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// Copyright 2021 Code Intelligence GmbH
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
@file:Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
package com.code_intelligence.jazzer.instrumentor
import com.code_intelligence.jazzer.api.HookType
import com.code_intelligence.jazzer.api.MethodHook
import com.code_intelligence.jazzer.api.MethodHooks
import com.code_intelligence.jazzer.utils.descriptor
import java.lang.invoke.MethodHandle
import java.lang.reflect.Method
import java.lang.reflect.Modifier
class Hook private constructor(hookMethod: Method, annotation: MethodHook) {
// Allowing arbitrary exterior whitespace in the target class name allows for an easy workaround
// for mangled hooks due to shading applied to hooks.
private val targetClassName = annotation.targetClassName.trim()
val targetMethodName = annotation.targetMethod
val targetMethodDescriptor = annotation.targetMethodDescriptor.takeIf { it.isNotEmpty() }
val hookType = annotation.type
val targetInternalClassName = targetClassName.replace('.', '/')
private val targetReturnTypeDescriptor = targetMethodDescriptor?.let { extractReturnTypeDescriptor(it) }
private val targetWrappedReturnTypeDescriptor = targetReturnTypeDescriptor?.let { getWrapperTypeDescriptor(it) }
private val hookClassName: String = hookMethod.declaringClass.name
val hookInternalClassName = hookClassName.replace('.', '/')
val hookMethodName: String = hookMethod.name
val hookMethodDescriptor = hookMethod.descriptor
override fun toString(): String {
return "$hookType $targetClassName.$targetMethodName: $hookClassName.$hookMethodName"
}
companion object {
fun verifyAndGetHook(hookMethod: Method, hookData: MethodHook): Hook {
// Verify the annotation type and extract information for debug statements.
val potentialHook = Hook(hookMethod, hookData)
// Verify the hook method's modifiers (public static).
require(Modifier.isPublic(hookMethod.modifiers)) { "$potentialHook: hook method must be public" }
require(Modifier.isStatic(hookMethod.modifiers)) { "$potentialHook: hook method must be static" }
// Verify the hook method's parameter count.
val numParameters = hookMethod.parameters.size
when (hookData.type) {
HookType.BEFORE, HookType.REPLACE -> require(numParameters == 4) { "$potentialHook: incorrect number of parameters (expected 4)" }
HookType.AFTER -> require(numParameters == 5) { "$potentialHook: incorrect number of parameters (expected 5)" }
}
// Verify the hook method's parameter types.
val parameterTypes = hookMethod.parameterTypes
require(parameterTypes[0] == MethodHandle::class.java) { "$potentialHook: first parameter must have type MethodHandle" }
require(parameterTypes[1] == Object::class.java || parameterTypes[1].name == potentialHook.targetClassName) { "$potentialHook: second parameter must have type Object or ${potentialHook.targetClassName}" }
require(parameterTypes[2] == Array<Object>::class.java) { "$potentialHook: third parameter must have type Object[]" }
require(parameterTypes[3] == Int::class.javaPrimitiveType) { "$potentialHook: fourth parameter must have type int" }
// Verify the hook method's return type if possible.
when (hookData.type) {
HookType.BEFORE, HookType.AFTER -> require(hookMethod.returnType == Void.TYPE) {
"$potentialHook: return type must be void"
}
HookType.REPLACE -> if (potentialHook.targetReturnTypeDescriptor != null) {
val returnTypeDescriptor = hookMethod.returnType.descriptor
if (potentialHook.targetReturnTypeDescriptor == "V") {
require(returnTypeDescriptor == "V") { "$potentialHook: return type must be void to match targetMethodDescriptor" }
} else {
require(
returnTypeDescriptor in listOf(
java.lang.Object::class.java.descriptor,
potentialHook.targetReturnTypeDescriptor,
potentialHook.targetWrappedReturnTypeDescriptor
)
) {
"$potentialHook: return type must have type Object or match the descriptors ${potentialHook.targetReturnTypeDescriptor} or ${potentialHook.targetWrappedReturnTypeDescriptor}"
}
}
}
}
// AfterMethodHook only: Verify the type of the last parameter if known.
if (hookData.type == HookType.AFTER && potentialHook.targetReturnTypeDescriptor != null) {
require(
parameterTypes[4] == java.lang.Object::class.java ||
parameterTypes[4].descriptor == potentialHook.targetWrappedReturnTypeDescriptor
) {
"$potentialHook: fifth parameter must have type Object or match the descriptor ${potentialHook.targetWrappedReturnTypeDescriptor}"
}
}
return potentialHook
}
}
}
fun loadHooks(hookClass: Class<*>): List<Hook> {
val hooks = mutableListOf<Hook>()
for (method in hookClass.methods) {
method.getAnnotation(MethodHook::class.java)?.let { hooks.add(Hook.verifyAndGetHook(method, it)) }
method.getAnnotation(MethodHooks::class.java)?.let {
it.value.forEach { hookAnnotation -> hooks.add(Hook.verifyAndGetHook(method, hookAnnotation)) }
}
}
return hooks
}
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