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b21fa963 | 1 | /* Cache handling for services lookup. |
568035b7 | 2 | Copyright (C) 2007-2013 Free Software Foundation, Inc. |
b21fa963 UD |
3 | This file is part of the GNU C Library. |
4 | Contributed by Ulrich Drepper <drepper@drepper.com>, 2007. | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
2e2efe65 RM |
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. | |
b21fa963 UD |
10 | |
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. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
59ba27a6 | 17 | along with this program; if not, see <http://www.gnu.org/licenses/>. */ |
b21fa963 UD |
18 | |
19 | #include <alloca.h> | |
20 | #include <assert.h> | |
21 | #include <errno.h> | |
22 | #include <libintl.h> | |
23 | #include <netdb.h> | |
24 | #include <unistd.h> | |
25 | #include <sys/mman.h> | |
f8de5057 | 26 | #include <kernel-features.h> |
b21fa963 UD |
27 | |
28 | #include "nscd.h" | |
29 | #include "dbg_log.h" | |
30 | ||
31 | ||
32 | /* This is the standard reply in case the service is disabled. */ | |
33 | static const serv_response_header disabled = | |
34 | { | |
35 | .version = NSCD_VERSION, | |
36 | .found = -1, | |
37 | .s_name_len = 0, | |
38 | .s_proto_len = 0, | |
39 | .s_aliases_cnt = 0, | |
40 | .s_port = -1 | |
41 | }; | |
42 | ||
43 | /* This is the struct describing how to write this record. */ | |
44 | const struct iovec serv_iov_disabled = | |
45 | { | |
46 | .iov_base = (void *) &disabled, | |
47 | .iov_len = sizeof (disabled) | |
48 | }; | |
49 | ||
50 | ||
51 | /* This is the standard reply in case we haven't found the dataset. */ | |
52 | static const serv_response_header notfound = | |
53 | { | |
54 | .version = NSCD_VERSION, | |
55 | .found = 0, | |
56 | .s_name_len = 0, | |
57 | .s_proto_len = 0, | |
58 | .s_aliases_cnt = 0, | |
59 | .s_port = -1 | |
60 | }; | |
61 | ||
62 | ||
a4c7ea7b | 63 | static time_t |
b21fa963 UD |
64 | cache_addserv (struct database_dyn *db, int fd, request_header *req, |
65 | const void *key, struct servent *serv, uid_t owner, | |
20e498bd | 66 | struct hashentry *const he, struct datahead *dh, int errval) |
b21fa963 | 67 | { |
306dfba9 | 68 | bool all_written = true; |
b21fa963 | 69 | ssize_t total; |
b21fa963 UD |
70 | time_t t = time (NULL); |
71 | ||
72 | /* We allocate all data in one memory block: the iov vector, | |
73 | the response header and the dataset itself. */ | |
74 | struct dataset | |
75 | { | |
76 | struct datahead head; | |
77 | serv_response_header resp; | |
78 | char strdata[0]; | |
79 | } *dataset; | |
80 | ||
81 | assert (offsetof (struct dataset, resp) == offsetof (struct datahead, data)); | |
82 | ||
a4c7ea7b | 83 | time_t timeout = MAX_TIMEOUT_VALUE; |
b21fa963 UD |
84 | if (serv == NULL) |
85 | { | |
86 | if (he != NULL && errval == EAGAIN) | |
87 | { | |
88 | /* If we have an old record available but cannot find one | |
89 | now because the service is not available we keep the old | |
90 | record and make sure it does not get removed. */ | |
91 | if (reload_count != UINT_MAX) | |
92 | /* Do not reset the value if we never not reload the record. */ | |
93 | dh->nreloads = reload_count - 1; | |
94 | ||
a4c7ea7b UD |
95 | /* Reload with the same time-to-live value. */ |
96 | timeout = dh->timeout = t + db->postimeout; | |
97 | ||
306dfba9 | 98 | total = 0; |
b21fa963 UD |
99 | } |
100 | else | |
101 | { | |
