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qBittorrent/src/base/utils/random.cpp
2018-05-09 17:06:22 +03:00

141 lines
3.8 KiB
C++

/*
* Bittorrent Client using Qt and libtorrent.
* Copyright (C) 2017 Mike Tzou
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* In addition, as a special exception, the copyright holders give permission to
* link this program with the OpenSSL project's "OpenSSL" library (or with
* modified versions of it that use the same license as the "OpenSSL" library),
* and distribute the linked executables. You must obey the GNU General Public
* License in all respects for all of the code used other than "OpenSSL". If you
* modify file(s), you may extend this exception to your version of the file(s),
* but you are not obligated to do so. If you do not wish to do so, delete this
* exception statement from your version.
*/
#include "random.h"
#include <limits>
#include <random>
#include <QtGlobal>
#ifdef Q_OS_WIN
#ifndef NOMINMAX
#define NOMINMAX
#endif
#include <Windows.h>
#include <Ntsecapi.h>
#else // Q_OS_WIN
#include <cstdio>
#endif
#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)
{
static RandomLayer layer;
// new distribution is cheap: https://stackoverflow.com/a/19036349
std::uniform_int_distribution<uint32_t> uniform(min, max);
return uniform(layer);
}