/**
* 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.marmotta.platform.core.servlet;
import org.apache.marmotta.platform.core.api.config.ConfigurationService;
import org.apache.marmotta.platform.core.api.modules.MarmottaHttpFilter;
import org.apache.marmotta.platform.core.api.modules.ModuleService;
import org.slf4j.Logger;
import javax.enterprise.inject.Any;
import javax.enterprise.inject.Instance;
import javax.inject.Inject;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.io.Serializable;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
/**
* This filter is used by KiWi for initialisation of the KiWi system on startup of the server. It does not perform
* any actual filtering. For this purpose, a listener would have been better, but CDI in Jetty does not support
* injection into listeners, so we "abuse" a filter for this purpose. Filters always get initialised before servlets,
* so by adding the KiWiFilter as the first entry into web.xml, we can ensure that the KiWi initialisation is done
* before everything else.
* <p/>
* User: sschaffe
*/
public class MarmottaResourceFilter implements Filter {
@Inject
private Logger log;
@Inject
private ConfigurationService configurationService;
@Inject
private ModuleService moduleService;
@Inject @Any
private Instance<MarmottaHttpFilter> filters;
private List<MarmottaHttpFilter> filterList;
/**
* Called by the web container to indicate to a filter that it is being placed into
* service. The servlet container calls the init method exactly once after instantiating the
* filter. The init method must complete successfully before the filter is asked to do any
* filtering work. <br><br>
* <p/>
* The web container cannot place the filter into service if the init method either<br>
* 1.Throws a ServletException <br>
* 2.Does not return within a time period defined by the web container
*/
@Override
public void init(FilterConfig filterConfig) throws ServletException {
log.info("Apache Marmotta Resource Filter {} starting up ... ", configurationService.getConfiguration("kiwi.version"));
// initialise filter chain and sort it according to priority
this.filterList = new ArrayList<MarmottaHttpFilter>();
for(MarmottaHttpFilter filter : filters) {
try {
filter.init(filterConfig);
filterList.add(filter);
log.debug("module {}: registered filter {}", moduleService.getModuleConfiguration(filter.getClass()).getModuleName(), filter.getClass().getCanonicalName());
} catch (ServletException ex) {
log.error("could not instantiate filter {}, servlet exception during initialisation ({})",filter.getClass(),ex.getMessage());
}
}
Collections.sort(filterList,new FilterComparator());
}
/**
* The <code>doFilter</code> method of the Filter is called by the container
* each time a request/response pair is passed through the chain due
* to a client request for a resource at the end of the chain. The FilterChain passed in to this
* method allows the Filter to pass on the request and response to the next entity in the
* chain.<p>
* A typical implementation of this method would follow the following pattern:- <br>
* 1. Examine the request<br>
* 2. Optionally wrap the request object with a custom implementation to
* filter content or headers for input filtering <br>
* 3. Optionally wrap the response object with a custom implementation to
* filter content or headers for output filtering <br>
* 4. a) <strong>Either</strong> invoke the next entity in the chain using the FilterChain object (<code>chain.doFilter()</code>), <br>
* * 4. b) <strong>or</strong> not pass on the request/response pair to the next entity in the filter chain to block the request processing<br>
* * 5. Directly set headers on the response after invocation of the next entity in the filter chain.
*/
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
URL url = null;
String prefix = null, path = null;
if (request instanceof HttpServletRequest) {
url = new URL(((HttpServletRequest)request).getRequestURL().toString());
prefix = ((HttpServletRequest)request).getContextPath();
if(url.getPath().startsWith(prefix)) {
path = url.getPath().substring(prefix.length());
}
}
new LMFFilterChain(path,chain).doFilter(request,response);
}
/**
* Called by the web container to indicate to a filter that it is being taken out of service. This
* method is only called once all threads within the filter's doFilter method have exited or after
* a timeout period has passed. After the web container calls this method, it will not call the
* doFilter method again on this instance of the filter. <br><br>
* <p/>
* This method gives the filter an opportunity to clean up any resources that are being held (for
* example, memory, file handles, threads) and make sure that any persistent state is synchronized
* with the filter's current state in memory.
*/
@Override
public void destroy() {
for(MarmottaHttpFilter filter : filterList) {
filter.destroy();
}
}
/**
* A special filter chain that implements the LMFHttpFilter calls
*/
private class LMFFilterChain implements FilterChain {
private Iterator<MarmottaHttpFilter> filters;
private String path;
private FilterChain originalChain;
LMFFilterChain(String path, FilterChain originalChain) {
this.path = path;
this.filters = filterList.iterator();
this.originalChain = originalChain;
}
@Override
public void doFilter(ServletRequest request, ServletResponse response) throws IOException, ServletException {
if(filters.hasNext()) {
MarmottaHttpFilter filter = filters.next();
if(path.matches(filter.getPattern())) {
filter.doFilter(request,response,this);
} else {
doFilter(request,response);
}
} else {
originalChain.doFilter(request,response);
}
}
}
private static class FilterComparator implements Comparator<MarmottaHttpFilter>, Serializable {
private static final long serialVersionUID = -7264645592168345092L;
/**
* Compares its two arguments for order. Returns a negative integer,
* zero, or a positive integer as the first argument is less than, equal
* to, or greater than the second.<p>
* <p/>
*
* @param o1 the first object to be compared.
* @param o2 the second object to be compared.
* @return a negative integer, zero, or a positive integer as the
* first argument is less than, equal to, or greater than the
* second.
* @throws ClassCastException if the arguments' types prevent them from
* being compared by this comparator.
*/
@Override
public int compare(MarmottaHttpFilter o1, MarmottaHttpFilter o2) {
if(o1.getPriority() < o2.getPriority())
return -1;
else if(o1.getPriority() > o2.getPriority()) return 1;
else
return 0;
}
}
}