102 | /* We have no data. This means we send the standard reply for this | |
103 | case. */ | |
306dfba9 | 104 | total = sizeof (notfound); |
b21fa963 | 105 | |
306dfba9 AS |
106 | if (fd != -1 |
107 | && TEMP_FAILURE_RETRY (send (fd, ¬found, total, | |
108 | MSG_NOSIGNAL)) != total) | |
109 | all_written = false; | |
b21fa963 | 110 | |
3e1aa84e UD |
111 | /* If we have a transient error or cannot permanently store |
112 | the result, so be it. */ | |
113 | if (errval == EAGAIN || __builtin_expect (db->negtimeout == 0, 0)) | |
99231d9a UD |
114 | { |
115 | /* Mark the old entry as obsolete. */ | |
116 | if (dh != NULL) | |
117 | dh->usable = false; | |
118 | } | |
119 | else if ((dataset = mempool_alloc (db, (sizeof (struct dataset) | |
120 | + req->key_len), 1)) != NULL) | |
b21fa963 UD |
121 | { |
122 | dataset->head.allocsize = sizeof (struct dataset) + req->key_len; | |
123 | dataset->head.recsize = total; | |
124 | dataset->head.notfound = true; | |
125 | dataset->head.nreloads = 0; | |
126 | dataset->head.usable = true; | |
127 | ||
128 | /* Compute the timeout time. */ | |
a4c7ea7b | 129 | timeout = dataset->head.timeout = t + db->negtimeout; |
b21fa963 UD |
130 | |
131 | /* This is the reply. */ | |
132 | memcpy (&dataset->resp, ¬found, total); | |
133 | ||
134 | /* Copy the key data. */ | |
135 | memcpy (dataset->strdata, key, req->key_len); | |
136 | ||
137 | /* If necessary, we also propagate the data to disk. */ | |
138 | if (db->persistent) | |
139 | { | |
140 | // XXX async OK? | |
141 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; | |
142 | msync ((void *) pval, | |
143 | ((uintptr_t) dataset & pagesize_m1) | |
144 | + sizeof (struct dataset) + req->key_len, MS_ASYNC); | |
145 | } | |
146 | ||
7e71e55f | 147 | (void) cache_add (req->type, &dataset->strdata, req->key_len, |
528741cb | 148 | &dataset->head, true, db, owner, he == NULL); |
b21fa963 | 149 | |
00ebd7ed UD |
150 | pthread_rwlock_unlock (&db->lock); |
151 | ||
b21fa963 UD |
152 | /* Mark the old entry as obsolete. */ |
153 | if (dh != NULL) | |
154 | dh->usable = false; | |
155 | } | |
b21fa963 UD |
156 | } |
157 | } | |
158 | else | |
159 | { | |
160 | /* Determine the I/O structure. */ | |
161 | size_t s_name_len = strlen (serv->s_name) + 1; | |
162 | size_t s_proto_len = strlen (serv->s_proto) + 1; | |
163 | uint32_t *s_aliases_len; | |
164 | size_t s_aliases_cnt; | |
165 | char *aliases; | |
166 | char *cp; | |
167 | size_t cnt; | |
168 | ||
169 | /* Determine the number of aliases. */ | |
170 | s_aliases_cnt = 0; | |
171 | for (cnt = 0; serv->s_aliases[cnt] != NULL; ++cnt) | |
172 | ++s_aliases_cnt; | |
173 | /* Determine the length of all aliases. */ | |
174 | s_aliases_len = (uint32_t *) alloca (s_aliases_cnt * sizeof (uint32_t)); | |
175 | total = 0; | |
176 | for (cnt = 0; cnt < s_aliases_cnt; ++cnt) | |
177 | { | |
178 | s_aliases_len[cnt] = strlen (serv->s_aliases[cnt]) + 1; | |
179 | total += s_aliases_len[cnt]; | |
180 | } | |
181 | ||
5a337776 | 182 | total += (offsetof (struct dataset, strdata) |
b21fa963 UD |
183 | + s_name_len |
184 | + s_proto_len | |
185 | + s_aliases_cnt * sizeof (uint32_t)); | |
b21fa963 UD |
186 | |
187 | /* If we refill the cache, first assume the reconrd did not | |
188 | change. Allocate memory on the cache since it is likely | |
189 | discarded anyway. If it turns out to be necessary to have a | |
190 | new record we can still allocate real memory. */ | |
