1 /*
2 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.lang.reflect;
27
28 import java.lang.ref.WeakReference;
29 import java.security.AccessController;
30 import java.security.PrivilegedAction;
31 import java.util.Arrays;
32 import java.util.Collections;
33 import java.util.Deque;
34 import java.util.HashMap;
35 import java.util.HashSet;
36 import java.util.IdentityHashMap;
37 import java.util.LinkedList;
38 import java.util.List;
39 import java.util.Map;
40 import java.util.Objects;
41 import java.util.Set;
42 import java.util.WeakHashMap;
43 import java.util.concurrent.atomic.AtomicInteger;
44 import java.util.concurrent.atomic.AtomicLong;
45 import java.util.function.BiFunction;
46 import java.util.stream.Collectors;
47 import java.util.stream.Stream;
48
49 import jdk.internal.loader.BootLoader;
50 import jdk.internal.module.Modules;
51 import jdk.internal.misc.VM;
52 import sun.misc.Unsafe;
53 import sun.reflect.CallerSensitive;
54 import sun.reflect.Reflection;
55 import sun.reflect.misc.ReflectUtil;
56 import sun.security.util.SecurityConstants;
57
58 /**
59 *
60 * {@code Proxy} provides static methods for creating objects that act like instances
61 * of interfaces but allow for customized method invocation.
62 * To create a proxy instance for some interface {@code Foo}:
63 * <pre>{@code
64 * InvocationHandler handler = new MyInvocationHandler(...);
65 * Foo f = (Foo) Proxy.newProxyInstance(Foo.class.getClassLoader(),
66 * new Class<?>[] { Foo.class },
67 * handler);
68 * }</pre>
69 *
70 * <p>
71 * A <em>proxy class</em> is a class created at runtime that implements a specified
72 * list of interfaces, known as <em>proxy interfaces</em>. A <em>proxy instance</em>
73 * is an instance of a proxy class.
74 *
75 * Each proxy instance has an associated <i>invocation handler</i>
76 * object, which implements the interface {@link InvocationHandler}.
77 * A method invocation on a proxy instance through one of its proxy
78 * interfaces will be dispatched to the {@link InvocationHandler#invoke
79 * invoke} method of the instance's invocation handler, passing the proxy
80 * instance, a {@code java.lang.reflect.Method} object identifying
81 * the method that was invoked, and an array of type {@code Object}
82 * containing the arguments. The invocation handler processes the
83 * encoded method invocation as appropriate and the result that it
84 * returns will be returned as the result of the method invocation on
85 * the proxy instance.
86 *
87 * <p>A proxy class has the following properties:
88 *
89 * <ul>
90 * <li>The unqualified name of a proxy class is unspecified. The space
91 * of class names that begin with the string {@code "$Proxy"}
92 * should be, however, reserved for proxy classes.
93 *
94 * <li>The package and module in which a proxy class is defined is specified
95 * <a href="#membership">below</a>.
96 *
97 * <li>A proxy class is <em>final and non-abstract</em>.
98 *
99 * <li>A proxy class extends {@code java.lang.reflect.Proxy}.
100 *
101 * <li>A proxy class implements exactly the interfaces specified at its
102 * creation, in the same order. Invoking {@link Class#getInterfaces getInterfaces}
103 * on its {@code Class} object will return an array containing the same
104 * list of interfaces (in the order specified at its creation), invoking
105 * {@link Class#getMethods getMethods} on its {@code Class} object will return
106 * an array of {@code Method} objects that include all of the
107 * methods in those interfaces, and invoking {@code getMethod} will
108 * find methods in the proxy interfaces as would be expected.
109 *
110 * <li>The {@link java.security.ProtectionDomain} of a proxy class
111 * is the same as that of system classes loaded by the bootstrap class
112 * loader, such as {@code java.lang.Object}, because the code for a
113 * proxy class is generated by trusted system code. This protection
114 * domain will typically be granted {@code java.security.AllPermission}.
115 *
116 * <li>The {@link Proxy#isProxyClass Proxy.isProxyClass} method can be used
117 * to determine if a given class is a proxy class.
118 * </ul>
119 *
120 * <p>A proxy instance has the following properties:
121 *
122 * <ul>
123 * <li>Given a proxy instance {@code proxy} and one of the
124 * interfaces, {@code Foo}, implemented by its proxy class, the
125 * following expression will return true:
126 * <pre>
127 * {@code proxy instanceof Foo}
128 * </pre>
129 * and the following cast operation will succeed (rather than throwing
130 * a {@code ClassCastException}):
131 * <pre>
132 * {@code (Foo) proxy}
133 * </pre>
134 *
135 * <li>Each proxy instance has an associated invocation handler, the one
136 * that was passed to its constructor. The static
137 * {@link Proxy#getInvocationHandler Proxy.getInvocationHandler} method
138 * will return the invocation handler associated with the proxy instance
139 * passed as its argument.
140 *
141 * <li>An interface method invocation on a proxy instance will be
142 * encoded and dispatched to the invocation handler's {@link
143 * InvocationHandler#invoke invoke} method as described in the
144 * documentation for that method.
145 *
146 * <li>An invocation of the {@code hashCode},
147 * {@code equals}, or {@code toString} methods declared in
148 * {@code java.lang.Object} on a proxy instance will be encoded and
149 * dispatched to the invocation handler's {@code invoke} method in
150 * the same manner as interface method invocations are encoded and
151 * dispatched, as described above. The declaring class of the
152 * {@code Method} object passed to {@code invoke} will be
153 * {@code java.lang.Object}. Other public methods of a proxy
154 * instance inherited from {@code java.lang.Object} are not
155 * overridden by a proxy class, so invocations of those methods behave
156 * like they do for instances of {@code java.lang.Object}.
