1 /* Cache handling for host lookup.
2 Copyright (C) 1998-2002, 2003, 2004, 2005 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library 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 GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
34 #include <arpa/inet.h>
35 #include <arpa/nameser.h>
37 #include <stackinfo.h>
42 # include <kernel-features.h>
46 /* This is the standard reply in case the service is disabled. */
47 static const hst_response_header disabled
=
49 .version
= NSCD_VERSION
,
56 .error
= NETDB_INTERNAL
59 /* This is the struct describing how to write this record. */
60 const struct iovec hst_iov_disabled
=
62 .iov_base
= (void *) &disabled
,
63 .iov_len
= sizeof (disabled
)
67 /* This is the standard reply in case we haven't found the dataset. */
68 static const hst_response_header notfound
=
70 .version
= NSCD_VERSION
,
77 .error
= HOST_NOT_FOUND
82 cache_addhst (struct database_dyn
*db
, int fd
, request_header
*req
,
83 const void *key
, struct hostent
*hst
, uid_t owner
,
84 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
+ db
->negtimeout
;
137 /* This is the reply. */
138 memcpy (&dataset
->resp
, ¬found
, total
);
140 /* Copy the key data. */
141 memcpy (dataset
->strdata
, key
, req
->key_len
);
143 /* If necessary, we also propagate the data to disk. */
147 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
148 msync ((void *) pval
,
149 ((uintptr_t) dataset
& pagesize_m1
)
150 + sizeof (struct dataset
) + req
->key_len
, MS_ASYNC
);
153 /* Now get the lock to safely insert the records. */
154 pthread_rwlock_rdlock (&db
->lock
);
156 if (cache_add (req
->type
, &dataset
->strdata
, req
->key_len
,
157 &dataset
->head
, true, db
, owner
) < 0)
158 /* Ensure the data can be recovered. */
159 dataset
->head
.usable
= false;
161 pthread_rwlock_unlock (&db
->lock
);
163 /* Mark the old entry as obsolete. */
168 ++db
->head
->addfailed
;
173 /* Determine the I/O structure. */
174 size_t h_name_len
= strlen (hst
->h_name
) + 1;
175 size_t h_aliases_cnt
;
176 uint32_t *h_aliases_len
;
177 size_t h_addr_list_cnt
;
181 char *key_copy
= NULL
;
185 /* Determine the number of aliases. */
187 for (cnt
= 0; hst
->h_aliases
[cnt
] != NULL
; ++cnt
)
189 /* Determine the length of all aliases. */
190 h_aliases_len
= (uint32_t *) alloca (h_aliases_cnt
* sizeof (uint32_t));
192 for (cnt
= 0; cnt
< h_aliases_cnt
; ++cnt
)
194 h_aliases_len
[cnt
] = strlen (hst
->h_aliases
[cnt
]) + 1;
195 total
+= h_aliases_len
[cnt
];
198 /* Determine the number of addresses. */
200 for (cnt
= 0; hst
->h_addr_list
[cnt
]; ++cnt
)
203 if (h_addr_list_cnt
== 0)
207 total
+= (sizeof (struct dataset
)
209 + h_aliases_cnt
* sizeof (uint32_t)
210 + h_addr_list_cnt
* hst
->h_length
);
213 /* If we refill the cache, first assume the reconrd did not
214 change. Allocate memory on the cache since it is likely
215 discarded anyway. If it turns out to be necessary to have a
216 new record we can still allocate real memory. */
217 bool alloca_used
= false;
220 /* If the record contains more than one IP address (used for
221 load balancing etc) don't cache the entry. This is something
222 the current cache handling cannot handle and it is more than
223 questionable whether it is worthwhile complicating the cache
224 handling just for handling such a special case. */
225 if (he
== NULL
&& hst
->h_addr_list
[1] == NULL
)
227 dataset
= (struct dataset
*) mempool_alloc (db
,
228 total
+ req
->key_len
);
230 ++db
->head
->addfailed
;
235 /* We cannot permanently add the result in the moment. But
236 we can provide the result as is. Store the data in some
238 dataset
= (struct dataset
*) alloca (total
+ req
->key_len
);
240 /* We cannot add this record to the permanent database. */
244 dataset
->head
.allocsize
= total
+ req
->key_len
;
245 dataset
->head
.recsize
= total
- offsetof (struct dataset
, resp
);
246 dataset
->head
.notfound
= false;
247 dataset
->head
.nreloads
= he
== NULL
? 0 : (dh
->nreloads
+ 1);
248 dataset
->head
.usable
= true;
250 /* Compute the timeout time. */
251 dataset
->head
.timeout
= t
+ db
->postimeout
;
253 dataset
->resp
.version
= NSCD_VERSION
;
254 dataset
->resp
.found
= 1;
255 dataset
->resp
.h_name_len
= h_name_len
;
256 dataset
