serversocket.java

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   * Accepts a new connection and returns a connected <code>Socket</code>
   * instance representing that connection.  This method will block until a
   * connection is available.
   *
   * @return socket object for the just accepted connection
   *
   * @exception IOException If an error occurs
   * @exception SecurityException If a security manager exists and its
   * checkListen method doesn't allow the operation
   * @exception IllegalBlockingModeException If this socket has an associated
   * channel, and the channel is in non-blocking mode
   * @exception SocketTimeoutException If a timeout was previously set with
   * setSoTimeout and the timeout has been reached
   */
  public Socket accept() throws IOException
  {
    Socket socket = new Socket();

    try
      {
	implAccept(socket);
      }
    catch (IOException e)
      {
	try
	  {
	    socket.close();
	  }
	catch (IOException e2)
	  {
	    // Ignore.
	  }

	throw e;
      }

    return socket;
  }

  /**
   * This protected method is used to help subclasses override
   * <code>ServerSocket.accept()</code>.  The passed in socket will be
   * connected when this method returns.
   *
   * @param socket The socket that is used for the accepted connection
   *
   * @exception IOException If an error occurs
   * @exception IllegalBlockingModeException If this socket has an associated
   * channel, and the channel is in non-blocking mode
   *
   * @since 1.1
   */
  protected final void implAccept(Socket socket) throws IOException
  {
    if (isClosed())
      throw new SocketException("ServerSocket is closed");

    // FIXME: Add a security check to make sure we're allowed to 
    // connect to the remote host.

    // The Sun spec says that if we have an associated channel and
    // it is in non-blocking mode, we throw an IllegalBlockingModeException.
    // However, in our implementation if the channel itself initiated this
    // operation, then we must honor it regardless of its blocking mode.
    if (getChannel() != null && ! getChannel().isBlocking()
        && ! ((PlainSocketImpl) getImpl()).isInChannelOperation())
      throw new IllegalBlockingModeException();

    impl.accept(socket.impl);
    socket.implCreated = true;
    socket.bound = true;
  }

  /**
   * Closes this socket and stops listening for connections
   *
   * @exception IOException If an error occurs
   */
  public void close() throws IOException
  {
    if (isClosed())
      return;

    impl.close();
    impl = null;

    if (getChannel() != null)
      getChannel().close();
  }

  /**
   * Returns the unique <code>ServerSocketChannel</code> object
   * associated with this socket, if any.
   *
   * <p>The socket only has a <code>ServerSocketChannel</code> if its created
   * by <code>ServerSocketChannel.open()</code>.</p>
   *
   * @return the associated socket channel, null if none exists
   * 
   * @since 1.4
   */
  public ServerSocketChannel getChannel()
  {
    return null;
  }

  /**
   * Returns true when the socket is bound, otherwise false
   *
   * @return true if socket is bound, false otherwise
   * 
   * @since 1.4
   */
  public boolean isBound()
  {
    return local != null;
  }

  /**
   * Returns true if the socket is closed, otherwise false
   *
   * @return true if socket is closed, false otherwise
   * 
   * @since 1.4
   */
  public boolean isClosed()
  {
    return impl == null;
  }

  /**
   * Sets the value of SO_TIMEOUT.  A value of 0 implies that SO_TIMEOUT is
   * disabled (ie, operations never time out).  This is the number of
   * milliseconds a socket operation can block before an
   * InterruptedIOException is thrown.
   *
   * @param timeout The new SO_TIMEOUT value
   *
   * @exception SocketException If an error occurs
   *
   * @since 1.1
   */
  public void setSoTimeout(int timeout) throws SocketException
  {
    if (isClosed())
      throw new SocketException("ServerSocket is closed");

    if (timeout < 0)
      throw new IllegalArgumentException("SO_TIMEOUT value must be >= 0");

    impl.setOption(SocketOptions.SO_TIMEOUT, new Integer(timeout));
  }

  /**
   * Retrieves the current value of the SO_TIMEOUT setting.  A value of 0
   * implies that SO_TIMEOUT is disabled (ie, operations never time out).
   * This is the number of milliseconds a socket operation can block before
   * an InterruptedIOException is thrown.
   *
   * @return The value of SO_TIMEOUT
   *
   * @exception IOException If an error occurs
   *
   * @since 1.1
   */
  public int getSoTimeout() throws IOException
  {
    if (isClosed())
      throw new SocketException("ServerSocket is closed");

