datagram-transport.hpp

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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/>.
 */
 
#ifndef NFD_DAEMON_FACE_DATAGRAM_TRANSPORT_HPP
#define NFD_DAEMON_FACE_DATAGRAM_TRANSPORT_HPP
 
#include "transport.hpp"
#include "socket-utils.hpp"
#include "common/global.hpp"
 
#include <array>
 
namespace nfd::face {
 
struct Unicast {};
struct Multicast {};
 
template<class Protocol, class Addressing>
class DatagramTransport : public Transport
{
public:
  using protocol = Protocol;
  using addressing = Addressing;
 
  explicit
  DatagramTransport(typename protocol::socket&& socket);
 
  ssize_t
  getSendQueueLength() override;
 
  void
  receiveDatagram(span<const uint8_t> buffer, const boost::system::error_code& error);
 
protected:
  void
  doClose() override;
 
  void
  doSend(const Block& packet) override;
 
  void
  handleSend(const boost::system::error_code& error, size_t nBytesSent);
 
  void
  handleReceive(const boost::system::error_code& error, size_t nBytesReceived);
 
  void
  processErrorCode(const boost::system::error_code& error);
 
  bool
  hasRecentlyReceived() const;
 
  void
  resetRecentlyReceived();
 
protected:
  typename protocol::socket m_socket;
  typename protocol::endpoint m_sender;
 
  NFD_LOG_MEMBER_DECL();
 
private:
  std::array<uint8_t, ndn::MAX_NDN_PACKET_SIZE> m_receiveBuffer;
  bool m_hasRecentlyReceived;
};
 
 
template<class T, class U>
DatagramTransport<T, U>::DatagramTransport(typename DatagramTransport::protocol::socket&& socket)
  : m_socket(std::move(socket))
  , m_hasRecentlyReceived(false)
{
  boost::asio::socket_base::send_buffer_size sendBufferSizeOption;
  boost::system::error_code error;
  m_socket.get_option(sendBufferSizeOption, error);
  if (error) {
    NFD_LOG_FACE_WARN("Failed to obtain send queue capacity from socket: " << error.message());
    this->setSendQueueCapacity(QUEUE_ERROR);
  }
  else {
    this->setSendQueueCapacity(sendBufferSizeOption.value());
  }
 
  m_socket.async_receive_from(boost::asio::buffer(m_receiveBuffer), m_sender,
                              [this] (auto&&... args) {
                                this->handleReceive(std::forward<decltype(args)>(args)...);
                              });
}
 
template<class T, class U>
ssize_t
DatagramTransport<T, U>::getSendQueueLength()
{
  ssize_t queueLength = getTxQueueLength(m_socket.native_handle());
  if (queueLength == QUEUE_ERROR) {
    NFD_LOG_FACE_WARN("Failed to obtain send queue length from socket: " << std::strerror(errno));
  }
  return queueLength;
}
 
template<class T, class U>
void
DatagramTransport<T, U>::doClose()
{
  NFD_LOG_FACE_TRACE(__func__);
 
  if (m_socket.is_open()) {
    // Cancel all outstanding operations and close the socket.
    // Use the non-throwing variants and ignore errors, if any.
    boost::system::error_code error;
    m_socket.cancel(error);
    m_socket.close(error);
  }
 
  // Ensure that the Transport stays alive at least until
  // all pending handlers are dispatched
  getGlobalIoService().post([this] {
    this->setState(TransportState::CLOSED);
  });
}
 
template<class T, class U>
void
DatagramTransport<T, U>::doSend(const Block& packet)
{
  NFD_LOG_FACE_TRACE(__func__);
 
  m_socket.async_send(boost::asio::buffer(packet),
                      // 'packet' is copied into the lambda to retain the underlying Buffer
                      [this, packet] (auto&&... args) {
                        this->handleSend(std::forward<decltype(args)>(args)...);
                      });
}
 
template<class T, class U>
void
DatagramTransport<T, U>::receiveDatagram(span<const uint8_t> buffer,
                                         const boost::system::error_code& error)
{
  if (error)
    return processErrorCode(error);
 
  NFD_LOG_FACE_TRACE("Received: " << buffer.size() << " bytes from " << m_sender);
 
  auto [isOk, element] = Block::fromBuffer(buffer);
  if (!isOk) {
    NFD_LOG_FACE_WARN("Failed to parse incoming packet from " << m_sender);
    // This packet won't extend the face lifetime
    return;
  }
  if (element.size() != buffer.size()) {
    NFD_LOG_FACE_WARN("Received datagram size and decoded element size don't match");
    // This packet won't extend the face lifetime
    return;
  }
  m_hasRecentlyReceived = true;
 
  if constexpr (std::is_same_v<addressing, Multicast>)
    this->receive(element, m_sender);
  else
    this->receive(element);
}
 
template<class T, class U>
void
DatagramTransport<T, U>::handleReceive(const boost::system::error_code& error, size_t nBytesReceived)
{
  receiveDatagram(ndn::make_span(m_receiveBuffer).first(nBytesReceived), error);
 
  if (m_socket.is_open())
    m_socket.async_receive_from(boost::asio::buffer(m_receiveBuffer), m_sender,
                                [this] (auto&&... args) {
                                  this->handleReceive(std::forward<decltype(args)>(args)...);
                                });
}
 
template<class T, class U>
void
DatagramTransport<T, U>::handleSend(const boost::system::error_code& error, size_t nBytesSent)
{
  if (error)
    return processErrorCode(error);
 
  NFD_LOG_FACE_TRACE("Successfully sent: " << nBytesSent << " bytes");
}
 
template<class T, class U>
void
DatagramTransport<T, U>::processErrorCode(const boost::system::error_code& error)
{
  NFD_LOG_FACE_TRACE(__func__);
 
  if (getState() == TransportState::CLOSING ||
      getState() == TransportState::FAILED ||
      getState() == TransportState::CLOSED ||
      error == boost::asio::error::operation_aborted) {
    // transport is shutting down, ignore any errors
    return;
  }
 
  if (getPersistency() == ndn::nfd::FACE_PERSISTENCY_PERMANENT) {
    NFD_LOG_FACE_DEBUG("Permanent face ignores error: " << error.message());
    return;
  }
 
  NFD_LOG_FACE_ERROR("Send or receive operation failed: " << error.message());
  this->setState(TransportState::FAILED);
  doClose();
}
 
template<class T, class U>
bool
DatagramTransport<T, U>::hasRecentlyReceived() const
{
  return m_hasRecentlyReceived;
}
 
template<class T, class U>
void
DatagramTransport<T, U>::resetRecentlyReceived()
{
  m_hasRecentlyReceived = false;
}
 
} // namespace nfd::face
 
#endif // NFD_DAEMON_FACE_DATAGRAM_TRANSPORT_HPP