
/*
 * Created on Nov 23, 2004
 *
 * TODO To change the template for this generated file go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
package UnreliableNetwork;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocketImpl;
import java.net.InetAddress;
import java.net.SocketAddress;
import java.net.SocketException;

/**
 * @author marcod
 *
 * TODO To change the template for this generated type comment go to
 * Window - Preferences - Java - Code Style - Code Templates
 */
public class DatagramSocket extends java.net.DatagramSocket {

        /**
         * threshold, packets where Math random returns less than this are lost ... 
         */
        double threshold = 0.0;
        /** by default 10% of the packets get lost

         *  Using the DatagramSocket(int,InetAddress,double) constructor,
         *  you can set up the proper value of lost packets (a double in 
         *  the range [0,1] 0 => no packets lost, 1 => all packets are lost
         */
        private final double defaultThreshold = 0.1;
        /**
         * @throws java.net.SocketException
         */
        public DatagramSocket() throws SocketException {
                super();
                threshold = defaultThreshold;
        }

        /**
         * @param arg0
         */
        public DatagramSocket(DatagramSocketImpl arg0) {
                super(arg0);
                threshold = defaultThreshold;
        }

        /**
         * @param arg0
         * @throws java.net.SocketException
         */
        public DatagramSocket(SocketAddress arg0) throws SocketException {
                super(arg0);
                threshold = defaultThreshold;
        }

        /**
         * @param arg0
         * @throws java.net.SocketException
         */
        public DatagramSocket(int arg0) throws SocketException {
                super(arg0);
                threshold = defaultThreshold;
        }

        /**
         * @param arg0
         * @param arg1
         * @throws java.net.SocketException
         */
        public DatagramSocket(int arg0, InetAddress arg1) throws SocketException {
                super(arg0, arg1);
                threshold = defaultThreshold;
        }

        public DatagramSocket(int arg0, InetAddress arg1, double threshold) throws SocketException {
                super(arg0, arg1);
                this.threshold = threshold;
        }



        /** questo di fatto è l'unico metodo "modificato" rispetto ai metodi originali
         *  se il valore pseuodcasuale stà sotto alla soglia, il pacchetto viene scartato ma dal punto di vista
         *  di chi invoca la send è come se fosse stato spedito ... 
         */
        public void send(DatagramPacket p) throws IOException {
                double random = Math.random();
                if(random < threshold) {
                        System.out.println("!!! Packet LOST: to "+p.getAddress() + " port "+ p.getPort());
                        return;
                }
                // System.out.println("Packet sent: to "+p.getAddress() + " port "+ p.getPort());
                super.send(p);
                
        }
}