com.groupbyinc.common.apache.commons.net.tftp.TFTPAckPacket Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.net.tftp;
import java.net.DatagramPacket;
import java.net.InetAddress;
/***
* A final class derived from TFTPPacket definiing the TFTP Acknowledgement
* packet type.
*
* Details regarding the TFTP protocol and the format of TFTP packets can
* be found in RFC 783. But the point of these classes is to keep you
* from having to worry about the internals. Additionally, only very
* few people should have to care about any of the TFTPPacket classes
* or derived classes. Almost all users should only be concerned with the
* {@link org.apache.commons.net.tftp.TFTPClient} class
* {@link org.apache.commons.net.tftp.TFTPClient#receiveFile receiveFile()}
* and
* {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()}
* methods.
*
*
* @see TFTPPacket
* @see TFTPPacketException
* @see TFTP
***/
public final class TFTPAckPacket extends TFTPPacket
{
/*** The block number being acknowledged by the packet. ***/
int _blockNumber;
/***
* Creates an acknowledgment packet to be sent to a host at a given port
* acknowledging receipt of a block.
*
* @param destination The host to which the packet is going to be sent.
* @param port The port to which the packet is going to be sent.
* @param blockNumber The block number being acknowledged.
***/
public TFTPAckPacket(InetAddress destination, int port, int blockNumber)
{
super(TFTPPacket.ACKNOWLEDGEMENT, destination, port);
_blockNumber = blockNumber;
}
/***
* Creates an acknowledgement packet based from a received
* datagram. Assumes the datagram is at least length 4, else an
* ArrayIndexOutOfBoundsException may be thrown.
*
* @param datagram The datagram containing the received acknowledgement.
* @throws TFTPPacketException If the datagram isn't a valid TFTP
* acknowledgement packet.
***/
TFTPAckPacket(DatagramPacket datagram) throws TFTPPacketException
{
super(TFTPPacket.ACKNOWLEDGEMENT, datagram.getAddress(),
datagram.getPort());
byte[] data;
data = datagram.getData();
if (getType() != data[1]) {
throw new TFTPPacketException("TFTP operator code does not match type.");
}
_blockNumber = (((data[2] & 0xff) << 8) | (data[3] & 0xff));
}
/***
* This is a method only available within the package for
* implementing efficient datagram transport by elminating buffering.
* It takes a datagram as an argument, and a byte buffer in which
* to store the raw datagram data. Inside the method, the data
* is set as the datagram's data and the datagram returned.
*
* @param datagram The datagram to create.
* @param data The buffer to store the packet and to use in the datagram.
* @return The datagram argument.
***/
@Override
DatagramPacket _newDatagram(DatagramPacket datagram, byte[] data)
{
data[0] = 0;
data[1] = (byte)_type;
data[2] = (byte)((_blockNumber & 0xffff) >> 8);
data[3] = (byte)(_blockNumber & 0xff);
datagram.setAddress(_address);
datagram.setPort(_port);
datagram.setData(data);
datagram.setLength(4);
return datagram;
}
/***
* Creates a UDP datagram containing all the TFTP
* acknowledgement packet data in the proper format.
* This is a method exposed to the programmer in case he
* wants to implement his own TFTP client instead of using
* the {@link org.apache.commons.net.tftp.TFTPClient}
* class. Under normal circumstances, you should not have a need to call this
* method.
*
* @return A UDP datagram containing the TFTP acknowledgement packet.
***/
@Override
public DatagramPacket newDatagram()
{
byte[] data;
data = new byte[4];
data[0] = 0;
data[1] = (byte)_type;
data[2] = (byte)((_blockNumber & 0xffff) >> 8);
data[3] = (byte)(_blockNumber & 0xff);
return new DatagramPacket(data, data.length, _address, _port);
}
/***
* Returns the block number of the acknowledgement.
*
* @return The block number of the acknowledgement.
***/
public int getBlockNumber()
{
return _blockNumber;
}
/***
* Sets the block number of the acknowledgement.
*
* @param blockNumber the number to set
***/
public void setBlockNumber(int blockNumber)
{
_blockNumber = blockNumber;
}
}