->resp
.h_aliases_cnt
= h_aliases_cnt
;
257 dataset
->resp
.h_addrtype
= hst
->h_addrtype
;
258 dataset
->resp
.h_length
= hst
->h_length
;
259 dataset
->resp
.h_addr_list_cnt
= h_addr_list_cnt
;
260 dataset
->resp
.error
= NETDB_SUCCESS
;
262 cp
= dataset
->strdata
;
264 cp
= mempcpy (cp
, hst
->h_name
, h_name_len
);
265 cp
= mempcpy (cp
, h_aliases_len
, h_aliases_cnt
* sizeof (uint32_t));
267 /* The normal addresses first. */
269 for (cnt
= 0; cnt
< h_addr_list_cnt
; ++cnt
)
270 cp
= mempcpy (cp
, hst
->h_addr_list
[cnt
], hst
->h_length
);
272 /* Then the aliases. */
274 for (cnt
= 0; cnt
< h_aliases_cnt
; ++cnt
)
275 cp
= mempcpy (cp
, hst
->h_aliases
[cnt
], h_aliases_len
[cnt
]);
278 == dataset
->strdata
+ total
- offsetof (struct dataset
,
281 /* If we are adding a GETHOSTBYNAME{,v6} entry we must be prepared
282 that the answer we get from the NSS does not contain the key
283 itself. This is the case if the resolver is used and the name
284 is extended by the domainnames from /etc/resolv.conf. Therefore
285 we explicitly add the name here. */
286 key_copy
= memcpy (cp
, key
, req
->key_len
);
288 /* Now we can determine whether on refill we have to create a new
294 if (total
+ req
->key_len
== dh
->allocsize
295 && total
- offsetof (struct dataset
, resp
) == dh
->recsize
296 && memcmp (&dataset
->resp
, dh
->data
,
297 dh
->allocsize
- offsetof (struct dataset
, resp
)) == 0)
299 /* The data has not changed. We will just bump the
300 timeout value. Note that the new record has been
301 allocated on the stack and need not be freed. */
302 dh
->timeout
= dataset
->head
.timeout
;
307 /* We have to create a new record. Just allocate
308 appropriate memory and copy it. */
310 = (struct dataset
*) mempool_alloc (db
, total
+ req
->key_len
);
313 /* Adjust pointers into the memory block. */
314 addresses
= (char *) newp
+ (addresses
- (char *) dataset
);
315 aliases
= (char *) newp
+ (aliases
- (char *) dataset
);
316 if (key_copy
!= NULL
)
317 key_copy
= (char *) newp
+ (key_copy
- (char *) dataset
);
319 dataset
= memcpy (newp
, dataset
, total
+ req
->key_len
);
323 /* Mark the old record as obsolete. */
329 /* We write the dataset before inserting it to the database
330 since while inserting this thread might block and so would
331 unnecessarily keep the receiver waiting. */
335 if (__builtin_expect (db
->mmap_used
, 1))
337 assert (db
->wr_fd
!= -1);
338 assert ((char *) &dataset
->resp
> (char *) db
->data
);
339 assert ((char *) &dataset
->resp
- (char *) db
->head
341 <= (sizeof (struct database_pers_head
)
342 + db
->head
->module
* sizeof (ref_t
)
343 + db
->head
->data_size
));
344 written
= sendfileall (fd
, db
->wr_fd
,
345 (char *) &dataset
->resp
346 - (char *) db
->head
, total
);
347 # ifndef __ASSUME_SENDFILE
348 if (written
== -1 && errno
== ENOSYS
)
353 # ifndef __ASSUME_SENDFILE
357 written
= writeall (fd
, &dataset
->resp
, total
);
360 /* Add the record to the database. But only if it has not been
363 If the record contains more than one IP address (used for
364 load balancing etc) don't cache the entry. This is something
365 the current cache handling cannot handle and it is more than
366 questionable whether it is worthwhile complicating the cache
367 handling just for handling such a special case. */
370 /* If necessary, we also propagate the data to disk. */
374 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
375 msync ((void *) pval
,
376 ((uintptr_t) dataset
& pagesize_m1
)
377 + total
+ req
->key_len
, MS_ASYNC
);
380 addr_list_type
= (hst
->h_length
== NS_INADDRSZ
381 ? GETHOSTBYADDR
: GETHOSTBYADDRv6
);
383 /* Now get the lock to safely insert the records. */
384 pthread_rwlock_rdlock (&db
->lock
);
386 /* NB: the following code is really complicated. It has
387 seemlingly duplicated code paths which do the same. The
388 problem is that we always must add the hash table entry
389 with the FIRST flag set first. Otherwise we get dangling
390 pointers in case memory allocation fails. */
391 assert (hst
->h_addr_list
[1] == NULL
);
393 /* Avoid adding names if more than one address is available. See
394 above for more info. */
395 assert (req
->type
== GETHOSTBYNAME
396 || req
->type
== GETHOSTBYNAMEv6
397 || req
