494 lines
15 KiB
C#
494 lines
15 KiB
C#
/*
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Copyright (C) 2011-2012 de4dot@gmail.com
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This file is part of de4dot.
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de4dot is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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de4dot is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with de4dot. If not, see <http://www.gnu.org/licenses/>.
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*/
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using System;
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using System.Collections.Generic;
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using Mono.Cecil;
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using Mono.Cecil.Cil;
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using de4dot.blocks;
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namespace de4dot.code.deobfuscators {
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abstract class ProxyCallFixerBase {
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protected ModuleDefinition module;
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protected List<MethodDefinition> delegateCreatorMethods = new List<MethodDefinition>();
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protected Dictionary<TypeDefinition, bool> delegateTypesDict = new Dictionary<TypeDefinition, bool>();
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protected int errors = 0;
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public int Errors {
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get { return errors; }
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}
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protected class DelegateInfo {
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public MethodReference methodRef; // Method we should call
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public FieldDefinition field; // Field holding the Delegate instance
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public OpCode callOpcode;
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public DelegateInfo(FieldDefinition field, MethodReference methodRef, OpCode callOpcode) {
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this.field = field;
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this.methodRef = methodRef;
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this.callOpcode = callOpcode;
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}
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}
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public int RemovedDelegateCreatorCalls { get; set; }
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public IEnumerable<TypeDefinition> DelegateTypes {
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get { return delegateTypesDict.Keys; }
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}
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public IEnumerable<TypeDefinition> DelegateCreatorTypes {
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get {
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foreach (var method in delegateCreatorMethods)
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yield return method.DeclaringType;
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}
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}
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public bool Detected {
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get { return delegateCreatorMethods.Count != 0; }
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}
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protected ProxyCallFixerBase(ModuleDefinition module) {
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this.module = module;
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}
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protected ProxyCallFixerBase(ModuleDefinition module, ProxyCallFixerBase oldOne) {
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this.module = module;
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foreach (var method in oldOne.delegateCreatorMethods)
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delegateCreatorMethods.Add(lookup(method, "Could not find delegate creator method"));
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foreach (var kv in oldOne.delegateTypesDict)
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delegateTypesDict[lookup(kv.Key, "Could not find delegate type")] = kv.Value;
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}
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protected DelegateInfo copy(DelegateInfo di) {
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var method = lookup(di.methodRef, "Could not find method ref");
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var field = lookup(di.field, "Could not find delegate field");
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return new DelegateInfo(field, method, di.callOpcode);
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}
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protected T lookup<T>(T def, string errorMessage) where T : MemberReference {
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return DeobUtils.lookup(module, def, errorMessage);
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}
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protected void setDelegateCreatorMethod(MethodDefinition delegateCreatorMethod) {
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if (delegateCreatorMethod == null)
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return;
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delegateCreatorMethods.Add(delegateCreatorMethod);
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}
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protected bool isDelegateCreatorMethod(MethodDefinition method) {
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foreach (var m in delegateCreatorMethods) {
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if (m == method)
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return true;
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}
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return false;
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}
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protected virtual IEnumerable<TypeDefinition> getDelegateTypes() {
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foreach (var type in module.Types) {
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if (type.BaseType == null || type.BaseType.FullName != "System.MulticastDelegate")
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continue;
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yield return type;
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}
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}
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protected class BlockInstr {
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public Block Block { get; set; }
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public int Index { get; set; }
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}
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protected class RemoveInfo {
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public int Index { get; set; }
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public DelegateInfo DelegateInfo { get; set; }
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public bool IsCall {
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get { return DelegateInfo != null; }
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}
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}
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protected virtual bool ProxyCallIsObfuscated {
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get { return false; }
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}
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public void deobfuscate(Blocks blocks) {
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if (blocks.Method.DeclaringType != null && delegateTypesDict.ContainsKey(blocks.Method.DeclaringType))
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return;
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var allBlocks = blocks.MethodBlocks.getAllBlocks();
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int loops = ProxyCallIsObfuscated ? 50 : 1;
