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fortuna/urandom_entropy_src.h
surtur d404681889
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feat: "prepare to add proper entropy source" nits
general
* make greater use of "this"

Fortuna
* declare da_pools as a proper std::array of 32 Pool objects
* declare da_pools as const
* use std::shared_ptr _p_pools to access da_pools and share access to
  it
* reflect change of pools[] -> std::array in how the array elements
  are accessed, which is a) via _p_pools pointer and b) using ".at(i)"
  function
* pass _p_pools shared_ptr to Accumulator
* refactor member function names and variable names
* add member function attribute [[optimize_for_synchronized]]
* secure conversions with static_cast-s

Accumulator
* make use of _p_pools
* add _p_pools-related member functions
* add a static constexpr variable NUM_OF_POOLS

UrandomEntropySrc
* implement event adding logic using _p_pools
* make std::vector<char> non-static in urandom_entropy_src
* implement proper urandom entropy source event "sourcing" (from
  /dev/urandom), event adding, clear bytes array at the end
* properly convert using reinterpret_cast
* protect access to the main function with std::lock_guard
* receive EventAdderImpl as a ref
* use return value from "add_entropy()" member function and create
  sanity guard checking the return code "int ret"

EventAdder
* pass event (std::vector<char>) by const&

EventAdderImpl
* make use of _p_pools shared_ptr
* implement proper pool-rotating event-adding logic

Pool
* delete all copy constructors and assignment operator, the objects
  will not be copied or assigned to
* receive parameters by const& where possible/sensible
* handle concurrency:
  * declare std:string s as mutable
  * declare a rw std::mutex intended for writing and mutable
    std::recursive_mutex for read-only operations in const member
    functions
    ref: https://herbsutter.com/2013/05/24/gotw-6a-const-correctness-part-1-3/
    ref: https://arne-mertz.de/2017/10/mutable/
  * use std::lock_guard and std::unique_lock
* refactor "add_entropy()" member function
  * get rid of intermediate "event_str" and directly use the "event"
    std::vector<char> for all operations
  * add a lock guard to prevent multiple threads (should that route be
    taken) from modifying pool resources simultaneously
  * add all_ok bool for basic sanity checking
  * add print statements (at least for now)
* rename "get_s_length()" member function to "get_s_byte_count()" and
  repurpose it to return byte count of the stored entropy std::string s
2022-01-17 08:27:24 +01:00

35 lines
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C++

#ifndef FORTUNA_URANDOM_ENTROPY_SRC_H
#define FORTUNA_URANDOM_ENTROPY_SRC_H
#include "entropy_src.h"
#include "event_adder_impl.h"
#include <fmt/core.h>
#include <cstddef>
#include <cstdint>
#include <fstream>
#include <mutex>
#include <vector>
namespace fortuna {
namespace accumulator {
class UrandomEntropySrc : public EntropySrc {
private:
std::vector<char> bytes{0};
std::mutex mtx;
public:
auto event(accumulator::EventAdderImpl& adder) -> void;
auto urandom_entropy_src_service() -> int;
UrandomEntropySrc();
~UrandomEntropySrc() noexcept;
};
} // namespace accumulator
} // namespace fortuna
#endif // FORTUNA_URANDOM_ENTROPY_SRC_H