1 /* Cache handling for host lookup.
2 Copyright (C) 1998-2002, 2003, 2004 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>
43 /* This is the standard reply in case the service is disabled. */
44 static const hst_response_header disabled
=
46 .version
= NSCD_VERSION
,
53 .error
= NETDB_INTERNAL
56 /* This is the struct describing how to write this record. */
57 const struct iovec hst_iov_disabled
=
59 .iov_base
= (void *) &disabled
,
60 .iov_len
= sizeof (disabled
)
64 /* This is the standard reply in case we haven't found the dataset. */
65 static const hst_response_header notfound
=
67 .version
= NSCD_VERSION
,
74 .error
= HOST_NOT_FOUND
79 cache_addhst (struct database_dyn
*db
, int fd
, request_header
*req
,
80 const void *key
, struct hostent
*hst
, uid_t owner
,
81 struct hashentry
*he
, struct datahead
*dh
, int errval
)
85 time_t t
= time (NULL
);
87 /* We allocate all data in one memory block: the iov vector,
88 the response header and the dataset itself. */
92 hst_response_header resp
;
96 assert (offsetof (struct dataset
, resp
) == offsetof (struct datahead
, data
));
100 if (he
!= NULL
&& errval
== EAGAIN
)
102 /* If we have an old record available but cannot find one
103 now because the service is not available we keep the old
104 record and make sure it does not get removed. */
105 if (reload_count
!= UINT_MAX
)
106 /* Do not reset the value if we never not reload the record. */
107 dh
->nreloads
= reload_count
- 1;
113 /* We have no data. This means we send the standard reply for this
115 written
= total
= sizeof (notfound
);
118 written
= TEMP_FAILURE_RETRY (write (fd
, ¬found
, total
));
120 dataset
= mempool_alloc (db
, sizeof (struct dataset
) + req
->key_len
);
121 /* If we cannot permanently store the result, so be it. */
124 dataset
->head
.allocsize
= sizeof (struct dataset
) + req
->key_len
;
125 dataset
->head
.recsize
= total
;
126 dataset
->head
.notfound
= true;
127 dataset
->head
.nreloads
= 0;
128 dataset
->head
.usable
= true;
130 /* Compute the timeout time. */
131 dataset
->head
.timeout
= t
+ db
->negtimeout
;
133 /* This is the reply. */
134 memcpy (&dataset
->resp
, ¬found
, total
);
136 /* Copy the key data. */
137 memcpy (dataset
->strdata
, key
, req
->key_len
);
139 /* If necessary, we also propagate the data to disk. */
143 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
144 msync ((void *) pval
,
145 ((uintptr_t) dataset
& pagesize_m1
)
146 + sizeof (struct dataset
) + req
->key_len
, MS_ASYNC
);
149 /* Now get the lock to safely insert the records. */
150 pthread_rwlock_rdlock (&db
->lock
);
152 if (cache_add (req
->type
, &dataset
->strdata
, req
->key_len
,
153 &dataset
->head
, true, db
, owner
) < 0)
154 /* Ensure the data can be recovered. */
155 dataset
->head
.usable
= false;
157 pthread_rwlock_unlock (&db
->lock
);
159 /* Mark the old entry as obsolete. */
164 ++db
->head
->addfailed
;
169 /* Determine the I/O structure. */
170 size_t h_name_len
= strlen (hst
->h_name
) + 1;
171 size_t h_aliases_cnt
;
172 uint32_t *h_aliases_len
;
173 size_t h_addr_list_cnt
;
177 char *key_copy
= NULL
;
181 /* Determine the number of aliases. */
183 for (cnt
= 0; hst
->h_aliases
[cnt
] != NULL
; ++cnt
)
185 /* Determine the length of all aliases. */
186 h_aliases_len
= (uint32_t *) alloca (h_aliases_cnt
* sizeof (uint32_t));
188 for (cnt
= 0; cnt
< h_aliases_cnt
; ++cnt
)
190 h_aliases_len
[cnt
] = strlen (hst
->h_aliases
[cnt
]) + 1;
191 total
+= h_aliases_len
[cnt
];
194 /* Determine the number of addresses. */
196 for (cnt
= 0; hst
->h_addr_list
[cnt
]; ++cnt
)
199 if (h_addr_list_cnt
== 0)
203 total
+= (sizeof (struct dataset
)
205 + h_aliases_cnt
* sizeof (uint32_t)
206 + h_addr_list_cnt
* hst
->h_length
);
209 /* If we refill the cache, first assume the reconrd did not
210 change. Allocate memory on the cache since it is likely
211 discarded anyway. If it turns out to be necessary to have a
212 new record we can still allocate real memory. */
213 bool alloca_used
= false;
216 /* If the record contains more than one IP address (used for
217 load balancing etc) don't cache the entry. This is something
218 the current cache handling cannot handle and it is more than
219 questionable whether it is worthwhile complicating the cache
220 handling just for handling such a special case. */
