| /* Cache handling for services lookup. |
| Copyright (C) 2007-2016 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Ulrich Drepper <drepper@drepper.com>, 2007. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published |
| by the Free Software Foundation; version 2 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, see <http://www.gnu.org/licenses/>. */ |
| |
| #include <alloca.h> |
| #include <assert.h> |
| #include <errno.h> |
| #include <libintl.h> |
| #include <netdb.h> |
| #include <unistd.h> |
| #include <stdint.h> |
| #include <sys/mman.h> |
| #include <kernel-features.h> |
| |
| #include "nscd.h" |
| #include "dbg_log.h" |
| |
| |
| /* This is the standard reply in case the service is disabled. */ |
| static const serv_response_header disabled = |
| { |
| .version = NSCD_VERSION, |
| .found = -1, |
| .s_name_len = 0, |
| .s_proto_len = 0, |
| .s_aliases_cnt = 0, |
| .s_port = -1 |
| }; |
| |
| /* This is the struct describing how to write this record. */ |
| const struct iovec serv_iov_disabled = |
| { |
| .iov_base = (void *) &disabled, |
| .iov_len = sizeof (disabled) |
| }; |
| |
| |
| /* This is the standard reply in case we haven't found the dataset. */ |
| static const serv_response_header notfound = |
| { |
| .version = NSCD_VERSION, |
| .found = 0, |
| .s_name_len = 0, |
| .s_proto_len = 0, |
| .s_aliases_cnt = 0, |
| .s_port = -1 |
| }; |
| |
| |
| static time_t |
| cache_addserv (struct database_dyn *db, int fd, request_header *req, |
| const void *key, struct servent *serv, uid_t owner, |
| struct hashentry *const he, struct datahead *dh, int errval) |
| { |
| bool all_written = true; |
| ssize_t total; |
| time_t t = time (NULL); |
| |
| /* We allocate all data in one memory block: the iov vector, |
| the response header and the dataset itself. */ |
| struct dataset |
| { |
| struct datahead head; |
| serv_response_header resp; |
| char strdata[0]; |
| } *dataset; |
| |
| assert (offsetof (struct dataset, resp) == offsetof (struct datahead, data)); |
| |
| time_t timeout = MAX_TIMEOUT_VALUE; |
| if (serv == NULL) |
| { |
| if (he != NULL && errval == EAGAIN) |
| { |
| /* If we have an old record available but cannot find one |
| now because the service is not available we keep the old |
| record and make sure it does not get removed. */ |
| if (reload_count != UINT_MAX) |
| /* Do not reset the value if we never not reload the record. */ |
| dh->nreloads = reload_count - 1; |
| |
| /* Reload with the same time-to-live value. */ |
| timeout = dh->timeout = t + db->postimeout; |
| |
| total = 0; |
| } |
| else |
| { |
| /* We have no data. This means we send the standard reply for this |
| case. */ |
| total = sizeof (notfound); |
| |
| if (fd != -1 |
| && TEMP_FAILURE_RETRY (send (fd, ¬found, total, |
| MSG_NOSIGNAL)) != total) |
| all_written = false; |
| |
| /* If we have a transient error or cannot permanently store |
| the result, so be it. */ |
| if (errval == EAGAIN || __builtin_expect (db->negtimeout == 0, 0)) |
| { |
| /* Mark the old entry as obsolete. */ |
| if (dh != NULL) |
| dh->usable = false; |
| } |
| else if ((dataset = mempool_alloc (db, (sizeof (struct dataset) |
| + req->key_len), 1)) != NULL) |
| { |
| timeout = datahead_init_neg (&dataset->head, |
| (sizeof (struct dataset) |
| + req->key_len), total, |
| db->negtimeout); |
| |
| /* This is the reply. */ |
| memcpy (&dataset->resp, ¬found, total); |
| |
| /* Copy the key data. */ |
| memcpy (dataset->strdata, key, req->key_len); |
| |
| /* If necessary, we also propagate the data to disk. */ |
| if (db->persistent) |
| { |
| // XXX async OK? |
| uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; |
| msync ((void *) pval, |
| ((uintptr_t) dataset & pagesize_m1) |
| + sizeof (struct dataset) + req->key_len, MS_ASYNC); |
| } |
| |
| (void) cache_add (req->type, &dataset->strdata, req->key_len, |
| &dataset->head, true, db, owner, he == NULL); |
| |
| pthread_rwlock_unlock (&db->lock); |
| |
| /* Mark the old entry as obsolete. */ |
| if (dh != NULL) |
| dh->usable = false; |
| } |
| } |
| } |
| else |
| { |
| /* Determine the I/O structure. */ |
| size_t s_name_len = strlen (serv->s_name) + 1; |
| size_t s_proto_len = strlen (serv->s_proto) + 1; |
| uint32_t *s_aliases_len; |
| size_t s_aliases_cnt; |
| char *aliases; |
| char *cp; |
| size_t cnt; |
| |
| /* Determine the number of aliases. */ |
