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
|
/*
* This file is part of PowerDNS or dnsdist.
* Copyright -- PowerDNS.COM B.V. and its contributors
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* In addition, for the avoidance of any doubt, permission is granted to
* link this program with OpenSSL and to (re)distribute the binaries
* produced as the result of such linking.
*
* 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; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include <stdexcept>
#include <sys/time.h>
#include <unistd.h>
#ifdef HAVE_LIBSODIUM
#include <sodium.h>
#endif /* HAVE_LIBSODIUM */
#ifdef HAVE_RAND_BYTES
#include <openssl/rand.h>
#endif /* HAVE_RAND_BYTES */
#if defined(HAVE_GETRANDOM)
#include <sys/random.h>
#endif
#include "dnsdist-random.hh"
#include "dns_random.hh"
#include "dolog.hh"
#include "misc.hh"
namespace dnsdist
{
#if !defined(HAVE_LIBSODIUM) && defined(HAVE_GETRANDOM)
static bool s_useGetRandom{true};
#endif
void initRandom()
{
#ifdef HAVE_LIBSODIUM
srandom(randombytes_random());
#else
{
auto getSeed = []() {
#if defined(HAVE_GETRANDOM)
char buf[1];
// some systems define getrandom but it does not really work, e.g. because it's
// not present in kernel.
if (getrandom(buf, sizeof(buf), 0) == -1 && errno != EINTR) {
warnlog("getrandom() failed %s", stringerror());
s_useGetRandom = false;
}
#endif /* HAVE_GETRANDOM */
#ifdef HAVE_RAND_BYTES
unsigned int seed;
if (RAND_bytes(reinterpret_cast<unsigned char*>(&seed), sizeof(seed)) == 1) {
return seed;
}
#endif /* HAVE_RAND_BYTES */
struct timeval tv;
gettimeofday(&tv, 0);
return static_cast<unsigned int>(tv.tv_sec ^ tv.tv_usec ^ getpid());
};
srandom(getSeed());
}
#endif
}
uint32_t getRandomValue(uint32_t upperBound)
{
#ifdef HAVE_LIBSODIUM
return randombytes_uniform(upperBound);
#else /* HAVE_LIBSODIUM */
uint32_t result = 0;
unsigned int min = pdns::random_minimum_acceptable_value(upperBound);
#if defined(HAVE_GETRANDOM)
if (s_useGetRandom) {
do {
auto got = getrandom(&result, sizeof(result), 0);
if (got == -1 && errno == EINTR) {
continue;
}
if (got != sizeof(result)) {
throw std::runtime_error("Error getting a random value via getrandom(): " + stringerror());
}
} while (result < min);
return result % upperBound;
}
#endif /* HAVE_GETRANDOM */
#ifdef HAVE_RAND_BYTES
do {
if (RAND_bytes(reinterpret_cast<unsigned char*>(&result), sizeof(result)) != 1) {
throw std::runtime_error("Error getting a random value via RAND_bytes");
}
} while (result < min);
return result % upperBound;
#endif /* HAVE_RAND_BYTES */
do {
result = random();
} while (result < min);
return result % upperBound;
#endif /* HAVE_LIBSODIUM */
}
uint16_t getRandomDNSID()
{
return getRandomValue(65536);
}
}
|
