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Tomcat example source code file (RequestFilterValve.java)

This example Tomcat source code file (RequestFilterValve.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

arraylist, http, illegalargumentexception, io, ioexception, pattern, pattern, patternsyntaxexception, regex, request, request, response, response, servlet, servletexception, servletexception, string, string, util, valvebase

The Tomcat RequestFilterValve.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package org.apache.catalina.valves;


import java.io.IOException;
import java.util.ArrayList;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

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

import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.util.StringManager;

/**
 * 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 and/or
 * <code>deny 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() 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.
 * </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: 467222 $ $Date: 2006-10-24 05:17:11 +0200 (mar., 24 oct. 2006) $
 */

public abstract class RequestFilterValve
    extends ValveBase {


    // ----------------------------------------------------- Class Variables


    /**
     * 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);


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


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


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


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


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


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


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

        return (this.allow);

    }


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

        return (this.deny);

    }


    /**
     * Set the comma-delimited set of the <code>deny 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() 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
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    public abstract void invoke(Request request, Response response)
        throws IOException, ServletException;


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


    /**
     * Return an array of regular expression objects initialized from the
     * specified argument, which must be <code>null 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 Pattern[] precalculate(String list) {

        if (list == null)
            return (new Pattern[0]);
        list = list.trim();
        if (list.length() < 1)
            return (new Pattern[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(Pattern.compile(pattern));
            } catch (PatternSyntaxException e) {
                IllegalArgumentException iae = new IllegalArgumentException
                    (sm.getString("requestFilterValve.syntax", pattern));
                iae.initCause(e);
                throw iae;
            }
            list = list.substring(comma + 1);
        }

        Pattern reArray[] = new Pattern[reList.size()];
        return ((Pattern[]) 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
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet error occurs
     */
    protected void process(String property,
                           Request request, Response response)
        throws IOException, ServletException {

        // Check the deny patterns, if any
        for (int i = 0; i < denies.length; i++) {
            if (denies[i].matcher(property).matches()) {
                response.sendError(HttpServletResponse.SC_FORBIDDEN);
                return;
            }
        }

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

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

        // Deny this request
        response.sendError(HttpServletResponse.SC_FORBIDDEN);

    }


}

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