在C中hook一个Windows API函数通常涉及到使用`DllImport`属性来导入DLL，并使用`SetWindowsHookEx`、`UnhookWindowsHookEx`和`CallNextHookEx`等函数来设置和操作钩子。以下是一个简单的示例，展示如何在C中hook `SetWindowsHookEx`函数：
添加必要的命名空间引用
```csharp
using System;
using System.Runtime.InteropServices;
```
声明`SetWindowsHookEx`函数
```csharp
public static extern IntPtr SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hMod, uint dwThreadId);
```
定义钩子回调函数
```csharp
private static IntPtr HookCallback(int nCode, IntPtr wParam, IntPtr lParam)
{
// 在这里处理钩子事件
Console.WriteLine("Hooked!");
// 调用原函数
return CallNextHookEx(IntPtr.Zero, nCode, wParam, lParam);
}
```
加载DLL并获取函数指针
```csharp
private static IntPtr LoadAndGetProcAddress(string dllName, string functionName)
{
IntPtr pDll = LoadLibrary(dllName);
if (pDll == IntPtr.Zero)
{
Console.WriteLine($"Failed to load {dllName}");
return IntPtr.Zero;
}
IntPtr pAddressOfFunctionToCall = GetProcAddress(pDll, functionName);
if (pAddressOfFunctionToCall == IntPtr.Zero)
{
Console.WriteLine($"Failed to find {functionName} in {dllName}");
FreeLibrary(pDll);
return IntPtr.Zero;
}
return pAddressOfFunctionToCall;
}
private static IntPtr LoadLibrary(string dllToLoad)
{
return LoadLibraryEx(dllToLoad, IntPtr.Zero, LoadLibraryFlags.LOAD_LIBRARY_AS_DATAFILE);
}
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr LoadLibraryEx(string dllToLoad, IntPtr hReservedNull, LoadLibraryFlags dwFlags);
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern IntPtr GetProcAddress(IntPtr hModule, string lpFunctionName);
[DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
private static extern bool FreeLibrary(IntPtr hModule);
private enum LoadLibraryFlags
{
LOAD_LIBRARY_AS_DATAFILE = 0x00000002
}
private delegate IntPtr HookProc(int nCode, IntPtr wParam, IntPtr lParam);
```
