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/* Common code for DB-based databases in nss_db module.
Copyright (C) 1996-2020 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 <dlfcn.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdint.h>
#include <sys/mman.h>
#include <libc-lock.h>
#include "nsswitch.h"
#include "nss_db.h"
/* The hashing function we use. */
#include "../intl/hash-string.h"
/* These symbols are defined by the including source file:
ENTNAME -- database name of the structure and functions (hostent, pwent).
STRUCTURE -- struct name, define only if not ENTNAME (passwd, group).
DATABASE -- database file name, ("hosts", "passwd")
NEED_H_ERRNO - defined iff an arg `int *herrnop' is used.
*/
#define ENTNAME_r CONCAT(ENTNAME,_r)
#include <paths.h>
#define DBFILE _PATH_VARDB DATABASE ".db"
#ifdef NEED_H_ERRNO
# define H_ERRNO_PROTO , int *herrnop
# define H_ERRNO_ARG , herrnop
# define H_ERRNO_SET(val) (*herrnop = (val))
#else
# define H_ERRNO_PROTO
# define H_ERRNO_ARG
# define H_ERRNO_SET(val) ((void) 0)
#endif
/* State for this database. */
static struct nss_db_map state;
/* Lock to protect the state and global variables. */
__libc_lock_define (static , lock);
/* Maintenance of the shared handle open on the database. */
static int keep_db;
static const char *entidx;
/* Open the database. */
enum nss_status
CONCAT(_nss_db_set,ENTNAME) (int stayopen)
{
enum nss_status status;
__libc_lock_lock (lock);
status = internal_setent (DBFILE, &state);
if (status == NSS_STATUS_SUCCESS)
{
/* Remember STAYOPEN flag. */
keep_db |= stayopen;
/* Reset the sequential index. */
entidx = NULL;
}
__libc_lock_unlock (lock);
return status;
}
/* Close it again. */
enum nss_status
CONCAT(_nss_db_end,ENTNAME) (void)
{
__libc_lock_lock (lock);
internal_endent (&state);
/* Reset STAYOPEN flag. */
keep_db = 0;
__libc_lock_unlock (lock);
return NSS_STATUS_SUCCESS;
}
/* Macro for defining lookup functions for this DB-based database.
NAME is the name of the lookup; e.g. `pwnam'.
DB_CHAR is index indicator for the database.
KEYPATTERN gives `printf' args to construct a key string;
e.g. `("%d", id)'.
KEYSIZE gives the allocation size of a buffer to construct it in;
e.g. `1 + sizeof (id) * 4'.
PROTO is the potentially empty list of other parameters.
BREAK_IF_MATCH is a block of code which compares `struct STRUCTURE *result'
to the lookup key arguments and does `break;' if they match. */
#define DB_LOOKUP(name, db_char, keysize, keypattern, break_if_match, proto...)\
enum nss_status \
_nss_db_get##name##_r (proto, struct STRUCTURE *result, \
char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO)\
{ \
struct parser_data *data = (void *) buffer; \
\
if (buflen < sizeof *data) \
{ \
*errnop = ERANGE; \
H_ERRNO_SET (NETDB_INTERNAL); \
return NSS_STATUS_TRYAGAIN; \
} \
\
struct nss_db_map state = { NULL, 0 }; \
enum nss_status status = internal_setent (DBFILE, &state); \
if (status != NSS_STATUS_SUCCESS) \
{ \
*errnop = errno; \
H_ERRNO_SET (NETDB_INTERNAL); \
return status; \
} \
\
const struct nss_db_header *header = state.header; \
int i; \
for (i = 0; i < header->ndbs; ++i) \
if (header->dbs[i].id == db_char) \
break; \
if (i == header->ndbs) \
{ \
status = NSS_STATUS_UNAVAIL; \
goto out; \
} \
\
char *key; \
if (db_char == '.') \
key = (char *) IGNOREPATTERN keypattern; \