    Object timeout = impl.getOption(SocketOptions.SO_TIMEOUT);

    if (! (timeout instanceof Integer))
      throw new IOException("Internal Error");

    return ((Integer) timeout).intValue();
  }

  /**
   * Enables/Disables the SO_REUSEADDR option
   *
   * @param on true if SO_REUSEADDR should be enabled, false otherwise
   * 
   * @exception SocketException If an error occurs
   *
   * @since 1.4
   */
  public void setReuseAddress(boolean on) throws SocketException
  {
    if (isClosed())
      throw new SocketException("ServerSocket is closed");

    impl.setOption(SocketOptions.SO_REUSEADDR, Boolean.valueOf(on));
  }

  /**
   * Checks if the SO_REUSEADDR option is enabled
   *
   * @return true if SO_REUSEADDR is set, false otherwise
   *
   * @exception SocketException If an error occurs
   *
   * @since 1.4
   */
  public boolean getReuseAddress() throws SocketException
  {
    if (isClosed())
      throw new SocketException("ServerSocket is closed");

    Object reuseaddr = impl.getOption(SocketOptions.SO_REUSEADDR);

    if (! (reuseaddr instanceof Boolean))
      throw new SocketException("Internal Error");

    return ((Boolean) reuseaddr).booleanValue();
  }

  /**
   * This method sets the value for the system level socket option
   * SO_RCVBUF to the specified value.  Note that valid values for this
   * option are specific to a given operating system.
   *
   * @param size The new receive buffer size.
   *
   * @exception SocketException If an error occurs or Socket is not connected
   * @exception IllegalArgumentException If size is 0 or negative
   *
   * @since 1.4
   */
  public void setReceiveBufferSize(int size) throws SocketException
  {
    if (isClosed())
      throw new SocketException("ServerSocket is closed");

    if (size <= 0)
      throw new IllegalArgumentException("SO_RCVBUF value must be > 0");

    impl.setOption(SocketOptions.SO_RCVBUF, new Integer(size));
  }

  /**
   * This method returns the value of the system level socket option
   * SO_RCVBUF, which is used by the operating system to tune buffer
   * sizes for data transfers.
   *
   * @return The receive buffer size.
   *
   * @exception SocketException If an error occurs or Socket is not connected
   *
   * @since 1.4
   */
  public int getReceiveBufferSize() throws SocketException
  {
    if (isClosed())
      throw new SocketException("ServerSocket is closed");

    Object buf = impl.getOption(SocketOptions.SO_RCVBUF);

    if (! (buf instanceof Integer))
      throw new SocketException("Internal Error: Unexpected type");

    return ((Integer) buf).intValue();
  }

  /**
   * Returns the value of this socket as a <code>String</code>.
   *
   * @return This socket represented as a <code>String</code>.
   */
  public String toString()
  {
    if (! isBound())
      return "ServerSocket[unbound]";

    return ("ServerSocket[addr=" + getInetAddress() + ",port="
           + impl.getPort() + ",localport=" + impl.getLocalPort() + "]");
  }

  /**
   * Sets the <code>SocketImplFactory</code> for all
   * <code>ServerSocket</code>'s.  This may only be done
   * once per virtual machine.  Subsequent attempts will generate an
   * exception.  Note that a <code>SecurityManager</code> check is made prior
   * to setting the factory.  If insufficient privileges exist to set the
   * factory, an exception will be thrown
   *
   * @param fac the factory to set
   *
   * @exception SecurityException If this operation is not allowed by the
   * <code>SecurityManager</code>.
   * @exception SocketException If the factory object is already defined
   * @exception IOException If any other error occurs
   */
  public static synchronized void setSocketFactory(SocketImplFactory fac)
    throws IOException
  {
    factory = fac;
  }
}