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70 lines
2.1 KiB
C++
70 lines
2.1 KiB
C++
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// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2019 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <randomenv.h>
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#include <crypto/sha512.h>
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#include <support/cleanse.h>
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#include <util/time.h> // for GetTime()
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#ifdef WIN32
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#include <compat.h> // for Windows API
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#endif
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#include <algorithm>
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#include <vector>
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#include <stdint.h>
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namespace {
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void RandAddSeedPerfmon(CSHA512& hasher)
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{
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#ifdef WIN32
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// Don't need this on Linux, OpenSSL automatically uses /dev/urandom
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// Seed with the entire set of perfmon data
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// This can take up to 2 seconds, so only do it every 10 minutes
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static int64_t nLastPerfmon;
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if (GetTime() < nLastPerfmon + 10 * 60)
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return;
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nLastPerfmon = GetTime();
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std::vector<unsigned char> vData(250000, 0);
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long ret = 0;
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unsigned long nSize = 0;
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const size_t nMaxSize = 10000000; // Bail out at more than 10MB of performance data
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while (true) {
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nSize = vData.size();
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ret = RegQueryValueExA(HKEY_PERFORMANCE_DATA, "Global", nullptr, nullptr, vData.data(), &nSize);
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if (ret != ERROR_MORE_DATA || vData.size() >= nMaxSize)
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break;
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vData.resize(std::max((vData.size() * 3) / 2, nMaxSize)); // Grow size of buffer exponentially
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}
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RegCloseKey(HKEY_PERFORMANCE_DATA);
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if (ret == ERROR_SUCCESS) {
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hasher.Write(vData.data(), nSize);
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memory_cleanse(vData.data(), nSize);
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} else {
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// Performance data is only a best-effort attempt at improving the
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// situation when the OS randomness (and other sources) aren't
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// adequate. As a result, failure to read it is isn't considered critical,
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// so we don't call RandFailure().
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// TODO: Add logging when the logger is made functional before global
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// constructors have been invoked.
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}
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#endif
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}
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} // namespace
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void RandAddDynamicEnv(CSHA512& hasher)
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{
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RandAddSeedPerfmon(hasher);
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}
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void RandAddStaticEnv(CSHA512& hasher)
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{
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}
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