else \
{ \
const size_t size = (keysize) + 1; \
key = alloca (size); \
\
KEYPRINTF keypattern; \
} \
\
const stridx_t *hashtable \
= (const stridx_t *) ((const char *) header \
+ header->dbs[i].hashoffset); \
const char *valstrtab = (const char *) header + header->valstroffset; \
uint32_t hashval = __hash_string (key); \
size_t hidx = hashval % header->dbs[i].hashsize; \
size_t hval2 = 1 + hashval % (header->dbs[i].hashsize - 2); \
\
status = NSS_STATUS_NOTFOUND; \
while (hashtable[hidx] != ~((stridx_t) 0)) \
{ \
const char *valstr = valstrtab + hashtable[hidx]; \
size_t len = strlen (valstr) + 1; \
if (len > buflen) \
{ \
/* No room to copy the data to. */ \
*errnop = ERANGE; \
H_ERRNO_SET (NETDB_INTERNAL); \
status = NSS_STATUS_TRYAGAIN; \
break; \
} \
\
/* Copy the string to a place where it can be modified. */ \
char *p = memcpy (buffer, valstr, len); \
\
int err = parse_line (p, result, data, buflen, errnop EXTRA_ARGS); \
\
/* Advance before break_if_match, lest it uses continue to skip
to the next entry. */ \
if ((hidx += hval2) >= header->dbs[i].hashsize) \
hidx -= header->dbs[i].hashsize; \
\
if (err > 0) \
{ \
status = NSS_STATUS_SUCCESS; \
break_if_match; \
status = NSS_STATUS_NOTFOUND; \
} \
else if (err == -1) \
{ \
H_ERRNO_SET (NETDB_INTERNAL); \
status = NSS_STATUS_TRYAGAIN; \
break; \
} \
} \
\
if (status == NSS_STATUS_NOTFOUND) \
H_ERRNO_SET (HOST_NOT_FOUND); \
\
out: \
internal_endent (&state); \
\
return status; \
}
#define KEYPRINTF(pattern, args...) snprintf (key, size, pattern ,##args)
#define IGNOREPATTERN(pattern, arg1, args...) (char *) (uintptr_t) arg1
/* Return the next entry from the database file, doing locking. */
enum nss_status
CONCAT(_nss_db_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
size_t buflen, int *errnop H_ERRNO_PROTO)
{
/* Return next entry in host file. */
enum nss_status status;
struct parser_data *data = (void *) buffer;
if (buflen < sizeof *data)
{
*errnop = ERANGE;
H_ERRNO_SET (NETDB_INTERNAL);
return NSS_STATUS_TRYAGAIN;
}
__libc_lock_lock (lock);
if (state.header == NULL)
{
status = internal_setent (DBFILE, &state);
if (status != NSS_STATUS_SUCCESS)
{
*errnop = errno;
H_ERRNO_SET (NETDB_INTERNAL);
goto out;
}
entidx = NULL;
}
/* Start from the beginning if freshly initialized or reset
requested by set*ent. */
if (entidx == NULL)
entidx = (const char *) state.header + state.header->valstroffset;
status = NSS_STATUS_UNAVAIL;
if (state.header != MAP_FAILED)
{
const char *const end = ((const char *) state.header
+ state.header->valstroffset
+ state.header->valstrlen);
while (entidx < end)
{
const char *next = rawmemchr (entidx, '\0') + 1;
size_t len = next - entidx;
if (len > buflen)
{
/* No room to copy the data to. */
*errnop = ERANGE;
H_ERRNO_SET (NETDB_INTERNAL);
status = NSS_STATUS_TRYAGAIN;
break;
}
/* Copy the string to a place where it can be modified. */
char *p = memcpy (buffer, entidx, len);
int err = parse_line (p, result, data, buflen, errnop EXTRA_ARGS);
if (err > 0)
{
status = NSS_STATUS_SUCCESS;
entidx = next;
break;
}
if (err < 0)
{
H_ERRNO_SET (NETDB_INTERNAL);
status = NSS_STATUS_TRYAGAIN;
break;
}
/* Continue with the next record, this one is ill-formed. */
entidx = next;
}
}
out:
__libc_lock_unlock (lock);
return status;
}
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