File: arc4random.c

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/*	$KAME: arc4random.c,v 1.1 2003/01/22 01:30:36 jinmei Exp $	*/

/*
 * Copyright (C) 2000 WIDE Project.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the project nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
/*
 * a stub function to make random() to return good random numbers.
 */

#include <sys/types.h>
#include <sys/param.h>
#include <sys/uio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <err.h>

#include "arc4random.h"

static int fd = -1;

static void
arc4random_init()
{

	fd = open("/dev/urandom", O_RDONLY, 0600);
	if (fd < 0) {
		err(1, "/dev/urandom");
		/*NOTREACHED*/
	}
}

u_int32_t
arc4random()
{
	u_int32_t v;
	ssize_t n;

	if (fd < 0)
		arc4random_init();
	n = read(fd, &v, sizeof(v));
	return v;
}