157 * </ul>
158 *
159 * <h3><a name="membership">Package and Module Membership of Proxy Class</a></h3>
160 *
161 * The package and module to which a proxy class belongs are chosen such that
162 * the accessibility of the proxy class is in line with the accessibility of
163 * the proxy interfaces. Specifically, the package and the module membership
164 * of a proxy class defined via the
165 * {@link Proxy#getProxyClass(ClassLoader, Class[])} or
166 * {@link Proxy#newProxyInstance(ClassLoader, Class[], InvocationHandler)}
167 * methods is specified as follows:
168 *
169 * <ol>
170 * <li>If all the proxy interfaces are in <em>exported</em> packages:
171 * <ol type="a">
172 * <li>if all the proxy interfaces are <em>public</em>, then the proxy class is
173 * <em>public</em> in a package exported by the
174 * {@linkplain ClassLoader#getUnnamedModule() unnamed module} of the specified
175 * loader. The name of the package is unspecified.</li>
176 *
177 * <li>if at least one of all the proxy interfaces is <em>non-public</em>, then
178 * the proxy class is <em>non-public</em> in the package and module of the
179 * non-public interfaces. All the non-public interfaces must be in the same
180 * package and module; otherwise, proxying them is
181 * <a href="#restrictions">not possible</a>.</li>
182 * </ol>
183 * </li>
184 * <li>If at least one proxy interface is a <em>non-exported</em> package:
185 * <ol type="a">
186 * <li>if all the proxy interfaces are <em>public</em>, then the proxy class is
187 * <em>public</em> in a <em>non-exported</em> package of
188 * <a href="#dynamicmodule"><em>dynamic module</em>.</a>
189 * The names of the package and the module are unspecified.</li>
190 *
191 * <li>if at least one of all the proxy interfaces is <em>non-public</em>, then
192 * the proxy class is <em>non-public</em> in the package and module of the
193 * non-public interfaces. All the non-public interfaces must be in the same
194 * package and module; otherwise, proxying them is
195 * <a href="#restrictions">not possible</a>.</li>
196 * </ol>
197 * </li>
198 * </ol>
199 *
200 * <p>
201 * Note that if proxy interfaces with a mix of accessibilities --
202 * exported public, exported non-public, non-exported public, non-exported non-public --
203 * are proxied by the same instance, then the proxy class's accessibility is
204 * governed by the least accessible proxy interface.
205 * <p>
206 * Note that it is possible for arbitrary code to obtain access to a proxy class
207 * in an exported package with {@link AccessibleObject#setAccessible setAccessible},
208 * whereas a proxy class in a non-exported package is never accessible to
209 * code outside the module of the proxy class.
210 *
211 * <p>
212 * Throughout this specification, a "non-exported package" refers to a package that
213 * is not exported to all modules. Specifically, it refers to a package that
214 * either is not exported at all by its containing module or is exported in a
215 * qualified fashion by its containing module.
216 *
217 * <h3><a name="dynamicmodule">Dynamic Modules</a></h3>
218 * <p>
219 * A dynamic module is a named module generated at runtime. A proxy class
220 * defined in a dynamic module is encapsulated and not accessible to any module.
221 * Calling {@link Constructor#newInstance(Object...)} on a proxy class in
222 * a dynamic module will throw {@code IllegalAccessException};
223 * {@code Proxy.newProxyInstance} method should be used instead.
224 *
225 * <p>
226 * A dynamic module can read the modules of all of the superinterfaces of a proxy class
227 * and the modules of the types referenced by all public method signatures
228 * of a proxy class. If a superinterface or a referenced type, say {@code T},
229 * is in a non-exported package, the {@linkplain java.lang.reflect.Module module}
230 * of {@code T} is updated to export the package of {@code T} to the dynamic module.
231 *
232 * <h3>Methods Duplicated in Multiple Proxy Interfaces</h3>
233 *
234 * <p>When two or more proxy interfaces contain a method with
235 * the same name and parameter signature, the order of the proxy class's
236 * interfaces becomes significant. When such a <i>duplicate method</i>
237 * is invoked on a proxy instance, the {@code Method} object passed
238 * to the invocation handler will not necessarily be the one whose
239 * declaring class is assignable from the reference type of the interface
240 * that the proxy's method was invoked through. This limitation exists
241 * because the corresponding method implementation in the generated proxy
242 * class cannot determine which interface it was invoked through.
243 * Therefore, when a duplicate method is invoked on a proxy instance,
244 * the {@code Method} object for the method in the foremost interface
245 * that contains the method (either directly or inherited through a
246 * superinterface) in the proxy class's list of interfaces is passed to
247 * the invocation handler's {@code invoke} method, regardless of the
248 * reference type through which the method invocation occurred.
249 *
250 * <p>If a proxy interface contains a method with the same name and
251 * parameter signature as the {@code hashCode}, {@code equals},
252 * or {@code toString} methods of {@code java.lang.Object},
253 * when such a method is invoked on a proxy instance, the
254 * {@code Method} object passed to the invocation handler will have
255 * {@code java.lang.Object} as its declaring class. In other words,
256 * the public, non-final methods of {@code java.lang.Object}
257 * logically precede all of the proxy interfaces for the determination of
258 * which {@code Method} object to pass to the invocation handler.
259 *
260 * <p>Note also that when a duplicate method is dispatched to an
261 * invocation handler, the {@code invoke} method may only throw
262 * checked exception types that are assignable to one of the exception
263 * types in the {@code throws} clause of the method in <i>all</i> of
264 * the proxy interfaces that it can be invoked through. If the
265 * {@code invoke} method throws a checked exception that is not
266 * assignable to any of the exception types declared by the method in one
267 * of the proxy interfaces that it can be invoked through, then an
268 * unchecked {@code UndeclaredThrowableException} will be thrown by
269 * the invocation on the proxy instance. This restriction means that not
270 * all of the exception types returned by invoking
271 * {@code getExceptionTypes} on the {@code Method} object
272 * passed to the {@code invoke} method can necessarily be thrown
273 * successfully by the {@code invoke} method.
