BaseExceptionRenderer.java

/*
 *  This file is part of the Wayback archival access software
 *   (http://archive-access.sourceforge.net/projects/wayback/).
 *
 *  Licensed to the Internet Archive (IA) by one or more individual 
 *  contributors. 
 *
 *  The IA 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.archive.wayback.exception;

import java.io.IOException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

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

import org.archive.wayback.ExceptionRenderer;
import org.archive.wayback.ResultURIConverter;
import org.archive.wayback.core.UIResults;
import org.archive.wayback.core.WaybackRequest;

/**
 * Default implementation responsible for outputting error responses to users
 * for expected failure situations, for both Replay and Query requests.
 * 
 * Has logic to return errors as XML, if in query mode, and if user requested 
 * XML.
 * 
 * Has logic to render errors as CSS, Javascript, and blank images, if the
 * request is Replay mode, embedded, and of an obvious type from the request URL
 *
 * @author brad
 * @version $Date$, $Revision$
 */
public class BaseExceptionRenderer implements ExceptionRenderer {
	private String xmlErrorJsp = "/WEB-INF/exception/XMLError.jsp";
	private String errorJsp = "/WEB-INF/exception/HTMLError.jsp";
	private String imageErrorJsp = "/WEB-INF/exception/HTMLError.jsp";
	private String javascriptErrorJsp = "/WEB-INF/exception/JavaScriptError.jsp";
	private String cssErrorJsp = "/WEB-INF/exception/CSSError.jsp";

	protected final Pattern IMAGE_REGEX = Pattern
			.compile(".*\\.(jpg|jpeg|gif|png|bmp|tiff|tif)$");

	/* ERROR HANDLING RESPONSES: */

	protected boolean requestIsEmbedded(HttpServletRequest httpRequest,
			WaybackRequest wbRequest) {
		// without a wbRequest, assume it is not embedded: send back HTML
		if (wbRequest == null) {
			return false;
		}
		String referer = wbRequest.getRefererUrl();
		return (referer != null && referer.length() > 0);
	}

	protected boolean requestIsImage(HttpServletRequest httpRequest,
			WaybackRequest wbRequest) {
		if (wbRequest == null) {
			return false;
		}
		if(wbRequest.isIMGContext()) {
			return true;
		}
		String requestUrl = wbRequest.getRequestUrl();
		if (requestUrl == null)
			return false;
		Matcher matcher = IMAGE_REGEX.matcher(requestUrl);
		return (matcher != null && matcher.matches());
	}

	protected boolean requestIsJavascript(HttpServletRequest httpRequest,
			WaybackRequest wbRequest) {
		if (wbRequest == null) {
			return false;
		}
		if(wbRequest.isJSContext()) {
			return true;
		}
		String requestUrl = wbRequest.getRequestUrl();
		return (requestUrl != null) && requestUrl.endsWith(".js");
	}

	protected boolean requestIsCSS(HttpServletRequest httpRequest,
			WaybackRequest wbRequest) {
		if (wbRequest == null) {
			return false;
		}
		if(wbRequest.isCSSContext()) {
			return true;
		}
		String requestUrl = wbRequest.getRequestUrl();
		return (requestUrl != null) && requestUrl.endsWith(".css");
	}

	public void renderException(HttpServletRequest httpRequest,
			HttpServletResponse httpResponse, WaybackRequest wbRequest,
			WaybackException exception, ResultURIConverter uriConverter)
		throws ServletException, IOException {

		httpRequest.setAttribute("exception", exception);
		UIResults uiResults = new UIResults(wbRequest,uriConverter,exception);
		boolean handled = false;
		if((wbRequest != null) && !wbRequest.isReplayRequest()) {

			if(wbRequest.isXMLMode()) {
				uiResults.forward(httpRequest, httpResponse, xmlErrorJsp);
				handled = true;
			}

		} else if (requestIsEmbedded(httpRequest, wbRequest)) {
		
			// try to not cause client errors by sending the HTML response if
			// this request is ebedded, and is obviously one of the special 
			// types:
			handled = true;

			if (requestIsJavascript(httpRequest, wbRequest)) {

				uiResults.forward(httpRequest, httpResponse,
						javascriptErrorJsp);

			} else if (requestIsCSS(httpRequest, wbRequest)) {

				uiResults.forward(httpRequest, httpResponse, cssErrorJsp);

			} else if (requestIsImage(httpRequest, wbRequest)) {

				uiResults.forward(httpRequest, httpResponse, imageErrorJsp);

			} else {
				handled = false;
			}
		}
		if(!handled) {
			uiResults.forward(httpRequest, httpResponse, errorJsp);
		}
	}

	public String getErrorJsp() {
		return errorJsp;
	}

	public void setErrorJsp(String errorJsp) {
		this.errorJsp = errorJsp;
	}

	/**
	 * @return the xmlErrorJsp
	 */
	public String getXmlErrorJsp() {
		return xmlErrorJsp;
	}

	/**
	 * @param xmlErrorJsp the xmlErrorJsp to set
	 */
	public void setXmlErrorJsp(String xmlErrorJsp) {
		this.xmlErrorJsp = xmlErrorJsp;
	}

	public String getImageErrorJsp() {
		return imageErrorJsp;
	}

	public void setImageErrorJsp(String imageErrorJsp) {
		this.imageErrorJsp = imageErrorJsp;
	}

	public String getJavascriptErrorJsp() {
		return javascriptErrorJsp;
	}

	public void setJavascriptErrorJsp(String javascriptErrorJsp) {
		this.javascriptErrorJsp = javascriptErrorJsp;
	}

	public String getCssErrorJsp() {
		return cssErrorJsp;
	}

	public void setCssErrorJsp(String cssErrorJsp) {
		this.cssErrorJsp = cssErrorJsp;
	}
}