191 | bool alloca_used = false; | |
192 | dataset = NULL; | |
193 | ||
194 | if (he == NULL) | |
20e498bd UD |
195 | dataset = (struct dataset *) mempool_alloc (db, total + req->key_len, |
196 | 1); | |
b21fa963 UD |
197 | |
198 | if (dataset == NULL) | |
199 | { | |
200 | /* We cannot permanently add the result in the moment. But | |
201 | we can provide the result as is. Store the data in some | |
202 | temporary memory. */ | |
203 | dataset = (struct dataset *) alloca (total + req->key_len); | |
204 | ||
205 | /* We cannot add this record to the permanent database. */ | |
206 | alloca_used = true; | |
207 | } | |
208 | ||
209 | dataset->head.allocsize = total + req->key_len; | |
210 | dataset->head.recsize = total - offsetof (struct dataset, resp); | |
211 | dataset->head.notfound = false; | |
212 | dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1); | |
213 | dataset->head.usable = true; | |
214 | ||
215 | /* Compute the timeout time. */ | |
a4c7ea7b | 216 | timeout = dataset->head.timeout = t + db->postimeout; |
b21fa963 UD |
217 | |
218 | dataset->resp.version = NSCD_VERSION; | |
219 | dataset->resp.found = 1; | |
220 | dataset->resp.s_name_len = s_name_len; | |
221 | dataset->resp.s_proto_len = s_proto_len; | |
222 | dataset->resp.s_port = serv->s_port; | |
223 | dataset->resp.s_aliases_cnt = s_aliases_cnt; | |
224 | ||
225 | cp = dataset->strdata; | |
226 | ||
227 | cp = mempcpy (cp, serv->s_name, s_name_len); | |
228 | cp = mempcpy (cp, serv->s_proto, s_proto_len); | |
229 | cp = mempcpy (cp, s_aliases_len, s_aliases_cnt * sizeof (uint32_t)); | |
230 | ||
231 | /* Then the aliases. */ | |
232 | aliases = cp; | |
233 | for (cnt = 0; cnt < s_aliases_cnt; ++cnt) | |
234 | cp = mempcpy (cp, serv->s_aliases[cnt], s_aliases_len[cnt]); | |
235 | ||
236 | assert (cp | |
237 | == dataset->strdata + total - offsetof (struct dataset, | |
238 | strdata)); | |
239 | ||
240 | char *key_copy = memcpy (cp, key, req->key_len); | |
241 | ||
242 | /* Now we can determine whether on refill we have to create a new | |
243 | record or not. */ | |
244 | if (he != NULL) | |
245 | { | |
246 | assert (fd == -1); | |
247 | ||
248 | if (total + req->key_len == dh->allocsize | |
249 | && total - offsetof (struct dataset, resp) == dh->recsize | |
250 | && memcmp (&dataset->resp, dh->data, | |
251 | dh->allocsize - offsetof (struct dataset, resp)) == 0) | |
252 | { | |
253 | /* The data has not changed. We will just bump the | |
254 | timeout value. Note that the new record has been | |
255 | allocated on the stack and need not be freed. */ | |
256 | dh->timeout = dataset->head.timeout; | |
257 | ++dh->nreloads; | |
258 | } | |
259 | else | |
260 | { | |
261 | /* We have to create a new record. Just allocate | |
262 | appropriate memory and copy it. */ | |
263 | struct dataset *newp | |
c52137d3 | 264 | = (struct dataset *) mempool_alloc (db, total + req->key_len, |
20e498bd | 265 | 1); |
b21fa963 UD |
266 | if (newp != NULL) |
267 | { | |
268 | /* Adjust pointers into the memory block. */ | |
269 | aliases = (char *) newp + (aliases - (char *) dataset); | |
c8703f88 UD |
270 | assert (key_copy != NULL); |
271 | key_copy = (char *) newp + (key_copy - (char *) dataset); | |
b21fa963 UD |
272 | |
273 | dataset = memcpy (newp, dataset, total + req->key_len); | |
274 | alloca_used = false; | |
275 | } | |
276 | ||
277 | /* Mark the old record as obsolete. */ | |
278 | dh->usable = false; | |
279 | } | |
