transmission/libtransmission/port-forwarding.cc

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// This file Copyright © 2008-2023 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.
#include <algorithm>
#include <chrono>
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#include <memory>
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#include <fmt/core.h>
#define LIBTRANSMISSION_PORT_FORWARDING_MODULE
#include "libtransmission/transmission.h"
#include "libtransmission/log.h"
#include "libtransmission/net.h"
#include "libtransmission/port-forwarding-natpmp.h"
#include "libtransmission/port-forwarding-upnp.h"
#include "libtransmission/port-forwarding.h"
#include "libtransmission/timer.h"
#include "libtransmission/torrent.h"
#include "libtransmission/tr-assert.h"
#include "libtransmission/utils.h" // for _()
using namespace std::literals;
class tr_port_forwarding_impl final : public tr_port_forwarding
{
public:
explicit tr_port_forwarding_impl(Mediator& mediator)
: mediator_{ mediator }
{
}
~tr_port_forwarding_impl() override
{
is_shutting_down_ = true;
stopForwarding();
}
tr_port_forwarding_impl(tr_port_forwarding_impl&&) = delete;
tr_port_forwarding_impl(tr_port_forwarding_impl const&) = delete;
tr_port_forwarding_impl& operator=(tr_port_forwarding_impl&&) = delete;
tr_port_forwarding_impl& operator=(tr_port_forwarding_impl const&) = delete;
void local_port_changed() override
{
if (!is_enabled_)
{
return;
}
stopTimer();
natPulse(false);
startTimer();
}
void set_enabled(bool enabled) override
{
if (enabled)
{
is_enabled_ = true;
startTimer();
}
else
{
is_enabled_ = false;
stopForwarding();
}
}
[[nodiscard]] bool is_enabled() const noexcept override
{
return is_enabled_;
}
[[nodiscard]] tr_port_forwarding_state state() const noexcept override
{
return std::max(natpmp_state_, upnp_state_);
}
private:
void stopTimer()
{
timer_.reset();
}
void stopForwarding()
{
tr_logAddTrace("stopped");
natPulse(false);
natpmp_.reset();
natpmp_state_ = TR_PORT_UNMAPPED;
tr_upnpClose(upnp_);
upnp_ = nullptr;
upnp_state_ = TR_PORT_UNMAPPED;
stopTimer();
}
void startTimer()
{
timer_ = mediator_.timer_maker().create([this]() { this->onTimer(); });
restartTimer();
}
void restartTimer()
{
if (!timer_)
{
return;
}
// when to wake up again
switch (state())
{
case TR_PORT_MAPPED:
// if we're mapped, everything is fine... check back at `renew_time`
// to renew the port forwarding if it's expired
do_port_check_ = true;
if (auto const now = tr_time(); natpmp_->renewTime() > now)
{
timer_->start_single_shot(std::chrono::seconds{ natpmp_->renewTime() - now });
}
else // ???
{
timer_->start_single_shot(1min);
}
break;
case TR_PORT_ERROR:
// some kind of an error. wait a minute and retry
timer_->start_single_shot(1min);
break;
default:
// in progress. pulse frequently.
timer_->start_single_shot(333ms);
break;
}
}
void onTimer()
{
TR_ASSERT(timer_);
// do something
natPulse(do_port_check_);
do_port_check_ = false;
// set up the timer for the next pulse
restartTimer();
}
static constexpr char const* getNatStateStr(int state)
{
switch (state)
{
case TR_PORT_MAPPING:
return _("Starting");
case TR_PORT_MAPPED:
return _("Forwarded");
case TR_PORT_UNMAPPING:
return _("Stopping");
case TR_PORT_UNMAPPED:
return _("Not forwarded");
default:
return "???";
}
}
void natPulse(bool do_check)
{
auto const is_enabled = is_enabled_ && !is_shutting_down_;
if (!natpmp_)
{
natpmp_ = std::make_unique<tr_natpmp>();
}
if (upnp_ == nullptr)
{
upnp_ = tr_upnpInit();
}
auto const old_state = state();
auto const result = natpmp_->pulse(mediator_.local_peer_port(), is_enabled);
natpmp_state_ = result.state;
if (!std::empty(result.local_port) && !std::empty(result.advertised_port))
{
mediator_.on_port_forwarded(result.advertised_port);
tr_logAddInfo(fmt::format(
_("Mapped private port {private_port} to public port {public_port}"),
fmt::arg("private_port", result.local_port.host()),
fmt::arg("public_port", result.advertised_port.host())));
}
upnp_state_ = tr_upnpPulse(
upnp_,
mediator_.local_peer_port(),
is_enabled,
do_check,
mediator_.incoming_peer_address().display_name());
if (auto const new_state = state(); new_state != old_state)
{
tr_logAddInfo(fmt::format(
_("State changed from '{old_state}' to '{state}'"),
fmt::arg("old_state", getNatStateStr(old_state)),
fmt::arg("state", getNatStateStr(new_state))));
}
}
Mediator& mediator_;
bool is_enabled_ = false;
bool is_shutting_down_ = false;
bool do_port_check_ = false;
tr_port_forwarding_state natpmp_state_ = TR_PORT_UNMAPPED;
tr_port_forwarding_state upnp_state_ = TR_PORT_UNMAPPED;
tr_upnp* upnp_ = nullptr;
std::unique_ptr<tr_natpmp> natpmp_;
std::unique_ptr<libtransmission::Timer> timer_;
};
std::unique_ptr<tr_port_forwarding> tr_port_forwarding::create(Mediator& mediator)
{
return std::make_unique<tr_port_forwarding_impl>(mediator);
}