GetIpForwardEntry2 function (netioapi.h)

Article
10/13/2021

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

Syntax

IPHLPAPI_DLL_LINKAGE _NETIOAPI_SUCCESS_ NETIOAPI_API GetIpForwardEntry2(
  [in, out] PMIB_IPFORWARD_ROW2 Row
);

Parameters

[in, out] Row

A pointer to a MIB_IPFORWARD_ROW2 structure entry for an IP route entry. On successful return, this structure will be updated with the properties for the IP route entry.

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.

Return code	Description
ERROR_INVALID_PARAMETER	An invalid parameter was passed to the function. This error is returned if a NULL pointer is passed in the Row parameter, the DestinationPrefix member of the MIB_IPFORWARD_ROW2 pointed to by the Row parameter was not specified, the NextHop member of the MIB_IPFORWARD_ROW2 pointed to by the Row parameter was not specified, or both the InterfaceLuid or InterfaceIndex members of the MIB_IPFORWARD_ROW2 pointed to by the Row parameter were unspecified.
ERROR_NOT_FOUND	Element not found. This error is returned if the network interface specified by the InterfaceLuid or InterfaceIndex member of the MIB_IPFORWARD_ROW2 structure pointed to by the Row parameter does not match the IP address prefix and address family specified in the DestinationPrefix member in the MIB_IPFORWARD_ROW2 structure.
ERROR_NOT_SUPPORTED	The request is not supported. This error is returned if no IPv4 stack is on the local computer and AF_INET was specified in the address family in the DestinationPrefix member of the MIB_IPFORWARD_ROW2 pointed to by the Row parameter. This error is also returned if no IPv6 stack is on the local computer and AF_INET6 was specified for the address family in the DestinationPrefix member.
Other	Use FormatMessage to obtain the message string for the returned error.

Remarks

The GetIpForwardEntry2 function is defined on Windows Vista and later.

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

On input, the DestinationPrefix member in the MIB_IPFORWARD_ROW2 structure pointed to by the Row parameter must be initialized to a valid IPv4 or IPv6 address prefix and family. On input, the NextHop member in the MIB_IPFORWARD_ROW2 structure pointed to by the Row parameter must be initialized to a valid IPv4 or IPv6 address and family. In addition, at least one of the following members in the MIB_IPFORWARD_ROW2 structure pointed to the Row parameter must be initialized: the InterfaceLuid or InterfaceIndex.

The fields are used in the order listed above. So if the InterfaceLuid is specified, then this member is used to determine the interface. If no value was set for the InterfaceLuid member (the values of this member was set to zero), then 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 pointed to by the Row parameter.

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

The GetIpForwardTable2 function can be called to enumerate the IP route entries on a local computer.

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps only]
Minimum supported server	Windows Server 2008 [desktop apps only]
Target Platform	Windows
Header	netioapi.h (include Iphlpapi.h)
Library	Iphlpapi.lib
DLL	Iphlpapi.dll