53019f0459
[ Merge of http://go/wvgerrit/108103 ] The Widevine License Agreement has been renamed to use inclusive language. This covers files in the cdm, linux, platform, util directory in addition to some other files. Bug: 168562298 Test: verified compilation (comment only change) Change-Id: I9a4977fd4c2ad951769b6be84263f81bd0f22678
108 lines
3.1 KiB
C++
108 lines
3.1 KiB
C++
// Copyright 2019 Google LLC. All Rights Reserved. This file and proprietary
|
|
// source code may only be used and distributed under the Widevine License
|
|
// Agreement.
|
|
|
|
#include "cdm_random.h"
|
|
|
|
#include <stdlib.h>
|
|
|
|
#include <algorithm>
|
|
|
|
#include "log.h"
|
|
|
|
// This type alias is for convenience.
|
|
using CdmRandomLock = std::unique_lock<std::mutex>;
|
|
|
|
namespace wvcdm {
|
|
|
|
namespace {
|
|
// More information about C++11's random number generators can be found
|
|
// from the introductory paper https://isocpp.org/files/papers/n3551.pdf
|
|
|
|
// Attemps to get random data in a device specific manner. If the device
|
|
// does not support true random data, then a pseudo-random sequence might
|
|
// be used instead. The exact behaviour depends on the compiler and
|
|
// platform combination.
|
|
unsigned int GetDeviceRandomSeed() {
|
|
static std::random_device rdev;
|
|
static std::mutex rdev_mutex;
|
|
CdmRandomLock rdev_lock(rdev_mutex);
|
|
return rdev();
|
|
}
|
|
|
|
} // namespace
|
|
|
|
// CdmRandomGenerator.
|
|
|
|
CdmRandomGenerator::CdmRandomGenerator() : generator_(GetDeviceRandomSeed()) {}
|
|
|
|
void CdmRandomGenerator::Seed() {
|
|
CdmRandomLock lock(generator_lock_);
|
|
generator_.seed(GetDeviceRandomSeed());
|
|
}
|
|
|
|
void CdmRandomGenerator::Seed(unsigned int s) {
|
|
CdmRandomLock lock(generator_lock_);
|
|
generator_.seed(s);
|
|
}
|
|
|
|
unsigned int CdmRandomGenerator::Rand() {
|
|
CdmRandomLock lock(generator_lock_);
|
|
std::uniform_int_distribution<unsigned int> dist(0, RAND_MAX);
|
|
return dist(generator_);
|
|
}
|
|
|
|
uint64_t CdmRandomGenerator::RandomInRange(uint64_t lower, uint64_t upper) {
|
|
if (lower == upper) {
|
|
return lower;
|
|
}
|
|
CdmRandomLock lock(generator_lock_);
|
|
if (lower > upper) {
|
|
LOGW(
|
|
"Lower bound is larger than upper bound, swapping bounds: "
|
|
"lower = %llu, upper = %llu",
|
|
// Casting to insure this will work on 32-bit systems.
|
|
static_cast<unsigned long long>(lower),
|
|
static_cast<unsigned long long>(upper));
|
|
std::swap(lower, upper);
|
|
}
|
|
std::uniform_int_distribution<uint64_t> dist(lower, upper);
|
|
return dist(generator_);
|
|
}
|
|
|
|
std::string CdmRandomGenerator::RandomData(size_t length) {
|
|
if (length > kMaxRandomDataLength) {
|
|
LOGE("Maximum random data length exceeded: length = %zu, max_length = %zu",
|
|
length, kMaxRandomDataLength);
|
|
return std::string();
|
|
}
|
|
CdmRandomLock lock(generator_lock_);
|
|
std::uniform_int_distribution<uint8_t> dist; // Range of [0, 255].
|
|
std::string random_data(length, '\0');
|
|
std::generate(random_data.begin(), random_data.end(),
|
|
[&]() { return dist(generator_); });
|
|
return random_data;
|
|
}
|
|
|
|
bool CdmRandomGenerator::RandomBool() {
|
|
CdmRandomLock lock(generator_lock_);
|
|
std::bernoulli_distribution dist; // 50/50.
|
|
return dist(generator_);
|
|
}
|
|
|
|
// CdmRandom.
|
|
|
|
// static
|
|
CdmRandomGenerator* CdmRandom::GetInstance() {
|
|
static std::mutex g_instance_lock;
|
|
static CdmRandomGenerator* g_instance = nullptr;
|
|
CdmRandomLock lock(g_instance_lock);
|
|
if (g_instance == nullptr) {
|
|
LOGV("Initalizing CDM random number generator");
|
|
g_instance = new CdmRandomGenerator(GetDeviceRandomSeed());
|
|
}
|
|
return g_instance;
|
|
}
|
|
|
|
} // namespace wvcdm
|