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org.apache.commons.net.tftp.TFTPDataPacket |
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1 | /* |
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2 | * Copyright 2001-2005 The Apache Software Foundation |
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3 | * |
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4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
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5 | * you may not use this file except in compliance with the License. |
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6 | * You may obtain a copy of the License at |
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7 | * |
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8 | * http://www.apache.org/licenses/LICENSE-2.0 |
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9 | * |
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10 | * Unless required by applicable law or agreed to in writing, software |
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11 | * distributed under the License is distributed on an "AS IS" BASIS, |
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12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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13 | * See the License for the specific language governing permissions and |
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14 | * limitations under the License. |
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15 | */ |
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16 | package org.apache.commons.net.tftp; |
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17 | ||
18 | import java.net.DatagramPacket; |
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19 | import java.net.InetAddress; |
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20 | ||
21 | /*** |
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22 | * A final class derived from TFTPPacket definiing the TFTP Data |
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23 | * packet type. |
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24 | * <p> |
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25 | * Details regarding the TFTP protocol and the format of TFTP packets can |
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26 | * be found in RFC 783. But the point of these classes is to keep you |
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27 | * from having to worry about the internals. Additionally, only very |
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28 | * few people should have to care about any of the TFTPPacket classes |
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29 | * or derived classes. Almost all users should only be concerned with the |
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30 | * {@link org.apache.commons.net.tftp.TFTPClient} class |
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31 | * {@link org.apache.commons.net.tftp.TFTPClient#receiveFile receiveFile()} |
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32 | * and |
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33 | * {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()} |
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34 | * methods. |
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35 | * <p> |
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36 | * <p> |
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37 | * @author Daniel F. Savarese |
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38 | * @see TFTPPacket |
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39 | * @see TFTPPacketException |
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40 | * @see TFTP |
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41 | ***/ |
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42 | ||
43 | public final class TFTPDataPacket extends TFTPPacket |
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44 | { |
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45 | /*** The maximum number of bytes in a TFTP data packet (512) ***/ |
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46 | public static final int MAX_DATA_LENGTH = 512; |
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47 | ||
48 | /*** The minimum number of bytes in a TFTP data packet (0) ***/ |
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49 | public static final int MIN_DATA_LENGTH = 0; |
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50 | ||
51 | /*** The block number of the packet. ***/ |
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52 | int _blockNumber; |
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53 | ||
54 | /*** The length of the data. ***/ |
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55 | int _length; |
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56 | ||
57 | /*** The offset into the _data array at which the data begins. ***/ |
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58 | int _offset; |
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59 | ||
60 | /*** The data stored in the packet. ***/ |
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61 | byte[] _data; |
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62 | ||
63 | /*** |
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64 | * Creates a data packet to be sent to a host at a given port |
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65 | * with a given block number. The actual data to be sent is passed as |
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66 | * an array, an offset, and a length. The offset is the offset into |
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67 | * the byte array where the data starts. The length is the length of |
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68 | * the data. If the length is greater than MAX_DATA_LENGTH, it is |
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69 | * truncated. |
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70 | * <p> |
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71 | * @param destination The host to which the packet is going to be sent. |
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72 | * @param port The port to which the packet is going to be sent. |
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73 | * @param blockNumber The block number of the data. |
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74 | * @param data The byte array containing the data. |
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75 | * @param offset The offset into the array where the data starts. |
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76 | * @param length The length of the data. |
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77 | ***/ |
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78 | public TFTPDataPacket(InetAddress destination, int port, class="keyword">int blockNumber, |
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79 | byte[] data, int offset, class="keyword">int length) |
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80 | { |
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81 | 0 | super(TFTPPacket.DATA, destination, port); |
82 | ||
83 | 0 | _blockNumber = blockNumber; |
84 | 0 | _data = data; |
85 | 0 | _offset = offset; |
86 | ||
87 | 0 | if (length > MAX_DATA_LENGTH) |
88 | 0 | _length = MAX_DATA_LENGTH; |
89 | else |
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90 | 0 | _length = length; |
91 | 0 | } |
92 | ||
93 | public TFTPDataPacket(InetAddress destination, int port, class="keyword">int blockNumber, |
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94 | byte[] data) |
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95 | { |
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96 | 0 | this(destination, port, blockNumber, data, 0, data.length); |
97 | 0 | } |
98 | ||
99 | ||
100 | /*** |
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101 | * Creates a data packet based from a received |
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102 | * datagram. Assumes the datagram is at least length 4, else an |
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103 | * ArrayIndexOutOfBoundsException may be thrown. |
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104 | * <p> |
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105 | * @param datagram The datagram containing the received data. |
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106 | * @throws TFTPPacketException If the datagram isn't a valid TFTP |
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107 | * data packet. |
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108 | ***/ |
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109 | TFTPDataPacket(DatagramPacket datagram) throws TFTPPacketException |
