Add initial static field scrambling support

master
Graham 5 years ago
parent ce74765269
commit 9089fe834a
  1. 131
      deob/src/main/java/dev/openrs2/deob/transform/StaticScramblingTransformer.kt

@ -4,26 +4,53 @@ import dev.openrs2.asm.ClassVersionUtils
import dev.openrs2.asm.MemberRef
import dev.openrs2.asm.classpath.ClassPath
import dev.openrs2.asm.classpath.Library
import dev.openrs2.asm.getExpression
import dev.openrs2.asm.sequential
import dev.openrs2.asm.transform.Transformer
import dev.openrs2.deob.remap.TypedRemapper
import org.objectweb.asm.Opcodes
import org.objectweb.asm.tree.AbstractInsnNode
import org.objectweb.asm.tree.ClassNode
import org.objectweb.asm.tree.FieldInsnNode
import org.objectweb.asm.tree.FieldNode
import org.objectweb.asm.tree.InsnList
import org.objectweb.asm.tree.InsnNode
import org.objectweb.asm.tree.MethodInsnNode
import org.objectweb.asm.tree.MethodNode
import kotlin.math.max
class StaticScramblingTransformer : Transformer() {
private val fields = mutableMapOf<MemberRef, String>()
private val methods = mutableMapOf<MemberRef, String>()
private data class Field(val node: FieldNode, val initializer: InsnList, val version: Int, val maxStack: Int) {
val dependencies = initializer.asSequence()
.filterIsInstance<FieldInsnNode>()
.filter { it.opcode == Opcodes.GETSTATIC }
.map(::MemberRef)
.toSet()
}
private val fields = mutableMapOf<MemberRef, Field>()
private val fieldClasses = mutableMapOf<MemberRef, String>()
private val methodClasses = mutableMapOf<MemberRef, String>()
private var nextStaticClass: ClassNode? = null
private var nextClinit: MethodNode? = null
private val staticClasses = mutableListOf<ClassNode>()
private fun nextClass(): ClassNode {
private fun nextClass(): Pair<ClassNode, MethodNode> {
var clazz = nextStaticClass
if (clazz != null && (clazz.fields.size + clazz.methods.size) < MAX_FIELDS_AND_METHODS) {
return clazz
return Pair(clazz, nextClinit!!)
}
val clinit = MethodNode()
clinit.access = Opcodes.ACC_STATIC
clinit.name = "<clinit>"
clinit.desc = "()V"
clinit.exceptions = mutableListOf()
clinit.parameters = mutableListOf()
clinit.instructions = InsnList()
clinit.instructions.add(InsnNode(Opcodes.RETURN))
clinit.tryCatchBlocks = mutableListOf()
clazz = ClassNode()
clazz.version = Opcodes.V1_1
clazz.access = Opcodes.ACC_PUBLIC or Opcodes.ACC_SUPER
@ -32,17 +59,72 @@ class StaticScramblingTransformer : Transformer() {
clazz.interfaces = mutableListOf()
clazz.innerClasses = mutableListOf()
clazz.fields = mutableListOf()
clazz.methods = mutableListOf()
clazz.methods = mutableListOf(clinit)
staticClasses += clazz
nextStaticClass = clazz
nextClinit = clinit
return Pair(clazz, clinit)
}
private fun extractInitializers(clazz: ClassNode, clinit: MethodNode, block: List<AbstractInsnNode>) {
val putstatics = block.filterIsInstance<FieldInsnNode>()
.filter { it.opcode == Opcodes.PUTSTATIC }
for (putstatic in putstatics) {
if (putstatic.owner != clazz.name || putstatic.name in TypedRemapper.EXCLUDED_FIELDS) {
continue
}
val node = clazz.fields.find { it.name == putstatic.name && it.desc == putstatic.desc } ?: continue
// TODO(gpe): use a filter here (pure with no *LOADs?)
val expr = getExpression(putstatic) ?: continue
val initializer = InsnList()
for (insn in expr) {
clinit.instructions.remove(insn)
initializer.add(insn)
}
clinit.instructions.remove(putstatic)
initializer.add(putstatic)
clazz.fields.remove(node)
val ref = MemberRef(putstatic)
fields[ref] = Field(node, initializer, clazz.version, clinit.maxStack)
}
}
return clazz
private fun spliceInitializers() {
val done = mutableSetOf<MemberRef>()
for ((ref, field) in fields) {
spliceInitializers(done, ref, field)
}
}
private fun spliceInitializers(done: MutableSet<MemberRef>, ref: MemberRef, field: Field) {
if (!done.add(ref)) {
return
}
for (dependency in field.dependencies) {
spliceInitializers(done, dependency, fields[dependency]!!)
}
val (clazz, clinit) = nextClass()
clazz.fields.add(field.node)
clazz.version = ClassVersionUtils.maxVersion(clazz.version, field.version)
clinit.instructions.insertBefore(clinit.instructions.last, field.initializer)
clinit.maxStack = max(clinit.maxStack, field.maxStack)
fieldClasses[ref] = clazz.name
}
override fun preTransform(classPath: ClassPath) {
fields.clear()
methods.clear()
fieldClasses.clear()
methodClasses.clear()
nextStaticClass = null
staticClasses.clear()
@ -58,6 +140,31 @@ class StaticScramblingTransformer : Transformer() {
continue
}
val clinit = clazz.methods.find { it.name == "<clinit>" }
if (clinit != null) {
val insns = clinit.instructions.toMutableList()
/*
* Most (or all?) of the <clinit> methods have "simple"
* initializers that we're capable of moving in the first
* and last basic blocks of the method. The last basic
* block is always at the end of the code and ends in a
* RETURN. This allows us to avoid worrying about making a
* full basic block control flow graph here.
*/
val entry = insns.takeWhile { it.sequential }
extractInitializers(clazz, clinit, entry)
val last = insns.lastOrNull()
if (last != null && last.opcode == Opcodes.RETURN) {
insns.removeAt(insns.size - 1)
val exit = insns.takeLastWhile { it.sequential }
extractInitializers(clazz, clinit, exit)
}
}
clazz.methods.removeIf { method ->
if (method.access and Opcodes.ACC_STATIC == 0) {
return@removeIf false
@ -67,15 +174,17 @@ class StaticScramblingTransformer : Transformer() {
return@removeIf false
}
val staticClass = nextClass()
val (staticClass, _) = nextClass()
staticClass.methods.add(method)
staticClass.version = ClassVersionUtils.maxVersion(staticClass.version, clazz.version)
methods[MemberRef(clazz, method)] = staticClass.name
methodClasses[MemberRef(clazz, method)] = staticClass.name
return@removeIf true
}
}
spliceInitializers()
for (clazz in staticClasses) {
library.add(clazz)
}
@ -85,8 +194,8 @@ class StaticScramblingTransformer : Transformer() {
override fun transformCode(classPath: ClassPath, library: Library, clazz: ClassNode, method: MethodNode): Boolean {
for (insn in method.instructions) {
when (insn) {
is FieldInsnNode -> insn.owner = fields.getOrDefault(MemberRef(insn), insn.owner)
is MethodInsnNode -> insn.owner = methods.getOrDefault(MemberRef(insn), insn.owner)
is FieldInsnNode -> insn.owner = fieldClasses.getOrDefault(MemberRef(insn), insn.owner)
is MethodInsnNode -> insn.owner = methodClasses.getOrDefault(MemberRef(insn), insn.owner)
}
}

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