/*
* Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package java.lang.reflect;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import jdk.internal.loader.BootLoader;
import jdk.internal.module.Modules;
import jdk.internal.misc.Unsafe;
import jdk.internal.misc.VM;
import jdk.internal.reflect.CallerSensitive;
import jdk.internal.reflect.Reflection;
import jdk.internal.loader.ClassLoaderValue;
import sun.reflect.misc.ReflectUtil;
import sun.security.action.GetPropertyAction;
import sun.security.util.SecurityConstants;
/**
*
* {@code Proxy} provides static methods for creating objects that act like instances
* of interfaces but allow for customized method invocation.
* To create a proxy instance for some interface {@code Foo}:
* <pre>{@code
* InvocationHandler handler = new MyInvocationHandler(...);
* Foo f = (Foo) Proxy.newProxyInstance(Foo.class.getClassLoader(),
* new Class<?>[] { Foo.class },
* handler);
* }</pre>
*
* <p>
* A <em>proxy class</em> is a class created at runtime that implements a specified
* list of interfaces, known as <em>proxy interfaces</em>. A <em>proxy instance</em>
* is an instance of a proxy class.
*
* Each proxy instance has an associated <i>invocation handler</i>
* object, which implements the interface {@link InvocationHandler}.
* A method invocation on a proxy instance through one of its proxy
* interfaces will be dispatched to the {@link InvocationHandler#invoke
* invoke} method of the instance's invocation handler, passing the proxy
* instance, a {@code java.lang.reflect.Method} object identifying
* the method that was invoked, and an array of type {@code Object}
* containing the arguments. The invocation handler processes the
* encoded method invocation as appropriate and the result that it
* returns will be returned as the result of the method invocation on
* the proxy instance.
*
* <p>A proxy class has the following properties:
*
* <ul>
* <li>The unqualified name of a proxy class is unspecified. The space
* of class names that begin with the string {@code "$Proxy"}
* should be, however, reserved for proxy classes.
*
* <li>The package and module in which a proxy class is defined is specified
* <a href="#membership">below</a>.
*
* <li>A proxy class is <em>final and non-abstract</em>.
*
* <li>A proxy class extends {@code java.lang.reflect.Proxy}.
*
* <li>A proxy class implements exactly the interfaces specified at its
* creation, in the same order. Invoking {@link Class#getInterfaces getInterfaces}
* on its {@code Class} object will return an array containing the same
* list of interfaces (in the order specified at its creation), invoking
* {@link Class#getMethods getMethods} on its {@code Class} object will return
* an array of {@code Method} objects that include all of the
* methods in those interfaces, and invoking {@code getMethod} will
* find methods in the proxy interfaces as would be expected.
*
* <li>The {@link java.security.ProtectionDomain} of a proxy class
* is the same as that of system classes loaded by the bootstrap class
* loader, such as {@code java.lang.Object}, because the code for a
* proxy class is generated by trusted system code. This protection
* domain will typically be granted {@code java.security.AllPermission}.
*
* <li>The {@link Proxy#isProxyClass Proxy.isProxyClass} method can be used
* to determine if a given class is a proxy class.
* </ul>
*
* <p>A proxy instance has the following properties:
*
* <ul>
* <li>Given a proxy instance {@code proxy} and one of the
* interfaces, {@code Foo}, implemented by its proxy class, the
* following expression will return true:
* <pre>
* {@code proxy instanceof Foo}
* </pre>
* and the following cast operation will succeed (rather than throwing
* a {@code ClassCastException}):
* <pre>
* {@code (Foo) proxy}
* </pre>
*
* <li>Each proxy instance has an associated invocation handler, the one
* that was passed to its constructor. The static
* {@link Proxy#getInvocationHandler Proxy.getInvocationHandler} method
* will return the invocation handler associated with the proxy instance
* passed as its argument.
*
* <li>An interface method invocation on a proxy instance will be
* encoded and dispatched to the invocation handler's {@link
* InvocationHandler#invoke invoke} method as described in the
* documentation for that method.
*
* <li>An invocation of the {@code hashCode},
* {@code equals}, or {@code toString} methods declared in
* {@code java.lang.Object} on a proxy instance will be encoded and
* dispatched to the invocation handler's {@code invoke} method in
* the same manner as interface method invocations are encoded and
* dispatched, as described above. The declaring class of the
* {@code Method} object passed to {@code invoke} will be
* {@code java.lang.Object}. Other public methods of a proxy
* instance inherited from {@code java.lang.Object} are not
* overridden by a proxy class, so invocations of those methods behave
* like they do for instances of {@code java.lang.Object}.
