/* Hosts file parser in nss_files module.
Copyright (C) 1996-2018 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
<http://www.gnu.org/licenses/>. */
#include <assert.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <netdb.h>
#include <resolv/resolv-internal.h>
#include <scratch_buffer.h>
#include <alloc_buffer.h>
/* Get implementation for some internal functions. */
#include "../resolv/mapv4v6addr.h"
#include "../resolv/res_hconf.h"
#define ENTNAME hostent
#define DATABASE "hosts"
#define NEED_H_ERRNO
#define EXTRA_ARGS , af, flags
#define EXTRA_ARGS_DECL , int af, int flags
#define ENTDATA hostent_data
struct hostent_data
{
unsigned char host_addr[16]; /* IPv4 or IPv6 address. */
char *h_addr_ptrs[2]; /* Points to that and null terminator. */
};
#define TRAILING_LIST_MEMBER h_aliases
#define TRAILING_LIST_SEPARATOR_P isspace
#include "files-parse.c"
LINE_PARSER
("#",
{
char *addr;
STRING_FIELD (addr, isspace, 1);
/* Parse address. */
if (inet_pton (af == AF_UNSPEC ? AF_INET : af, addr, entdata->host_addr)
> 0)
af = af == AF_UNSPEC ? AF_INET : af;
else
{
if (af == AF_INET6 && (flags & AI_V4MAPPED) != 0
&& inet_pton (AF_INET, addr, entdata->host_addr) > 0)
map_v4v6_address ((char *) entdata->host_addr,
(char *) entdata->host_addr);
else if (af == AF_INET
&& inet_pton (AF_INET6, addr, entdata->host_addr) > 0)
{
if (IN6_IS_ADDR_V4MAPPED (entdata->host_addr))
memcpy (entdata->host_addr, entdata->host_addr + 12, INADDRSZ);
else if (IN6_IS_ADDR_LOOPBACK (entdata->host_addr))
{
in_addr_t localhost = htonl (INADDR_LOOPBACK);
memcpy (entdata->host_addr, &localhost, sizeof (localhost));
}
else
/* Illegal address: ignore line. */
return 0;
}
else if (af == AF_UNSPEC
&& inet_pton (AF_INET6, addr, entdata->host_addr) > 0)
af = AF_INET6;
else
/* Illegal address: ignore line. */
return 0;
}
/* We always return entries of the requested form. */
result->h_addrtype = af;
result->h_length = af == AF_INET ? INADDRSZ : IN6ADDRSZ;
/* Store a pointer to the address in the expected form. */
entdata->h_addr_ptrs[0] = (char *) entdata->host_addr;
entdata->h_addr_ptrs[1] = NULL;
result->h_addr_list = entdata->h_addr_ptrs;
STRING_FIELD (result->h_name, isspace, 1);
})
#define EXTRA_ARGS_VALUE \
, (res_use_inet6 () ? AF_INET6 : AF_INET), \
(res_use_inet6 () ? AI_V4MAPPED : 0)
#include "files-XXX.c"
#undef EXTRA_ARGS_VALUE
/* We only need to consider IPv4 mapped addresses if the input to the
gethostbyaddr() function is an IPv6 address. */
#define EXTRA_ARGS_VALUE \
, af, (len == IN6ADDRSZ ? AI_V4MAPPED : 0)
DB_LOOKUP (hostbyaddr, ,,,
{
if (result->h_length == (int) len
&& ! memcmp (addr, result->h_addr_list[0], len))
break;
}, const void *addr, socklen_t len, int af)
#undef EXTRA_ARGS_VALUE
/* Type of the address and alias arrays. */
#define DYNARRAY_STRUCT array
#define DYNARRAY_ELEMENT char *
#define DYNARRAY_PREFIX array_
#include <malloc/dynarray-skeleton.c>
static enum nss_status
gethostbyname3_multi (FILE * stream, const char *name, int af,
struct hostent *result, char *buffer, size_t buflen,
int *errnop, int *herrnop, int flags)
{
assert (af == AF_INET || af == AF_INET6);
/* We have to get all host entries from the file. */
struct scratch_buffer tmp_buffer;
scratch_buffer_init (&tmp_buffer);
struct hostent tmp_result_buf;
struct array addresses;
array_init (&addresses);
struct array aliases;
array_init (&aliases);
enum nss_status status;
/* Preserve the addresses and aliases encountered so far. */
for (size_t i = 0; result->h_addr_list[i] != NULL; ++i)
array_add (&addresses, result->h_addr_list[i]);
for (size_t i = 0; result->h_aliases[i] != NULL; ++i)
array_add (&aliases, result->h_aliases[i]);
/* The output buffer re-uses now-unused space at the end of the
buffer, starting with the aliases array. It comes last in the
data produced by internal_getent. (The alias names themselves
are still located in the line read in internal_getent, which is
stored at the beginning of the buffer.) */
struct alloc_buffer outbuf;
{
char *bufferend = (char *) result->h_aliases;
outbuf = alloc_buffer_create (bufferend, buffer + buflen - bufferend);
}
while (true)
{
status = internal_getent (stream, &tmp_result_buf, tmp_buffer.data,
tmp_buffer.length, errnop, herrnop, af,
flags);
