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1 | /* Cache handling for services lookup. | |
2 | Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc. | |
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 | |
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. | |
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 | |
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. */ | |
19 | ||
20 | #include <alloca.h> | |
21 | #include <assert.h> | |
22 | #include <errno.h> | |
23 | #include <libintl.h> | |
24 | #include <netdb.h> | |
25 | #include <unistd.h> | |
26 | #include <sys/mman.h> | |
27 | #include <kernel-features.h> | |
28 | ||
29 | #include "nscd.h" | |
30 | #include "dbg_log.h" | |
31 | ||
32 | ||
33 | /* This is the standard reply in case the service is disabled. */ | |
34 | static const serv_response_header disabled = | |
35 | { | |
36 | .version = NSCD_VERSION, | |
37 | .found = -1, | |
38 | .s_name_len = 0, | |
39 | .s_proto_len = 0, | |
40 | .s_aliases_cnt = 0, | |
41 | .s_port = -1 | |
42 | }; | |
43 | ||
44 | /* This is the struct describing how to write this record. */ | |
45 | const struct iovec serv_iov_disabled = | |
46 | { | |
47 | .iov_base = (void *) &disabled, | |
48 | .iov_len = sizeof (disabled) | |
49 | }; | |
50 | ||
51 | ||
52 | /* This is the standard reply in case we haven't found the dataset. */ | |
53 | static const serv_response_header notfound = | |
54 | { | |
55 | .version = NSCD_VERSION, | |
56 | .found = 0, | |
57 | .s_name_len = 0, | |
58 | .s_proto_len = 0, | |
59 | .s_aliases_cnt = 0, | |
60 | .s_port = -1 | |
61 | }; | |
62 | ||
63 | ||
64 | static void | |
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) | |
68 | { | |
69 | ssize_t total; | |
70 | ssize_t written; | |
71 | time_t t = time (NULL); | |
72 | ||
73 | /* We allocate all data in one memory block: the iov vector, | |
74 | the response header and the dataset itself. */ | |
75 | struct dataset | |
76 | { | |
77 | struct datahead head; | |
78 | serv_response_header resp; | |
79 | char strdata[0]; | |
80 | } *dataset; | |
81 | ||
82 | assert (offsetof (struct dataset, resp) == offsetof (struct datahead, data)); | |
83 | ||
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 | ||
95 | written = total = 0; | |
96 | } | |
97 | else | |
98 | { | |
99 | /* We have no data. This means we send the standard reply for this | |
100 | case. */ | |
101 | total = sizeof (notfound); | |
102 | ||
103 | written = TEMP_FAILURE_RETRY (send (fd, ¬found, total, | |
104 | MSG_NOSIGNAL)); | |
105 | ||
106 | dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len, | |
107 | 1); | |
108 | /* If we cannot permanently store the result, so be it. */ | |
109 | if (dataset != NULL) | |
110 | { | |
111 | dataset->head.allocsize = sizeof (struct dataset) + req->key_len; | |
112 | dataset->head.recsize = total; | |
113 | dataset->head.notfound = true; | |
114 | dataset->head.nreloads = 0; | |
115 | dataset->head.usable = true; | |
116 | ||
117 | /* Compute the timeout time. */ | |
118 | dataset->head.timeout = t + db->negtimeout; | |
119 | ||
120 | /* This is the reply. */ | |
121 | memcpy (&dataset->resp, ¬found, total); | |
122 | ||
123 | /* Copy the key data. */ | |
124 | memcpy (dataset->strdata, key, req->key_len); | |
125 | ||
126 | /* If necessary, we also propagate the data to disk. */ | |
127 | if (db->persistent) | |
128 | { | |
129 | // XXX async OK? | |
130 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; | |
131 | msync ((void *) pval, | |
132 | ((uintptr_t) dataset & pagesize_m1) | |
133 | + sizeof (struct dataset) + req->key_len, MS_ASYNC); | |
134 | } | |
135 | ||
