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glibc/nscd/aicache.c
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/* Cache handling for host lookup. | |
Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
Contributed by Ulrich Drepper <drepper@redhat.com>, 2004. | |
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 <assert.h> | |
#include <errno.h> | |
#include <libintl.h> | |
#include <netdb.h> | |
#include <string.h> | |
#include <time.h> | |
#include <unistd.h> | |
#include <sys/mman.h> | |
#include "dbg_log.h" | |
#include "nscd.h" | |
#ifdef HAVE_SENDFILE | |
# include <kernel-features.h> | |
#endif | |
typedef enum nss_status (*nss_gethostbyname3_r) | |
(const char *name, int af, struct hostent *host, | |
char *buffer, size_t buflen, int *errnop, | |
int *h_errnop, int32_t *, char **); | |
typedef enum nss_status (*nss_getcanonname_r) | |
(const char *name, char *buffer, size_t buflen, char **result, | |
int *errnop, int *h_errnop); | |
static const ai_response_header notfound = | |
{ | |
.version = NSCD_VERSION, | |
.found = 0, | |
.naddrs = 0, | |
.addrslen = 0, | |
.canonlen = 0, | |
.error = 0 | |
}; | |
static void | |
addhstaiX (struct database_dyn *db, int fd, request_header *req, | |
void *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. */ | |
/* We allocate all data in one memory block: the iov vector, | |
the response header and the dataset itself. */ | |
struct dataset | |
{ | |
struct datahead head; | |
ai_response_header resp; | |
char strdata[0]; | |
} *dataset = NULL; | |
if (__builtin_expect (debug_level > 0, 0)) | |
{ | |
if (he == NULL) | |
dbg_log (_("Haven't found \"%s\" in hosts cache!"), (char *) key); | |
else | |
dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) key); | |
} | |
static service_user *hosts_database; | |
service_user *nip = NULL; | |
int no_more; | |
int rc6 = 0; | |
int rc4 = 0; | |
int herrno = 0; | |
if (hosts_database != NULL) | |
{ | |
nip = hosts_database; | |
no_more = 0; | |
} | |
else | |
no_more = __nss_database_lookup ("hosts", NULL, | |
"dns [!UNAVAIL=return] files", &nip); | |
if (__res_maybe_init (&_res, 0) == -1) | |
no_more = 1; | |
/* If we are looking for both IPv4 and IPv6 address we don't want | |
the lookup functions to automatically promote IPv4 addresses to | |
IPv6 addresses. Currently this is decided by setting the | |
RES_USE_INET6 bit in _res.options. */ | |
int old_res_options = _res.options; | |
_res.options &= ~RES_USE_INET6; | |
size_t tmpbuf6len = 512; | |
char *tmpbuf6 = alloca (tmpbuf6len); | |
size_t tmpbuf4len = 0; | |
char *tmpbuf4 = NULL; | |
char *canon = NULL; | |
int32_t ttl = UINT32_MAX; | |
ssize_t total = 0; | |
char *key_copy = NULL; | |
bool alloca_used = false; | |
while (!no_more) | |
{ | |
int status[2] = { NSS_STATUS_UNAVAIL, NSS_STATUS_UNAVAIL }; | |
/* Prefer the function which also returns the TTL and canonical name. */ | |
nss_gethostbyname3_r fct = __nss_lookup_function (nip, | |
"gethostbyname3_r"); | |
if (fct == NULL) | |
fct = __nss_lookup_function (nip, "gethostbyname2_r"); | |
if (fct != NULL) | |
{ | |
struct hostent th[2]; | |
/* Collect IPv6 information first. */ | |
while (1) | |
{ | |
rc6 = 0; | |
status[0] = DL_CALL_FCT (fct, (key, AF_INET6, &th[0], tmpbuf6, | |
tmpbuf6len, &rc6, &herrno, | |
&ttl, &canon)); | |
if (rc6 != ERANGE || herrno != NETDB_INTERNAL) | |
break; | |
tmpbuf6 = extend_alloca (tmpbuf6, tmpbuf6len, 2 * tmpbuf6len); | |
} | |
if (rc6 != 0 && herrno == NETDB_INTERNAL) | |
goto out; | |
/* If the IPv6 lookup has been successful do not use the | |
buffer used in that lookup, use a new one. */ | |
if (status[0] == NSS_STATUS_SUCCESS && rc6 == 0) | |
{ | |
tmpbuf4len = 512; | |
tmpbuf4 = alloca (tmpbuf4len); | |
} | |
else | |
{ | |
tmpbuf4len = tmpbuf6len; | |
tmpbuf4 = tmpbuf6; | |
} | |
/* Next collect IPv4 information first. */ | |
while (1) | |
{ | |
rc4 = 0; | |
status[1] = DL_CALL_FCT (fct, (key, AF_INET, &th[1], tmpbuf4, | |
tmpbuf4len, &rc4, &herrno, | |
ttl == UINT32_MAX ? &ttl : NULL, | |
canon == NULL ? &canon : NULL)); | |
if (rc4 != ERANGE || herrno != NETDB_INTERNAL) | |
break; | |
tmpbuf4 = extend_alloca (tmpbuf4, tmpbuf4len, 2 * tmpbuf4len); | |
} | |
if (rc4 != 0 || herrno == NETDB_INTERNAL) | |
goto out; | |
if (status[0] == NSS_STATUS_SUCCESS | |
|| status[1] == NSS_STATUS_SUCCESS) | |
{ | |
/* We found the data. Count the addresses and the size. */ | |
int naddrs = 0; | |
