private static void Create(ReverseWrapper <TFunction> reverseFunctionWrapper, nuint functionPtr)
{
var attribute = FunctionAttribute.GetAttribute <TFunction>();
// Hot path: Don't create wrapper if both conventions are already compatible.
var managedFuncAttribute = Misc.TryGetAttributeOrDefault <TFunction, ManagedFunctionAttribute>();
if (managedFuncAttribute != null)
{
if (managedFuncAttribute.Equals(attribute))
{
reverseFunctionWrapper.WrapperPointer = Utilities.CreateJump(functionPtr, false, Constants.MaxAbsJmpSize).ToSigned();
return;
}
reverseFunctionWrapper.WrapperPointer = Wrapper.Create <TFunction>(functionPtr, managedFuncAttribute, attribute).ToSigned();
return;
}
var funcPtrAttribute = Misc.TryGetAttributeOrDefault <TFunction, UnmanagedFunctionPointerAttribute>();
if (!attribute.IsEquivalent(funcPtrAttribute))
{
reverseFunctionWrapper.WrapperPointer = Wrapper.Create <TFunction>(functionPtr, attribute.GetEquivalent(funcPtrAttribute), attribute).ToSigned();
}
else
{
reverseFunctionWrapper.WrapperPointer = Utilities.CreateJump(functionPtr, false, Constants.MaxAbsJmpSize).ToSigned();
}
}
private static void Create(ReverseWrapper <TFunction> reverseFunctionWrapper, IntPtr functionPtr)
{
var attribute = FunctionAttribute.GetAttribute <TFunction>();
// Hot path: Don't create wrapper if both conventions are already compatible.
var managedFuncAttribute = Misc.TryGetAttributeOrDefault <TFunction, ManagedFunctionAttribute>();
if (managedFuncAttribute != null)
{
if (managedFuncAttribute.Equals(attribute))
{
return;
}
reverseFunctionWrapper.WrapperPointer = Wrapper.Create <TFunction>(functionPtr, managedFuncAttribute, attribute);
return;
}
var funcPtrAttribute = Misc.TryGetAttributeOrDefault <TFunction, UnmanagedFunctionPointerAttribute>();
if (!attribute.IsEquivalent(funcPtrAttribute))
{
reverseFunctionWrapper.WrapperPointer = Wrapper.Create <TFunction>(functionPtr, attribute.GetEquivalent(funcPtrAttribute), attribute);
}
}
private static void Create(Hook <TFunction> hook, ReverseWrapper <TFunction> reverseWrapper, long functionAddress, int minHookLength = -1)
{
/*
* === Hook Summary ===
*
* A. Insert Absolute Jump to ReverseWrapper (Convention => CDECL Marshaller)
* A1. Backup original bytes and patch between start and end of JMP for (B).
*
* B. Setup Wrapper to call original function (CDECL => Convention Marshaller)
* B1. Take bytes backed up from A, and create stub function with those
* bytes and JMP to end of hook.
* B2. Assign OriginalFunction to that function stub.
*/
/* Create Convention => CDECL Wrapper. */
List <byte> jumpOpcodes = Utilities.AssembleAbsoluteJump(reverseWrapper.WrapperPointer, false).ToList();
/* Calculate Hook Length (Unless Explicit) */
if (minHookLength == -1)
{
minHookLength = Utilities.GetHookLength((IntPtr)functionAddress, jumpOpcodes.Count, ArchitectureMode.x86_32);
}
// Sometimes our hook can be larger than the amount of bytes taken by the jmp opcode.
// We need to fill the remaining bytes with NOPs.
if (minHookLength > jumpOpcodes.Count)
{
int nopBytes = minHookLength - jumpOpcodes.Count;
for (int x = 0; x < nopBytes; x++)
{
jumpOpcodes.Add(0x90);
}
}
/* Get bytes from original function prologue and patch them. */
CurrentProcess.SafeReadRaw((IntPtr)functionAddress, out byte[] originalFunction, minHookLength);
var functionPatcher = new FunctionPatcher(ArchitectureMode.x86_32);
var functionPatch = functionPatcher.Patch(originalFunction.ToList(), (IntPtr)functionAddress);
IntPtr hookEndAddress = (IntPtr)(functionAddress + minHookLength);
functionPatch.NewFunction.AddRange(Utilities.AssembleAbsoluteJump(hookEndAddress, false));
/* Commit the original modified function to memory. */
byte[] patchedFunction = functionPatch.NewFunction.ToArray();
var buffer = Utilities.FindOrCreateBufferInRange(patchedFunction.Length);
var patchedFunctionAddress = buffer.Add(patchedFunction);
/* Create Hook instance. */
hook.OriginalFunctionAddress = patchedFunctionAddress;
hook.OriginalFunction = Wrapper.Create <TFunction>((long)patchedFunctionAddress);
hook.ReverseWrapper = reverseWrapper;
hook._otherHookPatches = functionPatch.Patches;
hook._hookPatch = new Patch((IntPtr)functionAddress, jumpOpcodes.ToArray());
}
private static void Create(ReverseWrapper <TFunction> reverseFunctionWrapper, IntPtr functionPtr)
{
var reloadedFunctionAttribute = FunctionAttribute.GetAttribute <TFunction>();
// CDECL is hot path, as our TFunction will already be CDECL, we marshal if it's anything else.
if (!reloadedFunctionAttribute.Equals(new FunctionAttribute(CallingConventions.Cdecl)))
{
reverseFunctionWrapper.WrapperPointer = Create(functionPtr, reloadedFunctionAttribute);
}
}
/// <summary>
/// Creates a hook for a function at a given address.
/// </summary>
/// <param name="function">The function to detour the original function to.</param>
/// <param name="functionAddress">The address of the function to hook.</param>
/// <param name="minHookLength">Optional explicit length of hook. Use only in rare cases where auto-length check overflows a jmp/call opcode.</param>
public Hook(TFunction function, long functionAddress, int minHookLength = -1)
{
var reverseWrapper = new ReverseWrapper <TFunction>(function);
Create(this, reverseWrapper, functionAddress, minHookLength);
}