/*

 * Copyright 1995-2006 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.net;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.FileDescriptor;

/**

 * The abstract class <code>SocketImpl</code> is a common superclass

 * of all classes that actually implement sockets. It is used to

 * create both client and server sockets.

 * <p>

 * A "plain" socket implements these methods exactly as

 * described, without attempting to go through a firewall or proxy.

 *

 * @author  unascribed

 * @since   JDK1.0

 */

public abstract class SocketImpl implements SocketOptions {

    /**

     * The actual Socket object.

     */

    Socket socket = null;

    ServerSocket serverSocket = null;

    /**

     * The file descriptor object for this socket.

     */

    protected FileDescriptor fd;

    /**

     * The IP address of the remote end of this socket.

     */

    protected InetAddress address;

    /**

     * The port number on the remote host to which this socket is connected.

     */

    protected int port;

    /**

     * The local port number to which this socket is connected.

     */

    protected int localport;

    /**

     * Creates either a stream or a datagram socket.

     *

     * @param      stream   if <code>true</code>, create a stream socket;

     *                      otherwise, create a datagram socket.

     * @exception  IOException  if an I/O error occurs while creating the

     *               socket.

     */

    protected abstract void create(boolean stream) throws IOException;

    /**

     * Connects this socket to the specified port on the named host.

     *

     * @param      host   the name of the remote host.

     * @param      port   the port number.

     * @exception  IOException  if an I/O error occurs when connecting to the

     *               remote host.

     */

    protected abstract void connect(String host, int port) throws IOException;

    /**

     * Connects this socket to the specified port number on the specified host.

     *

     * @param      address   the IP address of the remote host.

     * @param      port      the port number.

     * @exception  IOException  if an I/O error occurs when attempting a

     *               connection.

     */

    protected abstract void connect(InetAddress address, int port) throws IOException;

    /**

     * Connects this socket to the specified port number on the specified host.

     * A timeout of zero is interpreted as an infinite timeout. The connection

     * will then block until established or an error occurs.

     *

     * @param      address   the Socket address of the remote host.

     * @param     timeout  the timeout value, in milliseconds, or zero for no timeout.

     * @exception  IOException  if an I/O error occurs when attempting a

     *               connection.

     * @since 1.4

     */

    protected abstract void connect(SocketAddress address, int timeout) throws IOException;

    /**

     * Binds this socket to the specified local IP address and port number.

     *

     * @param      host   an IP address that belongs to a local interface.

     * @param      port   the port number.

     * @exception  IOException  if an I/O error occurs when binding this socket.

     */

    protected abstract void bind(InetAddress host, int port) throws IOException;

    /**

     * Sets the maximum queue length for incoming connection indications

     * (a request to connect) to the <code>count</code> argument. If a

     * connection indication arrives when the queue is full, the

     * connection is refused.

     *

     * @param      backlog   the maximum length of the queue.

     * @exception  IOException  if an I/O error occurs when creating the queue.

     */

    protected abstract void listen(int backlog) throws IOException;

    /**

     * Accepts a connection.

     *

     * @param      s   the accepted connection.

     * @exception  IOException  if an I/O error occurs when accepting the

     *               connection.

     */

    protected abstract void accept(SocketImpl s) throws IOException;

    /**

     * Returns an input stream for this socket.

     *

     * @return     a stream for reading from this socket.

     * @exception  IOException  if an I/O error occurs when creating the

     *               input stream.

    */

    protected abstract InputStream getInputStream() throws IOException;

    /**

     * Returns an output stream for this socket.

     *

     * @return     an output stream for writing to this socket.

     * @exception  IOException  if an I/O error occurs when creating the

     *               output stream.

     */

    protected abstract OutputStream getOutputStream() throws IOException;

    /**

     * Returns the number of bytes that can be read from this socket

     * without blocking.

     *

     * @return     the number of bytes that can be read from this socket

     *             without blocking.

     * @exception  IOException  if an I/O error occurs when determining the

     *               number of bytes available.

     */

    protected abstract int available() throws IOException;

    /**

     * Closes this socket.

     *

     * @exception  IOException  if an I/O error occurs when closing this socket.

     */

    protected abstract void close() throws IOException;

    /**

     * Places the input stream for this socket at "end of stream".

     * Any data sent to this socket is acknowledged and then

     * silently discarded.

     *

     * If you read from a socket input stream after invoking

     * shutdownInput() on the socket, the stream will return EOF.

     *

     * @exception IOException if an I/O error occurs when shutting down this

     * socket.

