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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      https://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.net.tftp;
19  
20  import java.net.DatagramPacket;
21  import java.net.InetAddress;
22  import java.nio.charset.Charset;
23  
24  /**
25   * A final class derived from TFTPPacket defining the TFTP Error packet type.
26   * <p>
27   * 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
28   * 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
29   * should only be concerned with the {@link org.apache.commons.net.tftp.TFTPClient} class {@link org.apache.commons.net.tftp.TFTPClient#receiveFile
30   * receiveFile()} and {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()} methods.
31   * </p>
32   *
33   * @see TFTPPacket
34   * @see TFTPPacketException
35   * @see TFTP
36   */
37  
38  public final class TFTPErrorPacket extends TFTPPacket {
39      /** The undefined error code according to RFC 783, value 0. */
40      public static final int UNDEFINED = 0;
41  
42      /** The file not found error code according to RFC 783, value 1. */
43      public static final int FILE_NOT_FOUND = 1;
44  
45      /** The access violation error code according to RFC 783, value 2. */
46      public static final int ACCESS_VIOLATION = 2;
47  
48      /** The disk full error code according to RFC 783, value 3. */
49      public static final int OUT_OF_SPACE = 3;
50  
51      /**
52       * The illegal TFTP operation error code according to RFC 783, value 4.
53       */
54      public static final int ILLEGAL_OPERATION = 4;
55  
56      /** The unknown transfer id error code according to RFC 783, value 5. */
57      public static final int UNKNOWN_TID = 5;
58  
59      /** The file already exists error code according to RFC 783, value 6. */
60      public static final int FILE_EXISTS = 6;
61  
62      /** The no such user error code according to RFC 783, value 7. */
63      public static final int NO_SUCH_USER = 7;
64  
65      /**
66       * The invalid options error code according to RFC 2347, value 8.
67       *
68       * @since 3.12.0
69       */
70      public static final int INVALID_OPTIONS_VALUE = 8;
71  
72      /** The error code of this packet. */
73      private final int error;
74  
75      /** The error message of this packet. */
76      private final String message;
77  
78      /**
79       * Creates an error packet based from a received datagram. Assumes the datagram is at least length 4, else an ArrayIndexOutOfBoundsException may be thrown.
80       *
81       * @param datagram The datagram containing the received error.
82       * @throws TFTPPacketException If the datagram isn't a valid TFTP error packet.
83       */
84      TFTPErrorPacket(final DatagramPacket datagram) throws TFTPPacketException {
85          super(ERROR, datagram.getAddress(), datagram.getPort());
86          int index;
87          final int length;
88          final byte[] data;
89          final StringBuilder buffer;
90  
91          data = datagram.getData();
92          length = datagram.getLength();
93  
94          if (getType() != data[1]) {
95              throw new TFTPPacketException("TFTP operator code does not match type.");
96          }
97  
98          error = (data[2] & 0xff) << 8 | data[3] & 0xff;
99  
100         if (length < 5) {
101             throw new TFTPPacketException("Bad error packet. No message.");
102         }
103 
104         index = 4;
105         buffer = new StringBuilder();
106 
107         while (index < length && data[index] != 0) {
108             buffer.append((char) data[index]);
109             ++index;
110         }
111 
112         message = buffer.toString();
113     }
114 
115     /**
116      * Creates an error packet to be sent to a host at a given port with an error code and error message.
117      *
118      * @param destination The host to which the packet is going to be sent.
119      * @param port        The port to which the packet is going to be sent.
120      * @param error       The error code of the packet.
121      * @param message     The error message of the packet.
122      */
123     public TFTPErrorPacket(final InetAddress destination, final int port, final int error, final String message) {
124         super(ERROR, destination, port);
125 
126         this.error = error;
127         this.message = message;
128     }
129 
130     /**
131      * Gets the error code of the packet.
132      *
133      * @return The error code of the packet.
134      */
135     public int getError() {
136         return error;
137     }
138 
139     /**
140      * Gets the error message of the packet.
141      *
142      * @return The error message of the packet.
143      */
144     public String getMessage() {
145         return message;
146     }
147 
148     /**
149      * Creates a UDP datagram containing all the TFTP error packet data in the proper format. This is a method exposed to the programmer in case he wants to
150      * implement his own TFTP client instead of using the {@link org.apache.commons.net.tftp.TFTPClient} class. Under normal circumstances, you should not have
151      * a need to call this method.
152      *
153      * @return A UDP datagram containing the TFTP error packet.
154      */
155     @Override
156     public DatagramPacket newDatagram() {
157         final byte[] data;
158         final int length;
159 
160         length = message.length();
161 
162         data = new byte[length + 5];
163         data[0] = 0;
164         data[1] = (byte) type;
165         data[2] = (byte) ((error & 0xffff) >> 8);
166         data[3] = (byte) (error & 0xff);
167 
168         System.arraycopy(message.getBytes(Charset.defaultCharset()), 0, data, 4, length);
169 
170         data[length + 4] = 0;
171 
172         return new DatagramPacket(data, data.length, address, port);
173     }
174 
175     /**
176      * This is a method only available within the package for implementing efficient datagram transport by eliminating buffering. It takes a datagram as an
177      * 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.
178      *
179      * @param datagram The datagram to create.
180      * @param data     The buffer to store the packet and to use in the datagram.
181      * @return The datagram argument.
182      */
183     @Override
184     DatagramPacket newDatagram(final DatagramPacket datagram, final byte[] data) {
185         final int length;
186 
187         length = message.length();
188 
189         data[0] = 0;
190         data[1] = (byte) type;
191         data[2] = (byte) ((error & 0xffff) >> 8);
192         data[3] = (byte) (error & 0xff);
193 
194         System.arraycopy(message.getBytes(Charset.defaultCharset()), 0, data, 4, length);
195 
196         data[length + 4] = 0;
197 
198         datagram.setAddress(address);
199         datagram.setPort(port);
200         datagram.setData(data);
201         datagram.setLength(length + 4);
202 
203         return datagram;
204     }
205 
206     /**
207      * For debugging
208      *
209      * @since 3.6
210      */
211     @Override
212     public String toString() {
213         return super.toString() + " ERR " + error + " " + message;
214     }
215 }