API endpoint for reading random numbers from the witness (#113)

libraries/app/database_api.cpp

@@ -184,6 +184,9 @@ class database_api_impl : public std::enable_shared_from_this<database_api_impl>
       // gpos
       gpos_info get_gpos_info(const account_id_type account) const;
 
+      // rng
+      int64_t get_random_number(uint64_t bound) const;
+
    //private:
       const account_object* get_account_from_string( const std::string& name_or_id,
                                                      bool throw_if_not_found = true ) const;
@@ -2303,6 +2306,22 @@ graphene::app::gpos_info database_api_impl::get_gpos_info(const account_id_type
    return result;
 }
 
+//////////////////////////////////////////////////////////////////////
+//                                                                  //
+// Random numbers                                                   //
+//                                                                  //
+//////////////////////////////////////////////////////////////////////
+
+int64_t database_api::get_random_number(uint64_t bound) const
+{
+   return my->get_random_number(bound);
+}
+
+int64_t database_api_impl::get_random_number(uint64_t bound) const {
+    int64_t result = _db.get_random_bits(bound);
+    return result;
+}
+
 //////////////////////////////////////////////////////////////////////
 //                                                                  //
 // Private methods                                                  //

libraries/app/include/graphene/app/database_api.hpp

@@ -709,9 +709,17 @@ class database_api
        */
       gpos_info get_gpos_info(const account_id_type account) const;
 
+      /////////////////////////////
+      // Random number generator //
+      /////////////////////////////
+      /**
+       * @brief Returns the random number
+       * @param bound Upper bound of segment containing random number
+       * @return Random number from segment [0, bound)
+       */
+      int64_t get_random_number(uint64_t bound) const;
 
-
+   private:
-private:
       std::shared_ptr< database_api_impl > my;
 };
 
@@ -848,4 +856,7 @@ FC_API(graphene::app::database_api,
 
    // gpos
    (get_gpos_info)
+
+   // rngs
+   (get_random_number)
 )