/*
 * $Header: /home/cvs/jakarta-tomcat-catalina/catalina/src/share/org/apache/catalina/valves/RequestFilterValve.java,v 1.2 2003/09/02 21:22:03 remm Exp $
 * $Revision: 1.2 $
 * $Date: 2003/09/02 21:22:03 $
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999-2001 The Apache Software Foundation.  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 end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * 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 THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS 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
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 * 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */


package org.apache.catalina.valves;


import java.io.IOException;
import java.util.ArrayList;

import javax.servlet.ServletException;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletResponse;

import org.apache.catalina.Request;
import org.apache.catalina.Response;
import org.apache.catalina.ValveContext;
import org.apache.catalina.util.StringManager;
import org.apache.regexp.RE;
import org.apache.regexp.RESyntaxException;


/**
 * Implementation of a Valve that performs filtering based on comparing the
 * appropriate request property (selected based on which subclass you choose
 * to configure into your Container's pipeline) against a set of regular
 * expressions configured for this Valve.
 * <p>
 * This valve is configured by setting the <code>allow</code> and/or
 * <code>deny</code> properties to a comma-delimited list of regular
 * expressions (in the syntax supported by the jakarta-regexp library) to
 * which the appropriate request property will be compared.  Evaluation
 * proceeds as follows:
 * <ul>
 * <li>The subclass extracts the request property to be filtered, and
 *     calls the common <code>process()</code> method.
 * <li>If there are any deny expressions configured, the property will
 *     be compared to each such expression.  If a match is found, this
 *     request will be rejected with a "Forbidden" HTTP response.</li>
 * <li>If there are any allow expressions configured, the property will
 *     be compared to each such expression.  If a match is found, this
 *     request will be allowed to pass through to the next Valve in the
 *     current pipeline.</li>
 * <li>If one or more deny expressions was specified but no allow expressions,
 *     allow this request to pass through (because none of the deny
 *     expressions matched it).
 * <li>The request will be rejected with a "Forbidden" HTTP response.</li>
 * </ul>
 * <p>
 * This Valve may be attached to any Container, depending on the granularity
 * of the filtering you wish to perform.
 *
 * @author Craig R. McClanahan
 * @version $Revision: 1.2 $ $Date: 2003/09/02 21:22:03 $
 */

public abstract class RequestFilterValve
    extends ValveBase {


    // ----------------------------------------------------- Instance Variables


    /**
     * The comma-delimited set of <code>allow</code> expressions.
     */
    protected String allow = null;


    /**
     * The set of <code>allow</code> regular expressions we will evaluate.
     */
    protected RE allows[] = new RE[0];


    /**
     * The set of <code>deny</code> regular expressions we will evaluate.
     */
    protected RE denies[] = new RE[0];


    /**
     * The comma-delimited set of <code>deny</code> expressions.
     */
    protected String deny = null;


    /**
     * The descriptive information related to this implementation.
     */
    private static final String info =
        "org.apache.catalina.valves.RequestFilterValve/1.0";


    /**
     * The StringManager for this package.
     */
    protected static StringManager sm =
        StringManager.getManager(Constants.Package);


    // ------------------------------------------------------------- Properties


    /**
     * Return a comma-delimited set of the <code>allow</code> expressions
     * configured for this Valve, if any; otherwise, return <code>null</code>.
     */
    public String getAllow() {

        return (this.allow);

    }


    /**
     * Set the comma-delimited set of the <code>allow</code> expressions
     * configured for this Valve, if any.
     *
     * @param allow The new set of allow expressions
     */
    public void setAllow(String allow) {

        this.allow = allow;
        allows = precalculate(allow);

    }


    /**
     * Return a comma-delimited set of the <code>deny</code> expressions
     * configured for this Valve, if any; otherwise, return <code>null</code>.
     */
    public String getDeny() {

        return (this.deny);

    }


    /**
     * Set the comma-delimited set of the <code>deny</code> expressions
     * configured for this Valve, if any.
     *
     * @param deny The new set of deny expressions
     */
    public void setDeny(String deny) {

        this.deny = deny;
        denies = precalculate(deny);

    }


    /**
     * Return descriptive information about this Valve implementation.
     */
    public String getInfo() {

        return (info);

    }


    // --------------------------------------------------------- Public Methods


    /**
     * Extract the desired request property, and pass it (along with the
     * specified request and response objects) to the protected
     * <code>process()</code> method to perform the actual filtering.
     * This method must be implemented by a concrete subclass.
     *
     * @param request The servlet request to be processed
     * @param response The servlet response to be created
     * @param context The valve context used to invoke the next valve
     *  in the current processing pipeline
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    public abstract void invoke(Request request, Response response,
                                ValveContext context)
        throws IOException, ServletException;


    // ------------------------------------------------------ Protected Methods


    /**
     * Return an array of regular expression objects initialized from the
     * specified argument, which must be <code>null</code> or a comma-delimited
     * list of regular expression patterns.
     *
     * @param list The comma-separated list of patterns
     *
     * @exception IllegalArgumentException if one of the patterns has
     *  invalid syntax
     */
    protected RE[] precalculate(String list) {

        if (list == null)
            return (new RE[0]);
        list = list.trim();
        if (list.length() < 1)
            return (new RE[0]);
        list += ",";

        ArrayList reList = new ArrayList();
        while (list.length() > 0) {
            int comma = list.indexOf(',');
            if (comma < 0)
                break;
            String pattern = list.substring(0, comma).trim();
            try {
                reList.add(new RE(pattern));
            } catch (RESyntaxException e) {
                throw new IllegalArgumentException
                    (sm.getString("requestFilterValve.syntax", pattern));
            }
            list = list.substring(comma + 1);
        }

        RE reArray[] = new RE[reList.size()];
        return ((RE[]) reList.toArray(reArray));

    }


    /**
     * Perform the filtering that has been configured for this Valve, matching
     * against the specified request property.
     *
     * @param property The request property on which to filter
     * @param request The servlet request to be processed
     * @param response The servlet response to be processed
     * @param context The valve context used to invoke the next valve
     *  in the current processing pipeline
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    protected void process(String property,
                           Request request, Response response,
                           ValveContext context)
        throws IOException, ServletException {

        // Check the deny patterns, if any
        for (int i = 0; i < denies.length; i++) {
            if (denies[i].match(property)) {
                ServletResponse sres = response.getResponse();
                if (sres instanceof HttpServletResponse) {
                    HttpServletResponse hres = (HttpServletResponse) sres;
                    hres.sendError(HttpServletResponse.SC_FORBIDDEN);
                    return;
                }
            }
        }

        // Check the allow patterns, if any
        for (int i = 0; i < allows.length; i++) {
            if (allows[i].match(property)) {
                context.invokeNext(request, response);
                return;
            }
        }

        // Allow if denies specified but not allows
        if ((denies.length > 0) && (allows.length == 0)) {
            context.invokeNext(request, response);
            return;
        }

        // Deny this request
        ServletResponse sres = response.getResponse();
        if (sres instanceof HttpServletResponse) {
            HttpServletResponse hres = (HttpServletResponse) sres;
            hres.sendError(HttpServletResponse.SC_FORBIDDEN);
            return;
        }

    }


}
