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-rw-r--r--nscd/aicache.c428
1 files changed, 428 insertions, 0 deletions
diff --git a/nscd/aicache.c b/nscd/aicache.c
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+/* Cache handling for host lookup.
+ Copyright (C) 2004 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Ulrich Drepper <drepper@redhat.com>, 2004.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; 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>
+
+
+typedef enum nss_status (*nss_gethostbyname2_r)
+ (const char *name, int af, struct hostent *host,
+ char *buffer, size_t buflen, int *errnop,
+ int *h_errnop);
+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. */
+ uid_t oldeuid = 0;
+
+ /* 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);
+ }
+
+ if (db->secure)
+ {
+ oldeuid = geteuid ();
+ seteuid (uid);
+ }
+
+ 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;
+ ssize_t total = 0;
+ char *key_copy = NULL;
+ bool alloca_used = false;
+
+ while (!no_more)
+ {
+ nss_gethostbyname2_r fct = __nss_lookup_function (nip,
+ "gethostbyname2_r");
+ int status[2] = { NSS_STATUS_UNAVAIL, NSS_STATUS_UNAVAIL };
+
+ if (fct != NULL)
+ {
+ printf("fct=%p\n",fct);
+ 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));
+ 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));
+ if (rc4 != ERANGE || herrno != NETDB_INTERNAL)
+ break;
+ tmpbuf4 = extend_alloca (tmpbuf6, tmpbuf6len, 2 * tmpbuf6len);
+ }
+
+ 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;
+ }
+
+ /* 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
+ {
+ // XXX use gethostbyaddr
+ }
+ size_t canonlen = canon == NULL ? 0 : (strlen (canon) + 1);
+
+ total = sizeof (*dataset) + naddrs + addrslen + canonlen;
+
+ /* Now we can allocate the data structure. */
+ 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 = time (NULL) + db->postimeout;
+
+ 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;
+ }
+
+ char *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);
+
+ TEMP_FAILURE_RETRY (write (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 (write (fd, &notfound, total));
+
+ 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, &notfound, 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 (db->secure)
+ seteuid (oldeuid);
+
+ 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);
+}
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