c# - 如何使用 API 调用重现 quser.exe？

Question

Quser.exe允许客户端查看远程 RDP 服务器上的用户 session 。例如，

 C:\>quser /server:MyRDPserver

 USERNAME              SESSIONNAME        ID  STATE   IDLE TIME  LOGON TIME
 userA                                     3  Disc      1+20:03  08/07/2014 12:36
 userB                                     4  Disc      1+22:28  08/07/2014 10:38

我想将此功能构建到 C++ 或 C# 程序中。是的，我可以生成 quser.exe 并解析输出，但是是否有 Win32 API 或 .Net 框架类可以提供相同的信息？具体来说:

• 用户名
• 连接状态
• 登录时间

我发现使用 WMI (Win32_LoggedOnUser) 查找相同的信息是不可靠的，因为它经常列出失效的连接。我也试过 psloggedon枚举 HKEY_USERS 的子键并寻找 Volatile Environment 键的方法，但这也有同样的问题。

Answer 1

我要回答我自己的问题。

首先，您需要确保目标机器上的权限设置正确。这需要将 HKLM\SYSTEM\CurrentControlSet\Control\Terminal Server\AllowRemoteRPC 设置为 1。执行此操作的 powershell 脚本是:

# Get the service account credential
$cred = Get-Credential my_admin_account
$Target_Computers = @("Computer_1","Computer_2")

# open the remote registry
[long]$HIVE_HKLM = 2147483650
foreach($c in $Target_Computers)
{
  $StdRegProv = Get-WmiObject -List -Namespace root\default -ComputerName $c -Credential $cred | where { $_.Name -eq "StdRegProv" }
  $StdRegProv.SetDWORDValue($HIVE_HKLM, "SYSTEM\CurrentControlSet\Control\Terminal Server", "AllowRemoteRPC", 1)
}

正如 Xearinox 所说，对于 C++，您可以使用 Win32 API 中的 WTSxxx 函数。假设您的计算机不是 XP，这里是一些 C++ 代码:

#include <string>
#include <iostream>
#include <iomanip>
#include <windows.h>
#include <WtsApi32.h>

using namespace std;

const unsigned num_connection_states = 10;
const wchar_t* connection_state_list[num_connection_states] = {
    L"Active",
    L"Connected",
    L"ConnectQuery",
    L"Shadow",
    L"Disc",
    L"Idle",
    L"Listen",
    L"Reset",
    L"Down",
    L"Init" };

int print_error(DWORD err)
{
  // format the message
  LPTSTR* ppBuffer = nullptr;
  DWORD retval = FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER, nullptr, err, 0, reinterpret_cast<LPTSTR>(ppBuffer), 0, nullptr);

  // print out
  wcerr << "Error: *ppBuffer" << endl;
  return 1;
}

wstring format_time(const LARGE_INTEGER& time)
{
  // convert to a local Win32 file time
  FILETIME ft = { time.LowPart, time.HighPart };
  FileTimeToLocalFileTime( &ft, &ft );

  // convert to a system time
  SYSTEMTIME st;
  FileTimeToSystemTime( &ft, &st );

  wchar_t local_date[255], local_time[255];
  GetDateFormat( LOCALE_USER_DEFAULT, DATE_SHORTDATE, &st, NULL, local_date, sizeof(local_date)/sizeof(wchar_t) );
  GetTimeFormat( LOCALE_USER_DEFAULT, TIME_NOSECONDS, &st, NULL, local_time, sizeof(local_time)/sizeof(wchar_t) );

  wstring result = local_date;
  result.append(L" ");
  result.append(local_time);

  return result;
}

const _int64 SECOND = 10000000;
const _int64 MINUTE = 60*SECOND;
const _int64 HOUR = 60*MINUTE;
const _int64 DAY = 24*HOUR;

wstring format_timespan(const LARGE_INTEGER& timespan)
{
  // convert to a local Win32 file time
  FILETIME ft = { timespan.LowPart, timespan.HighPart };
  FileTimeToLocalFileTime( &ft, &ft );

