| /* |
| * 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; |
| |
| /*** |
| * TFTPPacket is an abstract class encapsulating the functionality common |
| * to the 5 types of TFTP packets. It also provides a static factory |
| * method that will create the correct TFTP packet instance from a |
| * datagram. This relieves the programmer from having to figure out what |
| * kind of TFTP packet is contained in a datagram and create it himself. |
| * <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 TFTPPacketException |
| * @see TFTP |
| ***/ |
| |
| public abstract class TFTPPacket |
| { |
| /*** |
| * The minimum size of a packet. This is 4 bytes. It is enough |
| * to store the opcode and blocknumber or other required data |
| * depending on the packet type. |
| ***/ |
| static final int MIN_PACKET_SIZE = 4; |
| |
| /*** |
| * This is the actual TFTP spec |
| * identifier and is equal to 1. |
| * Identifier returned by {@link #getType getType()} |
| * indicating a read request packet. |
| ***/ |
| public static final int READ_REQUEST = 1; |
| |
| /*** |
| * This is the actual TFTP spec |
| * identifier and is equal to 2. |
| * Identifier returned by {@link #getType getType()} |
| * indicating a write request packet. |
| ***/ |
| public static final int WRITE_REQUEST = 2; |
| |
| /*** |
| * This is the actual TFTP spec |
| * identifier and is equal to 3. |
| * Identifier returned by {@link #getType getType()} |
| * indicating a data packet. |
| ***/ |
| public static final int DATA = 3; |
| |
| /*** |
| * This is the actual TFTP spec |
| * identifier and is equal to 4. |
| * Identifier returned by {@link #getType getType()} |
| * indicating an acknowledgement packet. |
| ***/ |
| public static final int ACKNOWLEDGEMENT = 4; |
| |
| /*** |
| * This is the actual TFTP spec |
| * identifier and is equal to 5. |
| * Identifier returned by {@link #getType getType()} |
| * indicating an error packet. |
| ***/ |
| public static final int ERROR = 5; |
| |
| /*** |
| * The TFTP data packet maximum segment size in bytes. This is 512 |
| * and is useful for those familiar with the TFTP protocol who want |
| * to use the {@link org.apache.commons.net.tftp.TFTP} |
| * class methods to implement their own TFTP servers or clients. |
| ***/ |
| public static final int SEGMENT_SIZE = 512; |
| |
| /*** The type of packet. ***/ |
| int _type; |
| |
| /*** The port the packet came from or is going to. ***/ |
| int _port; |
| |
| /*** The host the packet is going to be sent or where it came from. ***/ |
| InetAddress _address; |
| |
| /*** |
| * When you receive a datagram that you expect to be a TFTP packet, you use |
| * this factory method to create the proper TFTPPacket object |
| * encapsulating the data contained in that datagram. This method is the |
| * only way you can instantiate a TFTPPacket derived class from a |
| * datagram. |
| * <p> |
| * @param datagram The datagram containing a TFTP packet. |
| * @return The TFTPPacket object corresponding to the datagram. |
| * @exception TFTPPacketException If the datagram does not contain a valid |
| * TFTP packet. |
| ***/ |
| public final static TFTPPacket newTFTPPacket(DatagramPacket datagram) |
| throws TFTPPacketException |
| { |
| byte[] data; |
| TFTPPacket packet = null; |
| |
| if (datagram.getLength() < MIN_PACKET_SIZE) |
| throw new TFTPPacketException( |
| "Bad packet. Datagram data length is too short."); |
| |
| data = datagram.getData(); |
| |
| switch (data[1]) |
| { |
| case READ_REQUEST: |
| packet = new TFTPReadRequestPacket(datagram); |
| break; |
| case WRITE_REQUEST: |
| packet = new TFTPWriteRequestPacket(datagram); |
| break; |
| case DATA: |
| packet = new TFTPDataPacket(datagram); |
| break; |
| case ACKNOWLEDGEMENT: |
| packet = new TFTPAckPacket(datagram); |
| break; |
| case ERROR: |
| packet = new TFTPErrorPacket(datagram); |
| break; |
| default: |
| throw new TFTPPacketException( |
| "Bad packet. Invalid TFTP operator code."); |
| } |
| |
| return packet; |
| } |
| |
| /*** |
| * This constructor is not visible outside of the package. It is used |
| * by subclasses within the package to initialize base data. |
| * <p> |
| * @param type The type of the packet. |
| * @param address The host the packet came from or is going to be sent. |
| * @param port The port the packet came from or is going to be sent. |
| **/ |
| TFTPPacket(int type, InetAddress address, int port) |
| { |
| _type = type; |
| _address = address; |
| _port = port; |
| } |
| |
| /*** |
| * This is an abstract 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 |
| * should be 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. |
| ***/ |
| abstract DatagramPacket _newDatagram(DatagramPacket datagram, byte[] data); |
| |
| /*** |
| * Creates a UDP datagram containing all the TFTP packet |
| * data in the proper format. |
| * This is an abstract 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 packet. |
| ***/ |
| public abstract DatagramPacket newDatagram(); |
| |
| /*** |
| * Returns the type of the packet. |
| * <p> |
| * @return The type of the packet. |
| ***/ |
| public final int getType() |
| { |
| return _type; |
| } |
| |
| /*** |
| * Returns the address of the host where the packet is going to be sent |
| * or where it came from. |
| * <p> |
| * @return The type of the packet. |
| ***/ |
| public final InetAddress getAddress() |
| { |
| return _address; |
| } |
| |
| /*** |
| * Returns the port where the packet is going to be sent |
| * or where it came from. |
| * <p> |
| * @return The port where the packet came from or where it is going. |
| ***/ |
| public final int getPort() |
| { |
| return _port; |
| } |
| |
| /*** Sets the port where the packet is going to be sent. ***/ |
| public final void setPort(int port) |
| { |
| _port = port; |
| } |
| |
| /*** Sets the host address where the packet is going to be sent. ***/ |
| public final void setAddress(InetAddress address) |
| { |
| _address = address; |
| } |
| } |
