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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>
#include <sys/stat.h>
#include <fcntl.h>
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "magic.h"
#ifdef _MSC_VER
# pragma section(".CRT$XCU",read)
# define INITIALIZER2_(f,p) \
static void f(void); \
__declspec(allocate(".CRT$XCU")) void (*f##_)(void) = f; \
__pragma(comment(linker,"/include:" p #f "_")) \
static void f(void)
# ifdef _WIN64
# define INITIALIZER(f) INITIALIZER2_(f,"")
# else
# define INITIALIZER(f) INITIALIZER2_(f,"_")
# endif
#else /* __GNUC__ */
# define INITIALIZER(f) \
static void f(void) __attribute__((constructor)); \
static void f(void)
#endif
/* if OpenSSL library is available this legacy code will not be compiled in */
#if defined(HAVE_OPENSSL_RAND_H) && defined(HAVE_LIBCRYPTO)
#include <openssl/rand.h>
/*
* magic - Returns the next magic number.
*/
u_int32_t
magic()
{
u_int32_t num;
RAND_pseudo_bytes((unsigned char *)&num, sizeof(num));
return num;
}
#elif defined(HAVE_GETRANDOM)
# if defined(HAVE_LINUX_RANDOM_H)
# include <linux/random.h>
# elif defined(HAVE_SYS_RANDOM_H)
# include <sys/random.h>
# endif
/*
* magic - Returns the next magic number.
*/
u_int32_t
magic()
{
u_int32_t num;
getrandom(&num, sizeof(num), GRND_NONBLOCK);
return num;
}
#else
/*
* magic_init - Initialize the magic number generator.
*
* Attempts to compute a random number seed which will not repeat.
*/
INITIALIZER(magic_init)
{
struct stat statbuf;
long seed = 0;
struct timeval t;
// try to initialise seed from urandom
if (!lstat("/dev/urandom", &statbuf) && S_ISCHR(statbuf.st_mode)) {
int rfd = open("/dev/urandom", O_RDONLY);
if(rfd >= 0) {
(void) read(rfd, &seed, sizeof(seed));
close(rfd);
}
}
// fallback
gettimeofday(&t, NULL);
seed ^= gethostid() ^ t.tv_sec ^ t.tv_usec ^ getpid();
// finally seed the PRNG
srandom(seed);
}
/*
* magic - Returns the next magic number.
*/
u_int32_t
magic()
{
return (u_int32_t)random();
}
#endif
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