1 /* Cache handling for services lookup.
2 Copyright (C) 2007-2019 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@drepper.com>, 2007.
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, see <https://www.gnu.org/licenses/>. */
26 #include <kernel-features.h>
27 #include <scratch_buffer.h>
33 /* This is the standard reply in case the service is disabled. */
34 static const serv_response_header disabled =
36 .version = NSCD_VERSION,
44 /* This is the struct describing how to write this record. */
45 const struct iovec serv_iov_disabled =
47 .iov_base = (void *) &disabled,
48 .iov_len = sizeof (disabled)
52 /* This is the standard reply in case we haven't found the dataset. */
53 static const serv_response_header notfound =
55 .version = NSCD_VERSION,
65 cache_addserv (struct database_dyn *db, int fd, request_header *req,
66 const void *key, struct servent *serv, uid_t owner,
67 struct hashentry *const he, struct datahead *dh, int errval)
69 bool all_written = true;
71 time_t t = time (NULL);
73 /* We allocate all data in one memory block: the iov vector,
74 the response header and the dataset itself. */
78 serv_response_header resp;
82 assert (offsetof (struct dataset, resp) == offsetof (struct datahead, data));
84 time_t timeout = MAX_TIMEOUT_VALUE;
87 if (he != NULL && errval == EAGAIN)
89 /* If we have an old record available but cannot find one
90 now because the service is not available we keep the old
91 record and make sure it does not get removed. */
92 if (reload_count != UINT_MAX)
93 /* Do not reset the value if we never not reload the record. */
94 dh->nreloads = reload_count - 1;
96 /* Reload with the same time-to-live value. */
97 timeout = dh->timeout = t + db->postimeout;
103 /* We have no data. This means we send the standard reply for this
105 total = sizeof (notfound);
108 && TEMP_FAILURE_RETRY (send (fd, ¬found, total,
109 MSG_NOSIGNAL)) != total)
112 /* If we have a transient error or cannot permanently store
113 the result, so be it. */
114 if (errval == EAGAIN || __builtin_expect (db->negtimeout == 0, 0))
116 /* Mark the old entry as obsolete. */
120 else if ((dataset = mempool_alloc (db, (sizeof (struct dataset)
121 + req->key_len), 1)) != NULL)
123 timeout = datahead_init_neg (&dataset->head,
124 (sizeof (struct dataset)
125 + req->key_len), total,
128 /* This is the reply. */
129 memcpy (&dataset->resp, ¬found, total);
131 /* Copy the key data. */
132 memcpy (dataset->strdata, key, req->key_len);
134 /* If necessary, we also propagate the data to disk. */
138 uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
139 msync ((void *) pval,
140 ((uintptr_t) dataset & pagesize_m1)
141 + sizeof (struct dataset) + req->key_len, MS_ASYNC);
144 (void) cache_add (req->type, &dataset->strdata, req->key_len,
145 &dataset->head, true, db, owner, he == NULL);
147 pthread_rwlock_unlock (&db->lock);
149 /* Mark the old entry as obsolete. */
157 /* Determine the I/O structure. */
158 size_t s_name_len = strlen (serv->s_name) + 1;
159 size_t s_proto_len = strlen (serv->s_proto) + 1;
160 uint32_t *s_aliases_len;
161 size_t s_aliases_cnt;
166 /* Determine the number of aliases. */
168 for (cnt = 0; serv->s_aliases[cnt] != NULL; ++cnt)
170 /* Determine the length of all aliases. */
171 s_aliases_len = (uint32_t *) alloca (s_aliases_cnt * sizeof (uint32_t));
173 for (cnt = 0; cnt < s_aliases_cnt; ++cnt)
175 s_aliases_len[cnt] = strlen (serv->s_aliases[cnt]) + 1;
176 total += s_aliases_len[cnt];
179 total += (offsetof (struct dataset, strdata)
182 + s_aliases_cnt * sizeof (uint32_t));
184 /* If we refill the cache, first assume the reconrd did not
185 change. Allocate memory on the cache since it is likely
186 discarded anyway. If it turns out to be necessary to have a
187 new record we can still allocate real memory. */
188 bool alloca_used = false;
192 dataset = (struct dataset *) mempool_alloc (db, total + req->key_len,
197 /* We cannot permanently add the result in the moment. But
198 we can provide the result as is. Store the data in some
200 dataset = (struct dataset *) alloca (total + req->key_len);
202 /* We cannot add this record to the permanent database. */
206 timeout = datahead_init_pos (&dataset->head, total + req->key_len,
207 total - offsetof (struct dataset, resp),
208 he == NULL ? 0 : dh->nreloads + 1,
211 dataset->resp.version = NSCD_VERSION;
212 dataset->resp.found = 1;
213 dataset->resp.s_name_len = s_name_len;
214 dataset->resp.s_proto_len = s_proto_len;
215 dataset->resp.s_port = serv->s_port;
216 dataset->resp.s_aliases_cnt = s_aliases_cnt;
218 cp = dataset->strdata;