* </ul>
*
* <h3><a name="membership">Package and Module Membership of Proxy Class</a></h3>
*
* The package and module to which a proxy class belongs are chosen such that
* the accessibility of the proxy class is in line with the accessibility of
* the proxy interfaces. Specifically, the package and the module membership
* of a proxy class defined via the
* {@link Proxy#getProxyClass(ClassLoader, Class[])} or
* {@link Proxy#newProxyInstance(ClassLoader, Class[], InvocationHandler)}
* methods is specified as follows:
*
* <ol>
* <li>If all the proxy interfaces are in <em>exported</em> packages:
* <ol type="a">
* <li>if all the proxy interfaces are <em>public</em>, then the proxy class is
* <em>public</em> in a package exported by the
* {@linkplain ClassLoader#getUnnamedModule() unnamed module} of the specified
* loader. The name of the package is unspecified.</li>
*
* <li>if at least one of all the proxy interfaces is <em>non-public</em>, then
* the proxy class is <em>non-public</em> in the package and module of the
* non-public interfaces. All the non-public interfaces must be in the same
* package and module; otherwise, proxying them is
* <a href="#restrictions">not possible</a>.</li>
* </ol>
* </li>
* <li>If at least one proxy interface is a <em>non-exported</em> package:
* <ol type="a">
* <li>if all the proxy interfaces are <em>public</em>, then the proxy class is
* <em>public</em> in a <em>non-exported</em> package of
* <a href="#dynamicmodule"><em>dynamic module</em>.</a>
* The names of the package and the module are unspecified.</li>
*
* <li>if at least one of all the proxy interfaces is <em>non-public</em>, then
* the proxy class is <em>non-public</em> in the package and module of the
* non-public interfaces. All the non-public interfaces must be in the same
* package and module; otherwise, proxying them is
* <a href="#restrictions">not possible</a>.</li>
* </ol>
* </li>
* </ol>
*
* <p>
* Note that if proxy interfaces with a mix of accessibilities --
* exported public, exported non-public, non-exported public, non-exported non-public --
* are proxied by the same instance, then the proxy class's accessibility is
* governed by the least accessible proxy interface.
* <p>
* Note that it is possible for arbitrary code to obtain access to a proxy class
* in an exported package with {@link AccessibleObject#setAccessible setAccessible},
* whereas a proxy class in a non-exported package is never accessible to
* code outside the module of the proxy class.
*
* <p>
* Throughout this specification, a "non-exported package" refers to a package that
* is not exported to all modules. Specifically, it refers to a package that
* either is not exported at all by its containing module or is exported in a
* qualified fashion by its containing module.
*
* <h3><a name="dynamicmodule">Dynamic Modules</a></h3>
* <p>
* A dynamic module is a named module generated at runtime. A proxy class
* defined in a dynamic module is encapsulated and not accessible to any module.
* Calling {@link Constructor#newInstance(Object...)} on a proxy class in
* a dynamic module will throw {@code IllegalAccessException};
* {@code Proxy.newProxyInstance} method should be used instead.
*
* <p>
* A dynamic module can read the modules of all of the superinterfaces of a proxy class
* and the modules of the types referenced by all public method signatures
* of a proxy class. If a superinterface or a referenced type, say {@code T},
* is in a non-exported package, the {@linkplain java.lang.reflect.Module module}
* of {@code T} is updated to export the package of {@code T} to the dynamic module.
*
* <h3>Methods Duplicated in Multiple Proxy Interfaces</h3>
*
* <p>When two or more proxy interfaces contain a method with
* the same name and parameter signature, the order of the proxy class's
* interfaces becomes significant. When such a <i>duplicate method</i>
* is invoked on a proxy instance, the {@code Method} object passed
* to the invocation handler will not necessarily be the one whose
* declaring class is assignable from the reference type of the interface
* that the proxy's method was invoked through. This limitation exists
* because the corresponding method implementation in the generated proxy
* class cannot determine which interface it was invoked through.
* Therefore, when a duplicate method is invoked on a proxy instance,
* the {@code Method} object for the method in the foremost interface
* that contains the method (either directly or inherited through a
* superinterface) in the proxy class's list of interfaces is passed to
* the invocation handler's {@code invoke} method, regardless of the
* reference type through which the method invocation occurred.
*
* <p>If a proxy interface contains a method with the same name and
* parameter signature as the {@code hashCode}, {@code equals},
* or {@code toString} methods of {@code java.lang.Object},
* when such a method is invoked on a proxy instance, the
* {@code Method} object passed to the invocation handler will have
* {@code java.lang.Object} as its declaring class. In other words,
* the public, non-final methods of {@code java.lang.Object}
* logically precede all of the proxy interfaces for the determination of
* which {@code Method} object to pass to the invocation handler.
