字节码Bytebuddy拦截java。网服务器socket构造函数
我试图截获java.net.ServerSocket
的两个方法和一个构造函数。
拦截两种方法getLocalPort
和getInetAddress
效果很好。但是,应该处理构造函数ServerSocket(int)
的类不会被触发。我的指令代码(在主项目中包含的另一个jar文件中):
包装检测
public class Instrumenting {
private static final String CLASS_NAME = "java.net.ServerSocket";
public static void instrument(Instrumentation instrumentation) throws Exception {
System.out.println("[Instrumenting] starting to instrument '" + CLASS_NAME + "'");
instrumentation.appendToBootstrapClassLoaderSearch(new JarFile("C:\\Users\\Moritz\\Instrumenting\\dist\\Instrumenting.jar"));
File temp = Files.createTempDirectory("tmp").toFile();
ClassInjector.UsingInstrumentation.of(temp, ClassInjector.UsingInstrumentation.Target.BOOTSTRAP, instrumentation).inject(Collections.singletonMap(
new TypeDescription.ForLoadedType(GetLocalPortIntercept.class),
ClassFileLocator.ForClassLoader.read(GetLocalPortIntercept.class)));
new AgentBuilder.Default()
.ignore(ElementMatchers.none())
.with(new AgentBuilder.InjectionStrategy.UsingInstrumentation(instrumentation, temp))
.type(ElementMatchers.named(CLASS_NAME))
.transform((DynamicType.Builder<?> builder, TypeDescription td, ClassLoader cl, JavaModule jm) ->
builder
.method(ElementMatchers.named("getLocalPort"))
.intercept(MethodDelegation.to(GetLocalPortIntercept.class))
.method(ElementMatchers.named("getInetAddress"))
.intercept(MethodDelegation.to(GetInetAddressIntercept.class))
.constructor(ElementMatchers.takesArguments(1).and(ElementMatchers.takesArguments(Integer.class)))
.intercept(MethodDelegation.to(ServerSocketIntercept.class))
).installOn(instrumentation);
System.out.println("[Instrumenting] done");
}
public static class ServerSocketIntercept {
public static void intercept(int port) throws Exception {
System.out.println("[ServerSocketIntercept] port: " + port);
}
}
public static class GetLocalPortIntercept {
public static int intercept() throws Exception {
System.out.println("[GetLocalPortIntercept]");
return 42;
}
}
public static class GetInetAddressIntercept {
public static InetAddress intercept() throws Exception {
System.out.println("[GetInetAddressIntercept]");
return InetAddress.getByAddress(new byte[] {1, 2, 3 ,4});
}
}
}
它的规模:
import instrumenting.Instrumenting;
...
public class Main {
public static void premain(String agentArgs, Instrumentation instrumentation) throws Exception {
Instrumenting.instrument(instrumentation);
}
public static void main(String[] args) throws MalformedURLException, IOException {
ServerSocket serverSocket = new ServerSocket(12345);
System.out.println("Localport: " + serverSocket.getLocalPort());
System.out.println("InetAddress: " + serverSocket.getInetAddress());
}
}
输出:
[Instrumentation] starting to instrument 'java.net.ServerSocket'
[Instrumentation] done
[GetLocalPortIntercept] Localport: 42
[GetInetAddressIntercept] InetAddress: /1.2.3.4
正如您所看到的,拦截getLocalPort
和getInetAddress
效果很好。但为什么不拦截构造函数
# 1 楼答案
这是因为
ServerSocket
接受int
而不是Integer
。然而,如果您尝试这样做,它将崩溃,因为JVM需要硬编码到任何构造函数中的超级方法调用。您需要在实际拦截之前运行:SuperMethodCall.INSTANCE.andThen(...)
才能使其工作一般来说,我建议您在JVM类上使用
Advice
作为此类引导代理,在这些类中,您可以将代码内联到目标中。它将更加强大