1 /*
2 * Copyright (c) 1999, 2020, 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
43 import jdk.internal.access.JavaLangAccess;
44 import jdk.internal.access.SharedSecrets;
45 import jdk.internal.loader.BootLoader;
46 import jdk.internal.module.Modules;
47 import jdk.internal.misc.VM;
48 import jdk.internal.reflect.CallerSensitive;
49 import jdk.internal.reflect.Reflection;
50 import jdk.internal.loader.ClassLoaderValue;
51 import sun.reflect.misc.ReflectUtil;
52 import sun.security.action.GetBooleanAction;
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 * <h2><a id="membership">Package and Module Membership of Proxy Class</a></h2>
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 id="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
231 * class 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 Module module} of {@code T} is
234 * 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 @java.io.Serial
287 private static final long serialVersionUID = -2222568056686623797L;
288
289 /** parameter types of a proxy class constructor */
290 private static final Class<?>[] constructorParams =
291 { InvocationHandler.class };
292
293 /**
294 * a cache of proxy constructors with
295 * {@link Constructor#setAccessible(boolean) accessible} flag already set
296 */
297 private static final ClassLoaderValue<Constructor<?>> proxyCache =
298 new ClassLoaderValue<>();
299
300 /**
301 * the invocation handler for this proxy instance.
302 * @serial
303 */
304 @SuppressWarnings("serial") // Not statically typed as Serializable
305 protected InvocationHandler h;
306
307 /**
308 * Prohibits instantiation.
309 */
310 private Proxy() {
311 }
312
313 /**
314 * Constructs a new {@code Proxy} instance from a subclass
315 * (typically, a dynamic proxy class) with the specified value
316 * for its invocation handler.
317 *
318 * @param h the invocation handler for this proxy instance
319 *
320 * @throws NullPointerException if the given invocation handler, {@code h},
321 * is {@code null}.
322 */
323 protected Proxy(InvocationHandler h) {
324 Objects.requireNonNull(h);
325 this.h = h;
326 }
327
328 /**
329 * Returns the {@code java.lang.Class} object for a proxy class
330 * given a class loader and an array of interfaces. The proxy class
331 * will be defined by the specified class loader and will implement
332 * all of the supplied interfaces. If any of the given interfaces
333 * is non-public, the proxy class will be non-public. If a proxy class
334 * for the same permutation of interfaces has already been defined by the
335 * class loader, then the existing proxy class will be returned; otherwise,
336 * a proxy class for those interfaces will be generated dynamically
337 * and defined by the class loader.
338 *
339 * @param loader the class loader to define the proxy class
340 * @param interfaces the list of interfaces for the proxy class
341 * to implement
342 * @return a proxy class that is defined in the specified class loader
343 * and that implements the specified interfaces
344 * @throws IllegalArgumentException if any of the <a href="#restrictions">
345 * restrictions</a> on the parameters are violated
346 * @throws SecurityException if a security manager, <em>s</em>, is present
347 * and any of the following conditions is met:
348 * <ul>
349 * <li> the given {@code loader} is {@code null} and
350 * the caller's class loader is not {@code null} and the
351 * invocation of {@link SecurityManager#checkPermission
352 * s.checkPermission} with
353 * {@code RuntimePermission("getClassLoader")} permission
354 * denies access.</li>
355 * <li> for each proxy interface, {@code intf},
356 * the caller's class loader is not the same as or an
357 * ancestor of the class loader for {@code intf} and
358 * invocation of {@link SecurityManager#checkPackageAccess
359 * s.checkPackageAccess()} denies access to {@code intf}.</li>
360 * </ul>
361 * @throws NullPointerException if the {@code interfaces} array
362 * argument or any of its elements are {@code null}
363 *
364 * @deprecated Proxy classes generated in a named module are encapsulated
365 * and not accessible to code outside its module.
366 * {@link Constructor#newInstance(Object...) Constructor.newInstance}
367 * will throw {@code IllegalAccessException} when it is called on
368 * an inaccessible proxy class.
