/* Cache handling for host lookup.
- Copyright (C) 1998-2005, 2006, 2007 Free Software Foundation, Inc.
+ Copyright (C) 1998-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
- Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published
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. */
+ along with this program; if not, see <https://www.gnu.org/licenses/>. */
#include <alloca.h>
#include <assert.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
+#include <stdint.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <sys/mman.h>
#include <stackinfo.h>
+#include <scratch_buffer.h>
#include "nscd.h"
#include "dbg_log.h"
-#ifdef HAVE_SENDFILE
-# include <kernel-features.h>
-#endif
/* This is the standard reply in case the service is disabled. */
};
-static void
+/* This is the standard reply in case there are temporary problems. */
+static const hst_response_header tryagain =
+{
+ .version = NSCD_VERSION,
+ .found = 0,
+ .h_name_len = 0,
+ .h_aliases_cnt = 0,
+ .h_addrtype = -1,
+ .h_length = -1,
+ .h_addr_list_cnt = 0,
+ .error = TRY_AGAIN
+};
+
+
+static time_t
cache_addhst (struct database_dyn *db, int fd, request_header *req,
const void *key, struct hostent *hst, uid_t owner,
- struct hashentry *he, struct datahead *dh, int errval)
+ struct hashentry *const he, struct datahead *dh, int errval,
+ int32_t ttl)
{
- ssize_t total;
- ssize_t written;
+ bool all_written = true;
time_t t = time (NULL);
/* We allocate all data in one memory block: the iov vector,
assert (offsetof (struct dataset, resp) == offsetof (struct datahead, data));
+ time_t timeout = MAX_TIMEOUT_VALUE;
if (hst == NULL)
{
if (he != NULL && errval == EAGAIN)
/* Do not reset the value if we never not reload the record. */
dh->nreloads = reload_count - 1;
- written = total = 0;
+ /* Reload with the same time-to-live value. */
+ timeout = dh->timeout = t + dh->ttl;
}
else
{
/* We have no data. This means we send the standard reply for this
- case. */
- written = total = sizeof (notfound);
+ case. Possibly this is only temporary. */
+ ssize_t total = sizeof (notfound);
+ assert (sizeof (notfound) == sizeof (tryagain));
- if (fd != -1)
- written = TEMP_FAILURE_RETRY (send (fd, ¬found, total,
- MSG_NOSIGNAL));
+ const hst_response_header *resp = (errval == EAGAIN
+ ? &tryagain : ¬found);
- 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;
+ if (fd != -1
+ && TEMP_FAILURE_RETRY (send (fd, resp, total,
+ MSG_NOSIGNAL)) != total)
+ all_written = false;
- /* Compute the timeout time. */
- dataset->head.timeout = t + db->negtimeout;
+ /* 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,
+ (ttl == INT32_MAX
+ ? db->negtimeout : ttl));
/* This is the reply. */
- memcpy (&dataset->resp, ¬found, total);
+ memcpy (&dataset->resp, resp, total);
/* Copy the key data. */
memcpy (dataset->strdata, key, req->key_len);
+ 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;
+ (void) cache_add (req->type, &dataset->strdata, req->key_len,
+ &dataset->head, true, db, owner, he == NULL);
pthread_rwlock_unlock (&db->lock);
if (dh != NULL)
dh->usable = false;
}
- else
- ++db->head->addfailed;
}
}
else
size_t h_aliases_cnt;
uint32_t *h_aliases_len;
size_t h_addr_list_cnt;
- int addr_list_type;
char *addresses;
char *aliases;
char *key_copy = NULL;
char *cp;
size_t cnt;
+ ssize_t total;
/* Determine the number of aliases. */
h_aliases_cnt = 0;
if (h_addr_list_cnt == 0)
/* Invalid entry. */
- return;
+ return MAX_TIMEOUT_VALUE;
total += (sizeof (struct dataset)
+ h_name_len
+ h_aliases_cnt * sizeof (uint32_t)
+ h_addr_list_cnt * hst->h_length);
- written = total;
/* If we refill the cache, first assume the reconrd did not
change. Allocate memory on the cache since it is likely
questionable whether it is worthwhile complicating the cache
handling just for handling such a special case. */
if (he == NULL && h_addr_list_cnt == 1)
- {
- dataset = (struct dataset *) mempool_alloc (db,
- total + req->key_len);
- if (dataset == NULL)
- ++db->head->addfailed;
- }
+ dataset = (struct dataset *) mempool_alloc (db, total + req->key_len,
+ 1);
if (dataset == NULL)
{
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;
+ timeout = datahead_init_pos (&dataset->head, total + req->key_len,
+ total - offsetof (struct dataset, resp),
+ he == NULL ? 0 : dh->nreloads + 1,
+ ttl == INT32_MAX ? db->postimeout : ttl);
dataset->resp.version = NSCD_VERSION;
dataset->resp.found = 1;
dataset->resp.h_addr_list_cnt = h_addr_list_cnt;
dataset->resp.error = NETDB_SUCCESS;
+ /* Make sure there is no gap. */
+ assert ((char *) (&dataset->resp.error + 1) == dataset->strdata);
+
cp = dataset->strdata;
cp = mempcpy (cp, hst->h_name, h_name_len);
we explicitly add the name here. */
key_copy = memcpy (cp, key, req->key_len);
+ assert ((char *) &dataset->resp + dataset->head.recsize == cp);
+
/* Now we can determine whether on refill we have to create a new
record or not. */
if (he != NULL)
/* 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. */
