org.jwall.web.audit.session.HeuristicSessionTracker Maven / Gradle / Ivy

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/*
 *  Copyright (C) 2007-2014 Christian Bockermann 
 *
 *  This file is part of the  web-audit  library.
 *
 *  web-audit library 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 3 of the License, or
 *  (at your option) any later version.
 *
 *  The  web-audit  library 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, see .
 *
 */
package org.jwall.web.audit.session;

import java.util.HashMap;
import java.util.LinkedList;

import org.jwall.web.audit.AuditEvent;
import org.jwall.web.audit.ModSecurity;


/**
 * 
 * This heuristic session-tracker implements the session-algorithm used by
 * most popular web-statistic tools, e.g. WUM.
 *
 * @author Christian Bockermann <[email protected]>
 * 
 */
public class HeuristicSessionTracker 
extends AbstractSessionTracker 
{
	/**
	 * This constructor creates a session-tracker based on heuristics.
	 * Key to the session is simply the ip-address of the requests.
	 *
	 * @param sessionTime
	 */
	public HeuristicSessionTracker(long sessionTime){
		super( sessionTime );
		sessionTimeOut = sessionTime;

		//
		// this hash stores lists of sessions by ip-address, user-agent and start-date
		// when one session ends (times out), another is created an enqueued to the
		// list identified by (ip-address,user-agent)
		//
		activeSessions = new HashMap();

		//
		// we store a list of all timed-out sessions
		//
		timedOutSessions = new LinkedList();
	}



	/**
	 * 
	 * Since this tracker simply relies on the remote address as session key, this 
	 * method will just return the event's sender-address.
	 * 
	 * @param evt The AuditEvent to extract a key-id from.
	 * @return A string with the ip-address of the event to be used as a session-id.
	 * 
	 */
	public String extractKey( AuditEvent evt ){
		try {

			StringBuffer msg = new StringBuffer();

			String addr = evt.get( ModSecurity.REMOTE_ADDR );
			msg.append( addr );

			String ua = evt.get( ModSecurity.REQUEST_HEADERS + ":" + HttpProtocol.REQUEST_HEADER_USER_AGENT );

			if( ua != null )
				msg.append( ua );

			return msg.toString();

		} catch (Exception e ){
			return evt.get( ModSecurity.REMOTE_ADDR );
		}
	}

	public String toString(){
		return "HeuristicSessionTracker["+this.sessionTimeOut+"]";
	}
}