369 * Use {@link #newProxyInstance(ClassLoader, Class[], InvocationHandler)}
370 * to create a proxy instance instead.
371 *
372 * @see <a href="#membership">Package and Module Membership of Proxy Class</a>
373 * @revised 9
374 * @spec JPMS
375 */
376 @Deprecated
377 @CallerSensitive
378 public static Class<?> getProxyClass(ClassLoader loader,
379 Class<?>... interfaces)
380 throws IllegalArgumentException
381 {
382 Class<?> caller = System.getSecurityManager() == null
383 ? null
384 : Reflection.getCallerClass();
385
386 return getProxyConstructor(caller, loader, interfaces)
387 .getDeclaringClass();
388 }
389
390 /**
391 * Returns the {@code Constructor} object of a proxy class that takes a
392 * single argument of type {@link InvocationHandler}, given a class loader
393 * and an array of interfaces. The returned constructor will have the
394 * {@link Constructor#setAccessible(boolean) accessible} flag already set.
395 *
396 * @param caller passed from a public-facing @CallerSensitive method if
397 * SecurityManager is set or {@code null} if there's no
398 * SecurityManager
399 * @param loader the class loader to define the proxy class
400 * @param interfaces the list of interfaces for the proxy class
401 * to implement
402 * @return a Constructor of the proxy class taking single
403 * {@code InvocationHandler} parameter
404 */
405 private static Constructor<?> getProxyConstructor(Class<?> caller,
406 ClassLoader loader,
407 Class<?>... interfaces)
408 {
409 // optimization for single interface
410 if (interfaces.length == 1) {
411 Class<?> intf = interfaces[0];
412 if (caller != null) {
413 checkProxyAccess(caller, loader, intf);
414 }
415 return proxyCache.sub(intf).computeIfAbsent(
416 loader,
417 (ld, clv) -> new ProxyBuilder(ld, clv.key()).build()
418 );
419 } else {
420 // interfaces cloned
421 final Class<?>[] intfsArray = interfaces.clone();
422 if (caller != null) {
423 checkProxyAccess(caller, loader, intfsArray);
424 }
425 final List<Class<?>> intfs = Arrays.asList(intfsArray);
426 return proxyCache.sub(intfs).computeIfAbsent(
427 loader,
428 (ld, clv) -> new ProxyBuilder(ld, clv.key()).build()
429 );
430 }
431 }
432
433 /*
434 * Check permissions required to create a Proxy class.
435 *
436 * To define a proxy class, it performs the access checks as in
437 * Class.forName (VM will invoke ClassLoader.checkPackageAccess):
438 * 1. "getClassLoader" permission check if loader == null
439 * 2. checkPackageAccess on the interfaces it implements
440 *
441 * To get a constructor and new instance of a proxy class, it performs
442 * the package access check on the interfaces it implements
443 * as in Class.getConstructor.
444 *
445 * If an interface is non-public, the proxy class must be defined by
446 * the defining loader of the interface. If the caller's class loader
447 * is not the same as the defining loader of the interface, the VM
448 * will throw IllegalAccessError when the generated proxy class is
449 * being defined.
450 */
451 private static void checkProxyAccess(Class<?> caller,
452 ClassLoader loader,
453 Class<?> ... interfaces)
454 {
455 SecurityManager sm = System.getSecurityManager();
456 if (sm != null) {
457 ClassLoader ccl = caller.getClassLoader();
458 if (loader == null && ccl != null) {
459 sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
460 }
461 ReflectUtil.checkProxyPackageAccess(ccl, interfaces);
462 }
463 }
464
465 /**
466 * Builder for a proxy class.
467 *
468 * If the module is not specified in this ProxyBuilder constructor,
469 * it will map from the given loader and interfaces to the module
470 * in which the proxy class will be defined.
