[英]Bytebuddy - Intercept java.net.ServerSocket constructor
我試圖攔截java.net.ServerSocket
的兩種方法和一個構造函數。 攔截getLocalPort
和getInetAddress
這兩種方法可以正常工作。 但是,不會觸發應該處理構造函數ServerSocket(int)
的 class。 我要檢測的代碼(在主項目中包含的不同 jar 文件中):
package 儀表;
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});
}
}
}
它是如何命名的:
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());
}
}
output:
[Instrumentation] starting to instrument 'java.net.ServerSocket'
[Instrumentation] done
[GetLocalPortIntercept] Localport: 42
[GetInetAddressIntercept] InetAddress: /1.2.3.4
如您所見,攔截getLocalPort
和getInetAddress
工作正常。 但是為什么構造函數沒有被攔截呢?
這是因為ServerSocket
接受int
而不是Integer
。 但是,如果您嘗試這樣做,它會崩潰,因為 JVM 需要硬編碼到任何構造函數中的超級方法調用。 您需要在實際攔截之前運行: SuperMethodCall.INSTANCE.andThen(...)
以使其工作。
一般來說,我建議您在 JVM 類上使用此類引導代理的Advice
,您可以將代碼內聯到目標中。 它會更健壯。
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