Add System_RNG which is an instantiatable RNG that uses the system RNG

Previously you couldn't have an unique_ptr<RNG> that might point to
either a system rng or an autoseed rng depending on availability. That
was already needed in ffi and is useful elsewhere.

2 files changed, 32 insertions, 9 deletions

diff --git a/src/lib/rng/system_rng/system_rng.cpp b/src/lib/rng/system_rng/system_rng.cpp
index 1ab80669b..8b949d071 100644
--- a/src/lib/rng/system_rng/system_rng.cpp
+++ b/src/lib/rng/system_rng/system_rng.cpp
@@ -1,6 +1,6 @@
 /*
 * System RNG
-* (C) 2014 Jack Lloyd
+* (C) 2014,2015 Jack Lloyd
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -28,11 +28,11 @@ namespace Botan {
 
 namespace {
 
-class System_RNG : public RandomNumberGenerator
+class System_RNG_Impl : public RandomNumberGenerator
    {
    public:
-      System_RNG();
-      ~System_RNG();
+      System_RNG_Impl();
+      ~System_RNG_Impl();
 
       void randomize(byte buf[], size_t len) override;
 
@@ -51,7 +51,7 @@ class System_RNG : public RandomNumberGenerator
 #endif
    };
 
-System_RNG::System_RNG()
+System_RNG_Impl::System_RNG_Impl()
    {
 #if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
 
@@ -66,7 +66,7 @@ System_RNG::System_RNG()
 #endif
    }
 
-System_RNG::~System_RNG()
+System_RNG_Impl::~System_RNG_Impl()
    {
 #if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
    ::CryptReleaseContext(m_prov, 0);
@@ -76,7 +76,7 @@ System_RNG::~System_RNG()
 #endif
    }
 
-void System_RNG::randomize(byte buf[], size_t len)
+void System_RNG_Impl::randomize(byte buf[], size_t len)
    {
 #if defined(BOTAN_TARGET_OS_HAS_CRYPTGENRANDOM)
    ::CryptGenRandom(m_prov, static_cast<DWORD>(len), buf);
@@ -104,7 +104,7 @@ void System_RNG::randomize(byte buf[], size_t len)
 
 RandomNumberGenerator& system_rng()
    {
-   static System_RNG g_system_rng;
+   static System_RNG_Impl g_system_rng;
    return g_system_rng;
    }
 
diff --git a/src/lib/rng/system_rng/system_rng.h b/src/lib/rng/system_rng/system_rng.h
index cac861618..0f4b94725 100644
--- a/src/lib/rng/system_rng/system_rng.h
+++ b/src/lib/rng/system_rng/system_rng.h
@@ -1,6 +1,6 @@
 /*
 * System RNG interface
-* (C) 2014 Jack Lloyd
+* (C) 2014,2015 Jack Lloyd
 *
 * Botan is released under the Simplified BSD License (see license.txt)
 */
@@ -19,6 +19,29 @@ namespace Botan {
 */
 BOTAN_DLL RandomNumberGenerator& system_rng();
 
+/*
+* Instantiatable reference to the system RNG.
+*/
+class BOTAN_DLL System_RNG : public RandomNumberGenerator
+   {
+   public:
+      System_RNG() : m_rng(system_rng()) {}
+
+      void randomize(Botan::byte out[], size_t len) override { m_rng.randomize(out, len); }
+
+      bool is_seeded() const override { return m_rng.is_seeded(); }
+
+      void clear() override { m_rng.clear(); }
+
+      std::string name() const override { return m_rng.name(); }
+
+      void reseed(size_t poll_bits = 256) override { m_rng.reseed(poll_bits); }
+
+      void add_entropy(const byte in[], size_t len) override { m_rng.add_entropy(in, len); }
+   private:
+      Botan::RandomNumberGenerator& m_rng;
+   };
+
 }
 
 #endif