libresiprocate-1.9-dev 1.9.6-1 / usr / include / rutil / Random.hxx

#if !defined(RESIP_RANDOM_HXX)
#define RESIP_RANDOM_HXX 

#include "rutil/Mutex.hxx"
#include "rutil/Data.hxx"
#include "rutil/ThreadIf.hxx"     // for ThreadLocalStorage
#include <cassert>
struct random_data;

/**
 * Define below to enable "RtlGenRandom" (aka SystemFunction036) on
 * Windows platform. See Random.cxx for details.
 */
// #define RESIP_RANDOM_WIN32_RTL 1

/**
 * Define below to use common random number generator sate for all resip
 * threads, but private from other parts of app.
 * This makes use of random_r() and friends with mutex protection.
 */
// #define RESIP_RANDOM_THREAD_MUTEX 1

/**
 * Define below to use independent random number generator state
 * for each thread. This makes use of random_r() and friends
 * with TheadIf::tls (thread-local-storage).
 */
// #define RESIP_RANDOM_THREAD_LOCAL 1

/**
 * By default, on POSIX, the standard srandom() and random()
 * functions will be used. This shares the generator state with
 * others libraries running in the same application. Under Linux
 * random() obtains a mutex so is threadsafe.
 * NOTE: See http://evanjones.ca/random-thread-safe.html for some good info.
 * WATCHOUT: Some other library can call srandom() in a stupid way,
 * causing duplicate callids and such.
 */


namespace resip
{

/**
   @brief A static class that wraps the random-number generation code of your
      platform.
   @ingroup crypto
*/
class Random
{
   public:
      static unsigned getSimpleSeed();
      static void initialize();

      enum {maxLength = 512};
      
      static Data getRandom(unsigned int numBytes);
      static Data getRandomHex(unsigned int numBytes); // actual length is 2*numBytes
      static Data getRandomBase64(unsigned int numBytes); // actual length is 1.5*numBytes

      static Data getCryptoRandom(unsigned int numBytes);
      static Data getCryptoRandomHex(unsigned int numBytes); // actual length is 2*numBytes
      static Data getCryptoRandomBase64(unsigned int numBytes); // actual length is 1.5*numBytes

      static void getCryptoRandom(unsigned char* buf, unsigned int numBytes);

      /**
        Returns a version 4 (random) UUID as defined in RFC 4122

        @todo This is something of a suboptimal hack. Ideally, we would
              encapsulate UUID as its own class, with options to create
              any of versions 1 through 5 (and Nil UUIDs). This class
              would have various access methods to pull the result out
              as a bitstring, as raw data, as a URN, etc. For what
              I need to do right now, however, version 4 UUIDs get me
              where I need to go. <abr>
      */
      static Data getVersion4UuidUrn();

      /**
          Returns a postive integer (31 bits) of randomness. Implementation
          is platform dependent.
      **/
      static int  getRandom();
      static int  getCryptoRandom();

      static const char* getImplName();

   private:
      static Mutex mMutex;
      static bool  mIsInitialized;
      
#ifdef WIN32
      // ensure each thread is initialized since windows requires you to call srand for each thread
      ///@internal
      class Initializer
      {
         public:
            Initializer();
            ~Initializer();
            void setInitialized();
            bool isInitialized();

         private:
            DWORD mThreadStorage;
      };
      static Initializer mInitializer;

#ifdef RESIP_RANDOM_WIN32_RTL
      static BOOLEAN (APIENTRY *RtlGenRandom)(void*, ULONG);
#endif
#endif  // WIN32
#ifdef RESIP_RANDOM_THREAD_LOCAL
      static ThreadIf::TlsKey sRandomStateKey;
#endif
#ifdef RESIP_RANDOM_THREAD_MUTEX
      static struct random_data* sRandomState;
      // we re-use the initialization mutex
#endif
};
 
}

#endif

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