220 cp = mempcpy (cp, serv->s_name, s_name_len);
221 cp = mempcpy (cp, serv->s_proto, s_proto_len);
222 cp = mempcpy (cp, s_aliases_len, s_aliases_cnt * sizeof (uint32_t));
224 /* Then the aliases. */
226 for (cnt = 0; cnt < s_aliases_cnt; ++cnt)
227 cp = mempcpy (cp, serv->s_aliases[cnt], s_aliases_len[cnt]);
230 == dataset->strdata + total - offsetof (struct dataset,
233 char *key_copy = memcpy (cp, key, req->key_len);
235 /* Now we can determine whether on refill we have to create a new
241 if (total + req->key_len == dh->allocsize
242 && total - offsetof (struct dataset, resp) == dh->recsize
243 && memcmp (&dataset->resp, dh->data,
244 dh->allocsize - offsetof (struct dataset, resp)) == 0)
246 /* The data has not changed. We will just bump the
247 timeout value. Note that the new record has been
248 allocated on the stack and need not be freed. */
249 dh->timeout = dataset->head.timeout;
254 /* We have to create a new record. Just allocate
255 appropriate memory and copy it. */
257 = (struct dataset *) mempool_alloc (db, total + req->key_len,
261 /* Adjust pointers into the memory block. */
262 aliases = (char *) newp + (aliases - (char *) dataset);
263 assert (key_copy != NULL);
264 key_copy = (char *) newp + (key_copy - (char *) dataset);
266 dataset = memcpy (newp, dataset, total + req->key_len);
270 /* Mark the old record as obsolete. */
276 /* We write the dataset before inserting it to the database
277 since while inserting this thread might block and so would
278 unnecessarily keep the receiver waiting. */
281 if (writeall (fd, &dataset->resp, dataset->head.recsize)
282 != dataset->head.recsize)
286 /* Add the record to the database. But only if it has not been
287 stored on the stack. */
290 /* If necessary, we also propagate the data to disk. */
294 uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1;
295 msync ((void *) pval,
296 ((uintptr_t) dataset & pagesize_m1)
297 + total + req->key_len, MS_ASYNC);
300 (void) cache_add (req->type, key_copy, req->key_len,
301 &dataset->head, true, db, owner, he == NULL);
303 pthread_rwlock_unlock (&db->lock);
307 if (__builtin_expect (!all_written, 0) && debug_level > 0)
310 dbg_log (_("short write in %s: %s"), __FUNCTION__,
311 strerror_r (errno, buf, sizeof (buf)));
319 lookup (int type, char *key, struct servent *resultbufp, char *buffer,
320 size_t buflen, struct servent **serv)
322 char *proto = strrchr (key, '/');
323 if (proto != NULL && proto != key)
325 key = strndupa (key, proto - key);
326 if (proto[1] == '\0')
332 if (type == GETSERVBYNAME)
333 return __getservbyname_r (key, proto, resultbufp, buffer, buflen, serv);
335 assert (type == GETSERVBYPORT);
336 return __getservbyport_r (atol (key), proto, resultbufp, buffer, buflen,
342 addservbyX (struct database_dyn *db, int fd, request_header *req,
343 char *key, uid_t uid, struct hashentry *he, struct datahead *dh)
345 /* Search for the entry matching the key. Please note that we don't
346 look again in the table whether the dataset is now available. We
347 simply insert it. It does not matter if it is in there twice. The
348 pruning function only will look at the timestamp. */
349 struct servent resultbuf;
350 struct servent *serv;
352 struct scratch_buffer tmpbuf;
353 scratch_buffer_init (&tmpbuf);
355 if (__glibc_unlikely (debug_level > 0))
358 dbg_log (_("Haven't found \"%s\" in services cache!"), key);
360 dbg_log (_("Reloading \"%s\" in services cache!"), key);
363 while (lookup (req->type, key, &resultbuf,
364 tmpbuf.data, tmpbuf.length, &serv) != 0
365 && (errval = errno) == ERANGE)
366 if (!scratch_buffer_grow (&tmpbuf))
368 /* We ran out of memory. We cannot do anything but sending a
369 negative response. In reality this should never
372 /* We set the error to indicate this is (possibly) a temporary
373 error and that it does not mean the entry is not available
379 time_t timeout = cache_addserv (db, fd, req, key, serv, uid, he, dh, errval);
380 scratch_buffer_free (&tmpbuf);
386 addservbyname (struct database_dyn *db, int fd, request_header *req,
387 void *key, uid_t uid)
389 addservbyX (db, fd, req, key, uid, NULL, NULL);
394 readdservbyname (struct database_dyn *db, struct hashentry *he,
399 .type = GETSERVBYNAME,
403 return addservbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
408 addservbyport (struct database_dyn *db, int fd, request_header *req,
409 void *key, uid_t uid)
411 addservbyX (db, fd, req, key, uid, NULL, NULL);
416 readdservbyport (struct database_dyn *db, struct hashentry *he,
421 .type = GETSERVBYPORT,
425 return addservbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);