GetBestRoute2 function (netioapi.h)

The GetBestRoute2 function retrieves the IP route entry on the local computer for the best route to the specified destination IP address.

Syntax

IPHLPAPI_DLL_LINKAGE _NETIOAPI_SUCCESS_ NETIOAPI_API GetBestRoute2(
  NET_LUID            *InterfaceLuid,
  NET_IFINDEX         InterfaceIndex,
  const SOCKADDR_INET *SourceAddress,
  const SOCKADDR_INET *DestinationAddress,
  ULONG               AddressSortOptions,
  PMIB_IPFORWARD_ROW2 BestRoute,
  SOCKADDR_INET       *BestSourceAddress
);

Parameters

InterfaceLuid

The locally unique identifier (LUID) to specify the network interface associated with an IP route entry.

InterfaceIndex

The local index value to specify the network interface associated with an IP route entry. This index value may change when a network adapter is disabled and then enabled, or under other circumstances, and should not be considered persistent.

SourceAddress

The source IP address. This parameter may be omitted and passed as a NULL pointer.

DestinationAddress

The destination IP address.

AddressSortOptions

A set of options that affect how IP addresses are sorted. This parameter is not currently used.

BestRoute

A pointer to the MIB_IPFORWARD_ROW2 for the best route from the source IP address to the destination IP address.

BestSourceAddress

A pointer to the best source IP address.

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 DestinationAddress, BestSourceAddress, or the BestRoute parameter. This error is also returned if the DestinationAddress parameter does not specify an IPv4 or IPv6 address and family.
ERROR_FILE_NOT_FOUND
The specified interface could not be found. This error is returned if the network interface specified by the InterfaceLuid or InterfaceIndex parameter could not be found.
ERROR_NOT_SUPPORTED
The request is not supported. This error is returned if no IPv4 stack is on the local computer and an IPv4 address and family was specified in the DestinationAddress parameter. This error is also returned if no IPv6 stack is on the local computer and an IPv6 address and family was specified in the DestinationAddress parameter.
Other
Use FormatMessage to obtain the message string for the returned error.

Remarks

The GetBestRoute2 function is defined on Windows Vista and later.

The GetBestRoute2 function is used to retrieve a MIB_IPFORWARD_ROW2 structure entry for the best route from a source IP address to a destination IP address.

On input, the DestinationAddress parameter must be initialized to a valid IPv4 or IPv6 address and family. On input, the SourceAddress parameter may be initialized to the preferred IPv4 or IPv6 address and family. In addition, at least one of the following parameters must be initialized: the InterfaceLuid or InterfaceIndex.

The parameters 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, GetBestRoute2 retrieves and MIB_IPFORWARD_ROW2 structure for the best route from the source IP address the destination IP address.

Requirements

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

See also

CreateIpForwardEntry2

DeleteIpForwardEntry2

GetIpForwardEntry2

GetIpForwardTable2

InitializeIpForwardEntry

MIB_IPFORWARD_ROW2

MIB_IPFORWARD_TABLE2

NotifyRouteChange2

SetIpForwardEntry2