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SignatureResolver.kt
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SignatureResolver.kt
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package app.revanced.patcher.signature.resolver
import app.revanced.patcher.PatcherData
import app.revanced.patcher.proxy
import app.revanced.patcher.proxy.ClassProxy
import app.revanced.patcher.signature.MethodSignature
import app.revanced.patcher.signature.PatternScanMethod
import app.revanced.patcher.signature.PatternScanResult
import app.revanced.patcher.signature.SignatureResolverResult
import org.jf.dexlib2.Opcode
import org.jf.dexlib2.iface.ClassDef
import org.jf.dexlib2.iface.Method
import org.jf.dexlib2.iface.instruction.Instruction
import org.jf.dexlib2.iface.instruction.formats.Instruction21c
import org.jf.dexlib2.iface.reference.StringReference
internal class SignatureResolver(
private val classes: List<ClassDef>,
private val methodSignatures: Iterable<MethodSignature>
) {
fun resolve(patcherData: PatcherData) {
for (signature in methodSignatures) {
for (classDef in classes) {
for (method in classDef.methods) {
val patternScanData = compareSignatureToMethod(signature, method) ?: continue
// create class proxy, in case a patch needs mutability
val classProxy = patcherData.proxy(classDef)
signature.result = SignatureResolverResult(
classProxy,
patternScanData,
method.name,
)
}
}
}
}
// These functions do not require the constructor values, so they can be static.
companion object {
fun resolveFromProxy(classProxy: ClassProxy, signature: MethodSignature): SignatureResolverResult? {
for (method in classProxy.immutableClass.methods) {
val result = compareSignatureToMethod(signature, method) ?: continue
return SignatureResolverResult(
classProxy,
result,
method.name,
)
}
return null
}
private fun compareSignatureToMethod(
signature: MethodSignature,
method: Method
): PatternScanResult? {
signature.returnType?.let {
if (!method.returnType.startsWith(signature.returnType)) {
return null
}
}
signature.accessFlags?.let {
if (signature.accessFlags != method.accessFlags) {
return null
}
}
signature.methodParameters?.let {
if (compareParameterTypes(signature.methodParameters, method.parameterTypes)) {
return null
}
}
signature.strings?.let { strings ->
method.implementation ?: return null
method.implementation!!.instructions.let { instructions ->
val stringsList = strings.toMutableList()
for (instruction in instructions) {
if (instruction.opcode != Opcode.CONST_STRING) continue
val string = ((instruction as Instruction21c).reference as StringReference).string
val i = stringsList.indexOfFirst { it == string }
if (i != -1) stringsList.removeAt(i)
}
if (stringsList.isNotEmpty()) return null
}
}
return if (signature.opcodes == null) {
PatternScanResult(0, 0)
} else {
method.implementation?.instructions?.let {
compareOpcodes(signature, it)
}
}
}
private fun compareOpcodes(
signature: MethodSignature,
instructions: Iterable<Instruction>
): PatternScanResult? {
val count = instructions.count()
val pattern = signature.opcodes!!
val size = pattern.count()
val method = signature.metadata.patternScanMethod
val threshold = if (method is PatternScanMethod.Fuzzy)
method.threshold else 0
for (instructionIndex in 0 until count) {
var patternIndex = 0
var currentThreshold = threshold
while (instructionIndex + patternIndex < count) {
val originalOpcode = instructions.elementAt(instructionIndex + patternIndex).opcode
val patternOpcode = pattern.elementAt(patternIndex)
if (
patternOpcode != null && // unknown opcode
originalOpcode != patternOpcode &&
currentThreshold-- == 0
) break
if (++patternIndex < size) continue
patternIndex-- // fix pattern offset
val result = PatternScanResult(instructionIndex, instructionIndex + patternIndex)
if (method is PatternScanMethod.Fuzzy) {
method.warnings = generateWarnings(
signature, instructions, result
)
}
return result
}
}
return null
}
private fun compareParameterTypes(
signature: Iterable<String>,
original: MutableList<out CharSequence>
): Boolean {
return signature.count() != original.size || !(signature.all { a -> original.any { it.startsWith(a) } })
}
private fun generateWarnings(
signature: MethodSignature,
instructions: Iterable<Instruction>,
scanResult: PatternScanResult,
) = buildList {
val pattern = signature.opcodes!!
for ((patternIndex, instructionIndex) in (scanResult.startIndex until scanResult.endIndex).withIndex()) {
val correctOpcode = instructions.elementAt(instructionIndex).opcode
val patternOpcode = pattern.elementAt(patternIndex)
if (
patternOpcode != null && // unknown opcode
correctOpcode != patternOpcode
) {
this.add(
PatternScanMethod.Fuzzy.Warning(
correctOpcode, patternOpcode,
instructionIndex, patternIndex,
)
)
}
}
}
}
}
private operator fun ClassDef.component1() = this
private operator fun ClassDef.component2() = this.methods