/*
* Zed Attack Proxy (ZAP) and its related class files.
*
* ZAP is an HTTP/HTTPS proxy for assessing web application security.
*
* Copyright 2013 ZAP development team
*
* 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.zaproxy.zap.control;
import java.io.IOException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* A {@code URLClassLoader} that search for classes and resources (first) in a given add-on file ({@code URL}). If a class or
* resource is not found, in the add-on file, the loading is delegated to the parent class loader. If not found in the parent
* class loader it will be searched in the dependencies (add-ons), if any.
*
* @see URLClassLoader
*/
public class AddOnClassLoader extends URLClassLoader {
private final ParentClassLoader parent;
private final List<AddOnClassLoader> childClassLoaders;
private List<AddOnClassLoader> dependencies;
private AddOnClassnames addOnClassnames;
/**
* Constructs a new {@code AddOnClassLoader} without dependencies on other add-ons.
*
* @param addOnFileUrl the URL to the add-on file that will be (first) used to load classes and resources
* @param parent the parent class loader for delegation
* @throws IllegalArgumentException if the {@code addOnFileUrl} or {@code parent} is {@code null}.
*/
public AddOnClassLoader(URL addOnFileUrl, ClassLoader parent) {
this(addOnFileUrl, parent, Collections.<AddOnClassLoader> emptyList(), AddOnClassnames.ALL_ALLOWED);
}
/**
* Constructs a new {@code AddOnClassLoader} without dependencies on other add-ons. Possibly restricting or allowing the
* loading of the given {@code addOnClassnames}, directly from this {@code AddOnClassLoader}.
*
*
* @param addOnFileUrl the URL to the add-on file that will be (first) used to load classes and resources
* @param parent the parent class loader for delegation
* @param addOnClassnames the classnames that can be loaded
* @throws IllegalArgumentException if the {@code addOnFileUrl} or {@code parent} is {@code null}.
* @since 2.4.3
*/
public AddOnClassLoader(URL addOnFileUrl, ClassLoader parent, AddOnClassnames addOnClassnames) {
this(addOnFileUrl, parent, Collections.<AddOnClassLoader> emptyList(), addOnClassnames);
}
/**
* Constructs a new {@code AddOnClassLoader} with the given {@code dependencies} which are used to find classes and
* resources when not found in the add-on or in {@code parent} ClassLoader.
*
* @param addOnFileUrl the URL to the add-on file that will be (first) used to load classes and resources
* @param parent the parent class loader for delegation
* @param dependencies the {@code AddOnClassLoader}s of the dependencies of the add-on
* @throws IllegalArgumentException if the {@code addOnFileUrl}, {@code parent} or {@code dependencies} is {@code null}.
* @since 2.4.0
*/
public AddOnClassLoader(URL addOnFileUrl, ClassLoader parent, List<AddOnClassLoader> dependencies) {
this(addOnFileUrl, parent, dependencies, AddOnClassnames.ALL_ALLOWED);
}
/**
* Constructs a new {@code AddOnClassLoader} with the given {@code dependencies} which are used to find classes and
* resources when not found in the add-on or in {@code parent} ClassLoader. Possibly restricting or allowing the loading of
* the given {@code addOnClassnames}, directly from this {@code AddOnClassLoader}.
*
* @param addOnFileUrl the URL to the add-on file that will be (first) used to load classes and resources
* @param parent the parent class loader for delegation
* @param dependencies the {@code AddOnClassLoader}s of the dependencies of the add-on
* @param addOnClassnames the classnames that can be loaded
* @throws IllegalArgumentException if the {@code addOnFileUrl}, {@code parent} or {@code dependencies} is {@code null}.
* @since 2.4.3
*/
public AddOnClassLoader(URL addOnFileUrl, ClassLoader parent, List<AddOnClassLoader> dependencies, AddOnClassnames addOnClassnames) {
super(new URL[] { addOnFileUrl }, null);
if (addOnFileUrl == null) {
throw new IllegalArgumentException("Parameter addOnFileUrl must not be null.");
}
if (parent == null) {
throw new IllegalArgumentException("Parameter parent must not be null.");
}
if (dependencies == null) {
throw new IllegalArgumentException("Parameter dependencies must not be null.");
}
this.parent = new ParentClassLoader(parent);
this.dependencies = dependencies.isEmpty() ? Collections.<AddOnClassLoader> emptyList() : new ArrayList<>(dependencies);
this.childClassLoaders = new ArrayList<>(2);
this.addOnClassnames = addOnClassnames;
}
/**
* Constructs a new {@code AddOnClassLoader} with the given {@code dependencies} which are used to find classes and
* resources when not found in the add-on or in {@code parent} {@code AddOnClassLoader}.
*
* @param parent the parent class loader for delegation
* @param dependencies the {@code AddOnClassLoader}s of the dependencies of the add-on
* @throws NullPointerException if {@code parent} is {@code null}.
* @throws IllegalArgumentException if the {@code addOnFileUrl} or {@code dependencies} is {@code null}.