->type
== GETHOSTBYADDR
398 || req
->type
== GETHOSTBYADDRv6
);
400 if (cache_add (req
->type
, key_copy
, req
->key_len
,
401 &dataset
->head
, true, db
, owner
) < 0)
402 /* Could not allocate memory. Make sure the
403 data gets discarded. */
404 dataset
->head
.usable
= false;
406 pthread_rwlock_unlock (&db
->lock
);
410 if (__builtin_expect (written
!= total
, 0) && debug_level
> 0)
413 dbg_log (_("short write in %s: %s"), __FUNCTION__
,
414 strerror_r (errno
, buf
, sizeof (buf
)));
420 lookup (int type
, void *key
, struct hostent
*resultbufp
, char *buffer
,
421 size_t buflen
, struct hostent
**hst
)
423 if (type
== GETHOSTBYNAME
)
424 return __gethostbyname2_r (key
, AF_INET
, resultbufp
, buffer
, buflen
, hst
,
426 if (type
== GETHOSTBYNAMEv6
)
427 return __gethostbyname2_r (key
, AF_INET6
, resultbufp
, buffer
, buflen
, hst
,
429 if (type
== GETHOSTBYADDR
)
430 return __gethostbyaddr_r (key
, NS_INADDRSZ
, AF_INET
, resultbufp
, buffer
,
431 buflen
, hst
, &h_errno
);
432 return __gethostbyaddr_r (key
, NS_IN6ADDRSZ
, AF_INET6
, resultbufp
, buffer
,
433 buflen
, hst
, &h_errno
);
438 addhstbyX (struct database_dyn
*db
, int fd
, request_header
*req
,
439 void *key
, uid_t uid
, struct hashentry
*he
, struct datahead
*dh
)
441 /* Search for the entry matching the key. Please note that we don't
442 look again in the table whether the dataset is now available. We
443 simply insert it. It does not matter if it is in there twice. The
444 pruning function only will look at the timestamp. */
446 char *buffer
= (char *) alloca (buflen
);
447 struct hostent resultbuf
;
449 bool use_malloc
= false;
452 if (__builtin_expect (debug_level
> 0, 0))
455 char buf
[INET6_ADDRSTRLEN
+ 1];
456 if (req
->type
== GETHOSTBYNAME
|| req
->type
== GETHOSTBYNAMEv6
)
459 str
= inet_ntop (req
->type
== GETHOSTBYADDR
? AF_INET
: AF_INET6
,
460 key
, buf
, sizeof (buf
));
463 dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) str
);
465 dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) str
);
472 oldeuid
= geteuid ();
473 pthread_seteuid_np (uid
);
477 while (lookup (req
->type
, key
, &resultbuf
, buffer
, buflen
, &hst
) != 0
478 && h_errno
== NETDB_INTERNAL
479 && (errval
= errno
) == ERANGE
)
481 char *old_buffer
= buffer
;
484 if (__builtin_expect (buflen
> 32768, 0))
487 buffer
= (char *) realloc (use_malloc
? buffer
: NULL
, buflen
);
490 /* We ran out of memory. We cannot do anything but
491 sending a negative response. In reality this should
496 /* We set the error to indicate this is (possibly) a
497 temporary error and that it does not mean the entry
498 is not available at all. */
505 /* Allocate a new buffer on the stack. If possible combine it
506 with the previously allocated buffer. */
507 buffer
= (char *) extend_alloca (buffer
, buflen
, 2 * buflen
);
512 pthread_seteuid_np (oldeuid
);
515 cache_addhst (db
, fd
, req
, key
, hst
, uid
, he
, dh
,
516 h_errno
== TRY_AGAIN
? errval
: 0);
524 addhstbyname (struct database_dyn
*db
, int fd
, request_header
*req
,
525 void *key
, uid_t uid
)
527 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
532 readdhstbyname (struct database_dyn
*db
, struct hashentry
*he
,
537 .type
= GETHOSTBYNAME
,
541 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
546 addhstbyaddr (struct database_dyn
*db
, int fd
, request_header
*req
,
547 void *key
, uid_t uid
)
549 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
554 readdhstbyaddr (struct database_dyn
*db
, struct hashentry
*he
,
559 .type
= GETHOSTBYADDR
,
563 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
568 addhstbynamev6 (struct database_dyn
*db
, int fd
, request_header
*req
,
569 void *key
, uid_t uid
)
571 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
576 readdhstbynamev6 (struct database_dyn
*db
, struct hashentry
*he
,
581 .type
= GETHOSTBYNAMEv6
,
585 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
590 addhstbyaddrv6 (struct database_dyn
*db
, int fd
, request_header
*req
,
591 void *key
, uid_t uid
)
593 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
598 readdhstbyaddrv6 (struct database_dyn
*db
, struct hashentry
*he
,
603 .type
= GETHOSTBYADDRv6
,
607 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);