/* Copyright (C) 1998-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
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
<http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <resolv/resolv-internal.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <arpa/nameser.h>
#include <not-cancel.h>
#include "nscd-client.h"
#include "nscd_proto.h"
int __nss_not_use_nscd_hosts;
static int nscd_gethst_r (const char *key, size_t keylen, request_type type,
struct hostent *resultbuf, char *buffer,
size_t buflen, struct hostent **result,
int *h_errnop);
int
__nscd_gethostbyname_r (const char *name, struct hostent *resultbuf,
char *buffer, size_t buflen, struct hostent **result,
int *h_errnop)
{
request_type reqtype;
reqtype = res_use_inet6 () ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;
return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
buffer, buflen, result, h_errnop);
}
int
__nscd_gethostbyname2_r (const char *name, int af, struct hostent *resultbuf,
char *buffer, size_t buflen, struct hostent **result,
int *h_errnop)
{
request_type reqtype;
reqtype = af == AF_INET6 ? GETHOSTBYNAMEv6 : GETHOSTBYNAME;
return nscd_gethst_r (name, strlen (name) + 1, reqtype, resultbuf,
buffer, buflen, result, h_errnop);
}
int
__nscd_gethostbyaddr_r (const void *addr, socklen_t len, int type,
struct hostent *resultbuf, char *buffer, size_t buflen,
struct hostent **result, int *h_errnop)
{
request_type reqtype;
if (!((len == INADDRSZ && type == AF_INET)
|| (len == IN6ADDRSZ && type == AF_INET6)))
/* LEN and TYPE do not match. */
return -1;
reqtype = type == AF_INET6 ? GETHOSTBYADDRv6 : GETHOSTBYADDR;
return nscd_gethst_r (addr, len, reqtype, resultbuf, buffer, buflen, result,
h_errnop);
}
libc_locked_map_ptr (, __hst_map_handle) attribute_hidden;
/* Note that we only free the structure if necessary. The memory
mapping is not removed since it is not visible to the malloc
handling. */
libc_freeres_fn (hst_map_free)
{
if (__hst_map_handle.mapped != NO_MAPPING)
{
void *p = __hst_map_handle.mapped;
__hst_map_handle.mapped = NO_MAPPING;
free (p);
}
}
uint32_t
__nscd_get_nl_timestamp (void)
{
uint32_t retval;
if (__nss_not_use_nscd_hosts != 0)
return 0;
/* __nscd_get_mapping can change hst_map_handle.mapped to NO_MAPPING.
However, __nscd_get_mapping assumes the prior value was not NO_MAPPING.
Thus we have to acquire the lock to prevent this thread from changing
hst_map_handle.mapped to NO_MAPPING while another thread is inside
__nscd_get_mapping. */
if (!__nscd_acquire_maplock (&__hst_map_handle))
return 0;
struct mapped_database *map = __hst_map_handle.mapped;
if (map == NULL
|| (map != NO_MAPPING
&& map->head->nscd_certainly_running == 0
&& map->head->timestamp + MAPPING_TIMEOUT < time (NULL)))
map = __nscd_get_mapping (GETFDHST, "hosts", &__hst_map_handle.mapped);
if (map == NO_MAPPING)
retval = 0;
else
retval = map->head->extra_data[NSCD_HST_IDX_CONF_TIMESTAMP];
/* Release the lock. */
__hst_map_handle.lock = 0;
return retval;
}
int __nss_have_localdomain attribute_hidden;
static int
nscd_gethst_r (const char *key, size_t keylen, request_type type,
struct hostent *resultbuf, char *buffer, size_t buflen,
struct hostent **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;
}
}
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:;
