/*
* Copyright (C) 2015 Red Hat, Inc. and/or its affiliates.
*
* Licensed 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.jboss.errai.common.server;
import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.jboss.errai.common.client.api.Assert;
/**
* This servlet provides a cache manifest file specific to the requesting user
* agent. It responds to .appcache requests and dispatches to user agent
* specific appcache.manifest files (i.e. safari.appcache.manifest). These files
* are generated at compile time by a dedicated linker. See the Errai reference
* guide for details on how to activate this linker.
*
* @author Christian Sadilek <csadilek@redhat.com>
*/
@WebServlet(urlPatterns = "*.appcache")
public class CacheManifestServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private static final String MANIFEST_FILE_EXTENSION = ".appcache.manifest";
// Lazily populated cache for user agent names for which a manifest file
// exists, on a per module basis
private final Map<String, Set<String>> manifestsPerModule = new ConcurrentHashMap<String, Set<String>>();
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
final Pattern pattern = Pattern.compile("/([a-zA-Z0-9_]+)/errai.appcache");
final Matcher matcher = pattern.matcher(req.getServletPath());
if (!matcher.find()) {
resp.sendError(HttpServletResponse.SC_NOT_FOUND);
return;
}
final String module = matcher.group(1);
String userAgentManifestPath = null;
final String referrer = req.getHeader("referer");
if (referrer != null && referrer.contains("gwt.codesvr")) {
// Serve an empty manifest in development mode. This is not reliable as
// some browser won't send the referer header when requesting the
// manifest. In that case we simply return a 404 (the manifest is not
// needed in dev mode anyway but we try to avoid the error, if possible).
userAgentManifestPath = "/" + module + "/dev.appcache.manifest";
}
else {
userAgentManifestPath = "/" + module + "/" + getUserAgentManifestName(req, module);
}
resp.setHeader("Cache-Control", "no-cache");
resp.setHeader("Pragma", "no-cache");
resp.setContentType("text/cache-manifest");
req.getRequestDispatcher(userAgentManifestPath).forward(req, resp);
}
private String getUserAgentManifestName(HttpServletRequest req, String module) {
final String userAgentHeader = req.getHeader("user-agent").toLowerCase();
String agentPrefix = "";
// Do not change the order of these checks. To verify this, compile a
// nocache.js file in pretty mode and compare the corresponding client-side
// logic provided by GWT. Tested with GWT 2.5 and 2.6.
if (userAgentHeader.contains("opera") && manifestExists("opera", module)) {
agentPrefix = "opera";
}
else if (userAgentHeader.contains("webkit") && manifestExists("safari", module)) {
agentPrefix = "safari";
}
else if (userAgentHeader.contains("msie 10") && manifestExists("ie10", module)) {
agentPrefix = "ie10";
}
else if (userAgentHeader.contains("msie 10") && manifestExists("ie9", module)) {
agentPrefix = "ie9";
}
else if (userAgentHeader.contains("msie 9") && manifestExists("ie9", module)) {
agentPrefix = "ie9";
}
else if (userAgentHeader.contains("msie 8") && manifestExists("ie8", module)) {
agentPrefix = "ie8";
}
else if (userAgentHeader.contains("msie") && manifestExists("ie6", module)) {
agentPrefix = "ie6";
}
else if (userAgentHeader.contains("msie") && manifestExists("ie8", module)) {
agentPrefix = "ie8";
}
else if (userAgentHeader.contains("gecko") && manifestExists("gecko1_8", module)) {
agentPrefix = "gecko1_8";
}
return agentPrefix + MANIFEST_FILE_EXTENSION;
}
/**
* Returns the set of user agent names for which a manifest file exists in the
* provided module.
*
* @param module
* the name of the GWT module. Not null.
* @return the user agent names for which a manifest file exists.
*/
private Set<String> getManifestsForModule(String module) {
Assert.notNull(module);
Set<String> manifests = manifestsPerModule.get(module);
if (manifests == null) {
final String path = getServletContext().getRealPath(module);
final File[] manifestFiles = new File(path).listFiles(new FilenameFilter() {
@Override
public boolean accept(File dir, String name) {
return name.endsWith(MANIFEST_FILE_EXTENSION);
}
});
manifests = new HashSet<String>();
if (manifestFiles != null) {
for (final File manifestFile : manifestFiles) {
final String name = manifestFile.getName();
manifests.add(name.replace(MANIFEST_FILE_EXTENSION, ""));
}
}
manifestsPerModule.put(module, manifests);
}
return manifests;
}
/**
* Checks if a user agent specific manifest file exists for the provided
* module.
*
* @param userAgent
* the user agent
* @param module
* the GWT module name
* @return true if the manifest exists, otherwise false.
*/
private boolean manifestExists(String userAgent, String module) {
return getManifestsForModule(module).contains(userAgent);
}
}