*
* <p>Note also that when a duplicate method is dispatched to an
* invocation handler, the {@code invoke} method may only throw
* checked exception types that are assignable to one of the exception
* types in the {@code throws} clause of the method in <i>all</i> of
* the proxy interfaces that it can be invoked through. If the
* {@code invoke} method throws a checked exception that is not
* assignable to any of the exception types declared by the method in one
* of the proxy interfaces that it can be invoked through, then an
* unchecked {@code UndeclaredThrowableException} will be thrown by
* the invocation on the proxy instance. This restriction means that not
* all of the exception types returned by invoking
* {@code getExceptionTypes} on the {@code Method} object
* passed to the {@code invoke} method can necessarily be thrown
* successfully by the {@code invoke} method.
*
* @author Peter Jones
* @see InvocationHandler
* @since 1.3
*/
public class Proxy implements java.io.Serializable {
private static final long serialVersionUID = -2222568056686623797L;
/** parameter types of a proxy class constructor */
private static final Class<?>[] constructorParams =
{ InvocationHandler.class };
/**
* a cache of proxy constructors with
* {@link Constructor#setAccessible(boolean) accessible} flag already set
*/
private static final ClassLoaderValue<Constructor<?>> proxyCache =
new ClassLoaderValue<>();
/**
* the invocation handler for this proxy instance.
* @serial
*/
protected InvocationHandler h;
/**
* Prohibits instantiation.
*/
private Proxy() {
}
/**
* Constructs a new {@code Proxy} instance from a subclass
* (typically, a dynamic proxy class) with the specified value
* for its invocation handler.
*
* @param h the invocation handler for this proxy instance
*
* @throws NullPointerException if the given invocation handler, {@code h},
* is {@code null}.
*/
protected Proxy(InvocationHandler h) {
Objects.requireNonNull(h);
this.h = h;
}
/**
* Returns the {@code java.lang.Class} object for a proxy class
* given a class loader and an array of interfaces. The proxy class
* will be defined by the specified class loader and will implement
* all of the supplied interfaces. If any of the given interfaces
* is non-public, the proxy class will be non-public. If a proxy class
* for the same permutation of interfaces has already been defined by the
* class loader, then the existing proxy class will be returned; otherwise,
* a proxy class for those interfaces will be generated dynamically
* and defined by the class loader.
*
* @param loader the class loader to define the proxy class
* @param interfaces the list of interfaces for the proxy class
* to implement
* @return a proxy class that is defined in the specified class loader
* and that implements the specified interfaces
* @throws IllegalArgumentException if any of the <a href="#restrictions">
* restrictions</a> on the parameters are violated
* @throws SecurityException if a security manager, <em>s</em>, is present
* and any of the following conditions is met:
* <ul>
* <li> the given {@code loader} is {@code null} and
* the caller's class loader is not {@code null} and the
* invocation of {@link SecurityManager#checkPermission
* s.checkPermission} with
* {@code RuntimePermission("getClassLoader")} permission
* denies access.</li>
* <li> for each proxy interface, {@code intf},
* the caller's class loader is not the same as or an
* ancestor of the class loader for {@code intf} and
* invocation of {@link SecurityManager#checkPackageAccess
* s.checkPackageAccess()} denies access to {@code intf}.</li>
* </ul>
* @throws NullPointerException if the {@code interfaces} array
* argument or any of its elements are {@code null}
*
* @deprecated Proxy classes generated in a named module are encapsulated and not
* accessible to code outside its module.
* {@link Constructor#newInstance(Object...) Constructor.newInstance} will throw
* {@code IllegalAccessException} when it is called on an inaccessible proxy class.
* Use {@link #newProxyInstance(ClassLoader, Class[], InvocationHandler)}
* to create a proxy instance instead.
*
* @see <a href="#membership">Package and Module Membership of Proxy Class</a>
*/
@Deprecated
@CallerSensitive
public static Class<?> getProxyClass(ClassLoader loader,
Class<?>... interfaces)
throws IllegalArgumentException
{
Class<?> caller = System.getSecurityManager() == null
? null
: Reflection.getCallerClass();
return getProxyConstructor(caller, loader, interfaces)
.getDeclaringClass();
}
/**
* Returns the {@code Constructor} object of a proxy class that takes a
* single argument of type {@link InvocationHandler}, given a class loader
* and an array of interfaces. The returned constructor will have the
* {@link Constructor#setAccessible(boolean) accessible} flag already set.