280 | } | |
281 | else | |
282 | { | |
283 | /* We write the dataset before inserting it to the database | |
284 | since while inserting this thread might block and so would | |
285 | unnecessarily keep the receiver waiting. */ | |
286 | assert (fd != -1); | |
287 | ||
288 | #ifdef HAVE_SENDFILE | |
289 | if (__builtin_expect (db->mmap_used, 1) && !alloca_used) | |
290 | { | |
291 | assert (db->wr_fd != -1); | |
292 | assert ((char *) &dataset->resp > (char *) db->data); | |
306dfba9 | 293 | assert ((char *) dataset - (char *) db->head |
b21fa963 UD |
294 | + total |
295 | <= (sizeof (struct database_pers_head) | |
296 | + db->head->module * sizeof (ref_t) | |
297 | + db->head->data_size)); | |
306dfba9 AS |
298 | ssize_t written = sendfileall (fd, db->wr_fd, |
299 | (char *) &dataset->resp | |
300 | - (char *) db->head, | |
301 | dataset->head.recsize); | |
302 | if (written != dataset->head.recsize) | |
303 | { | |
b21fa963 | 304 | # ifndef __ASSUME_SENDFILE |
306dfba9 AS |
305 | if (written == -1 && errno == ENOSYS) |
306 | goto use_write; | |
b21fa963 | 307 | # endif |
306dfba9 AS |
308 | all_written = false; |
309 | } | |
b21fa963 UD |
310 | } |
311 | else | |
312 | # ifndef __ASSUME_SENDFILE | |
313 | use_write: | |
314 | # endif | |
315 | #endif | |
306dfba9 AS |
316 | if (writeall (fd, &dataset->resp, dataset->head.recsize) |
317 | != dataset->head.recsize) | |
318 | all_written = false; | |
b21fa963 UD |
319 | } |
320 | ||
321 | /* Add the record to the database. But only if it has not been | |
322 | stored on the stack. */ | |
323 | if (! alloca_used) | |
324 | { | |
325 | /* If necessary, we also propagate the data to disk. */ | |
326 | if (db->persistent) | |
327 | { | |
328 | // XXX async OK? | |
329 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; | |
330 | msync ((void *) pval, | |
331 | ((uintptr_t) dataset & pagesize_m1) | |
332 | + total + req->key_len, MS_ASYNC); | |
333 | } | |
334 | ||
7e71e55f | 335 | (void) cache_add (req->type, key_copy, req->key_len, |
528741cb | 336 | &dataset->head, true, db, owner, he == NULL); |
00ebd7ed UD |
337 | |
338 | pthread_rwlock_unlock (&db->lock); | |
b21fa963 UD |
339 | } |
340 | } | |
341 | ||
306dfba9 | 342 | if (__builtin_expect (!all_written, 0) && debug_level > 0) |
b21fa963 UD |
343 | { |
344 | char buf[256]; | |
345 | dbg_log (_("short write in %s: %s"), __FUNCTION__, | |
346 | strerror_r (errno, buf, sizeof (buf))); | |
347 | } | |
a4c7ea7b UD |
348 | |
349 | return timeout; | |
b21fa963 UD |
350 | } |
351 | ||
352 | ||
353 | static int | |
354 | lookup (int type, char *key, struct servent *resultbufp, char *buffer, | |
355 | size_t buflen, struct servent **serv) | |
356 | { | |
357 | char *proto = strrchr (key, '/'); | |
358 | if (proto != NULL && proto != key) | |
359 | { | |
360 | key = strndupa (key, proto - key); | |
361 | if (proto[1] == '\0') | |
362 | proto = NULL; | |
363 | else | |
364 | ++proto; | |
365 | } | |
366 | ||
367 | if (type == GETSERVBYNAME) | |
368 | return __getservbyname_r (key, proto, resultbufp, buffer, buflen, serv); | |
369 | ||
370 | assert (type == GETSERVBYPORT); | |
371 | return __getservbyport_r (atol (key), proto, resultbufp, buffer, buflen, | |
372 | serv); | |
373 | } | |
374 | ||
375 | ||
a4c7ea7b | 376 | static time_t |
b21fa963 UD |
377 | addservbyX (struct database_dyn *db, int fd, request_header *req, |
378 | char *key, uid_t uid, struct hashentry *he, struct datahead *dh) | |
