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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
* Copyright (c) 2014-2022, Regents of the University of California,
* Arizona Board of Regents,
* Colorado State University,
* University Pierre & Marie Curie, Sorbonne University,
* Washington University in St. Louis,
* Beijing Institute of Technology,
* The University of Memphis.
*
* This file is part of NFD (Named Data Networking Forwarding Daemon).
* See AUTHORS.md for complete list of NFD authors and contributors.
*
* NFD is free software: you can redistribute it and/or modify it under the terms
* of the GNU General Public License as published by the Free Software Foundation,
* either version 3 of the License, or (at your option) any later version.
*
* NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
* without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along with
* NFD, e.g., in COPYING.md file. If not, see <http://www.gnu.org/licenses/>.
*/
#include "unicast-udp-transport.hpp"
#include "udp-protocol.hpp"
#include "common/global.hpp"
#ifdef __linux__
#include <cerrno> // for errno
#include <cstring> // for std::strerror()
#include <netinet/in.h> // for IP_MTU_DISCOVER and IP_PMTUDISC_DONT
#include <sys/socket.h> // for setsockopt()
#endif
namespace nfd::face {
NFD_LOG_MEMBER_INIT_SPECIALIZED((DatagramTransport<boost::asio::ip::udp, Unicast>), UnicastUdpTransport);
UnicastUdpTransport::UnicastUdpTransport(protocol::socket&& socket,
ndn::nfd::FacePersistency persistency,
time::nanoseconds idleTimeout)
: DatagramTransport(std::move(socket))
, m_idleTimeout(idleTimeout)
{
this->setLocalUri(FaceUri(m_socket.local_endpoint()));
this->setRemoteUri(FaceUri(m_socket.remote_endpoint()));
this->setScope(ndn::nfd::FACE_SCOPE_NON_LOCAL);
this->setPersistency(persistency);
this->setLinkType(ndn::nfd::LINK_TYPE_POINT_TO_POINT);
this->setMtu(udp::computeMtu(m_socket.local_endpoint()));
NFD_LOG_FACE_DEBUG("Creating transport");
#ifdef __linux__
//
// By default, Linux does path MTU discovery on IPv4 sockets,
// and sets the DF (Don't Fragment) flag on datagrams smaller
// than the interface MTU. However this does not work for us,
// because we cannot properly respond to ICMP "packet too big"
// messages by fragmenting the packet at the application level,
// since we want to rely on IP for fragmentation and reassembly.
//
// Therefore, we disable PMTU discovery, which prevents the kernel
// from setting the DF flag on outgoing datagrams, and thus allows
// routers along the path to perform fragmentation as needed.
//
const int value = IP_PMTUDISC_DONT;
if (::setsockopt(m_socket.native_handle(), IPPROTO_IP,
IP_MTU_DISCOVER, &value, sizeof(value)) < 0) {
NFD_LOG_FACE_WARN("Failed to disable path MTU discovery: " << std::strerror(errno));
}
#endif
if (getPersistency() == ndn::nfd::FACE_PERSISTENCY_ON_DEMAND &&
m_idleTimeout > time::nanoseconds::zero()) {
scheduleClosureWhenIdle();
}
}
bool
UnicastUdpTransport::canChangePersistencyToImpl(ndn::nfd::FacePersistency newPersistency) const
{
return true;
}
void
UnicastUdpTransport::afterChangePersistency(ndn::nfd::FacePersistency oldPersistency)
{
if (getPersistency() == ndn::nfd::FACE_PERSISTENCY_ON_DEMAND &&
m_idleTimeout > time::nanoseconds::zero()) {
scheduleClosureWhenIdle();
}
else {
m_closeIfIdleEvent.cancel();
setExpirationTime(time::steady_clock::time_point::max());
}
}
void
UnicastUdpTransport::scheduleClosureWhenIdle()
{
m_closeIfIdleEvent = getScheduler().schedule(m_idleTimeout, [this] {
if (!hasRecentlyReceived()) {
NFD_LOG_FACE_INFO("Closing due to inactivity");
this->close();
}
else {
resetRecentlyReceived();
scheduleClosureWhenIdle();
}
});
setExpirationTime(time::steady_clock::now() + m_idleTimeout);
}
} // namespace nfd::face