471 */
472 private static final class ProxyBuilder {
473 private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();
474
475 // prefix for all proxy class names
476 private static final String proxyClassNamePrefix = "$Proxy";
477
478 // next number to use for generation of unique proxy class names
479 private static final AtomicLong nextUniqueNumber = new AtomicLong();
480
481 // a reverse cache of defined proxy classes
482 private static final ClassLoaderValue<Boolean> reverseProxyCache =
483 new ClassLoaderValue<>();
484
485 private static Class<?> defineProxyClass(Module m, List<Class<?>> interfaces) {
486 String proxyPkg = null; // package to define proxy class in
487 int accessFlags = Modifier.PUBLIC | Modifier.FINAL;
488
489 /*
490 * Record the package of a non-public proxy interface so that the
491 * proxy class will be defined in the same package. Verify that
492 * all non-public proxy interfaces are in the same package.
493 */
494 for (Class<?> intf : interfaces) {
495 int flags = intf.getModifiers();
496 if (!Modifier.isPublic(flags)) {
497 accessFlags = Modifier.FINAL; // non-public, final
498 String pkg = intf.getPackageName();
499 if (proxyPkg == null) {
500 proxyPkg = pkg;
501 } else if (!pkg.equals(proxyPkg)) {
502 throw new IllegalArgumentException(
503 "non-public interfaces from different packages");
504 }
505 }
506 }
507
508 if (proxyPkg == null) {
509 // all proxy interfaces are public
510 proxyPkg = m.isNamed() ? PROXY_PACKAGE_PREFIX + "." + m.getName()
511 : PROXY_PACKAGE_PREFIX;
512 } else if (proxyPkg.isEmpty() && m.isNamed()) {
513 throw new IllegalArgumentException(
514 "Unnamed package cannot be added to " + m);
515 }
516
517 if (m.isNamed()) {
518 if (!m.getDescriptor().packages().contains(proxyPkg)) {
519 throw new InternalError(proxyPkg + " not exist in " + m.getName());
520 }
521 }
522
523 /*
524 * Choose a name for the proxy class to generate.
525 */
526 long num = nextUniqueNumber.getAndIncrement();
527 String proxyName = proxyPkg.isEmpty()
528 ? proxyClassNamePrefix + num
529 : proxyPkg + "." + proxyClassNamePrefix + num;
530
531 ClassLoader loader = getLoader(m);
532 trace(proxyName, m, loader, interfaces);
533
534 /*
535 * Generate the specified proxy class.
536 */
537 byte[] proxyClassFile = ProxyGenerator.generateProxyClass(loader, proxyName, interfaces, accessFlags);
538 try {
539 Class<?> pc = JLA.defineClass(loader, proxyName, proxyClassFile,
540 null, "__dynamic_proxy__");
541 reverseProxyCache.sub(pc).putIfAbsent(loader, Boolean.TRUE);
542 return pc;
543 } catch (ClassFormatError e) {
544 /*
545 * A ClassFormatError here means that (barring bugs in the
546 * proxy class generation code) there was some other
547 * invalid aspect of the arguments supplied to the proxy
548 * class creation (such as virtual machine limitations
549 * exceeded).
550 */
551 throw new IllegalArgumentException(e.toString());
552 }
553 }
554
555 /**
556 * Test if given class is a class defined by
557 * {@link #defineProxyClass(Module, List)}
558 */
559 static boolean isProxyClass(Class<?> c) {
560 return Objects.equals(reverseProxyCache.sub(c).get(c.getClassLoader()),
561 Boolean.TRUE);
562 }
563
564 private static boolean isExportedType(Class<?> c) {
565 String pn = c.getPackageName();
566 return Modifier.isPublic(c.getModifiers()) && c.getModule().isExported(pn);
567 }
568
569 private static boolean isPackagePrivateType(Class<?> c) {
570 return !Modifier.isPublic(c.getModifiers());
571 }
572
573 private static String toDetails(Class<?> c) {
574 String access = "unknown";
575 if (isExportedType(c)) {
576 access = "exported";
577 } else if (isPackagePrivateType(c)) {
578 access = "package-private";
579 } else {
580 access = "module-private";
581 }
582 ClassLoader ld = c.getClassLoader();
583 return String.format(" %s/%s %s loader %s",
584 c.getModule().getName(), c.getName(), access, ld);
585 }
586
587 static void trace(String cn,
588 Module module,
589 ClassLoader loader,
590 List<Class<?>> interfaces) {
591 if (isDebug()) {
592 System.err.format("PROXY: %s/%s defined by %s%n",
593 module.getName(), cn, loader);
594 }
595 if (isDebug("debug")) {
596 interfaces.forEach(c -> System.out.println(toDetails(c)));
597 }
598 }
599
600 private static final String DEBUG =
601 GetPropertyAction.privilegedGetProperty("jdk.proxy.debug", "");
602
603 private static boolean isDebug() {
604 return !DEBUG.isEmpty();
605 }
606 private static boolean isDebug(String flag) {
607 return DEBUG.equals(flag);
608 }
609
610 // ProxyBuilder instance members start here....