*
* @param caller passed from a public-facing @CallerSensitive method if
* SecurityManager is set or {@code null} if there's no
* SecurityManager
* @param loader the class loader to define the proxy class
* @param interfaces the list of interfaces for the proxy class
* to implement
* @return a Constructor of the proxy class taking single
* {@code InvocationHandler} parameter
*/
private static Constructor<?> getProxyConstructor(Class<?> caller,
ClassLoader loader,
Class<?>... interfaces)
{
// optimization for single interface
if (interfaces.length == 1) {
Class<?> intf = interfaces[0];
if (caller != null) {
checkProxyAccess(caller, loader, intf);
}
return proxyCache.sub(intf).computeIfAbsent(
loader,
(ld, clv) -> new ProxyBuilder(ld, clv.key()).build()
);
} else {
// interfaces cloned
final Class<?>[] intfsArray = interfaces.clone();
if (caller != null) {
checkProxyAccess(caller, loader, intfsArray);
}
final List<Class<?>> intfs = Arrays.asList(intfsArray);
return proxyCache.sub(intfs).computeIfAbsent(
loader,
(ld, clv) -> new ProxyBuilder(ld, clv.key()).build()
);
}
}
/*
* Check permissions required to create a Proxy class.
*
* To define a proxy class, it performs the access checks as in
* Class.forName (VM will invoke ClassLoader.checkPackageAccess):
* 1. "getClassLoader" permission check if loader == null
* 2. checkPackageAccess on the interfaces it implements
*
* To get a constructor and new instance of a proxy class, it performs
* the package access check on the interfaces it implements
* as in Class.getConstructor.
*
* If an interface is non-public, the proxy class must be defined by
* the defining loader of the interface. If the caller's class loader
* is not the same as the defining loader of the interface, the VM
* will throw IllegalAccessError when the generated proxy class is
* being defined.
*/
private static void checkProxyAccess(Class<?> caller,
ClassLoader loader,
Class<?> ... interfaces)
{
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
ClassLoader ccl = caller.getClassLoader();
if (VM.isSystemDomainLoader(loader) && !VM.isSystemDomainLoader(ccl)) {
sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
}
ReflectUtil.checkProxyPackageAccess(ccl, interfaces);
}
}
/**
* Builder for a proxy class.
*
* If the module is not specified in this ProxyBuilder constructor,
* it will map from the given loader and interfaces to the module
* in which the proxy class will be defined.
*/
private static final class ProxyBuilder {
private static final Unsafe UNSAFE = Unsafe.getUnsafe();
// prefix for all proxy class names
private static final String proxyClassNamePrefix = "$Proxy";
// next number to use for generation of unique proxy class names
private static final AtomicLong nextUniqueNumber = new AtomicLong();
// a reverse cache of defined proxy classes
private static final ClassLoaderValue<Boolean> reverseProxyCache =
new ClassLoaderValue<>();
private static Class<?> defineProxyClass(Module m, List<Class<?>> interfaces) {
String proxyPkg = null; // package to define proxy class in
int accessFlags = Modifier.PUBLIC | Modifier.FINAL;
/*
* Record the package of a non-public proxy interface so that the
* proxy class will be defined in the same package. Verify that
* all non-public proxy interfaces are in the same package.
*/
for (Class<?> intf : interfaces) {
int flags = intf.getModifiers();
if (!Modifier.isPublic(flags)) {
accessFlags = Modifier.FINAL; // non-public, final
String pkg = intf.getPackageName();
if (proxyPkg == null) {
proxyPkg = pkg;
} else if (!pkg.equals(proxyPkg)) {
throw new IllegalArgumentException(
"non-public interfaces from different packages");
}
}
}
if (proxyPkg == null) {
// all proxy interfaces are public
proxyPkg = m.isNamed() ? PROXY_PACKAGE_PREFIX + "." + m.getName()
: PROXY_PACKAGE_PREFIX;
} else if (proxyPkg.isEmpty() && m.isNamed()) {
throw new IllegalArgumentException(
"Unnamed package cannot be added to " + m);
}
// add the package to the runtime module if not exists
if (m.isNamed()) {
m.addPackage(proxyPkg);
}
/*
* Choose a name for the proxy class to generate.
*/
long num = nextUniqueNumber.getAndIncrement();
String proxyName = proxyPkg.isEmpty() ? proxyClassNamePrefix + num
: proxyPkg + "." + proxyClassNamePrefix + num;
ClassLoader loader = getLoader(m);
trace(proxyName, m, loader, interfaces);
/*
* Generate the specified proxy class.
