/*
* 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 Data
* packet type.
* <p>
* 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.
* <p>
* <p>
* @author Daniel F. Savarese
* @see TFTPPacket
* @see TFTPPacketException
* @see TFTP
***/
public final class TFTPDataPacket extends TFTPPacket
{
/*** The maximum number of bytes in a TFTP data packet (512) ***/
public static final int MAX_DATA_LENGTH = 512;
/*** The minimum number of bytes in a TFTP data packet (0) ***/
public static final int MIN_DATA_LENGTH = 0;
/*** The block number of the packet. ***/
int _blockNumber;
/*** The length of the data. ***/
int _length;
/*** The offset into the _data array at which the data begins. ***/
int _offset;
/*** The data stored in the packet. ***/
byte[] _data;
/***
* Creates a data packet to be sent to a host at a given port
* with a given block number. The actual data to be sent is passed as
* an array, an offset, and a length. The offset is the offset into
* the byte array where the data starts. The length is the length of
* the data. If the length is greater than MAX_DATA_LENGTH, it is
* truncated.
* <p>
* @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 of the data.
* @param data The byte array containing the data.
* @param offset The offset into the array where the data starts.
* @param length The length of the data.
***/
public TFTPDataPacket(InetAddress destination, int port, int blockNumber,
byte[] data, int offset, int length)
{
super(TFTPPacket.DATA, destination, port);
_blockNumber = blockNumber;
_data = data;
_offset = offset;
if (length > MAX_DATA_LENGTH)
_length = MAX_DATA_LENGTH;
else
_length = length;
}
public TFTPDataPacket(InetAddress destination, int port, int blockNumber,
byte[] data)
{
this(destination, port, blockNumber, data, 0, data.length);
}
/***
* Creates a data packet based from a received
* datagram. Assumes the datagram is at least length 4, else an
* ArrayIndexOutOfBoundsException may be thrown.
* <p>
* @param datagram The datagram containing the received data.
* @throws TFTPPacketException If the datagram isn't a valid TFTP
* data packet.
***/
TFTPDataPacket(DatagramPacket datagram) throws TFTPPacketException
{
super(TFTPPacket.DATA, datagram.getAddress(), datagram.getPort());
_data = datagram.getData();
_offset = 4;
if (getType() != _data[1])
throw new TFTPPacketException("TFTP operator code does not match type.");
_blockNumber = (((_data[2] & 0xff) << 8) | (_data[3] & 0xff));
_length = datagram.getLength() - 4;
if (_length > MAX_DATA_LENGTH)
_length = MAX_DATA_LENGTH;
}
/***
* 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.
* <p>
* @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);
// Doublecheck we're not the same
if (data != _data)
System.arraycopy(_data, _offset, data, 4, _length);
datagram.setAddress(_address);
datagram.setPort(_port);
datagram.setData(data);
datagram.setLength(_length + 4);
return datagram;
}
/***
* Creates a UDP datagram containing all the TFTP
* data 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.
* <p>
* @return A UDP datagram containing the TFTP data packet.
***/
@Override
public DatagramPacket newDatagram()
{
byte[] data;
data = new byte[_length + 4];
data[0] = 0;
data[1] = (byte)_type;
data[2] = (byte)((_blockNumber & 0xffff) >> 8);
data[3] = (byte)(_blockNumber & 0xff);
System.arraycopy(_data, _offset, data, 4, _length);
return new DatagramPacket(data, _length + 4, _address, _port);
}
/***
* Returns the block number of the data packet.
* <p>
* @return The block number of the data packet.
***/
public int getBlockNumber()
{
return _blockNumber;
}
/*** Sets the block number of the data packet. ***/
public void setBlockNumber(int blockNumber)
{
_blockNumber = blockNumber;
}
/***
* Sets the data for the data packet.
* <p>
* @param data The byte array containing the data.
* @param offset The offset into the array where the data starts.
* @param length The length of the data.
***/
public void setData(byte[] data, int offset, int length)
{
_data = data;
_offset = offset;
_length = length;
if (length > MAX_DATA_LENGTH)
_length = MAX_DATA_LENGTH;
else
_length = length;
}
/***
* Returns the length of the data part of the data packet.
* <p>
* @return The length of the data part of the data packet.
***/
public int getDataLength()
{
return _length;
}
/***
* Returns the offset into the byte array where the packet data actually
* starts.
* <p>
* @return The offset into the byte array where the packet data actually
* starts.
***/
public int getDataOffset()
{
return _offset;
}
/***
* Returns the byte array containing the packet data.
* <p>
* @return The byte array containing the packet data.
***/
public byte[] getData()
{
return _data;
}
}