/*
* Created on Jul 18, 2005
* Created by Alon Rohter
* Copyright (C) 2005, 2006 Aelitis, All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program 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 for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
* AELITIS, SAS au capital de 46,603.30 euros
* 8 Allee Lenotre, La Grille Royale, 78600 Le Mesnil le Roi, France.
*
*/
package com.aelitis.azureus.core.peermanager.utils;
import java.util.*;
import org.gudy.azureus2.core3.util.SystemTime;
/**
* Handles incoming peer message counting/timing/stats in order to catch and block abusive peers.
*/
public class PeerMessageLimiter {
private final HashMap message_counts = new HashMap();
public PeerMessageLimiter() {
/*nothing*/
}
/**
* Add the reception of the given message to time-limited count.
* @param message_id message to count
* @param max_counts max counts allowed within the given time limit
* @param time_limit_ms time in ms that the count limiting applies
* @return true if the added count is within acceptable time limits, false if there have been too many counts
*/
public boolean countIncomingMessage( String message_id, int max_counts, int time_limit_ms ) {
CountData data = (CountData)message_counts.get( message_id );
if( data == null ) { //new message
data = new CountData( max_counts, time_limit_ms );
message_counts.put( message_id, data );
}
long now = SystemTime.getCurrentTime();
data.counts.addLast( new Long( now ) );
if( data.counts.size() > data.max_counts ) { //we've potentially reached our count limit
long cutoff = now - data.time_limit;
//prune out any expired counts
for( Iterator it = data.counts.iterator(); it.hasNext(); ) {
long time = ((Long)it.next()).longValue();
if( time < cutoff ) { //this count is older than the limit allows
it.remove(); //drop it
}
else { //still within limit
break;
}
}
if( data.counts.size() > data.max_counts ) { //too many counts within the time limit
return false; //return error
}
}
return true;
}
private static class CountData {
private final int max_counts;
private final int time_limit;
private final LinkedList counts = new LinkedList();
private CountData( int max_counts, int time_limit ) {
this.max_counts = max_counts;
this.time_limit = time_limit;
}
}
}