ConstantObfuscator.java

package codechicken.obfuscator;

import codechicken.lib.asm.ObfMapping;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.*;

import java.util.LinkedList;
import java.util.List;

import static org.objectweb.asm.tree.AbstractInsnNode.LDC_INSN;
import static org.objectweb.asm.tree.AbstractInsnNode.METHOD_INSN;

public class ConstantObfuscator implements Opcodes {
    public ObfRemapper obf;
    public List<ObfMapping> descCalls = new LinkedList<ObfMapping>();
    public List<ObfMapping> classCalls = new LinkedList<ObfMapping>();

    public ConstantObfuscator(ObfRemapper obf, String[] a_classCalls, String[] a_descCalls) {
        this.obf = obf;
        for (String callDesc : a_classCalls) {
            classCalls.add(ObfMapping.fromDesc(callDesc));
        }

        for (String callDesc : a_descCalls) {
            descCalls.add(ObfMapping.fromDesc(callDesc));
        }
    }

    public void transform(ClassNode cnode) {
        for (MethodNode method : cnode.methods) {
            for (AbstractInsnNode insn = method.instructions.getFirst(); insn != null; insn = insn.getNext()) {
                obfuscateInsnSeq(insn);
            }
        }
    }

    private void obfuscateInsnSeq(AbstractInsnNode insn) {
        if (matchesClass(insn)) {
            LdcInsnNode node1 = (LdcInsnNode) insn;
            node1.cst = obf.map((String) node1.cst);
        }
        if (matchesDesc(insn)) {
            LdcInsnNode node1 = (LdcInsnNode) insn;
            LdcInsnNode node2 = (LdcInsnNode) node1.getNext();
            LdcInsnNode node3 = (LdcInsnNode) node2.getNext();
            ObfMapping mapping = new ObfMapping((String) node1.cst, (String) node2.cst, (String) node3.cst).map(obf);
            node1.cst = mapping.s_owner;
            node2.cst = mapping.s_name;
            node3.cst = mapping.s_desc;
        }
    }

    private boolean matchesClass(AbstractInsnNode insn) {
        if (insn.getType() != LDC_INSN) {
            return false;
        }
        insn = insn.getNext();
        if (insn == null || insn.getType() != METHOD_INSN) {
            return false;
        }
        for (ObfMapping m : classCalls) {
            if (m.matches((MethodInsnNode) insn)) {
                return true;
            }
        }
        return false;
    }

    private boolean matchesDesc(AbstractInsnNode insn) {
        if (insn.getType() != LDC_INSN) {
            return false;
        }
        insn = insn.getNext();
        if (insn == null || insn.getType() != LDC_INSN) {
            return false;
        }
        insn = insn.getNext();
        if (insn == null || insn.getType() != LDC_INSN) {
            return false;
        }
        insn = insn.getNext();
        if (insn == null || insn.getType() != METHOD_INSN) {
            return false;
        }
        for (ObfMapping m : descCalls) {
            if (m.matches((MethodInsnNode) insn)) {
                return true;
            }
        }
        return false;
    }
}