/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.tomcat.util.net;

import java.io.IOException;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Hashtable;

/**
 * This class creates server sockets.  It may be subclassed by other
 * factories, which create particular types of server sockets.  This
 * provides a general framework for the addition of public socket-level
 * functionality.  It it is the server side analogue of a socket factory,
 * and similarly provides a way to capture a variety of policies related
 * to the sockets being constructed.
 *
 * <P> Like socket factories, Server Socket factory instances have two
 * categories of methods.  First are methods used to create sockets.
 * Second are methods which set properties used in the production of
 * sockets, such as networking options.  There is also an environment
 * specific default server socket factory; frameworks will often use
 * their own customized factory.
 * 
 * <P><hr><em> It may be desirable to move this interface into the
 * <b>java.net</b> package, so that is not an extension but the preferred
 * interface.  Should this be serializable, making it a JavaBean which can
 * be saved along with its networking configuration?
 * </em>   
 *
 * @author db@eng.sun.com
 * @author Harish Prabandham
 */
public abstract class ServerSocketFactory implements Cloneable {

    //
    // NOTE:  JDK 1.1 bug in class GC, this can get collected
    // even though it's always accessible via getDefault().
    //

    private static ServerSocketFactory theFactory;
    protected Hashtable attributes=new Hashtable();

    /**
     * Constructor is used only by subclasses.
     */

    protected ServerSocketFactory () {
        /* NOTHING */
    }

    /** General mechanism to pass attributes from the
     *  ServerConnector to the socket factory.
     *
     *  Note that the "prefered" mechanism is to
     *  use bean setters and explicit methods, but
     *  this allows easy configuration via server.xml
     *  or simple Properties
     */
    public void setAttribute( String name, Object value ) {
	if( name!=null && value !=null)
	    attributes.put( name, value );
    }
    
    /**
     * Returns a copy of the environment's default socket factory.
     */
    public static synchronized ServerSocketFactory getDefault () {
        //
        // optimize typical case:  no synch needed
        //

        if (theFactory == null) {
            //
            // Different implementations of this method could
            // work rather differently.  For example, driving
            // this from a system property, or using a different
            // implementation than JavaSoft's.
            //

            theFactory = new DefaultServerSocketFactory ();
        }

        try {
            return (ServerSocketFactory) theFactory.clone ();
        } catch (CloneNotSupportedException e) {
            throw new RuntimeException (e.getMessage ());
        }
    }

    /**
     * Returns a server socket which uses all network interfaces on
     * the host, and is bound to a the specified port.  The socket is
     * configured with the socket options (such as accept timeout)
     * given to this factory.
     *
     * @param port the port to listen to
     * @exception IOException for networking errors
     * @exception InstantiationException for construction errors
     */
    public abstract ServerSocket createSocket (int port)
    throws IOException, InstantiationException;

    /**
     * Returns a server socket which uses all network interfaces on
     * the host, is bound to a the specified port, and uses the 
     * specified connection backlog.  The socket is configured with
     * the socket options (such as accept timeout) given to this factory.
     *
     * @param port the port to listen to
     * @param backlog how many connections are queued
     * @exception IOException for networking errors
     * @exception InstantiationException for construction errors
     */

    public abstract ServerSocket createSocket (int port, int backlog)
    throws IOException, InstantiationException;

    /**
     * Returns a server socket which uses only the specified network
     * interface on the local host, is bound to a the specified port,
     * and uses the specified connection backlog.  The socket is configured
     * with the socket options (such as accept timeout) given to this factory.
     *
     * @param port the port to listen to
     * @param backlog how many connections are queued
     * @param ifAddress the network interface address to use
     * @exception IOException for networking errors
     * @exception InstantiationException for construction errors
     */

    public abstract ServerSocket createSocket (int port,
        int backlog, InetAddress ifAddress)
    throws IOException, InstantiationException;

    public void initSocket( Socket s ) {
    }
 
     /**
       Wrapper function for accept(). This allows us to trap and
       translate exceptions if necessary
 
       @exception IOException;
     */ 
     public abstract Socket acceptSocket(ServerSocket socket)
 	throws IOException;
 
     /**
       Extra function to initiate the handshake. Sometimes necessary
       for SSL
 
       @exception IOException;
     */ 
     public abstract void handshake(Socket sock)
 	throws IOException;
}