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/* magic.c - PPP Magic Number routines.
*
* Copyright (C) 1989 Carnegie Mellon University.
*
* This program 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.
*
* This program 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 - see the file COPYING.
*
* See `CHANGES' file for revision history.
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/time.h>
#include <unistd.h>
/* u_int32_t support for sun */
#ifdef sun
typedef unsigned int u_int32_t;
#endif
#include "magic.h"
#ifndef __linux__
extern long mrand48 __P((void));
extern void srand48 __P((long));
#else
#include <sys/stat.h>
#include <fcntl.h>
/* on Linux we use /dev/urandom as random numbers source
I find it really cool :) */
int rfd = -1; /* /dev/urandom */
int magic_inited = 0;
#endif
/*
* magic_init - Initialize the magic number generator.
*
* Attempts to compute a random number seed which will not repeat.
* The current method uses the current hostid, current process ID
* and current time, currently.
*/
void
magic_init()
{
long seed;
struct timeval t;
#ifdef __linux__
magic_inited = 1;
rfd = open("/dev/urandom", O_RDONLY);
if(rfd != -1)
return;
#endif
/* if /dev/urandom fails, we try traditional method */
gettimeofday(&t, NULL);
seed = gethostid() ^ t.tv_sec ^ t.tv_usec ^ getpid();
srand48(seed);
}
/*
* magic - Returns the next magic number.
*/
u_int32_t
magic()
{
#ifdef __linux__
u_int32_t ret = 0;
if (magic_inited == 0 )
magic_init();
if(rfd > -1) {
read(rfd, &ret, sizeof(ret));
return ret;
}
else
return (u_int32_t) mrand48();
#else
return (u_int32_t) mrand48();
#endif
}
#ifdef NO_DRAND48
/*
* Substitute procedures for those systems which don't have
* drand48 et al.
*/
double
drand48()
{
return (double)random() / (double)0x7fffffffL; /* 2**31-1 */
}
long
mrand48()
{
return random();
}
void
srand48(seedval)
long seedval;
{
srandom((int)seedval);
}
#endif
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