| // Copyright (C) 2012 The Android Open Source Project |
| // |
| // 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 com.google.gerrit.httpd; |
| |
| import com.google.gerrit.extensions.registration.DynamicSet; |
| import com.google.gerrit.server.plugins.Plugin; |
| import com.google.gerrit.server.plugins.StopPluginListener; |
| import com.google.inject.Inject; |
| import com.google.inject.Module; |
| import com.google.inject.Scopes; |
| import com.google.inject.Singleton; |
| import com.google.inject.internal.UniqueAnnotations; |
| import com.google.inject.servlet.ServletModule; |
| import java.io.IOException; |
| import java.util.Iterator; |
| import javax.servlet.Filter; |
| import javax.servlet.FilterChain; |
| import javax.servlet.FilterConfig; |
| import javax.servlet.ServletException; |
| import javax.servlet.ServletRequest; |
| import javax.servlet.ServletResponse; |
| |
| /** Filters all HTTP requests passing through the server. */ |
| public abstract class AllRequestFilter implements Filter { |
| public static Module module() { |
| return new ServletModule() { |
| @Override |
| protected void configureServlets() { |
| DynamicSet.setOf(binder(), AllRequestFilter.class); |
| DynamicSet.bind(binder(), AllRequestFilter.class) |
| .to(AllowRenderInFrameFilter.class) |
| .in(Scopes.SINGLETON); |
| |
| filter("/*").through(FilterProxy.class); |
| |
| bind(StopPluginListener.class) |
| .annotatedWith(UniqueAnnotations.create()) |
| .to(FilterProxy.class); |
| } |
| }; |
| } |
| |
| @Singleton |
| static class FilterProxy implements Filter, StopPluginListener { |
| private final DynamicSet<AllRequestFilter> filters; |
| |
| private DynamicSet<AllRequestFilter> initializedFilters; |
| private FilterConfig filterConfig; |
| |
| @Inject |
| FilterProxy(DynamicSet<AllRequestFilter> filters) { |
| this.filters = filters; |
| this.initializedFilters = new DynamicSet<>(); |
| this.filterConfig = null; |
| } |
| |
| /** |
| * Initializes a filter if needed |
| * |
| * @param filter The filter that should get initialized |
| * @return {@code true} iff filter is now initialized |
| * @throws ServletException if filter itself fails to init |
| */ |
| private synchronized boolean initFilterIfNeeded(AllRequestFilter filter) |
| throws ServletException { |
| boolean ret = true; |
| if (filters.contains(filter)) { |
| // Regardless of whether or not the caller checked filter's |
| // containment in initializedFilters, we better re-check as we're now |
| // synchronized. |
| if (!initializedFilters.contains(filter)) { |
| filter.init(filterConfig); |
| initializedFilters.add("gerrit", filter); |
| } |
| } else { |
| ret = false; |
| } |
| return ret; |
| } |
| |
| private synchronized void cleanUpInitializedFilters() { |
| Iterable<AllRequestFilter> filtersToCleanUp = initializedFilters; |
| initializedFilters = new DynamicSet<>(); |
| for (AllRequestFilter filter : filtersToCleanUp) { |
| if (filters.contains(filter)) { |
| initializedFilters.add("gerrit", filter); |
| } else { |
| filter.destroy(); |
| } |
| } |
| } |
| |
| @Override |
| public void doFilter(ServletRequest req, ServletResponse res, FilterChain last) |
| throws IOException, ServletException { |
| final Iterator<AllRequestFilter> itr = filters.iterator(); |
| new FilterChain() { |
| @Override |
| public void doFilter(ServletRequest req, ServletResponse res) |
| throws IOException, ServletException { |
| while (itr.hasNext()) { |
| AllRequestFilter filter = itr.next(); |
| // To avoid {@code synchronized} on the whole filtering (and |
| // thereby killing concurrency), we start the below disjunction |
| // with an unsynchronized check for containment. This |
| // unsynchronized check is always correct if no filters got |
| // initialized/cleaned concurrently behind our back. |
| // The case of concurrently initialized filters is saved by the |
| // call to initFilterIfNeeded. So that's fine too. |
| // The case of concurrently cleaned filters between the {@code if} |
| // condition and the call to {@code doFilter} is not saved by |
| // anything. If a filter is getting removed concurrently while |
| // another thread is in those two lines, doFilter might (but need |
| // not) fail. |
| // |
| // Since this failure only occurs if a filter is deleted |
| // (e.g.: a plugin reloaded) exactly when a thread is in those |
| // two lines, and it only breaks a single request, we're ok with |
| // it, given that this is really both really improbable and also |
| // the "proper" fix for it would basically kill concurrency of |
| // webrequests. |
| if (initializedFilters.contains(filter) || initFilterIfNeeded(filter)) { |
| filter.doFilter(req, res, this); |
| return; |
| } |
| } |
| last.doFilter(req, res); |
| } |
| }.doFilter(req, res); |
| } |
| |
| @Override |
| public void init(FilterConfig config) throws ServletException { |
| // Plugins that provide AllRequestFilters might get loaded later at |
| // runtime, long after this init method had been called. To allow to |
| // correctly init such plugins' AllRequestFilters, we keep the |
| // FilterConfig around, and reuse it to lazy init the AllRequestFilters. |
| filterConfig = config; |
| |
| for (AllRequestFilter f : filters) { |
| initFilterIfNeeded(f); |
| } |
| } |
| |
| @Override |
| public synchronized void destroy() { |
| Iterable<AllRequestFilter> filtersToDestroy = initializedFilters; |
| initializedFilters = new DynamicSet<>(); |
| for (AllRequestFilter filter : filtersToDestroy) { |
| filter.destroy(); |
| } |
| } |
| |
| @Override |
| public void onStopPlugin(Plugin plugin) { |
| // In order to allow properly garbage collection, we need to scrub |
| // initializedFilters clean of filters stemming from plugins as they |
| // get unloaded. |
| cleanUpInitializedFilters(); |
| } |
| } |
| |
| @Override |
| public void init(FilterConfig config) throws ServletException {} |
| |
| @Override |
| public void destroy() {} |
| } |