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.telnet; 019 020/** 021 * The TelnetCommand class cannot be instantiated and only serves as a 022 * storehouse for telnet command constants. 023 * @see org.apache.commons.net.telnet.Telnet 024 * @see org.apache.commons.net.telnet.TelnetClient 025 */ 026 027public final class TelnetCommand 028{ 029 /** The maximum value a command code can have. This value is 255. */ 030 public static final int MAX_COMMAND_VALUE = 255; 031 032 /** Interpret As Command code. Value is 255 according to RFC 854. */ 033 public static final int IAC = 255; 034 035 /** Don't use option code. Value is 254 according to RFC 854. */ 036 public static final int DONT = 254; 037 038 /** Request to use option code. Value is 253 according to RFC 854. */ 039 public static final int DO = 253; 040 041 /** Refuse to use option code. Value is 252 according to RFC 854. */ 042 public static final int WONT = 252; 043 044 /** Agree to use option code. Value is 251 according to RFC 854. */ 045 public static final int WILL = 251; 046 047 /** Start subnegotiation code. Value is 250 according to RFC 854. */ 048 public static final int SB = 250; 049 050 /** Go Ahead code. Value is 249 according to RFC 854. */ 051 public static final int GA = 249; 052 053 /** Erase Line code. Value is 248 according to RFC 854. */ 054 public static final int EL = 248; 055 056 /** Erase Character code. Value is 247 according to RFC 854. */ 057 public static final int EC = 247; 058 059 /** Are You There code. Value is 246 according to RFC 854. */ 060 public static final int AYT = 246; 061 062 /** Abort Output code. Value is 245 according to RFC 854. */ 063 public static final int AO = 245; 064 065 /** Interrupt Process code. Value is 244 according to RFC 854. */ 066 public static final int IP = 244; 067 068 /** Break code. Value is 243 according to RFC 854. */ 069 public static final int BREAK = 243; 070 071 /** Data mark code. Value is 242 according to RFC 854. */ 072 public static final int DM = 242; 073 074 /** No Operation code. Value is 241 according to RFC 854. */ 075 public static final int NOP = 241; 076 077 /** End subnegotiation code. Value is 240 according to RFC 854. */ 078 public static final int SE = 240; 079 080 /** End of record code. Value is 239. */ 081 public static final int EOR = 239; 082 083 /** Abort code. Value is 238. */ 084 public static final int ABORT = 238; 085 086 /** Suspend process code. Value is 237. */ 087 public static final int SUSP = 237; 088 089 /** End of file code. Value is 236. */ 090 public static final int EOF = 236; 091 092 /** Synchronize code. Value is 242. */ 093 public static final int SYNCH = 242; 094 095 /** String representations of commands. */ 096 private static final String commandString[] = { 097 "IAC", "DONT", "DO", "WONT", "WILL", "SB", "GA", "EL", "EC", "AYT", 098 "AO", "IP", "BRK", "DMARK", "NOP", "SE", "EOR", "ABORT", "SUSP", "EOF" 099 }; 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 String getCommand(final 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 boolean isValidCommand(final int code) 124 { 125 return code <= FIRST_COMMAND && code >= LAST_COMMAND; 126 } 127 128 // Cannot be instantiated 129 private TelnetCommand() 130 { } 131}