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