random_seed.c (4265B)
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_BCRYPT 30 #include <windows.h> 31 #include <bcrypt.h> 32 #endif 33 #if CONFIG_GCRYPT 34 #include <gcrypt.h> 35 #elif CONFIG_OPENSSL 36 #include <openssl/rand.h> 37 #endif 38 #include <fcntl.h> 39 #include <math.h> 40 #include <time.h> 41 #include <string.h> 42 #include "avassert.h" 43 #include "file_open.h" 44 #include "internal.h" 45 #include "intreadwrite.h" 46 #include "timer.h" 47 #include "random_seed.h" 48 #include "sha.h" 49 50 #ifndef TEST 51 #define TEST 0 52 #endif 53 54 static int read_random(uint8_t *dst, size_t len, const char *file) 55 { 56 #if HAVE_UNISTD_H 57 FILE *fp = avpriv_fopen_utf8(file, "r"); 58 size_t err; 59 60 if (!fp) 61 return AVERROR_UNKNOWN; 62 setvbuf(fp, NULL, _IONBF, 0); 63 err = fread(dst, 1, len, fp); 64 fclose(fp); 65 66 if (err != len) 67 return AVERROR_UNKNOWN; 68 69 return 0; 70 #else 71 return AVERROR(ENOSYS); 72 #endif 73 } 74 75 static uint32_t get_generic_seed(void) 76 { 77 uint64_t tmp[120/8]; 78 struct AVSHA *sha = (void*)tmp; 79 clock_t last_t = 0; 80 clock_t last_td = 0; 81 clock_t init_t = 0; 82 static uint64_t i = 0; 83 static uint32_t buffer[512] = { 0 }; 84 unsigned char digest[20]; 85 uint64_t last_i = i; 86 87 av_assert0(sizeof(tmp) >= av_sha_size); 88 89 if(TEST){ 90 memset(buffer, 0, sizeof(buffer)); 91 last_i = i = 0; 92 }else{ 93 #ifdef AV_READ_TIME 94 buffer[13] ^= AV_READ_TIME(); 95 buffer[41] ^= AV_READ_TIME()>>32; 96 #endif 97 } 98 99 for (;;) { 100 clock_t t = clock(); 101 if (last_t + 2*last_td + (CLOCKS_PER_SEC > 1000) >= t) { 102 last_td = t - last_t; 103 buffer[i & 511] = 1664525*buffer[i & 511] + 1013904223 + (last_td % 3294638521U); 104 } else { 105 last_td = t - last_t; 106 buffer[++i & 511] += last_td % 3294638521U; 107 if ((t - init_t) >= CLOCKS_PER_SEC>>5) 108 if (last_i && i - last_i > 4 || i - last_i > 64 || TEST && i - last_i > 8) 109 break; 110 } 111 last_t = t; 112 if (!init_t) 113 init_t = t; 114 } 115 116 if(TEST) { 117 buffer[0] = buffer[1] = 0; 118 } else { 119 #ifdef AV_READ_TIME 120 buffer[111] += AV_READ_TIME(); 121 #endif 122 } 123 124 av_sha_init(sha, 160); 125 av_sha_update(sha, (const uint8_t *)buffer, sizeof(buffer)); 126 av_sha_final(sha, digest); 127 return AV_RB32(digest) + AV_RB32(digest + 16); 128 } 129 130 int av_random_bytes(uint8_t* buf, size_t len) 131 { 132 int err; 133 134 #if HAVE_BCRYPT 135 BCRYPT_ALG_HANDLE algo_handle; 136 NTSTATUS ret = BCryptOpenAlgorithmProvider(&algo_handle, BCRYPT_RNG_ALGORITHM, 137 MS_PRIMITIVE_PROVIDER, 0); 138 if (BCRYPT_SUCCESS(ret)) { 139 NTSTATUS ret = BCryptGenRandom(algo_handle, (PUCHAR)buf, len, 0); 140 BCryptCloseAlgorithmProvider(algo_handle, 0); 141 if (BCRYPT_SUCCESS(ret)) 142 return 0; 143 } 144 #endif 145 146 #if HAVE_ARC4RANDOM_BUF 147 arc4random_buf(buf, len); 148 return 0; 149 #endif 150 151 err = read_random(buf, len, "/dev/urandom"); 152 if (!err) 153 return err; 154 155 #if CONFIG_GCRYPT 156 gcry_randomize(buf, len, GCRY_VERY_STRONG_RANDOM); 157 return 0; 158 #elif CONFIG_OPENSSL 159 if (RAND_bytes(buf, len) == 1) 160 return 0; 161 return AVERROR_EXTERNAL; 162 #else 163 return err; 164 #endif 165 } 166 167 uint32_t av_get_random_seed(void) 168 { 169 uint32_t seed; 170 171 if (av_random_bytes((uint8_t *)&seed, sizeof(seed)) < 0) 172 return get_generic_seed(); 173 174 return seed; 175 }