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>
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 (send (fd
, ¬found
, total
,
121 dataset
= mempool_alloc (db
, sizeof (struct dataset
) + req
->key_len
);
122 /* If we cannot permanently store the result, so be it. */
125 dataset
->head
.allocsize
= sizeof (struct dataset
) + req
->key_len
;
126 dataset
->head
.recsize
= total
;
127 dataset
->head
.notfound
= true;
128 dataset
->head
.nreloads
= 0;
129 dataset
->head
.usable
= true;
131 /* Compute the timeout time. */
132 dataset
->head
.timeout
= t
+ db
->negtimeout
;
134 /* This is the reply. */
135 memcpy (&dataset
->resp
, ¬found
, total
);
137 /* Copy the key data. */
138 memcpy (dataset
->strdata
, key
, req
->key_len
);
140 /* If necessary, we also propagate the data to disk. */
144 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
145 msync ((void *) pval
,
146 ((uintptr_t) dataset
& pagesize_m1
)
147 + sizeof (struct dataset
) + req
->key_len
, MS_ASYNC
);
150 /* Now get the lock to safely insert the records. */
151 pthread_rwlock_rdlock (&db
->lock
);
153 if (cache_add (req
->type
, &dataset
->strdata
, req
->key_len
,
154 &dataset
->head
, true, db
, owner
) < 0)
155 /* Ensure the data can be recovered. */
156 dataset
->head
.usable
= false;
158 pthread_rwlock_unlock (&db
->lock
);
160 /* Mark the old entry as obsolete. */
165 ++db
->head
->addfailed
;
170 /* Determine the I/O structure. */
171 size_t h_name_len
= strlen (hst
->h_name
) + 1;
172 size_t h_aliases_cnt
;
173 uint32_t *h_aliases_len
;
174 size_t h_addr_list_cnt
;
178 char *key_copy
= NULL
;
182 /* Determine the number of aliases. */
184 for (cnt
= 0; hst
->h_aliases
[cnt
] != NULL
; ++cnt
)
186 /* Determine the length of all aliases. */
187 h_aliases_len
= (uint32_t *) alloca (h_aliases_cnt
* sizeof (uint32_t));
189 for (cnt
= 0; cnt
< h_aliases_cnt
; ++cnt
)
191 h_aliases_len
[cnt
] = strlen (hst
->h_aliases
[cnt
]) + 1;
192 total
+= h_aliases_len
[cnt
];
195 /* Determine the number of addresses. */
197 for (cnt
= 0; hst
->h_addr_list
[cnt
]; ++cnt
)
200 if (h_addr_list_cnt
== 0)
204 total
+= (sizeof (struct dataset
)
206 + h_aliases_cnt
* sizeof (uint32_t)
207 + h_addr_list_cnt
* hst
->h_length
);
210 /* If we refill the cache, first assume the reconrd did not
211 change. Allocate memory on the cache since it is likely
212 discarded anyway. If it turns out to be necessary to have a
213 new record we can still allocate real memory. */
214 bool alloca_used
= false;
217 /* If the record contains more than one IP address (used for
218 load balancing etc) don't cache the entry. This is something
219 the current cache handling cannot handle and it is more than
220 questionable whether it is worthwhile complicating the cache
221 handling just for handling such a special case. */
222 if (he
== NULL
&& hst
->h_addr_list
[1] == NULL
)
224 dataset
= (struct dataset
*) mempool_alloc (db
,
225 total
+ req
->key_len
);
227 ++db
->head
->addfailed
;
232 /* We cannot permanently add the result in the moment. But
233 we can provide the result as is. Store the data in some
235 dataset
= (struct dataset
*) alloca (total
+ req
->key_len
);
237 /* We cannot add this record to the permanent database. */
241 dataset
->head
.allocsize