| s_aliases_cnt = 0; |
| for (cnt = 0; serv->s_aliases[cnt] != NULL; ++cnt) |
| ++s_aliases_cnt; |
| /* Determine the length of all aliases. */ |
| s_aliases_len = (uint32_t *) alloca (s_aliases_cnt * sizeof (uint32_t)); |
| total = 0; |
| for (cnt = 0; cnt < s_aliases_cnt; ++cnt) |
| { |
| s_aliases_len[cnt] = strlen (serv->s_aliases[cnt]) + 1; |
| total += s_aliases_len[cnt]; |
| } |
| |
| total += (offsetof (struct dataset, strdata) |
| + s_name_len |
| + s_proto_len |
| + s_aliases_cnt * sizeof (uint32_t)); |
| |
| /* If we refill the cache, first assume the reconrd did not |
| change. Allocate memory on the cache since it is likely |
| discarded anyway. If it turns out to be necessary to have a |
| new record we can still allocate real memory. */ |
| bool alloca_used = false; |
| dataset = NULL; |
| |
| if (he == NULL) |
| dataset = (struct dataset *) mempool_alloc (db, total + req->key_len, |
| 1); |
| |
| if (dataset == NULL) |
| { |
| /* We cannot permanently add the result in the moment. But |
| we can provide the result as is. Store the data in some |
| temporary memory. */ |
| dataset = (struct dataset *) alloca (total + req->key_len); |
| |
| /* We cannot add this record to the permanent database. */ |
| alloca_used = true; |
| } |
| |
| timeout = datahead_init_pos (&dataset->head, total + req->key_len, |
| total - offsetof (struct dataset, resp), |
| he == NULL ? 0 : dh->nreloads + 1, |
| db->postimeout); |
| |
| dataset->resp.version = NSCD_VERSION; |
| dataset->resp.found = 1; |
| dataset->resp.s_name_len = s_name_len; |
| dataset->resp.s_proto_len = s_proto_len; |
| dataset->resp.s_port = serv->s_port; |
| dataset->resp.s_aliases_cnt = s_aliases_cnt; |
| |
| cp = dataset->strdata; |
| |
| cp = mempcpy (cp, serv->s_name, s_name_len); |
| cp = mempcpy (cp, serv->s_proto, s_proto_len); |
| cp = mempcpy (cp, s_aliases_len, s_aliases_cnt * sizeof (uint32_t)); |
| |
| /* Then the aliases. */ |
| aliases = cp; |
| for (cnt = 0; cnt < s_aliases_cnt; ++cnt) |
| cp = mempcpy (cp, serv->s_aliases[cnt], s_aliases_len[cnt]); |
| |
| assert (cp |
| == dataset->strdata + total - offsetof (struct dataset, |
| strdata)); |
| |
| char *key_copy = memcpy (cp, key, req->key_len); |
| |
| /* Now we can determine whether on refill we have to create a new |
| record or not. */ |
| if (he != NULL) |
| { |
| assert (fd == -1); |
| |
| if (total + req->key_len == dh->allocsize |
| && total - offsetof (struct dataset, resp) == dh->recsize |
| && memcmp (&dataset->resp, dh->data, |
| dh->allocsize - offsetof (struct dataset, resp)) == 0) |
| { |
| /* The data has not changed. We will just bump the |
| timeout value. Note that the new record has been |
| allocated on the stack and need not be freed. */ |
| dh->timeout = dataset->head.timeout; |
| ++dh->nreloads; |
| } |
| else |
| { |
| /* We have to create a new record. Just allocate |
| appropriate memory and copy it. */ |
| struct dataset *newp |
| = (struct dataset *) mempool_alloc (db, total + req->key_len, |
| 1); |
| if (newp != NULL) |
| { |
| /* Adjust pointers into the memory block. */ |
| aliases = (char *) newp + (aliases - (char *) dataset); |
| assert (key_copy != NULL); |
| key_copy = (char *) newp + (key_copy - (char *) dataset); |
| |
| dataset = memcpy (newp, dataset, total + req->key_len); |
| alloca_used = false; |
| } |
| |
| /* Mark the old record as obsolete. */ |
| dh->usable = false; |
| } |
| } |
| else |
| { |
| /* We write the dataset before inserting it to the database |
| since while inserting this thread might block and so would |
| unnecessarily keep the receiver waiting. */ |
| assert (fd != -1); |
| |
| #ifdef HAVE_SENDFILE |
| if (__builtin_expect (db->mmap_used, 1) && !alloca_used) |
| { |
| assert (db->wr_fd != -1); |
| assert ((char *) &dataset->resp > (char *) db->data); |
| assert ((char *) dataset - (char *) db->head |
| + total |
| <= (sizeof (struct database_pers_head) |
| + db->head->module * sizeof (ref_t) |
| + db->head->data_size)); |
| ssize_t written = sendfileall (fd, db->wr_fd, |
| (char *) &dataset->resp |
| - (char *) db->head, |
| dataset->head.recsize); |
| if (written != dataset->head.recsize) |
| { |
| # ifndef __ASSUME_SENDFILE |
| if (written == -1 && errno == ENOSYS) |
| goto use_write; |
| # endif |
| all_written = false; |
| } |
| } |
| else |
| # ifndef __ASSUME_SENDFILE |
| use_write: |
