1 /* Cache handling for host lookup.
2 Copyright (C) 1998-2005, 2006, 2007 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
);
125 /* If we cannot permanently store the result, so be it. */
128 dataset
->head
.allocsize
= sizeof (struct dataset
) + req
->key_len
;
129 dataset
->head
.recsize
= total
;
130 dataset
->head
.notfound
= true;
131 dataset
->head
.nreloads
= 0;
132 dataset
->head
.usable
= true;
134 /* Compute the timeout time. */
135 dataset
->head
.timeout
= t
+ (ttl
== INT32_MAX
136 ? db
->negtimeout
: ttl
);
138 /* This is the reply. */
139 memcpy (&dataset
->resp
, ¬found
, total
);
141 /* Copy the key data. */
142 memcpy (dataset
->strdata
, key
, req
->key_len
);
144 /* If necessary, we also propagate the data to disk. */
148 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
149 msync ((void *) pval
,
150 ((uintptr_t) dataset
& pagesize_m1
)
151 + sizeof (struct dataset
) + req
->key_len
, MS_ASYNC
);
154 /* Now get the lock to safely insert the records. */
155 pthread_rwlock_rdlock (&db
->lock
);
157 if (cache_add (req
->type
, &dataset
->strdata
, req
->key_len
,
158 &dataset
->head
, true, db
, owner
) < 0)
159 /* Ensure the data can be recovered. */
160 dataset
->head
.usable
= false;
162 pthread_rwlock_unlock (&db
->lock
);
164 /* Mark the old entry as obsolete. */
169 ++db
->head
->addfailed
;
174 /* Determine the I/O structure. */
175 size_t h_name_len
= strlen (hst
->h_name
) + 1;
176 size_t h_aliases_cnt
;
177 uint32_t *h_aliases_len
;
178 size_t h_addr_list_cnt
;
182 char *key_copy
= NULL
;
186 /* Determine the number of aliases. */
188 for (cnt
= 0; hst
->h_aliases
[cnt
] != NULL
; ++cnt
)
190 /* Determine the length of all aliases. */
191 h_aliases_len
= (uint32_t *) alloca (h_aliases_cnt
* sizeof (uint32_t));
193 for (cnt
= 0; cnt
< h_aliases_cnt
; ++cnt
)
195 h_aliases_len
[cnt
] = strlen (hst
->h_aliases
[cnt
]) + 1;
196 total
+= h_aliases_len
[cnt
];
199 /* Determine the number of addresses. */
201 while (hst
->h_addr_list
[h_addr_list_cnt
] != NULL
)
204 if (h_addr_list_cnt
== 0)
208 total
+= (sizeof (struct dataset
)
210 + h_aliases_cnt
* sizeof (uint32_t)
211 + h_addr_list_cnt
* hst
->h_length
);
214 /* If we refill the cache, first assume the reconrd did not
215 change. Allocate memory on the cache since it is likely
216 discarded anyway. If it turns out to be necessary to have a
217 new record we can still allocate real memory. */
218 bool alloca_used
= false;
221 /* If the record contains more than one IP address (used for
222 load balancing etc) don't cache the entry. This is something
223 the current cache handling cannot handle and it is more than
224 questionable whether it is worthwhile complicating the cache
225 handling just for handling such a special case. */
226 if (he
== NULL
&& h_addr_list_cnt
== 1)
228 dataset
= (struct dataset
*) mempool_alloc (db
,
229 total
+ req
->key_len
);
231 ++db
->head
->addfailed
;
236 /* We cannot permanently add the result in the moment. But
237 we can provide the result as is. Store the data in some
239 dataset
= (struct dataset
*) alloca (total
+ req
->key_len
);
241 /* We cannot add this record to the permanent database. */
245 dataset
->head
.allocsize
= total
+ req
->key_len
;
246 dataset
->head
.recsize
= total
- offsetof (struct dataset
, resp
);
247 dataset
->head
.notfound
= false;
248 dataset
->head
.nreloads
= he
== NULL
? 0 : (dh
->nreloads
+ 1);
249 dataset
->head
.usable
= true;
251 /* Compute the timeout time. */
252 dataset
->head
.timeout
= t
+ (ttl
== INT32_MAX
? db
->postimeout
: ttl
);
254 dataset
->resp
.version
= NSCD_VERSION
;
255 dataset
->resp
.found
= 1;
256 dataset
->resp
.h_name_len
= h_name_len
;
257 dataset
->resp
.h_aliases_cnt
= h_aliases_cnt
;
258 dataset
->resp
.h_addrtype
= hst
->h_addrtype
;
259 dataset
->resp
.h_length
= hst
->h_length
;
260 dataset
->resp
.h_addr_list_cnt
= h_addr_list_cnt
;
261 dataset
->resp
.error
= NETDB_SUCCESS
;
263 cp
= dataset
->strdata
;
265 cp
= mempcpy (cp
, hst
->h_name
, h_name_len
);
266 cp
= mempcpy (cp
, h_aliases_len
, h_aliases_cnt
* sizeof (uint32_t));
