1 /*
2 * Copyright 2017 Timothy Arceri
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 * SOFTWARE.
22 *
23 */
24
25 #include "detect_os.h"
26
27 #if !DETECT_OS_WINDOWS
28 #if defined(HAVE_GETRANDOM)
29 #include <sys/random.h>
30 #endif
31 #include <unistd.h>
32 #include <fcntl.h>
33 #endif
34
35 #include <time.h>
36
37 #include "rand_xor.h"
38
39 /* Super fast random number generator.
40 *
41 * This rand_xorshift128plus function by Sebastiano Vigna belongs
42 * to the public domain.
43 */
44 uint64_t
rand_xorshift128plus(uint64_t seed[2])45 rand_xorshift128plus(uint64_t seed[2])
46 {
47 uint64_t *s = seed;
48
49 uint64_t s1 = s[0];
50 const uint64_t s0 = s[1];
51 s[0] = s0;
52 s1 ^= s1 << 23;
53 s[1] = s1 ^ s0 ^ (s1 >> 18) ^ (s0 >> 5);
54
55 return s[1] + s0;
56 }
57
58 void
s_rand_xorshift128plus(uint64_t seed[2],bool randomised_seed)59 s_rand_xorshift128plus(uint64_t seed[2], bool randomised_seed)
60 {
61 if (!randomised_seed) {
62 /* Use a fixed seed */
63 seed[0] = 0x3bffb83978e24f88;
64 seed[1] = 0x9238d5d56c71cd35;
65 return;
66 }
67
68 #if !DETECT_OS_WINDOWS
69 size_t seed_size = sizeof(uint64_t) * 2;
70
71 #if defined(HAVE_GETRANDOM)
72 ssize_t ret = getrandom(seed, seed_size, GRND_NONBLOCK);
73 if (ret == seed_size)
74 return;
75 #endif
76
77 int fd = open("/dev/urandom", O_RDONLY);
78 if (fd >= 0) {
79 if (read(fd, seed, seed_size) == seed_size) {
80 close(fd);
81 return;
82 }
83 close(fd);
84 }
85 #endif
86
87 seed[0] = 0x3bffb83978e24f88;
88 seed[1] = time(NULL);
89 }
90