bepin/BepInExTests/TrampolineTests.cs

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System.Runtime.InteropServices;
using BepInEx.IL2CPP;
using Iced.Intel;

namespace BepInEx.Tests
{
	[TestClass]
	public class TrampolineTests
	{
		[DataTestMethod]
		[DataRow(64)]
		[DataRow(32)]
		public void TrampolineTest(int bitness)
		{
			byte[] exampleCode = new byte[] {
				0x48, 0x89, 0x5C, 0x24, 0x10, 0x48, 0x89, 0x74, 0x24, 0x18, 0x55, 0x57, 0x41, 0x56, 0x48, 0x8D,
				0xAC, 0x24, 0x00, 0xFF, 0xFF, 0xFF, 0x48, 0x81, 0xEC, 0x00, 0x02, 0x00, 0x00, 0x48, 0x8B, 0x05,
				0x18, 0x57, 0x0A, 0x00, 0x48, 0x33, 0xC4, 0x48, 0x89, 0x85, 0xF0, 0x00, 0x00, 0x00, 0x4C, 0x8B,
				0x05, 0x2F, 0x24, 0x0A, 0x00, 0x48, 0x8D, 0x05, 0x78, 0x7C, 0x04, 0x00, 0x33, 0xFF
			};

			var exampleCodePointer = Marshal.AllocHGlobal(80);
			var trampolineCodePointer = Marshal.AllocHGlobal(80);
			Marshal.Copy(exampleCode, 0, exampleCodePointer, exampleCode.Length);


			void Disassemble(byte[] data, ulong ip)
			{
				var formatter = new NasmFormatter();
				var output = new StringOutput();
				var codeReader = new ByteArrayCodeReader(data);
				var decoder = Decoder.Create(bitness, codeReader);
				decoder.IP = ip;
				while (codeReader.CanReadByte)
				{
					decoder.Decode(out var instr);
					formatter.Format(instr, output);
					Console.WriteLine($"{instr.IP:X16} {output.ToStringAndReset()}");
				}
				Console.WriteLine();
			}


			Console.WriteLine("Original:");
			Console.WriteLine();


			Disassemble(exampleCode, (ulong)exampleCodePointer.ToInt64());


			int trampolineLength = TrampolineGenerator.Generate(exampleCodePointer, new IntPtr(0xBEEF), trampolineCodePointer, bitness);



			Console.WriteLine("Modified:");
			Console.WriteLine();


			Marshal.Copy(exampleCodePointer, exampleCode, 0, exampleCode.Length);
			Disassemble(exampleCode, (ulong)exampleCodePointer.ToInt64());


			Console.WriteLine();
			Console.WriteLine("Trampoline:");
			Console.WriteLine();

			byte[] trampolineArray = new byte[trampolineLength];
			Marshal.Copy(trampolineCodePointer, trampolineArray, 0, trampolineLength);

			Disassemble(trampolineArray, (ulong)trampolineCodePointer.ToInt64());



			Marshal.FreeHGlobal(exampleCodePointer);
			Marshal.FreeHGlobal(trampolineCodePointer);

			Assert.IsFalse(false);
		}
	}
}