1 /* Cache handling for host lookup.
2 Copyright (C) 1998-2008, 2009 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 *const he, struct datahead *dh, int errval,
86 bool all_written = true;
87 time_t t = time (NULL);
89 /* We allocate all data in one memory block: the iov vector,
90 the response header and the dataset itself. */
94 hst_response_header resp;
98 assert (offsetof (struct dataset, resp) == offsetof (struct datahead, data));
102 if (he != NULL && errval == EAGAIN)
104 /* If we have an old record available but cannot find one
105 now because the service is not available we keep the old
106 record and make sure it does not get removed. */
107 if (reload_count != UINT_MAX)
108 /* Do not reset the value if we never not reload the record. */
109 dh->nreloads = reload_count - 1;
113 /* We have no data. This means we send the standard reply for this
115 ssize_t total = sizeof (notfound);
118 TEMP_FAILURE_RETRY (send (fd, ¬found, total,
119 MSG_NOSIGNAL)) != total)
122 dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len,
124 /* If we cannot permanently store the result, so be it. */
127 dataset->head.allocsize = sizeof (struct dataset) + req->key_len;
128 dataset->head.recsize = total;
129 dataset->head.notfound = true;
130 dataset->head.nreloads = 0;
131 dataset->head.usable = true;
133 /* Compute the timeout time. */
134 dataset->head.timeout = t + (ttl == INT32_MAX
135 ? db->negtimeout : ttl);
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 (void) cache_add (req->type, &dataset->strdata, req->key_len,
154 &dataset->head, true, db, owner, he == NULL);
156 /* Mark the old entry as obsolete. */
164 /* Determine the I/O structure. */
165 size_t h_name_len = strlen (hst->h_name) + 1;
166 size_t h_aliases_cnt;
167 uint32_t *h_aliases_len;
168 size_t h_addr_list_cnt;
172 char *key_copy = NULL;
177 /* Determine the number of aliases. */
179 for (cnt = 0; hst->h_aliases[cnt] != NULL; ++cnt)
181 /* Determine the length of all aliases. */
182 h_aliases_len = (uint32_t *) alloca (h_aliases_cnt * sizeof (uint32_t));
184 for (cnt = 0; cnt < h_aliases_cnt; ++cnt)
186 h_aliases_len[cnt] = strlen (hst->h_aliases[cnt]) + 1;
187 total += h_aliases_len[cnt];
190 /* Determine the number of addresses. */
192 while (hst->h_addr_list[h_addr_list_cnt] != NULL)
195 if (h_addr_list_cnt == 0)
199 total += (sizeof (struct dataset)
201 + h_aliases_cnt * sizeof (uint32_t)
202 + h_addr_list_cnt * hst->h_length);
204 /* If we refill the cache, first assume the reconrd did not
205 change. Allocate memory on the cache since it is likely
206 discarded anyway. If it turns out to be necessary to have a
207 new record we can still allocate real memory. */
208 bool alloca_used = false;
211 /* If the record contains more than one IP address (used for
212 load balancing etc) don't cache the entry. This is something
213 the current cache handling cannot handle and it is more than
214 questionable whether it is worthwhile complicating the cache
215 handling just for handling such a special case. */
216 if (he == NULL && h_addr_list_cnt == 1)
217 dataset = (struct dataset *) mempool_alloc (db, total + req->key_len,
222 /* We cannot permanently add the result in the moment. But
223 we can provide the result as is. Store the data in some
225 dataset = (struct dataset *) alloca (total + req->key_len);
227 /* We cannot add this record to the permanent database. */
231 dataset->head.allocsize = total + req->key_len;
232 dataset->head.recsize = total - offsetof (struct dataset, resp);
233 dataset->head.notfound = false;
234 dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1);
235 dataset->head.usable = true;
237 /* Compute the timeout time. */
238 dataset->head.timeout = t + (ttl == INT32_MAX ? db->postimeout : ttl);
240 dataset->resp.version = NSCD_VERSION;
241 dataset->resp.found = 1;
242 dataset->resp.h_name_len = h_name_len;
243 dataset->resp.h_aliases_cnt = h_aliases_cnt;
244 dataset->resp.h_addrtype = hst->h_addrtype;
245 dataset->resp.h_length = hst->h_length;
246 dataset->resp.h_addr_list_cnt = h_addr_list_cnt;