* @since 2.4.0
*/
public AddOnClassLoader(AddOnClassLoader parent, List<AddOnClassLoader> dependencies) {
super(parent.getURLs(), null);
if (dependencies == null) {
throw new IllegalArgumentException("Parameter dependencies must not be null.");
}
parent.childClassLoaders.add(this);
this.parent = new ParentClassLoader(parent);
this.dependencies = dependencies.isEmpty() ? Collections.<AddOnClassLoader> emptyList() : new ArrayList<>(dependencies);
this.childClassLoaders = Collections.emptyList();
this.addOnClassnames = AddOnClassnames.ALL_ALLOWED;
}
/**
* Constructs a new {@code AddOnClassLoader} with the given {@code dependencies} which are used to find classes and
* resources when not found in the add-on or in {@code parent} {@code AddOnClassLoader}. Possibly restricting or allowing
* the loading of the given {@code classnames}, directly from this {@code AddOnClassLoader}.
*
* @param parent the parent class loader for delegation
* @param dependencies the {@code AddOnClassLoader}s of the dependencies of the add-on
* @param addOnClassnames the classnames that can be loaded
* @throws NullPointerException if {@code parent} is {@code null}.
* @throws IllegalArgumentException if the {@code addOnFileUrl}, {@code dependencies} or {@code packages} is {@code null}.
* @since 2.4.3
*/
public AddOnClassLoader(AddOnClassLoader parent, List<AddOnClassLoader> dependencies, AddOnClassnames addOnClassnames) {
super(parent.getURLs(), null);
if (dependencies == null) {
throw new IllegalArgumentException("Parameter dependencies must not be null.");
}
if (addOnClassnames == null) {
throw new IllegalArgumentException("Parameter addOnClassnames must not be null.");
}
parent.childClassLoaders.add(this);
this.parent = new ParentClassLoader(parent);
this.dependencies = dependencies.isEmpty() ? Collections.<AddOnClassLoader> emptyList() : new ArrayList<>(dependencies);
this.childClassLoaders = Collections.emptyList();
this.addOnClassnames = addOnClassnames;
}
/**
* Removes the given child class loader from the list of child class loaders.
*
* @param child the child class loader that will be removed
* @since 2.4.0
*/
public void removeChildClassLoader(AddOnClassLoader child) {
childClassLoaders.remove(child);
}
@Override
public void close() throws IOException {
for (AddOnClassLoader childClassLoader : childClassLoaders) {
childClassLoader.close();
}
super.close();
}
/**
* Clears the dependencies. Should be called when this class loader is no longer needed.
*
* @since 2.4.0
*/
public void clearDependencies() {
this.dependencies = Collections.emptyList();
}
@Override
protected Class<?> findClass(String name) throws ClassNotFoundException {
if (addOnClassnames.isAllowed(name)) {
try {
return findClassInAddOn(name);
} catch (ClassNotFoundException ignore) {
}
}
try {
return parent.loadClass(name, false);
} catch (ClassNotFoundException ignore) {
}
Class<?> clazz = findClassInDependencies(name);
if (clazz == null) {
throw new ClassNotFoundException();
}
return clazz;
}
private Class<?> findClassInAddOn(String name) throws ClassNotFoundException {
return super.findClass(name);
}
private Class<?> findClassInDependencies(String name) {
if (dependencies.isEmpty()) {
return null;
}
for (AddOnClassLoader addOnClassLoader : dependencies) {
try {
return addOnClassLoader.loadClass(name, false);
} catch (ClassNotFoundException ignore) {
}
}
return null;
}
@Override
public URL findResource(String name) {
URL url = findResourceInAddOn(name);
if (url == null) {
url = parent.getResource(name);
}
if (url == null) {
url = findResourceInDependencies(name);
}
return url;
}
/**
* Finds the resource with the specified name (only) in the add-on file.
*
* @param name the name of the resource
* @return a {@code URL} for the resource, or {@code null} if the resource could not be found, or if the loader is closed.
* @since 2.4.0
* @see #findResource(String)
*/
public URL findResourceInAddOn(String name) {
return super.findResource(name);
}
private URL findResourceInDependencies(String name) {
if (dependencies.isEmpty()) {
return null;
}
for (AddOnClassLoader addOnClassLoader : dependencies) {
URL url = addOnClassLoader.findResourceInAddOn(name);
if (url != null) {
return url;
}
}
return null;
}
/**
* Helper class that exposes the protected method {@code ClassLoader#loadClass(String, boolean)} to the class
* {@code AddOnClassLoader} (called in the method {@code AddOnClassLoader#findClass(String)}).
* <p>
* The class {@code AddOnClassLoader} needs access to the mentioned method because the class {@code AddOnLoader} makes use
* of the class {@code AddOnClassLoader} (in the method {@code AddOnLoader#loadClass(String)}), so it's called directly the
* method {@code ClassLoader#loadClass(String, boolean)} to prevent an infinite loop while loading the classes.
*
* @see AddOnLoader#loadClass(String)
* @see AddOnClassLoader#findClass(String)
* @see ClassLoader#loadClass(String, boolean)
*/
private static class ParentClassLoader extends ClassLoader {
public ParentClassLoader(ClassLoader classLoader) {
super(classLoader);
}
@Override
protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
return super.loadClass(name, resolve);
}
}
}