268 /* The normal addresses first. */
270 for (cnt
= 0; cnt
< h_addr_list_cnt
; ++cnt
)
271 cp
= mempcpy (cp
, hst
->h_addr_list
[cnt
], hst
->h_length
);
273 /* Then the aliases. */
275 for (cnt
= 0; cnt
< h_aliases_cnt
; ++cnt
)
276 cp
= mempcpy (cp
, hst
->h_aliases
[cnt
], h_aliases_len
[cnt
]);
279 == dataset
->strdata
+ total
- offsetof (struct dataset
,
282 /* If we are adding a GETHOSTBYNAME{,v6} entry we must be prepared
283 that the answer we get from the NSS does not contain the key
284 itself. This is the case if the resolver is used and the name
285 is extended by the domainnames from /etc/resolv.conf. Therefore
286 we explicitly add the name here. */
287 key_copy
= memcpy (cp
, key
, req
->key_len
);
289 /* Now we can determine whether on refill we have to create a new
295 if (total
+ req
->key_len
== dh
->allocsize
296 && total
- offsetof (struct dataset
, resp
) == dh
->recsize
297 && memcmp (&dataset
->resp
, dh
->data
,
298 dh
->allocsize
- offsetof (struct dataset
, resp
)) == 0)
300 /* The data has not changed. We will just bump the
301 timeout value. Note that the new record has been
302 allocated on the stack and need not be freed. */
303 assert (h_addr_list_cnt
== 1);
304 dh
->timeout
= dataset
->head
.timeout
;
309 if (h_addr_list_cnt
== 1)
311 /* We have to create a new record. Just allocate
312 appropriate memory and copy it. */
314 = (struct dataset
*) mempool_alloc (db
,
315 total
+ req
->key_len
);
318 /* Adjust pointers into the memory block. */
319 addresses
= (char *) newp
+ (addresses
321 aliases
= (char *) newp
+ (aliases
- (char *) dataset
);
322 assert (key_copy
!= NULL
);
323 key_copy
= (char *) newp
+ (key_copy
- (char *) dataset
);
325 dataset
= memcpy (newp
, dataset
, total
+ req
->key_len
);
329 ++db
->head
->addfailed
;
332 /* Mark the old record as obsolete. */
338 /* We write the dataset before inserting it to the database
339 since while inserting this thread might block and so would
340 unnecessarily keep the receiver waiting. */
344 if (__builtin_expect (db
->mmap_used
, 1) && !alloca_used
)
346 assert (db
->wr_fd
!= -1);
347 assert ((char *) &dataset
->resp
> (char *) db
->data
);
348 assert ((char *) &dataset
->resp
- (char *) db
->head
350 <= (sizeof (struct database_pers_head
)
351 + db
->head
->module
* sizeof (ref_t
)
352 + db
->head
->data_size
));
353 written
= sendfileall (fd
, db
->wr_fd
,
354 (char *) &dataset
->resp
355 - (char *) db
->head
, total
);
356 # ifndef __ASSUME_SENDFILE
357 if (written
== -1 && errno
== ENOSYS
)
362 # ifndef __ASSUME_SENDFILE
366 written
= writeall (fd
, &dataset
->resp
, total
);
369 /* Add the record to the database. But only if it has not been
372 If the record contains more than one IP address (used for
373 load balancing etc) don't cache the entry. This is something
374 the current cache handling cannot handle and it is more than
375 questionable whether it is worthwhile complicating the cache
376 handling just for handling such a special case. */
379 /* If necessary, we also propagate the data to disk. */
383 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
384 msync ((void *) pval
,
385 ((uintptr_t) dataset
& pagesize_m1
)
386 + total
+ req
->key_len
, MS_ASYNC
);
389 addr_list_type
= (hst
->h_length
== NS_INADDRSZ
390 ? GETHOSTBYADDR
: GETHOSTBYADDRv6
);
392 /* Now get the lock to safely insert the records. */
393 pthread_rwlock_rdlock (&db
->lock
);
395 /* NB: the following code is really complicated. It has
396 seemlingly duplicated code paths which do the same. The
397 problem is that we always must add the hash table entry
398 with the FIRST flag set first. Otherwise we get dangling
399 pointers in case memory allocation fails. */
400 assert (hst
->h_addr_list
[1] == NULL
);
402 /* Avoid adding names if more than one address is available. See
403 above for more info. */
404 assert (req
->type
== GETHOSTBYNAME
405 || req
->type
== GETHOSTBYNAMEv6
406 || req
->type
== GETHOSTBYADDR
407 || req
->type
== GETHOSTBYADDRv6
);
409 if (cache_add (req
->type
, key_copy
, req
->key_len
,
410 &dataset
->head
, true, db
, owner
) < 0)