const char *h_name = NULL;
const uint32_t *aliases_len = NULL;
const char *addr_list = NULL;
size_t addr_list_len = 0;
int retval = -1;
const char *recend = (const char *) ~UINTMAX_C (0);
int sock = -1;
hst_response_header hst_resp;
if (mapped != NO_MAPPING)
{
/* No const qualifier, as it can change during garbage collection. */
struct datahead *found = __nscd_cache_search (type, key, keylen, mapped,
sizeof hst_resp);
if (found != NULL)
{
h_name = (char *) (&found->data[0].hstdata + 1);
hst_resp = found->data[0].hstdata;
aliases_len = (uint32_t *) (h_name + hst_resp.h_name_len);
addr_list = ((char *) aliases_len
+ hst_resp.h_aliases_cnt * sizeof (uint32_t));
addr_list_len = hst_resp.h_addr_list_cnt * INADDRSZ;
recend = (const char *) found->data + found->recsize;
/* Now check if we can trust hst_resp fields. If GC is
in progress, it can contain anything. */
if (mapped->head->gc_cycle != gc_cycle)
{
retval = -2;
goto out;
}
#if !_STRING_ARCH_unaligned
/* The aliases_len array in the mapped database might very
well be unaligned. We will access it word-wise so on
platforms which do not tolerate unaligned accesses we
need to make an aligned copy. */
if (((uintptr_t) aliases_len & (__alignof__ (*aliases_len) - 1))
!= 0)
{
uint32_t *tmp = alloca (hst_resp.h_aliases_cnt
* sizeof (uint32_t));
aliases_len = memcpy (tmp, aliases_len,
hst_resp.h_aliases_cnt
* sizeof (uint32_t));
}
#endif
if (type != GETHOSTBYADDR && type != GETHOSTBYNAME)
{
if (hst_resp.h_length == INADDRSZ)
addr_list += addr_list_len;
addr_list_len = hst_resp.h_addr_list_cnt * IN6ADDRSZ;
}
if (__builtin_expect ((const char *) addr_list + addr_list_len
> recend, 0))
goto out;
}
}
if (h_name == NULL)
{
sock = __nscd_open_socket (key, keylen, type, &hst_resp,
sizeof (hst_resp));
if (sock == -1)
{
__nss_not_use_nscd_hosts = 1;
goto out;
}
}
/* No value found so far. */
*result = NULL;
if (__glibc_unlikely (hst_resp.found == -1))
{
/* The daemon does not cache this database. */
__nss_not_use_nscd_hosts = 1;
goto out_close;
}
if (hst_resp.found == 1)
{
char *cp = buffer;
uintptr_t align1;
uintptr_t align2;
size_t total_len;
ssize_t cnt;
char *ignore;
int n;
/* A first check whether the buffer is sufficiently large is possible. */
/* Now allocate the buffer the array for the group members. We must
align the pointer and the base of the h_addr_list pointers. */
align1 = ((__alignof__ (char *) - (cp - ((char *) 0)))
& (__alignof__ (char *) - 1));
align2 = ((__alignof__ (char *) - ((cp + align1 + hst_resp.h_name_len)
- ((char *) 0)))
& (__alignof__ (char *) - 1));
if (buflen < (align1 + hst_resp.h_name_len + align2
+ ((hst_resp.h_aliases_cnt + hst_resp.h_addr_list_cnt
+ 2)
* sizeof (char *))
+ hst_resp.h_addr_list_cnt * (type == AF_INET
? INADDRSZ : IN6ADDRSZ)))
{
no_room:
*h_errnop = NETDB_INTERNAL;
__set_errno (ERANGE);
retval = ERANGE;
goto out_close;
}
cp += align1;
/* Prepare the result as far as we can. */
resultbuf->h_aliases = (char **) cp;
cp += (hst_resp.h_aliases_cnt + 1) * sizeof (char *);
resultbuf->h_addr_list = (char **) cp;
cp += (hst_resp.h_addr_list_cnt + 1) * sizeof (char *);
resultbuf->h_name = cp;
cp += hst_resp.h_name_len + align2;
if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
{
resultbuf->h_addrtype = AF_INET;