274 *
275 * @author Peter Jones
276 * @see InvocationHandler
277 * @since 1.3
278 */
279 public class Proxy implements java.io.Serializable {
280 private static final long serialVersionUID = -2222568056686623797L;
281
282 /** parameter types of a proxy class constructor */
283 private static final Class<?>[] constructorParams =
284 { InvocationHandler.class };
285
286 /**
287 * the invocation handler for this proxy instance.
288 * @serial
289 */
290 protected InvocationHandler h;
291
292 /**
293 * Prohibits instantiation.
294 */
295 private Proxy() {
296 }
297
298 /**
299 * Constructs a new {@code Proxy} instance from a subclass
300 * (typically, a dynamic proxy class) with the specified value
301 * for its invocation handler.
302 *
303 * @param h the invocation handler for this proxy instance
304 *
305 * @throws NullPointerException if the given invocation handler, {@code h},
306 * is {@code null}.
307 */
308 protected Proxy(InvocationHandler h) {
309 Objects.requireNonNull(h);
310 this.h = h;
311 }
312
313 /**
314 * Returns the {@code java.lang.Class} object for a proxy class
315 * given a class loader and an array of interfaces. The proxy class
316 * will be defined by the specified class loader and will implement
317 * all of the supplied interfaces. If any of the given interfaces
318 * is non-public, the proxy class will be non-public. If a proxy class
319 * for the same permutation of interfaces has already been defined by the
320 * class loader, then the existing proxy class will be returned; otherwise,
321 * a proxy class for those interfaces will be generated dynamically
322 * and defined by the class loader.
323 *
324 * @param loader the class loader to define the proxy class
325 * @param interfaces the list of interfaces for the proxy class
326 * to implement
327 * @return a proxy class that is defined in the specified class loader
328 * and that implements the specified interfaces
329 * @throws IllegalArgumentException if any of the <a href="#restrictions">
330 * restrictions</a> on the parameters are violated
331 * @throws SecurityException if a security manager, <em>s</em>, is present
332 * and any of the following conditions is met:
333 * <ul>
334 * <li> the given {@code loader} is {@code null} and
335 * the caller's class loader is not {@code null} and the
336 * invocation of {@link SecurityManager#checkPermission
337 * s.checkPermission} with
338 * {@code RuntimePermission("getClassLoader")} permission
339 * denies access.</li>
340 * <li> for each proxy interface, {@code intf},
341 * the caller's class loader is not the same as or an
342 * ancestor of the class loader for {@code intf} and
343 * invocation of {@link SecurityManager#checkPackageAccess
344 * s.checkPackageAccess()} denies access to {@code intf}.</li>
345 * </ul>
346 * @throws NullPointerException if the {@code interfaces} array
347 * argument or any of its elements are {@code null}
348 *
349 * @deprecated Proxy classes generated in a named module are encapsulated and not
350 * accessible to code outside its module.
351 * {@link Constructor#newInstance(Object...) Constructor.newInstance} will throw
352 * {@code IllegalAccessException} when it is called on an inaccessible proxy class.
353 * Use {@link #newProxyInstance(ClassLoader, Class[], InvocationHandler)}
354 * to create a proxy instance instead.
355 *
356 * @see <a href="#membership">Package and Module Membership of Proxy Class</a>
357 */
358 @Deprecated
359 @CallerSensitive
360 public static Class<?> getProxyClass(ClassLoader loader,
361 Class<?>... interfaces)
362 throws IllegalArgumentException
363 {
364 final List<Class<?>> intfs = Arrays.asList(interfaces.clone());
365 final SecurityManager sm = System.getSecurityManager();
366 final Class<?> caller = Reflection.getCallerClass();
367 if (sm != null) {
368 checkProxyAccess(caller, loader, intfs);
369 }
370
371 return new ProxyBuilder(loader, intfs).build();
372 }
373
374 /*
375 * Check permissions required to create a Proxy class.
376 *
377 * To define a proxy class, it performs the access checks as in
378 * Class.forName (VM will invoke ClassLoader.checkPackageAccess):
379 * 1. "getClassLoader" permission check if loader == null
380 * 2. checkPackageAccess on the interfaces it implements
381 *
382 * To get a constructor and new instance of a proxy class, it performs
383 * the package access check on the interfaces it implements
384 * as in Class.getConstructor.
385 *
386 * If an interface is non-public, the proxy class must be defined by
387 * the defining loader of the interface. If the caller's class loader
388 * is not the same as the defining loader of the interface, the VM
389 * will throw IllegalAccessError when the generated proxy class is
390 * being defined.
391 */
392 private static void checkProxyAccess(Class<?> caller,
393 ClassLoader loader,
394 List<Class<?>> interfaces)
395 {
396 SecurityManager sm = System.getSecurityManager();
397 if (sm != null) {
398 ClassLoader ccl = caller.getClassLoader();
399 if (VM.isSystemDomainLoader(loader) && !VM.isSystemDomainLoader(ccl)) {
400 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
401 }
402 ReflectUtil.checkProxyPackageAccess(ccl, interfaces.toArray(EMPTY_CLASS_ARRAY));
403 }
404 }
405
406 /*
407 * a key used for proxy class with 0 implemented interfaces
408 */
409 private static final Object key0 = new Object();
410
411 /*
412 * Key1 and Key2 are optimized for the common use of dynamic proxies
413 * that implement 1 or 2 interfaces.