379 | { | |
380 | /* Search for the entry matching the key. Please note that we don't | |
381 | look again in the table whether the dataset is now available. We | |
382 | simply insert it. It does not matter if it is in there twice. The | |
383 | pruning function only will look at the timestamp. */ | |
384 | size_t buflen = 1024; | |
385 | char *buffer = (char *) alloca (buflen); | |
386 | struct servent resultbuf; | |
387 | struct servent *serv; | |
388 | bool use_malloc = false; | |
389 | int errval = 0; | |
390 | ||
391 | if (__builtin_expect (debug_level > 0, 0)) | |
392 | { | |
393 | if (he == NULL) | |
394 | dbg_log (_("Haven't found \"%s\" in services cache!"), key); | |
395 | else | |
396 | dbg_log (_("Reloading \"%s\" in services cache!"), key); | |
397 | } | |
398 | ||
399 | while (lookup (req->type, key, &resultbuf, buffer, buflen, &serv) != 0 | |
400 | && (errval = errno) == ERANGE) | |
401 | { | |
402 | errno = 0; | |
403 | ||
404 | if (__builtin_expect (buflen > 32768, 0)) | |
405 | { | |
406 | char *old_buffer = buffer; | |
407 | buflen *= 2; | |
408 | buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen); | |
409 | if (buffer == NULL) | |
410 | { | |
411 | /* We ran out of memory. We cannot do anything but | |
412 | sending a negative response. In reality this should | |
413 | never happen. */ | |
414 | serv = NULL; | |
415 | buffer = old_buffer; | |
416 | ||
417 | /* We set the error to indicate this is (possibly) a | |
418 | temporary error and that it does not mean the entry | |
419 | is not available at all. */ | |
420 | errval = EAGAIN; | |
421 | break; | |
422 | } | |
423 | use_malloc = true; | |
424 | } | |
425 | else | |
426 | /* Allocate a new buffer on the stack. If possible combine it | |
427 | with the previously allocated buffer. */ | |
428 | buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen); | |
429 | } | |
430 | ||
a4c7ea7b | 431 | time_t timeout = cache_addserv (db, fd, req, key, serv, uid, he, dh, errval); |
b21fa963 UD |
432 | |
433 | if (use_malloc) | |
434 | free (buffer); | |
a4c7ea7b UD |
435 | |
436 | return timeout; | |
b21fa963 UD |
437 | } |
438 | ||
439 | ||
440 | void | |
441 | addservbyname (struct database_dyn *db, int fd, request_header *req, | |
442 | void *key, uid_t uid) | |
443 | { | |
444 | addservbyX (db, fd, req, key, uid, NULL, NULL); | |
445 | } | |
446 | ||
447 | ||
a4c7ea7b | 448 | time_t |
b21fa963 UD |
449 | readdservbyname (struct database_dyn *db, struct hashentry *he, |
450 | struct datahead *dh) | |
451 | { | |
452 | request_header req = | |
453 | { | |
454 | .type = GETSERVBYNAME, | |
455 | .key_len = he->len | |
456 | }; | |
457 | ||
a4c7ea7b | 458 | return addservbyX (db, -1, &req, db->data + he->key, he->owner, he, dh); |
b21fa963 UD |
459 | } |
460 | ||
461 | ||
462 | void | |
463 | addservbyport (struct database_dyn *db, int fd, request_header *req, | |
464 | void *key, uid_t uid) | |
465 | { | |
466 | addservbyX (db, fd, req, key, uid, NULL, NULL); | |
467 | } | |
468 | ||
469 | ||
a4c7ea7b | 470 | time_t |
b21fa963 UD |
471 | readdservbyport (struct database_dyn *db, struct hashentry *he, |
472 | struct datahead *dh) | |
473 | { | |
474 | request_header req = | |
475 | { | |
476 | .type = GETSERVBYPORT, | |
477 | .key_len = he->len | |
478 | }; | |
479 | ||
a4c7ea7b | 480 | return addservbyX (db, -1, &req, db->data + he->key, he->owner, he, dh); |
b21fa963 | 481 | } |