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