TelnetCommand.java

  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.  */

  18. package org.apache.commons.net.telnet;

  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.  */

  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;

  31.     /** Interpret As Command code. Value is 255 according to RFC 854. */
  32.     public static final int IAC = 255;

  34.     /** Don't use option code. Value is 254 according to RFC 854. */
  35.     public static final int DONT = 254;

  37.     /** Request to use option code. Value is 253 according to RFC 854. */
  38.     public static final int DO = 253;

  40.     /** Refuse to use option code. Value is 252 according to RFC 854. */
  41.     public static final int WONT = 252;

  43.     /** Agree to use option code. Value is 251 according to RFC 854. */
  44.     public static final int WILL = 251;

  46.     /** Start subnegotiation code. Value is 250 according to RFC 854. */
  47.     public static final int SB = 250;

  49.     /** Go Ahead code. Value is 249 according to RFC 854. */
  50.     public static final int GA = 249;

  52.     /** Erase Line code. Value is 248 according to RFC 854. */
  53.     public static final int EL = 248;

  55.     /** Erase Character code. Value is 247 according to RFC 854. */
  56.     public static final int EC = 247;

  58.     /** Are You There code. Value is 246 according to RFC 854. */
  59.     public static final int AYT = 246;

  61.     /** Abort Output code. Value is 245 according to RFC 854. */
  62.     public static final int AO = 245;

  64.     /** Interrupt Process code. Value is 244 according to RFC 854. */
  65.     public static final int IP = 244;

  67.     /** Break code. Value is 243 according to RFC 854. */
  68.     public static final int BREAK = 243;

  70.     /** Data mark code. Value is 242 according to RFC 854. */
  71.     public static final int DM = 242;

  73.     /** No Operation code. Value is 241 according to RFC 854. */
  74.     public static final int NOP = 241;

  76.     /** End subnegotiation code. Value is 240 according to RFC 854. */
  77.     public static final int SE = 240;

  79.     /** End of record code. Value is 239. */
  80.     public static final int EOR = 239;

  82.     /** Abort code. Value is 238. */
  83.     public static final int ABORT = 238;

  85.     /** Suspend process code. Value is 237. */
  86.     public static final int SUSP = 237;

  88.     /** End of file code. Value is 236. */
  89.     public static final int EOF = 236;

  91.     /** Synchronize code. Value is 242. */
  92.     public static final int SYNCH = 242;

  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" };

  98.     private static final int FIRST_COMMAND = IAC;
  99.     private static final int LAST_COMMAND = EOF;

  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.     }

  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.     }

  121.     /** Cannot be instantiated. */
  122.     private TelnetCommand() {
  123.     }
  124. }
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