611
612 private final List<Class<?>> interfaces;
613 private final Module module;
614 ProxyBuilder(ClassLoader loader, List<Class<?>> interfaces) {
615 if (!VM.isModuleSystemInited()) {
616 throw new InternalError("Proxy is not supported until "
617 + "module system is fully initialized");
618 }
619 if (interfaces.size() > 65535) {
620 throw new IllegalArgumentException("interface limit exceeded: "
621 + interfaces.size());
622 }
623
624 Set<Class<?>> refTypes = referencedTypes(loader, interfaces);
625
626 // IAE if violates any restrictions specified in newProxyInstance
627 validateProxyInterfaces(loader, interfaces, refTypes);
628
629 this.interfaces = interfaces;
630 this.module = mapToModule(loader, interfaces, refTypes);
631 assert getLoader(module) == loader;
632 }
633
634 ProxyBuilder(ClassLoader loader, Class<?> intf) {
635 this(loader, Collections.singletonList(intf));
636 }
637
638 /**
639 * Generate a proxy class and return its proxy Constructor with
640 * accessible flag already set. If the target module does not have access
641 * to any interface types, IllegalAccessError will be thrown by the VM
642 * at defineClass time.
643 *
644 * Must call the checkProxyAccess method to perform permission checks
645 * before calling this.
646 */
647 Constructor<?> build() {
648 Class<?> proxyClass = defineProxyClass(module, interfaces);
649 final Constructor<?> cons;
650 try {
651 cons = proxyClass.getConstructor(constructorParams);
652 } catch (NoSuchMethodException e) {
653 throw new InternalError(e.toString(), e);
654 }
655 AccessController.doPrivileged(new PrivilegedAction<Void>() {
656 public Void run() {
657 cons.setAccessible(true);
658 return null;
659 }
660 });
661 return cons;
662 }
663
664 /**
665 * Validate the given proxy interfaces and the given referenced types
666 * are visible to the defining loader.
667 *
668 * @throws IllegalArgumentException if it violates the restrictions
669 * specified in {@link Proxy#newProxyInstance}
670 */
671 private static void validateProxyInterfaces(ClassLoader loader,
672 List<Class<?>> interfaces,
673 Set<Class<?>> refTypes)
674 {
675 Map<Class<?>, Boolean> interfaceSet = new IdentityHashMap<>(interfaces.size());
676 for (Class<?> intf : interfaces) {
677 /*
678 * Verify that the class loader resolves the name of this
679 * interface to the same Class object.
680 */
681 ensureVisible(loader, intf);
682
683 /*
684 * Verify that the Class object actually represents an
685 * interface.
686 */
687 if (!intf.isInterface()) {
688 throw new IllegalArgumentException(intf.getName() + " is not an interface");
689 }
690
691 /*
692 * Verify that this interface is not a duplicate.