411 /* Could not allocate memory. Make sure the
412 data gets discarded. */
413 dataset
->head
.usable
= false;
415 pthread_rwlock_unlock (&db
->lock
);
419 if (__builtin_expect (written
!= total
, 0) && debug_level
> 0)
422 dbg_log (_("short write in %s: %s"), __FUNCTION__
,
423 strerror_r (errno
, buf
, sizeof (buf
)));
429 lookup (int type
, void *key
, struct hostent
*resultbufp
, char *buffer
,
430 size_t buflen
, struct hostent
**hst
, int32_t *ttlp
)
432 if (type
== GETHOSTBYNAME
)
433 return __gethostbyname3_r (key
, AF_INET
, resultbufp
, buffer
, buflen
, hst
,
434 &h_errno
, ttlp
, NULL
);
435 if (type
== GETHOSTBYNAMEv6
)
436 return __gethostbyname3_r (key
, AF_INET6
, resultbufp
, buffer
, buflen
, hst
,
437 &h_errno
, ttlp
, NULL
);
438 if (type
== GETHOSTBYADDR
)
439 return __gethostbyaddr2_r (key
, NS_INADDRSZ
, AF_INET
, resultbufp
, buffer
,
440 buflen
, hst
, &h_errno
, ttlp
);
441 return __gethostbyaddr2_r (key
, NS_IN6ADDRSZ
, AF_INET6
, resultbufp
, buffer
,
442 buflen
, hst
, &h_errno
, ttlp
);
447 addhstbyX (struct database_dyn
*db
, int fd
, request_header
*req
,
448 void *key
, uid_t uid
, struct hashentry
*he
, struct datahead
*dh
)
450 /* Search for the entry matching the key. Please note that we don't
451 look again in the table whether the dataset is now available. We
452 simply insert it. It does not matter if it is in there twice. The
453 pruning function only will look at the timestamp. */
455 char *buffer
= (char *) alloca (buflen
);
456 struct hostent resultbuf
;
458 bool use_malloc
= false;
460 int32_t ttl
= INT32_MAX
;
462 if (__builtin_expect (debug_level
> 0, 0))
465 char buf
[INET6_ADDRSTRLEN
+ 1];
466 if (req
->type
== GETHOSTBYNAME
|| req
->type
== GETHOSTBYNAMEv6
)
469 str
= inet_ntop (req
->type
== GETHOSTBYADDR
? AF_INET
: AF_INET6
,
470 key
, buf
, sizeof (buf
));
473 dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) str
);
475 dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) str
);
478 while (lookup (req
->type
, key
, &resultbuf
, buffer
, buflen
, &hst
, &ttl
) != 0
479 && h_errno
== NETDB_INTERNAL
480 && (errval
= errno
) == ERANGE
)
484 if (__builtin_expect (buflen
> 32768, 0))
486 char *old_buffer
= buffer
;
488 buffer
= (char *) realloc (use_malloc
? buffer
: NULL
, buflen
);
491 /* We ran out of memory. We cannot do anything but
492 sending a negative response. In reality this should
497 /* We set the error to indicate this is (possibly) a
498 temporary error and that it does not mean the entry
499 is not available at all. */
506 /* Allocate a new buffer on the stack. If possible combine it
507 with the previously allocated buffer. */
508 buffer
= (char *) extend_alloca (buffer
, buflen
, 2 * buflen
);
511 cache_addhst (db
, fd
, req
, key
, hst
, uid
, he
, dh
,
512 h_errno
== TRY_AGAIN
? errval
: 0, ttl
);
520 addhstbyname (struct database_dyn
*db
, int fd
, request_header
*req
,
521 void *key
, uid_t uid
)
523 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
528 readdhstbyname (struct database_dyn
*db
, struct hashentry
*he
,
533 .type
= GETHOSTBYNAME
,
537 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
542 addhstbyaddr (struct database_dyn
*db
, int fd
, request_header
*req
,
543 void *key
, uid_t uid
)
545 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
550 readdhstbyaddr (struct database_dyn
*db
, struct hashentry
*he
,
555 .type
= GETHOSTBYADDR
,
559 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
564 addhstbynamev6 (struct database_dyn
*db
, int fd
, request_header
*req
,
565 void *key
, uid_t uid
)
567 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
572 readdhstbynamev6 (struct database_dyn
*db
, struct hashentry
*he
,
577 .type
= GETHOSTBYNAMEv6
,
581 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
586 addhstbyaddrv6 (struct database_dyn
*db
, int fd
, request_header
*req
,
587 void *key
, uid_t uid
)
589 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
594 readdhstbyaddrv6 (struct database_dyn
*db
, struct hashentry
*he
,
599 .type
= GETHOSTBYADDRv6
,
603 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);