    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;
    109        final int length;
    110        final byte[] data;
    111        final StringBuilder 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
    120        error = (data[2] & 0xff) << 8 | data[3] & 0xff;
    121
    122        if (length < 5) {
    123            throw new TFTPPacketException("Bad error packet. No message.");
    124        }
    125
    126        index = 4;
    127        buffer = new StringBuilder();
    128
    129        while (index < length && data[index] != 0)
    130        {
    131            buffer.append((char)data[index]);
    132            ++index;
    133        }
    134
    135        message = buffer.toString();
    136    }
    137
    138    /**
    139     * This is a method only available within the package for
    140     * implementing efficient datagram transport by elminating buffering.
    141     * It takes a datagram as an argument, and a byte buffer in which
    142     * to store the raw datagram data.  Inside the method, the data
    143     * is set as the datagram's data and the datagram returned.
    144     *
    145     * @param datagram  The datagram to create.
    146     * @param data The buffer to store the packet and to use in the datagram.
    147     * @return The datagram argument.
    148     */
    149    @Override
    150    DatagramPacket newDatagram(final DatagramPacket datagram, final byte[] data)
    151    {
    152        final int length;
    153
    154        length = message.length();
    155
    156        data[0] = 0;
    157        data[1] = (byte)type;
    158        data[2] = (byte)((error & 0xffff) >> 8);
    159        data[3] = (byte)(error & 0xff);
    160
    161        System.arraycopy(message.getBytes(), 0, data, 4, length);
    162
    163        data[length + 4] = 0;
    164
    165        datagram.setAddress(address);
    166        datagram.setPort(port);
    167        datagram.setData(data);
    168        datagram.setLength(length + 4);
    169
    170        return datagram;
    171    }
    172
    173
    174    /**
    175     * Creates a UDP datagram containing all the TFTP
    176     * error packet data in the proper format.
    177     * This is a method exposed to the programmer in case he
    178     * wants to implement his own TFTP client instead of using
    179     * the {@link org.apache.commons.net.tftp.TFTPClient}
    180     * class.
    181     * Under normal circumstances, you should not have a need to call this
    182     * method.
    183     *
    184     * @return A UDP datagram containing the TFTP error packet.
    185     */
    186    @Override
    187    public DatagramPacket newDatagram()
    188    {
    189        final byte[] data;
    190        final int length;
    191
    192        length = message.length();
    193
    194        data = new byte[length + 5];
    195        data[0] = 0;
    196        data[1] = (byte)type;
    197        data[2] = (byte)((error & 0xffff) >> 8);
    198        data[3] = (byte)(error & 0xff);
    199
    200        System.arraycopy(message.getBytes(), 0, data, 4, length);
    201
    202        data[length + 4] = 0;
    203
    204        return new DatagramPacket(data, data.length, address, port);
    205    }
    206
    207
    208    /**
    209     * Returns the error code of the packet.
    210     *
    211     * @return The error code of the packet.
    212     */
    213    public int getError()
    214    {
    215        return error;
    216    }
    217
    218
    219    /**
    220     * Returns the error message of the packet.
    221     *
    222     * @return The error message of the packet.
    223     */
    224    public String getMessage()
    225    {
    226        return message;
    227    }
    228
    229    /**
    230     * For debugging
    231     * @since 3.6
    232     */
    233    @Override
    234    public String toString() {
    235        return super.toString() + " ERR " + error + " " + message;
    236    }
    237}