693 */
694 if (interfaceSet.put(intf, Boolean.TRUE) != null) {
695 throw new IllegalArgumentException("repeated interface: " + intf.getName());
696 }
697 }
698
699 for (Class<?> type : refTypes) {
700 ensureVisible(loader, type);
701 }
702 }
703
704 /*
705 * Returns all types referenced by all public non-static method signatures of
706 * the proxy interfaces
707 */
708 private static Set<Class<?>> referencedTypes(ClassLoader loader,
709 List<Class<?>> interfaces) {
710 var types = new HashSet<Class<?>>();
711 for (var intf : interfaces) {
712 for (Method m : intf.getMethods()) {
713 if (!Modifier.isStatic(m.getModifiers())) {
714 addElementType(types, m.getReturnType());
715 addElementTypes(types, m.getSharedParameterTypes());
716 addElementTypes(types, m.getSharedExceptionTypes());
717 }
718 }
719 }
720 return types;
721 }
722
723 private static void addElementTypes(HashSet<Class<?>> types,
724 Class<?> ... classes) {
725 for (var cls : classes) {
726 addElementType(types, cls);
727 }
728 }
729
730 private static void addElementType(HashSet<Class<?>> types,
731 Class<?> cls) {
732 var type = getElementType(cls);
733 if (!type.isPrimitive()) {
734 types.add(type);
735 }
736 }
737
738 /**
739 * Returns the module that the generated proxy class belongs to.
740 *
741 * If all proxy interfaces are public and in exported packages,
742 * then the proxy class is in unnamed module.
743 *
744 * If any of proxy interface is package-private, then the proxy class
745 * is in the same module of the package-private interface.
746 *
747 * If all proxy interfaces are public and at least one in a non-exported
748 * package, then the proxy class is in a dynamic module in a
749 * non-exported package. Reads edge and qualified exports are added
750 * for dynamic module to access.
751 */
752 private static Module mapToModule(ClassLoader loader,
753 List<Class<?>> interfaces,
754 Set<Class<?>> refTypes) {
755 Map<Class<?>, Module> modulePrivateTypes = new HashMap<>();
756 Map<Class<?>, Module> packagePrivateTypes = new HashMap<>();
757 for (Class<?> intf : interfaces) {
758 Module m = intf.getModule();
759 if (Modifier.isPublic(intf.getModifiers())) {
760 // module-private types
761 if (!m.isExported(intf.getPackageName())) {
762 modulePrivateTypes.put(intf, m);
763 }
764 } else {
765 packagePrivateTypes.put(intf, m);
766 }
767 }
768
769 // all proxy interfaces are public and exported, the proxy class
770 // is in unnamed module. Such proxy class is accessible to
771 // any unnamed module and named module that can read unnamed module
772 if (packagePrivateTypes.isEmpty() && modulePrivateTypes.isEmpty()) {
773 return loader != null ? loader.getUnnamedModule()
774 : BootLoader.getUnnamedModule();
775 }
776
777 if (packagePrivateTypes.size() > 0) {
778 // all package-private types must be in the same runtime package
779 // i.e. same package name and same module (named or unnamed)
780 //
781 // Configuration will fail if M1 and in M2 defined by the same loader
782 // and both have the same package p (so no need to check class loader)
783 if (packagePrivateTypes.size() > 1 &&
784 (packagePrivateTypes.keySet().stream() // more than one package
785 .map(Class::getPackageName).distinct().count() > 1 ||
786 packagePrivateTypes.values().stream() // or more than one module
787 .distinct().count() > 1)) {
788 throw new IllegalArgumentException(
789 "non-public interfaces from different packages");
790 }
791
792 // all package-private types are in the same module (named or unnamed)
793 Module target = null;
794 for (Module m : packagePrivateTypes.values()) {
795 if (getLoader(m) != loader) {
796 // the specified loader is not the same class loader
797 // of the non-public interface
798 throw new IllegalArgumentException(
799 "non-public interface is not defined by the given loader");
800 }
801 target = m;
802 }
803
804 // validate if the target module can access all other interfaces
805 for (Class<?> intf : interfaces) {
806 Module m = intf.getModule();
807 if (m == target) continue;
808
809 if (!target.canRead(m) || !m.isExported(intf.getPackageName(), target)) {
810 throw new IllegalArgumentException(target + " can't access " + intf.getName());
811 }
812 }
813
814 // return the module of the package-private interface
815 return target;
816 }
817
818 // All proxy interfaces are public and at least one in a non-exported
819 // package. So maps to a dynamic proxy module and add reads edge
820 // and qualified exports, if necessary
821 Module target = getDynamicModule(loader);
822
823 // set up proxy class access to proxy interfaces and types
824 // referenced in the method signature
825 Set<Class<?>> types = new HashSet<>(interfaces);
826 types.addAll(refTypes);
827 for (Class<?> c : types) {
828 ensureAccess(target, c);
829 }
830 return target;
831 }
832
833 /*
834 * Ensure the given module can access the given class.