resultbuf->h_length = INADDRSZ;
}
else
{
resultbuf->h_addrtype = AF_INET6;
resultbuf->h_length = IN6ADDRSZ;
}
for (cnt = 0; cnt < hst_resp.h_addr_list_cnt; ++cnt)
{
resultbuf->h_addr_list[cnt] = cp;
cp += resultbuf->h_length;
}
resultbuf->h_addr_list[cnt] = NULL;
if (h_name == NULL)
{
struct iovec vec[4];
vec[0].iov_base = resultbuf->h_name;
vec[0].iov_len = hst_resp.h_name_len;
total_len = hst_resp.h_name_len;
n = 1;
if (hst_resp.h_aliases_cnt > 0)
{
aliases_len = alloca (hst_resp.h_aliases_cnt
* sizeof (uint32_t));
vec[n].iov_base = (void *) aliases_len;
vec[n].iov_len = hst_resp.h_aliases_cnt * sizeof (uint32_t);
total_len += hst_resp.h_aliases_cnt * sizeof (uint32_t);
++n;
}
if (type == GETHOSTBYADDR || type == GETHOSTBYNAME)
{
vec[n].iov_base = resultbuf->h_addr_list[0];
vec[n].iov_len = hst_resp.h_addr_list_cnt * INADDRSZ;
total_len += hst_resp.h_addr_list_cnt * INADDRSZ;
++n;
}
else
{
if (hst_resp.h_length == INADDRSZ)
{
ignore = alloca (hst_resp.h_addr_list_cnt * INADDRSZ);
vec[n].iov_base = ignore;
vec[n].iov_len = hst_resp.h_addr_list_cnt * INADDRSZ;
total_len += hst_resp.h_addr_list_cnt * INADDRSZ;
++n;
}
vec[n].iov_base = resultbuf->h_addr_list[0];
vec[n].iov_len = hst_resp.h_addr_list_cnt * IN6ADDRSZ;
total_len += hst_resp.h_addr_list_cnt * IN6ADDRSZ;
++n;
}
if ((size_t) __readvall (sock, vec, n) != total_len)
goto out_close;
}
else
{
memcpy (resultbuf->h_name, h_name, hst_resp.h_name_len);
memcpy (resultbuf->h_addr_list[0], addr_list, addr_list_len);
}
/* Now we also can read the aliases. */
total_len = 0;
for (cnt = 0; cnt < hst_resp.h_aliases_cnt; ++cnt)
{
resultbuf->h_aliases[cnt] = cp;
cp += aliases_len[cnt];
total_len += aliases_len[cnt];
}
resultbuf->h_aliases[cnt] = NULL;
if (__builtin_expect ((const char *) addr_list + addr_list_len
+ total_len > recend, 0))
{
/* aliases_len array might contain garbage during nscd GC cycle,
retry rather than fail in that case. */
if (addr_list != NULL && mapped->head->gc_cycle != gc_cycle)
retval = -2;
goto out_close;
}
/* See whether this would exceed the buffer capacity. */
if (__glibc_unlikely (cp > buffer + buflen))
{
/* aliases_len array might contain garbage during nscd GC cycle,
retry rather than fail in that case. */
if (addr_list != NULL && mapped->head->gc_cycle != gc_cycle)
{
retval = -2;
goto out_close;
}
goto no_room;
}
/* And finally read the aliases. */
if (addr_list == NULL)
{
if (total_len == 0
|| ((size_t) __readall (sock, resultbuf->h_aliases[0], total_len)
== total_len))
{
retval = 0;
*result = resultbuf;
}
}
else
{
memcpy (resultbuf->h_aliases[0],
(const char *) addr_list + addr_list_len, total_len);
/* Try to detect corrupt databases. */
if (resultbuf->h_name[hst_resp.h_name_len - 1] != '\0'
|| ({for (cnt = 0; cnt < hst_resp.h_aliases_cnt; ++cnt)
if (resultbuf->h_aliases[cnt][aliases_len[cnt] - 1]
!= '\0')
break;
cnt < hst_resp.h_aliases_cnt; }))
{
/* We cannot use the database. */
if (mapped->head->gc_cycle != gc_cycle)
retval = -2;
goto out_close;
}
retval = 0;
*result = resultbuf;
}
}
else
{
/* Store the error number. */
*h_errnop = hst_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_decrement_val (&mapped->counter) == 0)
__nscd_unmap (mapped);
mapped = NO_MAPPING;
}
if (retval != -1)
goto retry;
}
return retval;
}