221 if (he
== NULL
&& hst
->h_addr_list
[1] == NULL
)
223 dataset
= (struct dataset
*) mempool_alloc (db
,
224 total
+ req
->key_len
);
226 ++db
->head
->addfailed
;
231 /* We cannot permanently add the result in the moment. But
232 we can provide the result as is. Store the data in some
234 dataset
= (struct dataset
*) alloca (total
+ req
->key_len
);
236 /* We cannot add this record to the permanent database. */
240 dataset
->head
.allocsize
= total
+ req
->key_len
;
241 dataset
->head
.recsize
= total
- offsetof (struct dataset
, resp
);
242 dataset
->head
.notfound
= false;
243 dataset
->head
.nreloads
= he
== NULL
? 0 : (dh
->nreloads
+ 1);
244 dataset
->head
.usable
= true;
246 /* Compute the timeout time. */
247 dataset
->head
.timeout
= t
+ db
->postimeout
;
249 dataset
->resp
.version
= NSCD_VERSION
;
250 dataset
->resp
.found
= 1;
251 dataset
->resp
.h_name_len
= h_name_len
;
252 dataset
->resp
.h_aliases_cnt
= h_aliases_cnt
;
253 dataset
->resp
.h_addrtype
= hst
->h_addrtype
;
254 dataset
->resp
.h_length
= hst
->h_length
;
255 dataset
->resp
.h_addr_list_cnt
= h_addr_list_cnt
;
256 dataset
->resp
.error
= NETDB_SUCCESS
;
258 cp
= dataset
->strdata
;
260 cp
= mempcpy (cp
, hst
->h_name
, h_name_len
);
261 cp
= mempcpy (cp
, h_aliases_len
, h_aliases_cnt
* sizeof (uint32_t));
263 /* The normal addresses first. */
265 for (cnt
= 0; cnt
< h_addr_list_cnt
; ++cnt
)
266 cp
= mempcpy (cp
, hst
->h_addr_list
[cnt
], hst
->h_length
);
268 /* Then the aliases. */
270 for (cnt
= 0; cnt
< h_aliases_cnt
; ++cnt
)
271 cp
= mempcpy (cp
, hst
->h_aliases
[cnt
], h_aliases_len
[cnt
]);
274 == dataset
->strdata
+ total
- offsetof (struct dataset
,
277 /* If we are adding a GETHOSTBYNAME{,v6} entry we must be prepared
278 that the answer we get from the NSS does not contain the key
279 itself. This is the case if the resolver is used and the name
280 is extended by the domainnames from /etc/resolv.conf. Therefore
281 we explicitly add the name here. */
282 key_copy
= memcpy (cp
, key
, req
->key_len
);
284 /* Now we can determine whether on refill we have to create a new
290 if (total
+ req
->key_len
== dh
->allocsize
291 && total
- offsetof (struct dataset
, resp
) == dh
->recsize
292 && memcmp (&dataset
->resp
, dh
->data
,
293 dh
->allocsize
- offsetof (struct dataset
, resp
)) == 0)
295 /* The data has not changed. We will just bump the
296 timeout value. Note that the new record has been
297 allocated on the stack and need not be freed. */
298 dh
->timeout
= dataset
->head
.timeout
;
303 /* We have to create a new record. Just allocate
304 appropriate memory and copy it. */
306 = (struct dataset
*) mempool_alloc (db
, total
+ req
->key_len
);
309 /* Adjust pointers into the memory block. */
310 addresses
= (char *) newp
+ (addresses
- (char *) dataset
);
311 aliases
= (char *) newp
+ (aliases
- (char *) dataset
);
312 if (key_copy
!= NULL
)
313 key_copy
= (char *) newp
+ (key_copy
- (char *) dataset
);
315 dataset
= memcpy (newp
, dataset
, total
+ req
->key_len
);
319 /* Mark the old record as obsolete. */
325 /* We write the dataset before inserting it to the database
326 since while inserting this thread might block and so would
327 unnecessarily keep the receiver waiting. */
330 written
= TEMP_FAILURE_RETRY (write (fd
, &dataset
->resp
, total
));
333 /* Add the record to the database. But only if it has not been
336 If the record contains more than one IP address (used for
337 load balancing etc) don't cache the entry. This is something
338 the current cache handling cannot handle and it is more than
339 questionable whether it is worthwhile complicating the cache
340 handling just for handling such a special case. */
343 /* If necessary, we also propagate the data to disk. */
347 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
348 msync ((void *) pval
,
349 ((uintptr_t) dataset
& pagesize_m1
)
350 + total
+ req
->key_len
, MS_ASYNC
);
353 addr_list_type
= (hst
->h_length
== NS_INADDRSZ
354 ? GETHOSTBYADDR
: GETHOSTBYADDRv6
);
356 /* Now get the lock to safely insert the records. */
357 pthread_rwlock_rdlock (&db
->lock
);
359 /* NB: the following code is really complicated. It has
360 seemlingly duplicated code paths which do the same. The
361 problem is that we always must add the hash table entry