+ assert (h_addr_list_cnt == 1);
+ dh->ttl = dataset->head.ttl;
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)
+ if (h_addr_list_cnt == 1)
{
- /* Adjust pointers into the memory block. */
- addresses = (char *) newp + (addresses - (char *) dataset);
- 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;
+ /* 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. */
+ addresses = (char *) newp + (addresses
+ - (char *) dataset);
+ 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. */
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);
+ 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
+ total + req->key_len, MS_ASYNC);
}
- addr_list_type = (hst->h_length == NS_INADDRSZ
- ? GETHOSTBYADDR : GETHOSTBYADDRv6);
-
- /* Now get the lock to safely insert the records. */
- pthread_rwlock_rdlock (&db->lock);
-
/* NB: the following code is really complicated. It has
seemlingly duplicated code paths which do the same. The
problem is that we always must add the hash table entry
|| req->type == GETHOSTBYADDR
|| req->type == GETHOSTBYADDRv6);
- 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;
+ (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 (written != total, 0) && debug_level > 0)
+ 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, void *key, struct hostent *resultbufp, char *buffer,
- size_t buflen, struct hostent **hst)
+ size_t buflen, struct hostent **hst, int32_t *ttlp)
{
if (type == GETHOSTBYNAME)
- return __gethostbyname2_r (key, AF_INET, resultbufp, buffer, buflen, hst,
- &h_errno);
+ return __gethostbyname3_r (key, AF_INET, resultbufp, buffer, buflen, hst,
+ &h_errno, ttlp, NULL);
if (type == GETHOSTBYNAMEv6)
- return __gethostbyname2_r (key, AF_INET6, resultbufp, buffer, buflen, hst,
- &h_errno);
+ return __gethostbyname3_r (key, AF_INET6, resultbufp, buffer, buflen, hst,
+ &h_errno, ttlp, NULL);
if (type == GETHOSTBYADDR)
- return __gethostbyaddr_r (key, NS_INADDRSZ, AF_INET, resultbufp, buffer,
- buflen, hst, &h_errno);
- return __gethostbyaddr_r (key, NS_IN6ADDRSZ, AF_INET6, resultbufp, buffer,
- buflen, hst, &h_errno);
+ return __gethostbyaddr2_r (key, NS_INADDRSZ, AF_INET, resultbufp, buffer,
+ buflen, hst, &h_errno, ttlp);
+ return __gethostbyaddr2_r (key, NS_IN6ADDRSZ, AF_INET6, resultbufp, buffer,
+ buflen, hst, &h_errno, ttlp);
}
-static void
+static time_t
addhstbyX (struct database_dyn *db, int fd, request_header *req,
void *key, uid_t uid, struct hashentry *he, struct datahead *dh)
{
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. */
- int buflen = 1024;
- char *buffer = (char *) alloca (buflen);
struct hostent resultbuf;
struct hostent *hst;
- bool use_malloc = false;
int errval = 0;
+ int32_t ttl = INT32_MAX;
- if (__builtin_expect (debug_level > 0, 0))
+ if (__glibc_unlikely (debug_level > 0))
{
const char *str;
char buf[INET6_ADDRSTRLEN + 1];
dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) str);
}
- while (lookup (req->type, key, &resultbuf, buffer, buflen, &hst) != 0
+ struct scratch_buffer tmpbuf;
+ scratch_buffer_init (&tmpbuf);
+
+ while (lookup (req->type, key, &resultbuf,
+ tmpbuf.data, tmpbuf.length, &hst, &ttl) != 0
&& h_errno == NETDB_INTERNAL
&& (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. */
- hst = 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_addhst (db, fd, req, key, hst, uid, he, dh,
- h_errno == TRY_AGAIN ? errval : 0);
-
- if (use_malloc)
- free (buffer);
+ if (!scratch_buffer_grow (&tmpbuf))
+ {
+ /* We ran out of memory. We cannot do anything but sending a
+ negative response. In reality this should never
+ happen. */
+ hst = NULL;
+ /* 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. */
+ h_errno = TRY_AGAIN;
+ errval = EAGAIN;
+ break;
+ }
+
+ time_t timeout = cache_addhst (db, fd, req, key, hst, uid, he, dh,
+ h_errno == TRY_AGAIN ? errval : 0, ttl);
+ scratch_buffer_free (&tmpbuf);
+ return timeout;
}
}
-void
+time_t
readdhstbyname (struct database_dyn *db, struct hashentry *he,
struct datahead *dh)
{
.key_len = he->len
};
- addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
+ return addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
}
}
-void
+time_t
readdhstbyaddr (struct database_dyn *db, struct hashentry *he,
struct datahead *dh)
{
.key_len = he->len
};
- addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
+ return addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
}
}
-void
+time_t
readdhstbynamev6 (struct database_dyn *db, struct hashentry *he,
struct datahead *dh)
{
.key_len = he->len
};
- addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
+ return addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
}
}
-void
+time_t
readdhstbyaddrv6 (struct database_dyn *db, struct hashentry *he,
struct datahead *dh)
{
.key_len = he->len
};
- addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
+ return addhstbyX (db, -1, &req, db->data + he->key, he->owner, he, dh);
}
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