127 lines
3.4 KiB
C#
127 lines
3.4 KiB
C#
/*
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Copyright (C) 2011-2015 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.Collections.Generic;
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using de4dot.blocks;
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using dnlib.DotNet;
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using dnlib.DotNet.Emit;
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namespace de4dot.code.deobfuscators.CryptoObfuscator {
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class LdnullFixer {
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readonly ModuleDef module;
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readonly InlinedMethodTypes inlinedMethodTypes;
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public LdnullFixer(ModuleDef module, InlinedMethodTypes inlinedMethodTypes) {
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this.module = module;
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this.inlinedMethodTypes = inlinedMethodTypes;
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}
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public void Restore() {
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var fields = FindFieldTypes(FindFieldTypes());
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Restore(fields);
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foreach (var field in fields.Keys)
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inlinedMethodTypes.Add(field.DeclaringType);
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}
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FieldDefAndDeclaringTypeDict<FieldDef> FindFieldTypes() {
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var dict = new FieldDefAndDeclaringTypeDict<FieldDef>();
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foreach (var type in module.GetTypes()) {
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foreach (var method in type.Methods) {
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var body = method.Body;
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if (body == null)
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continue;
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foreach (var instr in body.Instructions) {
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if (instr.OpCode.Code != Code.Ldsfld)
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continue;
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var field = instr.Operand as FieldDef;
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if (field == null)
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continue;
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var declType = field.DeclaringType;
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if (declType == null)
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continue;
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if (!InlinedMethodTypes.IsValidFieldType(declType))
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continue;
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dict.Add(field, field);
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}
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}
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}
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return dict;
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}
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Dictionary<FieldDef, bool> FindFieldTypes(FieldDefAndDeclaringTypeDict<FieldDef> fields) {
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var validFields = new Dictionary<FieldDef, bool>(fields.Count);
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foreach (var field in fields.GetKeys())
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validFields.Add(field, false);
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foreach (var type in module.GetTypes()) {
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if (validFields.Count == 0)
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break;
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foreach (var method in type.Methods) {
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var body = method.Body;
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if (body == null)
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continue;
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foreach (var instr in body.Instructions) {
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if (instr.OpCode.Code == Code.Ldsfld)
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continue;
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var field = instr.Operand as IField;
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if (field == null)
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continue;
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var validType = fields.Find(field);
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if (validType == null)
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continue;
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validFields.Remove(validType);
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}
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}
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}
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return validFields;
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}
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int Restore(Dictionary<FieldDef, bool> nullFields) {
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int numRestored = 0;
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foreach (var type in module.GetTypes()) {
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foreach (var method in type.Methods) {
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var body = method.Body;
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if (body == null)
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continue;
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foreach (var instr in body.Instructions) {
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if (instr.OpCode.Code != Code.Ldsfld)
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continue;
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var field = instr.Operand as FieldDef;
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if (field == null)
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continue;
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if (!nullFields.ContainsKey(field))
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continue;
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instr.OpCode = OpCodes.Ldnull;
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instr.Operand = null;
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numRestored++;
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}
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}
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}
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return numRestored;
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}
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}
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}
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