247 dataset->resp.error = NETDB_SUCCESS;
249 /* Make sure there is no gap. */
250 assert ((char *) (&dataset->resp.error + 1) == dataset->strdata);
252 cp = dataset->strdata;
254 cp = mempcpy (cp, hst->h_name, h_name_len);
255 cp = mempcpy (cp, h_aliases_len, h_aliases_cnt * sizeof (uint32_t));
257 /* The normal addresses first. */
259 for (cnt = 0; cnt < h_addr_list_cnt; ++cnt)
260 cp = mempcpy (cp, hst->h_addr_list[cnt], hst->h_length);
262 /* Then the aliases. */
264 for (cnt = 0; cnt < h_aliases_cnt; ++cnt)
265 cp = mempcpy (cp, hst->h_aliases[cnt], h_aliases_len[cnt]);
268 == dataset->strdata + total - offsetof (struct dataset,
271 /* If we are adding a GETHOSTBYNAME{,v6} entry we must be prepared
272 that the answer we get from the NSS does not contain the key
273 itself. This is the case if the resolver is used and the name
274 is extended by the domainnames from /etc/resolv.conf. Therefore
275 we explicitly add the name here. */
276 key_copy = memcpy (cp, key, req->key_len);
278 assert ((char *) &dataset->resp + dataset->head.recsize == cp);
280 /* Now we can determine whether on refill we have to create a new
286 if (total + req->key_len == dh->allocsize
287 && total - offsetof (struct dataset, resp) == dh->recsize
288 && memcmp (&dataset->resp, dh->data,
289 dh->allocsize - offsetof (struct dataset, resp)) == 0)
291 /* The data has not changed. We will just bump the
292 timeout value. Note that the new record has been
293 allocated on the stack and need not be freed. */
294 assert (h_addr_list_cnt == 1);
295 dh->timeout = dataset->head.timeout;
300 if (h_addr_list_cnt == 1)
302 /* We have to create a new record. Just allocate
303 appropriate memory and copy it. */
305 = (struct dataset *) mempool_alloc (db,
306 total + req->key_len,
310 /* Adjust pointers into the memory block. */
311 addresses = (char *) newp + (addresses
313 aliases = (char *) newp + (aliases - (char *) dataset);
314 assert (key_copy != NULL);
315 key_copy = (char *) newp + (key_copy - (char *) dataset);
317 dataset = memcpy (newp, dataset, total + req->key_len);
322 /* Mark the old record as obsolete. */
328 /* We write the dataset before inserting it to the database
329 since while inserting this thread might block and so would
330 unnecessarily keep the receiver waiting. */
334 if (__builtin_expect (db->mmap_used, 1) && !alloca_used)
336 assert (db->wr_fd != -1);
337 assert ((char *) &dataset->resp > (char *) db->data);
338 assert ((char *) &dataset->resp - (char *) db->head
340 <= (sizeof (struct database_pers_head)
341 + db->head->module * sizeof (ref_t)
342 + db->head->data_size));
343 ssize_t written = sendfileall (fd, db->wr_fd,
344 (char *) &dataset->resp
346 dataset->head.recsize);
347 if (written != dataset->head.recsize)
349 # ifndef __ASSUME_SENDFILE
350 if (written == -1 && errno == ENOSYS)
357 # ifndef __ASSUME_SENDFILE
361 if (writeall (fd, &dataset->resp, dataset->head.recsize)
362 != dataset->head.recsize)
366 /* Add the record to the database. But only if it has not been
369 If the record contains more than one IP address (used for
370 load balancing etc) don't cache the entry. This is something
371 the current cache handling cannot handle and it is more than
372 questionable whether it is worthwhile complicating the cache
373 handling just for handling such a special case. */
376 /* If necessary, we also propagate the data to disk. */
380 uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
381 msync ((void *) pval,
382 ((uintptr_t) dataset & pagesize_m1)
383 + total + req->key_len, MS_ASYNC);
386 addr_list_type = (hst->h_length == NS_INADDRSZ
387 ? GETHOSTBYADDR : GETHOSTBYADDRv6);
389 /* NB: the following code is really complicated. It has
390 seemlingly duplicated code paths which do the same. The
391 problem is that we always must add the hash table entry
392 with the FIRST flag set first. Otherwise we get dangling
393 pointers in case memory allocation fails. */
394 assert (hst->h_addr_list[1] == NULL);
396 /* Avoid adding names if more than one address is available. See
