vncservice.cpp

realvnc是一个非常流行的远程控制程序

//  Copyright (C) 2002-2003 RealVNC Ltd. All Rights Reserved.
//  Copyright (C) 1999 AT&T Laboratories Cambridge. All Rights Reserved.
//
//  This file is part of the VNC system.
//
//  The VNC system is free software; you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation; either version 2 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program; if not, write to the Free Software
//  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
//  USA.
//
// If the source code for the VNC system is not available from the place 
// whence you received this file, check http://www.uk.research.att.com/vnc or contact
// the authors on [e-mail] for information on obtaining it.


// vncService

// Implementation of service-oriented functionality of WinVNC

#include "stdhdrs.h"

// Header

#include "vncService.h"

#include <lmcons.h>
#include "omnithread.h"
#include "WinVNC.h"
#include "vncMenu.h"
#include "vncTimedMsgBox.h"

// Error message logging
void LogErrorMsg(char *message);

// OS-SPECIFIC ROUTINES

// Create an instance of the vncService class to cause the static fields to be
// initialised properly

vncService init;

DWORD	g_platform_id;
BOOL	g_impersonating_user = 0;
DWORD	g_version_major;
DWORD	g_version_minor;

vncService::vncService()
{
    OSVERSIONINFO osversioninfo;
    osversioninfo.dwOSVersionInfoSize = sizeof(osversioninfo);

    // Get the current OS version
    if (!GetVersionEx(&osversioninfo))
	    g_platform_id = 0;
    g_platform_id = osversioninfo.dwPlatformId;
	g_version_major = osversioninfo.dwMajorVersion;
	g_version_minor = osversioninfo.dwMinorVersion;
}

// CurrentUser - fills a buffer with the name of the current user!
BOOL
GetCurrentUser(char *buffer, UINT size)
{
	// How to obtain the name of the current user depends upon the OS being used
	if ((g_platform_id == VER_PLATFORM_WIN32_NT) && vncService::RunningAsService())
	{
		// Windows NT, service-mode

		// -=- FIRSTLY - verify that a user is logged on

		// Get the current Window station
		HWINSTA station = GetProcessWindowStation();
		if (station == NULL)
			return FALSE;

		// Get the current user SID size
		DWORD usersize;
		GetUserObjectInformation(station,
			UOI_USER_SID, NULL, 0, &usersize);

		// Check the required buffer size isn't zero
		if (usersize == 0)
		{
			// No user is logged in - ensure we're not impersonating anyone
			RevertToSelf();
			g_impersonating_user = FALSE;

			// Return "" as the name...
			if (strlen("") >= size)
				return FALSE;
			strcpy(buffer, "");

			return TRUE;
		}

		// -=- SECONDLY - a user is logged on but if we're not impersonating
		//     them then we can't continue!
		if (!g_impersonating_user) {
			// Return "" as the name...
			if (strlen("") >= size)
				return FALSE;
			strcpy(buffer, "");
			return TRUE;
		}
	}
		
	// -=- When we reach here, we're either running under Win9x, or we're running
	//     under NT as an application or as a service impersonating a user
	// Either way, we should find a suitable user name.

	switch (g_platform_id)
	{

	case VER_PLATFORM_WIN32_WINDOWS:
	case VER_PLATFORM_WIN32_NT:
		{
			// Just call GetCurrentUser
			DWORD length = size;

			if (GetUserName(buffer, &length) == 0)
			{
				UINT error = GetLastError();

				if (error == ERROR_NOT_LOGGED_ON)
				{
					// No user logged on
					if (strlen("") >= size)
						return FALSE;
					strcpy(buffer, "");
					return TRUE;
				}
				else
				{
					// Genuine error...
					vnclog.Print(LL_INTERR, VNCLOG("getusername error %d\n"), GetLastError());
					return FALSE;
				}
			}
		}
		return TRUE;
	};

	// OS was not recognised!
	return FALSE;
}

BOOL
vncService::CurrentUser(char *buffer, UINT size)
{
  BOOL result = GetCurrentUser(buffer, size);
  if (result && (strcmp(buffer, "") == 0) && !vncService::RunningAsService()) {
    strncpy(buffer, "Default", size);
  }
  return result;
}

// IsWin95 - returns a BOOL indicating whether the current OS is Win95
BOOL
vncService::IsWin95()
{
	return (g_platform_id == VER_PLATFORM_WIN32_WINDOWS);
}

// IsWinNT - returns a bool indicating whether the current OS is WinNT
BOOL
vncService::IsWinNT()
{
	return (g_platform_id == VER_PLATFORM_WIN32_NT);
}

// Version info
DWORD
vncService::VersionMajor()
{
	return g_version_major;
}

DWORD
vncService::VersionMinor()
{
	return g_version_minor;
}

// Internal routine to find the WinVNC menu class window and
// post a message to it!

