blob: d1c9a3f7046d7efada2e11194819e113ab0f6bb7
| 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 | uint64_t tmp[120/8]; |
| 68 | struct AVSHA *sha = (void*)tmp; |
| 69 | clock_t last_t = 0; |
| 70 | clock_t last_td = 0; |
| 71 | clock_t init_t = 0; |
| 72 | static uint64_t i = 0; |
| 73 | static uint32_t buffer[512] = { 0 }; |
| 74 | unsigned char digest[20]; |
| 75 | uint64_t last_i = i; |
| 76 | |
| 77 | av_assert0(sizeof(tmp) >= av_sha_size); |
| 78 | |
| 79 | if(TEST){ |
| 80 | memset(buffer, 0, sizeof(buffer)); |
| 81 | last_i = i = 0; |
| 82 | }else{ |
| 83 | #ifdef AV_READ_TIME |
| 84 | buffer[13] ^= AV_READ_TIME(); |
| 85 | buffer[41] ^= AV_READ_TIME()>>32; |
| 86 | #endif |
| 87 | } |
| 88 | |
| 89 | for (;;) { |
| 90 | clock_t t = clock(); |
| 91 | if (last_t + 2*last_td + (CLOCKS_PER_SEC > 1000) >= t) { |
| 92 | last_td = t - last_t; |
| 93 | buffer[i & 511] = 1664525*buffer[i & 511] + 1013904223 + (last_td % 3294638521U); |
| 94 | } else { |
| 95 | last_td = t - last_t; |
| 96 | buffer[++i & 511] += last_td % 3294638521U; |
| 97 | if ((t - init_t) >= CLOCKS_PER_SEC>>5) |
| 98 | if (last_i && i - last_i > 4 || i - last_i > 64 || TEST && i - last_i > 8) |
| 99 | break; |
| 100 | } |
| 101 | last_t = t; |
| 102 | if (!init_t) |
| 103 | init_t = t; |
| 104 | } |
| 105 | |
| 106 | if(TEST) { |
| 107 | buffer[0] = buffer[1] = 0; |
| 108 | } else { |
| 109 | #ifdef AV_READ_TIME |
| 110 | buffer[111] += AV_READ_TIME(); |
| 111 | #endif |
| 112 | } |
| 113 | |
| 114 | av_sha_init(sha, 160); |
| 115 | av_sha_update(sha, (const uint8_t *)buffer, sizeof(buffer)); |
| 116 | av_sha_final(sha, digest); |
| 117 | return AV_RB32(digest) + AV_RB32(digest + 16); |
| 118 | } |
| 119 | |
| 120 | uint32_t av_get_random_seed(void) |
| 121 | { |
| 122 | uint32_t seed; |
| 123 | |
| 124 | #if HAVE_CRYPTGENRANDOM |
| 125 | HCRYPTPROV provider; |
| 126 | if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL, |
| 127 | CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) { |
| 128 | BOOL ret = CryptGenRandom(provider, sizeof(seed), (PBYTE) &seed); |
| 129 | CryptReleaseContext(provider, 0); |
| 130 | if (ret) |
| 131 | return seed; |
| 132 | } |
| 133 | #endif |
| 134 | |
| 135 | #if HAVE_ARC4RANDOM |
| 136 | return arc4random(); |
| 137 | #endif |
| 138 | |
| 139 | if (read_random(&seed, "/dev/urandom") == sizeof(seed)) |
| 140 | return seed; |
| 141 | if (read_random(&seed, "/dev/random") == sizeof(seed)) |
| 142 | return seed; |
| 143 | return get_generic_seed(); |
| 144 | } |
| 145 |