/**
* Copyright (C) 2014-2017 Regents of the University of California.
* @author: Jeff Thompson <jefft0@remap.ucla.edu>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
* A copy of the GNU Lesser General Public License is in the file COPYING.
*/
package net.named_data.jndn.transport;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import net.named_data.jndn.encoding.ElementListener;
import net.named_data.jndn.encoding.ElementReader;
import net.named_data.jndn.encoding.EncodingException;
import net.named_data.jndn.util.Common;
/**
* UdpTransport extends the Transport interface to implement communication over
* UDP.
*/
public class UdpTransport extends Transport {
/**
* A UdpTransport.ConnectionInfo extends Transport.ConnectionInfo to hold
* the host and port info for the UDP connection.
*/
public static class ConnectionInfo extends Transport.ConnectionInfo {
/**
* Create a ConnectionInfo with the given host and port.
* @param host The host for the connection.
* @param port The port number for the connection.
*/
public
ConnectionInfo(String host, int port)
{
host_ = host;
port_ = port;
}
/**
* Create a ConnectionInfo with the given host and default port 6363.
* @param host The host for the connection.
*/
public
ConnectionInfo(String host)
{
host_ = host;
port_ = 6363;
}
/**
* Get the host given to the constructor.
* @return The host.
*/
public final String
getHost() { return host_; }
/**
* Get the port given to the constructor.
* @return The port number.
*/
public final int
getPort() { return port_; }
private final String host_;
private final int port_;
}
/**
* Determine whether this transport connecting according to connectionInfo is
* to a node on the current machine. According to
* http://redmine.named-data.net/issues/2532#note-8, UDP transports are always
* non-local.
* @param connectionInfo This is ignored.
* @return False because UDP transports are always non-local.
*/
public boolean isLocal(Transport.ConnectionInfo connectionInfo) {
return false;
}
/**
* Override to return false since connect does not need to use the onConnected
* callback.
* @return False.
*/
public boolean
isAsync() { return false; }
/**
* Connect according to the info in ConnectionInfo, and use elementListener.
* @param connectionInfo A UdpTransport.ConnectionInfo.
* @param elementListener The ElementListener must remain valid during the
* life of this object.
* @param onConnected If not null, this calls onConnected.run() when the
* connection is established.
* @throws IOException For I/O error.
*/
public void
connect
(Transport.ConnectionInfo connectionInfo, ElementListener elementListener,
Runnable onConnected)
throws IOException
{
close();
channel_ = DatagramChannel.open();
channel_.connect(new InetSocketAddress
(((ConnectionInfo)connectionInfo).getHost(),
((ConnectionInfo)connectionInfo).getPort()));
channel_.configureBlocking(false);
elementReader_ = new ElementReader(elementListener);
if (onConnected != null)
onConnected.run();
}
/**
* Send data to the host
* @param data The buffer of data to send. This reads from position() to
* limit(), but does not change the position.
* @throws IOException For I/O error.
*/
public void
send(ByteBuffer data) throws IOException
{
if (channel_ == null)
throw new IOException
("Cannot send because the socket is not open. Use connect.");
// Save and restore the position.
int savePosition = data.position();
try {
while(data.hasRemaining())
channel_.write(data);
}
finally {
data.position(savePosition);
}
}
/**
* Process any data to receive. For each element received, call
* elementListener.onReceivedElement.
* This is non-blocking and will return immediately if there is no data to
* receive. You should normally not call this directly since it is called by
* Face.processEvents.
* If you call this from an main event loop, you may want to catch and
* log/disregard all exceptions.
* @throws IOException For I/O error.
* @throws EncodingException For invalid encoding.
*/
public void
processEvents() throws IOException, EncodingException
{
if (!getIsConnected())
return;
while (true) {
inputBuffer_.limit(inputBuffer_.capacity());
inputBuffer_.position(0);
int bytesRead = channel_.read(inputBuffer_);
if (bytesRead <= 0)
return;
inputBuffer_.flip();
elementReader_.onReceivedData(inputBuffer_);
}
}
/**
* Check if the transport is connected.
* @return True if connected.
*/
public boolean
getIsConnected() throws IOException
{
if (channel_ == null)
return false;
return channel_.isConnected();
}
/**
* Close the connection. If not connected, this does nothing.
* @throws IOException For I/O error.
*/
public void
close() throws IOException
{
if (channel_ != null) {
if (channel_.isConnected())
channel_.close();
channel_ = null;
}
}
DatagramChannel channel_;
ByteBuffer inputBuffer_ = ByteBuffer.allocate(Common.MAX_NDN_PACKET_SIZE);
// TODO: This belongs in the socket listener.
private ElementReader elementReader_;
}