835 */
836 private static void ensureAccess(Module target, Class<?> c) {
837 Module m = c.getModule();
838 // add read edge and qualified export for the target module to access
839 if (!target.canRead(m)) {
840 Modules.addReads(target, m);
841 }
842 String pn = c.getPackageName();
843 if (!m.isExported(pn, target)) {
844 Modules.addExports(m, pn, target);
845 }
846 }
847
848 /*
849 * Ensure the given class is visible to the class loader.
850 */
851 private static void ensureVisible(ClassLoader ld, Class<?> c) {
852 Class<?> type = null;
853 try {
854 type = Class.forName(c.getName(), false, ld);
855 } catch (ClassNotFoundException e) {
856 }
857 if (type != c) {
858 throw new IllegalArgumentException(c.getName() +
859 " referenced from a method is not visible from class loader");
860 }
861 }
862
863 private static Class<?> getElementType(Class<?> type) {
864 Class<?> e = type;
865 while (e.isArray()) {
866 e = e.getComponentType();
867 }
868 return e;
869 }
870
871 private static final ClassLoaderValue<Module> dynProxyModules =
872 new ClassLoaderValue<>();
873 private static final AtomicInteger counter = new AtomicInteger();
874
875 /*
876 * Define a dynamic module for the generated proxy classes in
877 * a non-exported package named com.sun.proxy.$MODULE.
878 *
879 * Each class loader will have one dynamic module.
880 */
881 private static Module getDynamicModule(ClassLoader loader) {
882 return dynProxyModules.computeIfAbsent(loader, (ld, clv) -> {
883 // create a dynamic module and setup module access
884 String mn = "jdk.proxy" + counter.incrementAndGet();
885 String pn = PROXY_PACKAGE_PREFIX + "." + mn;
886 ModuleDescriptor descriptor =
887 ModuleDescriptor.newModule(mn, Set.of(SYNTHETIC))
888 .packages(Set.of(pn))
889 .build();
890 Module m = Modules.defineModule(ld, descriptor, null);
891 Modules.addReads(m, Proxy.class.getModule());
892 // java.base to create proxy instance
893 Modules.addExports(m, pn, Object.class.getModule());
894 return m;
895 });
896 }
897 }
898
899 /**
900 * Returns a proxy instance for the specified interfaces
901 * that dispatches method invocations to the specified invocation
902 * handler.
903 * <p>
904 * <a id="restrictions">{@code IllegalArgumentException} will be thrown
905 * if any of the following restrictions is violated:</a>
906 * <ul>
907 * <li>All of {@code Class} objects in the given {@code interfaces} array
908 * must represent interfaces, not classes or primitive types.
909 *
910 * <li>No two elements in the {@code interfaces} array may
911 * refer to identical {@code Class} objects.
912 *
913 * <li>All of the interface types must be visible by name through the
914 * specified class loader. In other words, for class loader
915 * {@code cl} and every interface {@code i}, the following
916 * expression must be true:<p>
917 * {@code Class.forName(i.getName(), false, cl) == i}
918 *
919 * <li>All of the types referenced by all
920 * public method signatures of the specified interfaces
921 * and those inherited by their superinterfaces
922 * must be visible by name through the specified class loader.
