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