414 */
415
416 /*
417 * a key used for proxy class with 1 implemented interface
418 */
419 private static final class Key1 extends WeakReference<Class<?>> {
420 private final int hash;
421
422 Key1(Class<?> intf) {
423 super(intf);
424 this.hash = intf.hashCode();
425 }
426
427 @Override
428 public int hashCode() {
429 return hash;
430 }
431
432 @Override
433 public boolean equals(Object obj) {
434 Class<?> intf;
435 return this == obj ||
436 obj != null &&
437 obj.getClass() == Key1.class &&
438 (intf = get()) != null &&
439 intf == ((Key1) obj).get();
440 }
441 }
442
443 /*
444 * a key used for proxy class with 2 implemented interfaces
445 */
446 private static final class Key2 extends WeakReference<Class<?>> {
447 private final int hash;
448 private final WeakReference<Class<?>> ref2;
449
450 Key2(Class<?> intf1, Class<?> intf2) {
451 super(intf1);
452 hash = 31 * intf1.hashCode() + intf2.hashCode();
453 ref2 = new WeakReference<>(intf2);
454 }
455
456 @Override
457 public int hashCode() {
458 return hash;
459 }
460
461 @Override
462 public boolean equals(Object obj) {
463 Class<?> intf1, intf2;
464 return this == obj ||
465 obj != null &&
466 obj.getClass() == Key2.class &&
467 (intf1 = get()) != null &&
468 intf1 == ((Key2) obj).get() &&
469 (intf2 = ref2.get()) != null &&
470 intf2 == ((Key2) obj).ref2.get();
471 }
472 }
473
474 /*
475 * a key used for proxy class with any number of implemented interfaces
476 * (used here for 3 or more only)
477 */
478 private static final class KeyX {
479 private final int hash;
480 private final WeakReference<Class<?>>[] refs;
481
482 @SuppressWarnings("unchecked")
483 KeyX(List<Class<?>> interfaces) {
484 hash = Arrays.hashCode(interfaces.toArray());
485 refs = (WeakReference<Class<?>>[])new WeakReference<?>[interfaces.size()];
486 int i = 0;
487 for (Class<?> intf : interfaces) {
488 refs[i++] = new WeakReference<>(intf);
489 }
490 }
491
492 @Override
493 public int hashCode() {
494 return hash;
495 }
496
497 @Override
498 public boolean equals(Object obj) {
499 return this == obj ||
500 obj != null &&
501 obj.getClass() == KeyX.class &&
502 equals(refs, ((KeyX) obj).refs);
503 }
504
505 private static boolean equals(WeakReference<Class<?>>[] refs1,
506 WeakReference<Class<?>>[] refs2) {
507 if (refs1.length != refs2.length) {
508 return false;
509 }
510 for (int i = 0; i < refs1.length; i++) {
511 Class<?> intf = refs1[i].get();
512 if (intf == null || intf != refs2[i].get()) {
513 return false;
514 }
515 }
516 return true;
517 }
518 }
519
520 /**
521 * A function that maps an array of interfaces to an optimal key where
522 * Class objects representing interfaces are weakly referenced.
523 */
524 private static final class KeyFactory<T>
525 implements BiFunction<T, List<Class<?>>, Object> {
526 @Override
527 public Object apply(T t, List<Class<?>> interfaces) {
528 switch (interfaces.size()) {
529 case 1: return new Key1(interfaces.get(0)); // the most frequent
530 case 2: return new Key2(interfaces.get(0), interfaces.get(1));
531 case 0: return key0;
532 default: return new KeyX(interfaces);
533 }
534 }
535 }
536
537 /**
538 * A factory function that generates, defines and returns the proxy class
539 * given the ClassLoader and array of interfaces.
540 */
541 private static final class ProxyClassFactory {
542 private static final Unsafe UNSAFE = Unsafe.getUnsafe();
543
544 // prefix for all proxy class names
545 private static final String proxyClassNamePrefix = "$Proxy";
546
547 // next number to use for generation of unique proxy class names
548 private static final AtomicLong nextUniqueNumber = new AtomicLong();
549
550 private static Class<?> defineProxyClass(Module m, List<Class<?>> interfaces) {
551 String proxyPkg = null; // package to define proxy class in
552 int accessFlags = Modifier.PUBLIC | Modifier.FINAL;
553
554 /*
555 * Record the package of a non-public proxy interface so that the
556 * proxy class will be defined in the same package. Verify that
557 * all non-public proxy interfaces are in the same package.
558 */
559 for (Class<?> intf : interfaces) {
560 int flags = intf.getModifiers();
561 if (!Modifier.isPublic(flags)) {
562 accessFlags = Modifier.FINAL; // non-public, final
563 String pkg = intf.getPackageName();
564 if (proxyPkg == null) {
565 proxyPkg = pkg;
566 } else if (!pkg.equals(proxyPkg)) {
567 throw new IllegalArgumentException(
568 "non-public interfaces from different packages");
569 }
570 }
571 }
572
573 if (proxyPkg == null) {
574 // all proxy interfaces are public
575 proxyPkg = m.isNamed() ? PROXY_PACKAGE_NAME + "." + m.getName()
576 : PROXY_PACKAGE_NAME;
577 } else if (proxyPkg.isEmpty() && m.isNamed()) {
578 throw new IllegalArgumentException(
579 "Unnamed package cannot be added to " + m);
580 }
581
582 // add the package to the runtime module if not exists
583 if (m.isNamed() && !Stream.of(m.getPackages()).anyMatch(proxyPkg::equals)) {
584 m.addPackage(proxyPkg);
585 }
586
587 /*
588 * Choose a name for the proxy class to generate.