/* Enlarge the buffer if necessary. */
if (status == NSS_STATUS_TRYAGAIN && *herrnop == NETDB_INTERNAL
&& *errnop == ERANGE)
{
if (!scratch_buffer_grow (&tmp_buffer))
{
*errnop = ENOMEM;
/* *herrnop and status already have the right value. */
break;
}
/* Loop around and retry with a larger buffer. */
}
else if (status == NSS_STATUS_SUCCESS)
{
/* A line was read. Check that it matches the search
criteria. */
int matches = 1;
struct hostent *old_result = result;
result = &tmp_result_buf;
/* The following piece is a bit clumsy but we want to use
the `LOOKUP_NAME_CASE' value. The optimizer should do
its job. */
do
{
LOOKUP_NAME_CASE (h_name, h_aliases)
result = old_result;
}
while ((matches = 0));
/* If the line matches, we need to copy the addresses and
aliases, so that we can reuse tmp_buffer for the next
line. */
if (matches)
{
/* Record the addresses. */
for (size_t i = 0; tmp_result_buf.h_addr_list[i] != NULL; ++i)
{
/* Allocate the target space in the output buffer,
depending on the address family. */
void *target;
if (af == AF_INET)
{
assert (tmp_result_buf.h_length == 4);
target = alloc_buffer_alloc (&outbuf, struct in_addr);
}
else if (af == AF_INET6)
{
assert (tmp_result_buf.h_length == 16);
target = alloc_buffer_alloc (&outbuf, struct in6_addr);
}
else
__builtin_unreachable ();
if (target == NULL)
{
/* Request a larger output buffer. */
*errnop = ERANGE;
*herrnop = NETDB_INTERNAL;
status = NSS_STATUS_TRYAGAIN;
break;
}
memcpy (target, tmp_result_buf.h_addr_list[i],
tmp_result_buf.h_length);
array_add (&addresses, target);
}
/* Record the aliases. */
for (size_t i = 0; tmp_result_buf.h_aliases[i] != NULL; ++i)
{
char *alias = tmp_result_buf.h_aliases[i];
array_add (&aliases,
alloc_buffer_copy_string (&outbuf, alias));
}
/* If the real name is different add, it also to the
aliases. This means that there is a duplication in
the alias list but this is really the user's
problem. */
{
char *new_name = tmp_result_buf.h_name;
if (strcmp (old_result->h_name, new_name) != 0)
array_add (&aliases,
alloc_buffer_copy_string (&outbuf, new_name));
}
/* Report memory allocation failures during the
expansion of the temporary arrays. */
if (array_has_failed (&addresses) || array_has_failed (&aliases))
{
*errnop = ENOMEM;
*herrnop = NETDB_INTERNAL;
status = NSS_STATUS_UNAVAIL;
break;
}
/* Request a larger output buffer if we ran out of room. */
if (alloc_buffer_has_failed (&outbuf))
{
*errnop = ERANGE;
*herrnop = NETDB_INTERNAL;
status = NSS_STATUS_TRYAGAIN;
break;
}
result = old_result;
} /* If match was found. */
/* If no match is found, loop around and fetch another
line. */
} /* status == NSS_STATUS_SUCCESS. */
else
/* internal_getent returned an error. */
break;
} /* while (true) */
/* Propagate the NSS_STATUS_TRYAGAIN error to the caller. It means
that we may not have loaded the complete result.
NSS_STATUS_NOTFOUND, however, means that we reached the end of
the file successfully. */
if (status != NSS_STATUS_TRYAGAIN)
status = NSS_STATUS_SUCCESS;
if (status == NSS_STATUS_SUCCESS)
{
/* Copy the address and alias arrays into the output buffer and
add NULL terminators. The pointed-to elements were directly
written into the output buffer above and do not need to be
copied again. */
size_t addresses_count = array_size (&addresses);
size_t aliases_count = array_size (&aliases);
char **out_addresses = alloc_buffer_alloc_array
(&outbuf, char *, addresses_count + 1);
char **out_aliases = alloc_buffer_alloc_array
(&outbuf, char *, aliases_count + 1);
if (out_addresses == NULL || out_aliases == NULL)
{
/* The output buffer is not large enough. */
*errnop = ERANGE;
*herrnop = NETDB_INTERNAL;
status = NSS_STATUS_TRYAGAIN;
/* Fall through to function exit. */
}
else
{
/* Everything is allocated in place. Make the copies and
adjust the array pointers. */
memcpy (out_addresses, array_begin (&addresses),
addresses_count * sizeof (char *));
out_addresses[addresses_count] = NULL;
memcpy (out_aliases, array_begin (&aliases),
aliases_count * sizeof (char *));
out_aliases[aliases_count] = NULL;
result->h_addr_list = out_addresses;
result->h_aliases = out_aliases;
status = NSS_STATUS_SUCCESS;
}
}
scratch_buffer_free (&tmp_buffer);
array_free (&addresses);
array_free (&aliases);
