
215 /* If we refill the cache, first assume the reconrd did not
216 change. Allocate memory on the cache since it is likely
217 discarded anyway. If it turns out to be necessary to have a
218 new record we can still allocate real memory. */
219 bool alloca_used
= false;
222 /* If the record contains more than one IP address (used for
223 load balancing etc) don't cache the entry. This is something
224 the current cache handling cannot handle and it is more than
225 questionable whether it is worthwhile complicating the cache
226 handling just for handling such a special case. */
227 if (he
== NULL
&& h_addr_list_cnt
== 1)
229 dataset
= (struct dataset
*) mempool_alloc (db
,
230 total
+ req
->key_len
,
233 ++db
->head
->addfailed
;
238 /* We cannot permanently add the result in the moment. But
239 we can provide the result as is. Store the data in some
241 dataset
= (struct dataset
*) alloca (total
+ req
->key_len
);
243 /* We cannot add this record to the permanent database. */
247 dataset
->head
.allocsize
= total
+ req
->key_len
;
248 dataset
->head
.recsize
= total
- offsetof (struct dataset
, resp
);
249 dataset
->head
.notfound
= false;
250 dataset
->head
.nreloads
= he
== NULL
? 0 : (dh
->nreloads
+ 1);
251 dataset
->head
.usable
= true;
253 /* Compute the timeout time. */
254 dataset
->head
.timeout
= t
+ (ttl
== INT32_MAX
? db
->postimeout
: ttl
);
256 dataset
->resp
.version
= NSCD_VERSION
;
257 dataset
->resp
.found
= 1;
258 dataset
->resp
.h_name_len
= h_name_len
;
259 dataset
->resp
.h_aliases_cnt
= h_aliases_cnt
;
260 dataset
->resp
.h_addrtype
= hst
->h_addrtype
;
261 dataset
->resp
.h_length
= hst
->h_length
;
262 dataset
->resp
.h_addr_list_cnt
= h_addr_list_cnt
;
263 dataset
->resp
.error
= NETDB_SUCCESS
;
265 cp
= dataset
->strdata
;
267 cp
= mempcpy (cp
, hst
->h_name
, h_name_len
);
268 cp
= mempcpy (cp
, h_aliases_len
, h_aliases_cnt
* sizeof (uint32_t));
270 /* The normal addresses first. */
272 for (cnt
= 0; cnt
< h_addr_list_cnt
; ++cnt
)
273 cp
= mempcpy (cp
, hst
->h_addr_list
[cnt
], hst
->h_length
);
275 /* Then the aliases. */
277 for (cnt
= 0; cnt
< h_aliases_cnt
; ++cnt
)
278 cp
= mempcpy (cp
, hst
->h_aliases
[cnt
], h_aliases_len
[cnt
]);
281 == dataset
->strdata
+ total
- offsetof (struct dataset
,
284 /* If we are adding a GETHOSTBYNAME{,v6} entry we must be prepared
285 that the answer we get from the NSS does not contain the key
286 itself. This is the case if the resolver is used and the name
287 is extended by the domainnames from /etc/resolv.conf. Therefore
288 we explicitly add the name here. */
289 key_copy
= memcpy (cp
, key
, req
->key_len
);
291 /* Now we can determine whether on refill we have to create a new
297 if (total
+ req
->key_len
== dh
->allocsize
298 && total
- offsetof (struct dataset
, resp
) == dh
->recsize
299 && memcmp (&dataset
->resp
, dh
->data
,
300 dh
->allocsize
- offsetof (struct dataset
, resp
)) == 0)
302 /* The data has not changed. We will just bump the
303 timeout value. Note that the new record has been
304 allocated on the stack and need not be freed. */
305 assert (h_addr_list_cnt
== 1);
306 dh
->timeout
= dataset
->head
.timeout
;
311 if (h_addr_list_cnt
== 1)
313 /* We have to create a new record. Just allocate
314 appropriate memory and copy it. */
316 = (struct dataset
*) mempool_alloc (db
,
317 total
+ req
->key_len
,
