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/*
* Jitsi, the OpenSource Java VoIP and Instant Messaging client.
*
* Distributable under LGPL license.
* See terms of license at gnu.org.
*/
package net.java.sip.communicator.impl.provdisc.dhcp;
import java.net.*;
import java.util.*;
import net.java.sip.communicator.util.*;
/**
* DHCP transaction class.
*
* @author Sebastien Vincent
*/
public class DHCPTransaction
{
/**
* Logger.
*/
private final Logger logger
= Logger.getLogger(DHCPTransaction.class);
/**
* Number of retransmission before giving up.
*/
private int maxRetransmit = 2;
/**
* Current number of retransmission.
*/
private int nbRetransmit = 0;
/**
* Fix interval for retransmission. This final interval will be obtained
* by adding a random number between [-1, 1].
*/
private int interval = 2;
/**
* The Timer that will trigger retransmission.
*/
private Timer timer = null;
/**
* The DHCP packet content.
*/
private final DatagramPacket message;
/**
* The socket that will be used to retransmit DHCP packet.
*/
private final DatagramSocket sock;
/**
* Constructor.
*
* @param sock UDP socket
* @param message DHCP packet content
*/
public DHCPTransaction(DatagramSocket sock, DatagramPacket message)
{
this.sock = sock;
this.message = message;
this.timer = new Timer();
}
/**
* Schedule a timer for retransmission.
*
* @throws Exception if message cannot be sent on the socket
*/
public void schedule() throws Exception
{
sock.send(message);
/* choose a random between [-1, 1] */
int rand = new Random().nextInt(2) - 1;
timer.schedule(new RetransmissionHandler(), (interval + rand) * 1000);
}
/**
* Cancel the transaction (i.e stop retransmission).
*/
public void cancel()
{
timer.cancel();
}
/**
* Set the maximum retransmission for a transaction.
*
* @param maxRetransmit maximum retransmission for this transaction
*/
public void setMaxRetransmit(int maxRetransmit)
{
this.maxRetransmit = maxRetransmit;
}
/**
* Set the fixed interval for retransmission.
*
* @param interval interval to set
*/
public void setInterval(int interval)
{
this.interval = interval;
}
/**
* A <tt>TimerTask</tt> that will handle retransmission of DHCP INFORM.
*
* @author Sebastien Vincent
*/
private class RetransmissionHandler
extends TimerTask
{
/**
* Thread entry point.
*/
@Override
public void run()
{
int rand = new Random().nextInt(2) - 1;
try
{
sock.send(message);
}
catch(Exception e)
{
logger.warn("Failed to send DHCP packet", e);
}
nbRetransmit++;
if(nbRetransmit < maxRetransmit)
{
timer.schedule(new RetransmissionHandler(),
(interval + rand) * 1000);
}
}
};
}
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