forked from boostorg/beast
149 lines
2.9 KiB
C++
149 lines
2.9 KiB
C++
//
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// Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// Official repository: https://github.com/boostorg/beast
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//
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#ifndef BOOST_BEAST_WEBSOCKET_DETAIL_MASK_HPP
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#define BOOST_BEAST_WEBSOCKET_DETAIL_MASK_HPP
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#include <boost/beast/core/detail/config.hpp>
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#include <boost/beast/core/detail/type_traits.hpp>
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#include <boost/asio/buffer.hpp>
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#include <array>
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#include <climits>
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#include <cstdint>
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#include <random>
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#include <type_traits>
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namespace boost {
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namespace beast {
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namespace websocket {
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namespace detail {
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// Pseudo-random source of mask keys
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//
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template<class Generator>
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class maskgen_t
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{
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Generator g_;
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public:
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using result_type =
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typename Generator::result_type;
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maskgen_t();
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result_type
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operator()() noexcept;
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void
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rekey();
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};
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template<class Generator>
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maskgen_t<Generator>::maskgen_t()
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{
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rekey();
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}
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template<class Generator>
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auto
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maskgen_t<Generator>::operator()() noexcept ->
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result_type
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{
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for(;;)
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if(auto key = g_())
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return key;
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}
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template<class _>
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void
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maskgen_t<_>::rekey()
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{
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std::random_device rng;
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#if 0
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std::array<std::uint32_t, 32> e;
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for(auto& i : e)
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i = rng();
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// VFALCO This constructor causes
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// address sanitizer to fail, no idea why.
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std::seed_seq ss(e.begin(), e.end());
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g_.seed(ss);
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#else
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g_.seed(rng());
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#endif
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}
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// VFALCO NOTE This generator has 5KB of state!
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//using maskgen = maskgen_t<std::mt19937>;
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using maskgen = maskgen_t<std::minstd_rand>;
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//------------------------------------------------------------------------------
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using prepared_key = std::array<unsigned char, 4>;
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inline
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void
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prepare_key(prepared_key& prepared, std::uint32_t key)
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{
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prepared[0] = (key >> 0) & 0xff;
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prepared[1] = (key >> 8) & 0xff;
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prepared[2] = (key >> 16) & 0xff;
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prepared[3] = (key >> 24) & 0xff;
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}
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template<std::size_t N>
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void
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rol(std::array<unsigned char, N>& v, unsigned n)
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{
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auto v0 = v;
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for(std::size_t i = 0; i < v.size(); ++i )
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v[i] = v0[(i + n) % v.size()];
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}
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// Apply mask in place
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//
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inline
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void
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mask_inplace(boost::asio::mutable_buffer& b, prepared_key& key)
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{
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auto n = b.size();
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auto mask = key; // avoid aliasing
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auto p = reinterpret_cast<unsigned char*>(b.data());
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while(n >= 4)
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{
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for(int i = 0; i < 4; ++i)
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p[i] ^= mask[i];
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p += 4;
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n -= 4;
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}
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if(n > 0)
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{
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for(std::size_t i = 0; i < n; ++i)
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p[i] ^= mask[i];
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rol(key, 4 - n);
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}
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}
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// Apply mask in place
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//
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template<class MutableBuffers, class KeyType>
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void
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mask_inplace(MutableBuffers const& bs, KeyType& key)
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{
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for(boost::asio::mutable_buffer b :
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beast::detail::buffers_range(bs))
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mask_inplace(b, key);
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}
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} // detail
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} // websocket
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} // beast
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} // boost
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#endif
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