362 with the FIRST flag set first. Otherwise we get dangling
363 pointers in case memory allocation fails. */
364 assert (hst
->h_addr_list
[1] == NULL
);
366 /* Avoid adding names if more than one address is available. See
367 above for more info. */
368 assert (req
->type
== GETHOSTBYNAME
369 || req
->type
== GETHOSTBYNAMEv6
370 || req
->type
== GETHOSTBYADDR
371 || req
->type
== GETHOSTBYADDRv6
);
373 if (cache_add (req
->type
, key_copy
, req
->key_len
,
374 &dataset
->head
, true, db
, owner
) < 0)
375 /* Could not allocate memory. Make sure the
376 data gets discarded. */
377 dataset
->head
.usable
= false;
379 pthread_rwlock_unlock (&db
->lock
);
383 if (__builtin_expect (written
!= total
, 0) && debug_level
> 0)
386 dbg_log (_("short write in %s: %s"), __FUNCTION__
,
387 strerror_r (errno
, buf
, sizeof (buf
)));
393 lookup (int type
, void *key
, struct hostent
*resultbufp
, char *buffer
,
394 size_t buflen
, struct hostent
**hst
)
396 if (type
== GETHOSTBYNAME
)
397 return __gethostbyname2_r (key
, AF_INET
, resultbufp
, buffer
, buflen
, hst
,
399 if (type
== GETHOSTBYNAMEv6
)
400 return __gethostbyname2_r (key
, AF_INET6
, resultbufp
, buffer
, buflen
, hst
,
402 if (type
== GETHOSTBYADDR
)
403 return __gethostbyaddr_r (key
, NS_INADDRSZ
, AF_INET
, resultbufp
, buffer
,
404 buflen
, hst
, &h_errno
);
405 return __gethostbyaddr_r (key
, NS_IN6ADDRSZ
, AF_INET6
, resultbufp
, buffer
,
406 buflen
, hst
, &h_errno
);
411 addhstbyX (struct database_dyn
*db
, int fd
, request_header
*req
,
412 void *key
, uid_t uid
, struct hashentry
*he
, struct datahead
*dh
)
414 /* Search for the entry matching the key. Please note that we don't
415 look again in the table whether the dataset is now available. We
416 simply insert it. It does not matter if it is in there twice. The
417 pruning function only will look at the timestamp. */
419 char *buffer
= (char *) alloca (buflen
);
420 struct hostent resultbuf
;
422 bool use_malloc
= false;
425 if (__builtin_expect (debug_level
> 0, 0))
428 char buf
[INET6_ADDRSTRLEN
+ 1];
429 if (req
->type
== GETHOSTBYNAME
|| req
->type
== GETHOSTBYNAMEv6
)
432 str
= inet_ntop (req
->type
== GETHOSTBYADDR
? AF_INET
: AF_INET6
,
433 key
, buf
, sizeof (buf
));
436 dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) str
);
438 dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) str
);
445 oldeuid
= geteuid ();
446 pthread_seteuid_np (uid
);
450 while (lookup (req
->type
, key
, &resultbuf
, buffer
, buflen
, &hst
) != 0
451 && h_errno
== NETDB_INTERNAL
452 && (errval
= errno
) == ERANGE
)
454 char *old_buffer
= buffer
;
458 if (__builtin_expect (buflen
> 32768, 0))
461 buffer
= (char *) realloc (use_malloc
? buffer
: NULL
, buflen
);
464 /* We ran out of memory. We cannot do anything but
465 sending a negative response. In reality this should
470 /* We set the error to indicate this is (possibly) a
471 temporary error and that it does not mean the entry
472 is not available at all. */
479 /* Allocate a new buffer on the stack. If possible combine it
480 with the previously allocated buffer. */
481 buffer
= (char *) extend_alloca (buffer
, buflen
, buflen
+ INCR
);
486 pthread_seteuid_np (oldeuid
);
489 cache_addhst (db
, fd
, req
, key
, hst
, uid
, he
, dh
,
490 h_errno
== TRY_AGAIN
? errval
: 0);
498 addhstbyname (struct database_dyn
*db
, int fd
, request_header
*req
,
499 void *key
, uid_t uid
)
501 addhstbyX (db
, fd
, req
, key
, uid
, NULL
, NULL
);
506 readdhstbyname (struct database_dyn
*db
, struct hashentry
*he
,
511 .type
= GETHOSTBYNAME
,
515 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
520 addhstbyaddr (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 readdhstbyaddr (struct database_dyn
*db
, struct hashentry
*he
,
533 .type
= GETHOSTBYADDR
,
537 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
542 addhstbynamev6 (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 readdhstbynamev6 (struct database_dyn
*db
, struct hashentry
*he
,
555 .type
= GETHOSTBYNAMEv6
,
559 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);
564 addhstbyaddrv6 (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 readdhstbyaddrv6 (struct database_dyn
*db
, struct hashentry
*he
,
577 .type
= GETHOSTBYADDRv6
,
581 addhstbyX (db
, -1, &req
, db
->data
+ he
->key
, he
->owner
, he
, dh
);