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
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
/*************************************************
* Device EntropySource Source File *
* (C) 1999-2008 Jack Lloyd *
*************************************************/
#include <botan/es_dev.h>
#include <sys/select.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/fcntl.h>
#include <unistd.h>
namespace Botan {
/**
Close the device, if open
*/
void Device_EntropySource::Device_Reader::close()
{
if(fd > 0) { ::close(fd); fd = -1; }
}
/**
Read bytes from a device file
*/
u32bit Device_EntropySource::Device_Reader::get(byte out[], u32bit length,
u32bit ms_wait_time)
{
if(fd < 0)
return 0;
if(fd >= FD_SETSIZE)
return 0;
fd_set read_set;
FD_ZERO(&read_set);
FD_SET(fd, &read_set);
struct ::timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec = ms_wait_time * 1000;
if(::select(fd + 1, &read_set, 0, 0, &timeout) < 0)
return 0;
if(!(FD_ISSET(fd, &read_set)))
return 0;
const ssize_t got = ::read(fd, out, length);
if(got <= 0)
return 0;
const u32bit ret = static_cast<u32bit>(got);
if(ret > length)
return 0;
return ret;
}
/**
Attempt to open a device
*/
Device_EntropySource::Device_Reader::fd_type
Device_EntropySource::Device_Reader::open(const std::string& pathname)
{
#ifndef O_NONBLOCK
#define O_NONBLOCK 0
#endif
#ifndef O_NOCTTY
#define O_NOCTTY 0
#endif
const int flags = O_RDONLY | O_NONBLOCK | O_NOCTTY;
return ::open(pathname.c_str(), flags);
}
/**
Device_EntropySource constructor
*/
Device_EntropySource::Device_EntropySource(
const std::vector<std::string>& fsnames)
{
for(u32bit i = 0; i != fsnames.size(); ++i)
{
Device_Reader::fd_type fd = Device_Reader::open(fsnames[i]);
if(fd > 0)
devices.push_back(Device_Reader(fd));
}
}
/**
* Gather entropy from a RNG device
*/
u32bit Device_EntropySource::slow_poll(byte output[], u32bit length)
{
for(size_t i = 0; i != devices.size(); ++i)
{
const u32bit got = devices[i].get(output, length, 100);
if(got)
return got;
}
return 0;
}
/**
* Fast poll: try limit to 10 ms wait
*/
u32bit Device_EntropySource::fast_poll(byte output[], u32bit length)
{
for(size_t i = 0; i != devices.size(); ++i)
{
const u32bit got = devices[i].get(output, length, 10);
if(got)
return got;
}
return 0;
}
Device_EntropySource::~Device_EntropySource()
{
for(size_t i = 0; i != devices.size(); ++i)
devices[i].close();
}
}
|
