Add support for HTTP plugins

Plugins may contribute to the /plugins/NAME/ URL space by providing
a ServletModule in the manifest using Gerrit-HttpModule and binding
servlets and filters using Guice bindings.

All names are relative to the plugin's directory, so

  serve("/").with(IndexServlet.class);

will handle /plugins/NAME/ and not "/" on the server. This makes a
plugin automatically relocatable to match its SSH command name or
the name in $site_dir/plugins.

Change-Id: I17e3007f0310d2bf4989d652f18864a77c5d5f2e

gerrit-server/src/main/java/com/google/gerrit/server/plugins/Plugin.java

@@ -20,6 +20,7 @@ import com.google.inject.AbstractModule;
 import com.google.inject.Guice;
 import com.google.inject.Injector;
 import com.google.inject.Module;
+import com.google.inject.servlet.GuiceFilter;
 
 import org.eclipse.jgit.storage.file.FileSnapshot;
 
@@ -30,15 +31,24 @@ import java.util.jar.Manifest;
 import javax.annotation.Nullable;
 
 public class Plugin {
+  static {
+    // Guice logs warnings about multiple injectors being created.
+    // Silence this in case HTTP plugins are used.
+    java.util.logging.Logger.getLogger(GuiceFilter.class.getName())
+        .setLevel(java.util.logging.Level.OFF);
+  }
+
   private final String name;
   private final File jar;
   private final Manifest manifest;
   private final FileSnapshot snapshot;
   private Class<? extends Module> sysModule;
   private Class<? extends Module> sshModule;
+  private Class<? extends Module> httpModule;
 
   private Injector sysInjector;
   private Injector sshInjector;
+  private Injector httpInjector;
   private LifecycleManager manager;
 
   public Plugin(String name,
@@ -46,13 +56,15 @@ public class Plugin {
       Manifest manifest,
       FileSnapshot snapshot,
       @Nullable Class<? extends Module> sysModule,
-      @Nullable Class<? extends Module> sshModule) {
+      @Nullable Class<? extends Module> sshModule,
+      @Nullable Class<? extends Module> httpModule) {
     this.name = name;
     this.jar = jar;
     this.manifest = manifest;
     this.snapshot = snapshot;
     this.sysModule = sysModule;
     this.sshModule = sshModule;
+    this.httpModule = httpModule;
   }
 
   File getJar() {
@@ -90,6 +102,13 @@ public class Plugin {
       manager.add(sshInjector);
     }
 
+    if (httpModule != null && env.hasHttpModule()) {
+      httpInjector = sysInjector.createChildInjector(
+          env.getHttpModule(),
+          sysInjector.getInstance(httpModule));
+      manager.add(httpInjector);
+    }
+
     manager.start();
     env.onStartPlugin(this);
   }
@@ -113,6 +132,7 @@ public class Plugin {
       manager = null;
       sysInjector = null;
       sshInjector = null;
+      httpInjector = null;
     }
   }
 
@@ -121,6 +141,11 @@ public class Plugin {
     return sshInjector;
   }
 
+  @Nullable
+  public Injector getHttpInjector() {
+    return httpInjector;
+  }
+
   public void add(final RegistrationHandle handle) {
     add(new LifecycleListener() {
       @Override

gerrit-server/src/main/java/com/google/gerrit/server/plugins/PluginGuiceEnvironment.java

@@ -45,6 +45,7 @@ public class PluginGuiceEnvironment {
   private final List<StartPluginListener> listeners;
   private Module sysModule;
   private Module sshModule;
+  private Module httpModule;
 
   @Inject
   PluginGuiceEnvironment(Injector sysInjector, CopyConfigModule ccm) {
@@ -84,6 +85,19 @@ public class PluginGuiceEnvironment {
     return sshModule;
   }
 
+  public void setHttpInjector(Injector httpInjector) {
+    httpModule = copy(httpInjector);
+    listeners.addAll(getListeners(httpInjector));
+  }
+
+  boolean hasHttpModule() {
+    return httpModule != null;
+  }
+
+  Module getHttpModule() {
+    return httpModule;
+  }
+
   void onStartPlugin(Plugin plugin) {
     for (StartPluginListener l : listeners) {
       l.onStartPlugin(plugin);
@@ -126,15 +140,74 @@ public class PluginGuiceEnvironment {
 
   private static boolean shouldCopy(Key<?> key) {
     Class<?> type = key.getTypeLiteral().getRawType();
-    if (type == LifecycleListener.class) {
+    if (LifecycleListener.class.isAssignableFrom(type)) {
       return false;
     }
-    if (type == StartPluginListener.class) {
+    if (StartPluginListener.class.isAssignableFrom(type)) {
       return false;
     }
-    if ("org.apache.sshd.server.Command".equals(type.getName())) {
+
+    if (type.getName().startsWith("com.google.inject.")) {
+      return false;
+    }
+
+    if (is("org.apache.sshd.server.Command", type)) {
+      return false;
+    }
+
+    if (is("javax.servlet.Filter", type)) {
+      return false;
+    }
+    if (is("javax.servlet.ServletContext", type)) {
+      return false;
+    }
+    if (is("javax.servlet.ServletRequest", type)) {
+      return false;
+    }
+    if (is("javax.servlet.ServletResponse", type)) {
+      return false;
+    }
+    if (is("javax.servlet.http.HttpServlet", type)) {
+      return false;
+    }
+    if (is("javax.servlet.http.HttpServletRequest", type)) {
+      return false;
+    }
+    if (is("javax.servlet.http.HttpServletResponse", type)) {
+      return false;
+    }
+    if (is("javax.servlet.http.HttpSession", type)) {
+      return false;
+    }
+    if (Map.class.isAssignableFrom(type)
+        && key.getAnnotationType() != null
+        && "com.google.inject.servlet.RequestParameters"
+            .equals(key.getAnnotationType().getName())) {
+      return false;
+    }
+    if (type.getName().startsWith("com.google.gerrit.httpd.GitOverHttpServlet$")) {
       return false;
     }
     return true;
   }
+
+  private static boolean is(String name, Class<?> type) {
+    Class<?> p = type;
+    while (p != null) {
+      if (name.equals(p.getName())) {
+        return true;
+      }
+      p = p.getSuperclass();
+    }
+
+    Class<?>[] interfaces = type.getInterfaces();
+    if (interfaces != null) {
+      for (Class<?> i : interfaces) {
+        if (is(name, i)) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
 }

gerrit-server/src/main/java/com/google/gerrit/server/plugins/PluginLoader.java

@@ -245,6 +245,7 @@ public class PluginLoader implements LifecycleListener {
     Attributes main = manifest.getMainAttributes();
     String sysName = main.getValue("Gerrit-Module");
     String sshName = main.getValue("Gerrit-SshModule");
+    String httpName = main.getValue("Gerrit-HttpModule");
 
     URL[] urls = {jarFile.toURI().toURL()};
     ClassLoader parentLoader = PluginLoader.class.getClassLoader();
@@ -252,7 +253,9 @@ public class PluginLoader implements LifecycleListener {
 
     Class<? extends Module> sysModule = load(sysName, pluginLoader);
     Class<? extends Module> sshModule = load(sshName, pluginLoader);
-    return new Plugin(name, jarFile, manifest, snapshot, sysModule, sshModule);
+    Class<? extends Module> httpModule = load(httpName, pluginLoader);
+    return new Plugin(name, jarFile, manifest, snapshot,
+        sysModule, sshModule, httpModule);
   }
 
   private Class<? extends Module> load(String name, ClassLoader pluginLoader)