001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.net.tftp;
019
020import java.net.DatagramPacket;
021import java.net.InetAddress;
022
023/***
024 * A final class derived from TFTPPacket definiing the TFTP Error
025 * packet type.
026 * <p>
027 * Details regarding the TFTP protocol and the format of TFTP packets can
028 * be found in RFC 783.  But the point of these classes is to keep you
029 * from having to worry about the internals.  Additionally, only very
030 * few people should have to care about any of the TFTPPacket classes
031 * or derived classes.  Almost all users should only be concerned with the
032 * {@link org.apache.commons.net.tftp.TFTPClient} class
033 * {@link org.apache.commons.net.tftp.TFTPClient#receiveFile receiveFile()}
034 * and
035 * {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()}
036 * methods.
037 * <p>
038 * <p>
039 * @author Daniel F. Savarese
040 * @see TFTPPacket
041 * @see TFTPPacketException
042 * @see TFTP
043 ***/
044
045public final class TFTPErrorPacket extends TFTPPacket
046{
047    /*** The undefined error code according to RFC 783, value 0. ***/
048    public static final int UNDEFINED = 0;
049
050    /*** The file not found error code according to RFC 783, value 1. ***/
051    public static final int FILE_NOT_FOUND = 1;
052
053    /*** The access violation error code according to RFC 783, value 2. ***/
054    public static final int ACCESS_VIOLATION = 2;
055
056    /*** The disk full error code according to RFC 783, value 3. ***/
057    public static final int OUT_OF_SPACE = 3;
058
059    /***
060     * The illegal TFTP operation error code according to RFC 783, value 4.
061     ***/
062    public static final int ILLEGAL_OPERATION = 4;
063
064    /*** The unknown transfer id error code according to RFC 783, value 5. ***/
065    public static final int UNKNOWN_TID = 5;
066
067    /*** The file already exists error code according to RFC 783, value 6. ***/
068    public static final int FILE_EXISTS = 6;
069
070    /*** The no such user error code according to RFC 783, value 7. ***/
071    public static final int NO_SUCH_USER = 7;
072
073    /*** The error code of this packet. ***/
074    int _error;
075
076    /*** The error message of this packet. ***/
077    String _message;
078
079    /***
080     * Creates an error packet to be sent to a host at a given port
081     * with an error code and error message.
082     * <p>
083     * @param destination  The host to which the packet is going to be sent.
084     * @param port  The port to which the packet is going to be sent.
085     * @param error The error code of the packet.
086     * @param message The error message of the packet.
087     ***/
088    public TFTPErrorPacket(InetAddress destination, int port,
089                           int error, String message)
090    {
091        super(TFTPPacket.ERROR, destination, port);
092
093        _error = error;
094        _message = message;
095    }
096
097    /***
098     * Creates an error packet based from a received
099     * datagram.  Assumes the datagram is at least length 4, else an
100     * ArrayIndexOutOfBoundsException may be thrown.
101     * <p>
102     * @param datagram  The datagram containing the received error.
103     * @throws TFTPPacketException  If the datagram isn't a valid TFTP
104     *         error packet.
105     ***/
106    TFTPErrorPacket(DatagramPacket datagram) throws TFTPPacketException
107    {
108        super(TFTPPacket.ERROR, datagram.getAddress(), datagram.getPort());
109        int index, length;
110        byte[] data;
111        StringBuffer buffer;
112
113        data = datagram.getData();
114        length = datagram.getLength();
115
116        if (getType() != data[1])
117            throw new TFTPPacketException("TFTP operator code does not match type.");
118
119        _error = (((data[2] & 0xff) << 8) | (data[3] & 0xff));
120
121        if (length < 5)
122            throw new TFTPPacketException("Bad error packet. No message.");
123
124        index = 4;
125        buffer = new StringBuffer();
126
127        while (index < length && data[index] != 0)
128        {
129            buffer.append((char)data[index]);
130            ++index;
131        }
132
133        _message = buffer.toString();
134    }
135
136    /***
137     * This is a method only available within the package for
138     * implementing efficient datagram transport by elminating buffering.
139     * It takes a datagram as an argument, and a byte buffer in which
140     * to store the raw datagram data.  Inside the method, the data
141     * is set as the datagram's data and the datagram returned.
142     * <p>
143     * @param datagram  The datagram to create.
144     * @param data The buffer to store the packet and to use in the datagram.
145     * @return The datagram argument.
146     ***/
147    @Override
148    DatagramPacket _newDatagram(DatagramPacket datagram, byte[] data)
149    {
150        int length;
151
152        length = _message.length();
153
154        data[0] = 0;
155        data[1] = (byte)_type;
156        data[2] = (byte)((_error & 0xffff) >> 8);
157        data[3] = (byte)(_error & 0xff);
158
159        System.arraycopy(_message.getBytes(), 0, data, 4, length);
160
161        data[length + 4] = 0;
162
163        datagram.setAddress(_address);
164        datagram.setPort(_port);
165        datagram.setData(data);
166        datagram.setLength(length + 4);
167
168        return datagram;
169    }
170
171
172    /***
173     * Creates a UDP datagram containing all the TFTP
174     * error packet data in the proper format.
175     * This is a method exposed to the programmer in case he
176     * wants to implement his own TFTP client instead of using
177     * the {@link org.apache.commons.net.tftp.TFTPClient}
178     * class.
179     * Under normal circumstances, you should not have a need to call this
180     * method.
181     * <p>
182     * @return A UDP datagram containing the TFTP error packet.
183     ***/
184    @Override
185    public DatagramPacket newDatagram()
186    {
187        byte[] data;
188        int length;
189
190        length = _message.length();
191
192        data = new byte[length + 5];
193        data[0] = 0;
194        data[1] = (byte)_type;
195        data[2] = (byte)((_error & 0xffff) >> 8);
196        data[3] = (byte)(_error & 0xff);
197
198        System.arraycopy(_message.getBytes(), 0, data, 4, length);
199
200        data[length + 4] = 0;
201
202        return new DatagramPacket(data, data.length, _address, _port);
203    }
204
205
206    /***
207     * Returns the error code of the packet.
208     * <p>
209     * @return The error code of the packet.
210     ***/
211    public int getError()
212    {
213        return _error;
214    }
215
216
217    /***
218     * Returns the error message of the packet.
219     * <p>
220     * @return The error message of the packet.
221     ***/
222    public String getMessage()
223    {
224        return _message;
225    }
226}