accumulator: add urandom_entropy_src

CMakeLists.txt

@@ -183,7 +183,7 @@ add_subdirectory(lib/fmt EXCLUDE_FROM_ALL)
     endif(NOT CMAKE_EXE_LINKER_FLAGS MATCHES "-fuse-ld=lld")
   endif()
 
-add_executable(fortuna main.cpp generator.cpp generator.h fortuna.cpp fortuna.h accumulator.cpp accumulator.h pool.cpp pool.h event_adder.h event_adder_impl.h event_scheduler.h entropy_src.h)
+add_executable(fortuna main.cpp generator.cpp generator.h fortuna.cpp fortuna.h accumulator.cpp accumulator.h pool.cpp pool.h event_adder.h event_adder_impl.h event_scheduler.h entropy_src.h urandom_entropy_src.h)
 # ref: https://cmake.org/pipermail/cmake/2016-May/063400.html
 target_link_libraries(fortuna
     PRIVATE cryptopp

urandom_entropy_src.h

@@ -0,0 +1,46 @@
+#ifndef FORTUNA_URANDOM_ENTROPY_SRC_H
+#define FORTUNA_URANDOM_ENTROPY_SRC_H
+
+#include "entropy_src.h"
+
+#include <fmt/core.h>
+#include <fstream>
+
+namespace fortuna {
+namespace accumulator {
+
+class UrandomEntropySrc : public EntropySrc {
+public:
+	static constexpr const std::size_t max_event_length{32};
+
+	auto schedule(accumulator::EventScheduler scheduler) -> void {
+		scheduler.schedule(std::chrono::milliseconds(100));
+	}
+
+	auto event(accumulator::EventAdder adder) -> void {
+		std::ifstream file;
+		file.exceptions ( std::ifstream::failbit | std::ifstream::badbit );
+
+		try {
+			std::ifstream urandom("/dev/urandom", std::ios::in|std::ios::binary);
+			// check if stream is open
+			if(urandom) {
+				urandom.read(reinterpret_cast<char*>(&bytes), bytes.length());
+				urandom.close();
+			} else {
+				// open failed
+				fmt::print(stderr, "Failed to open /dev/urandom\n");
+			}
+		} catch(std::ifstream::failure& e) {
+			fmt::print("io exception caugth: {}\n", e.what());
+		}
+	}
+
+private:
+	static std::vector<char> bytes[max_event_length];
+};
+
+} //namespace accumulator
+} //namespace fortuna
+#endif//FORTUNA_URANDOM_ENTROPY_SRC_H
+