yading@11: /*
yading@11:  * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
yading@11:  *
yading@11:  * This file is part of FFmpeg.
yading@11:  *
yading@11:  * FFmpeg is free software; you can redistribute it and/or
yading@11:  * modify it under the terms of the GNU Lesser General Public
yading@11:  * License as published by the Free Software Foundation; either
yading@11:  * version 2.1 of the License, or (at your option) any later version.
yading@11:  *
yading@11:  * FFmpeg is distributed in the hope that it will be useful,
yading@11:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@11:  * Lesser General Public License for more details.
yading@11:  *
yading@11:  * You should have received a copy of the GNU Lesser General Public
yading@11:  * License along with FFmpeg; if not, write to the Free Software
yading@11:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@11:  */
yading@11: 
yading@11: #include "config.h"
yading@11: 
yading@11: #if HAVE_UNISTD_H
yading@11: #include <unistd.h>
yading@11: #endif
yading@11: #if HAVE_CRYPTGENRANDOM
yading@11: #include <windows.h>
yading@11: #include <wincrypt.h>
yading@11: #endif
yading@11: #include <fcntl.h>
yading@11: #include <math.h>
yading@11: #include <time.h>
yading@11: #include <string.h>
yading@11: #include "avassert.h"
yading@11: #include "timer.h"
yading@11: #include "random_seed.h"
yading@11: #include "sha.h"
yading@11: #include "intreadwrite.h"
yading@11: 
yading@11: #ifndef TEST
yading@11: #define TEST 0
yading@11: #endif
yading@11: 
yading@11: static int read_random(uint32_t *dst, const char *file)
yading@11: {
yading@11: #if HAVE_UNISTD_H
yading@11:     int fd = open(file, O_RDONLY);
yading@11:     int err = -1;
yading@11: 
yading@11:     if (fd == -1)
yading@11:         return -1;
yading@11:     err = read(fd, dst, sizeof(*dst));
yading@11:     close(fd);
yading@11: 
yading@11:     return err;
yading@11: #else
yading@11:     return -1;
yading@11: #endif
yading@11: }
yading@11: 
yading@11: static uint32_t get_generic_seed(void)
yading@11: {
yading@11:     uint8_t tmp[120];
yading@11:     struct AVSHA *sha = (void*)tmp;
yading@11:     clock_t last_t  = 0;
yading@11:     static uint64_t i = 0;
yading@11:     static uint32_t buffer[512] = {0};
yading@11:     unsigned char digest[20];
yading@11:     uint64_t last_i = i;
yading@11: 
yading@11:     av_assert0(sizeof(tmp) >= av_sha_size);
yading@11: 
yading@11:     if(TEST){
yading@11:         memset(buffer, 0, sizeof(buffer));
yading@11:         last_i = i = 0;
yading@11:     }else{
yading@11: #ifdef AV_READ_TIME
yading@11:         buffer[13] ^= AV_READ_TIME();
yading@11:         buffer[41] ^= AV_READ_TIME()>>32;
yading@11: #endif
yading@11:     }
yading@11: 
yading@11:     for (;;) {
yading@11:         clock_t t = clock();
yading@11: 
yading@11:         if(last_t == t){
yading@11:             buffer[i&511]++;
yading@11:         }else{
yading@11:             buffer[++i&511]+= (t-last_t) % 3294638521U;
yading@11:             if(last_i && i-last_i > 4 || i-last_i > 64 || TEST && i-last_i > 8)
yading@11:                 break;
yading@11:         }
yading@11:         last_t = t;
yading@11:     }
yading@11: 
yading@11:     if(TEST)
yading@11:         buffer[0] = buffer[1] = 0;
yading@11: 
yading@11:     av_sha_init(sha, 160);
yading@11:     av_sha_update(sha, (uint8_t*)buffer, sizeof(buffer));
yading@11:     av_sha_final(sha, digest);
yading@11:     return AV_RB32(digest) + AV_RB32(digest+16);
yading@11: }
yading@11: 
yading@11: uint32_t av_get_random_seed(void)
yading@11: {
yading@11:     uint32_t seed;
yading@11: 
yading@11: #if HAVE_CRYPTGENRANDOM
yading@11:     HCRYPTPROV provider;
yading@11:     if (CryptAcquireContext(&provider, NULL, NULL, PROV_RSA_FULL,
yading@11:                             CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
yading@11:         BOOL ret = CryptGenRandom(provider, sizeof(seed), (PBYTE) &seed);
yading@11:         CryptReleaseContext(provider, 0);
yading@11:         if (ret)
yading@11:             return seed;
yading@11:     }
yading@11: #endif
yading@11: 
yading@11:     if (read_random(&seed, "/dev/urandom") == sizeof(seed))
yading@11:         return seed;
yading@11:     if (read_random(&seed, "/dev/random")  == sizeof(seed))
yading@11:         return seed;
yading@11:     return get_generic_seed();
yading@11: }
yading@11: 
yading@11: #if TEST
yading@11: #undef printf
yading@11: #define N 256
yading@11: #include <stdio.h>
yading@11: 
yading@11: int main(void)
yading@11: {
yading@11:     int i, j, retry;
yading@11:     uint32_t seeds[N];
yading@11: 
yading@11:     for (retry=0; retry<3; retry++){
yading@11:         for (i=0; i<N; i++){
yading@11:             seeds[i] = av_get_random_seed();
yading@11:             for (j=0; j<i; j++)
yading@11:                 if (seeds[j] == seeds[i])
yading@11:                     goto retry;
yading@11:         }
yading@11:         printf("seeds OK\n");
yading@11:         return 0;
yading@11:         retry:;
yading@11:     }
yading@11:     printf("FAIL at %d with %X\n", j, seeds[j]);
yading@11:     return 1;
yading@11: }
yading@11: #endif