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110 | { |
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111 | 0 | super(TFTPPacket.DATA, datagram.getAddress(), datagram.getPort()); |
112 | ||
113 | 0 | _data = datagram.getData(); |
114 | 0 | _offset = 4; |
115 | ||
116 | 0 | if (getType() != _data[1]) |
117 | 0 | throw new TFTPPacketException("TFTP operator code does not match type."); |
118 | ||
119 | 0 | _blockNumber = (((_data[2] & 0xff) << 8) | (_data[3] & 0xff)); |
120 | ||
121 | 0 | _length = datagram.getLength() - 4; |
122 | ||
123 | 0 | if (_length > MAX_DATA_LENGTH) |
124 | 0 | _length = MAX_DATA_LENGTH; |
125 | 0 | } |
126 | ||
127 | /*** |
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128 | * This is a method only available within the package for |
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129 | * implementing efficient datagram transport by elminating buffering. |
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130 | * It takes a datagram as an argument, and a byte buffer in which |
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131 | * to store the raw datagram data. Inside the method, the data |
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132 | * is set as the datagram's data and the datagram returned. |
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133 | * <p> |
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134 | * @param datagram The datagram to create. |
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135 | * @param data The buffer to store the packet and to use in the datagram. |
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136 | * @return The datagram argument. |
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137 | ***/ |
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138 | DatagramPacket _newDatagram(DatagramPacket datagram, byte[] data) |
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139 | { |
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140 | 0 | data[0] = 0; |
141 | 0 | data[1] = (byte)_type; |
142 | 0 | data[2] = (byte)((_blockNumber & 0xffff) >> 8); |
143 | 0 | data[3] = (byte)(_blockNumber & 0xff); |
144 | ||
145 | // Doublecheck we're not the same |
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146 | 0 | if (data != _data) |
147 | 0 | System.arraycopy(_data, _offset, data, 4, _length); |
148 | ||
149 | 0 | datagram.setAddress(_address); |
150 | 0 | datagram.setPort(_port); |
151 | 0 | datagram.setData(data); |
152 | 0 | datagram.setLength(_length + 4); |
153 | ||
154 | 0 | return datagram; |
155 | } |
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156 | ||
157 | /*** |
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158 | * Creates a UDP datagram containing all the TFTP |
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159 | * data packet data in the proper format. |
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160 | * This is a method exposed to the programmer in case he |
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161 | * wants to implement his own TFTP client instead of using |
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162 | * the {@link org.apache.commons.net.tftp.TFTPClient} |
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163 | * class. |
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164 | * Under normal circumstances, you should not have a need to call this |
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165 | * method. |
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166 | * <p> |
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167 | * @return A UDP datagram containing the TFTP data packet. |
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168 | ***/ |
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169 | public DatagramPacket newDatagram() |
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170 | { |
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171 | byte[] data; |
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172 | ||
173 | 0 | data = new byte[_length + 4]; |
174 | 0 | data[0] = 0; |
175 | 0 | data[1] = (byte)_type; |
176 | 0 | data[2] = (byte)((_blockNumber & 0xffff) >> 8); |
177 | 0 | data[3] = (byte)(_blockNumber & 0xff); |
178 | ||
179 | 0 | System.arraycopy(_data, _offset, data, 4, _length); |
180 | ||
181 | 0 | return new DatagramPacket(data, _length + 4, _address, _port); |
182 | } |
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183 | ||
184 | /*** |
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185 | * Returns the block number of the data packet. |
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186 | * <p> |
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187 | * @return The block number of the data packet. |
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188 | ***/ |
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189 | public int getBlockNumber() |
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190 | { |
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191 | 0 | return _blockNumber; |
192 | } |
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193 | ||
194 | /*** Sets the block number of the data packet. ***/ |
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195 | public void setBlockNumber(int blockNumber) |
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196 | { |
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197 | 0 | _blockNumber = blockNumber; |
198 | 0 | } |
199 | ||
200 | /*** |
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201 | * Sets the data for the data packet. |
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202 | * <p> |
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203 | * @param data The byte array containing the data. |
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204 | * @param offset The offset into the array where the data starts. |
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205 | * @param length The length of the data. |
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206 | ***/ |
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207 | public void setData(byte[] data, int offset, class="keyword">int length) |
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208 | { |
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209 | 0 | _data = data; |
210 | 0 | _offset = offset; |
211 | 0 | _length = length; |
212 | ||
213 | 0 | if (length > MAX_DATA_LENGTH) |
214 | 0 | _length = MAX_DATA_LENGTH; |
215 | else |
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216 | 0 | _length = length; |
217 | 0 | } |
218 | ||
219 | /*** |
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220 | * Returns the length of the data part of the data packet. |
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221 | * <p> |
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222 | * @return The length of the data part of the data packet. |
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223 | ***/ |
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224 | public int getDataLength() |
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225 | { |
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226 | 0 | return _length; |
227 | } |
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228 | ||
229 | /*** |
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230 | * Returns the offset into the byte array where the packet data actually |
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231 | * starts. |
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232 | * <p> |
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233 | * @return The offset into the byte array where the packet data actually |
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234 | * starts. |
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235 | ***/ |
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236 | public int getDataOffset() |
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237 | { |
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238 | 0 | return _offset; |
239 | } |
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240 | ||
241 | /*** |
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242 | * Returns the byte array containing the packet data. |
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243 | * <p> |
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244 | * @return The byte array containing the packet data. |
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245 | ***/ |
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246 | public byte[] getData() |
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247 | { |
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248 | 0 | return _data; |
249 | } |
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250 | } |
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