[WINLOGON] Close all the user network connections only at logoff (#8324)

Per-user network connections (to shared drives...) are restored at user
logon: `HandleLogon() -> RestoreAllConnections()`.
These connections should be closed only at user logoff, in `HandleLogoff()`,
instead of inside the common logoff/shutdown thread, which is also invoked
at... shutdown!

- Isolate the network connections closing inside a `CloseAllConnections()`
  helper (which also performs the necessary user thread impersonation).

- Invoke this helper directly inside `HandleLogoff()`, and also re-enable
  the `IDS_CLOSINGNETWORKCONNECTIONS` message display.

base/system/winlogon/sas.c

@@ -429,7 +429,8 @@ PlayEventSound(
 
 static
 VOID
-RestoreAllConnections(PWLSESSION Session)
+RestoreAllConnections(
+    _In_ PWLSESSION Session)
 {
     DWORD dRet;
     HANDLE hEnum;
@@ -441,9 +442,7 @@ RestoreAllConnections(PWLSESSION Session)
 
     UserProfile = (Session && Session->UserToken);
     if (!UserProfile)
-    {
         return;
-    }
 
     if (!ImpersonateLoggedOnUser(Session->UserToken))
     {
@@ -471,7 +470,7 @@ RestoreAllConnections(PWLSESSION Session)
         dSize = 0x1000;
         dCount = -1;
 
-        memset(lpRes, 0, dSize);
+        ZeroMemory(lpRes, dSize);
         dRet = WNetEnumResource(hEnum, &dCount, lpRes, &dSize);
         if (dRet == WN_SUCCESS || dRet == WN_MORE_DATA)
         {
@@ -491,6 +490,17 @@ quit:
     RevertToSelf();
 }
 
+static
+VOID
+CloseAllConnections(
+    _In_ PWLSESSION Session)
+{
+    if (!Session->UserToken || !ImpersonateLoggedOnUser(Session->UserToken))
+        return;
+    WNetClearConnections(NULL);
+    RevertToSelf();
+}
+
 /**
  * @brief
  * Frees the Profile information structure (WLX_PROFILE_V1_0
@@ -757,9 +767,6 @@ LogoffShutdownThread(
         ret = FALSE;
     }
 
-    /* Cancel all the user connections */
-    WNetClearConnections(NULL);
-
     if (UserToken)
         RevertToSelf();
 
@@ -1036,15 +1043,18 @@ HandleLogoff(
 
     PlayLogoffShutdownSound(Session, WLX_SHUTTINGDOWN(wlxAction));
 
+    /* Close all user network connections */
+    DisplayStatusMessage(Session, Session->WinlogonDesktop, IDS_CLOSINGNETWORKCONNECTIONS);
+    CloseAllConnections(Session);
+    // TODO: Do any other user-specific network-related cleaning:
+    // user-added NetAPI message aliases; user cached credentials (remote login)...
+
     SetWindowStationUser(Session->InteractiveWindowStation,
                          &LuidNone, NULL, 0);
 
     // DisplayStatusMessage(Session, Session->WinlogonDesktop, IDS_LOGGINGOFF);
     CallNotificationDlls(Session, LogoffHandler);
 
-    // FIXME: Closing network connections!
-    // DisplayStatusMessage(Session, Session->WinlogonDesktop, IDS_CLOSINGNETWORKCONNECTIONS);
-
     /* Kill remaining COM processes that may have been started by logoff scripts */
     hThread = CreateThread(psa, 0, KillComProcesses, (PVOID)Session->UserToken, 0, NULL);
     if (hThread)