size_t addrslen = 0; | |
for (int j = 0; j < 2; ++j) | |
if (status[j] == NSS_STATUS_SUCCESS) | |
for (int i = 0; th[j].h_addr_list[i] != NULL; ++i) | |
{ | |
++naddrs; | |
addrslen += th[j].h_length; | |
} | |
if (canon == NULL) | |
{ | |
/* Determine the canonical name. */ | |
nss_getcanonname_r cfct; | |
cfct = __nss_lookup_function (nip, "getcanonname_r"); | |
if (cfct != NULL) | |
{ | |
const size_t max_fqdn_len = 256; | |
char *buf = alloca (max_fqdn_len); | |
char *s; | |
int rc; | |
if (DL_CALL_FCT (cfct, (key, buf, max_fqdn_len, &s, &rc, | |
&herrno)) == NSS_STATUS_SUCCESS) | |
canon = s; | |
else | |
/* Set to name now to avoid using gethostbyaddr. */ | |
canon = key; | |
} | |
else | |
{ | |
struct hostent *he = NULL; | |
int herrno; | |
struct hostent he_mem; | |
void *addr; | |
size_t addrlen; | |
int addrfamily; | |
if (status[1] == NSS_STATUS_SUCCESS) | |
{ | |
addr = th[1].h_addr_list[0]; | |
addrlen = sizeof (struct in_addr); | |
addrfamily = AF_INET; | |
} | |
else | |
{ | |
addr = th[0].h_addr_list[0]; | |
addrlen = sizeof (struct in6_addr); | |
addrfamily = AF_INET6; | |
} | |
size_t tmpbuflen = 512; | |
char *tmpbuf = alloca (tmpbuflen); | |
int rc; | |
while (1) | |
{ | |
rc = __gethostbyaddr_r (addr, addrlen, addrfamily, | |
&he_mem, tmpbuf, tmpbuflen, | |
&he, &herrno); | |
if (rc != ERANGE || herrno != NETDB_INTERNAL) | |
break; | |
tmpbuf = extend_alloca (tmpbuf, tmpbuflen, | |
tmpbuflen * 2); | |
} | |
if (rc == 0) | |
{ | |
if (he != NULL) | |
canon = he->h_name; | |
else | |
canon = key; | |
} | |
} | |
} | |
size_t canonlen = canon == NULL ? 0 : (strlen (canon) + 1); | |
total = sizeof (*dataset) + naddrs + addrslen + canonlen; | |
/* Now we can allocate the data structure. If the TTL | |
of the entry is reported as zero do not cache the | |
entry at all. */ | |
if (ttl != 0 && 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 = time (NULL) + MIN (db->postimeout, ttl); | |
dataset->resp.version = NSCD_VERSION; | |
dataset->resp.found = 1; | |
dataset->resp.naddrs = naddrs; | |
dataset->resp.addrslen = addrslen; | |
dataset->resp.canonlen = canonlen; | |
dataset->resp.error = NETDB_SUCCESS; | |
char *addrs = (char *) (&dataset->resp + 1); | |
uint8_t *family = (uint8_t *) (addrs + addrslen); | |
for (int j = 0; j < 2; ++j) | |
if (status[j] == NSS_STATUS_SUCCESS) | |
for (int i = 0; th[j].h_addr_list[i] != NULL; ++i) | |
{ | |
addrs = mempcpy (addrs, th[j].h_addr_list[i], | |
th[j].h_length); | |
*family++ = th[j].h_addrtype; | |
} | |
void *cp = family; | |
if (canon != NULL) | |
cp = mempcpy (cp, canon, canonlen); | |
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 pointer into the memory block. */ | |
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 let the receiver | |
wait. */ | |
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)); | |
ssize_t written; | |
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 | |
writeall (fd, &dataset->resp, total); | |
} | |
goto out; | |
} | |
} | |
if (nss_next_action (nip, status[1]) == NSS_ACTION_RETURN) | |
break; | |
if (nip->next == NULL) | |
no_more = -1; | |
else | |
nip = nip->next; | |
} | |
/* No result found. Create a negative result record. */ | |
if (he != NULL && rc4 == 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 && dh->nreloads == reload_count) | |
/* Do not reset the value if we never not reload the record. */ | |
dh->nreloads = reload_count - 1; | |
} | |
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)); | |
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 = time (NULL) + db->negtimeout; | |
/* This is the reply. */ | |
memcpy (&dataset->resp, ¬found, total); | |
/* Copy the key data. */ | |
key_copy = memcpy (dataset->strdata, key, req->key_len); | |
} | |
else | |
++db->head->addfailed; | |
} | |
out: | |
_res.options = old_res_options; | |
if (dataset != NULL && !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, uid) < 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; | |
} | |
} | |
void | |
addhstai (struct database_dyn *db, int fd, request_header *req, void *key, | |
uid_t uid) | |
{ | |
addhstaiX (db, fd, req, key, uid, NULL, NULL); | |
} | |
void | |
readdhstai (struct database_dyn *db, struct hashentry *he, struct datahead *dh) | |
{ | |
request_header req = | |
{ | |
.type = GETAI, | |
.key_len = he->len | |
}; | |
addhstaiX (db, -1, &req, db->data + he->key, he->owner, he, dh); | |
} |