diff options
Diffstat (limited to 'nscd/servicescache.c')
| -rw-r--r-- | nscd/servicescache.c | 473 |
1 files changed, 473 insertions, 0 deletions
diff --git a/nscd/servicescache.c b/nscd/servicescache.c new file mode 100644 index 0000000000..ea4fa35100 --- /dev/null +++ b/nscd/servicescache.c @@ -0,0 +1,473 @@ +/* Cache handling for services lookup. + Copyright (C) 2007 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 version 2 as + published by the Free Software Foundation. + + 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, write to the Free Software Foundation, + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +#include <alloca.h> +#include <assert.h> +#include <errno.h> +#include <libintl.h> +#include <netdb.h> +#include <unistd.h> +#include <sys/mman.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 void +cache_addserv (struct database_dyn *db, int fd, request_header *req, + const void *key, struct servent *serv, uid_t owner, + struct hashentry *he, struct datahead *dh, int errval) +{ + ssize_t total; + ssize_t written; + 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)); + + 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; + + written = total = 0; + } + else + { + /* We have no data. This means we send the standard reply for this + case. */ + total = sizeof (notfound); + + written = TEMP_FAILURE_RETRY (send (fd, ¬found, total, + MSG_NOSIGNAL)); + + dataset = mempool_alloc (db, sizeof (struct dataset) + req->key_len); + /* If we cannot permanently store the result, so be it. */ + if (dataset != NULL) + { + dataset->head.allocsize = sizeof (struct dataset) + req->key_len; + dataset->head.recsize = total; + dataset->head.notfound = true; + dataset->head.nreloads = 0; + dataset->head.usable = true; + + /* Compute the timeout time. */ + dataset->head.timeout = t + 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); + } + + /* Now get the lock to safely insert the records. */ + pthread_rwlock_rdlock (&db->lock); + + if (cache_add (req->type, &dataset->strdata, req->key_len, + &dataset->head, true, db, owner) < 0) + /* Ensure the data can be recovered. */ + dataset->head.usable = false; + + pthread_rwlock_unlock (&db->lock); + + /* Mark the old entry as obsolete. */ + if (dh != NULL) + dh->usable = false; + } + else + ++db->head->addfailed; + } + } + 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 += (sizeof (struct dataset) + + s_name_len + + s_proto_len + + s_aliases_cnt * sizeof (uint32_t)); + written = total; + + /* 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); + if (dataset == NULL) + ++db->head->addfailed; + } + + 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; + } + + dataset->head.allocsize = total + req->key_len; + dataset->head.recsize = total - offsetof (struct dataset, resp); + dataset->head.notfound = false; + dataset->head.nreloads = he == NULL ? 0 : (dh->nreloads + 1); + dataset->head.usable = true; + + /* Compute the timeout time. */ + dataset->head.timeout = t + 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); + if (newp != NULL) + { + /* Adjust pointers into the memory block. */ + aliases = (char *) newp + (aliases - (char *) dataset); + if (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->resp - (char *) db->head + + total + <= (sizeof (struct database_pers_head) + + db->head->module * sizeof (ref_t) + + db->head->data_size)); + written = sendfileall (fd, db->wr_fd, + (char *) &dataset->resp + - (char *) db->head, total); +# ifndef __ASSUME_SENDFILE + if (written == -1 && errno == ENOSYS) + goto use_write; +# endif + } + else +# ifndef __ASSUME_SENDFILE + use_write: +# endif +#endif + written = writeall (fd, &dataset->resp, total); + } + + /* 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); + } + + /* Now get the lock to safely insert the records. */ + pthread_rwlock_rdlock (&db->lock); + + if (cache_add (req->type, key_copy, req->key_len, + &dataset->head, true, db, owner) < 0) + /* Could not allocate memory. Make sure the + data gets discarded. */ + dataset->head.usable = false; + + pthread_rwlock_unlock (&db->lock); + } + } + + if (__builtin_expect (written != total, 0) && debug_level > 0) + { + char buf[256]; + dbg_log (_("short write in %s: %s"), __FUNCTION__, + strerror_r (errno, buf, sizeof (buf))); + } +} + + +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 void +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 (__builtin_expect (debug_level > 0, 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 (__builtin_expect (buflen > 32768, 0)) + { + 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); + } + + cache_addserv (db, fd, req, key, serv, uid, he, dh, errval); + + if (use_malloc) + free (buffer); +} + + +void +addservbyname (struct database_dyn *db, int fd, request_header *req, + void *key, uid_t uid) +{ + addservbyX (db, fd, req, key, uid, NULL, NULL); +} + + +void +readdservbyname (struct database_dyn *db, struct hashentry *he, + struct datahead *dh) +{ + request_header req = + { + .type = GETSERVBYNAME, + .key_len = he->len + }; + + 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); +} + + +void +readdservbyport (struct database_dyn *db, struct hashentry *he, + struct datahead *dh) +{ + request_header req = + { + .type = GETSERVBYPORT, + .key_len = he->len + }; + + addservbyX (db, -1, &req, db->data + he->key, he->owner, he, dh); +} |