transmission/libtransmission/port-forwarding-natpmp.cc

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// 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.
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#include <array>
#include <cerrno>
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#ifdef _WIN32
#include <ws2tcpip.h>
#else
#include <sys/socket.h> // AF_INET
#endif
#include <event2/util.h> /* evutil_inet_ntop() */
#include <fmt/core.h>
#define ENABLE_STRNATPMPERR
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#include "natpmp.h"
#define LIBTRANSMISSION_PORT_FORWARDING_MODULE
#include "libtransmission/transmission.h"
#include "libtransmission/log.h"
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#include "libtransmission/net.h"
#include "libtransmission/port-forwarding-natpmp.h"
#include "libtransmission/utils.h"
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namespace
{
void log_val(char const* func, int ret)
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{
if (ret == NATPMP_TRYAGAIN)
{
return;
}
if (ret >= 0)
{
tr_logAddDebug(fmt::format("{} succeeded ({})", func, ret));
}
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else
{
tr_logAddDebug(fmt::format(
"{} failed. Natpmp returned {} ({}); errno is {} ({})",
func,
ret,
strnatpmperr(ret),
errno,
tr_strerror(errno)));
}
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}
} // namespace
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bool tr_natpmp::canSendCommand() const
{
return tr_time() >= command_time_;
}
void tr_natpmp::setCommandTime()
{
command_time_ = tr_time() + CommandWaitSecs;
}
tr_natpmp::PulseResult tr_natpmp::pulse(tr_port local_port, bool is_enabled)
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{
if (is_enabled && state_ == State::Discover)
{
int val = initnatpmp(&natpmp_, 0, 0);
log_val("initnatpmp", val);
val = sendpublicaddressrequest(&natpmp_);
log_val("sendpublicaddressrequest", val);
state_ = val < 0 ? State::Err : State::RecvPub;
has_discovered_ = true;
setCommandTime();
}
if (state_ == State::RecvPub && canSendCommand())
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{
natpmpresp_t response;
auto const val = readnatpmpresponseorretry(&natpmp_, &response);
log_val("readnatpmpresponseorretry", val);
if (val >= 0)
{
auto str = std::array<char, 128>{};
evutil_inet_ntop(AF_INET, &response.pnu.publicaddress.addr, std::data(str), std::size(str));
tr_logAddInfo(fmt::format(_("Found public address '{address}'"), fmt::arg("address", std::data(str))));
state_ = State::Idle;
}
else if (val != NATPMP_TRYAGAIN)
{
state_ = State::Err;
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}
}
if ((state_ == State::Idle || state_ == State::Err) && is_mapped_ && (!is_enabled || local_port_ != local_port))
{
state_ = State::SendUnmap;
}
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if (state_ == State::SendUnmap && canSendCommand())
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{
auto const val = sendnewportmappingrequest(
&natpmp_,
NATPMP_PROTOCOL_TCP,
local_port_.host(),
advertised_port_.host(),
0);
log_val("sendnewportmappingrequest", val);
state_ = val < 0 ? State::Err : State::RecvUnmap;
setCommandTime();
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}
if (state_ == State::RecvUnmap)
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{
auto resp = natpmpresp_t{};
auto const val = readnatpmpresponseorretry(&natpmp_, &resp);
log_val("readnatpmpresponseorretry", val);
if (val >= 0)
{
auto const unmapped_port = tr_port::from_host(resp.pnu.newportmapping.privateport);
tr_logAddInfo(fmt::format(_("Port {port} is no longer forwarded"), fmt::arg("port", unmapped_port.host())));
if (local_port_ == unmapped_port)
{
local_port_.clear();
advertised_port_.clear();
state_ = State::Idle;
is_mapped_ = false;
}
}
else if (val != NATPMP_TRYAGAIN)
{
state_ = State::Err;
}
}
if (state_ == State::Idle)
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{
if (is_enabled && !is_mapped_ && has_discovered_)
{
state_ = State::SendMap;
}
else if (is_mapped_ && tr_time() >= renew_time_)
{
state_ = State::SendMap;
}
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}
if (state_ == State::SendMap && canSendCommand())
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{
auto const val = sendnewportmappingrequest(
&natpmp_,
NATPMP_PROTOCOL_TCP,
local_port.host(),
local_port.host(),
LifetimeSecs);
log_val("sendnewportmappingrequest", val);
state_ = val < 0 ? State::Err : State::RecvMap;
setCommandTime();
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}
if (state_ == State::RecvMap)
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{
auto resp = natpmpresp_t{};
auto const val = readnatpmpresponseorretry(&natpmp_, &resp);
log_val("readnatpmpresponseorretry", val);
if (val >= 0)
{
state_ = State::Idle;
is_mapped_ = true;
renew_time_ = tr_time() + (resp.pnu.newportmapping.lifetime / 2);
local_port_ = tr_port::from_host(resp.pnu.newportmapping.privateport);
advertised_port_ = tr_port::from_host(resp.pnu.newportmapping.mappedpublicport);
tr_logAddInfo(fmt::format(_("Port {port} forwarded successfully"), fmt::arg("port", local_port_.host())));
}
else if (val != NATPMP_TRYAGAIN)
{
state_ = State::Err;
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}
}
switch (state_)
{
case State::Idle:
return { is_mapped_ ? TR_PORT_MAPPED : TR_PORT_UNMAPPED, local_port_, advertised_port_ };
case State::Discover:
return { TR_PORT_UNMAPPED, {}, {} };
case State::RecvPub:
case State::SendMap:
case State::RecvMap:
return { TR_PORT_MAPPING, {}, {} };
case State::SendUnmap:
case State::RecvUnmap:
return { TR_PORT_UNMAPPING, {}, {} };
default:
return { TR_PORT_ERROR, {}, {} };
}
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}