*/
byte[] proxyClassFile = ProxyGenerator.generateProxyClass(
proxyName, interfaces.toArray(EMPTY_CLASS_ARRAY), accessFlags);
try {
Class<?> pc = UNSAFE.defineClass(proxyName, proxyClassFile,
0, proxyClassFile.length,
loader, null);
reverseProxyCache.sub(pc).putIfAbsent(loader, Boolean.TRUE);
return pc;
} catch (ClassFormatError e) {
/*
* A ClassFormatError here means that (barring bugs in the
* proxy class generation code) there was some other
* invalid aspect of the arguments supplied to the proxy
* class creation (such as virtual machine limitations
* exceeded).
*/
throw new IllegalArgumentException(e.toString());
}
}
/**
* Test if given class is a class defined by
* {@link #defineProxyClass(Module, List)}
*/
static boolean isProxyClass(Class<?> c) {
return Objects.equals(reverseProxyCache.sub(c).get(c.getClassLoader()),
Boolean.TRUE);
}
private static boolean isExportedType(Class<?> c) {
String pn = c.getPackageName();
return Modifier.isPublic(c.getModifiers()) && c.getModule().isExported(pn);
}
private static boolean isPackagePrivateType(Class<?> c) {
return !Modifier.isPublic(c.getModifiers());
}
private static String toDetails(Class<?> c) {
String access = "unknown";
if (isExportedType(c)) {
access = "exported";
} else if (isPackagePrivateType(c)) {
access = "package-private";
} else {
access = "module-private";
}
ClassLoader ld = c.getClassLoader();
return String.format(" %s/%s %s loader %s",
c.getModule().getName(), c.getName(), access, ld);
}
static void trace(String cn, Module module, ClassLoader loader, List<Class<?>> interfaces) {
if (isDebug()) {
System.out.format("PROXY: %s/%s defined by %s%n", module.getName(), cn, loader);
}
if (isDebug("debug")) {
interfaces.stream()
.forEach(c -> System.out.println(toDetails(c)));
}
}
private static final String DEBUG =
GetPropertyAction.privilegedGetProperty("jdk.proxy.debug", "");
private static boolean isDebug() {
return !DEBUG.isEmpty();
}
private static boolean isDebug(String flag) {
return DEBUG.equals(flag);
}
// ProxyBuilder instance members start here....
private final ClassLoader loader;
private final List<Class<?>> interfaces;
private final Module module;
ProxyBuilder(ClassLoader loader, List<Class<?>> interfaces) {
if (!VM.isModuleSystemInited()) {
throw new InternalError("Proxy is not supported until module system is fully initialized");
}
if (interfaces.size() > 65535) {
throw new IllegalArgumentException("interface limit exceeded: " + interfaces.size());
}
Set<Class<?>> refTypes = referencedTypes(loader, interfaces);
// IAE if violates any restrictions specified in newProxyInstance
validateProxyInterfaces(loader, interfaces, refTypes);
this.loader = loader;
this.interfaces = interfaces;
this.module = mapToModule(loader, interfaces, refTypes);
assert getLoader(module) == loader;
}
ProxyBuilder(ClassLoader loader, Class<?> intf) {
this(loader, Collections.singletonList(intf));
}
/**
* Generate a proxy class and return its proxy Constructor with
* accessible flag already set. If the target module does not have access
* to any interface types, IllegalAccessError will be thrown by the VM
* at defineClass time.
*
* Must call the checkProxyAccess method to perform permission checks
* before calling this.
*/
Constructor<?> build() {
Class<?> proxyClass = defineProxyClass(module, interfaces);
final Constructor<?> cons;
try {
cons = proxyClass.getConstructor(constructorParams);
} catch (NoSuchMethodException e) {
throw new InternalError(e.toString(), e);
}
AccessController.doPrivileged(new PrivilegedAction<Void>() {
public Void run() {
cons.setAccessible(true);
return null;
}
});
return cons;
}
/**
* Validate the given proxy interfaces and the given referenced types
* are visible to the defining loader.
*
* @throws IllegalArgumentException if it violates the restrictions specified
* in {@link Proxy#newProxyInstance}
*/
private static void validateProxyInterfaces(ClassLoader loader,
List<Class<?>> interfaces,
Set<Class<?>> refTypes)
{
Map<Class<?>, Boolean> interfaceSet = new IdentityHashMap<>(interfaces.size());
for (Class<?> intf : interfaces) {
/*
* Verify that the class loader resolves the name of this
* interface to the same Class object.