= total
+ req
->key_len
;
242 dataset
->head
.recsize
= total
- offsetof (struct dataset
, resp
);
243 dataset
->head
.notfound
= false;
244 dataset
->head
.nreloads
= he
== NULL
? 0 : (dh
->nreloads
+ 1);
245 dataset
->head
.usable
= true;
247 /* Compute the timeout time. */
248 dataset
->head
.timeout
= t
+ db
->postimeout
;
250 dataset
->resp
.version
= NSCD_VERSION
;
251 dataset
->resp
.found
= 1;
252 dataset
->resp
.h_name_len
= h_name_len
;
253 dataset
->resp
.h_aliases_cnt
= h_aliases_cnt
;
254 dataset
->resp
.h_addrtype
= hst
->h_addrtype
;
255 dataset
->resp
.h_length
= hst
->h_length
;
256 dataset
->resp
.h_addr_list_cnt
= h_addr_list_cnt
;
257 dataset
->resp
.error
= NETDB_SUCCESS
;
259 cp
= dataset
->strdata
;
261 cp
= mempcpy (cp
, hst
->h_name
, h_name_len
);
262 cp
= mempcpy (cp
, h_aliases_len
, h_aliases_cnt
* sizeof (uint32_t));
264 /* The normal addresses first. */
266 for (cnt
= 0; cnt
< h_addr_list_cnt
; ++cnt
)
267 cp
= mempcpy (cp
, hst
->h_addr_list
[cnt
], hst
->h_length
);
269 /* Then the aliases. */
271 for (cnt
= 0; cnt
< h_aliases_cnt
; ++cnt
)
272 cp
= mempcpy (cp
, hst
->h_aliases
[cnt
], h_aliases_len
[cnt
]);
275 == dataset
->strdata
+ total
- offsetof (struct dataset
,
278 /* If we are adding a GETHOSTBYNAME{,v6} entry we must be prepared
279 that the answer we get from the NSS does not contain the key
280 itself. This is the case if the resolver is used and the name
281 is extended by the domainnames from /etc/resolv.conf. Therefore
282 we explicitly add the name here. */
283 key_copy
= memcpy (cp
, key
, req
->key_len
);
285 /* Now we can determine whether on refill we have to create a new
291 if (total
+ req
->key_len
== dh
->allocsize
292 && total
- offsetof (struct dataset
, resp
) == dh
->recsize
293 && memcmp (&dataset
->resp
, dh
->data
,
294 dh
->allocsize
- offsetof (struct dataset
, resp
)) == 0)
296 /* The data has not changed. We will just bump the
297 timeout value. Note that the new record has been
298 allocated on the stack and need not be freed. */
299 dh
->timeout
= dataset
->head
.timeout
;
304 /* We have to create a new record. Just allocate
305 appropriate memory and copy it. */
307 = (struct dataset
*) mempool_alloc (db
, total
+ req
->key_len
);
310 /* Adjust pointers into the memory block. */
311 addresses
= (char *) newp
+ (addresses
- (char *) dataset
);
312 aliases
= (char *) newp
+ (aliases
- (char *) dataset
);
313 if (key_copy
!= NULL
)
314 key_copy
= (char *) newp
+ (key_copy
- (char *) dataset
);
316 dataset
= memcpy (newp
, dataset
, total
+ req
->key_len
);
320 /* Mark the old record as obsolete. */
326 /* We write the dataset before inserting it to the database
327 since while inserting this thread might block and so would
328 unnecessarily keep the receiver waiting. */
331 written
= writeall (fd
, &dataset
->resp
, total
);
334 /* Add the record to the database. But only if it has not been
337 If the record contains more than one IP address (used for
338 load balancing etc) don't cache the entry. This is something
339 the current cache handling cannot handle and it is more than
340 questionable whether it is worthwhile complicating the cache
341 handling just for handling such a special case. */
344 /* If necessary, we also propagate the data to disk. */
