src/jexer/net/TelnetSocket.java

   1 /*
   2  * Jexer - Java Text User Interface
   3  *
   4  * The MIT License (MIT)
   5  *
   6  * Copyright (C) 2019 Kevin Lamonte
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a
   9  * copy of this software and associated documentation files (the "Software"),
  10  * to deal in the Software without restriction, including without limitation
  11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  12  * and/or sell copies of the Software, and to permit persons to whom the
  13  * Software is furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  21  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  24  * DEALINGS IN THE SOFTWARE.
  25  *
  26  * @author Kevin Lamonte [kevin.lamonte@gmail.com]
  27  * @version 1
  28  */
  29 package jexer.net;
  30
  31 import java.io.InputStream;
  32 import java.io.IOException;
  33 import java.io.OutputStream;
  34 import java.net.Socket;
  35
  36 /**
  37  * This class provides a Socket that performs the telnet protocol to both
  38  * establish an 8-bit clean no echo channel and expose window resize events
  39  * to the Jexer ECMA48 backend.
  40  */
  41 public class TelnetSocket extends Socket {
  42
  43     // ------------------------------------------------------------------------
  44     // Constants --------------------------------------------------------------
  45     // ------------------------------------------------------------------------
  46
  47     // Telnet protocol special characters.  Note package private access.
  48     static final int TELNET_SE         = 240;
  49     static final int TELNET_NOP        = 241;
  50     static final int TELNET_DM         = 242;
  51     static final int TELNET_BRK        = 243;
  52     static final int TELNET_IP         = 244;
  53     static final int TELNET_AO         = 245;
  54     static final int TELNET_AYT        = 246;
  55     static final int TELNET_EC         = 247;
  56     static final int TELNET_EL         = 248;
  57     static final int TELNET_GA         = 249;
  58     static final int TELNET_SB         = 250;
  59     static final int TELNET_WILL       = 251;
  60     static final int TELNET_WONT       = 252;
  61     static final int TELNET_DO         = 253;
  62     static final int TELNET_DONT       = 254;
  63     static final int TELNET_IAC        = 255;
  64     static final int C_NUL             = 0x00;
  65     static final int C_LF              = 0x0A;
  66     static final int C_CR              = 0x0D;
  67
  68     // ------------------------------------------------------------------------
  69     // Variables --------------------------------------------------------------
  70     // ------------------------------------------------------------------------
  71
  72     /**
  73      * The telnet-aware socket InputStream.
  74      */
  75     private TelnetInputStream input;
  76
  77     /**
  78      * The telnet-aware socket OutputStream.
  79      */
  80     private TelnetOutputStream output;
  81
  82
  83     /**
  84      * If true, this is a server socket (i.e. created by accept()).
  85      */
  86     boolean isServer = true;
  87
  88     /**
  89      * If true, telnet ECHO mode is set such that local echo is off and
  90      * remote echo is on.  This is appropriate for server sockets.
  91      */
  92     boolean echoMode = false;
  93
  94     /**
  95      * If true, telnet BINARY mode is enabled.  We always want this to
  96      * ensure a Unicode-safe stream.
  97      */
  98     boolean binaryMode = false;
  99
 100     /**
 101      * If true, the SUPPRESS-GO-AHEAD option is enabled.  We always want
 102      * this.
 103      */
 104     boolean goAhead = true;
 105
 106     /**
 107      * If true, request the client terminal type.
 108      */
 109     boolean doTermType = true;
 110
 111     /**
 112      * If true, request the client terminal speed.
 113      */
 114     boolean doTermSpeed = true;
 115
 116     /**
 117      * If true, request the Negotiate About Window Size option to
 118      * determine the client text width/height.
 119      */
 120     boolean doNAWS = true;
 121
 122     /**
 123      * If true, request the New Environment option to obtain the client
 124      * LOGNAME, USER, and LANG variables.
 125      */
 126     boolean doEnvironment = true;
 127
 128     /**
 129      * The terminal type reported by the client.
 130      */
 131     String terminalType = "";
 132
 133     /**
 134      * The terminal speed reported by the client.
 135      */
 136     String terminalSpeed = "";
 137
 138     // ------------------------------------------------------------------------
 139     // Constructors -----------------------------------------------------------
 140     // ------------------------------------------------------------------------
 141
 142     /**
 143      * Creates a Socket that knows the telnet protocol.  Note package private
 144      * access, this is only used by TelnetServerSocket.
 145      *
 146      * @throws IOException if an I/O error occurs
 147      */
 148     TelnetSocket() throws IOException {
 149         super();
 150     }
 151
 152     // ------------------------------------------------------------------------
 153     // Socket -----------------------------------------------------------------
 154     // ------------------------------------------------------------------------
 155
 156     /**
 157      * Returns an input stream for this socket.
 158      *
 159      * @return the input stream
 160      * @throws IOException if an I/O error occurs
 161      */
 162     @Override
 163     public InputStream getInputStream() throws IOException {
 164         if (input == null) {
 165             assert (output == null);
 166             output = new TelnetOutputStream(this, super.getOutputStream());
 167             input = new TelnetInputStream(this, super.getInputStream(), output);
 168             input.telnetSendOptions();
 169         }
 170         return input;
 171     }
 172
 173     /**
 174      * Returns an output stream for this socket.
 175      *
 176      * @return the output stream
 177      * @throws IOException if an I/O error occurs
 178      */
 179     @Override
 180     public OutputStream getOutputStream() throws IOException {
 181         if (output == null) {
 182             assert (input == null);
 183             output = new TelnetOutputStream(this, super.getOutputStream());
 184             input = new TelnetInputStream(this, super.getInputStream(), output);
 185             input.telnetSendOptions();
 186         }
 187         return output;
 188     }
 189
 190     // ------------------------------------------------------------------------
 191     // TelnetSocket -----------------------------------------------------------
 192     // ------------------------------------------------------------------------
 193
 194     /**
 195      * See if telnet server/client is in ASCII mode.
 196      *
 197      * @return if true, this connection is in ASCII mode
 198      */
 199     public boolean isAscii() {
 200         return (!binaryMode);
 201     }
 202
 203 }