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