*/
ensureVisible(loader, intf);
/*
* Verify that the Class object actually represents an
* interface.
*/
if (!intf.isInterface()) {
throw new IllegalArgumentException(intf.getName() + " is not an interface");
}
/*
* Verify that this interface is not a duplicate.
*/
if (interfaceSet.put(intf, Boolean.TRUE) != null) {
throw new IllegalArgumentException("repeated interface: " + intf.getName());
}
}
for (Class<?> type : refTypes) {
ensureVisible(loader, type);
}
}
/*
* Returns all types referenced by all public non-static method signatures of
* the proxy interfaces
*/
private static Set<Class<?>> referencedTypes(ClassLoader loader,
List<Class<?>> interfaces) {
return interfaces.stream()
.flatMap(intf -> Stream.of(intf.getMethods())
.filter(m -> !Modifier.isStatic(m.getModifiers()))
.flatMap(ProxyBuilder::methodRefTypes)
.map(ProxyBuilder::getElementType)
.filter(t -> !t.isPrimitive()))
.collect(Collectors.toSet());
}
/*
* Extracts all types referenced on a method signature including
* its return type, parameter types, and exception types.
*/
private static Stream<Class<?>> methodRefTypes(Method m) {
return Stream.of(new Class<?>[] { m.getReturnType() },
m.getParameterTypes(),
m.getExceptionTypes())
.flatMap(Stream::of);
}
/**
* Returns the module that the generated proxy class belongs to.
*
* If all proxy interfaces are public and in exported packages,
* then the proxy class is in unnamed module.
*
* If any of proxy interface is package-private, then the proxy class
* is in the same module of the package-private interface.
*
* If all proxy interfaces are public and at least one in a non-exported
* package, then the proxy class is in a dynamic module in a non-exported
* package. Reads edge and qualified exports are added for
* dynamic module to access.
*/
private static Module mapToModule(ClassLoader loader,
List<Class<?>> interfaces,
Set<Class<?>> refTypes) {
Map<Class<?>, Module> modulePrivateTypes = new HashMap<>();
Map<Class<?>, Module> packagePrivateTypes = new HashMap<>();
for (Class<?> intf : interfaces) {
Module m = intf.getModule();
if (Modifier.isPublic(intf.getModifiers())) {
// module-private types
if (!m.isExported(intf.getPackageName())) {
modulePrivateTypes.put(intf, m);
}
} else {
packagePrivateTypes.put(intf, m);
}
}
// all proxy interfaces are public and exported, the proxy class is in unnamed module
// Such proxy class is accessible to any unnamed module and named module that
// can read unnamed module
if (packagePrivateTypes.isEmpty() && modulePrivateTypes.isEmpty()) {
return loader != null ? loader.getUnnamedModule() : BootLoader.getUnnamedModule();
}
if (packagePrivateTypes.size() > 0) {
// all package-private types must be in the same runtime package
// i.e. same package name and same module (named or unnamed)
//
// Configuration will fail if M1 and in M2 defined by the same loader
// and both have the same package p (so no need to check class loader)
if (packagePrivateTypes.size() > 1 &&
(packagePrivateTypes.keySet().stream() // more than one package
.map(Class::getPackageName).distinct().count() > 1 ||
packagePrivateTypes.values().stream() // or more than one module
.distinct().count() > 1)) {
throw new IllegalArgumentException(
"non-public interfaces from different packages");
}
// all package-private types are in the same module (named or unnamed)
Module target = null;
for (Module m : packagePrivateTypes.values()) {
if (getLoader(m) != loader) {
// the specified loader is not the same class loader of the non-public interface
throw new IllegalArgumentException(
"non-public interface is not defined by the given loader");
}
target = m;
}
// validate if the target module can access all other interfaces
for (Class<?> intf : interfaces) {
Module m = intf.getModule();
if (m == target) continue;
if (!target.canRead(m) || !m.isExported(intf.getPackageName(), target)) {
throw new IllegalArgumentException(target + " can't access " + intf.getName());
}
}
// return the module of the package-private interface
return target;
}
// all proxy interfaces are public and at least one in a non-exported package
// map to dynamic proxy module and add reads edge and qualified exports, if necessary
Module target = getDynamicModule(loader);
// set up proxy class access to proxy interfaces and types
// referenced in the method signature
Set<Class<?>> types = new HashSet<>(interfaces);
types.addAll(refTypes);
for (Class<?> c : types) {
ensureAccess(target, c);
}
return target;
}
/*
* Ensure the given module can access the given class.