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for (int i = 0; i < loops; i++) {
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if (!deobfuscate(blocks, allBlocks))
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break;
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}
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deobfuscateEnd(blocks, allBlocks);
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}
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protected abstract bool deobfuscate(Blocks blocks, IList<Block> allBlocks);
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protected virtual void deobfuscateEnd(Blocks blocks, IList<Block> allBlocks) {
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}
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protected static void add(Dictionary<Block, List<RemoveInfo>> removeInfos, Block block, int index, DelegateInfo di) {
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List<RemoveInfo> list;
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if (!removeInfos.TryGetValue(block, out list))
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removeInfos[block] = list = new List<RemoveInfo>();
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list.Add(new RemoveInfo {
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Index = index,
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DelegateInfo = di,
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});
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}
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protected static bool fixProxyCalls(Dictionary<Block, List<RemoveInfo>> removeInfos) {
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foreach (var block in removeInfos.Keys) {
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var list = removeInfos[block];
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var removeIndexes = new List<int>(list.Count);
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foreach (var info in list) {
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if (info.IsCall) {
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var opcode = info.DelegateInfo.callOpcode;
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var newInstr = Instruction.Create(opcode, info.DelegateInfo.methodRef);
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block.replace(info.Index, 1, newInstr);
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}
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else
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removeIndexes.Add(info.Index);
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}
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block.remove(removeIndexes);
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}
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return removeInfos.Count > 0;
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}
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}
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// Fixes proxy calls that call the delegate inline in the code, eg.:
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// ldsfld delegate_instance
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// ...push args...
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// call Invoke
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abstract class ProxyCallFixer1 : ProxyCallFixerBase {
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FieldDefinitionAndDeclaringTypeDict<DelegateInfo> fieldToDelegateInfo = new FieldDefinitionAndDeclaringTypeDict<DelegateInfo>();
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protected ProxyCallFixer1(ModuleDefinition module)
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: base(module) {
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}
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protected ProxyCallFixer1(ModuleDefinition module, ProxyCallFixer1 oldOne)
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: base(module, oldOne) {
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foreach (var key in oldOne.fieldToDelegateInfo.getKeys())
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fieldToDelegateInfo.add(lookup(key, "Could not find field"), copy(oldOne.fieldToDelegateInfo.find(key)));
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}
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protected void addDelegateInfo(DelegateInfo di) {
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fieldToDelegateInfo.add(di.field, di);
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}
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protected DelegateInfo getDelegateInfo(FieldReference field) {
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if (field == null)
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return null;
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return fieldToDelegateInfo.find(field);
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}
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public void find() {
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if (delegateCreatorMethods.Count == 0)
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return;
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Log.v("Finding all proxy delegates");
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foreach (var type in getDelegateTypes()) {
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var cctor = DotNetUtils.getMethod(type, ".cctor");
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if (cctor == null || !cctor.HasBody)
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continue;
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if (!type.HasFields)
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continue;
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object context = checkCctor(type, cctor);
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if (context == null)
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continue;
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Log.v("Found proxy delegate: {0} ({1:X8})", Utils.removeNewlines(type), type.MetadataToken.ToUInt32());
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RemovedDelegateCreatorCalls++;
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Log.indent();
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foreach (var field in type.Fields) {
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if (!field.IsStatic)
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continue;
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MethodReference calledMethod;
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OpCode callOpcode;
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getCallInfo(context, field, out calledMethod, out callOpcode);
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if (calledMethod == null)
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continue;
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addDelegateInfo(new DelegateInfo(field, calledMethod, callOpcode));
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Log.v("Field: {0}, Opcode: {1}, Method: {2} ({3:X8})",
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Utils.removeNewlines(field.Name),
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callOpcode,
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Utils.removeNewlines(calledMethod),
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calledMethod.MetadataToken.ToUInt32());
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}
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Log.deIndent();
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delegateTypesDict[type] = true;
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}
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}
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protected abstract object checkCctor(TypeDefinition type, MethodDefinition cctor);
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protected abstract void getCallInfo(object context, FieldDefinition field, out MethodReference calledMethod, out OpCode callOpcode);
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protected override bool deobfuscate(Blocks blocks, IList<Block> allBlocks) {
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var removeInfos = new Dictionary<Block, List<RemoveInfo>>();
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foreach (var block in allBlocks) {
