Merge commit '86cc97e55fe346502462284d2e636a2b3708163e' as 'Sources/OpenVPN3'

Sources/OpenVPN3/openvpn/random/randbytestore.hpp

@@ -0,0 +1,67 @@
+//    OpenVPN -- An application to securely tunnel IP networks
+//               over a single port, with support for SSL/TLS-based
+//               session authentication and key exchange,
+//               packet encryption, packet authentication, and
+//               packet compression.
+//
+//    Copyright (C) 2012-2017 OpenVPN Inc.
+//
+//    This program is free software: you can redistribute it and/or modify
+//    it under the terms of the GNU Affero General Public License Version 3
+//    as published by the Free Software Foundation.
+//
+//    This program 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 Affero General Public License for more details.
+//
+//    You should have received a copy of the GNU Affero General Public License
+//    along with this program in the COPYING file.
+//    If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef OPENVPN_RANDOM_RANDBYTESTORE_H
+#define OPENVPN_RANDOM_RANDBYTESTORE_H
+
+#include <openvpn/common/size.hpp>
+
+namespace openvpn {
+
+  template <typename RAND_TYPE>
+  class RandomByteStore
+  {
+  public:
+    static constexpr size_t SIZE = sizeof(typename RAND_TYPE::result_type);
+
+    unsigned char get_byte(RAND_TYPE& rng)
+    {
+      if (n_bytes == 0)
+	{
+	  res.rt = rng();
+	  n_bytes = SIZE;
+	}
+      unsigned char ret = res.bytes[0];
+      res.rt >>= 8;
+      --n_bytes;
+      return ret;
+    }
+
+    template <typename T>
+    void fill(T& obj, RAND_TYPE& rng)
+    {
+      unsigned char *data = reinterpret_cast<unsigned char *>(&obj);
+      for (size_t i = 0; i < sizeof(obj); ++i)
+	data[i] = get_byte(rng);
+    }
+
+  private:
+    union Result {
+      unsigned char bytes[SIZE];
+      typename RAND_TYPE::result_type rt;
+    };
+
+    Result res;
+    unsigned int n_bytes = 0;
+  };
+
+}
+#endif