136 | (void) cache_add (req->type, &dataset->strdata, req->key_len, | |
137 | &dataset->head, true, db, owner, he == NULL); | |
138 | ||
139 | /* Mark the old entry as obsolete. */ | |
140 | if (dh != NULL) | |
141 | dh->usable = false; | |
142 | } | |
143 | } | |
144 | } | |
145 | else | |
146 | { | |
147 | /* Determine the I/O structure. */ | |
148 | size_t s_name_len = strlen (serv->s_name) + 1; | |
149 | size_t s_proto_len = strlen (serv->s_proto) + 1; | |
150 | uint32_t *s_aliases_len; | |
151 | size_t s_aliases_cnt; | |
152 | char *aliases; | |
153 | char *cp; | |
154 | size_t cnt; | |
155 | ||
156 | /* Determine the number of aliases. */ | |
157 | s_aliases_cnt = 0; | |
158 | for (cnt = 0; serv->s_aliases[cnt] != NULL; ++cnt) | |
159 | ++s_aliases_cnt; | |
160 | /* Determine the length of all aliases. */ | |
161 | s_aliases_len = (uint32_t *) alloca (s_aliases_cnt * sizeof (uint32_t)); | |
162 | total = 0; | |
163 | for (cnt = 0; cnt < s_aliases_cnt; ++cnt) | |
164 | { | |
165 | s_aliases_len[cnt] = strlen (serv->s_aliases[cnt]) + 1; | |
166 | total += s_aliases_len[cnt]; | |
167 | } | |
168 | ||
169 | total += (offsetof (struct dataset, strdata) | |
170 | + s_name_len | |
171 | + s_proto_len | |
172 | + s_aliases_cnt * sizeof (uint32_t)); | |
173 | written = total; | |
174 | ||
175 | /* If we refill the cache, first assume the reconrd did not | |
176 | change. Allocate memory on the cache since it is likely | |
177 | discarded anyway. If it turns out to be necessary to have a | |
178 | new record we can still allocate real memory. */ | |
179 | bool alloca_used = false; | |
180 | dataset = NULL; | |
181 | ||
182 | if (he == NULL) | |
183 | dataset = (struct dataset *) mempool_alloc (db, total + req->key_len, | |
184 | 1); | |
185 | ||
186 | if (dataset == NULL) | |
187 | { | |
188 | /* We cannot permanently add the result in the moment. But | |
189 | we can provide the result as is. Store the data in some | |
190 | temporary memory. */ | |
191 | dataset = (struct dataset *) alloca (total + req->key_len); | |
192 | ||
193 | /* We cannot add this record to the permanent database. */ | |
194 | alloca_used = true; | |
195 | } | |
196 | ||
197 | dataset->head.allocsize = total + req->key_len; | |
198 | dataset->head.recsize = total - offsetof (struct dataset, resp); | |
199 | dataset->head.notfound = false; | |
200 | dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1); | |
201 | dataset->head.usable = true; | |
202 | ||
203 | /* Compute the timeout time. */ | |
204 | dataset->head.timeout = t + db->postimeout; | |
205 | ||
206 | dataset->resp.version = NSCD_VERSION; | |
207 | dataset->resp.found = 1; | |
208 | dataset->resp.s_name_len = s_name_len; | |
209 | dataset->resp.s_proto_len = s_proto_len; | |
210 | dataset->resp.s_port = serv->s_port; | |
211 | dataset->resp.s_aliases_cnt = s_aliases_cnt; | |
212 | ||
213 | cp = dataset->strdata; | |
214 | ||
215 | cp = mempcpy (cp, serv->s_name, s_name_len); | |
216 | cp = mempcpy (cp, serv->s_proto, s_proto_len); | |
217 | cp = mempcpy (cp, s_aliases_len, s_aliases_cnt * sizeof (uint32_t)); | |
218 | ||
219 | /* Then the aliases. */ | |
220 | aliases = cp; | |
221 | for (cnt = 0; cnt < s_aliases_cnt; ++cnt) | |
222 | cp = mempcpy (cp, serv->s_aliases[cnt], s_aliases_len[cnt]); | |
223 | ||
224 | assert (cp | |
225 | == dataset->strdata + total - offsetof (struct dataset, | |
226 | strdata)); | |
227 | ||
228 | char *key_copy = memcpy (cp, key, req->key_len); | |
229 | ||
230 | /* Now we can determine whether on refill we have to create a new | |
231 | record or not. */ | |
232 | if (he != NULL) | |
233 | { | |
234 | assert (fd == -1); | |
235 | ||
236 | if (total + req->key_len == dh->allocsize | |
