boost/beast/websocket/detail/mask.hpp
//
// 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_MASK_HPP
#define BOOST_BEAST_WEBSOCKET_DETAIL_MASK_HPP
#include <boost/beast/core/detail/config.hpp>
#include <boost/beast/core/buffers_range.hpp>
#include <boost/asio/buffer.hpp>
#include <array>
#include <climits>
#include <cstdint>
#include <random>
#include <type_traits>
namespace boost {
namespace beast {
namespace websocket {
namespace detail {
using prepared_key = std::array<unsigned char, 4>;
inline
void
prepare_key(prepared_key& prepared, std::uint32_t key)
{
prepared[0] = (key >> 0) & 0xff;
prepared[1] = (key >> 8) & 0xff;
prepared[2] = (key >> 16) & 0xff;
prepared[3] = (key >> 24) & 0xff;
}
template<std::size_t N>
void
rol(std::array<unsigned char, N>& v, std::size_t n)
{
auto v0 = v;
for(std::size_t i = 0; i < v.size(); ++i )
v[i] = v0[(i + n) % v.size()];
}
// Apply mask in place
//
inline
void
mask_inplace(net::mutable_buffer& b, prepared_key& key)
{
auto n = b.size();
auto mask = key; // avoid aliasing
auto p = static_cast<unsigned char*>(b.data());
while(n >= 4)
{
for(int i = 0; i < 4; ++i)
p[i] ^= mask[i];
p += 4;
n -= 4;
}
if(n > 0)
{
for(std::size_t i = 0; i < n; ++i)
p[i] ^= mask[i];
rol(key, n);
}
}
// Apply mask in place
//
template<
class MutableBufferSequence,
class KeyType>
void
mask_inplace(
MutableBufferSequence const& buffers,
KeyType& key)
{
for(net::mutable_buffer b :
beast::buffers_range_ref(buffers))
mask_inplace(b, key);
}
} // detail
} // websocket
} // beast
} // boost
#endif