return status;
}
enum nss_status
_nss_files_gethostbyname3_r (const char *name, int af, struct hostent *result,
char *buffer, size_t buflen, int *errnop,
int *herrnop, int32_t *ttlp, char **canonp)
{
FILE *stream = NULL;
uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct hostent_data);
buffer += pad;
buflen = buflen > pad ? buflen - pad : 0;
/* Open file. */
enum nss_status status = internal_setent (&stream);
if (status == NSS_STATUS_SUCCESS)
{
/* XXX Is using _res to determine whether we want to convert IPv4
addresses to IPv6 addresses really the right thing to do? */
int flags = (res_use_inet6 () ? AI_V4MAPPED : 0);
while ((status = internal_getent (stream, result, buffer, buflen, errnop,
herrnop, af, flags))
== NSS_STATUS_SUCCESS)
{
LOOKUP_NAME_CASE (h_name, h_aliases)
}
if (status == NSS_STATUS_SUCCESS
&& _res_hconf.flags & HCONF_FLAG_MULTI)
status = gethostbyname3_multi
(stream, name, af, result, buffer, buflen, errnop, herrnop, flags);
internal_endent (&stream);
}
if (canonp && status == NSS_STATUS_SUCCESS)
*canonp = result->h_name;
return status;
}
enum nss_status
_nss_files_gethostbyname_r (const char *name, struct hostent *result,
char *buffer, size_t buflen, int *errnop,
int *herrnop)
{
int af = (res_use_inet6 () ? AF_INET6 : AF_INET);
return _nss_files_gethostbyname3_r (name, af, result, buffer, buflen,
errnop, herrnop, NULL, NULL);
}
enum nss_status
_nss_files_gethostbyname2_r (const char *name, int af, struct hostent *result,
char *buffer, size_t buflen, int *errnop,
int *herrnop)
{
return _nss_files_gethostbyname3_r (name, af, result, buffer, buflen,
errnop, herrnop, NULL, NULL);
}
enum nss_status
_nss_files_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
char *buffer, size_t buflen, int *errnop,
int *herrnop, int32_t *ttlp)
{
FILE *stream = NULL;
/* Open file. */
enum nss_status status = internal_setent (&stream);
if (status == NSS_STATUS_SUCCESS)
{
bool any = false;
bool got_canon = false;
while (1)
{
/* Align the buffer for the next record. */
uintptr_t pad = (-(uintptr_t) buffer
% __alignof__ (struct hostent_data));
buffer += pad;
buflen = buflen > pad ? buflen - pad : 0;
struct hostent result;
status = internal_getent (stream, &result, buffer, buflen, errnop,
herrnop, AF_UNSPEC, 0);
if (status != NSS_STATUS_SUCCESS)
break;
int naliases = 0;
if (__strcasecmp (name, result.h_name) != 0)
{
for (; result.h_aliases[naliases] != NULL; ++naliases)
if (! __strcasecmp (name, result.h_aliases[naliases]))
break;
if (result.h_aliases[naliases] == NULL)
continue;
/* We know this alias exist. Count it. */
++naliases;
}
/* Determine how much memory has been used so far. */
// XXX It is not necessary to preserve the aliases array
while (result.h_aliases[naliases] != NULL)
++naliases;
char *bufferend = (char *) &result.h_aliases[naliases + 1];
assert (buflen >= bufferend - buffer);
buflen -= bufferend - buffer;
buffer = bufferend;
/* We found something. */
any = true;
/* Create the record the caller expects. There is only one
address. */
assert (result.h_addr_list[1] == NULL);
if (*pat == NULL)
{
uintptr_t pad = (-(uintptr_t) buffer
% __alignof__ (struct gaih_addrtuple));
buffer += pad;
buflen = buflen > pad ? buflen - pad : 0;
if (__builtin_expect (buflen < sizeof (struct gaih_addrtuple),
0))
{
*errnop = ERANGE;
*herrnop = NETDB_INTERNAL;
status = NSS_STATUS_TRYAGAIN;
break;
}
*pat = (struct gaih_addrtuple *) buffer;
buffer += sizeof (struct gaih_addrtuple);
buflen -= sizeof (struct gaih_addrtuple);
}
(*pat)->next = NULL;
(*pat)->name = got_canon ? NULL : result.h_name;
got_canon = true;
(*pat)->family = result.h_addrtype;
memcpy ((*pat)->addr, result.h_addr_list[0], result.h_length);
(*pat)->scopeid = 0;
pat = &((*pat)->next);
/* If we only look for the first matching entry we are done. */
if ((_res_hconf.flags & HCONF_FLAG_MULTI) == 0)
break;
}
/* If we have to look for multiple records and found one, this
is a success. */
if (status == NSS_STATUS_NOTFOUND && any)
{
assert ((_res_hconf.flags & HCONF_FLAG_MULTI) != 0);
status = NSS_STATUS_SUCCESS;
}
internal_endent (&stream);
}
else if (status == NSS_STATUS_TRYAGAIN)
{
*errnop = errno;
*herrnop = TRY_AGAIN;
}
else
{
*errnop = errno;
*herrnop = NO_DATA;
}
return status;
}