Miscellany

import org.apache.bcel.classfile.*;import org.apache.bcel.generic.*;import org.apache.bcel.*;import java.io.*;import java.util.*;public class BCELplay {    JavaClass j;    ClassGen cg;    ConstantPoolGen cp;    InstructionFactory _if;    public static void main(String[] args) {        new BCELplay();    }    public BCELplay() {        try {            w("Parsing HelloWorld.class");            j = new ClassParser("HelloWorld.class").parse();            w("Making ClassGen for HelloWorld.class");            cg = new ClassGen(j);            w("Getting the ConstantPoolGen.");            cp = cg.getConstantPool();            w("Creating Instruction Factory");            InstructionFactory _if = new InstructionFactory(cg, cp);            w("Listing the methods!");            getMethods();            w("Injecting Method");            inject();            w("Dumping the file!");            cg.getJavaClass().dump(new FileOutputStream("HelloWorld.class"));            w("Relisting Methods, seeing if it REALLY injected..");            getMethods1();            w("Injecting into main(), hopeing it works...");            injectInMain();        } catch(Exception e) {            e.printStackTrace();        }    }    public void getMethods() {        for(Method m : cg.getMethods()) {            if(m.getName().equalsIgnoreCase("lol")) {              cg.removeMethod(m);               w("[NOTICE] REMOVED LOL()");            } else                System.out.println("Method in '"+cg.getClassName()+"': "+m);        }    }    public void getMethods1() {        for(Method m : cg.getMethods()) {            System.out.println("Method in '"+cg.getClassName()+"': "+m);        }    }    public void getFields() {        for(Field m : cg.getFields()) {            w("Field in ["+cg.getClassName()+"]: " + m.getName() + " with signature: " + m.getSignature() + " access flags: " + m.getAccessFlags());        }    }    public void getSipushes() {        for(Method m : j.getMethods()) {            if(m.getName().equals("main")) {                w("\tFound main method.");                MethodGen mg = new MethodGen(m, m.getName(), new ConstantPoolGen(m.getConstantPool()));                w("\tCreating InstructionList");                InstructionList il = mg.getInstructionList();                w("\tCreating InstructionHandlek");                InstructionHandle ih = il.getEnd();                InstructionHandle ih2 = ih.getPrev();                while(ih2 != null) {                    Instruction instruction = ih2.getInstruction();                    if(instruction instanceof SIPUSH) {                        SIPUSH push = (SIPUSH)instruction;                        w("SIPUSH: " + push.getValue().intValue());                    }                    ih2 = ih2.getPrev();                }            }        }    }    public void w(String l) {        System.out.println(l);    }    //injectInMain() -- Was gonna try to get a reference into the main method, so it calls the method.    public void injectInMain() {        for(Method m : cg.getMethods()) {            if(m.getName().equalsIgnoreCase("main")) {                Method mainMethod = m;                MethodGen method = new MethodGen(mainMethod, mainMethod.getClass().getName(), cp);                InstructionList il = method.getInstructionList();                il.append(_if.createInvoke("HelloWorld", "lol", Type.VOID, Type.NO_ARGS, Constants.INVOKESPECIAL));                il.setPositions();                method.setInstructionList(il);                method.setMaxStack();                method.setMaxLocals();                cg.replaceMethod(m, method.getMethod());                il.dispose();            }        }    }    public void inject() {        try {            InstructionList il = null;            InstructionFactory factory = new InstructionFactory(cg, cp);            MethodGen method = null;            JavaClass _j = new ClassParser("Methods.class").parse();            ClassGen _cg = new ClassGen(_j);            Method m = null;            for(Method d : _cg.getMethods()) {                if(d.getName().equalsIgnoreCase("lol")) {                    method = new MethodGen(d, d.getClass().getName(), cp);                }            }            if(method != null) il = method.getInstructionList();            InstructionHandle ih_0 = il.append(factory.createFieldAccess("java.lang.System", "out", new ObjectType("java.io.PrintStream"), Constants.GETSTATIC));            il.append(new PUSH(cp, "This is a method i'm adding, oman did it work???"));            il.append(factory.createInvoke("java.io.PrintStream", "println", Type.VOID, new Type[] { Type.STRING }, Constants.INVOKEVIRTUAL));            InstructionHandle ih_8 = il.append(factory.createInvoke("HelloWorld", "sayHai", Type.VOID, Type.NO_ARGS, Constants.INVOKESTATIC));            InstructionHandle ih_11 = il.append(factory.createReturn(Type.VOID));            il.setPositions();            method.setInstructionList(il);            method.setMaxStack();            method.setMaxLocals();            cg.replaceMethod(m, method.getMethod());        } catch(Exception e) {            e.printStackTrace();        }    }}