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

Sources/OpenVPN3/openvpn/random/randapi.hpp

@@ -0,0 +1,152 @@
+//    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/>.
+
+// API for random number implementations.
+
+#ifndef OPENVPN_MBEDTLS_UTIL_RANDAPI_H
+#define OPENVPN_MBEDTLS_UTIL_RANDAPI_H
+
+#include <string>
+#include <cstdint>
+
+#include <openvpn/common/size.hpp>
+#include <openvpn/common/rc.hpp>
+#include <openvpn/common/exception.hpp>
+#include <openvpn/random/randistrib.hpp>
+
+namespace openvpn {
+
+  class RandomAPI : public RC<thread_unsafe_refcount>
+  {
+  public:
+    typedef RCPtr<RandomAPI> Ptr;
+
+    // Random algorithm name
+    virtual std::string name() const = 0;
+
+    // Return true if algorithm is crypto-strength
+    virtual bool is_crypto() const = 0;
+
+    // Fill buffer with random bytes
+    virtual void rand_bytes(unsigned char *buf, size_t size) = 0;
+
+    // Like rand_bytes, but don't throw exception.
+    // Return true on successs, false on fail.
+    virtual bool rand_bytes_noexcept(unsigned char *buf, size_t size) = 0;
+
+    // Fill a data object with random bits
+    template <typename T>
+    void rand_fill(T& obj)
+    {
+      rand_bytes(reinterpret_cast<unsigned char *>(&obj), sizeof(T));
+    }
+
+    // Return a data object with random bits
+    template <typename T>
+    T rand_get()
+    {
+      T ret;
+      rand_fill(ret);
+      return ret;
+    }
+
+    // Return a data object with random bits, always >= 0 for signed types
+    template <typename T>
+    T rand_get_positive()
+    {
+      T ret = rand_get<T>();
+      if (ret < 0)
+	ret = -ret;
+      return ret;
+    }
+
+    // Return a uniformly distributed random number in the range [0, end).
+    // end must be > 0.
+    template <typename T>
+    T randrange(const T end)
+    {
+      return rand_get_positive<T>() % end;
+    }
+
+    // Return a uniformly distributed random number in the range [start, end].
+    template <typename T>
+    T randrange(const T start, const T end)
+    {
+      if (start >= end)
+	return start;
+      else
+	return start + rand_get_positive<T>() % (end - start + 1);
+    }
+
+    // Return a uniformly distributed random number in the range [0, end).
+    // This version is strictly 32-bit only and optimizes by avoiding
+    // integer division.
+    std::uint32_t randrange32(const std::uint32_t end)
+    {
+      std::uint32_t r;
+      rand_fill(r);
+      return rand32_distribute(r, end);
+    }
+
+    // Return a uniformly distributed random number in the range [start, end].
+    // This version is strictly 32-bit only and optimizes by avoiding
+    // integer division.
+    std::uint32_t randrange32(const std::uint32_t start, const std::uint32_t end)
+    {
+      if (start >= end)
+	return start;
+      else
+	return start + randrange32(end - start + 1);
+    }
+
+    // Return a random byte
+    std::uint8_t randbyte()
+    {
+      std::uint8_t byte;
+      rand_fill(byte);
+      return byte;
+    }
+
+    // Return a random boolean
+    bool randbool()
+    {
+      return bool(randbyte() & 1);
+    }
+
+    // Throw an exception if algorithm is not crypto-strength.
+    // Be sure to always call this method before using an rng
+    // for crypto purposes.
+    void assert_crypto() const
+    {
+      if (!is_crypto())
+	throw Exception("RandomAPI: " + name() + " algorithm is not crypto-strength");
+    }
+
+    // UniformRandomBitGenerator for std::shuffle
+    typedef unsigned int result_type;
+    static constexpr result_type min() { return result_type(0); }
+    static constexpr result_type max() { return ~result_type(0); }
+    result_type operator()() { return rand_get<result_type>(); }
+  };
+
+}
+
+#endif