     * @see java.net.Socket#shutdownOutput()

     * @see java.net.Socket#close()

     * @see java.net.Socket#setSoLinger(boolean, int)

     * @since 1.3

     */

    protected void shutdownInput() throws IOException {

      throw new IOException("Method not implemented!");

    }

    /**

     * Disables the output stream for this socket.

     * For a TCP socket, any previously written data will be sent

     * followed by TCP's normal connection termination sequence.

     *

     * If you write to a socket output stream after invoking

     * shutdownOutput() on the socket, the stream will throw

     * an IOException.

     *

     * @exception IOException if an I/O error occurs when shutting down this

     * socket.

     * @see java.net.Socket#shutdownInput()

     * @see java.net.Socket#close()

     * @see java.net.Socket#setSoLinger(boolean, int)

     * @since 1.3

     */

    protected void shutdownOutput() throws IOException {

      throw new IOException("Method not implemented!");

    }

    /**

     * Returns the value of this socket's <code>fd</code> field.

     *

     * @return  the value of this socket's <code>fd</code> field.

     * @see     java.net.SocketImpl#fd

     */

    protected FileDescriptor getFileDescriptor() {

        return fd;

    }

    /**

     * Returns the value of this socket's <code>address</code> field.

     *

     * @return  the value of this socket's <code>address</code> field.

     * @see     java.net.SocketImpl#address

     */

    protected InetAddress getInetAddress() {

        return address;

    }

    /**

     * Returns the value of this socket's <code>port</code> field.

     *

     * @return  the value of this socket's <code>port</code> field.

     * @see     java.net.SocketImpl#port

     */

    protected int getPort() {

        return port;

    }

    /**

     * Returns whether or not this SocketImpl supports sending

     * urgent data. By default, false is returned

     * unless the method is overridden in a sub-class

     *

     * @return  true if urgent data supported

     * @see     java.net.SocketImpl#address

     * @since 1.4

     */

    protected boolean supportsUrgentData () {

        return false; // must be overridden in sub-class

    }

    /**

     * Send one byte of urgent data on the socket.

     * The byte to be sent is the low eight bits of the parameter

     * @param data The byte of data to send

     * @exception IOException if there is an error

     *  sending the data.

     * @since 1.4

     */

    protected abstract void sendUrgentData (int data) throws IOException;

    /**

     * Returns the value of this socket's <code>localport</code> field.

     *

     * @return  the value of this socket's <code>localport</code> field.

     * @see     java.net.SocketImpl#localport

     */

    protected int getLocalPort() {

        return localport;

    }

    void setSocket(Socket soc) {

        this.socket = soc;

    }

    Socket getSocket() {

        return socket;

    }

    void setServerSocket(ServerSocket soc) {

        this.serverSocket = soc;

    }

    ServerSocket getServerSocket() {

        return serverSocket;

    }

    /**

     * Returns the address and port of this socket as a <code>String</code>.

     *

     * @return  a string representation of this socket.

     */

    public String toString() {

        return "Socket[addr=" + getInetAddress() +

            ",port=" + getPort() + ",localport=" + getLocalPort()  + "]";

    }

    void reset() throws IOException {

        address = null;

        port = 0;

        localport = 0;

    }

    /**

     * Sets performance preferences for this socket.

     *

     * <p> Sockets use the TCP/IP protocol by default.  Some implementations

     * may offer alternative protocols which have different performance

     * characteristics than TCP/IP.  This method allows the application to

     * express its own preferences as to how these tradeoffs should be made

     * when the implementation chooses from the available protocols.

     *

     * <p> Performance preferences are described by three integers

     * whose values indicate the relative importance of short connection time,

     * low latency, and high bandwidth.  The absolute values of the integers

     * are irrelevant; in order to choose a protocol the values are simply

     * compared, with larger values indicating stronger preferences. Negative

     * values represent a lower priority than positive values. If the

     * application prefers short connection time over both low latency and high

     * bandwidth, for example, then it could invoke this method with the values

     * <tt>(1, 0, 0)</tt>.  If the application prefers high bandwidth above low

     * latency, and low latency above short connection time, then it could

     * invoke this method with the values <tt>(0, 1, 2)</tt>.

     *

     * By default, this method does nothing, unless it is overridden in a

     * a sub-class.

     *

     * @param  connectionTime

     *         An <tt>int</tt> expressing the relative importance of a short

     *         connection time

     *

     * @param  latency

     *         An <tt>int</tt> expressing the relative importance of low

     *         latency

     *

     * @param  bandwidth

     *         An <tt>int</tt> expressing the relative importance of high

     *         bandwidth

     *

     * @since 1.5

     */

    protected void setPerformancePreferences(int connectionTime,

                                          int latency,

                                          int bandwidth)

    {

        /* Not implemented yet */

    }

}