core: unify randomization

Non-security randomizations are changed to use boost::random,
with a global random number generator.

refs #1369

Change-Id: I5000fd02f170fa47058af790e2bea767f9c65650
diff --git a/core/random.cpp b/core/random.cpp
new file mode 100644
index 0000000..51b137e
--- /dev/null
+++ b/core/random.cpp
@@ -0,0 +1,38 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014,  Regents of the University of California,
+ *                      Arizona Board of Regents,
+ *                      Colorado State University,
+ *                      University Pierre & Marie Curie, Sorbonne University,
+ *                      Washington University in St. Louis,
+ *                      Beijing Institute of Technology,
+ *                      The University of Memphis
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE.  See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NFD, e.g., in COPYING.md file.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "random.hpp"
+
+namespace nfd {
+
+static boost::random::mt19937 g_rng;
+
+boost::random::mt19937&
+getGlobalRng()
+{
+  return g_rng;
+}
+
+} // namespace nfd