Merge pull request #8724 from Chocobo1/rand

Use RNG provided by OS
This commit is contained in:
sledgehammer999 2018-04-22 22:33:16 +03:00 committed by GitHub
commit b78899cb9a
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
2 changed files with 98 additions and 33 deletions

View file

@ -29,47 +29,113 @@
#include "random.h"
#include <cassert>
#include <chrono>
#include <limits>
#include <random>
#include <QtGlobal>
#ifdef Q_OS_MAC
#include <QThreadStorage>
#ifdef Q_OS_WIN
#ifndef NOMINMAX
#define NOMINMAX
#endif
#include <Windows.h>
#include <Ntsecapi.h>
#else // Q_OS_WIN
#include <cstdio>
#endif
// on some platform `std::random_device` may generate the same number sequence
static bool hasTrueRandomDevice{ std::random_device{}() != std::random_device{}() };
#include "misc.h"
namespace
{
#ifdef Q_OS_WIN
class RandomLayer
{
// need to satisfy UniformRandomBitGenerator requirements
public:
using result_type = uint32_t;
RandomLayer()
: m_rtlGenRandom {Utils::Misc::loadWinAPI<PRTLGENRANDOM>("Advapi32.dll", "SystemFunction036")}
{
if (!m_rtlGenRandom)
qFatal("Failed to load RtlGenRandom()");
}
static constexpr result_type min()
{
return std::numeric_limits<result_type>::min();
}
static constexpr result_type max()
{
return std::numeric_limits<result_type>::max();
}
result_type operator()()
{
result_type buf = 0;
const bool result = m_rtlGenRandom(&buf, sizeof(buf));
if (!result)
qFatal("RtlGenRandom() failed");
return buf;
}
private:
using PRTLGENRANDOM = BOOLEAN (WINAPI *)(PVOID, ULONG);
const PRTLGENRANDOM m_rtlGenRandom;
};
#else // Q_OS_WIN
class RandomLayer
{
// need to satisfy UniformRandomBitGenerator requirements
public:
using result_type = uint32_t;
RandomLayer()
: m_randDev {fopen("/dev/urandom", "rb")}
{
if (!m_randDev)
qFatal("Failed to open /dev/urandom");
}
~RandomLayer()
{
fclose(m_randDev);
}
static constexpr result_type min()
{
return std::numeric_limits<result_type>::min();
}
static constexpr result_type max()
{
return std::numeric_limits<result_type>::max();
}
result_type operator()() const
{
result_type buf = 0;
if (fread(&buf, sizeof(buf), 1, m_randDev) != 1)
qFatal("Read /dev/urandom error");
return buf;
}
private:
FILE *m_randDev;
};
#endif
}
uint32_t Utils::Random::rand(const uint32_t min, const uint32_t max)
{
#ifdef Q_OS_MAC // workaround for Apple xcode: https://stackoverflow.com/a/29929949
static QThreadStorage<std::mt19937> generator;
if (!generator.hasLocalData())
generator.localData().seed(
hasTrueRandomDevice
? std::random_device{}()
: (std::random_device::result_type) std::chrono::system_clock::now().time_since_epoch().count()
);
#else
static thread_local std::mt19937 generator{
hasTrueRandomDevice
? std::random_device{}()
: static_cast<std::random_device::result_type>(std::chrono::system_clock::now().time_since_epoch().count())
};
#endif
static RandomLayer layer;
// better replacement for `std::rand`, don't use this for real cryptography application
// min <= returned_value <= max
assert(min <= max);
// new distribution is cheap: http://stackoverflow.com/a/19036349
// new distribution is cheap: https://stackoverflow.com/a/19036349
std::uniform_int_distribution<uint32_t> uniform(min, max);
#ifdef Q_OS_MAC
return uniform(generator.localData());
#else
return uniform(generator);
#endif
return uniform(layer);
}

View file

@ -31,13 +31,12 @@
#define UTILS_RANDOM_H
#include <cstdint>
#include <cstdlib>
namespace Utils
{
namespace Random
{
uint32_t rand(uint32_t min = 0, uint32_t max = UINT32_MAX);
uint32_t rand(const uint32_t min = 0, const uint32_t max = UINT32_MAX);
}
}