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/* rndlinux.c - raw random number for OSes with /dev/random
* Copyright (C) 1998, 2001, 2002, 2003 Free Software Foundation, Inc.
*
* This file is part of Libgcrypt.
*
* Libgcrypt 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.
*
* Libgcrypt 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 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/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifdef HAVE_GETTIMEOFDAY
# include <sys/times.h>
#endif
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include "types.h"
#include "g10lib.h"
#include "rand-internal.h"
static int open_device ( const char *name );
int _gcry_rndlinux_gather_random (void (*add)(const void*, size_t, int),
int requester,
size_t length, int level );
static int
set_cloexec_flag (int fd)
{
int oldflags;
oldflags= fcntl (fd, F_GETFD, 0);
if (oldflags < 0)
return oldflags;
oldflags |= FD_CLOEXEC;
return fcntl (fd, F_SETFD, oldflags);
}
/*
* Used to open the /dev/random devices (Linux, xBSD, Solaris (if it exists)).
*/
static int
open_device ( const char *name )
{
int fd;
fd = open ( name, O_RDONLY );
if ( fd == -1 )
log_fatal ("can't open %s: %s\n", name, strerror(errno) );
if (set_cloexec_flag (fd))
log_error ("error setting FD_CLOEXEC on fd %d: %s\n",
fd, strerror (errno));
/* We used to do the following check, however it turned out that this
is not portable since more OSes provide a random device which is
sometimes implemented as another device type.
struct stat sb;
if( fstat( fd, &sb ) )
log_fatal("stat() off %s failed: %s\n", name, strerror(errno) );
if( (!S_ISCHR(sb.st_mode)) && (!S_ISFIFO(sb.st_mode)) )
log_fatal("invalid random device!\n" );
*/
return fd;
}
int
_gcry_rndlinux_gather_random (void (*add)(const void*, size_t, int),
int requester,
size_t length, int level )
{
static int fd_urandom = -1;
static int fd_random = -1;
int fd;
int n;
int warn=0;
byte buffer[768];
if( level >= 2 )
{
if( fd_random == -1 )
fd_random = open_device ( NAME_OF_DEV_RANDOM );
fd = fd_random;
}
else
{
if( fd_urandom == -1 )
fd_urandom = open_device ( NAME_OF_DEV_URANDOM );
fd = fd_urandom;
}
while (length)
{
fd_set rfds;
struct timeval tv;
int rc;
FD_ZERO(&rfds);
FD_SET(fd, &rfds);
tv.tv_sec = 3;
tv.tv_usec = 0;
if( !(rc=select(fd+1, &rfds, NULL, NULL, &tv)) )
{
if( !warn )
{
_gcry_random_progress ("need_entropy", 'X', 0, (int)length);
warn = 1;
}
continue;
}
else if( rc == -1 )
{
log_error ("select() error: %s\n", strerror(errno));
continue;
}
do
{
int nbytes = length < sizeof(buffer)? length : sizeof(buffer);
n = read(fd, buffer, nbytes );
if( n >= 0 && n > nbytes )
{
log_error("bogus read from random device (n=%d)\n", n );
n = nbytes;
}
}
while( n == -1 && errno == EINTR );
if( n == -1 )
log_fatal("read error on random device: %s\n", strerror(errno));
(*add)( buffer, n, requester );
length -= n;
}
memset(buffer, 0, sizeof(buffer) );
return 0; /* success */
}
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