237 | && total - offsetof (struct dataset, resp) == dh->recsize | |
238 | && memcmp (&dataset->resp, dh->data, | |
239 | dh->allocsize - offsetof (struct dataset, resp)) == 0) | |
240 | { | |
241 | /* The data has not changed. We will just bump the | |
242 | timeout value. Note that the new record has been | |
243 | allocated on the stack and need not be freed. */ | |
244 | dh->timeout = dataset->head.timeout; | |
245 | ++dh->nreloads; | |
246 | } | |
247 | else | |
248 | { | |
249 | /* We have to create a new record. Just allocate | |
250 | appropriate memory and copy it. */ | |
251 | struct dataset *newp | |
252 | = (struct dataset *) mempool_alloc (db, total + req->key_len, | |
253 | 1); | |
254 | if (newp != NULL) | |
255 | { | |
256 | /* Adjust pointers into the memory block. */ | |
257 | aliases = (char *) newp + (aliases - (char *) dataset); | |
258 | assert (key_copy != NULL); | |
259 | key_copy = (char *) newp + (key_copy - (char *) dataset); | |
260 | ||
261 | dataset = memcpy (newp, dataset, total + req->key_len); | |
262 | alloca_used = false; | |
263 | } | |
264 | ||
265 | /* Mark the old record as obsolete. */ | |
266 | dh->usable = false; | |
267 | } | |
268 | } | |
269 | else | |
270 | { | |
271 | /* We write the dataset before inserting it to the database | |
272 | since while inserting this thread might block and so would | |
273 | unnecessarily keep the receiver waiting. */ | |
274 | assert (fd != -1); | |
275 | ||
276 | #ifdef HAVE_SENDFILE | |
277 | if (__builtin_expect (db->mmap_used, 1) && !alloca_used) | |
278 | { | |
279 | assert (db->wr_fd != -1); | |
280 | assert ((char *) &dataset->resp > (char *) db->data); | |
281 | assert ((char *) &dataset->resp - (char *) db->head | |
282 | + total | |
283 | <= (sizeof (struct database_pers_head) | |
284 | + db->head->module * sizeof (ref_t) | |
285 | + db->head->data_size)); | |
286 | written = sendfileall (fd, db->wr_fd, | |
287 | (char *) &dataset->resp | |
288 | - (char *) db->head, total); | |
289 | # ifndef __ASSUME_SENDFILE | |
290 | if (written == -1 && errno == ENOSYS) | |
291 | goto use_write; | |
292 | # endif | |
293 | } | |
294 | else | |
295 | # ifndef __ASSUME_SENDFILE | |
296 | use_write: | |
297 | # endif | |
298 | #endif | |
299 | written = writeall (fd, &dataset->resp, total); | |
300 | } | |
301 | ||
302 | /* Add the record to the database. But only if it has not been | |
303 | stored on the stack. */ | |
304 | if (! alloca_used) | |
305 | { | |
306 | /* If necessary, we also propagate the data to disk. */ | |
307 | if (db->persistent) | |
308 | { | |
309 | // XXX async OK? | |
310 | uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; | |
311 | msync ((void *) pval, | |
312 | ((uintptr_t) dataset & pagesize_m1) | |
313 | + total + req->key_len, MS_ASYNC); | |
314 | } | |
315 | ||
316 | (void) cache_add (req->type, key_copy, req->key_len, | |
317 | &dataset->head, true, db, owner, he == NULL); | |
318 | } | |
319 | } | |
320 | ||
321 | if (__builtin_expect (written != total, 0) && debug_level > 0) | |
322 | { | |
323 | char buf[256]; | |
324 | dbg_log (_("short write in %s: %s"), __FUNCTION__, | |
325 | strerror_r (errno, buf, sizeof (buf))); | |
326 | } | |
327 | } | |
328 | ||
329 | ||
330 | static int | |
331 | lookup (int type, char *key, struct servent *resultbufp, char *buffer, | |
332 | size_t buflen, struct servent **serv) | |
333 | { | |
334 | char *proto = strrchr (key, '/'); | |
335 | if (proto != NULL && proto != key) | |
336 | { | |
337 | key = strndupa (key, proto - key); | |
338 | if (proto[1] == '\0') | |
339 | proto = NULL; | |
340 | else | |
341 | ++proto; | |
342 | } | |
343 | ||
