aboutsummaryrefslogtreecommitdiff
path: root/src/randomenv.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'src/randomenv.cpp')
-rw-r--r--src/randomenv.cpp69
1 files changed, 69 insertions, 0 deletions
diff --git a/src/randomenv.cpp b/src/randomenv.cpp
new file mode 100644
index 0000000000..529dd039b2
--- /dev/null
+++ b/src/randomenv.cpp
@@ -0,0 +1,69 @@
+// 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)
+{
+}