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NotifyRouteChange2 (Compact 7)

  • Article

3/12/2014

This function registers to be notified for changes to IP route entries on a local device.

Syntax

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

Parameters

  • Family
    The address family on which to register for change notifications.

    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). Therefore, either constant can be used.

    The header file organization has changed, and possible values for this member are defined in the Ws2def.h header file. Note that the Ws2def.h header file is automatically included in Winsock2.h, and should never be used directly.

    The values currently supported are AF_INET, AF_INET6, and AF_UNSPEC.

    Value Meaning

    AF_INET

    Register for only IPv4 route change notifications.

    AF_INET6

    Register for only IPv6 route change notifications.

    AF_UNSPEC

    Register for both IPv4 and IPv6 route change notifications.
  • Callback
    A pointer to the function to call when a change occurs. This function will be invoked when an IP route notification is received.
  • CallerContext
    A user context passed to the callback function specified in the Callback parameter when an interface notification is received.
  • InitialNotification
    A value that indicates whether the callback should be invoked immediately after registration for change notification is complete. This initial notification does not indicate a change occurred to an IP route entry. The purpose of this parameter to provide confirmation that the callback is registered.
  • NotificationHandle
    A pointer used to return a handle that can be later used to deregister the change notification. On success, a notification handle is returned in this parameter. If an error occurs, NULL is returned.

Return Value

If the function succeeds, the return value is NO_ERROR.

If the function fails, the return value is one of the following error codes.

Error Code Meaning

ERROR_INVALID_HANDLE

An internal error occurred where an invalid handle was encountered.

ERROR_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.

ERROR_NOT_ENOUGH_MEMORY

There was insufficient memory.

Other

Use FormatMessage to obtain the message string for the returned error.

Remarks

The Family parameter must be set to either AF_INET, AF_INET6, or AF_UNSPEC.

The invocation of the callback function 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 passed to the NotifyRouteChange2 function when registering for 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 can only occur if the InitialNotification parameter that is passed to NotifyRouteChange2 was set to TRUE when registering for notifications.

IN MIB_NOTIFICATION_TYPE NotificationType

The notification type. This member can be one of the values from the MIB_NOTIFICATION_TYPE enumeration type that is defined in the Netioapi.h header file.

The callback function specified in the Callback parameter must be implemented in the same process as the application calling the NotifyRouteChange2 function. If the callback function is in a separate DLL, the DLL should be loaded before calling the NotifyRouteChange2 function to register for change notifications.

To deregister for change notifications, call the CancelMibChangeNotify2 function passing the NotificationHandle parameter returned by NotifyRouteChange2.

As soon as the NotifyRouteChange2 function is called to register for change notifications, these notifications will continue to be sent until the application deregisters for change notifications or the application terminates. If the application terminates, the system will automatically deregister any registration for change notifications. It is still recommended that an application explicitly deregister for change notifications before it terminates.

Any registration for change notifications does not persist if the system is shut down or restarted.

See Also

Reference

IP Helper Functions
CancelMibChangeNotify2
CreateIpForwardEntry2
DeleteIpForwardEntry2
GetBestRoute2
GetIpForwardEntry2
GetIpForwardTable2
InitializeIpForwardEntry
MIB_IPFORWARD_ROW2
MIB_IPFORWARD_TABLE2
MIB_NOTIFICATION_TYPE
SetIpForwardEntry2