util: add random::getRandomNumberEngine() to the public API
Change-Id: I03d572e3c51a7256f53060e66c9eae0d1ab84c65
diff --git a/ndn-cxx/util/random.cpp b/ndn-cxx/util/random.cpp
index 140b23b..92a5f32 100644
--- a/ndn-cxx/util/random.cpp
+++ b/ndn-cxx/util/random.cpp
@@ -22,8 +22,6 @@
#include "ndn-cxx/util/random.hpp"
#include "ndn-cxx/security/impl/openssl.hpp"
-#include <random>
-
namespace ndn {
namespace random {
@@ -52,31 +50,30 @@
}
}
-static std::mt19937&
-getRandomGenerator()
+RandomNumberEngine&
+getRandomNumberEngine()
{
- static optional<std::mt19937> rng;
- if (!rng) {
+ thread_local std::mt19937 rng = [] {
std::random_device rd;
// seed with 256 bits of entropy
std::seed_seq seeds{rd(), rd(), rd(), rd(), rd(), rd(), rd(), rd()};
- rng.emplace(seeds);
- }
- return *rng;
+ return std::mt19937{seeds};
+ }();
+ return rng;
}
uint32_t
generateWord32()
{
- static std::uniform_int_distribution<uint32_t> distribution;
- return distribution(getRandomGenerator());
+ thread_local std::uniform_int_distribution<uint32_t> distribution;
+ return distribution(getRandomNumberEngine());
}
uint64_t
generateWord64()
{
- static std::uniform_int_distribution<uint64_t> distribution;
- return distribution(getRandomGenerator());
+ thread_local std::uniform_int_distribution<uint64_t> distribution;
+ return distribution(getRandomNumberEngine());
}
} // namespace random
diff --git a/ndn-cxx/util/random.hpp b/ndn-cxx/util/random.hpp
index 8f538b2..9c69bd0 100644
--- a/ndn-cxx/util/random.hpp
+++ b/ndn-cxx/util/random.hpp
@@ -1,6 +1,6 @@
/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2019 Regents of the University of California.
*
* This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
*
@@ -24,6 +24,8 @@
#include "ndn-cxx/detail/common.hpp"
+#include <random>
+
namespace ndn {
namespace random {
@@ -51,6 +53,17 @@
void
generateSecureBytes(uint8_t* bytes, size_t size);
+using RandomNumberEngine = std::mt19937;
+
+/**
+ * @brief Returns a reference to a thread-local instance of a properly seeded PRNG
+ *
+ * @warning The returned RandomNumberEngine MUST NOT be used when cryptographically secure
+ * random numbers are needed.
+ */
+RandomNumberEngine&
+getRandomNumberEngine();
+
/**
* @brief Generate a non-cryptographically-secure random integer in the range [0, 2^32)
*
diff --git a/tests/unit/util/random.t.cpp b/tests/unit/util/random.t.cpp
index 9cf7325..1aeca1a 100644
--- a/tests/unit/util/random.t.cpp
+++ b/tests/unit/util/random.t.cpp
@@ -1,6 +1,6 @@
/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
- * Copyright (c) 2013-2018 Regents of the University of California.
+ * Copyright (c) 2013-2019 Regents of the University of California.
*
* This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
*
@@ -24,8 +24,11 @@
#include "tests/boost-test.hpp"
-#include <boost/mpl/vector.hpp>
+#include <array>
#include <cmath>
+#include <thread>
+
+#include <boost/mpl/vector.hpp>
namespace ndn {
namespace tests {
@@ -33,6 +36,19 @@
BOOST_AUTO_TEST_SUITE(Util)
BOOST_AUTO_TEST_SUITE(TestRandom)
+BOOST_AUTO_TEST_CASE(ThreadLocalRng)
+{
+ random::RandomNumberEngine* r1 = &random::getRandomNumberEngine();
+ random::RandomNumberEngine* r2 = nullptr;
+ std::thread t([&r2] { r2 = &random::getRandomNumberEngine(); });
+ t.join();
+ random::RandomNumberEngine* r3 = &random::getRandomNumberEngine();
+
+ BOOST_CHECK(r2 != nullptr);
+ BOOST_CHECK_NE(r1, r2);
+ BOOST_CHECK_EQUAL(r1, r3);
+}
+
class PseudoRandomWord32
{
public:
@@ -73,11 +89,10 @@
}
};
-typedef boost::mpl::vector<PseudoRandomWord32,
- PseudoRandomWord64,
- SecureRandomWord32,
- SecureRandomWord64> RandomGenerators;
-
+using RandomGenerators = boost::mpl::vector<PseudoRandomWord32,
+ PseudoRandomWord64,
+ SecureRandomWord32,
+ SecureRandomWord64>;
static double
getDeviation(const std::vector<uint32_t>& counts, size_t size)
@@ -100,40 +115,37 @@
return t;
}
-
BOOST_AUTO_TEST_CASE_TEMPLATE(GoodnessOfFit, RandomGenerator, RandomGenerators)
{
const size_t MAX_BINS = 32;
const uint32_t MAX_ITERATIONS = 35;
std::vector<uint32_t> counts(MAX_BINS, 0);
-
for (uint32_t i = 0; i < MAX_ITERATIONS; i++) {
counts[RandomGenerator::generate() % MAX_BINS]++;
}
// Check if it is uniform distribution with confidence 0.95
// http://dlc.erieri.com/onlinetextbook/index.cfm?fuseaction=textbook.appendix&FileName=Table7
- BOOST_WARN_LE(getDeviation(counts, MAX_ITERATIONS), 0.230);
+ BOOST_CHECK_LE(getDeviation(counts, MAX_ITERATIONS), 0.230);
}
-BOOST_AUTO_TEST_CASE(GenerateRandomBytes)
+BOOST_AUTO_TEST_CASE(GenerateSecureBytes)
{
// Kolmogorov-Smirnov Goodness-of-Fit Test
// http://www.itl.nist.gov/div898/handbook/eda/section3/eda35g.htm
- uint8_t buf[1024] = {0};
- random::generateSecureBytes(buf, sizeof(buf));
+ std::array<uint8_t, 1024> buf;
+ random::generateSecureBytes(buf.data(), buf.size());
std::vector<uint32_t> counts(256, 0);
-
- for (size_t i = 0; i < sizeof(buf); i++) {
+ for (size_t i = 0; i < buf.size(); i++) {
counts[buf[i]]++;
}
// Check if it is uniform distribution with confidence 0.95
// http://dlc.erieri.com/onlinetextbook/index.cfm?fuseaction=textbook.appendix&FileName=Table7
- BOOST_WARN_LE(getDeviation(counts, sizeof(buf)), 0.230);
+ BOOST_CHECK_LE(getDeviation(counts, buf.size()), 0.230);
}
// This fixture uses OpenSSL routines to set a dummy random generator that always fails
@@ -214,8 +226,8 @@
BOOST_FIXTURE_TEST_CASE(Error, FailRandMethodFixture)
{
- uint8_t buf[1024] = {0};
- BOOST_CHECK_THROW(random::generateSecureBytes(buf, sizeof(buf)), std::runtime_error);
+ std::array<uint8_t, 1024> buf;
+ BOOST_CHECK_THROW(random::generateSecureBytes(buf.data(), buf.size()), std::runtime_error);
}
BOOST_AUTO_TEST_SUITE_END() // TestRandom