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
018 package 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 * @author Daniel F. Savarese
024 * @see org.apache.commons.net.telnet.Telnet
025 * @see org.apache.commons.net.telnet.TelnetClient
026 */
027
028 public final class TelnetCommand
029 {
030 /*** The maximum value a command code can have. This value is 255. ***/
031 public static final int MAX_COMMAND_VALUE = 255;
032
033 /*** Interpret As Command code. Value is 255 according to RFC 854. ***/
034 public static final int IAC = 255;
035
036 /*** Don't use option code. Value is 254 according to RFC 854. ***/
037 public static final int DONT = 254;
038
039 /*** Request to use option code. Value is 253 according to RFC 854. ***/
040 public static final int DO = 253;
041
042 /*** Refuse to use option code. Value is 252 according to RFC 854. ***/
043 public static final int WONT = 252;
044
045 /*** Agree to use option code. Value is 251 according to RFC 854. ***/
046 public static final int WILL = 251;
047
048 /*** Start subnegotiation code. Value is 250 according to RFC 854. ***/
049 public static final int SB = 250;
050
051 /*** Go Ahead code. Value is 249 according to RFC 854. ***/
052 public static final int GA = 249;
053
054 /*** Erase Line code. Value is 248 according to RFC 854. ***/
055 public static final int EL = 248;
056
057 /*** Erase Character code. Value is 247 according to RFC 854. ***/
058 public static final int EC = 247;
059
060 /*** Are You There code. Value is 246 according to RFC 854. ***/
061 public static final int AYT = 246;
062
063 /*** Abort Output code. Value is 245 according to RFC 854. ***/
064 public static final int AO = 245;
065
066 /*** Interrupt Process code. Value is 244 according to RFC 854. ***/
067 public static final int IP = 244;
068
069 /*** Break code. Value is 243 according to RFC 854. ***/
070 public static final int BREAK = 243;
071
072 /*** Data mark code. Value is 242 according to RFC 854. ***/
073 public static final int DM = 242;
074
075 /*** No Operation code. Value is 241 according to RFC 854. ***/
076 public static final int NOP = 241;
077
078 /*** End subnegotiation code. Value is 240 according to RFC 854. ***/
079 public static final int SE = 240;
080
081 /*** End of record code. Value is 239. ***/
082 public static final int EOR = 239;
083
084 /*** Abort code. Value is 238. ***/
085 public static final int ABORT = 238;
086
087 /*** Suspend process code. Value is 237. ***/
088 public static final int SUSP = 237;
089
090 /*** End of file code. Value is 236. ***/
091 public static final int EOF = 236;
092
093 /*** Synchronize code. Value is 242. ***/
094 public static final int SYNCH = 242;
095
096 /*** String representations of commands. ***/
097 private static final String __commandString[] = {
098 "IAC", "DONT", "DO", "WONT", "WILL", "SB", "GA", "EL", "EC", "AYT",
099 "AO", "IP", "BRK", "DMARK", "NOP", "SE", "EOR", "ABORT", "SUSP", "EOF"
100 };
101
102 private static final int __FIRST_COMMAND = IAC;
103 private static final int __LAST_COMMAND = EOF;
104
105 /***
106 * Returns the string representation of the telnet protocol command
107 * corresponding to the given command code.
108 * <p>
109 * @param code The command code of the telnet protocol command.
110 * @return The string representation of the telnet protocol command.
111 ***/
112 public static final String getCommand(int code)
113 {
114 return __commandString[__FIRST_COMMAND - code];
115 }
116
117 /***
118 * Determines if a given command code is valid. Returns true if valid,
119 * false if not.
120 * <p>
121 * @param code The command code to test.
122 * @return True if the command code is valid, false if not.
123 **/
124 public static final boolean isValidCommand(int code)
125 {
126 return (code <= __FIRST_COMMAND && code >= __LAST_COMMAND);
127 }
128
129 // Cannot be instantiated
130 private TelnetCommand()
131 { }
132 }