NotifyRouteChange2 function

Article
03/03/2023

The NotifyRouteChange2 function registers the driver to be notified for changes to IP route entries on a local computer.

Syntax

NETIOAPI_API NotifyRouteChange2(
  _In_    ADDRESS_FAMILY             Family,
  _In_    PIPFORWARD_CHANGE_CALLBACK Callback,
  _In_    PVOID                      CallerContext,
  _In_    BOOLEAN                    InitialNotification,
  _Inout_ HANDLE                     *NotificationHandle
);

Parameters

Family [in]
The address family to register the driver for change notifications on.

Possible values for the address family are listed in the Winsock2.h header file. Note that the values for the AF_ address family and PF_ protocol family constants are identical (for example, AF_INET and PF_INET), so you can use either constant.

On Windows Vista and later versions of the Windows operating systems, possible values for the Family parameter are defined in the Ws2def.h header file. Note that the Ws2def.h header file is automatically included in Netioapi.h and you should never use Ws2def.h directly.

The following values are currently supported for the address family:
- AF_INET
  The IPv4 address family. When this value is specified, this function registers the driver only for IPv4 route change notifications.
- AF_INET6
  The IPv6 address family. When this value is specified, this function registers the driver only for IPv6 route change notifications.
- AF_UNSPEC
  The address family is unspecified. When this value is specified, this function registers the driver for both IPv4 and IPv6 route change notifications.
Callback [in]
A pointer to the function to call when a change occurs. This function is called when an interface notification is received.
CallerContext [in]
A user context that is passed to the callback function that is specified in the Callback parameter when an interface notification is received.
InitialNotification [in]
A value that indicates whether the callback should be invoked immediately after registration for change notification completes. This initial notification does not indicate a change occurred to the IP route. The purpose of this parameter to provide confirmation that the callback is registered.
NotificationHandle [in, out]
A pointer to a MIB_IPINTERFACE_ROW structure to initialize. On successful return, the members in this structure are initialized with default information for an interface on the local computer.

Return value

NotifyRouteChange2 returns STATUS_SUCCESS if the function succeeds.

If the function fails, NotifyRouteChange2 returns one of the following error codes.

Return code	Description
ERROR_INVALID_HANDLE	An internal error occurred where an invalid handle was encountered.
STATUS_INVALID_PARAMETER	An invalid parameter was passed to the function. This error is returned if the Family parameter was not either AF_INET, AF_INET6, or AF_UNSPEC.
STATUS_NOT_ENOUGH_MEMORY	There was insufficient memory.
Other	Use the FormatMessage function to obtain the message string for the returned error.

Remarks

Your driver must set the Family parameter to either AF_INET, AF_INET6, or AF_UNSPEC.

The invocation of the callback function that is specified in the Callback parameter is serialized. The callback function should be defined as a function of type VOID. The parameters that are passed to the callback function include the following.

Parameter	Description
IN PVOID CallerContext	The CallerContext parameter that is passed to the NotifyRouteChange2 function when it is registering the driver for change notifications.
IN PMIB_IPFORWARD_ROW2 Row OPTIONAL	A pointer to the MIB_IPFORWARD_ROW2 entry for the IP route entry that was changed. This parameter is a NULL pointer when the MIB_NOTIFICATION_TYPE value that is passed in the NotificationType parameter to the callback function is set to MibInitialNotification. This situation can occur only if the InitialNotification parameter that is passed to NotifyRouteChange2 was set to TRUE when registering the driver for change notifications.
IN MIB_NOTIFICATION_TYPE NotificationType	The notification type. This member can be one of the values from the MIB_NOTIFICATION_TYPE enumeration type.

To deregister the driver for change notifications, call the CancelMibChangeNotify2 function, passing the NotificationHandle parameter that NotifyRouteChange2 returns.

Requirements

Target platform	Universal
Version	Available in Windows Vista and later versions of the Windows operating systems.
Header	Netioapi.h (include Netioapi.h)
Library	Netio.lib
IRQL	< DISPATCH_LEVEL