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);
330 /* Mark the old record as obsolete. */
336 /* We write the dataset before inserting it to the database
337 since while inserting this thread might block and so would
338 unnecessarily keep the receiver waiting. */
342 if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
344 assert (db->wr_fd != -1);
345 assert ((char *) &dataset->resp > (char *) db->data);
346 assert ((char *) &dataset->resp - (char *) db->head
348 <= (sizeof (struct database_pers_head)
349 + db->head->module * sizeof (ref_t)
350 + db->head->data_size));
351 written = sendfileall (fd, db->wr_fd,
352 (char *) &dataset->resp
353 - (char *) db->head, total);
354 # ifndef __ASSUME_SENDFILE
355 if (written == -1 && errno == ENOSYS)
360 # ifndef __ASSUME_SENDFILE
364 written = writeall (fd, &dataset->resp, total);
367 /* Add the record to the database. But only if it has not been
370 If the record contains more than one IP address (used for
371 load balancing etc) don't cache the entry. This is something
372 the current cache handling cannot handle and it is more than
373 questionable whether it is worthwhile complicating the cache
374 handling just for handling such a special case. */
377 /* If necessary, we also propagate the data to disk. */
381 uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
382 msync ((void *) pval,
383 ((uintptr_t) dataset & pagesize_m1)
384 + total + req->key_len, MS_ASYNC);
387 addr_list_type = (hst->h_length == NS_INADDRSZ
388 ? GETHOSTBYADDR : GETHOSTBYADDRv6);
390 /* Now get the lock to safely insert the records. */
391 pthread_rwlock_rdlock (&db->lock);
393 /* NB: the following code is really complicated. It has
394 seemlingly duplicated code paths which do the same. The
395 problem is that we always must add the hash table entry
396 with the FIRST flag set first. Otherwise we get dangling
397 pointers in case memory allocation fails. */
398 assert (hst->h_addr_list[1] == NULL);
400 /* Avoid adding names if more than one address is available. See
401 above for more info. */
402 assert (req->type == GETHOSTBYNAME
403 || req->type == GETHOSTBYNAMEv6
404 || req->type == GETHOSTBYADDR
405 || req->type == GETHOSTBYADDRv6);
407 if (cache_add (req->type, key_copy, req->key_len,
408 &dataset->head, true, db, owner) < 0)
409 /* Could not allocate memory. Make sure the
410 data gets discarded. */
411 dataset->head.usable = false;
413 pthread_rwlock_unlock (&db->lock);
417 if (__builtin_expect (written != total, 0) && debug_level > 0)
420 dbg_log (_("short write in %s: %s"), __FUNCTION__,
421 strerror_r (errno, buf, sizeof (buf)));
427 lookup (int type, void *key, struct hostent *resultbufp, char *buffer,
428 size_t buflen, struct hostent **hst, int32_t *ttlp)
430 if (type == GETHOSTBYNAME)
431 return __gethostbyname3_r (key, AF_INET, resultbufp, buffer, buflen, hst,
432 &h_errno, ttlp, NULL);
433 if (type == GETHOSTBYNAMEv6)
434 return __gethostbyname3_r (key, AF_INET6, resultbufp, buffer, buflen, hst,
435 &h_errno, ttlp, NULL);
436 if (type == GETHOSTBYADDR)
437 return __gethostbyaddr2_r (key, NS_INADDRSZ, AF_INET, resultbufp, buffer,
438 buflen, hst, &h_errno, ttlp);
439 return __gethostbyaddr2_r (key, NS_IN6ADDRSZ, AF_INET6, resultbufp, buffer,
440 buflen, hst, &h_errno, ttlp);
445 addhstbyX (struct database_dyn *db, int fd, request_header *req,
446 void *key, uid_t uid, struct hashentry *he, struct datahead *dh)
448 /* Search for the entry matching the key. Please note that we don't
449 look again in the table whether the dataset is now available. We
450 simply insert it. It does not matter if it is in there twice. The
451 pruning function only will look at the timestamp. */
453 char *buffer = (char *) alloca (buflen);
454 struct hostent resultbuf;
456 bool use_malloc = false;
458 int32_t ttl = INT32_MAX;
460 if (__builtin_expect (debug_level > 0, 0))
463 char buf[INET6_ADDRSTRLEN + 1];
464 if (req->type == GETHOSTBYNAME || req->type == GETHOSTBYNAMEv6)
467 str = inet_ntop (req->type == GETHOSTBYADDR ? AF_INET : AF_INET6,
468 key, buf, sizeof (buf));
471 dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) str);
473 dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) str);
476 while (lookup (req->type, key, &resultbuf, buffer, buflen, &hst, &ttl) != 0
477 && h_errno == NETDB_INTERNAL
478 && (errval = errno) == ERANGE)
482 if (__builtin_expect (buflen > 32768, 0))
484 char *old_buffer = buffer;
486 buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen);
489 /* We ran out of memory. We cannot do anything but
490 sending a negative response. In reality this should
495 /* We set the error to indicate this is (possibly) a
496 temporary error and that it does not mean the entry
497 is not available at all. */
504 /* Allocate a new buffer on the stack. If possible combine it
505 with the previously allocated buffer. */
506 buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen);
509 cache_addhst (db, fd, req, key, hst, uid, he, dh,
510 h_errno == TRY_AGAIN ? errval : 0, ttl);
518 addhstbyname (struct database_dyn *db, int fd, request_header *req,
519 void *key, uid_t uid)
521 addhstbyX (db, fd, req, key, uid, NULL, NULL);
526 readdhstbyname (struct database_dyn *db, struct hashentry *he,
531 .type = GETHOSTBYNAME,
535 addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
540 addhstbyaddr (struct database_dyn *db, int fd, request_header *req,
541 void *key, uid_t uid)
543 addhstbyX (db, fd, req, key, uid, NULL, NULL);
548 readdhstbyaddr (struct database_dyn *db, struct hashentry *he,
553 .type = GETHOSTBYADDR,
557 addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
562 addhstbynamev6 (struct database_dyn *db, int fd, request_header *req,
563 void *key, uid_t uid)
565 addhstbyX (db, fd, req, key, uid, NULL, NULL);
570 readdhstbynamev6 (struct database_dyn *db, struct hashentry *he,
575 .type = GETHOSTBYNAMEv6,
579 addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
584 addhstbyaddrv6 (struct database_dyn *db, int fd, request_header *req,
585 void *key, uid_t uid)
587 addhstbyX (db, fd, req, key, uid, NULL, NULL);
592 readdhstbyaddrv6 (struct database_dyn *db, struct hashentry *he,
597 .type = GETHOSTBYADDRv6,
601 addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);