*/
private static void ensureAccess(Module target, Class<?> c) {
Module m = c.getModule();
// add read edge and qualified export for the target module to access
if (!target.canRead(m)) {
Modules.addReads(target, m);
}
String pn = c.getPackageName();
if (!m.isExported(pn, target)) {
Modules.addExports(m, pn, target);
}
}
/*
* Ensure the given class is visible to the class loader.
*/
private static void ensureVisible(ClassLoader ld, Class<?> c) {
Class<?> type = null;
try {
type = Class.forName(c.getName(), false, ld);
} catch (ClassNotFoundException e) {
}
if (type != c) {
throw new IllegalArgumentException(c.getName() +
" referenced from a method is not visible from class loader");
}
}
private static Class<?> getElementType(Class<?> type) {
Class<?> e = type;
while (e.isArray()) {
e = e.getComponentType();
}
return e;
}
private static final ClassLoaderValue<Module> dynProxyModules =
new ClassLoaderValue<>();
private static final AtomicInteger counter = new AtomicInteger();
/*
* Define a dynamic module for the generated proxy classes in a non-exported package
* named com.sun.proxy.$MODULE.
*
* Each class loader will have one dynamic module.
*/
private static Module getDynamicModule(ClassLoader loader) {
return dynProxyModules.computeIfAbsent(loader, (ld, clv) -> {
// create a dynamic module and setup module access
String mn = "jdk.proxy" + counter.incrementAndGet();
String pn = PROXY_PACKAGE_PREFIX + "." + mn;
Module m = Modules.defineModule(ld, mn, Collections.singleton(pn));
Modules.addReads(m, Proxy.class.getModule());
// java.base to create proxy instance
Modules.addExports(m, pn, Object.class.getModule());
return m;
});
}
}
/**
* Returns a proxy instance for the specified interfaces
* that dispatches method invocations to the specified invocation
* handler.
* <p>
* <a name="restrictions">{@code IllegalArgumentException} will be thrown
* if any of the following restrictions is violated:</a>
* <ul>
* <li>All of {@code Class} objects in the given {@code interfaces} array
* must represent interfaces, not classes or primitive types.
*
* <li>No two elements in the {@code interfaces} array may
* refer to identical {@code Class} objects.
*
* <li>All of the interface types must be visible by name through the
* specified class loader. In other words, for class loader
* {@code cl} and every interface {@code i}, the following
* expression must be true:<p>
* {@code Class.forName(i.getName(), false, cl) == i}
*
* <li>All of the types referenced by all
* public method signatures of the specified interfaces
* and those inherited by their superinterfaces
* must be visible by name through the specified class loader.
*
* <li>All non-public interfaces must be in the same package
* and module, defined by the specified class loader and
* the module of the non-public interfaces can access all of
* the interface types; otherwise, it would not be possible for
* the proxy class to implement all of the interfaces,
* regardless of what package it is defined in.
*
* <li>For any set of member methods of the specified interfaces
* that have the same signature:
* <ul>
* <li>If the return type of any of the methods is a primitive
* type or void, then all of the methods must have that same
* return type.
* <li>Otherwise, one of the methods must have a return type that
* is assignable to all of the return types of the rest of the
* methods.
* </ul>
*
* <li>The resulting proxy class must not exceed any limits imposed
* on classes by the virtual machine. For example, the VM may limit
* the number of interfaces that a class may implement to 65535; in
* that case, the size of the {@code interfaces} array must not
* exceed 65535.
* </ul>
*
* <p>Note that the order of the specified proxy interfaces is
* significant: two requests for a proxy class with the same combination
* of interfaces but in a different order will result in two distinct
* proxy classes.
*
* @param loader the class loader to define the proxy class
* @param interfaces the list of interfaces for the proxy class
* to implement
* @param h the invocation handler to dispatch method invocations to
* @return a proxy instance with the specified invocation handler of a
* proxy class that is defined by the specified class loader
* and that implements the specified interfaces
* @throws IllegalArgumentException if any of the <a href="#restrictions">
* restrictions</a> on the parameters are violated
* @throws SecurityException if a security manager, <em>s</em>, is present
* and any of the following conditions is met:
* <ul>
* <li> the given {@code loader} is {@code null} and
* the caller's class loader is not {@code null} and the
* invocation of {@link SecurityManager#checkPermission
* s.checkPermission} with
* {@code RuntimePermission("getClassLoader")} permission
* denies access;</li>
* <li> for each proxy interface, {@code intf},
* the caller's class loader is not the same as or an
* ancestor of the class loader for {@code intf} and
* invocation of {@link SecurityManager#checkPackageAccess
* s.checkPackageAccess()} denies access to {@code intf};</li>
* <li> any of the given proxy interfaces is non-public and the
* caller class is not in the same {@linkplain Package runtime package}
* as the non-public interface and the invocation of
* {@link SecurityManager#checkPermission s.checkPermission} with
* {@code ReflectPermission("newProxyInPackage.{package name}")}
* permission denies access.</li>
* </ul>
* @throws NullPointerException if the {@code interfaces} array
* argument or any of its elements are {@code null}, or
* if the invocation handler, {@code h}, is
* {@code null}
*
* @see <a href="#membership">Package and Module Membership of Proxy Class</a>
*/
@CallerSensitive
public static Object newProxyInstance(ClassLoader loader,
Class<?>[] interfaces,
InvocationHandler h) {
Objects.requireNonNull(h);
final Class<?> caller = System.getSecurityManager() == null
? null
: Reflection.getCallerClass();
/*
* Look up or generate the designated proxy class and its constructor.
