56 lines
2.0 KiB
C++
56 lines
2.0 KiB
C++
// Copyright (c) Microsoft Corporation.
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// Licensed under the MIT license.
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#include <pcg_random.hpp>
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namespace til
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{
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namespace details
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{
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typedef BOOLEAN(APIENTRY* RtlGenRandom)(PVOID RandomBuffer, ULONG RandomBufferLength);
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struct RtlGenRandomLoader
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{
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RtlGenRandomLoader() noexcept :
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// The documentation states:
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// This function has no associated import library. This function is available
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// as a resource named SystemFunction036 in Advapi32.dll. You must use the
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// LoadLibrary and GetProcAddress functions to dynamically link to Advapi32.dll.
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//
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// There's two downsides to using advapi32.dll however:
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// * The actual implementation resides in cryptbase.dll and...
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// * In older versions of Windows (7 and older) advapi32.dll didn't use forwarding to
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// cryptbase, instead it was using LoadLibrary()/GetProcAddress() on every call.
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// * advapi32.dll doesn't exist on MinWin, cryptbase.dll however does.
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module{ LoadLibraryExW(L"cryptbase.dll", nullptr, LOAD_LIBRARY_SEARCH_SYSTEM32) },
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proc{ reinterpret_cast<decltype(proc)>(GetProcAddress(module.get(), "SystemFunction036")) }
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{
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FAIL_FAST_LAST_ERROR_IF(!proc);
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}
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inline void operator()(PVOID RandomBuffer, ULONG RandomBufferLength)
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{
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proc(RandomBuffer, RandomBufferLength);
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}
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private:
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wil::unique_hmodule module;
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RtlGenRandom proc;
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};
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}
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inline void gen_random(void* data, uint32_t length)
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{
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static details::RtlGenRandomLoader loader;
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loader(data, length);
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}
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template<typename T, typename = std::enable_if_t<std::is_standard_layout_v<T>>>
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T gen_random()
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{
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T value;
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gen_random(&value, sizeof(T));
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return value;
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}
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}
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