java - 检测 ApachHttpClient 时出现 ASM 5.2 : Java. lang.linkage 错误

Question

我正在尝试使用 ASM 5.2 来检测依赖关系。由于强制使用 JDK 1.8，我被迫在类编写器中使用 COMPUTE_FRAMES 选项。

当使用默认的 ClassWriter 时，它无法找到某些类并抛出以下异常

java.lang.RuntimeException: java.lang.ClassNotFoundException: XXX
    at org.objectweb.asm.ClassWriter.getCommonSuperClass(Unknown Source)
    at org.objectweb.asm.ClassWriter.a(Unknown Source)
    at org.objectweb.asm.Frame.a(Unknown Source)
    at org.objectweb.asm.Frame.a(Unknown Source)
    at org.objectweb.asm.MethodWriter.visitMaxs(Unknown Source)
    .....

为了解决此问题，我通过创建自定义 classWriter 类并向其传递来自 transform() 的类加载器来重写 ClassWriter 的 getCommonSuperClass() 方法。我遵循了该线程的建议: ASM 5.0.3 With Java 1.8 incorrect maxStack with Java.lang.VerifyError: Operand stack overflow

这是 CustomClassWriter 代码:

class CustomClassWriter extends ClassWriter {


    ClassLoader classLoader;

    public CustomClassWriter(int writerFlag, ClassLoader loader)
    {
        super(writerFlag);
        this.classLoader = loader;
        System.out.println("Trace: Registering class loader from Code injector");
    }

    /**
     * This method returns common super class for both the classes. If no super class
     * is present it returns java/lang/Object class.
     * @param className1
     * @param className2
     * @return The String for the common super class of both the classes
     */
    protected String getCommonSuperClass(String className1, String className2)
    {
        Class class1;
        Class class2;
        //System.out.println("Trace: Default Class loader :" + getClass().getClassLoader().toString());
        ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
        System.out.println("Trace: Context class loader is " + contextClassLoader.toString());
        System.out.println("Trace: Loaded class loaded :" + classLoader.toString());

        try
        {
            class1 = Class.forName(className1.replace('/', '.'), false, this.classLoader);
            class2 = Class.forName(className2.replace('/', '.'), false, this.classLoader);
            System.out.println("Trace: Class 1" + class1.toString());
            System.out.println("Trace: Class 2" + class2.toString());
        }
        catch (Exception th) {
            throw new RuntimeException(th.getMessage());
        }

        if (class1.isAssignableFrom(class2)) {
            return className1;
        }
        if (class2.isAssignableFrom(class1)) {
            return className2;
        }

        if ((class1.isInterface()) || (class2.isInterface())) {
            return "java/lang/Object";
        }

        do {
            class1 = class1.getSuperclass();
        }
        while (!(class1.isAssignableFrom(class2)));
        return class1.getName().replace('.', '/');
    }


}

但是，完成此操作后，当我尝试将 java 代理与 Eureka Netflix 库一起使用时，我遇到了奇怪的问题:

Caused by: java.lang.LinkageError: loader (instance of  sun/misc/Launcher$AppClassLoader): attempted  duplicate class definition for name: "org/apache/http/impl/client/AbstractHttpClient"
    at java.lang.ClassLoader.defineClass1(Native Method) ~[na:1.8.0_144]
    at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[na:1.8.0_144]
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[na:1.8.0_144]
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:467) ~[na:1.8.0_144]
    at java.net.URLClassLoader.access$100(URLClassLoader.java:73) ~[na:1.8.0_144]
    at java.net.URLClassLoader$1.run(URLClassLoader.java:368) ~[na:1.8.0_144]
    at java.net.URLClassLoader$1.run(URLClassLoader.java:362) ~[na:1.8.0_144]
    at java.security.AccessController.doPrivileged(Native Method) ~[na:1.8.0_144]
    at java.net.URLClassLoader.findClass(URLClassLoader.java:361) ~[na:1.8.0_144]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_144]
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) ~[na:1.8.0_144]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_144]
    at java.lang.ClassLoader.defineClass1(Native Method) ~[na:1.8.0_144]
    at java.lang.ClassLoader.defineClass(ClassLoader.java:763) ~[na:1.8.0_144]
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) ~[na:1.8.0_144]
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:467) ~[na:1.8.0_144]
    at java.net.URLClassLoader.access$100(URLClassLoader.java:73) ~[na:1.8.0_144]
    at java.net.URLClassLoader$1.run(URLClassLoader.java:368) ~[na:1.8.0_144]
    at java.net.URLClassLoader$1.run(URLClassLoader.java:362) ~[na:1.8.0_144]
    at java.security.AccessController.doPrivileged(Native Method) ~[na:1.8.0_144]
    at java.net.URLClassLoader.findClass(URLClassLoader.java:361) ~[na:1.8.0_144]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_144]
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) ~[na:1.8.0_144]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_144]
    at com.sun.jersey.client.apache4.ApacheHttpClient4.createDefaultClientHandler(ApacheHttpClient4.java:236) ~[jersey-apache-client4-1.19.1.jar:1.19.1]
    at com.sun.jersey.client.apache4.ApacheHttpClient4.create(ApacheHttpClient4.java:181) ~[jersey-apache-client4-1.19.1.jar:1.19.1]
    at com.netflix.discovery.shared.transport.jersey.EurekaJerseyClientImpl.<init>(EurekaJerseyClientImpl.java:52) ~[eureka-client-1.4.12.jar:1.4.12]
    ... 58 common frames omitted

我不确定这里的确切问题是什么。类加载器如何获取不同的重复定义。有什么方法可以解决这个问题？任何帮助将不胜感激。

编辑:除了上述上下文之外，我已经将 http 客户端依赖项重新打包到自定义命名空间中，以便代理不会检测我们自己的调用。

当我尝试检测 Apache HTTP 客户端时，问题就出现了。目前我有 Apache HTTP Client 4.2 和 4.3 的检测，当我通过删除 4.2 的检测来启动应用程序时，一切正常。

以下是我尝试使用的定义:

private final static String HTTP_CLIENT_43_CLASS_NAME = "org/apache/http/impl/client/InternalHttpClient";
    private final static String HTTP_CLIENT_METHOD_43_NAME = "doExecute";
    private final static String HTTP_CLIENT_METHOD_43_SIGNATURE = "(Lorg/apache/http/HttpHost;Lorg/apache/http/HttpRequest;Lorg/apache/http/protocol/HttpContext;)Lorg/apache/http/client/methods/CloseableHttpResponse;";

    private final static String HTTP_CLIENT_42_CLASS_NAME = "org/apache/http/impl/client/AbstractHttpClient";
    private final static String HTTP_CLIENT_METHOD_42_NAME = "execute";
    private final static String HTTP_CLIENT_METHOD_42_SIGNATURE = "(Lorg/apache/http/HttpHost;Lorg/apache/http/HttpRequest;Lorg/apache/http/protocol/HttpContext;)Lorg/apache/http/HttpResponse;";

Answer 1

问题是您在检测期间使用 ASM 的通用类型解析器加载类。这样，您就可以加载当前正在检测的类。一旦您的检测完成，JVM 就会尝试定义该类，但正如之前定义的那样，这不再可能。

因此，您应该避免在检测期间加载类。