com.bytezone.dm3270.telnet.TelnetCommand Maven / Gradle / Ivy

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This is a trimmed down version of https://github.com/dmolony/dm3270 to be used as TN3270 client library
There is a newer version: 0.9.1
package com.bytezone.dm3270.telnet;

import com.bytezone.dm3270.buffers.AbstractTelnetCommand;
import com.bytezone.dm3270.display.Screen;
import com.bytezone.dm3270.streams.TelnetState;

import java.security.InvalidParameterException;

public class TelnetCommand extends AbstractTelnetCommand {

  public static final byte IAC = (byte) 0xFF;   // Interpret As Command
  public static final byte SB = (byte) 0xFA;    // Begin subcommand
  public static final byte SE = (byte) 0xF0;    // End of subcommmand

  private static final byte IP = (byte) 0xF4;    // Interrupt process
  private static final byte NOP = (byte) 0xF1;   // No Operation

  // double-byte commands
  private static final byte DONT = (byte) 0xFE;
  private static final byte DO = (byte) 0xFD;
  private static final byte WONT = (byte) 0xFC;
  private static final byte WILL = (byte) 0xFB;

  private final CommandName commandName;
  private final CommandType commandType;

  private enum CommandName {
    DO, DONT, WILL, WONT, NO_OP, INTERRUPT_PROCESS
  }

  private enum CommandType {
    TERMINAL_TYPE, EOR, BINARY, TN3270_EXTENDED, START_TLS
  }

  private TelnetCommand(TelnetState state, byte[] buffer) {
    this(state, buffer, buffer.length);
  }

  public TelnetCommand(TelnetState state, byte[] buffer, int length) {
    super(buffer, 0, length, state);

    byte command = buffer[1];

    if (length == 2) {
      if (command == NOP) {
        this.commandName = CommandName.NO_OP;
      } else if (command == IP) {
        this.commandName = CommandName.INTERRUPT_PROCESS;
      } else {
        throw new InvalidParameterException(
            String.format("Unknown telnet command: %02X%n", command));
      }

      commandType = null;
    } else if (length == 3) {
      byte type = buffer[2];

      if (command == DO) {
        this.commandName = CommandName.DO;
      } else if (command == DONT) {
        this.commandName = CommandName.DONT;
      } else if (command == WILL) {
        this.commandName = CommandName.WILL;
      } else if (command == WONT) {
        this.commandName = CommandName.WONT;
      } else {
        throw new InvalidParameterException(
            String.format("Unknown telnet command: %02X %02X%n", command, type));
      }

      if (type == TelnetSubcommand.TERMINAL_TYPE) {
        commandType = CommandType.TERMINAL_TYPE;
      } else if (type == TelnetSubcommand.EOR) {
        commandType = CommandType.EOR;
      } else if (type == TelnetSubcommand.BINARY) {
        commandType = CommandType.BINARY;
      } else if (type == TelnetSubcommand.TN3270E) {
        commandType = CommandType.TN3270_EXTENDED;
      } else if (type == TelnetSubcommand.START_TLS) {
        commandType = CommandType.START_TLS;
      } else {
        throw new InvalidParameterException(
            String.format("Unknown telnet command type: %02X %02X%n", command, type));
      }
    } else {
      throw new InvalidParameterException("Buffer incorrect length");
    }
  }

  @Override
  public void process(Screen screen) {
    // mainframe asks us DO xxx
    if (commandName == CommandName.DO) {
      byte[] reply = new byte[3];
      reply[0] = IAC;
      reply[1] = WONT;
      reply[2] = data[2];

      if (commandType == CommandType.TN3270_EXTENDED) {
        boolean preference = telnetState.do3270Extended();     // preference
        reply[1] = preference ? WILL : WONT;
        telnetState.setDoes3270Extended(preference);           // set actual
      } else if (commandType == CommandType.TERMINAL_TYPE) {
        boolean preference = telnetState.doTerminalType();     // preference
        reply[1] = preference ? WILL : WONT;
        telnetState.setDoesTerminalType(preference);           // set actual
      } else if (commandType == CommandType.EOR) {
        boolean preference = telnetState.doEOR();              // preference
        reply[1] = preference ? WILL : WONT;
        telnetState.setDoesEOR(preference);                    // set actual
      } else if (commandType == CommandType.BINARY) {
        boolean preference = telnetState.doBinary();           // preference
        reply[1] = preference ? WILL : WONT;
        telnetState.setDoesBinary(preference);                 // set actual
      }

      setReply(new TelnetCommand(telnetState, reply));
      // the actual reply (REPLAY)
    } else if (commandName == CommandName.WILL) {
      byte[] reply = new byte[3];
      reply[0] = IAC;

      if (commandType == CommandType.TN3270_EXTENDED) {
        reply[1] = telnetState.does3270Extended() ? DO : DONT;
        telnetState.setDoes3270Extended(true);
      }

      if (commandType == CommandType.TERMINAL_TYPE) {
        reply[1] = telnetState.doesTerminalType() ? DO : DONT;
        telnetState.setDoesTerminalType(true);
      }

      if (commandType == CommandType.EOR) {
        reply[1] = telnetState.doesEOR() ? DO : DONT;
        telnetState.setDoesEOR(true);
      }

      if (commandType == CommandType.BINARY) {
        reply[1] = telnetState.doesBinary() ? DO : DONT;
        telnetState.setDoesBinary(true);
      }

      reply[2] = data[2];
      setReply(new TelnetCommand(telnetState, reply));
    } else if (commandName == CommandName.DONT || commandName == CommandName.WONT) {
      if (commandType == CommandType.BINARY) {
        telnetState.setDoesBinary(false);
      }
      if (commandType == CommandType.TERMINAL_TYPE) {
        telnetState.setDoesTerminalType(false);
      }
      if (commandType == CommandType.TN3270_EXTENDED) {
        telnetState.setDoes3270Extended(false);
      }
      if (commandType == CommandType.EOR) {
        telnetState.setDoesEOR(false);
      }
    }
  }

  public String getName() {
    if (commandName == CommandName.NO_OP) {
      return "NoOp";
    }
    return toString();
  }

  @Override
  public String toString() {
    return String.format("%s %s", commandName, (commandType == null ? "" : commandType));
  }

}