BOOL
PostToWinVNC(UINT message, WPARAM wParam, LPARAM lParam)
{
	// Locate the hidden WinVNC menu window
	HWND hservwnd = FindWindow(MENU_CLASS_NAME, NULL);
	if (hservwnd == NULL)
		return FALSE;

	// Post the message to WinVNC
	PostMessage(hservwnd, message, wParam, lParam);
	return TRUE;
}

// Static routines only used on Windows NT to ensure we're in the right desktop
// These routines are generally available to any thread at any time.

// - SelectDesktop(HDESK)
// Switches the current thread into a different desktop by deskto handle
// This call takes care of all the evil memory management involved

BOOL
vncService::SelectHDESK(HDESK new_desktop)
{
	// Are we running on NT?
	if (IsWinNT())
	{
		HDESK old_desktop = GetThreadDesktop(GetCurrentThreadId());

		DWORD dummy;
		char new_name[256];

		if (!GetUserObjectInformation(new_desktop, UOI_NAME, &new_name, 256, &dummy)) {
			return FALSE;
		}

		vnclog.Print(LL_INTERR, VNCLOG("SelectHDESK to %s (%x) from %x\n"), new_name, new_desktop, old_desktop);

		// Switch the desktop
		if(!SetThreadDesktop(new_desktop)) {
      vnclog.Print(LL_INTERR, VNCLOG("unable to SetThreadDesktop\n"), GetLastError());
			return FALSE;
		}

		// Switched successfully - destroy the old desktop
		if (!CloseDesktop(old_desktop))
			vnclog.Print(LL_INTERR, VNCLOG("SelectHDESK failed to close old desktop %x (Err=%d)\n"), old_desktop, GetLastError());

		return TRUE;
	}

	return TRUE;
}

// - SelectDesktop(char *)
// Switches the current thread into a different desktop, by name
// Calling with a valid desktop name will place the thread in that desktop.
// Calling with a NULL name will place the thread in the current input desktop.

BOOL
vncService::SelectDesktop(char *name)
{
	// Are we running on NT?
	if (IsWinNT())
	{
		HDESK desktop;

		if (name != NULL)
		{
			// Attempt to open the named desktop
			desktop = OpenDesktop(name, 0, FALSE,
				DESKTOP_CREATEMENU | DESKTOP_CREATEWINDOW |
				DESKTOP_ENUMERATE | DESKTOP_HOOKCONTROL |
				DESKTOP_WRITEOBJECTS | DESKTOP_READOBJECTS |
				DESKTOP_SWITCHDESKTOP | GENERIC_WRITE);
		}
		else
		{
			// No, so open the input desktop
			desktop = OpenInputDesktop(0, FALSE,
				DESKTOP_CREATEMENU | DESKTOP_CREATEWINDOW |
				DESKTOP_ENUMERATE | DESKTOP_HOOKCONTROL |
				DESKTOP_WRITEOBJECTS | DESKTOP_READOBJECTS |
				DESKTOP_SWITCHDESKTOP | GENERIC_WRITE);
		}

		// Did we succeed?
		if (desktop == NULL) {
      vnclog.Print(LL_INTERR, VNCLOG("unable to open desktop:%d\n"), GetLastError());
			return FALSE;
		}

		// Switch to the new desktop
		if (!SelectHDESK(desktop)) {
			// Failed to enter the new desktop, so free it!
			if (!CloseDesktop(desktop))
				vnclog.Print(LL_INTERR, VNCLOG("SelectDesktop failed to close desktop:%d\n"), GetLastError());
			return FALSE;
		}