589 */
590 long num = nextUniqueNumber.getAndIncrement();
591 String proxyName = proxyPkg.isEmpty() ? proxyClassNamePrefix + num
592 : proxyPkg + "." + proxyClassNamePrefix + num;
593
594 ClassLoader loader = getLoader(m);
595 trace(proxyName, m, loader, interfaces);
596
597 /*
598 * Generate the specified proxy class.
599 */
600 byte[] proxyClassFile = ProxyGenerator.generateProxyClass(
601 proxyName, interfaces.toArray(EMPTY_CLASS_ARRAY), accessFlags);
602 try {
603 return UNSAFE.defineClass(proxyName, proxyClassFile, 0, proxyClassFile.length,
604 loader, null);
605 } catch (ClassFormatError e) {
606 /*
607 * A ClassFormatError here means that (barring bugs in the
608 * proxy class generation code) there was some other
609 * invalid aspect of the arguments supplied to the proxy
610 * class creation (such as virtual machine limitations
611 * exceeded).
612 */
613 throw new IllegalArgumentException(e.toString());
614 }
615 }
616
617 /**
618 * Test if the given class is a proxy class
619 */
620 static boolean isProxyClass(Class<?> c) {
621 return proxyCache.containsValue(c);
622 }
623
624 /**
625 * Returns the proxy class. It will return the cached proxy class
626 * if exists; otherwise, it will create the proxy class and store in
627 * the cache.
628 */
629 static Class<?> get(Module module, List<Class<?>> interfaces) {
630 return proxyCache.get(module, interfaces);
631 }
632
633 /**
634 * a cache of proxy classes in the named and unnamed module
635 */
636 private static final WeakCache<Module, List<Class<?>>, Class<?>> proxyCache =
637 new WeakCache<>(new KeyFactory<Module>(),
638 new BiFunction<Module, List<Class<?>>, Class<?>>() {
639 @Override
640 public Class<?> apply(Module m, List<Class<?>> interfaces) {
641 Objects.requireNonNull(m);
642 return defineProxyClass(m, interfaces);
643 }
644 });
645
646
647 private static boolean isExportedType(Class<?> c) {
648 String pn = c.getPackageName();
649 return Modifier.isPublic(c.getModifiers()) && c.getModule().isExported(pn);
650 }
651
652 private static boolean isPackagePrivateType(Class<?> c) {
653 return !Modifier.isPublic(c.getModifiers());
654 }
655
656 private static String toDetails(Class<?> c) {
657 String access = "unknown";
658 if (isExportedType(c)) {
659 access = "exported";
660 } else if (isPackagePrivateType(c)) {
661 access = "package-private";
662 } else {
663 access = "module-private";
664 }
665 ClassLoader ld = c.getClassLoader();
666 return String.format(" %s/%s %s loader %s",
667 c.getModule().getName(), c.getName(), access, ld);
668 }
669
670 static void trace(String cn, Module module, ClassLoader loader, List<Class<?>> interfaces) {
671 if (isDebug()) {
672 System.out.format("PROXY: %s/%s defined by %s%n", module.getName(), cn, loader);
673 }
674 if (isDebug("debug")) {
675 interfaces.stream()
676 .forEach(c -> System.out.println(toDetails(c)));
677 }
678 }
679
680 private static final String DEBUG =
681 AccessController.doPrivileged(new PrivilegedAction<>() {
682 public String run() {
683 return System.getProperty("jdk.proxy.debug", "");
684 }
685 });
686
687 private static final boolean isDebug() {
688 return !DEBUG.isEmpty();
689 }
690 private static final boolean isDebug(String flag) {
691 return DEBUG.equals(flag);
692 }
693 }
694
695 /**
696 * Builder for a proxy class.
697 *
698 * If the module is not specified in this ProxyBuilder constructor,
699 * it will map from the given loader and interfaces to the module
700 * in which the proxy class will be defined.
701 */
702 private static final class ProxyBuilder {
703 final ClassLoader loader;
704 final List<Class<?>> interfaces;
705 final Module module;
706 ProxyBuilder(ClassLoader loader, List<Class<?>> interfaces) {
707 if (!VM.isModuleSystemInited()) {
708 throw new InternalError("Proxy is not supported until module system is fully initialzed");
709 }
710 if (interfaces.size() > 65535) {
711 throw new IllegalArgumentException("interface limit exceeded: " + interfaces.size());
712 }
713
714 Set<Class<?>> refTypes = referencedTypes(loader, interfaces);
715
716 // IAE if violates any restrictions specified in newProxyInstance
717 validateProxyInterfaces(loader, interfaces, refTypes);
718
719 this.loader = loader;
720 this.interfaces = interfaces;
721 this.module = mapToModule(loader, interfaces, refTypes);
722 assert getLoader(module) == loader;
723 }
724
725 /**
726 * Generate a proxy class. If the target module does not have any
727 * to any interface types, IllegalAccessError will be thrown by the VM
728 * at defineClass time.
729 *
730 * Must call the checkProxyAccess method to perform permission checks
731 * before calling this.
732 */
733 Class<?> build() {
734 return ProxyClassFactory.get(module, interfaces);
735 }
736
737 /**
738 * Validate the given proxy interfaces and the given referenced types
739 * are visible to the defining loader.
740 *
741 * @throws IllegalArgumentException if it violates the restrictions specified
742 * in {@link Proxy#newProxyInstance}
743 */
744 static void validateProxyInterfaces(ClassLoader loader,
745 List<Class<?>> interfaces,
746 Set<Class<?>> refTypes)
747 {
748 Map<Class<?>, Boolean> interfaceSet = new IdentityHashMap<>(interfaces.size());
749 for (Class<?> intf : interfaces) {
750 /*
751 * Verify that the class loader resolves the name of this
752 * interface to the same Class object.
