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 * http://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.telnet; 19 20 /** 21 * The TelnetCommand class cannot be instantiated and only serves as a storehouse for telnet command constants. 22 * 23 * @see org.apache.commons.net.telnet.Telnet 24 * @see org.apache.commons.net.telnet.TelnetClient 25 */ 26 27 public final class TelnetCommand { 28 /** The maximum value a command code can have. This value is 255. */ 29 public static final int MAX_COMMAND_VALUE = 255; 30 31 /** Interpret As Command code. Value is 255 according to RFC 854. */ 32 public static final int IAC = 255; 33 34 /** Don't use option code. Value is 254 according to RFC 854. */ 35 public static final int DONT = 254; 36 37 /** Request to use option code. Value is 253 according to RFC 854. */ 38 public static final int DO = 253; 39 40 /** Refuse to use option code. Value is 252 according to RFC 854. */ 41 public static final int WONT = 252; 42 43 /** Agree to use option code. Value is 251 according to RFC 854. */ 44 public static final int WILL = 251; 45 46 /** Start subnegotiation code. Value is 250 according to RFC 854. */ 47 public static final int SB = 250; 48 49 /** Go Ahead code. Value is 249 according to RFC 854. */ 50 public static final int GA = 249; 51 52 /** Erase Line code. Value is 248 according to RFC 854. */ 53 public static final int EL = 248; 54 55 /** Erase Character code. Value is 247 according to RFC 854. */ 56 public static final int EC = 247; 57 58 /** Are You There code. Value is 246 according to RFC 854. */ 59 public static final int AYT = 246; 60 61 /** Abort Output code. Value is 245 according to RFC 854. */ 62 public static final int AO = 245; 63 64 /** Interrupt Process code. Value is 244 according to RFC 854. */ 65 public static final int IP = 244; 66 67 /** Break code. Value is 243 according to RFC 854. */ 68 public static final int BREAK = 243; 69 70 /** Data mark code. Value is 242 according to RFC 854. */ 71 public static final int DM = 242; 72 73 /** No Operation code. Value is 241 according to RFC 854. */ 74 public static final int NOP = 241; 75 76 /** End subnegotiation code. Value is 240 according to RFC 854. */ 77 public static final int SE = 240; 78 79 /** End of record code. Value is 239. */ 80 public static final int EOR = 239; 81 82 /** Abort code. Value is 238. */ 83 public static final int ABORT = 238; 84 85 /** Suspend process code. Value is 237. */ 86 public static final int SUSP = 237; 87 88 /** End of file code. Value is 236. */ 89 public static final int EOF = 236; 90 91 /** Synchronize code. Value is 242. */ 92 public static final int SYNCH = 242; 93 94 /** String representations of commands. */ 95 private static final String[] commandString = { "IAC", "DONT", "DO", "WONT", "WILL", "SB", "GA", "EL", "EC", "AYT", "AO", "IP", "BRK", "DMARK", "NOP", "SE", 96 "EOR", "ABORT", "SUSP", "EOF" }; 97 98 private static final int FIRST_COMMAND = IAC; 99 private static final int LAST_COMMAND = EOF; 100 101 /** 102 * Returns the string representation of the telnet protocol command corresponding to the given command code. 103 * 104 * @param code The command code of the telnet protocol command. 105 * @return The string representation of the telnet protocol command. 106 */ 107 public static String getCommand(final int code) { 108 return commandString[FIRST_COMMAND - code]; 109 } 110 111 /** 112 * Determines if a given command code is valid. Returns true if valid, false if not. 113 * 114 * @param code The command code to test. 115 * @return True if the command code is valid, false if not. 116 **/ 117 public static boolean isValidCommand(final int code) { 118 return code <= FIRST_COMMAND && code >= LAST_COMMAND; 119 } 120 121 /** Cannot be instantiated. */ 122 private TelnetCommand() { 123 } 124 }