blob: 92a86ce78f742f49846a35aec4a5ec1b3bc50c95 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
|
/* 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>
#include "magic.h"
static int magic_initialised = 0;
/*
* magic_init - Initialize the magic number generator.
*
* Attempts to compute a random number seed which will not repeat.
*/
void
magic_init()
{
struct stat statbuf;
long seed = 0;
struct timeval t;
if (magic_initialised)
return;
// 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) {
int nb_read = 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_initialised = 1;
}
/*
* magic - Returns the next magic number.
*/
u_int32_t
magic()
{
if(!magic_initialised)
magic_init();
return (u_int32_t)random();
}
|
