portlistener.java

telnetD源代码

//License
/***
 * Java TelnetD library (embeddable telnet daemon)
 * Copyright (c) 2000-2005 Dieter Wimberger 
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the author nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *  
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS ``AS
 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 ***/

package net.wimpi.telnetd.net;

import net.wimpi.telnetd.BootException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.text.MessageFormat;
import java.util.Properties;

/**
 * Class that implements a <tt>PortListener</tt>.<br>
 * If available, it accepts incoming connections and passes them
 * to an associated <tt>ConnectionManager</tt>.
 *
 * @author Dieter Wimberger
 * @version 2.0 (13/03/2005)
 * @see net.wimpi.telnetd.net.ConnectionManager
 */
public class PortListener
    implements Runnable {

  private static Log log = LogFactory.getLog(PortListener.class);

  private String m_Name;
  private int m_Port;							            //port number running on
  private int m_FloodProtection;					    //flooding protection
  private ServerSocket m_ServerSocket = null; //server socket

  private Thread m_Thread;
  private ConnectionManager m_ConnectionManager;	//connection management thread
  private boolean m_Stopping = false;
  private boolean m_Available;               		//Flag for availability


  /**
   * Constructs a PortListener instance.<br>
   * Its private because its called by a factory method.
   *
   * @param port      int that specifies the port number of the server socket.
   * @param floodprot that specifies the server socket queue size.
   */
  private PortListener(String name, int port, int floodprot) {
    m_Name = name;
    m_Available = false;
    m_Port = port;
    m_FloodProtection = floodprot;
  }//constructor

  /**
   * Returns the name of this <tt>PortListener</tt>.
   *
   * @return the name as <tt>String</tt>.
   */
  public String getName() {
    return m_Name;
  }//getName

  /**
   * Tests if this <tt>PortListener</tt> is available.
   *
   * @return true if available, false otherwise.
   */
  public boolean isAvailable() {
    return m_Available;
  }//isAvailable

  /**
   * Sets the availability flag of this <tt>PortListener</tt>.
   *
   * @param b true if to be available, false otherwise.
   */
  public void setAvailable(boolean b) {
    m_Available = b;
  }//setAvailable

  /**
   * Starts this <tt>PortListener</tt>.
   */
  public void start() {
    log.debug("start()");
    m_Thread = new Thread(this);
    m_Thread.start();
    m_Available = true;
  }//start

  /**
   * Stops this <tt>PortListener</tt>, and returns
   * when everything was stopped successfully.
   */
  public void stop() {
    log.debug("stop()::"+ this.toString());
    //flag stop
    m_Stopping = true;
    m_Available = false;
    //take down all connections
    m_ConnectionManager.stop();

    //close server socket
    try {
      m_ServerSocket.close();
    } catch (IOException ex) {
      log.error("stop()", ex);
    }

    //wait for thread to die
    try {
      m_Thread.join();
    } catch (InterruptedException iex) {
      log.error("stop()", iex);
    }

    log.info("stop()::Stopped " + this.toString());
  }//stop

  /**
   * Listen constantly to a server socket and handles incoming connections
   * through the associated {a:link ConnectionManager}.
   *
   * @see net.wimpi.telnetd.net.ConnectionManager
   */
  public void run() {
    try {
      /*
          A server socket is opened with a connectivity queue of a size specified
          in int floodProtection.  Concurrent login handling under normal circumstances
          should be handled properly, but denial of service attacks via massive parallel
          program logins should be prevented with this.
      */
      m_ServerSocket = new ServerSocket(m_Port, m_FloodProtection);

      //log entry
      Object[] args = {new Integer(m_Port), new Integer(m_FloodProtection)};
      log.info(MessageFormat.format(logmsg, args));

      do {
        try {
          Socket s = m_ServerSocket.accept();
          if (m_Available) {
            m_ConnectionManager.makeConnection(s);
          } else {
            //just shut down the socket
            s.close();
          }
        } catch (SocketException ex) {
          if (m_Stopping) {
            //server socket was closed blocked in accept
            log.debug("run(): ServerSocket closed by stop()");
          } else {
            log.error("run()", ex);
          }
        }
      } while (!m_Stopping);

    } catch (IOException e) {
      log.error("run()", e);
    }
    log.debug("run(): returning.");
  }//run


  /**
   * Returns reference to ConnectionManager instance associated
   * with the PortListener.
   *
   * @return the associated ConnectionManager.
   */
  public ConnectionManager getConnectionManager() {
    return m_ConnectionManager;
  }//getConnectionManager


  /**
   * Factory method for a PortListener instance, returns
   * an instance of a PortListener with an associated ConnectionManager.
   *
   * @param settings Properties that contain all configuration information.
   */
  public static PortListener createPortListener(String name, Properties settings)
      throws BootException {

    PortListener pl = null;

    try {
      //1. read settings of the port listener itself
      int port = Integer.parseInt(settings.getProperty(name + ".port"));
      int floodprot = Integer.parseInt(settings.getProperty(name + ".floodprotection"));

      if (new Boolean(settings.getProperty(name + ".secure")).booleanValue()) {
        //do nothing for now, probably set factory in the future
      }
      pl = new PortListener(name, port, floodprot);
    } catch (Exception ex) {
      log.error("createPortListener()", ex);
      throw new BootException("Failure while creating PortListener instance:\n" +
          ex.getMessage());
    }

    //2. factorize a ConnectionManager, passing the settings, if we do not have one yet
    if (pl.m_ConnectionManager == null) {
      pl.m_ConnectionManager = ConnectionManager.createConnectionManager(name, settings);
      try {
        pl.m_ConnectionManager.start();
      } catch (Exception exc) {
        log.error("createPortListener()", exc);
        throw new BootException("Failure while starting ConnectionManager watchdog thread:\n" +
            exc.getMessage());
      }
    }
    return pl;
  }//createPortListener

  private static final String logmsg =
      "Listening to Port {0,number,integer} with a connectivity queue size of {1,number,integer}.";

}//class PortListener