    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 *
    038 *
    039 * @see TFTPPacket
    040 * @see TFTPPacketException
    041 * @see TFTP
    042 ***/
    043
    044public final class TFTPErrorPacket extends TFTPPacket
    045{
    046    /*** The undefined error code according to RFC 783, value 0. ***/
    047    public static final int UNDEFINED = 0;
    048
    049    /*** The file not found error code according to RFC 783, value 1. ***/
    050    public static final int FILE_NOT_FOUND = 1;
    051
    052    /*** The access violation error code according to RFC 783, value 2. ***/
    053    public static final int ACCESS_VIOLATION = 2;
    054
    055    /*** The disk full error code according to RFC 783, value 3. ***/
    056    public static final int OUT_OF_SPACE = 3;
    057
    058    /***
    059     * The illegal TFTP operation error code according to RFC 783, value 4.
    060     ***/
    061    public static final int ILLEGAL_OPERATION = 4;
    062
    063    /*** The unknown transfer id error code according to RFC 783, value 5. ***/
    064    public static final int UNKNOWN_TID = 5;
    065
    066    /*** The file already exists error code according to RFC 783, value 6. ***/
    067    public static final int FILE_EXISTS = 6;
    068
    069    /*** The no such user error code according to RFC 783, value 7. ***/
    070    public static final int NO_SUCH_USER = 7;
    071
    072    /*** The error code of this packet. ***/
    073    private final int error;
    074
    075    /*** The error message of this packet. ***/
    076    private final String message;
    077
    078    /***
    079     * Creates an error packet to be sent to a host at a given port
    080     * with an error code and error message.
    081     *
    082     * @param destination  The host to which the packet is going to be sent.
    083     * @param port  The port to which the packet is going to be sent.
    084     * @param error The error code of the packet.
    085     * @param message The error message of the packet.
    086     ***/
    087    public TFTPErrorPacket(final InetAddress destination, final int port,
    088                           final int error, final String message)
    089    {
    090        super(TFTPPacket.ERROR, destination, port);
    091
    092        this.error = error;
    093        this.message = message;
    094    }
    095
    096    /***
    097     * Creates an error packet based from a received
    098     * datagram.  Assumes the datagram is at least length 4, else an
    099     * ArrayIndexOutOfBoundsException may be thrown.
    100     *
    101     * @param datagram  The datagram containing the received error.
    102     * @throws TFTPPacketException  If the datagram isn't a valid TFTP
    103     *         error packet.
    104     ***/
    105    TFTPErrorPacket(final DatagramPacket datagram) throws TFTPPacketException
    106    {
    107        super(TFTPPacket.ERROR, datagram.getAddress(), datagram.getPort());
    108        int index, length;
    109        byte[] data;
    110        StringBuilder buffer;
    111
    112        data = datagram.getData();
    113        length = datagram.getLength();
    114
    115        if (getType() != data[1]) {
    116            throw new TFTPPacketException("TFTP operator code does not match type.");
    117        }
    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
    125        index = 4;
    126        buffer = new StringBuilder();
    127
    128        while (index < length && data[index] != 0)
    129        {
    130            buffer.append((char)data[index]);
    131            ++index;
    132        }
    133
    134        message = buffer.toString();
    135    }
    136
    137    /***
    138     * This is a method only available within the package for
    139     * implementing efficient datagram transport by elminating buffering.
    140     * It takes a datagram as an argument, and a byte buffer in which
    141     * to store the raw datagram data.  Inside the method, the data
    142     * is set as the datagram's data and the datagram returned.
    143     *
    144     * @param datagram  The datagram to create.
    145     * @param data The buffer to store the packet and to use in the datagram.
    146     * @return The datagram argument.
    147     ***/
    148    @Override
    149    DatagramPacket _newDatagram(final DatagramPacket datagram, final byte[] data)
    150    {
    151        int length;
    152
    153        length = message.length();
    154
    155        data[0] = 0;
    156        data[1] = (byte)type;
    157        data[2] = (byte)((error & 0xffff) >> 8);
    158        data[3] = (byte)(error & 0xff);
    159
    160        System.arraycopy(message.getBytes(), 0, data, 4, length);
    161
    162        data[length + 4] = 0;
    163
    164        datagram.setAddress(address);
    165        datagram.setPort(port);
    166        datagram.setData(data);
    167        datagram.setLength(length + 4);
    168
    169        return datagram;
    170    }
    171
    172
    173    /***
    174     * Creates a UDP datagram containing all the TFTP
    175     * error packet data in the proper format.
    176     * This is a method exposed to the programmer in case he
    177     * wants to implement his own TFTP client instead of using
    178     * the {@link org.apache.commons.net.tftp.TFTPClient}
    179     * class.
    180     * Under normal circumstances, you should not have a need to call this
    181     * method.
    182     *
    183     * @return A UDP datagram containing the TFTP error packet.
    184     ***/
    185    @Override
    186    public DatagramPacket newDatagram()
    187    {
    188        byte[] data;
    189        int length;
    190
    191        length = message.length();
    192
    193        data = new byte[length + 5];
    194        data[0] = 0;
    195        data[1] = (byte)type;
    196        data[2] = (byte)((error & 0xffff) >> 8);
    197        data[3] = (byte)(error & 0xff);
    198
    199        System.arraycopy(message.getBytes(), 0, data, 4, length);
    200
    201        data[length + 4] = 0;
    202
    203        return new DatagramPacket(data, data.length, address, port);
    204    }
    205
    206
    207    /***
    208     * Returns the error code of the packet.
    209     *
    210     * @return The error code of the packet.
    211     ***/
    212    public int getError()
    213    {
    214        return error;
    215    }
    216
    217
    218    /***
    219     * Returns the error message of the packet.
    220     *
    221     * @return The error message of the packet.
    222     ***/
    223    public String getMessage()
    224    {
    225        return message;
    226    }
    227
    228    /**
    229     * For debugging
    230     * @since 3.6
    231     */
    232    @Override
    233    public String toString() {
    234        return super.toString() + " ERR " + error + " " + message;
    235    }
    236}