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What this is

This file is included in the "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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The source code

 * Copyright 2001-2004 The Apache Software Foundation
 * Licensed 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
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.

 * 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 * TFTPClient class * receiveFile() * and * sendFile() * methods. *


* @author Daniel F. Savarese * @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. ***/ 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 TFTPClient * class. Under normal circumstances, you should not have a need to call this * method. *

* @return A UDP datagram containing the TFTP acknowledgement packet. ***/ 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. ***/ public void setBlockNumber(int blockNumber) { _blockNumber = blockNumber; } }

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