de4dot-cex/de4dot.code/deobfuscators/DeobUtils.cs

/*
    Copyright (C) 2011 de4dot@gmail.com

    This file is part of de4dot.

    de4dot is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    de4dot is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with de4dot.  If not, see <http://www.gnu.org/licenses/>.
*/

using System;
using System.IO;
using Mono.Cecil;

namespace de4dot.deobfuscators {
	static class DeobUtils {
		public static void decryptAndAddResources(ModuleDefinition module, string encryptedName, Func<byte[]> decryptResource) {
			Log.v("Decrypting resources, name: {0}", Utils.toCsharpString(encryptedName));
			var decryptedResourceData = decryptResource();
			if (decryptedResourceData == null)
				throw new ApplicationException("decryptedResourceData is null");
			var resourceModule = ModuleDefinition.ReadModule(new MemoryStream(decryptedResourceData));

			Log.indent();
			foreach (var rsrc in resourceModule.Resources) {
				Log.v("Adding decrypted resource {0}", Utils.toCsharpString(rsrc.Name));
				module.Resources.Add(rsrc);
			}
			Log.deIndent();
		}

		public static T lookup<T>(ModuleDefinition module, T def, string errorMessage) where T : MemberReference {
			if (def == null)
				return null;
			var newDef = module.LookupToken(def.MetadataToken.ToInt32()) as T;
			if (newDef == null)
				throw new ApplicationException(errorMessage);
			return newDef;
		}

		// If the file is on the network, and we read more than 2MB, we'll read from the wrong
		// offset in the file! Tested: VMware 8, Win7 x64.
		const int MAX_BYTES_READ = 0x200000;

		public static byte[] readModule(ModuleDefinition module) {
			using (var fileStream = new FileStream(module.FullyQualifiedName, FileMode.Open, FileAccess.Read, FileShare.Read)) {
				var fileData = new byte[(int)fileStream.Length];

				int bytes, offset = 0, length = fileData.Length;
				while ((bytes = fileStream.Read(fileData, offset, System.Math.Min(MAX_BYTES_READ, length - offset))) > 0)
					offset += bytes;
				if (offset != length)
					throw new ApplicationException("Could not read all bytes");

				return fileData;
			}
		}
	}
}