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
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
|
/*
* Random number generator module. Defines a simple API to allocate, use and
* destroy a generator of randomness. Relies on platform-specific APIs.
*/
#include <stdio.h>
#include <stdlib.h>
#include "v_randgen.h"
#if defined _WIN32
/* This is a fall-back to the old style of simply using rand(). It should
* be replaced by something using the proper Win32 cryptography APIs.
* The CryptAcquireContext() and CryptGenRandom() calls sound interesting.
*
* FIXME: Replace ASAP.
*/
VRandGen * v_randgen_new(void)
{
return (VRandGen *) 1; /* Anything that isn't NULL. */
}
void v_randgen_get(VRandGen *gen, void *bytes, size_t num)
{
if(gen != NULL && bytes != NULL)
{
unsigned char *put = bytes, *get;
size_t i;
int x;
while(num > 0)
{
x = rand();
get = (unsigned char *) &x;
for(i = 0; i < sizeof x && num > 0; i++, num--)
*put++ = *get++;
}
}
}
void v_randgen_destroy(VRandGen *gen)
{
/* Nothing to do here. */
}
#else
/* On non-Win32 platforms (which is Linux and Darwin, at the moment), we
* read random data from a file, which is assumed to be one of the kernel's
* virtual files.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
struct VRandGen {
int fd;
};
#define SOURCE "/dev/urandom" /* Name of file to read random bits from. */
VRandGen * v_randgen_new(void)
{
VRandGen *gen;
if((gen = malloc(sizeof *gen)) != NULL)
{
gen->fd = open(SOURCE, O_RDONLY);
if(gen->fd < 0)
{
fprintf(stderr, __FILE__ ": Couldn't open " SOURCE " for reading\n");
free(gen);
gen = NULL;
}
}
return gen;
}
void v_randgen_get(VRandGen *gen, void *bytes, size_t num)
{
if(gen != NULL && bytes != NULL)
{
if(read(gen->fd, bytes, num) != (int) num)
fprintf(stderr, __FILE__ ": Failed to read %u bytes of random data from " SOURCE "\n", (unsigned int) num);
}
}
void v_randgen_destroy(VRandGen *gen)
{
if(gen != NULL)
{
close(gen->fd);
free(gen);
}
}
#endif
|