753 */
754 ensureVisible(loader, intf);
755
756 /*
757 * Verify that the Class object actually represents an
758 * interface.
759 */
760 if (!intf.isInterface()) {
761 throw new IllegalArgumentException(intf.getName() + " is not an interface");
762 }
763
764 /*
765 * Verify that this interface is not a duplicate.
766 */
767 if (interfaceSet.put(intf, Boolean.TRUE) != null) {
768 throw new IllegalArgumentException("repeated interface: " + intf.getName());
769 }
770 }
771
772 for (Class<?> type : refTypes) {
773 ensureVisible(loader, type);
774 }
775 }
776
777 /*
778 * Returns all types referenced by all public method signatures of
779 * the proxy interfaces
780 */
781 static Set<Class<?>> referencedTypes(ClassLoader loader, List<Class<?>> interfaces) {
782 Set<Class<?>> types = new HashSet<>();
783 for (Class<?> intf : interfaces) {
784 for (Method m : intf.getMethods()) {
785 // return type, parameter types, and exception types
786 Stream.concat(Stream.concat(Stream.of(m.getReturnType()),
787 Arrays.stream(m.getParameterTypes())),
788 Arrays.stream(m.getExceptionTypes()))
789 .map(ProxyBuilder::getElementType)
790 .filter(t -> !t.isPrimitive())
791 .forEach(types::add);
792 }
793 }
794 return types;
795 }
796
797 /**
798 * Returns the module that the generated proxy class belongs to.
799 *
800 * If all proxy interfaces are public and in exported packages,
801 * then the proxy class is in unnamed module.
802 *
803 * If any of proxy interface is package-private, then the proxy class
804 * is in the same module of the package-private interface.
805 *
806 * If all proxy interfaces are public and at least one in a non-exported
807 * package, then the proxy class is in a dynamic module in a non-exported
808 * package. Reads edge and qualified exports are added for
809 * dynamic module to access.
810 */
811 static Module mapToModule(ClassLoader loader, List<Class<?>> interfaces, Set<Class<?>> refTypes) {
812 Map<Class<?>, Module> modulePrivateTypes = new HashMap<>();
813 Map<Class<?>, Module> packagePrivateTypes = new HashMap<>();
814 for (Class<?> intf : interfaces) {
815 Module m = intf.getModule();
816 if (Modifier.isPublic(intf.getModifiers())) {
817 // module-private types
818 if (!m.isExported(intf.getPackageName())) {
819 modulePrivateTypes.put(intf, m);
820 }
821 } else {
822 packagePrivateTypes.put(intf, m);
823 }
824 }
825
826 // all proxy interfaces are public and exported, the proxy class is in unnamed module
827 // Such proxy class is accessible to any unnamed module and named module that
828 // can read unnamed module
829 if (packagePrivateTypes.isEmpty() && modulePrivateTypes.isEmpty()) {
830 return loader != null ? loader.getUnnamedModule() : BootLoader.getUnnamedModule();
831 }
832
833 if (packagePrivateTypes.size() > 0) {
834 // all package-private types must be in the same runtime package
835 // i.e. same package name and same module (named or unnamed)
836 //
837 // Configuration will fail if M1 and in M2 defined by the same loader
838 // and both have the same package p (so no need to check class loader)
839 if (packagePrivateTypes.size() > 1 &&
840 (packagePrivateTypes.keySet().stream() // more than one package
841 .map(Class::getPackageName).distinct().count() > 1 ||
842 packagePrivateTypes.values().stream() // or more than one module
843 .distinct().count() > 1)) {
844 throw new IllegalArgumentException(
845 "non-public interfaces from different packages");
846 }
847
848 // all package-private types are in the same module (named or unnamed)
849 Module target = null;
850 for (Module m : packagePrivateTypes.values()) {
851 if (getLoader(m) != loader) {
852 // the specified loader is not the same class loader of the non-public interface
853 throw new IllegalArgumentException(
854 "non-public interface is not defined by the given loader");
855 }
856 target = m;
857 }
858
859 // validate if the target module can access all other interfaces
860 for (Class<?> intf : interfaces) {
861 Module m = intf.getModule();
862 if (m == target) continue;
863
864 if (!target.canRead(m) || !m.isExported(intf.getPackageName(), target)) {
865 throw new IllegalArgumentException(target + " can't access " + intf.getName());
866 }
867 }
868
869 // return the module of the package-private interface
870 return target;
871 }
872
873 // all proxy interfaces are public and at least one in a non-exported package
874 // map to dynamic proxy module and add reads edge and qualified exports, if necessary
875 Module target = getDynamicModule(loader);
876
877 // set up proxy class access to proxy interfaces and superinterfaces
878 Deque<Class<?>> deque = new LinkedList<>(interfaces);
879 Set<Class<?>> visited = new HashSet<>();
880 while (!deque.isEmpty()) {
881 Class<?> c = deque.poll();
882 if (visited.contains(c)) {
883 continue;
884 }
885 visited.add(c);
886 ensureAccess(target, c);
887
888 // add all superinterfaces
889 for (Class<?> intf : c.getInterfaces()) {
890 deque.add(intf);
891 }
892 }
893
894 // set up proxy class access to types referenced in the method signature
895 refTypes.stream()
896 .filter(t -> !visited.contains(t))
897 .forEach(t -> ensureAccess(target, t));
898 return target;
899 }
900
901 /*
902 * Ensure the given module can access the given class.
903 */
904 static void ensureAccess(Module target, Class<?> c) {
905 Module m = c.getModule();
906 // add read edge and qualified export for the target module to access
907 if (!target.canRead(m)) {
908 Modules.addReads(target, m);
909 }
910 String pn = c.getPackageName();
911 if (!m.isExported(pn, target)) {
912 Modules.addExports(m, pn, target);
913 }
914 }
915
916 /*
917 * Ensure the given class is visible to the class loader.