321 /* Adjust pointers into the memory block. */
322 addresses
= (char *) newp
+ (addresses
324 aliases
= (char *) newp
+ (aliases
- (char *) dataset
);
325 assert (key_copy
!= NULL
);
326 key_copy
= (char *) newp
+ (key_copy
- (char *) dataset
);
328 dataset
= memcpy (newp
, dataset
, total
+ req
->key_len
);
332 ++db
->head
->addfailed
;
335 /* Mark the old record as obsolete. */
341 /* We write the dataset before inserting it to the database
342 since while inserting this thread might block and so would
343 unnecessarily keep the receiver waiting. */
347 if (__builtin_expect (db
->mmap_used
, 1) && !alloca_used
)
349 assert (db
->wr_fd
!= -1);
350 assert ((char *) &dataset
->resp
> (char *) db
->data
);
351 assert ((char *) &dataset
->resp
- (char *) db
->head
353 <= (sizeof (struct database_pers_head
)
354 + db
->head
->module
* sizeof (ref_t
)
355 + db
->head
->data_size
));
356 written
= sendfileall (fd
, db
->wr_fd
,
357 (char *) &dataset
->resp
358 - (char *) db
->head
, total
);
359 # ifndef __ASSUME_SENDFILE
360 if (written
== -1 && errno
== ENOSYS
)
365 # ifndef __ASSUME_SENDFILE
369 written
= writeall (fd
, &dataset
->resp
, total
);
372 /* Add the record to the database. But only if it has not been
375 If the record contains more than one IP address (used for
376 load balancing etc) don't cache the entry. This is something
377 the current cache handling cannot handle and it is more than
378 questionable whether it is worthwhile complicating the cache
379 handling just for handling such a special case. */
382 /* If necessary, we also propagate the data to disk. */
386 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
387 msync ((void *) pval
,
388 ((uintptr_t) dataset
& pagesize_m1
)
389 + total
+ req
->key_len
, MS_ASYNC
);
392 addr_list_type
= (hst
->h_length
== NS_INADDRSZ
393 ? GETHOSTBYADDR
: GETHOSTBYADDRv6
);
395 /* Now get the lock to safely insert the records. */
396 pthread_rwlock_rdlock (&db
->lock
);
398 /* NB: the following code is really complicated. It has
399 seemlingly duplicated code paths which do the same. The
400 problem is that we always must add the hash table entry
401 with the FIRST flag set first. Otherwise we get dangling
402 pointers in case memory allocation fails. */
403 assert (hst
->h_addr_list
[1] == NULL
);
405 /* Avoid adding names if more than one address is available. See
406 above for more info. */
407 assert (req
->type
== GETHOSTBYNAME
408 || req
->type
== GETHOSTBYNAMEv6
409 || req
->type
== GETHOSTBYADDR
410 || req
->type
== GETHOSTBYADDRv6
);
412 if (cache_add (req
->type
, key_copy
, req
->key_len
,
413 &dataset
->head
, true, db
, owner
) < 0)
414 /* Could not allocate memory. Make sure the
415 data gets discarded. */
416 dataset
->head
.usable
= false;
418 pthread_rwlock_unlock (&db
->lock
);
422 if (__builtin_expect (written
!= total
, 0) && debug_level
> 0)
425 dbg_log (_("short write in %s: %s"), __FUNCTION__
,
426 strerror_r (errno
, buf
, sizeof (buf
)));
432 lookup (int type
, void *key
, struct hostent
*resultbufp
, char *buffer
,
433 size_t buflen
, struct hostent
**hst
, int32_t *ttlp
)
435 if (type
== GETHOSTBYNAME
)
436 return __gethostbyname3_r (key
, AF_INET
, resultbufp
, buffer
, buflen
, hst
,
437 &h_errno
, ttlp
, NULL
);
438 if (type
== GETHOSTBYNAMEv6
)
439 return __gethostbyname3_r (key
, AF_INET6
, resultbufp
, buffer
, buflen
, hst
,
