001 /*
002 * Copyright 2001-2005 The Apache Software Foundation
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016 package org.apache.commons.net.telnet;
017
018 /**
019 * The TelnetCommand class cannot be instantiated and only serves as a
020 * storehouse for telnet command constants.
021 * @author Daniel F. Savarese
022 * @see org.apache.commons.net.telnet.Telnet
023 * @see org.apache.commons.net.telnet.TelnetClient
024 */
025
026 public final class TelnetCommand
027 {
028 /*** The maximum value a command code can have. This value is 255. ***/
029 public static final int MAX_COMMAND_VALUE = 255;
030
031 /*** Interpret As Command code. Value is 255 according to RFC 854. ***/
032 public static final int IAC = 255;
033
034 /*** Don't use option code. Value is 254 according to RFC 854. ***/
035 public static final int DONT = 254;
036
037 /*** Request to use option code. Value is 253 according to RFC 854. ***/
038 public static final int DO = 253;
039
040 /*** Refuse to use option code. Value is 252 according to RFC 854. ***/
041 public static final int WONT = 252;
042
043 /*** Agree to use option code. Value is 251 according to RFC 854. ***/
044 public static final int WILL = 251;
045
046 /*** Start subnegotiation code. Value is 250 according to RFC 854. ***/
047 public static final int SB = 250;
048
049 /*** Go Ahead code. Value is 249 according to RFC 854. ***/
050 public static final int GA = 249;
051
052 /*** Erase Line code. Value is 248 according to RFC 854. ***/
053 public static final int EL = 248;
054
055 /*** Erase Character code. Value is 247 according to RFC 854. ***/
056 public static final int EC = 247;
057
058 /*** Are You There code. Value is 246 according to RFC 854. ***/
059 public static final int AYT = 246;
060
061 /*** Abort Output code. Value is 245 according to RFC 854. ***/
062 public static final int AO = 245;
063
064 /*** Interrupt Process code. Value is 244 according to RFC 854. ***/
065 public static final int IP = 244;
066
067 /*** Break code. Value is 243 according to RFC 854. ***/
068 public static final int BREAK = 243;
069
070 /*** Data mark code. Value is 242 according to RFC 854. ***/
071 public static final int DM = 242;
072
073 /*** No Operation code. Value is 241 according to RFC 854. ***/
074 public static final int NOP = 241;
075
076 /*** End subnegotiation code. Value is 240 according to RFC 854. ***/
077 public static final int SE = 240;
078
079 /*** End of record code. Value is 239. ***/
080 public static final int EOR = 239;
081
082 /*** Abort code. Value is 238. ***/
083 public static final int ABORT = 238;
084
085 /*** Suspend process code. Value is 237. ***/
086 public static final int SUSP = 237;
087
088 /*** End of file code. Value is 236. ***/
089 public static final int EOF = 236;
090
091 /*** Synchronize code. Value is 242. ***/
092 public static final int SYNCH = 242;
093
094 /*** String representations of commands. ***/
095 private static final String __commandString[] = {
096 "IAC", "DONT", "DO", "WONT", "WILL", "SB", "GA", "EL", "EC", "AYT",
097 "AO", "IP", "BRK", "DMARK", "NOP", "SE", "EOR", "ABORT", "SUSP", "EOF"
098 };
099
100 private static final int __FIRST_COMMAND = IAC;
101 private static final int __LAST_COMMAND = EOF;
102
103 /***
104 * Returns the string representation of the telnet protocol command
105 * corresponding to the given command code.
106 * <p>
107 * @param code The command code of the telnet protocol command.
108 * @return The string representation of the telnet protocol command.
109 ***/
110 public static final String getCommand(int code)
111 {
112 return __commandString[__FIRST_COMMAND - code];
113 }
114
115 /***
116 * Determines if a given command code is valid. Returns true if valid,
117 * false if not.
118 * <p>
119 * @param code The command code to test.
120 * @return True if the command code is valid, false if not.
121 **/
122 public static final boolean isValidCommand(int code)
123 {
124 return (code <= __FIRST_COMMAND && code >= __LAST_COMMAND);
125 }
126
127 // Cannot be instantiated
128 private TelnetCommand()
129 { }
130 }