fortuna/fortuna.h

#ifndef FORTUNA_FORTUNA_H
#define FORTUNA_FORTUNA_H

#include "accumulator.h"
#include "generator.h"
#include "pool.h"

#include <fmt/core.h>

#include <array>
#include <chrono>
#include <memory>
#include <mutex>
#include <thread>

namespace fortuna {

class Fortuna {
public:
	static constexpr const char NUM_OF_POOLS{32};
	std::mutex mtx;
	std::mutex accu_mtx;
	std::mutex print_mtx;
	std::thread th_gen;
	std::thread th_accu;
	std::thread th_sfm;
	std::thread th_urandom;

	Fortuna();
	~Fortuna() noexcept;

	[[optimize_for_synchronized]] auto random_data(unsigned int) -> void;

	auto set_reseed_ctr_to_null() -> void {
		std::lock_guard<std::mutex> lg(mtx);
		Fortuna::R.null_da_ctr();
	}

	auto incr_reseed_ctr() -> void {
		std::lock_guard<std::mutex> lg(mtx);
		++Fortuna::R.reseed_ctr;
	}

	auto get_reseed_ctr() const -> uint64_t {
		return R.reseed_ctr;
	}

	auto initialize_prng() -> void {
		// TODO(me): handle the reseeds here as per Cryptography Engineering,
		// p. 153
		set_reseed_ctr_to_null();
		std::unique_lock<std::mutex> p_ul(print_mtx);
		std::unique_lock<std::mutex> a_ul(accu_mtx);
		try {
			R.initialize_pools();
			fmt::print("[i] fortuna: pools initialized\n");
			p_ul.unlock();
			accumulator.set_pools_ptr(R._p_pools);
			accumulator.set_gen(R.Gen);
			a_ul.unlock();

			// FIXME: bogus first reseed here, P_0 definitely hasn't collected
			// enough entropy by now
			incr_reseed_ctr();

			p_ul.lock();
			fmt::print("first reseed\n");
			p_ul.unlock();

			std::unique_lock<std::mutex> ul(mtx);
			R.Gen.reseed("fortuna");
			ul.unlock();
		}
		catch (std::exception& e) {
			p_ul.try_lock();
			fmt::print(
				"{}\n[!] fortuna: fatal error, PRNG initialization FAILED!\n\n",
				e.what());
		}
		p_ul.try_lock();
		fmt::print("[*] fortuna: PRNG initialized\n");
	}

	auto generator_service(std::shared_ptr<fortuna::generator::Generator> Gen)
		-> void;

	auto accumulator_service() -> void;

	auto seed_file_manager_service() -> void;

	auto urandom_entropy_src_service() -> void;

	// PRNG state
	class R_state {
		friend fortuna::Fortuna;

	public:
		R_state() noexcept {}
		~R_state() noexcept = default;

	protected:
		auto null_da_ctr() -> void {
			reseed_ctr = 0x00;
			fmt::print("reseed_ctr set to 0x00\n");
		}

		auto initialize_pools() -> void {
			for (unsigned int i = accumulator::Accumulator::init_pool_num;
				 i < Fortuna::NUM_OF_POOLS;
				 ++i) {
				this->_p_pools->at(i).initialize_pool(i);
			}
		}

	private:
		generator::Generator Gen;
		uint64_t reseed_ctr{0x00};

		// da_pools is to be used solely for creating a shared_ptr of the
		// object: _p_pools. any further access to the structure should be
		// facilitated by the subject _p_pools shared_ptr. to convey this,
		// da_pools is declared const
		const std::array<accumulator::Pool, Fortuna::NUM_OF_POOLS> da_pools;

		// _p_pools points to the da_pools array of 32 Pool objects
		std::shared_ptr<std::array<accumulator::Pool, Fortuna::NUM_OF_POOLS>>
			_p_pools{std::make_shared<
				std::array<accumulator::Pool, Fortuna::NUM_OF_POOLS>>()};

		std::chrono::steady_clock::time_point last_reseed;
	}; // class R_state

	fortuna::Fortuna::R_state R;
	fortuna::accumulator::Accumulator accumulator;

}; // class Fortuna

} // namespace fortuna

#endif // FORTUNA_FORTUNA_H