923 *
924 * <li>All non-public interfaces must be in the same package
925 * and module, defined by the specified class loader and
926 * the module of the non-public interfaces can access all of
927 * the interface types; otherwise, it would not be possible for
928 * the proxy class to implement all of the interfaces,
929 * regardless of what package it is defined in.
930 *
931 * <li>For any set of member methods of the specified interfaces
932 * that have the same signature:
933 * <ul>
934 * <li>If the return type of any of the methods is a primitive
935 * type or void, then all of the methods must have that same
936 * return type.
937 * <li>Otherwise, one of the methods must have a return type that
938 * is assignable to all of the return types of the rest of the
939 * methods.
940 * </ul>
941 *
942 * <li>The resulting proxy class must not exceed any limits imposed
943 * on classes by the virtual machine. For example, the VM may limit
944 * the number of interfaces that a class may implement to 65535; in
945 * that case, the size of the {@code interfaces} array must not
946 * exceed 65535.
947 * </ul>
948 *
949 * <p>Note that the order of the specified proxy interfaces is
950 * significant: two requests for a proxy class with the same combination
951 * of interfaces but in a different order will result in two distinct
952 * proxy classes.
953 *
954 * @param loader the class loader to define the proxy class
955 * @param interfaces the list of interfaces for the proxy class
956 * to implement
957 * @param h the invocation handler to dispatch method invocations to
958 * @return a proxy instance with the specified invocation handler of a
959 * proxy class that is defined by the specified class loader
960 * and that implements the specified interfaces
961 * @throws IllegalArgumentException if any of the <a href="#restrictions">
962 * restrictions</a> on the parameters are violated
963 * @throws SecurityException if a security manager, <em>s</em>, is present
964 * and any of the following conditions is met:
965 * <ul>
966 * <li> the given {@code loader} is {@code null} and
967 * the caller's class loader is not {@code null} and the
968 * invocation of {@link SecurityManager#checkPermission
969 * s.checkPermission} with
970 * {@code RuntimePermission("getClassLoader")} permission
971 * denies access;</li>
972 * <li> for each proxy interface, {@code intf},
973 * the caller's class loader is not the same as or an
974 * ancestor of the class loader for {@code intf} and
975 * invocation of {@link SecurityManager#checkPackageAccess
976 * s.checkPackageAccess()} denies access to {@code intf};</li>
977 * <li> any of the given proxy interfaces is non-public and the
978 * caller class is not in the same {@linkplain Package runtime package}
979 * as the non-public interface and the invocation of
980 * {@link SecurityManager#checkPermission s.checkPermission} with
981 * {@code ReflectPermission("newProxyInPackage.{package name}")}
982 * permission denies access.</li>
983 * </ul>
984 * @throws NullPointerException if the {@code interfaces} array
985 * argument or any of its elements are {@code null}, or
986 * if the invocation handler, {@code h}, is
987 * {@code null}
988 *
989 * @see <a href="#membership">Package and Module Membership of Proxy Class</a>
990 * @revised 9
991 * @spec JPMS
992 */
993 @CallerSensitive
994 public static Object newProxyInstance(ClassLoader loader,
995 Class<?>[] interfaces,
996 InvocationHandler h) {
997 Objects.requireNonNull(h);
998
999 final Class<?> caller = System.getSecurityManager() == null
1000 ? null
1001 : Reflection.getCallerClass();
1002
1003 /*
1004 * Look up or generate the designated proxy class and its constructor.
1005 */
1006 Constructor<?> cons = getProxyConstructor(caller, loader, interfaces);
1007
1008 return newProxyInstance(caller, cons, h);
1009 }
1010
1011 private static Object newProxyInstance(Class<?> caller, // null if no SecurityManager
1012 Constructor<?> cons,
1013 InvocationHandler h) {
1014 /*
1015 * Invoke its constructor with the designated invocation handler.
