transmission/libtransmission/port-forwarding-natpmp.h

// This file Copyright © Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.

#pragma once

#ifndef LIBTRANSMISSION_PORT_FORWARDING_MODULE
#error only the libtransmission port forwarding module should #include this header.
#endif

#include <ctime> // time_t
#include <cstdint>

#include "natpmp.h"

#include "libtransmission/transmission.h" // tr_port_forwarding_state

#include "libtransmission/net.h" // tr_port

class tr_natpmp
{
public:
    tr_natpmp()
    {
        natpmp_.s = static_cast<decltype(natpmp_.s)>(TR_BAD_SOCKET);
    }

    ~tr_natpmp()
    {
        closenatpmp(&natpmp_);
    }

    [[nodiscard]] constexpr auto renewTime() const noexcept
    {
        return renew_time_;
    }

    struct PulseResult
    {
        tr_port_forwarding_state state = TR_PORT_ERROR;

        tr_port local_port;
        tr_port advertised_port;
    };

    PulseResult pulse(tr_port local_port, bool is_enabled);

private:
    enum class State
    {
        Idle,
        Err,
        Discover,
        RecvPub,
        SendMap,
        RecvMap,
        SendUnmap,
        RecvUnmap
    };

    static constexpr auto LifetimeSecs = uint32_t{ 3600 };
    static constexpr auto CommandWaitSecs = time_t{ 8 };

    [[nodiscard]] bool canSendCommand() const;

    void setCommandTime();

    natpmp_t natpmp_ = {};

    tr_port local_port_;
    tr_port advertised_port_;

    time_t renew_time_ = 0;
    time_t command_time_ = 0;
    State state_ = State::Discover;

    bool has_discovered_ = false;
    bool is_mapped_ = false;
};