		// We successfully switched desktops!
		return TRUE;
	}

	return (name == NULL);
}

// Find the visible window station and switch to it
// This would allow the service to be started non-interactive
// Needs more supporting code & a redesign of the server core to
// work, with better partitioning between server & UI components.

static HWINSTA home_window_station = GetProcessWindowStation();

BOOL CALLBACK WinStationEnumProc(LPTSTR name, LPARAM param) {
	HWINSTA station = OpenWindowStation(name, FALSE, GENERIC_ALL);
	HWINSTA oldstation = GetProcessWindowStation();
	USEROBJECTFLAGS flags;
	if (!GetUserObjectInformation(station, UOI_FLAGS, &flags, sizeof(flags), NULL)) {
		return TRUE;
	}
	BOOL visible = flags.dwFlags & WSF_VISIBLE;
	if (visible) {
		if (SetProcessWindowStation(station)) {
			if (oldstation != home_window_station) {
				CloseWindowStation(oldstation);
			}
		} else {
			CloseWindowStation(station);
		}
		return FALSE;
	}
	return TRUE;
}

BOOL
vncService::SelectInputWinStation()
{
	home_window_station = GetProcessWindowStation();
	return EnumWindowStations(&WinStationEnumProc, NULL);
}

void
vncService::SelectHomeWinStation()
{
	HWINSTA station=GetProcessWindowStation();
	SetProcessWindowStation(home_window_station);
	CloseWindowStation(station);
}

// NT only function to establish whether we're on the current input desktop

BOOL
vncService::InputDesktopSelected()
{
	// Are we running on NT?
	if (IsWinNT())
	{
		// Get the input and thread desktops
		HDESK threaddesktop = GetThreadDesktop(GetCurrentThreadId());
		HDESK inputdesktop = OpenInputDesktop(0, FALSE,
				DESKTOP_CREATEMENU | DESKTOP_CREATEWINDOW |
				DESKTOP_ENUMERATE | DESKTOP_HOOKCONTROL |
				DESKTOP_WRITEOBJECTS | DESKTOP_READOBJECTS |
				DESKTOP_SWITCHDESKTOP | GENERIC_WRITE);

		// Get the desktop names:
		// *** I think this is horribly inefficient but I'm not sure.
		if (inputdesktop == NULL)
		    return FALSE;

		DWORD dummy;
		char threadname[256];
		char inputname[256];

		if (!GetUserObjectInformation(threaddesktop, UOI_NAME, &threadname, 256, &dummy)) {
			if (!CloseDesktop(inputdesktop))
				vnclog.Print(LL_INTWARN, VNCLOG("failed to close input desktop\n"));
			return FALSE;
		}
		_ASSERT(dummy <= 256);
		if (!GetUserObjectInformation(inputdesktop, UOI_NAME, &inputname, 256, &dummy)) {
			if (!CloseDesktop(inputdesktop))
				vnclog.Print(LL_INTWARN, VNCLOG("failed to close input desktop\n"));
			return FALSE;
		}
		_ASSERT(dummy <= 256);

		if (!CloseDesktop(inputdesktop))
			vnclog.Print(LL_INTWARN, VNCLOG("failed to close input desktop\n"));

		if (strcmp(threadname, inputname) != 0)
			return FALSE;
	}

	return TRUE;
}

// Static routine used to fool Winlogon into thinking CtrlAltDel was pressed

void *
SimulateCtrlAltDelThreadFn(void *context)
{
	HDESK old_desktop = GetThreadDesktop(GetCurrentThreadId());

	// Switch into the Winlogon desktop
	if (!vncService::SelectDesktop("Winlogon"))
	{
		vnclog.Print(LL_INTERR, VNCLOG("failed to select logon desktop\n"));
		return FALSE;
	}

	vnclog.Print(LL_ALL, VNCLOG("generating ctrl-alt-del\n"));

	// Fake a hotkey event to any windows we find there.... :(
	// Winlogon uses hotkeys to trap Ctrl-Alt-Del...
	PostMessage(HWND_BROADCAST, WM_HOTKEY, 0, MAKELONG(MOD_ALT | MOD_CONTROL, VK_DELETE));

	// Switch back to our original desktop
	if (old_desktop != NULL)
		vncService::SelectHDESK(old_desktop);

	return NULL;
}