1016 */
1017 try {
1018 if (caller != null) {
1019 checkNewProxyPermission(caller, cons.getDeclaringClass());
1020 }
1021
1022 return cons.newInstance(new Object[]{h});
1023 } catch (IllegalAccessException | InstantiationException e) {
1024 throw new InternalError(e.toString(), e);
1025 } catch (InvocationTargetException e) {
1026 Throwable t = e.getCause();
1027 if (t instanceof RuntimeException) {
1028 throw (RuntimeException) t;
1029 } else {
1030 throw new InternalError(t.toString(), t);
1031 }
1032 }
1033 }
1034
1035 private static void checkNewProxyPermission(Class<?> caller, Class<?> proxyClass) {
1036 SecurityManager sm = System.getSecurityManager();
1037 if (sm != null) {
1038 if (ReflectUtil.isNonPublicProxyClass(proxyClass)) {
1039 ClassLoader ccl = caller.getClassLoader();
1040 ClassLoader pcl = proxyClass.getClassLoader();
1041
1042 // do permission check if the caller is in a different runtime package
1043 // of the proxy class
1044 String pkg = proxyClass.getPackageName();
1045 String callerPkg = caller.getPackageName();
1046
1047 if (pcl != ccl || !pkg.equals(callerPkg)) {
1048 sm.checkPermission(new ReflectPermission("newProxyInPackage." + pkg));
1049 }
1050 }
1051 }
1052 }
1053
1054 /**
1055 * Returns the class loader for the given module.
1056 */
1057 private static ClassLoader getLoader(Module m) {
1058 PrivilegedAction<ClassLoader> pa = m::getClassLoader;
1059 return AccessController.doPrivileged(pa);
1060 }
1061
1062 /**
1063 * Returns true if the given class is a proxy class.
1064 *
1065 * @implNote The reliability of this method is important for the ability
1066 * to use it to make security decisions, so its implementation should
1067 * not just test if the class in question extends {@code Proxy}.
1068 *
1069 * @param cl the class to test
1070 * @return {@code true} if the class is a proxy class and
1071 * {@code false} otherwise
1072 * @throws NullPointerException if {@code cl} is {@code null}
1073 *
1074 * @revised 9
1075 * @spec JPMS
1076 */
1077 public static boolean isProxyClass(Class<?> cl) {
1078 return Proxy.class.isAssignableFrom(cl) && ProxyBuilder.isProxyClass(cl);
1079 }
1080
1081 /**
1082 * Returns the invocation handler for the specified proxy instance.
1083 *
1084 * @param proxy the proxy instance to return the invocation handler for
1085 * @return the invocation handler for the proxy instance
1086 * @throws IllegalArgumentException if the argument is not a
1087 * proxy instance
1088 * @throws SecurityException if a security manager, <em>s</em>, is present
1089 * and the caller's class loader is not the same as or an
1090 * ancestor of the class loader for the invocation handler
1091 * and invocation of {@link SecurityManager#checkPackageAccess
1092 * s.checkPackageAccess()} denies access to the invocation
1093 * handler's class.
1094 */
1095 @CallerSensitive
1096 public static InvocationHandler getInvocationHandler(Object proxy)
1097 throws IllegalArgumentException
1098 {
1099 /*
1100 * Verify that the object is actually a proxy instance.
1101 */
1102 if (!isProxyClass(proxy.getClass())) {
1103 throw new IllegalArgumentException("not a proxy instance");
1104 }
1105
1106 final Proxy p = (Proxy) proxy;
1107 final InvocationHandler ih = p.h;
1108 if (System.getSecurityManager() != null) {
1109 Class<?> ihClass = ih.getClass();
1110 Class<?> caller = Reflection.getCallerClass();
1111 if (ReflectUtil.needsPackageAccessCheck(caller.getClassLoader(),
1112 ihClass.getClassLoader()))
1113 {
1114 ReflectUtil.checkPackageAccess(ihClass);
1115 }
1116 }
1117
1118 return ih;
1119 }
1120
1121 private static final String PROXY_PACKAGE_PREFIX = ReflectUtil.PROXY_PACKAGE;
1122 }