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/* Copyright (C) 2004-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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, see
<https://www.gnu.org/licenses/>. */
#include <assert.h>
#include <errno.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <not-cancel.h>
#include "nscd-client.h"
#include "nscd_proto.h"
/* Define in nscd_gethst_r.c. */
extern int __nss_not_use_nscd_hosts;
/* We use the mapping from nscd_gethst. */
libc_locked_map_ptr (extern, __hst_map_handle) attribute_hidden;
/* Defined in nscd_gethst_r.c. */
extern int __nss_have_localdomain attribute_hidden;
int
__nscd_getai (const char *key, struct nscd_ai_result **result, int *h_errnop)
{
if (__glibc_unlikely (__nss_have_localdomain >= 0))
{
if (__nss_have_localdomain == 0)
__nss_have_localdomain = getenv ("LOCALDOMAIN") != NULL ? 1 : -1;
if (__nss_have_localdomain > 0)
{
__nss_not_use_nscd_hosts = 1;
return -1;
}
}
size_t keylen = strlen (key) + 1;
int gc_cycle;
int nretries = 0;
/* If the mapping is available, try to search there instead of
communicating with the nscd. */
struct mapped_database *mapped;
mapped = __nscd_get_map_ref (GETFDHST, "hosts", &__hst_map_handle,
&gc_cycle);
retry:;
struct nscd_ai_result *resultbuf = NULL;
const char *recend = (const char *) ~UINTMAX_C (0);
char *respdata = NULL;
int retval = -1;
int sock = -1;
ai_response_header ai_resp;
if (mapped != NO_MAPPING)
{
struct datahead *found = __nscd_cache_search (GETAI, key, keylen,
mapped, sizeof ai_resp);
if (found != NULL)
{
respdata = (char *) (&found->data[0].aidata + 1);
ai_resp = found->data[0].aidata;
recend = (const char *) found->data + found->recsize;
/* Now check if we can trust ai_resp fields. If GC is
in progress, it can contain anything. */
if (mapped->head->gc_cycle != gc_cycle)
{
retval = -2;
goto out;
}
}
}
/* If we do not have the cache mapped, try to get the data over the
socket. */
if (respdata == NULL)
{
sock = __nscd_open_socket (key, keylen, GETAI, &ai_resp,
sizeof (ai_resp));
if (sock == -1)
{
/* nscd not running or wrong version. */
__nss_not_use_nscd_hosts = 1;
goto out;
}
}
if (ai_resp.found == 1)
{
size_t datalen = ai_resp.naddrs + ai_resp.addrslen + ai_resp.canonlen;
/* This check really only affects the case where the data
comes from the mapped cache. */
if (respdata + datalen > recend)
{
assert (sock == -1);
goto out;
}
/* Create result. */
resultbuf = (struct nscd_ai_result *) malloc (sizeof (*resultbuf)
+ datalen);
if (resultbuf == NULL)
{
*h_errnop = NETDB_INTERNAL;
goto out_close;
}
/* Set up the data structure, including pointers. */
resultbuf->naddrs = ai_resp.naddrs;
resultbuf->addrs = (char *) (resultbuf + 1);
resultbuf->family = (uint8_t *) (resultbuf->addrs + ai_resp.addrslen);
if (ai_resp.canonlen != 0)
resultbuf->canon = (char *) (resultbuf->family + resultbuf->naddrs);
else
resultbuf->canon = NULL;
if (respdata == NULL)
{
/* Read the data from the socket. */
if ((size_t) __readall (sock, resultbuf + 1, datalen) == datalen)
{
retval = 0;
*result = resultbuf;
}
else
{
free (resultbuf);
*h_errnop = NETDB_INTERNAL;
}
}
else
{
/* Copy the data in the block. */
memcpy (resultbuf + 1, respdata, datalen);
/* Try to detect corrupt databases. */
if (resultbuf->canon != NULL
&& resultbuf->canon[ai_resp.canonlen - 1] != '\0')
/* We cannot use the database. */
{
if (mapped->head->gc_cycle != gc_cycle)
retval = -2;
else
free (resultbuf);
goto out_close;
}
retval = 0;
*result = resultbuf;
}
}
else
{
if (__glibc_unlikely (ai_resp.found == -1))
{
/* The daemon does not cache this database. */
__nss_not_use_nscd_hosts = 1;
goto out_close;
}
/* Store the error number. */
*h_errnop = ai_resp.error;
/* Set errno to 0 to indicate no error, just no found record. */
__set_errno (0);
/* Even though we have not found anything, the result is zero. */
retval = 0;
}
out_close:
if (sock != -1)
__close_nocancel_nostatus (sock);
out:
if (__nscd_drop_map_ref (mapped, &gc_cycle) != 0)
{
/* When we come here this means there has been a GC cycle while we
were looking for the data. This means the data might have been
inconsistent. Retry if possible. */
if ((gc_cycle & 1) != 0 || ++nretries == 5 || retval == -1)
{
/* nscd is just running gc now. Disable using the mapping. */
if (atomic_fetch_add_relaxed (&mapped->counter, -1) == 1)
__nscd_unmap (mapped);
mapped = NO_MAPPING;
}
if (retval != -1)
{
*result = NULL;
free (resultbuf);
goto retry;
}
}
return retval;
}
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