src/jexer/net/TelnetSocket.java

   1 /**
   2  * Jexer - Java Text User Interface
   3  *
   4  * License: LGPLv3 or later
   5  *
   6  * This module is licensed under the GNU Lesser General Public License
   7  * Version 3.  Please see the file "COPYING" in this directory for more
   8  * information about the GNU Lesser General Public License Version 3.
   9  *
  10  *     Copyright (C) 2015  Kevin Lamonte
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU Lesser General Public License
  14  * as published by the Free Software Foundation; either version 3 of
  15  * the License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Lesser General Public
  23  * License along with this program; if not, see
  24  * http://www.gnu.org/licenses/, or write to the Free Software
  25  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  26  * 02110-1301 USA
  27  *
  28  * @author Kevin Lamonte [kevin.lamonte@gmail.com]
  29  * @version 1
  30  */
  31 package jexer.net;
  32
  33 import java.io.InputStream;
  34 import java.io.IOException;
  35 import java.io.OutputStream;
  36 import java.net.Socket;
  37
  38 /**
  39  * This class provides a Socket that performs the telnet protocol to both
  40  * establish an 8-bit clean no echo channel and expose window resize events
  41  * to the Jexer ECMA48 backend.
  42  */
  43 public final class TelnetSocket extends Socket {
  44
  45     /**
  46      * The wrapped socket.
  47      */
  48     private Socket socket;
  49
  50     /**
  51      * The telnet-aware socket InputStream.
  52      */
  53     private TelnetInputStream input;
  54
  55     /**
  56      * The telnet-aware socket OutputStream. Note package private access:
  57      * input sends stuff to output.
  58      */
  59     TelnetOutputStream output;
  60
  61     // Telnet protocol special characters.  Note package private access.
  62     public static final int TELNET_SE         = 240;
  63     public static final int TELNET_NOP        = 241;
  64     public static final int TELNET_DM         = 242;
  65     public static final int TELNET_BRK        = 243;
  66     public static final int TELNET_IP         = 244;
  67     public static final int TELNET_AO         = 245;
  68     public static final int TELNET_AYT        = 246;
  69     public static final int TELNET_EC         = 247;
  70     public static final int TELNET_EL         = 248;
  71     public static final int TELNET_GA         = 249;
  72     public static final int TELNET_SB         = 250;
  73     public static final int TELNET_WILL       = 251;
  74     public static final int TELNET_WONT       = 252;
  75     public static final int TELNET_DO         = 253;
  76     public static final int TELNET_DONT       = 254;
  77     public static final int TELNET_IAC        = 255;
  78     public static final int C_NUL             = 0x00;
  79     public static final int C_LF              = 0x0A;
  80     public static final int C_CR              = 0x0D;
  81
  82     /**
  83      * Telnet protocol speaks to a Network Virtual Terminal (NVT).
  84      */
  85     class TelnetState {
  86
  87         // General status flags outside the NVT spec
  88         boolean doInit;
  89         boolean isServer;
  90
  91         // NVT flags
  92         boolean echoMode;
  93         boolean binaryMode;
  94         boolean goAhead;
  95         boolean doTermType;
  96         boolean doTermSpeed;
  97         boolean doNAWS;
  98         boolean doEnvironment;
  99         String terminal = "";
 100
 101         // Flags used by the TelnetInputStream
 102         boolean iac;
 103         boolean dowill;
 104         int dowillType;
 105         boolean subnegEnd;
 106         boolean isEof;
 107         boolean eofMsg;
 108         boolean readCR;
 109
 110         // Flags used by the TelnetOutputStream
 111         boolean writeCR;
 112
 113         /**
 114          * Constuctor calls reset().
 115          */
 116         public TelnetState() {
 117             reset();
 118         }
 119
 120         /**
 121          * Reset NVT to default state as per RFC 854.
 122          */
 123         public void reset() {
 124             echoMode            = false;
 125             binaryMode          = false;
 126             goAhead             = true;
 127             doTermType          = true;
 128             doTermSpeed         = true;
 129             doNAWS              = true;
 130             doEnvironment       = true;
 131             doInit              = true;
 132             isServer            = true;
 133
 134             iac                 = false;
 135             dowill              = false;
 136             subnegEnd           = false;
 137             isEof               = false;
 138             eofMsg              = false;
 139             readCR              = false;
 140
 141             writeCR             = false;
 142         }
 143     }
 144
 145     /**
 146      * State of the protocol.  Note package private access.
 147      */
 148     TelnetState nvt;
 149
 150     /**
 151      * See if telnet server/client is in ASCII mode.
 152      *
 153      * @return if true, this connection is in ASCII mode
 154      */
 155     public boolean isAscii() {
 156         return (!nvt.binaryMode);
 157     }
 158
 159     /**
 160      * Creates a Socket that knows the telnet protocol.
 161      *
 162      * @param socket the underlying Socket
 163      */
 164     TelnetSocket(Socket socket) throws IOException {
 165         super();
 166         nvt = new TelnetState();
 167         this.socket = socket;
 168
 169         output = new TelnetOutputStream(this, super.getOutputStream());
 170         input = new TelnetInputStream(this, super.getInputStream(), output);
 171
 172         // Initiate the telnet protocol negotiation.
 173         input.telnetSendOptions();
 174     }
 175
 176     // Socket interface -------------------------------------------------------
 177
 178     /**
 179      * Returns an input stream for this socket.
 180      *
 181      * @return the input stream
 182      */
 183     @Override
 184     public InputStream getInputStream() throws IOException {
 185         return input;
 186     }
 187
 188     /**
 189      * Returns an output stream for this socket.
 190      *
 191      * @return the output stream
 192      */
 193     @Override
 194     public OutputStream getOutputStream() throws IOException {
 195         return output;
 196     }
 197
 198 }