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var instrs = block.Instructions;
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for (int i = 0; i < instrs.Count; i++) {
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var instr = instrs[i];
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if (instr.OpCode != OpCodes.Ldsfld)
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continue;
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var di = getDelegateInfo(instr.Operand as FieldReference);
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if (di == null)
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continue;
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var callInfo = findProxyCall(di, block, i);
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if (callInfo != null) {
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add(removeInfos, block, i, null);
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add(removeInfos, callInfo.Block, callInfo.Index, di);
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}
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else {
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errors++;
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Log.w("Could not fix proxy call. Method: {0} ({1:X8}), Proxy type: {2} ({3:X8})",
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Utils.removeNewlines(blocks.Method),
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blocks.Method.MetadataToken.ToInt32(),
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Utils.removeNewlines(di.field.DeclaringType),
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di.field.DeclaringType.MetadataToken.ToInt32());
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}
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}
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}
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return fixProxyCalls(removeInfos);
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}
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protected virtual BlockInstr findProxyCall(DelegateInfo di, Block block, int index) {
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return findProxyCall(di, block, index, new Dictionary<Block, bool>(), 1);
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}
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BlockInstr findProxyCall(DelegateInfo di, Block block, int index, Dictionary<Block, bool> visited, int stack) {
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if (visited.ContainsKey(block))
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return null;
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if (index <= 0)
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visited[block] = true;
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var instrs = block.Instructions;
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for (int i = index + 1; i < instrs.Count; i++) {
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if (stack <= 0)
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return null;
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var instr = instrs[i];
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DotNetUtils.updateStack(instr.Instruction, ref stack, false);
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if (stack < 0)
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return null;
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if (instr.OpCode != OpCodes.Call && instr.OpCode != OpCodes.Callvirt) {
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if (stack <= 0)
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return null;
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continue;
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}
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var calledMethod = instr.Operand as MethodReference;
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if (calledMethod == null)
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return null;
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if (stack != (DotNetUtils.hasReturnValue(calledMethod) ? 1 : 0))
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continue;
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if (calledMethod.Name != "Invoke")
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return null;
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return new BlockInstr {
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Block = block,
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Index = i,
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};
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}
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if (stack <= 0)
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return null;
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foreach (var target in block.getTargets()) {
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var info = findProxyCall(di, target, -1, visited, stack);
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if (info != null)
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return info;
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}
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return null;
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}
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protected override void deobfuscateEnd(Blocks blocks, IList<Block> allBlocks) {
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fixBrokenCalls(blocks.Method, allBlocks);
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}
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// The obfuscator could be buggy and call a proxy delegate without pushing the
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// instance field. SA has done it, so let's fix it.
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void fixBrokenCalls(MethodDefinition obfuscatedMethod, IList<Block> allBlocks) {
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foreach (var block in allBlocks) {
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var instrs = block.Instructions;
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for (int i = 0; i < instrs.Count; i++) {
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var call = instrs[i];
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if (call.OpCode != OpCodes.Call && call.OpCode != OpCodes.Callvirt)
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continue;
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var methodRef = call.Operand as MethodReference;
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if (methodRef.Name != "Invoke")
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continue;
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var method = DotNetUtils.getMethod(module, methodRef);
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if (method == null)
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continue;
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var declaringType = DotNetUtils.getType(module, method.DeclaringType);
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if (declaringType == null)
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continue;
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if (!delegateTypesDict.ContainsKey(declaringType))
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continue;
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// Oooops!!! The obfuscator is buggy. Well, let's hope it is, or it's my code. ;)
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Log.w("Holy obfuscator bugs, Batman! Found a proxy delegate call with no instance push in {0:X8}. Replacing it with a throw...", obfuscatedMethod.MetadataToken.ToInt32());
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block.insert(i, Instruction.Create(OpCodes.Ldnull));
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block.replace(i + 1, 1, Instruction.Create(OpCodes.Throw));
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i++;
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}
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}
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}
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}
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// Fixes proxy calls that call a static method which then calls
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// Invoke() on a delegate instance, eg.:
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// ...push args...
