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 22 * storehouse for telnet command constants. 23 * @see org.apache.commons.net.telnet.Telnet 24 * @see org.apache.commons.net.telnet.TelnetClient 25 */ 26 27 public final class TelnetCommand 28 { 29 /*** The maximum value a command code can have. This value is 255. ***/ 30 public static final int MAX_COMMAND_VALUE = 255; 31 32 /*** Interpret As Command code. Value is 255 according to RFC 854. ***/ 33 public static final int IAC = 255; 34 35 /*** Don't use option code. Value is 254 according to RFC 854. ***/ 36 public static final int DONT = 254; 37 38 /*** Request to use option code. Value is 253 according to RFC 854. ***/ 39 public static final int DO = 253; 40 41 /*** Refuse to use option code. Value is 252 according to RFC 854. ***/ 42 public static final int WONT = 252; 43 44 /*** Agree to use option code. Value is 251 according to RFC 854. ***/ 45 public static final int WILL = 251; 46 47 /*** Start subnegotiation code. Value is 250 according to RFC 854. ***/ 48 public static final int SB = 250; 49 50 /*** Go Ahead code. Value is 249 according to RFC 854. ***/ 51 public static final int GA = 249; 52 53 /*** Erase Line code. Value is 248 according to RFC 854. ***/ 54 public static final int EL = 248; 55 56 /*** Erase Character code. Value is 247 according to RFC 854. ***/ 57 public static final int EC = 247; 58 59 /*** Are You There code. Value is 246 according to RFC 854. ***/ 60 public static final int AYT = 246; 61 62 /*** Abort Output code. Value is 245 according to RFC 854. ***/ 63 public static final int AO = 245; 64 65 /*** Interrupt Process code. Value is 244 according to RFC 854. ***/ 66 public static final int IP = 244; 67 68 /*** Break code. Value is 243 according to RFC 854. ***/ 69 public static final int BREAK = 243; 70 71 /*** Data mark code. Value is 242 according to RFC 854. ***/ 72 public static final int DM = 242; 73 74 /*** No Operation code. Value is 241 according to RFC 854. ***/ 75 public static final int NOP = 241; 76 77 /*** End subnegotiation code. Value is 240 according to RFC 854. ***/ 78 public static final int SE = 240; 79 80 /*** End of record code. Value is 239. ***/ 81 public static final int EOR = 239; 82 83 /*** Abort code. Value is 238. ***/ 84 public static final int ABORT = 238; 85 86 /*** Suspend process code. Value is 237. ***/ 87 public static final int SUSP = 237; 88 89 /*** End of file code. Value is 236. ***/ 90 public static final int EOF = 236; 91 92 /*** Synchronize code. Value is 242. ***/ 93 public static final int SYNCH = 242; 94 95 /*** String representations of commands. ***/ 96 private static final String __commandString[] = { 97 "IAC", "DONT", "DO", "WONT", "WILL", "SB", "GA", "EL", "EC", "AYT", 98 "AO", "IP", "BRK", "DMARK", "NOP", "SE", "EOR", "ABORT", "SUSP", "EOF" 99 }; 100 101 private static final int __FIRST_COMMAND = IAC; 102 private static final int __LAST_COMMAND = EOF; 103 104 /*** 105 * Returns the string representation of the telnet protocol command 106 * corresponding to the given command code. 107 * <p> 108 * @param code The command code of the telnet protocol command. 109 * @return The string representation of the telnet protocol command. 110 ***/ 111 public static final String getCommand(int code) 112 { 113 return __commandString[__FIRST_COMMAND - code]; 114 } 115 116 /*** 117 * Determines if a given command code is valid. Returns true if valid, 118 * false if not. 119 * <p> 120 * @param code The command code to test. 121 * @return True if the command code is valid, false if not. 122 **/ 123 public static final boolean isValidCommand(int code) 124 { 125 return (code <= __FIRST_COMMAND && code >= __LAST_COMMAND); 126 } 127 128 // Cannot be instantiated 129 private TelnetCommand() 130 { } 131 }