C#屏蔽系统热键Ctrl+Alt+Delete的代码尝试。(已修改bug)
C#屏蔽系统热键Ctrl+Alt+Delete的代码尝试。
2011.08.05 （七夕前一天）
最近在做一款小软件，需要锁定用户的输入，包括系统热键（Ctrl+Alt+Delete)，在网络中寻找良久，发现这些不错的代码。
经过仔细整理，现将这些代码公布，有兴趣的拿去用用。
搜集的过程有些艰辛，从VB6，到VB.NET，到我熟悉的C#。
一、思路分析。
1. 在窗体类Form中，重载消息循环WndProc来实现功能按键的屏蔽
protected override void WndProc(ref Message m)
{
//ToDo:根据m.Msg来处理你要的按键
base.WndProc(ref m);
}
优点：可以屏蔽大部分按键。使用简单。
缺点：不能注册全局热键，对系统级的热键无效，比如：a. Ctrl+Esc, b. Ctrl+Shift+Esc,
c. Alt+Tab, d. Alt+Esc, e. Ctrl+Alt+Delete
类似的方法有System.Windows.Forms.Control的KeyPress,KeyDown事件，
2.利用钩子技术，这个可以捕获大多数键盘消息，但对Ctrl+Alt+Delete仍然无效。
3.最后发现一份VB6写的代码，提到这个方案：
锁定 Ctrl+Alt+Del 使用远程线程、代码注入及子类化技术。
普通键盘消息，使用普通钩子技术”
虽然这些我都还不太懂，但总算把代码移植到了.NET环境下，功能是实现了。
二、代码分析
第一步：包装Win32 API
User32.dll,
user32.dll
1 [DllImport("user32.dll", CallingConvention = CallingConvention.StdCall)]
2 public static extern IntPtr SetWindowsHookEx(int hookType, HookProc lpfn, IntPtr pInstance, int threadId);
3
4 [DllImport("user32.dll", CallingConvention = CallingConvention.StdCall)]
5 public static extern bool UnhookWindowsHookEx(IntPtr pHookHandle);
6
7 [DllImport("user32.dll", CallingConvention = CallingConvention.StdCall)]
8 public static extern int CallNextHookEx(IntPtr pHookHandle, int nCode, int wParam, IntPtr lParam);
9
10 [DllImport("user32.dll")]
11 public static extern bool BlockInput(bool fBlockIt);
Kernel32.dll,
View Code
1 [DllImport("kernel32.dll")]
2 public static extern IntPtr OpenProcess(ProcessAccessFlags dwDesiredAccess,
3 [MarshalAs(UnmanagedType.Bool)] bool bInheritHandle,
4 int dwProcessId);
5 [DllImport("kernel32.dll", SetLastError = true)]
6 public static extern bool ReadProcessMemory(
7 IntPtr hProcess,
8 IntPtr lpBaseAddress,
9 [Out] byte[] lpBuffer,
10 int dwSize,
11 out int lpNumberOfBytesRead
12 );
13 [DllImport("kernel32.dll", SetLastError = true)]
14 public static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, uint[] lpBuffer, uint nSize, out int lpNumberOfBytesWritten);
15
16
17 [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
18 public static extern ushort GlobalAddAtom(string lpString);
19 [DllImport("kernel32.dll", SetLastError = true, ExactSpelling = true)]
20 public static extern ushort GlobalDeleteAtom(ushort nAtom);
21 [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto, EntryPoint = "GlobalFindAtomW")]
22 public static extern ushort GlobalFindAtom(string lpString);
23
24
25 [DllImport("kernel32.dll", SetLastError = true)]
26 public static extern IntPtr CreateToolhelp32Snapshot(SnapshotFlags dwFlags, uint th32ProcessID);
27 [DllImport("kernel32.dll", EntryPoint = "Process32FirstW")]
28 public static extern bool Process32First(IntPtr hSnapshot, ref PROCESSENTRY32 lppe);
29 [DllImport("kernel32.dll", EntryPoint = "Process32NextW")]
30 public static extern bool Process32Next(IntPtr hSnapshot, ref PROCESSENTRY32 lppe);
31
32
33 [DllImport("kernel32.dll", SetLastError = true)]
34 [return: MarshalAs(UnmanagedType.Bool)]
35 public static extern bool CloseHandle(IntPtr hObject);
36 [DllImport("kernel32.dll")]
37 public static extern IntPtr GetCurrentProcess();
38
39
40 [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
41 public static extern IntPtr GetModuleHandle(string lpModuleName);
42 [DllImport("kernel32.dll", CharSet = CharSet.Ansi, ExactSpelling = true, SetLastError = true)]
43 public static extern UIntPtr GetProcAddress(IntPtr hModule, string procName);
44 [DllImport("kernel32.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
45 public static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress, uint dwSize, AllocationType flAllocationType, MemoryProtection flProtect);
46 [DllImport("kernel32.dll", SetLastError = true, ExactSpelling = true)]
47 public static extern bool VirtualFreeEx(IntPtr hProcess, IntPtr lpAddress, int dwSize, FreeType dwFreeType);
48
49
50 [DllImport("kernel32.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
