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1 | /* |
2 | * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com> | |
3 | * | |
4 | * This file is part of FFmpeg. | |
5 | * | |
6 | * FFmpeg is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU Lesser General Public | |
8 | * License as published by the Free Software Foundation; either | |
9 | * version 2.1 of the License, or (at your option) any later version. | |
10 | * | |
11 | * FFmpeg is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | * Lesser General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU Lesser General Public | |
17 | * License along with FFmpeg; if not, write to the Free Software | |
18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
19 | */ | |
20 | ||
21 | #include "config.h" | |
22 | ||
23 | #if HAVE_UNISTD_H | |
24 | #include <unistd.h> | |
25 | #endif | |
26 | #if HAVE_IO_H | |
27 | #include <io.h> | |
28 | #endif | |
29 | #if HAVE_CRYPTGENRANDOM | |
30 | #include <windows.h> | |
31 | #include <wincrypt.h> | |
32 | #endif | |
33 | #include <fcntl.h> | |
34 | #include <math.h> | |
35 | #include <time.h> | |
36 | #include <string.h> | |
37 | #include "avassert.h" | |
38 | #include "internal.h" | |
39 | #include "intreadwrite.h" | |
40 | #include "timer.h" | |
41 | #include "random_seed.h" | |
42 | #include "sha.h" | |
43 | ||
44 | #ifndef TEST | |
45 | #define TEST 0 | |
46 | #endif | |
47 | ||
48 | static int read_random(uint32_t *dst, const char *file) | |
49 | { | |
50 | #if HAVE_UNISTD_H | |
51 | int fd = avpriv_open(file, O_RDONLY); | |
52 | int err = -1; | |
53 | ||
54 | if (fd == -1) | |
55 | return -1; | |
56 | err = read(fd, dst, sizeof(*dst)); | |
57 | close(fd); | |
58 | ||
59 | return err; | |
60 | #else | |
61 | return -1; | |
62 | #endif | |
63 | } | |
64 | ||
65 | static uint32_t get_generic_seed(void) | |
66 | { | |
67 | uint8_t tmp[120]; | |
68 | struct AVSHA *sha = (void*)tmp; | |
69 | clock_t last_t = 0; | |
70 | static uint64_t i = 0; | |
71 | static uint32_t buffer[512] = { 0 }; | |
72 | unsigned char digest[20]; | |
73 | uint64_t last_i = i; | |
74 | ||
75 | av_assert0(sizeof(tmp) >= av_sha_size); | |
76 | ||
77 | if(TEST){ | |
78 | memset(buffer, 0, sizeof(buffer)); | |
79 | last_i = i = 0; | |
80 | }else{ | |
81 | #ifdef AV_READ_TIME | |
82 | buffer[13] ^= AV_READ_TIME(); | |
83 | buffer[41] ^= AV_READ_TIME()>>32; | |
84 | #endif | |
85 | } | |
86 | ||
87 | for (;;) { | |
88 | clock_t t = clock(); | |
89 | ||
90 | if (last_t == t) { | |
91 | buffer[i & 511]++; | |
92 | } else { | |
93 | buffer[++i & 511] += (t - last_t) % 3294638521U; | |
94 | if (last_i && i - last_i > 4 || i - last_i > 64 || TEST && i - last_i > 8) | |
95 | break; | |
96 | } | |
97 | last_t = t; | |
98 | } | |
99 | ||
100 | if(TEST) | |
101 | buffer[0] = buffer[1] = 0; | |
102 | ||
103 | av_sha_init(sha, 160); | |
104 | av_sha_update(sha, (const uint8_t *)buffer, sizeof(buffer)); | |
105 | av_sha_final(sha, digest); | |
106 | return AV_RB32(digest) + AV_RB32(digest + 16); | |
107 | } | |
108 | ||
109 | uint32_t av_get_random_seed(void) | |
110 | { | |
111 | uint32_t seed; | |
112 | ||
113 | #if HAVE_CRYPTGENRANDOM | |
114 | HCRYPTPROV provider; | |
115 | if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL, | |
116 | CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) { | |
117 | BOOL ret = CryptGenRandom(provider, sizeof(seed), (PBYTE) &seed); | |
118 | CryptReleaseContext(provider, 0); | |
119 | if (ret) | |
120 | return seed; | |
121 | } | |
122 | #endif | |
123 | ||
124 | if (read_random(&seed, "/dev/urandom") == sizeof(seed)) | |
125 | return seed; | |
126 | if (read_random(&seed, "/dev/random") == sizeof(seed)) | |
127 | return seed; | |
128 | return get_generic_seed(); | |
129 | } | |
130 | ||
131 | #if TEST | |
132 | #undef printf | |
133 | #define N 256 | |
134 | #include <stdio.h> | |
135 | ||
136 | int main(void) | |
137 | { | |
138 | int i, j, retry; | |
139 | uint32_t seeds[N]; | |
140 | ||
141 | for (retry=0; retry<3; retry++){ | |
142 | for (i=0; i<N; i++){ | |
143 | seeds[i] = av_get_random_seed(); | |
144 | for (j=0; j<i; j++) | |
145 | if (seeds[j] == seeds[i]) | |
146 | goto retry; | |
147 | } | |
148 | printf("seeds OK\n"); | |
149 | return 0; | |
150 | retry:; | |
151 | } | |
152 | printf("FAIL at %d with %X\n", j, seeds[j]); | |
153 | return 1; | |
154 | } | |
155 | #endif |