397 above for more info. */
398 assert (req->type == GETHOSTBYNAME
399 || req->type == GETHOSTBYNAMEv6
400 || req->type == GETHOSTBYADDR
401 || req->type == GETHOSTBYADDRv6);
403 (void) cache_add (req->type, key_copy, req->key_len,
404 &dataset->head, true, db, owner, he == NULL);
408 if (__builtin_expect (!all_written, 0) && debug_level > 0)
411 dbg_log (_("short write in %s: %s"), __FUNCTION__,
412 strerror_r (errno, buf, sizeof (buf)));
418 lookup (int type, void *key, struct hostent *resultbufp, char *buffer,
419 size_t buflen, struct hostent **hst, int32_t *ttlp)
421 if (type == GETHOSTBYNAME)
422 return __gethostbyname3_r (key, AF_INET, resultbufp, buffer, buflen, hst,
423 &h_errno, ttlp, NULL);
424 if (type == GETHOSTBYNAMEv6)
425 return __gethostbyname3_r (key, AF_INET6, resultbufp, buffer, buflen, hst,
426 &h_errno, ttlp, NULL);
427 if (type == GETHOSTBYADDR)
428 return __gethostbyaddr2_r (key, NS_INADDRSZ, AF_INET, resultbufp, buffer,
429 buflen, hst, &h_errno, ttlp);
430 return __gethostbyaddr2_r (key, NS_IN6ADDRSZ, AF_INET6, resultbufp, buffer,
431 buflen, hst, &h_errno, ttlp);
436 addhstbyX (struct database_dyn *db, int fd, request_header *req,
437 void *key, uid_t uid, struct hashentry *he, struct datahead *dh)
439 /* Search for the entry matching the key. Please note that we don't
440 look again in the table whether the dataset is now available. We
441 simply insert it. It does not matter if it is in there twice. The
442 pruning function only will look at the timestamp. */
444 char *buffer = (char *) alloca (buflen);
445 struct hostent resultbuf;
447 bool use_malloc = false;
449 int32_t ttl = INT32_MAX;
451 if (__builtin_expect (debug_level > 0, 0))
454 char buf[INET6_ADDRSTRLEN + 1];
455 if (req->type == GETHOSTBYNAME || req->type == GETHOSTBYNAMEv6)
458 str = inet_ntop (req->type == GETHOSTBYADDR ? AF_INET : AF_INET6,
459 key, buf, sizeof (buf));
462 dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) str);
464 dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) str);
467 while (lookup (req->type, key, &resultbuf, buffer, buflen, &hst, &ttl) != 0
468 && h_errno == NETDB_INTERNAL
469 && (errval = errno) == ERANGE)
473 if (__builtin_expect (buflen > 32768, 0))
475 char *old_buffer = buffer;
477 buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen);
480 /* We ran out of memory. We cannot do anything but
481 sending a negative response. In reality this should
486 /* We set the error to indicate this is (possibly) a
487 temporary error and that it does not mean the entry
488 is not available at all. */
495 /* Allocate a new buffer on the stack. If possible combine it
496 with the previously allocated buffer. */
497 buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen);
500 cache_addhst (db, fd, req, key, hst, uid, he, dh,
501 h_errno == TRY_AGAIN ? errval : 0, ttl);
509 addhstbyname (struct database_dyn *db, int fd, request_header *req,
510 void *key, uid_t uid)
512 addhstbyX (db, fd, req, key, uid, NULL, NULL);
517 readdhstbyname (struct database_dyn *db, struct hashentry *he,
522 .type = GETHOSTBYNAME,
526 addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
531 addhstbyaddr (struct database_dyn *db, int fd, request_header *req,
532 void *key, uid_t uid)
534 addhstbyX (db, fd, req, key, uid, NULL, NULL);
539 readdhstbyaddr (struct database_dyn *db, struct hashentry *he,
544 .type = GETHOSTBYADDR,
548 addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
553 addhstbynamev6 (struct database_dyn *db, int fd, request_header *req,
554 void *key, uid_t uid)
556 addhstbyX (db, fd, req, key, uid, NULL, NULL);
561 readdhstbynamev6 (struct database_dyn *db, struct hashentry *he,
566 .type = GETHOSTBYNAMEv6,
570 addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
575 addhstbyaddrv6 (struct database_dyn *db, int fd, request_header *req,
576 void *key, uid_t uid)
578 addhstbyX (db, fd, req, key, uid, NULL, NULL);
583 readdhstbyaddrv6 (struct database_dyn *db, struct hashentry *he,
588 .type = GETHOSTBYADDRv6,
592 addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);