918 */
919 static void ensureVisible(ClassLoader ld, Class<?> c) {
920 Class<?> type = null;
921 try {
922 type = Class.forName(c.getName(), false, ld);
923 } catch (ClassNotFoundException e) {
924 }
925 if (type != c) {
926 throw new IllegalArgumentException(c.getName() +
927 " referenced from a method is not visible from class loader");
928 }
929 }
930
931 static Class<?> getElementType(Class<?> type) {
932 Class<?> e = type;
933 while (e.isArray()) {
934 e = e.getComponentType();
935 }
936 return e;
937 }
938
939 private static final WeakHashMap<ClassLoader, Module> dynProxyModules = new WeakHashMap<>();
940 private static final AtomicInteger counter = new AtomicInteger();
941
942 /*
943 * Define a dynamic module for the generated proxy classes in a non-exported package
944 * named com.sun.proxy.$MODULE.
945 *
946 * Each class loader will have one dynamic module.
947 */
948 static synchronized Module getDynamicModule(ClassLoader loader) {
949 Module m = dynProxyModules.get(loader);
950 if (m == null) {
951 String mn = "jdk.proxy" + counter.incrementAndGet();
952 String pn = PROXY_PACKAGE_NAME + "." + mn;
953 m = Modules.defineModule(loader, mn, Collections.singleton(pn));
954 Modules.addReads(m, Proxy.class.getModule());
955 // java.base to create proxy instance
956 Modules.addExports(m, pn, Object.class.getModule());
957 dynProxyModules.put(loader, m);
958 }
959 return m;
960 }
961 }
962
963 /**
964 * Returns a proxy instance for the specified interfaces
965 * that dispatches method invocations to the specified invocation
966 * handler.
967 * <p>
968 * <a name="restrictions">{@code IllegalArgumentException} will be thrown
969 * if any of the following restrictions is violated:</a>
970 * <ul>
971 * <li>All of {@code Class} objects in the given {@code interfaces} array
972 * must represent interfaces, not classes or primitive types.
973 *
974 * <li>No two elements in the {@code interfaces} array may
975 * refer to identical {@code Class} objects.
976 *
977 * <li>All of the interface types must be visible by name through the
978 * specified class loader. In other words, for class loader
979 * {@code cl} and every interface {@code i}, the following
980 * expression must be true:<p>
981 * {@code Class.forName(i.getName(), false, cl) == i}
982 *
983 * <li>All of the types referenced by all
984 * public method signatures of the specified interfaces
985 * and those inherited by their superinterfaces
986 * must be visible by name through the specified class loader.
987 *
988 * <li>All non-public interfaces must be in the same package
989 * and module, defined by the specified class loader and
990 * the module of the non-public interfaces can access all of
991 * the interface types; otherwise, it would not be possible for
992 * the proxy class to implement all of the interfaces,
993 * regardless of what package it is defined in.
994 *
995 * <li>For any set of member methods of the specified interfaces
996 * that have the same signature:
997 * <ul>
998 * <li>If the return type of any of the methods is a primitive
999 * type or void, then all of the methods must have that same
1000 * return type.
1001 * <li>Otherwise, one of the methods must have a return type that
1002 * is assignable to all of the return types of the rest of the
1003 * methods.
1004 * </ul>
1005 *
1006 * <li>The resulting proxy class must not exceed any limits imposed
1007 * on classes by the virtual machine. For example, the VM may limit
1008 * the number of interfaces that a class may implement to 65535; in
1009 * that case, the size of the {@code interfaces} array must not
1010 * exceed 65535.
1011 * </ul>
1012 *
1013 * <p>Note that the order of the specified proxy interfaces is
1014 * significant: two requests for a proxy class with the same combination
1015 * of interfaces but in a different order will result in two distinct
1016 * proxy classes.
1017 *
1018 * @param loader the class loader to define the proxy class
1019 * @param interfaces the list of interfaces for the proxy class
1020 * to implement
1021 * @param h the invocation handler to dispatch method invocations to
1022 * @return a proxy instance with the specified invocation handler of a
1023 * proxy class that is defined by the specified class loader
1024 * and that implements the specified interfaces
1025 * @throws IllegalArgumentException if any of the <a href="#restrictions">
1026 * restrictions</a> on the parameters are violated
1027 * @throws SecurityException if a security manager, <em>s</em>, is present
1028 * and any of the following conditions is met:
1029 * <ul>
1030 * <li> the given {@code loader} is {@code null} and
1031 * the caller's class loader is not {@code null} and the
1032 * invocation of {@link SecurityManager#checkPermission
1033 * s.checkPermission} with
1034 * {@code RuntimePermission("getClassLoader")} permission
1035 * denies access;</li>
1036 * <li> for each proxy interface, {@code intf},
1037 * the caller's class loader is not the same as or an
1038 * ancestor of the class loader for {@code intf} and
1039 * invocation of {@link SecurityManager#checkPackageAccess
1040 * s.checkPackageAccess()} denies access to {@code intf};</li>
1041 * <li> any of the given proxy interfaces is non-public and the
1042 * caller class is not in the same {@linkplain Package runtime package}
1043 * as the non-public interface and the invocation of
1044 * {@link SecurityManager#checkPermission s.checkPermission} with
1045 * {@code ReflectPermission("newProxyInPackage.{package name}")}
1046 * permission denies access.</li>
1047 * </ul>
1048 * @throws NullPointerException if the {@code interfaces} array
1049 * argument or any of its elements are {@code null}, or
1050 * if the invocation handler, {@code h}, is
1051 * {@code null}
1052 *
1053 * @see <a href="#membership">Package and Module Membership of Proxy Class</a>
1054 */
1055 @CallerSensitive
1056 public static Object newProxyInstance(ClassLoader loader,
1057 Class<?>[] interfaces,
1058 InvocationHandler h) {
1059 Objects.requireNonNull(h);
1060
1061 final List<Class<?>> intfs = Arrays.asList(interfaces.clone());
1062 final SecurityManager sm = System.getSecurityManager();
1063 final Class<?> caller = Reflection.getCallerClass();
1064 if (sm != null) {
1065 checkProxyAccess(caller, loader, intfs);
1066 }
1067
1068 /*
1069 * Look up or generate the designated proxy class.
