static void writeOriginalCode(NativeCodeGenerator code, byte[] origCode, IntPtr origAddr)
{
for (int i = 0; i < origCode.Length; i++)
{
byte b = origCode[i];
if (b != 0xE8 || i + 5 >= origCode.Length)
{
code.writeByte(b);
continue;
}
IntPtr dest = new IntPtr(origAddr.ToInt64() + i + 5 + BitConverter.ToInt32(origCode, i + 1));
code.writeCall(dest);
i += 4;
}
}
unsafe byte[] createOurCode(IntPtr compileMethod)
{
var code = new NativeCodeGenerator();
var origCode = new byte[0x60];
Marshal.Copy(compileMethod, origCode, 0, origCode.Length);
// our compileMethod() func
int compileMethodOffset = code.Size;
code.writeByte(0xE9);
code.writeDword((uint)origCode.Length);
writeOriginalCode(code, origCode, compileMethod);
int numPushedArgs = compileMethodIsThisCall ? 5 : 6;
code.writeByte(0x51); // push ecx
code.writeByte(0x50); // push eax
code.writeByte(0x54); // push esp
for (int i = 0; i < 5; i++)
{
writePushDwordPtrEspDispl(code, (sbyte)(0xC + numPushedArgs * 4)); // push dword ptr [esp+XXh]
}
if (!compileMethodIsThisCall)
{
writePushDwordPtrEspDispl(code, (sbyte)(0xC + numPushedArgs * 4)); // push dword ptr [esp+XXh]
}
else
{
code.writeByte(0x51); // push ecx
}
code.writeCall(ourCompileMethodInfo.ptr);
code.writeByte(0x5A); // pop edx
code.writeByte(0x59); // pop ecx
code.writeBytes(0x84, 0xD2); // test dl, dl
code.writeBytes(0x74, 0x03); // jz $+5
code.writeBytes(0xC2, (ushort)(numPushedArgs * 4)); // retn 14h/18h
for (int i = 0; i < numPushedArgs; i++)
{
writePushDwordPtrEspDispl(code, (sbyte)(numPushedArgs * 4)); // push dword ptr [esp+XXh]
}
code.writeCall(origCompileMethod);
code.writeBytes(0xC2, (ushort)(numPushedArgs * 4)); // retn 14h/18h
// Our callMethod() code. 1st arg is the method to call. stdcall calling convention.
int callMethodOffset = code.Size;
code.writeByte(0x58); // pop eax (ret addr)
code.writeByte(0x5A); // pop edx (method to call)
if (compileMethodIsThisCall)
{
code.writeByte(0x59); // pop ecx (this ptr)
}
code.writeByte(0x50); // push eax (ret addr)
code.writeBytes(0xFF, 0xE2); // jmp edx
// Returns token of method
int getMethodTokenOffset = code.Size;
code.writeCall(returnMethodTokenInfo.ptr);
code.writeBytes(0xC2, (ushort)(IntPtr.Size * 2));
// Returns name of method
int getMethodNameOffset = code.Size;
code.writeCall(returnNameOfMethodInfo.ptr);
code.writeBytes(0xC2, (ushort)(IntPtr.Size * 3));
IntPtr baseAddr = new IntPtr((byte *)jitterTextFreeMem - code.Size);
ourCompileMethodInfo.ptrInDll = new IntPtr((byte *)baseAddr + compileMethodOffset);
callMethod = new IntPtr((byte *)baseAddr + callMethodOffset);
returnMethodTokenInfo.ptrInDll = new IntPtr((byte *)baseAddr + getMethodTokenOffset);
returnNameOfMethodInfo.ptrInDll = new IntPtr((byte *)baseAddr + getMethodNameOffset);
return(code.getCode(baseAddr));
}
// Writes push dword ptr [esp+displ]
static void writePushDwordPtrEspDispl(NativeCodeGenerator code, sbyte displ)
{
code.writeBytes(0xFF, 0x74);
code.writeBytes(0x24, (byte)displ);
}
unsafe void createOurCode()
{
var code = new NativeCodeGenerator();
// our compileMethod() func
int compileMethodOffset = code.Size;
int numPushedArgs = compileMethodIsThisCall ? 5 : 6;
code.writeByte(0x51); // push ecx
code.writeByte(0x50); // push eax
code.writeByte(0x54); // push esp
for (int i = 0; i < 5; i++)
{
writePushDwordPtrEspDispl(code, (sbyte)(0xC + numPushedArgs * 4)); // push dword ptr [esp+XXh]
}
if (!compileMethodIsThisCall)
{
writePushDwordPtrEspDispl(code, (sbyte)(0xC + numPushedArgs * 4)); // push dword ptr [esp+XXh]
}
else
{
code.writeByte(0x51); // push ecx
}
code.writeCall(ourCompileMethodInfo.ptr);
code.writeByte(0x5A); // pop edx
code.writeByte(0x59); // pop ecx
code.writeBytes(0x84, 0xD2); // test dl, dl
code.writeBytes(0x74, 0x03); // jz $+5
code.writeBytes(0xC2, (ushort)(numPushedArgs * 4)); // retn 14h/18h
for (int i = 0; i < numPushedArgs; i++)
{
writePushDwordPtrEspDispl(code, (sbyte)(numPushedArgs * 4)); // push dword ptr [esp+XXh]
}
code.writeCall(origCompileMethod);
code.writeBytes(0xC2, (ushort)(numPushedArgs * 4)); // retn 14h/18h
// Our callMethod() code. 1st arg is the method to call. stdcall calling convention.
int callMethodOffset = code.Size;
code.writeByte(0x58); // pop eax (ret addr)
code.writeByte(0x5A); // pop edx (method to call)
if (compileMethodIsThisCall)
{
code.writeByte(0x59); // pop ecx (this ptr)
}
code.writeByte(0x50); // push eax (ret addr)
code.writeBytes(0xFF, 0xE2); // jmp edx
// Returns token of method
int getMethodTokenOffset = code.Size;
code.writeCall(returnMethodTokenInfo.ptr);
code.writeBytes(0xC2, (ushort)(IntPtr.Size * 2));
// Returns name of method
int getMethodNameOffset = code.Size;
code.writeCall(returnNameOfMethodInfo.ptr);
code.writeBytes(0xC2, (ushort)(IntPtr.Size * 3));
ourCodeAddr = VirtualAlloc(IntPtr.Zero, new UIntPtr((ulong)code.Size), 0x00001000, PAGE_EXECUTE_READWRITE);
IntPtr baseAddr = ourCodeAddr;
ourCompileMethodInfo.ptrInDll = new IntPtr((byte *)baseAddr + compileMethodOffset);
callMethod = new IntPtr((byte *)baseAddr + callMethodOffset);
returnMethodTokenInfo.ptrInDll = new IntPtr((byte *)baseAddr + getMethodTokenOffset);
returnNameOfMethodInfo.ptrInDll = new IntPtr((byte *)baseAddr + getMethodNameOffset);
byte[] theCode = code.getCode(baseAddr);
Marshal.Copy(theCode, 0, baseAddr, theCode.Length);
}
