magic.c

来自「PPPoE协议在Psos中的实现源代码」· C语言 代码 · 共 53 行

/************************************************************************/
/*
 * magic.c - PPP Magic Number routines.
 *
 * Copyright (c) 1989 Carnegie Mellon University.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Carnegie Mellon University.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <stdlib.h>

#include "ppptypes.h"
#include "magic.h"

static u_long  next;      /* Next value to return */


/*
 * magic_init - Initialize the magic number generator.
 *
 * Computes first magic number and seed for random number generator.
 * Attempts to compute a random number seed which will not repeat.
 * The current method relies on user configured IP address.
 */
void magic_init(void)
{
    srand((unsigned int) &next); /*Use an address in our space. JRC*/
    next = rand();
}


/*
 * magic - Returns the next magic number.
 */
u_int32_t  magic(void)
{
    u_long m = next;

    next = (u_long) rand();
    return ((u_int32_t) m);
}