*/
Constructor<?> cons = getProxyConstructor(caller, loader, interfaces);
return newProxyInstance(caller, cons, h);
}
private static Object newProxyInstance(Class<?> caller, // null if no SecurityManager
Constructor<?> cons,
InvocationHandler h) {
/*
* Invoke its constructor with the designated invocation handler.
*/
try {
if (caller != null) {
checkNewProxyPermission(caller, cons.getDeclaringClass());
}
return cons.newInstance(new Object[]{h});
} catch (IllegalAccessException | InstantiationException e) {
throw new InternalError(e.toString(), e);
} catch (InvocationTargetException e) {
Throwable t = e.getCause();
if (t instanceof RuntimeException) {
throw (RuntimeException) t;
} else {
throw new InternalError(t.toString(), t);
}
}
}
private static void checkNewProxyPermission(Class<?> caller, Class<?> proxyClass) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
if (ReflectUtil.isNonPublicProxyClass(proxyClass)) {
ClassLoader ccl = caller.getClassLoader();
ClassLoader pcl = proxyClass.getClassLoader();
// do permission check if the caller is in a different runtime package
// of the proxy class
int n = proxyClass.getName().lastIndexOf('.');
String pkg = (n == -1) ? "" : proxyClass.getName().substring(0, n);
n = caller.getName().lastIndexOf('.');
String callerPkg = (n == -1) ? "" : caller.getName().substring(0, n);
if (pcl != ccl || !pkg.equals(callerPkg)) {
sm.checkPermission(new ReflectPermission("newProxyInPackage." + pkg));
}
}
}
}
/**
* Returns the class loader for the given module.
*/
private static ClassLoader getLoader(Module m) {
PrivilegedAction<ClassLoader> pa = m::getClassLoader;
return AccessController.doPrivileged(pa);
}
/**
* Returns true if the given class is a proxy class.
*
* @implNote The reliability of this method is important for the ability
* to use it to make security decisions, so its implementation should
* not just test if the class in question extends {@code Proxy}.
*
* @param cl the class to test
* @return {@code true} if the class is a proxy class and
* {@code false} otherwise
* @throws NullPointerException if {@code cl} is {@code null}
*/
public static boolean isProxyClass(Class<?> cl) {
return Proxy.class.isAssignableFrom(cl) && ProxyBuilder.isProxyClass(cl);
}
/**
* Returns the invocation handler for the specified proxy instance.
*
* @param proxy the proxy instance to return the invocation handler for
* @return the invocation handler for the proxy instance
* @throws IllegalArgumentException if the argument is not a
* proxy instance
* @throws SecurityException if a security manager, <em>s</em>, is present
* and the caller's class loader is not the same as or an
* ancestor of the class loader for the invocation handler
* and invocation of {@link SecurityManager#checkPackageAccess
* s.checkPackageAccess()} denies access to the invocation
* handler's class.
*/
@CallerSensitive
public static InvocationHandler getInvocationHandler(Object proxy)
throws IllegalArgumentException
{
/*
* Verify that the object is actually a proxy instance.
*/
if (!isProxyClass(proxy.getClass())) {
throw new IllegalArgumentException("not a proxy instance");
}
final Proxy p = (Proxy) proxy;
final InvocationHandler ih = p.h;
if (System.getSecurityManager() != null) {
Class<?> ihClass = ih.getClass();
Class<?> caller = Reflection.getCallerClass();
if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(),
ihClass.getClassLoader()))
{
ReflectUtil.checkPackageAccess(ihClass);
}
}
return ih;
}
private static final Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[0];
private static final String PROXY_PACKAGE_PREFIX = ReflectUtil.PROXY_PACKAGE;
}