glibc/nss/nss_files/files-hosts.c

483 lines
14 KiB
C

/* Hosts file parser in nss_files module.
Copyright (C) 1996-2016 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.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.options & RES_USE_INET6) ? AF_INET6 : AF_INET), \
((_res.options & 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
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.options & 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)
{
/* We have to get all host entries from the file. */
size_t tmp_buflen = MIN (buflen, 4096);
char tmp_buffer_stack[tmp_buflen]
__attribute__ ((__aligned__ (__alignof__ (struct hostent_data))));
char *tmp_buffer = tmp_buffer_stack;
struct hostent tmp_result_buf;
int naddrs = 1;
int naliases = 0;
char *bufferend;
bool tmp_buffer_malloced = false;
while (result->h_aliases[naliases] != NULL)
++naliases;
bufferend = (char *) &result->h_aliases[naliases + 1];
again:
while ((status = internal_getent (stream, &tmp_result_buf, tmp_buffer,
tmp_buflen, errnop, herrnop, af,
flags))
== NSS_STATUS_SUCCESS)
{
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 (matches)
{
/* We could be very clever and try to recycle a few bytes
in the buffer instead of generating new arrays. But
we are not doing this here since it's more work than
it's worth. Simply let the user provide a bit bigger
buffer. */
char **new_h_addr_list;
char **new_h_aliases;
int newaliases = 0;
size_t newstrlen = 0;
int cnt;
/* Count the new aliases and the length of the strings. */
while (tmp_result_buf.h_aliases[newaliases] != NULL)
{
char *cp = tmp_result_buf.h_aliases[newaliases];
++newaliases;
newstrlen += strlen (cp) + 1;
}
/* 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. */
if (strcmp (old_result->h_name,
tmp_result_buf.h_name) != 0)
{
++newaliases;
newstrlen += strlen (tmp_result_buf.h_name) + 1;
}
/* Make sure bufferend is aligned. */
assert ((bufferend - (char *) 0) % sizeof (char *) == 0);
/* Now we can check whether the buffer is large enough.
16 is the maximal size of the IP address. */
if (bufferend + 16 + (naddrs + 2) * sizeof (char *)
+ roundup (newstrlen, sizeof (char *))
+ (naliases + newaliases + 1) * sizeof (char *)
>= buffer + buflen)
{
*errnop = ERANGE;
*herrnop = NETDB_INTERNAL;
status = NSS_STATUS_TRYAGAIN;
goto out;
}
new_h_addr_list =
(char **) (bufferend
+ roundup (newstrlen, sizeof (char *))
+ 16);
new_h_aliases =
(char **) ((char *) new_h_addr_list
+ (naddrs + 2) * sizeof (char *));
/* Copy the old data in the new arrays. */
for (cnt = 0; cnt < naddrs; ++cnt)
new_h_addr_list[cnt] = old_result->h_addr_list[cnt];
for (cnt = 0; cnt < naliases; ++cnt)
new_h_aliases[cnt] = old_result->h_aliases[cnt];
/* Store the new strings. */
cnt = 0;
while (tmp_result_buf.h_aliases[cnt] != NULL)
{
new_h_aliases[naliases++] = bufferend;
bufferend = (__stpcpy (bufferend,
tmp_result_buf.h_aliases[cnt])
+ 1);
++cnt;
}
if (cnt < newaliases)
{
new_h_aliases[naliases++] = bufferend;
bufferend = __stpcpy (bufferend,
tmp_result_buf.h_name) + 1;
}
/* Final NULL pointer. */
new_h_aliases[naliases] = NULL;
/* Round up the buffer end address. */
bufferend += (sizeof (char *)
- ((bufferend - (char *) 0)
% sizeof (char *))) % sizeof (char *);
/* Now the new address. */
new_h_addr_list[naddrs++] =
memcpy (bufferend, tmp_result_buf.h_addr,
tmp_result_buf.h_length);
/* Also here a final NULL pointer. */
new_h_addr_list[naddrs] = NULL;
/* Store the new array pointers. */
old_result->h_aliases = new_h_aliases;
old_result->h_addr_list = new_h_addr_list;
/* Compute the new buffer end. */
bufferend = (char *) &new_h_aliases[naliases + 1];
assert (bufferend <= buffer + buflen);
result = old_result;
}
}
if (status == NSS_STATUS_TRYAGAIN)
{
size_t newsize = 2 * tmp_buflen;
if (tmp_buffer_malloced)
{
char *newp = realloc (tmp_buffer, newsize);
if (newp != NULL)
{
assert ((((uintptr_t) newp)
& (__alignof__ (struct hostent_data) - 1))
== 0);
tmp_buffer = newp;
tmp_buflen = newsize;
goto again;
}
}
else if (!__libc_use_alloca (buflen + newsize))
{
tmp_buffer = malloc (newsize);
if (tmp_buffer != NULL)
{
assert ((((uintptr_t) tmp_buffer)
& (__alignof__ (struct hostent_data) - 1))
== 0);
tmp_buffer_malloced = true;
tmp_buflen = newsize;
goto again;
}
}
else
{
tmp_buffer
= extend_alloca (tmp_buffer, tmp_buflen,
newsize
+ __alignof__ (struct hostent_data));
tmp_buffer = (char *) (((uintptr_t) tmp_buffer
+ __alignof__ (struct hostent_data)
- 1)
& ~(__alignof__ (struct hostent_data)
- 1));
goto again;
}
}
else
status = NSS_STATUS_SUCCESS;
out:
if (tmp_buffer_malloced)
free (tmp_buffer);
}
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.options & 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;
}