serversocket.java

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/* ServerSocket.java -- Class for implementing server side sockets
   Copyright (C) 1998, 1999, 2000, 2002 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
 
GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */

package java.net;

import java.io.IOException;
import java.nio.channels.IllegalBlockingModeException;
import java.nio.channels.ServerSocketChannel;

/* Written using on-line Java Platform 1.2 API Specification.
 * Status:  I believe all methods are implemented.
 */

/**
 * This class models server side sockets.  The basic model is that the
 * server socket is created and bound to some well known port.  It then
 * listens for and accepts connections.  At that point the client and
 * server sockets are ready to communicate with one another utilizing
 * whatever application layer protocol they desire.
 *
 * As with the <code>Socket</code> class, most instance methods of this class 
 * simply redirect their calls to an implementation class.
 *
 * @author Aaron M. Renn ([e-mail])
 * @author Per Bothner ([e-mail])
 */
public class ServerSocket
{
  /**
   * This is the user defined SocketImplFactory, if one is supplied
   */
  private static SocketImplFactory factory;

  /**
   * This is the SocketImp object to which most instance methods in this
   * class are redirected
   */
  private SocketImpl impl;

  /**
   * ServerSocketChannel of this ServerSocket. This channel only exists
   * when the socket is created by ServerSocketChannel.open().
   */
  private ServerSocketChannel ch;

  private boolean closed = false;
  
  /**
   * Constructor that simply sets the implementation.
   * 
   * @exception IOException If an error occurs
   *
   * @specnote This constructor is public since JDK 1.4
   */
  public ServerSocket() throws IOException
  {
    if (factory != null)
      impl = factory.createSocketImpl();
    else
      impl = new PlainSocketImpl();

    impl.create(true);
  }

  /**
   * Creates a server socket and binds it to the specified port.  If the
   * port number is 0, a random free port will be chosen.  The pending
   * connection queue on this socket will be set to 50.
   *
   * @param port The port number to bind to
   * 
   * @exception IOException If an error occurs
   * @exception SecurityException If a security manager exists and its
   * checkListen method doesn't allow the operation
   */
  public ServerSocket (int port)
    throws IOException
  {
    this(port, 50);
  }

  /**
   * Creates a server socket and binds it to the specified port.  If the
   * port number is 0, a random free port will be chosen.  The pending
   * connection queue on this socket will be set to the value passed as
   * arg2.
   *
   * @param port The port number to bind to
   * @param backlog The length of the pending connection queue
   *
   * @exception IOException If an error occurs
   * @exception SecurityException If a security manager exists and its
   * checkListen method doesn't allow the operation
   */
  public ServerSocket (int port, int backlog)
    throws IOException
  {
    this(port, backlog, null);
  }

  /**
   * Creates a server socket and binds it to the specified port.  If the
   * port number is 0, a random free port will be chosen.  The pending
   * connection queue on this socket will be set to the value passed as
   * backlog.  The third argument specifies a particular local address to
   * bind t or null to bind to all local address.
   *
   * @param port The port number to bind to
   * @param backlog The length of the pending connection queue
   * @param bindAddr The address to bind to, or null to bind to all addresses
   *
   * @exception IOException If an error occurs
   * @exception SecurityException If a security manager exists and its
   * checkListen method doesn't allow the operation
   *
   * @since 1.1
   */
  public ServerSocket (int port, int backlog, InetAddress bindAddr)
    throws IOException
  {
    this();

    if (impl == null)
      throw new IOException("Cannot initialize Socket implementation");

    SecurityManager s = System.getSecurityManager();
    if (s != null)
      s.checkListen(port);

    if (bindAddr == null)
      bindAddr = InetAddress.ANY_IF;

    impl.create(true);
    impl.bind(bindAddr, port);
    impl.listen(backlog);
  }

  /**
   * Binds the server socket to a specified socket address
   *
   * @param endpoint The socket address to bind to
   *
   * @exception IOException If an error occurs
   * @exception IllegalArgumentException If address type is not supported
   * @exception SecurityException If a security manager exists and its
   * checkListen method doesn't allow the operation
   * 
   * @since 1.4
   */
  public void bind (SocketAddress endpoint)
    throws IOException
  {
    bind (endpoint, 50);
  }
 
  /**
   * Binds the server socket to a specified socket address
   *
   * @param endpoint The socket address to bind to
   * @param backlog The length of the pending connection queue
   * 
   * @exception IOException If an error occurs
   * @exception IllegalArgumentException If address type is not supported
   * @exception SecurityException If a security manager exists and its
   * checkListen method doesn't allow the operation
   *
   * @since 1.4
   */
  public void bind (SocketAddress endpoint, int backlog) throws IOException
  {
    if (closed)
      throw new SocketException ("ServerSocket is closed");
    
    if (impl == null)
      throw new IOException ("Cannot initialize Socket implementation");

    if (! (endpoint instanceof InetSocketAddress))
      throw new IllegalArgumentException ("Address type not supported");

    InetSocketAddress tmp = (InetSocketAddress) endpoint;
    
    SecurityManager s = System.getSecurityManager ();
    if (s != null)
      s.checkListen (tmp.getPort ());

    impl.bind (tmp.getAddress (), tmp.getPort ());
    impl.listen(backlog);
  }
  
  /**
   * This method returns the local address to which this socket is bound
   *
   * @return The socket's local address
   */
  public InetAddress getInetAddress()
  {
    try
      {
        return (InetAddress) impl.getOption (SocketOptions.SO_BINDADDR);
      }
    catch (SocketException e)
      {
        return null;
      }
  }

  /**
   * This method returns the local port number to which this socket is bound
   *
   * @return The socket's port number
   */
  public int getLocalPort()
  {
    return impl.getLocalPort();
  }

  /**
   * Returns the local socket address
   *
   * @since 1.4
   */
  public SocketAddress getLocalSocketAddress()
  {
    InetAddress addr = getInetAddress();

    if (addr != null)
      return new InetSocketAddress (getInetAddress(), getLocalPort());

    return null;
  }

  /**
   * Accepts a new connection and returns a connected <code>Socket</code>