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/* random.c - random number generator
* Copyright (c) 1997 by Werner Koch (dd9jn)
*
* This file is part of G10.
*
* G10 is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* G10 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "util.h"
#include "cipher.h"
struct cache {
int len;
byte buffer[100]; /* fixme: should be allocalted with m_alloc_secure()*/
};
static struct cache cache[3];
#define MASK_LEVEL(a) do {if( a > 2 ) a = 2; else if( a < 0 ) a = 0; } while(0)
static int open_device( const char *name, int minor );
static void fill_buffer( byte *buffer, size_t length, int level );
/****************
* Fill the buffer with LENGTH bytes of cryptologic strong
* random bytes. level 0 is not very strong, 1 is strong enough
* for most usage, 2 is good for key generation stuff but may be very slow.
*/
void
randomize_buffer( byte *buffer, size_t length, int level )
{
for( ; length; length-- )
*buffer++ = get_random_byte(level);
}
byte
get_random_byte( int level )
{
MASK_LEVEL(level);
if( !cache[level].len ) {
fill_buffer(cache[level].buffer, DIM(cache[level].buffer), level );
cache[level].len = DIM(cache[level].buffer);
}
return cache[level].buffer[--cache[level].len];
}
static int
open_device( const char *name, int minor )
{
int fd;
struct stat sb;
fd = open( name, O_RDONLY );
if( fd == -1 )
log_fatal("can't open %s: %s\n", name, strerror(errno) );
if( fstat( fd, &sb ) )
log_fatal("stat() off %s failed: %s\n", name, strerror(errno) );
if( !S_ISCHR(sb.st_mode)
#ifdef __linux__
|| (sb.st_rdev >> 8) != 1
|| (sb.st_rdev & 0xff) != minor
#endif
)
log_fatal("invalid random device!\n" );
return fd;
}
static void
fill_buffer( byte *buffer, size_t length, int level )
{
FILE *fp;
static int fd_urandom = -1;
static int fd_random = -1;
int fd;
int n;
if( level == 2 ) {
if( fd_random == -1 )
fd_random = open_device( "/dev/random", 8 );
fd = fd_random;
}
else {
if( fd_urandom == -1 )
fd_urandom = open_device( "/dev/urandom", 9 );
fd = fd_urandom;
}
do {
do {
n = read(fd, buffer, length );
} while( n == -1 && errno == EINTR );
if( n == -1 )
log_fatal("read error on random device: %s\n", strerror(errno) );
buffer += n;
length -= n;
} while( length );
}
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