348 uintptr_t pval
= (uintptr_t) dataset
& ~pagesize_m1
;
349 msync ((void *) pval
,
350 ((uintptr_t) dataset
& pagesize_m1
)
351 + total
+ req
->key_len
, MS_ASYNC
);
354 addr_list_type
= (hst
->h_length
== NS_INADDRSZ
355 ? GETHOSTBYADDR
: GETHOSTBYADDRv6
);
357 /* Now get the lock to safely insert the records. */
358 pthread_rwlock_rdlock (&db
->lock
);
360 /* NB: the following code is really complicated. It has
361 seemlingly duplicated code paths which do the same. The
362 problem is that we always must add the hash table entry
363 with the FIRST flag set first. Otherwise we get dangling
364 pointers in case memory allocation fails. */
365 assert (hst
->h_addr_list
[1] == NULL
);
367 /* Avoid adding names if more than one address is available. See
368 above for more info. */
369 assert (req
->type
== GETHOSTBYNAME
370 || req
->type
== GETHOSTBYNAMEv6
371 || req
->type
== GETHOSTBYADDR
372 || req
->type
== GETHOSTBYADDRv6
);
374 if (cache_add (req
->type
, key_copy
, req
->key_len
,
375 &dataset
->head
, true, db
, owner
) < 0)
376 /* Could not allocate memory. Make sure the
377 data gets discarded. */
378 dataset
->head
.usable
= false;
380 pthread_rwlock_unlock (&db
->lock
);
384 if (__builtin_expect (written
!= total
, 0) && debug_level
> 0)
387 dbg_log (_("short write in %s: %s"), __FUNCTION__
,
388 strerror_r (errno
, buf
, sizeof (buf
)));
394 lookup (int type
, void *key
, struct hostent
*resultbufp
, char *buffer
,
395 size_t buflen
, struct hostent
**hst
)
397 if (type
== GETHOSTBYNAME
)
398 return __gethostbyname2_r (key
, AF_INET
, resultbufp
, buffer
, buflen
, hst
,
400 if (type
== GETHOSTBYNAMEv6
)
401 return __gethostbyname2_r (key
, AF_INET6
, resultbufp
, buffer
, buflen
, hst
,
403 if (type
== GETHOSTBYADDR
)
404 return __gethostbyaddr_r (key
, NS_INADDRSZ
, AF_INET
, resultbufp
, buffer
,
405 buflen
, hst
, &h_errno
);
406 return __gethostbyaddr_r (key
, NS_IN6ADDRSZ
, AF_INET6
, resultbufp
, buffer
,
407 buflen
, hst
, &h_errno
);
412 addhstbyX (struct database_dyn
*db
, int fd
, request_header
*req
,
413 void *key
, uid_t uid
, struct hashentry
*he
, struct datahead
*dh
)
415 /* Search for the entry matching the key. Please note that we don't
416 look again in the table whether the dataset is now available. We
417 simply insert it. It does not matter if it is in there twice. The
418 pruning function only will look at the timestamp. */
420 char *buffer
= (char *) alloca (buflen
);
421 struct hostent resultbuf
;
423 bool use_malloc
= false;
426 if (__builtin_expect (debug_level
> 0, 0))
429 char buf
[INET6_ADDRSTRLEN
+ 1];
430 if (req
->type
== GETHOSTBYNAME
|| req
->type
== GETHOSTBYNAMEv6
)
433 str
= inet_ntop (req
->type
== GETHOSTBYADDR
? AF_INET
: AF_INET6
,
434 key
, buf
, sizeof (buf
));
437 dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) str
);
439 dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) str
);
446 oldeuid
= geteuid ();
447 pthread_seteuid_np (uid
);
451 while (lookup (req
->type
, key
, &resultbuf
, buffer
, buflen
, &hst
) != 0
452 && h_errno
== NETDB_INTERNAL
453 && (errval
= errno
) == ERANGE
)
455 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
, 2 * buflen
);
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
);