static public void __REPLACE(params byte[] _opcodes)
{
_FuncPtr32 caller = new _FuncPtr32(__TOPCALLER());
//caller.WriteLine();
if (caller.Size < _opcodes.Length) //|| true)
{
//array cannot fit existing allocation
//Console.WriteLine("test");
_FuncPtr32 rebase = new _FuncPtr32(0, _opcodes.Length);
rebase.Array2Image(_opcodes);
rebase.Image2Raw();
rebase.WriteLine();
//Console.WriteLine("test2");
caller.Stream2Image();
caller.Stream((byte)0x68);
caller.Stream((int)rebase);
caller.Stream((byte)0xC3);
//Console.WriteLine("test4");
caller.Image2Raw();
caller.WriteLine();
//Console.WriteLine("test5");
}
else
{
//array can fit
caller.Array2Image(_opcodes);
caller.Image2Raw();
}
//Console.WriteLine("test6");
__DROPSPECIAL((int)caller); //this value is adjusted
//throw new Exception("__REPLACE FAILURE");
}
//this is "magical" rejit class that allows to emit custom assembly into existing managed method
//including operations that are not allowed by C# or default calling convention
//like modification of stackframe, that belongs to other function call
//there are absolutely no safety checks, you can crash entire runtime by single invalid opcode
//also you may cause delayed crash if mess with GC or return pointers
//method will be called like normal, hitting __REPLACE routine will terminate method
//replace it's code with provided sequence
//and RESTART method
//if method can't be replaced, new method will be allocated inside unmanaged memory
//relative calls like E8 and E9 will be patched automatically
//everything else will be left as it is
//you can use __REPLACE(0xC3) inside condition to "nullify" singlerun methods
//also you may put __REPLACE(0xC3) to very end of method with same result
//method will not be changed before actual call into __REPLACE
//obviously, you can't use __REBASE to emic call into rebase, it will cause "problems"
//static unsafe void __REJIT_
static _ReJIT()
{
_FuncPtr32 RETIMM = new _FuncPtr32(typeof(_ReJIT).GetMethod("__TOPCALLER"));
RETIMM.Array2Image
(
0x8B, 0x45, 0x04, //mov eax,DWORD PTR [esp+0x0]
0xC3 //ret
);
RETIMM.Image2Raw();
_FuncPtr32 DROPSPECIAL = new _FuncPtr32(typeof(_ReJIT).GetMethod("__DROPSPECIAL"));
DROPSPECIAL.Array2Image
(
0x8B, 0x44, 0x24, 0x04,
0xC9,
0xC9,
0x50,
0xC3
);
DROPSPECIAL.Image2Raw();
}
static unsafe public void Main(string[] args)
{
Console.WriteLine("Entry:start");
stored_ORIGINAL = new _FuncPtr32(typeof(_yaCIL).GetMethod("ORIGINAL"));
stored_ORIGINAL.Rebase();
stored_ORIGINAL.Rebind();
//this stored copy of ORIGINAL inside unmanaged memory, ready to be invoked
//stored_ORIGINAL.__CALL();
_FuncPtr32 jmp = new _FuncPtr32(typeof(_yaCIL).GetMethod("ORIGINAL"));
_FuncPtr32 gate = new _FuncPtr32(typeof(_yaCIL).GetMethod("__GATE__ORIGINAL"));
jmp.Stream2Image();
jmp.Stream(__arglist((byte)0x68, (int)gate, (byte)0xC3));
jmp.Image2Raw();
//stored_ORIGINAL.__CALL();
int tgtg = ORIGINAL(10);
//Byte[] myAddNativeCodeBytes = new Byte[]
//{
//0x8B, 0x44, 0x24, 0x08, // mov eax,dword ptr [esp+8]
//0x8B, 0x4C, 0x24, 0x04, // mov ecx,dword ptr [esp+4]
//0x03, 0xC1, // add eax,ecx
//0xC2, 0x08, 0x00 // ret 8
//};
//IntPtr myAddNativeCodeBytesPtr =
//Marshal.AllocHGlobal(myAddNativeCodeBytes.Length);
//Marshal.Copy(myAddNativeCodeBytes, 0,
//myAddNativeCodeBytesPtr, myAddNativeCodeBytes.Length);
//MyAdd myAdd = (MyAdd)Marshal.GetDelegateForFunctionPointer(
//myAddNativeCodeBytesPtr, typeof(MyAdd));
//Int32 result = myAdd(4, 5);
// Did it work?
//Console.WriteLine("Result: {0}", result);
//Console.WriteLine(tgtg);
Console.WriteLine("Entry:complete");
}