| # endif |
| #endif |
| if (writeall (fd, &dataset->resp, dataset->head.recsize) |
| != dataset->head.recsize) |
| all_written = false; |
| } |
| |
| /* Add the record to the database. But only if it has not been |
| stored on the stack. */ |
| if (! alloca_used) |
| { |
| /* If necessary, we also propagate the data to disk. */ |
| if (db->persistent) |
| { |
| // XXX async OK? |
| uintptr_t pval = (uintptr_t) dataset & ~pagesize_m1; |
| msync ((void *) pval, |
| ((uintptr_t) dataset & pagesize_m1) |
| + total + req->key_len, MS_ASYNC); |
| } |
| |
| (void) cache_add (req->type, key_copy, req->key_len, |
| &dataset->head, true, db, owner, he == NULL); |
| |
| pthread_rwlock_unlock (&db->lock); |
| } |
| } |
| |
| if (__builtin_expect (!all_written, 0) && debug_level > 0) |
| { |
| char buf[256]; |
| dbg_log (_("short write in %s: %s"), __FUNCTION__, |
| strerror_r (errno, buf, sizeof (buf))); |
| } |
| |
| return timeout; |
| } |
| |
| |
| static int |
| lookup (int type, char *key, struct servent *resultbufp, char *buffer, |
| size_t buflen, struct servent **serv) |
| { |
| char *proto = strrchr (key, '/'); |
| if (proto != NULL && proto != key) |
| { |
| key = strndupa (key, proto - key); |
| if (proto[1] == '\0') |
| proto = NULL; |
| else |
| ++proto; |
| } |
| |
| if (type == GETSERVBYNAME) |
| return __getservbyname_r (key, proto, resultbufp, buffer, buflen, serv); |
| |
| assert (type == GETSERVBYPORT); |
| return __getservbyport_r (atol (key), proto, resultbufp, buffer, buflen, |
| serv); |
| } |
| |
| |
| static time_t |
| addservbyX (struct database_dyn *db, int fd, request_header *req, |
| char *key, uid_t uid, struct hashentry *he, struct datahead *dh) |
| { |
| /* Search for the entry matching the key. Please note that we don't |
| look again in the table whether the dataset is now available. We |
| simply insert it. It does not matter if it is in there twice. The |
| pruning function only will look at the timestamp. */ |
| size_t buflen = 1024; |
| char *buffer = (char *) alloca (buflen); |
| struct servent resultbuf; |
| struct servent *serv; |
| bool use_malloc = false; |
| int errval = 0; |
| |
| if (__glibc_unlikely (debug_level > 0)) |
| { |
| if (he == NULL) |
| dbg_log (_("Haven't found \"%s\" in services cache!"), key); |
| else |
| dbg_log (_("Reloading \"%s\" in services cache!"), key); |
| } |
| |
| while (lookup (req->type, key, &resultbuf, buffer, buflen, &serv) != 0 |
| && (errval = errno) == ERANGE) |
| { |
| errno = 0; |
| |
| if (__glibc_unlikely (buflen > 32768)) |
| { |
| char *old_buffer = buffer; |
| buflen *= 2; |
| buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen); |
| if (buffer == NULL) |
| { |
| /* We ran out of memory. We cannot do anything but |
| sending a negative response. In reality this should |
| never happen. */ |
| serv = NULL; |
| buffer = old_buffer; |
| |
| /* We set the error to indicate this is (possibly) a |
| temporary error and that it does not mean the entry |
| is not available at all. */ |
| errval = EAGAIN; |
| break; |
| } |
| use_malloc = true; |
| } |
| else |
| /* Allocate a new buffer on the stack. If possible combine it |
| with the previously allocated buffer. */ |
| buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen); |
| } |
| |
| time_t timeout = cache_addserv (db, fd, req, key, serv, uid, he, dh, errval); |
| |
| if (use_malloc) |
| free (buffer); |
| |
| return timeout; |
| } |
| |
| |
| void |
| addservbyname (struct database_dyn *db, int fd, request_header *req, |
| void *key, uid_t uid) |
| { |
| addservbyX (db, fd, req, key, uid, NULL, NULL); |
| } |
| |
| |
| time_t |
| readdservbyname (struct database_dyn *db, struct hashentry *he, |
| struct datahead *dh) |
| { |
| request_header req = |
| { |
| .type = GETSERVBYNAME, |
| .key_len = he->len |
| }; |
| |
| return addservbyX (db, -1, &req, db->data + he->key, he->owner, he, dh); |
| } |
| |
| |
| void |
| addservbyport (struct database_dyn *db, int fd, request_header *req, |
| void *key, uid_t uid) |
| { |
| addservbyX (db, fd, req, key, uid, NULL, NULL); |
| } |
| |
| |
| time_t |
| readdservbyport (struct database_dyn *db, struct hashentry *he, |
| struct datahead *dh) |
| { |
| request_header req = |
| { |
| .type = GETSERVBYPORT, |
| .key_len = he->len |
| }; |
| |
| return addservbyX (db, -1, &req, db->data + he->key, he->owner, he, dh); |
| } |