base/services/w32time/w32time.c

   1 /*
   2  * PROJECT:     ReactOS Timedate Control Panel
   3  * LICENSE:     GPL-2.0+ (https://spdx.org/licenses/GPL-2.0+)
   4  * PURPOSE:     Create W32Time Service that reqularly syncs clock to Internet Time
   5  * COPYRIGHT:   Copyright 2006 Ged Murphy <gedmurphy@gmail.com>
   6  */
   7
   8 #include "w32time.h"
   9
  10 /* Get the domain name from the registry */
  11 static DWORD
  12 GetNTPServerAddress(LPWSTR *lpAddress)
  13 {
  14     HKEY hKey;
  15     WCHAR szSel[4];
  16     DWORD dwSize;
  17     LONG lRet;
  18
  19     *lpAddress = NULL;
  20     hKey = NULL;
  21
  22     lRet = RegOpenKeyExW(HKEY_LOCAL_MACHINE,
  23                          L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\DateTime\\Servers",
  24                          0,
  25                          KEY_QUERY_VALUE,
  26                          &hKey);
  27     if (lRet != ERROR_SUCCESS)
  28         goto Exit;
  29
  30     /* Get data from default value */
  31     dwSize = 4 * sizeof(WCHAR);
  32     lRet = RegQueryValueExW(hKey,
  33                             NULL,
  34                             NULL,
  35                             NULL,
  36                             (LPBYTE)szSel,
  37                             &dwSize);
  38     if (lRet != ERROR_SUCCESS)
  39         goto Exit;
  40
  41     dwSize = 0;
  42     lRet = RegQueryValueExW(hKey,
  43                             szSel,
  44                             NULL,
  45                             NULL,
  46                             NULL,
  47                             &dwSize);
  48     if (lRet != ERROR_SUCCESS)
  49         goto Exit;
  50
  51     (*lpAddress) = (LPWSTR)HeapAlloc(GetProcessHeap(),
  52                                      0,
  53                                      dwSize);
  54     if ((*lpAddress) == NULL)
  55     {
  56         lRet = ERROR_NOT_ENOUGH_MEMORY;
  57         goto Exit;
  58     }
  59
  60     lRet = RegQueryValueExW(hKey,
  61                             szSel,
  62                             NULL,
  63                             NULL,
  64                             (LPBYTE)*lpAddress,
  65                             &dwSize);
  66     if (lRet != ERROR_SUCCESS)
  67         goto Exit;
  68
  69 Exit:
  70     if (hKey)
  71         RegCloseKey(hKey);
  72     if (lRet != ERROR_SUCCESS)
  73         HeapFree(GetProcessHeap(), 0, *lpAddress);
  74
  75     return lRet;
  76 }
  77
  78
  79 /* Request the time from the current NTP server */
  80 static DWORD
  81 GetTimeFromServer(PULONG pulTime)
  82 {
  83     LPWSTR lpAddress;
  84     DWORD dwError;
  85
  86     dwError = GetNTPServerAddress(&lpAddress);
  87     if (dwError != ERROR_SUCCESS)
  88     {
  89         return dwError;
  90     }
  91
  92     *pulTime = GetServerTime(lpAddress);
  93     if (*pulTime == 0)
  94     {
  95         dwError = ERROR_GEN_FAILURE;
  96     }
  97
  98     HeapFree(GetProcessHeap(),
  99              0,
 100              lpAddress);
 101
 102     return dwError;
 103 }
 104
 105
 106 BOOL
 107 SystemSetTime(LPSYSTEMTIME lpSystemTime)
 108 {
 109     HANDLE hToken;
 110     DWORD PrevSize;
 111     TOKEN_PRIVILEGES priv, previouspriv;
 112     BOOL Ret = FALSE;
 113
 114     /*
 115      * Enable the SeSystemtimePrivilege privilege
 116      */
 117
 118     if (OpenProcessToken(GetCurrentProcess(),
 119                          TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY,
 120                          &hToken))
 121     {
 122         priv.PrivilegeCount = 1;
 123         priv.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
 124
 125         if (LookupPrivilegeValueW(NULL,
 126                                   SE_SYSTEMTIME_NAME,
 127                                   &priv.Privileges[0].Luid))
 128         {
 129             if (AdjustTokenPrivileges(hToken,
 130                                       FALSE,
 131                                       &priv,
 132                                       sizeof(previouspriv),
 133                                       &previouspriv,
 134                                       &PrevSize) &&
 135                 GetLastError() == ERROR_SUCCESS)
 136             {
 137                 /*
 138                  * We successfully enabled it, we're permitted to change the time.
 139                  */
 140                 Ret = SetSystemTime(lpSystemTime);
 141
 142                 /*
 143                  * For the sake of security, restore the previous status again
 144                  */
 145                 if (previouspriv.PrivilegeCount > 0)
 146                 {
 147                     AdjustTokenPrivileges(hToken,
 148                                           FALSE,
 149                                           &previouspriv,
 150                                           0,
 151                                           NULL,
 152                                           0);
 153                 }
 154             }
 155         }
 156         CloseHandle(hToken);
 157     }
 158
 159     return Ret;
 160 }
 161
 162
 163 /*
 164  * NTP servers state the number of seconds passed since
 165  * 1st Jan, 1900. The time returned from the server
 166  * needs adding to that date to get the current Gregorian time
 167  */
 168 static DWORD
 169 UpdateSystemTime(ULONG ulTime)
 170 {
 171     FILETIME ftNew;
 172     LARGE_INTEGER li;
 173     SYSTEMTIME stNew;
 174
 175     /* Time at 1st Jan 1900 */
 176     stNew.wYear = 1900;
 177     stNew.wMonth = 1;
 178     stNew.wDay = 1;
 179     stNew.wHour = 0;
 180     stNew.wMinute = 0;
 181     stNew.wSecond = 0;
 182     stNew.wMilliseconds = 0;
 183
 184     /* Convert to a file time */
 185     if (!SystemTimeToFileTime(&stNew, &ftNew))
 186     {
 187         return GetLastError();
 188     }
 189
 190     /* Add on the time passed since 1st Jan 1900 */
 191     li = *(LARGE_INTEGER *)&ftNew;
 192     li.QuadPart += (LONGLONG)10000000 * ulTime;
 193     ftNew = * (FILETIME *)&li;
 194
 195     /* Convert back to a system time */
 196     if (!FileTimeToSystemTime(&ftNew, &stNew))
 197     {
 198         return GetLastError();
 199     }
 200
 201     if (!SystemSetTime(&stNew))
 202     {
 203         return GetLastError();
 204     }
 205
 206     return ERROR_SUCCESS;
 207 }
 208
 209
 210 DWORD WINAPI
 211 W32TimeSyncNow(LPCWSTR cmdline,
 212                UINT blocking,
 213                UINT flags)
 214 {
 215     DWORD dwError;
 216     ULONG ulTime;
 217
 218     dwError = GetTimeFromServer(&ulTime);
 219     if (dwError != ERROR_SUCCESS)
 220     {
 221         return dwError;
 222     }
 223
 224     if (ulTime != 0)
 225     {
 226         dwError = UpdateSystemTime(ulTime);
 227     }
 228
 229     return dwError;
 230 }
 231