440 &h_errno
, ttlp
, NULL
);
441 if (type
== GETHOSTBYADDR
)
442 return __gethostbyaddr2_r (key
, NS_INADDRSZ
, AF_INET
, resultbufp
, buffer
,
443 buflen
, hst
, &h_errno
, ttlp
);
444 return __gethostbyaddr2_r (key
, NS_IN6ADDRSZ
, AF_INET6
, resultbufp
, buffer
,
445 buflen
, hst
, &h_errno
, ttlp
);
450 addhstbyX (struct database_dyn
*db
, int fd
, request_header
*req
,
451 void *key
, uid_t uid
, struct hashentry
*he
, struct datahead
*dh
)
453 /* Search for the entry matching the key. Please note that we don't
454 look again in the table whether the dataset is now available. We
455 simply insert it. It does not matter if it is in there twice. The
456 pruning function only will look at the timestamp. */
458 char *buffer
= (char *) alloca (buflen
);
459 struct hostent resultbuf
;
461 bool use_malloc
= false;
463 int32_t ttl
= INT32_MAX
;
465 if (__builtin_expect (debug_level
> 0, 0))
468 char buf
[INET6_ADDRSTRLEN
+ 1];
469 if (req
->type
== GETHOSTBYNAME
|| req
->type
== GETHOSTBYNAMEv6
)
472 str
= inet_ntop (req
->type
== GETHOSTBYADDR
? AF_INET
: AF_INET6
,
473 key
, buf
, sizeof (buf
));
476 dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) str
);
478 dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) str
);
481 while (lookup (req
->type
, key
, &resultbuf
, buffer
, buflen
, &hst
, &ttl
) != 0
482 && h_errno
== NETDB_INTERNAL
483 && (errval
= errno
) == ERANGE
)
487 if (__builtin_expect (buflen
> 32768, 0))
489 char *old_buffer
= buffer
;
491 buffer
= (char *) realloc (use_malloc
? buffer
: NULL
, buflen
);
494 /* We ran out of memory. We cannot do anything but
495 sending a negative response. In reality this should
500 /* We set the error to indicate this is (possibly) a
501 temporary error and that it does not mean the entry
502 is not available at all. */
509 /* Allocate a new buffer on the stack. If possible combine it
510 with the previously allocated buffer. */
511 buffer
= (char *) extend_alloca (buffer
, buflen
, 2 * buflen
);
514 cache_addhst (db
, fd
, req
, key
, hst
, uid
, he
, dh
,
515 h_errno
== TRY_AGAIN
? errval
: 0, ttl
);
523 addhstbyname (struct database_dyn
*db
, int fd
, request_header
*req
,
524 void *key
, uid_t uid
)
526 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
531 readdhstbyname (struct database_dyn
*db
, struct hashentry
*he
,
536 .type
= GETHOSTBYNAME
,
540 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
545 addhstbyaddr (struct database_dyn
*db
, int fd
, request_header
*req
,
546 void *key
, uid_t uid
)
548 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
553 readdhstbyaddr (struct database_dyn
*db
, struct hashentry
*he
,
558 .type
= GETHOSTBYADDR
,
562 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
567 addhstbynamev6 (struct database_dyn
*db
, int fd
, request_header
*req
,
568 void *key
, uid_t uid
)
570 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
575 readdhstbynamev6 (struct database_dyn
*db
, struct hashentry
*he
,
580 .type
= GETHOSTBYNAMEv6
,
584 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
589 addhstbyaddrv6 (struct database_dyn
*db
, int fd
, request_header
*req
,
590 void *key
, uid_t uid
)
592 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
597 readdhstbyaddrv6 (struct database_dyn
*db
, struct hashentry
*he
,
602 .type
= GETHOSTBYADDRv6
,
606 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);