/*
* @(#)RobinsonScanner.java 3/11/2004
*
* Copyright (c) 2004, 2005 jASEN.org
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the distribution.
*
* 3. The names of the authors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* 4. Any modification or additions to the software must be contributed back
* to the project.
*
* 5. Any investigation or reverse engineering of source code or binary to
* enable emails to bypass the filters, and hence inflict spam and or viruses
* onto users who use or do not use jASEN could subject the perpetrator to
* criminal and or civil liability.
*
* THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
* FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JASEN.ORG,
* OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
* OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
package org.jasen.plugins;
import java.io.InputStream;
import java.util.Properties;
import javax.mail.internet.MimeMessage;
import org.jasen.core.ProbabilityTestResult;
import org.jasen.core.calculators.ChiSquaredCalculator;
import org.jasen.core.engine.DiskMapStore;
import org.jasen.core.engine.Jasen;
import org.jasen.core.engine.JasenMap;
import org.jasen.error.JasenException;
import org.jasen.interfaces.JasenMapStore;
import org.jasen.interfaces.JasenMessage;
import org.jasen.interfaces.JasenPlugin;
import org.jasen.interfaces.JasenTestResult;
import org.jasen.interfaces.ParserData;
import org.jasen.interfaces.ReceivedHeaderParser;
/**
* <P>
* This scanner is the core spam detection system used in jASEN.
* </P>
* <p>
* It derives from the propositions put forward by Gary Robinson, and earlier from Paul Graham
* </p>
* @author Jason Polites
* @see <a href="http://www.paulgraham.com/spam.html">http://www.paulgraham.com/spam.html</a>
* @see <a href="http://www.garyrobinson.net/">http://www.garyrobinson.net/</a>
*/
public class RobinsonScanner implements JasenPlugin
{
private JasenMap map;
private int minTokens = 5;
private float defaultProb = 0.5f;
ChiSquaredCalculator calculator;
/**
*
*/
public RobinsonScanner() {
super ();
}
/* (non-Javadoc)
* @see org.jasen.interfaces.JasenPlugin#init(java.util.Properties)
*/
public void init(Properties properties) throws JasenException {
String mapPath = properties.getProperty("map-path");
InputStream in = this.getClass().getClassLoader().getResourceAsStream(mapPath);
if(in == null) {
throw new JasenException("Error locating token map in " + mapPath + ". Is this path in the classpath?");
}
// Load the token map...
String strMapStoreClass = properties.getProperty("map-store-class");
JasenMapStore store = null;
if(strMapStoreClass != null) {
try
{
store = (JasenMapStore)Class.forName(strMapStoreClass).newInstance();
}
catch (InstantiationException e)
{
throw new JasenException(e);
}
catch (IllegalAccessException e)
{
throw new JasenException(e);
}
catch (ClassNotFoundException e)
{
throw new JasenException(e);
}
}
else
{
store = new DiskMapStore();
}
map = store.load(in);
String strMinTokens = properties.getProperty("min-tokens");
String strDefaultProb = properties.getProperty("default-prob");
if(strMinTokens != null)
minTokens = Integer.parseInt(strMinTokens);
if(strDefaultProb != null)
defaultProb = Float.parseFloat(strDefaultProb);
calculator = new ChiSquaredCalculator();
}
/*
* (non-Javadoc)
* @see org.jasen.interfaces.JasenPlugin#destroy()
*/
public void destroy() throws JasenException {}
/*
* (non-Javadoc)
* @see org.jasen.interfaces.JasenPlugin#test(org.jasen.core.Jasen, javax.mail.internet.MimeMessage, org.jasen.interfaces.JasenMessage, org.jasen.interfaces.ParserData, org.jasen.interfaces.ReceivedHeaderParser)
*/
public JasenTestResult test(Jasen engine, MimeMessage rawMessage, JasenMessage parsedMessage, ParserData data, ReceivedHeaderParser parser) throws JasenException {
ProbabilityTestResult result = new ProbabilityTestResult();
if(data.getMessageTokens() == null || data.getMessageTokens().length <= minTokens) {
result.setProbability(defaultProb);
}
else
{
double prob = calculator.confirmHypothesis(data.getMessageTokens(), map);
result.setProbability((float)prob);
}
return result;
}
}