344 | if (type == GETSERVBYNAME) | |
345 | return __getservbyname_r (key, proto, resultbufp, buffer, buflen, serv); | |
346 | ||
347 | assert (type == GETSERVBYPORT); | |
348 | return __getservbyport_r (atol (key), proto, resultbufp, buffer, buflen, | |
349 | serv); | |
350 | } | |
351 | ||
352 | ||
353 | static void | |
354 | addservbyX (struct database_dyn *db, int fd, request_header *req, | |
355 | char *key, uid_t uid, struct hashentry *he, struct datahead *dh) | |
356 | { | |
357 | /* Search for the entry matching the key. Please note that we don't | |
358 | look again in the table whether the dataset is now available. We | |
359 | simply insert it. It does not matter if it is in there twice. The | |
360 | pruning function only will look at the timestamp. */ | |
361 | size_t buflen = 1024; | |
362 | char *buffer = (char *) alloca (buflen); | |
363 | struct servent resultbuf; | |
364 | struct servent *serv; | |
365 | bool use_malloc = false; | |
366 | int errval = 0; | |
367 | ||
368 | if (__builtin_expect (debug_level > 0, 0)) | |
369 | { | |
370 | if (he == NULL) | |
371 | dbg_log (_("Haven't found \"%s\" in services cache!"), key); | |
372 | else | |
373 | dbg_log (_("Reloading \"%s\" in services cache!"), key); | |
374 | } | |
375 | ||
376 | while (lookup (req->type, key, &resultbuf, buffer, buflen, &serv) != 0 | |
377 | && (errval = errno) == ERANGE) | |
378 | { | |
379 | errno = 0; | |
380 | ||
381 | if (__builtin_expect (buflen > 32768, 0)) | |
382 | { | |
383 | char *old_buffer = buffer; | |
384 | buflen *= 2; | |
385 | buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen); | |
386 | if (buffer == NULL) | |
387 | { | |
388 | /* We ran out of memory. We cannot do anything but | |
389 | sending a negative response. In reality this should | |
390 | never happen. */ | |
391 | serv = NULL; | |
392 | buffer = old_buffer; | |
393 | ||
394 | /* We set the error to indicate this is (possibly) a | |
395 | temporary error and that it does not mean the entry | |
396 | is not available at all. */ | |
397 | errval = EAGAIN; | |
398 | break; | |
399 | } | |
400 | use_malloc = true; | |
401 | } | |
402 | else | |
403 | /* Allocate a new buffer on the stack. If possible combine it | |
404 | with the previously allocated buffer. */ | |
405 | buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen); | |
406 | } | |
407 | ||
408 | cache_addserv (db, fd, req, key, serv, uid, he, dh, errval); | |
409 | ||
410 | if (use_malloc) | |
411 | free (buffer); | |
412 | } | |
413 | ||
414 | ||
415 | void | |
416 | addservbyname (struct database_dyn *db, int fd, request_header *req, | |
417 | void *key, uid_t uid) | |
418 | { | |
419 | addservbyX (db, fd, req, key, uid, NULL, NULL); | |
420 | } | |
421 | ||
422 | ||
423 | void | |
424 | readdservbyname (struct database_dyn *db, struct hashentry *he, | |
425 | struct datahead *dh) | |
426 | { | |
427 | request_header req = | |
428 | { | |
429 | .type = GETSERVBYNAME, | |
430 | .key_len = he->len | |
431 | }; | |
432 | ||
433 | addservbyX (db, -1, &req, db->data + he->key, he->owner, he, dh); | |
434 | } | |
435 | ||
436 | ||
437 | void | |
438 | addservbyport (struct database_dyn *db, int fd, request_header *req, | |
439 | void *key, uid_t uid) | |
440 | { | |
441 | addservbyX (db, fd, req, key, uid, NULL, NULL); | |
442 | } | |
443 | ||
444 | ||
445 | void | |
446 | readdservbyport (struct database_dyn *db, struct hashentry *he, | |
447 | struct datahead *dh) | |
448 | { | |
449 | request_header req = | |
450 | { | |
451 | .type = GETSERVBYPORT, | |
452 | .key_len = he->len | |
453 | }; | |
454 | ||
455 | addservbyX (db, -1, &req, db->data + he->key, he->owner, he, dh); | |
456 | } |