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// call static method
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abstract class ProxyCallFixer2 : ProxyCallFixerBase {
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MethodDefinitionAndDeclaringTypeDict<DelegateInfo> proxyMethodToDelegateInfo = new MethodDefinitionAndDeclaringTypeDict<DelegateInfo>();
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protected ProxyCallFixer2(ModuleDefinition module)
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: base(module) {
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}
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protected ProxyCallFixer2(ModuleDefinition module, ProxyCallFixer2 oldOne)
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: base(module, oldOne) {
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foreach (var oldMethod in oldOne.proxyMethodToDelegateInfo.getKeys()) {
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var oldDi = oldOne.proxyMethodToDelegateInfo.find(oldMethod);
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var method = lookup(oldMethod, "Could not find proxy method");
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proxyMethodToDelegateInfo.add(method, copy(oldDi));
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}
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}
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public void find() {
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if (delegateCreatorMethods.Count == 0)
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return;
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Log.v("Finding all proxy delegates");
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foreach (var type in getDelegateTypes()) {
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var cctor = DotNetUtils.getMethod(type, ".cctor");
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if (cctor == null || !cctor.HasBody)
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continue;
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if (!type.HasFields)
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continue;
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object context = checkCctor(type, cctor);
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if (context == null)
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continue;
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Log.v("Found proxy delegate: {0} ({1:X8})", Utils.removeNewlines(type), type.MetadataToken.ToUInt32());
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RemovedDelegateCreatorCalls++;
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var fieldToMethod = getFieldToMethodDictionary(type);
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Log.indent();
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foreach (var field in type.Fields) {
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MethodDefinition proxyMethod;
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if (!fieldToMethod.TryGetValue(field, out proxyMethod))
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continue;
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MethodReference calledMethod;
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OpCode callOpcode;
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getCallInfo(context, field, out calledMethod, out callOpcode);
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if (calledMethod == null)
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continue;
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add(proxyMethod, new DelegateInfo(field, calledMethod, callOpcode));
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Log.v("Field: {0}, Opcode: {1}, Method: {2} ({3:X8})",
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Utils.removeNewlines(field.Name),
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callOpcode,
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Utils.removeNewlines(calledMethod),
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calledMethod.MetadataToken.ToUInt32());
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}
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Log.deIndent();
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delegateTypesDict[type] = true;
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}
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}
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protected void add(MethodDefinition method, DelegateInfo di) {
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proxyMethodToDelegateInfo.add(method, di);
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}
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protected abstract object checkCctor(TypeDefinition type, MethodDefinition cctor);
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protected abstract Dictionary<FieldDefinition, MethodDefinition> getFieldToMethodDictionary(TypeDefinition type);
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protected abstract void getCallInfo(object context, FieldDefinition field, out MethodReference calledMethod, out OpCode callOpcode);
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protected override bool deobfuscate(Blocks blocks, IList<Block> allBlocks) {
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var removeInfos = new Dictionary<Block, List<RemoveInfo>>();
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foreach (var block in allBlocks) {
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var instrs = block.Instructions;
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for (int i = 0; i < instrs.Count; i++) {
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var instr = instrs[i];
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if (instr.OpCode != OpCodes.Call)
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continue;
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var method = instr.Operand as MethodReference;
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if (method == null)
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continue;
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var di = proxyMethodToDelegateInfo.find(method);
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if (di == null)
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continue;
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add(removeInfos, block, i, di);
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}
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}
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return fixProxyCalls(removeInfos);
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}
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}
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// Fixes proxy calls that call a static method with the instance of
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// of a delegate as the last arg, which then calls the Invoke method.
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// ...push args...
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// ldsfld delegate instance
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// call static method
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abstract class ProxyCallFixer3 : ProxyCallFixer1 {
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protected ProxyCallFixer3(ModuleDefinition module)
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: base(module) {
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}
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protected ProxyCallFixer3(ModuleDefinition module, ProxyCallFixer3 oldOne)
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: base(module, oldOne) {
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}
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protected override BlockInstr findProxyCall(DelegateInfo di, Block block, int index) {
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index++;
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if (index >= block.Instructions.Count)
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return null;
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var calledMethod = getCalledMethod(block.Instructions[index]);
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if (calledMethod == null)
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return null;
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return new BlockInstr {
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Block = block,
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Index = index,
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};
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}
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static MethodReference getCalledMethod(Instr instr) {
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if (instr.OpCode.Code != Code.Call)
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return null;
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return instr.Operand as MethodReference;
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}
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}
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}
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