/* * 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 <unistd.h>#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <sys/time.h>#include "magic.h"#ifndef linuxstatic u_int32_t next;		/* Next value to return */#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 = 0;	/* /dev/urandom */#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. */voidmagic_init(){    long seed;    struct timeval t;#ifdef linux	rfd = open("/dev/urandom", O_RDONLY);	if(rfd != -1) 			return;	else {		rfd = 0;#endif	/* if /dev/urandom fails, we try traditional method */    gettimeofday(&t, NULL);    seed = gethostid() ^ t.tv_sec ^ t.tv_usec ^ getpid();    srand48(seed);#ifdef linux	}#endif}/* * magic - Returns the next magic number. */u_int32_tmagic(){#ifdef linux	u_int32_t ret = 0;	if(rfd) 	{		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. */doubledrand48(){    return (double)random() / (double)0x7fffffffL; /* 2**31-1 */}longmrand48(){    return random();}voidsrand48(seedval)long seedval;{    srandom((int)seedval);}#endif