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//
// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Official repository: https://github.com/boostorg/beast
//
#ifndef BOOST_BEAST_WEBSOCKET_DETAIL_PRNG_IPP
#define BOOST_BEAST_WEBSOCKET_DETAIL_PRNG_IPP
#include <boost/beast/websocket/detail/prng.hpp>
#include <boost/beast/core/detail/chacha.hpp>
#include <boost/beast/core/detail/pcg.hpp>
#include <atomic>
#include <cstdlib>
#include <mutex>
#include <random>
namespace boost {
namespace beast {
namespace websocket {
namespace detail {
//------------------------------------------------------------------------------
std::uint32_t const*
prng_seed(std::seed_seq* ss)
{
struct data
{
std::uint32_t v[8];
explicit
data(std::seed_seq* pss)
{
if(! pss)
{
std::random_device g;
std::seed_seq ss{
g(), g(), g(), g(),
g(), g(), g(), g()};
ss.generate(v, v+8);
}
else
{
pss->generate(v, v+8);
}
}
};
static data const d(ss);
return d.v;
}
//------------------------------------------------------------------------------
inline
std::uint32_t
make_nonce()
{
static std::atomic<std::uint32_t> nonce{0};
return ++nonce;
}
inline
beast::detail::pcg make_pcg()
{
auto const pv = prng_seed();
return beast::detail::pcg{
((static_cast<std::uint64_t>(pv[0])<<32)+pv[1]) ^
((static_cast<std::uint64_t>(pv[2])<<32)+pv[3]) ^
((static_cast<std::uint64_t>(pv[4])<<32)+pv[5]) ^
((static_cast<std::uint64_t>(pv[6])<<32)+pv[7]), make_nonce()};
}
#ifdef BOOST_NO_CXX11_THREAD_LOCAL
inline
std::uint32_t
secure_generate()
{
struct generator
{
std::uint32_t operator()()
{
std::lock_guard<std::mutex> guard{mtx};
return gen();
}
beast::detail::chacha<20> gen;
std::mutex mtx;
};
static generator gen{beast::detail::chacha<20>{prng_seed(), make_nonce()}};
return gen();
}
inline
std::uint32_t
fast_generate()
{
struct generator
{
std::uint32_t operator()()
{
std::lock_guard<std::mutex> guard{mtx};
return gen();
}
beast::detail::pcg gen;
std::mutex mtx;
};
static generator gen{make_pcg()};
return gen();
}
#else
inline
std::uint32_t
secure_generate()
{
thread_local static beast::detail::chacha<20> gen{prng_seed(), make_nonce()};
return gen();
}
inline
std::uint32_t
fast_generate()
{
thread_local static beast::detail::pcg gen{make_pcg()};
return gen();
}
#endif
generator
make_prng(bool secure)
{
if (secure)
return &secure_generate;
else
return &fast_generate;
}
} // detail
} // websocket
} // beast
} // boost
#endif
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