GetIpForwardEntry2 function

Article
03/03/2023

The GetIpForwardEntry2 function retrieves information for an IP route entry on a local computer.

Syntax

NETIOAPI_API GetIpForwardEntry2(
  _Inout_ PMIB_IPFORWARD_ROW2 Row
);

Parameters

Row [in, out]
A pointer to a MIB_IPFORWARD_ROW2 structure entry for an IP route entry. On successful return, this structure is updated with the properties for the IP route entry.

Return value

GetIpForwardEntry2 returns STATUS_SUCCESS if the function succeeds.

If the function fails, GetIpForwardEntry2 returns one of the following error codes:

Return code	Description
STATUS_INVALID_PARAMETER	An invalid parameter was passed to the function. This error is returned if one of the following situations occurs: A NULL pointer is passed in the Row parameter. The DestinationPrefix member of the MIB_IPFORWARD_ROW2 structure that the Row parameter points to was not specified. The NextHop member of the MIB_IPFORWARD_ROW2 structure was not specified. Both InterfaceLuid and InterfaceIndex members of the MIB_IPFORWARD_ROW2 structure were unspecified. The PreferredLifetime member of the MIB_IPFORWARD_ROW2 structure is greater than the ValidLifetime member. The SitePrefixLength member of the MIB_IPFORWARD_ROW2 structure is greater than the prefix length that is specified by the DestinationPrefix member.
STATUS_NOT_FOUND	The specified interface could not be found. This error is returned if the function cannot find the network interface that is specified by the InterfaceLuid or InterfaceIndex member of the MIB_IPFORWARD_ROW2 structure that the Row parameter points to.
STATUS_NOT_SUPPORTED	The request is not supported. This error is returned if no IPv4 stack is located on the local computer and AF_INET was specified in the address family in the DestinationPrefix member of the MIB_IPFORWARD_ROW2 structure that the Row parameter points to, or if no IPv6 stack is located on the local computer and AF_INET6 was specified for the address family in the DestinationPrefix member.
Other	Use the FormatMessage function to obtain the message string for the returned error.

Remarks

The GetIpForwardEntry2 function is used to retrieve a MIB_IPFORWARD_ROW2 structure entry.

On input, your driver must initialize the following members of the MIB_IPFORWARD_ROW2 structure that the Row parameter points to.

DestinationPrefix
Set to a valid IPv4 or IPv6 address prefix and family.
NextHop
Set to a valid IPv4 or IPv6 address and family.
InterfaceLuid or InterfaceIndex
These members are used in the order that is listed earlier. So if InterfaceLuid is specified, this member is used to determine the interface. If no value was set for the InterfaceLuid member (the value of this member was set to zero), the InterfaceIndex member is next used to determine the interface.

On output, when the call is successful, GetIpForwardEntry2 retrieves the other properties for the IP route entry and fills out the MIB_IPFORWARD_ROW2 structure that the Row parameter points to.

The route metric offset that is specified in the Metric member of the MIB_IPFORWARD_ROW2 structure that the Row parameter points to represents only part of the complete route metric. The complete metric is a combination of this route metric added to the interface metric that is specified in the Metric member of the MIB_IPINTERFACE_ROW structure of the associated interface. A driver can retrieve the interface metric by calling the GetIpInterfaceEntry function.

Your driver can call the GetIpForwardTable2 function to enumerate the IP route entries on a local computer.

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