  // convert to a system time
  SYSTEMTIME st;
  FileTimeToSystemTime( &ft, &st );

  wchar_t local_time[255];
  int daydiff = floor(
  GetTimeFormat( LOCALE_USER_DEFAULT, TIME_NOSECONDS, &st, NULL, local_time, sizeof(local_time)/sizeof(wchar_t) );

  wstring result = local_date;
  result.append(L" ");
  result.append(local_time);

  return result;
}

int wmain(int argc, wchar_t* argv[])
{
  // check args
  if(argc > 2)
  {
    wcout << "Usage: " << argv[0] << " [server_name]\n";
    return 1;
  }

  // server name
  bool current_server = true;
  wstring server_name = L".";
  if(argc == 2)
  {
    server_name = argv[1];
    current_server = false;
  }

  // open the server
  HANDLE hServer;
  if(current_server)
    hServer = WTS_CURRENT_SERVER_HANDLE;
  else
    hServer = WTSOpenServer(const_cast<LPWSTR>(server_name.c_str()));  

  // enumerate through the sessions
  DWORD Count = 0;
  WTS_SESSION_INFO* pSessionInfo = nullptr;
  BOOL success = WTSEnumerateSessions(hServer, 0, 1, &pSessionInfo, &Count);
  if(success == 0)
    return false;

  // write the headers
  wcout << " " << left << setw(24) << "USERNAME";
  wcout << setw(19) << "SESSIONNAME";
  wcout << "ID  ";
  wcout << setw(9) << "STATE";
  wcout << "IDLE TIME  LOGON TIME";

  // loop through each session
  for(unsigned long s=0; s<Count; s++)
  {
    LPTSTR pBuffer = nullptr;
    DWORD BytesReturned = 0;
    wcout << "\n " << left;

    // try getting all info at once
    WTSINFO* info = nullptr; 
    success = WTSQuerySessionInformation(hServer, pSessionInfo[s].SessionId, WTSSessionInfo, reinterpret_cast<LPTSTR*>(&info), &BytesReturned);
    bool have_wtsinfo = true;
    if(!success)
    {
      // see why failed
      DWORD err = GetLastError();
      if(err == ERROR_NOT_SUPPORTED)
        have_wtsinfo = false;
      else
        return print_error(err);
    }

    // print user name 
    wstring user_name;
    if(have_wtsinfo)
      user_name = info->UserName;
    else
    {
      success = WTSQuerySessionInformation(hServer, pSessionInfo[s].SessionId, WTSUserName, &pBuffer, &BytesReturned);
      if(!success)
        continue;
      user_name = pBuffer;
      WTSFreeMemory(pBuffer);
    }
    wcout << setw(24) << user_name;

    // print session name 
    wstring session_name;
    if(have_wtsinfo)
      session_name = info->WinStationName;
    else
    {
      success = WTSQuerySessionInformation(hServer, pSessionInfo[s].SessionId, WTSWinStationName, &pBuffer, &BytesReturned);
      if(!success)
        continue;
      session_name = pBuffer;
      WTSFreeMemory(pBuffer);
    }
    wcout << setw(19) << session_name;

    // print session ID
    wcout << right << setw(2) << pSessionInfo[s].SessionId;

    // print connection state
    WTS_CONNECTSTATE_CLASS connect_state;
    if(have_wtsinfo)
      connect_state = info->State;
    else
    {
      success = WTSQuerySessionInformation(hServer, pSessionInfo[s].SessionId, WTSConnectState, &pBuffer, &BytesReturned);
      if(!success)
        continue;
      connect_state = *reinterpret_cast<WTS_CONNECTSTATE_CLASS*>(pBuffer);
      WTSFreeMemory(pBuffer);
    }
    if(connect_state>=num_connection_states)
      continue;
    wcout << "  " << left << setw(8) << connection_state_list[connect_state];

    // get idle time 
    LARGE_INTEGER idle = info->CurrentTime;
    idle.QuadPart -= info->LogonTime.QuadPart;

    // print logon time - not supported
    if(info->LogonTime.QuadPart!=0)
    {
      wcout << format_time(info->LogonTime);
    }

    // clean up
    WTSFreeMemory(info);
  }

  // clean up
  WTSFreeMemory(pSessionInfo);
  if(!current_server)
    WTSCloseServer(hServer);
}

对于 C#，最简单的方法是使用 Cassia library ，它基本上是围绕相同 API 函数的 C# 包装器。