51 public static extern IntPtr CreateRemoteThread(IntPtr hProcess, IntPtr lpThreadAttributes, uint dwStackSize, int lpStartAddress, IntPtr lpParameter, uint dwCreationFlags, out IntPtr lpThreadId);
52 [DllImport("kernel32.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
53 public static extern UInt32 WaitForSingleObject(IntPtr hHandle, Int32 dwMilliseconds);
54 [DllImport("kernel32.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
55 public static extern bool GetExitCodeThread(IntPtr hThread, out int lpExitCode);
56
57 [DllImport("Kernel32.dll", EntryPoint = "RtlMoveMemory", SetLastError = false)]
58 public static extern void MoveMemory(object dest, IntPtr src, int size);
advapi32.dll
View Code
1 [DllImport("advapi32.dll", SetLastError = true)]
2 [return: MarshalAs(UnmanagedType.Bool)]
3 public static extern bool OpenProcessToken(IntPtr ProcessHandle, UInt32 DesiredAccess, out IntPtr TokenHandle);
4
5 [DllImport("advapi32.dll", SetLastError = true, CharSet = CharSet.Auto)]
6 [return: MarshalAs(UnmanagedType.Bool)]
7 public static extern bool LookupPrivilegeValue(string lpSystemName, string lpName, out LUID lpLuid);
8
9 // Use this signature if you want the previous state information returned
10 [DllImport("advapi32.dll", SetLastError = true)]
11 [return: MarshalAs(UnmanagedType.Bool)]
12 public static extern bool AdjustTokenPrivileges(IntPtr TokenHandle,
13 [MarshalAs(UnmanagedType.Bool)]bool DisableAllPrivileges,
14 ref TOKEN_PRIVILEGES NewState,
15 UInt32 BufferLengthInBytes,
16 ref TOKEN_PRIVILEGES PreviousState,
17 out UInt32 ReturnLengthInBytes);
第二步，创建一个辅助类，HookHelper
以下是两个公开的方法：
View Code
/// <summary>
/// 锁定一些功能键
/// </summary>
/// <param name="isLock"></param>
/// <returns></returns>
public bool Lock_SomeKey(bool isLock)
{
if (isLock)
{
if (this.m_lHookID == IntPtr.Zero)
{
IntPtr pInstance = Win32Lib.GetModuleHandle(Process.GetCurrentProcess().MainModule.ModuleName);
//安装钩子
m_lHookID = Win32Lib.SetWindowsHookEx(
(int)HookType.WH_KEYBOARD_LL,
new HookProc(LowLevelKeyboardProc),
pInstance,
0);
if (m_lHookID == IntPtr.Zero)
{
this.Lock_SomeKey(false);
return false;
}
}
return true;
}
else
{
bool result = true;
if (this.m_lHookID != IntPtr.Zero)
{
result = Win32Lib.UnhookWindowsHookEx(m_lHookID);
this.m_lHookID = IntPtr.Zero;
}
return result;
}
}
/// <summary>
/// 锁定Ctrl+Alt+Delete,Ctrl+Shift+Esc这两组系统热键
/// </summary>
/// <param name="isLock"></param>
/// <returns></returns>
public bool Lock_SysKey(bool isLock)
{
ushort iAtom = Win32Lib.GlobalFindAtom(Win32Lib.SHELL_FALG);
if (iAtom == 0)
{
long lResult = InsertAsmCode();
if (lResult > 0)
{
return false;
}
}
iAtom = Win32Lib.GlobalFindAtom(Win32Lib.ATOM_FLAG);
if (isLock)
{
//插入热键
if (iAtom == 0)
{
iAtom = Win32Lib.GlobalAddAtom(Win32Lib.ATOM_FLAG);
}
}
else
{
//删除热键
if (iAtom != 0)
{
Win32Lib.GlobalDeleteAtom(iAtom);
}
}
return true;
}
第三，提供一下源码的地址
http://ishare.iask.sina.com.cn/f/17782020.html
总结：第一次发博客，希望大家支持。
------------------------------《《《《《《《《《
2011年08月09日，程序出错的BUG修正，感谢朋友的指出。
------------------------------《《《《《《《《《
错误描述：
在多次切换锁定和解锁功能，并狂按Alt键时程序会关闭，经调试，出现如下错误：
检测到 CallbackOnCollectedDelegate
Message: 对“Demo!SomeNamespace.SomeClass+SomeDelegate::Invoke”类型的已垃圾回收委托进行了回调。这可能会导致应用程序崩溃、损坏和数据丢失。向非托管代码传递委托时，托管应用程序必须让这些委托保持活动状态，直到确信不会再次调用它们。
错误原因：
如果非托管代码需要多次调用托管代码中的回调，请将委托的引用保存为成员变量。否则会出现类似上面的异常：
。。。。
如果不用成员变量，而用局部变量引用被new出来的委托，那么非托管代码可能刚开始的几次回调是OK的，但是接下来就会出现上面所说的异常，
原因就在于GC将局部变量和局部变量引用的委托对象都销毁了，非托管代码再去访问那个函数指针时发现指针指向的地址已经无效。
解决办法：
//1.把委托拿到外面定义
private HookProc m_HookProc;
//2.在构造函数里赋值这个委托
{
m_HookProc = new HookProc(LowLevelKeyboardProc);
}
//3.在调用方法中使用这个定义过的委托。
{
//安装钩子
m_lHookID = Win32Lib.SetWindowsHookEx(
(int)HookType.WH_KEYBOARD_LL,
m_HookProc,
pInstance,
0);
//这里注释掉的是以前的代码
//m_lHookID = Win32Lib.SetWindowsHookEx(
// (int)HookType.WH_KEYBOARD_LL,
// new HookProc(LowLevelKeyboardProc),
// pInstance,
// 0);
}
再次感谢大家的支持。
