fortuna/pool.cpp

#ifndef FORTUNA_POOL_CPP
#define FORTUNA_POOL_CPP

#include "pool.h"

#include <fmt/core.h>
#include <fmt/ranges.h>

#include <atomic>
#include <climits>
#include <cstddef>
#include <mutex>
#include <stdexcept>
#include <utility>

namespace fortuna {
namespace accumulator {

auto Pool::set_id(const unsigned int& id) noexcept -> void {
	std::lock_guard<std::mutex> lg(mtx);
	this->pool_id = id;
}

auto Pool::get_id() const noexcept -> unsigned int {
	return this->pool_id;
}

auto Pool::initialize_pool(const unsigned int& id) -> void {
	// ref: https://stackoverflow.com/a/23204682
	std::call_once(init, [this, id] { this->set_id(id); });
}

auto Pool::add_entropy(const unsigned int& source,
					   const std::vector<char>& event) -> int {
	std::unique_lock<std::recursive_mutex> ul(ro_mtx_s);
	const size_t event_size{sizeof(char) * event.size()};
	const size_t max_event_size{32};
	std::string event_str;
	std::atomic<bool> all_ok{false};

	fmt::print(stderr, "\tevent_size (bytes): {}\n", event_size);
	try {
		if (source > 255) {
			throw std::invalid_argument(
				"source number outside of interval <0,255>\n");
		}
		fmt::print(stderr, "\tsource_id: {}\n", source);

		if (event_size < 1 || event_size > max_event_size) {
			const std::string msg{
				"[!] add_entropy: the length of the event needs to "
				"be from the interval <1,32>"};
			fmt::print(stderr,
					   "\tsource: {}\n{}\nevent size: {}\n\tpool_id: {}",
					   source,
					   msg,
					   event_size,
					   this->pool_id);
			throw std::invalid_argument(msg);
		}
		else {
			all_ok = true;
		}
	}
	catch (const std::exception& e) {
		fmt::print(stderr, "{}\n", e.what());
		throw;
	}

	if (all_ok) {
		try {
			{
				// FIXME: check for overflow - std::string size bounding?
				// event_str.assign(event.begin(), event.end());

				// as per Cryptography Engineering, p. 148 (180/385)
				std::vector<char> fullevent{static_cast<char>(source)};
				fullevent.push_back(static_cast<char>(event_size));
				fullevent.insert(
					std::end(fullevent), std::begin(event), std::end(event));
				fmt::print(
					stderr, "\t[i] add_entropy(fullevent): {}\n", fullevent);

				// FIXME: check size for overflow
				// also, atm this counts event size but actually what gets
				// appended are digests of 64 characters (hex-encoded 32 bytes)
				size += event_size;

				{
					const std::string digest(fortuna::Util::do_sha(fullevent));

					fmt::print(
						stderr, "\t[i] add_entropy(digest): {}\n", digest);

					append_s(digest);
				}
			}

			fmt::print(stderr,
					   "\t[i] s.length()  (simple char count): {}\n"
					   "\t[i] get_s_byte_count() (byte count): {}\n"
					   "\t[i] pool_id: {}\n"
					   "\t[i] s: {}\n",
					   this->s.length(),
					   this->get_s_byte_count(),
					   this->pool_id,
					   // "");
					   this->s);
		}
		catch (const std::exception& e) {
			fmt::print(stderr, "[!] pool(add_entropy): {}\n", e.what());
			// FIXME: handle this (as all the other unhandled exceptions)
			throw;
		}

		return 0;
	}
	else {
		// everything not ok
		return 1;
	}
} // add_entropy

auto Pool::get_s_byte_count() const -> uint64_t {
	// returns total byte count of (hex-encoded) entropy string contained in
	// the pool. since the string is hex-encoded, we divide its char count by 2
	// to get proper byte count. we need this since we actually don't care about
	// the length of the hex string as it is, rather we care about what it came
	// from (the raw entropy event)

	std::lock_guard<std::recursive_mutex> lg(ro_mtx_s);
	return this->s.length() / 2;
}

auto Pool::get_s() const -> std::string {
	std::lock_guard<std::recursive_mutex> lg(ro_mtx_s);
	return this->s;
}

auto Pool::clear_pool() -> void {
	std::lock_guard<std::mutex> lg(mtx);
	this->s.clear();
}

auto Pool::append_s(const std::string& entropy_s) -> void {
	std::lock_guard<std::mutex> lg(mtx);
	try {
		this->s.append(entropy_s);
	}
	catch (const std::exception& e) {
		fmt::print(stderr, "{}\n", e.what());
	}
}


} // namespace accumulator
} // namespace fortuna

#endif // FORTUNA_POOL_CPP