/*
 * 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.util;

import javax.servlet.http.HttpServletRequest;

/**
 * General purpose request parsing and encoding utility methods.
 *
 * @author Craig R. McClanahan
 * @author Tim Tye
 */
public final class RequestUtil {

    /**
     * Filter the specified message string for characters that are sensitive
     * in HTML.  This avoids potential attacks caused by including JavaScript
     * codes in the request URL that is often reported in error messages.
     *
     * @param message The message string to be filtered
     *
     * @return the filtered message
     */
    public static String filter(String message) {

        if (message == null) {
            return null;
        }

        char content[] = new char[message.length()];
        message.getChars(0, message.length(), content, 0);
        StringBuilder result = new StringBuilder(content.length + 50);
        for (int i = 0; i < content.length; i++) {
            switch (content[i]) {
            case '<':
                result.append("<");
                break;
            case '>':
                result.append(">");
                break;
            case '&':
                result.append("&");
                break;
            case '"':
                result.append(""");
                break;
            default:
                result.append(content[i]);
            }
        }
        return result.toString();
    }


    /**
     * Build an appropriate return value for
     * {@link HttpServletRequest#getRequestURL()} based on the provided
     * request object. Note that this will also work for instances of
     * {@link javax.servlet.http.HttpServletRequestWrapper}.
     *
     * @param request The request object for which the URL should be built
     *
     * @return The request URL for the given request object
     */
    public static StringBuffer getRequestURL(HttpServletRequest request) {
        StringBuffer url = new StringBuffer();
        String scheme = request.getScheme();
        int port = request.getServerPort();
        if (port < 0) {
            // Work around java.net.URL bug
            port = 80;
        }

        url.append(scheme);
        url.append("://");
        url.append(request.getServerName());
        if ((scheme.equals("http") && (port != 80))
            || (scheme.equals("https") && (port != 443))) {
            url.append(':');
            url.append(port);
        }
        url.append(request.getRequestURI());

        return url;
    }
}