1070 */
1071 Class<?> cl = new ProxyBuilder(loader, intfs).build();
1072
1073 return newProxyInstance(cl, caller, h);
1074 }
1075
1076 private static Object newProxyInstance(Class<?> proxyClass, Class<?> caller, InvocationHandler h) {
1077 /*
1078 * Invoke its constructor with the designated invocation handler.
1079 */
1080 try {
1081 final SecurityManager sm = System.getSecurityManager();
1082 if (sm != null) {
1083 checkNewProxyPermission(caller, proxyClass);
1084 }
1085
1086 final Constructor<?> cons = proxyClass.getConstructor(constructorParams);
1087 AccessController.doPrivileged(new PrivilegedAction<Void>() {
1088 public Void run() {
1089 cons.setAccessible(true);
1090 return null;
1091 }
1092 });
1093 return cons.newInstance(new Object[]{h});
1094 } catch (IllegalAccessException | InstantiationException | NoSuchMethodException e) {
1095 throw new InternalError(e.toString(), e);
1096 } catch (InvocationTargetException e) {
1097 Throwable t = e.getCause();
1098 if (t instanceof RuntimeException) {
1099 throw (RuntimeException) t;
1100 } else {
1101 throw new InternalError(t.toString(), t);
1102 }
1103 }
1104 }
1105
1106 // ## this permission check may need to extend for module-private types
1107 private static void checkNewProxyPermission(Class<?> caller, Class<?> proxyClass) {
1108 SecurityManager sm = System.getSecurityManager();
1109 if (sm != null) {
1110 if (ReflectUtil.isNonPublicProxyClass(proxyClass)) {
1111 ClassLoader ccl = caller.getClassLoader();
1112 ClassLoader pcl = proxyClass.getClassLoader();
1113
1114 // do permission check if the caller is in a different runtime package
1115 // of the proxy class
1116 int n = proxyClass.getName().lastIndexOf('.');
1117 String pkg = (n == -1) ? "" : proxyClass.getName().substring(0, n);
1118
1119 n = caller.getName().lastIndexOf('.');
1120 String callerPkg = (n == -1) ? "" : caller.getName().substring(0, n);
1121
1122 if (pcl != ccl || !pkg.equals(callerPkg)) {
1123 sm.checkPermission(new ReflectPermission("newProxyInPackage." + pkg));
1124 }
1125 }
1126 }
1127 }
1128
1129 /**
1130 * Returns the class loader for the given module.
1131 */
1132 private static ClassLoader getLoader(Module m) {
1133 PrivilegedAction<ClassLoader> pa = m::getClassLoader;
1134 return AccessController.doPrivileged(pa);
1135 }
1136
1137 /**
1138 * Returns true if the given class is a proxy class.
1139 *
1140 * @implNote The reliability of this method is important for the ability
1141 * to use it to make security decisions, so its implementation should
1142 * not just test if the class in question extends {@code Proxy}.
1143 *
1144 * @param cl the class to test
1145 * @return {@code true} if the class is a proxy class and
1146 * {@code false} otherwise
1147 * @throws NullPointerException if {@code cl} is {@code null}
1148 */
1149 public static boolean isProxyClass(Class<?> cl) {
1150 return Proxy.class.isAssignableFrom(cl) && ProxyClassFactory.isProxyClass(cl);
1151 }
1152
1153 /**
1154 * Returns the invocation handler for the specified proxy instance.
1155 *
1156 * @param proxy the proxy instance to return the invocation handler for
1157 * @return the invocation handler for the proxy instance
1158 * @throws IllegalArgumentException if the argument is not a
1159 * proxy instance
1160 * @throws SecurityException if a security manager, <em>s</em>, is present
1161 * and the caller's class loader is not the same as or an
1162 * ancestor of the class loader for the invocation handler
1163 * and invocation of {@link SecurityManager#checkPackageAccess
1164 * s.checkPackageAccess()} denies access to the invocation
1165 * handler's class.
1166 */
1167 @CallerSensitive
1168 public static InvocationHandler getInvocationHandler(Object proxy)
1169 throws IllegalArgumentException
1170 {
1171 /*
1172 * Verify that the object is actually a proxy instance.
1173 */
1174 if (!isProxyClass(proxy.getClass())) {
1175 throw new IllegalArgumentException("not a proxy instance");
1176 }
1177
1178 final Proxy p = (Proxy) proxy;
1179 final InvocationHandler ih = p.h;
1180 if (System.getSecurityManager() != null) {
1181 Class<?> ihClass = ih.getClass();
1182 Class<?> caller = Reflection.getCallerClass();
1183 if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(),
1184 ihClass.getClassLoader()))
1185 {
1186 ReflectUtil.checkPackageAccess(ihClass);
1187 }
1188 }
1189
1190 return ih;
1191 }
1192
1193 private static Class<?>[] EMPTY_CLASS_ARRAY = new Class<?>[0];
1194 private static final String PROXY_PACKAGE_NAME = ReflectUtil.PROXY_PACKAGE;
1195 }