ceph/src/boost/boost/beast/websocket/detail/prng.ipp

   1 //
   2 // Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail dot com)
   3 //
   4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // Official repository: https://github.com/boostorg/beast
   8 //
   9
  10 #ifndef BOOST_BEAST_WEBSOCKET_DETAIL_PRNG_IPP
  11 #define BOOST_BEAST_WEBSOCKET_DETAIL_PRNG_IPP
  12
  13 #include <boost/beast/websocket/detail/prng.hpp>
  14 #include <boost/beast/core/detail/chacha.hpp>
  15 #include <boost/beast/core/detail/pcg.hpp>
  16 #include <atomic>
  17 #include <cstdlib>
  18 #include <mutex>
  19 #include <random>
  20
  21 namespace boost {
  22 namespace beast {
  23 namespace websocket {
  24 namespace detail {
  25
  26 //------------------------------------------------------------------------------
  27
  28 std::uint32_t const*
  29 prng_seed(std::seed_seq* ss)
  30 {
  31     struct data
  32     {
  33         std::uint32_t v[8];
  34
  35         explicit
  36         data(std::seed_seq* pss)
  37         {
  38             if(! pss)
  39             {
  40                 std::random_device g;
  41                 std::seed_seq ss{
  42                     g(), g(), g(), g(),
  43                     g(), g(), g(), g()};
  44                 ss.generate(v, v+8);
  45             }
  46             else
  47             {
  48                 pss->generate(v, v+8);
  49             }
  50         }
  51     };
  52     static data const d(ss);
  53     return d.v;
  54 }
  55
  56 //------------------------------------------------------------------------------
  57
  58 inline
  59 std::uint32_t
  60 make_nonce()
  61 {
  62     static std::atomic<std::uint32_t> nonce{0};
  63     return ++nonce;
  64 }
  65
  66 inline
  67 beast::detail::pcg make_pcg()
  68 {
  69     auto const pv = prng_seed();
  70     return beast::detail::pcg{
  71         ((static_cast<std::uint64_t>(pv[0])<<32)+pv[1]) ^
  72         ((static_cast<std::uint64_t>(pv[2])<<32)+pv[3]) ^
  73         ((static_cast<std::uint64_t>(pv[4])<<32)+pv[5]) ^
  74         ((static_cast<std::uint64_t>(pv[6])<<32)+pv[7]), make_nonce()};
  75 }
  76
  77 #ifdef BOOST_NO_CXX11_THREAD_LOCAL
  78
  79 inline
  80 std::uint32_t
  81 secure_generate()
  82 {
  83     struct generator
  84     {
  85         std::uint32_t operator()()
  86         {
  87             std::lock_guard<std::mutex> guard{mtx};
  88             return gen();
  89         }
  90
  91         beast::detail::chacha<20> gen;
  92         std::mutex mtx;
  93     };
  94     static generator gen{beast::detail::chacha<20>{prng_seed(), make_nonce()}};
  95     return gen();
  96 }
  97
  98 inline
  99 std::uint32_t
 100 fast_generate()
 101 {
 102     struct generator
 103     {
 104         std::uint32_t operator()()
 105         {
 106             std::lock_guard<std::mutex> guard{mtx};
 107             return gen();
 108         }
 109
 110         beast::detail::pcg gen;
 111         std::mutex mtx;
 112     };
 113     static generator gen{make_pcg()};
 114     return gen();
 115 }
 116
 117 #else
 118
 119 inline
 120 std::uint32_t
 121 secure_generate()
 122 {
 123     thread_local static beast::detail::chacha<20> gen{prng_seed(), make_nonce()};
 124     return gen();
 125 }
 126
 127 inline
 128 std::uint32_t
 129 fast_generate()
 130 {
 131     thread_local static beast::detail::pcg gen{make_pcg()};
 132     return gen();
 133 }
 134
 135 #endif
 136
 137 generator
 138 make_prng(bool secure)
 139 {
 140     if (secure)
 141         return &secure_generate;
 142     else
 143         return &fast_generate;
 144 }
 145
 146 } // detail
 147 } // websocket
 148 } // beast
 149 } // boost
 150
 151 #endif