Inside Macintosh: Open Transport /

Chapter 8 - TCP/IP Services / TCP/IP Services Reference

Constants and Data Types

Internet Interface Information Structure

The OTInetGetInterfaceInfo function (page 8-50) returns information about the local host in an internet interface information structure. The internet interface information structure is defined by the InetInterfaceInfo data type.

struct InetInterfaceInfo {
   InetHost       fAddress;         /* host address */
   InetHost       fNetmask;         /* subnet mask */
   InetHost       fBroadcastAddr;   /* broadcast address */
   InetHost       fDefaultGatewayAddr;/* default gateway 
                                        address */
   InetHost       fDNSAddr          /* DNS address*/
   UInt16         fVersion;         /* version number */
   UInt16         fHWAddrLen        /* HW addr length */
   UInt8*         fHWAddr;          /* HW address */
   UInt32         fIfMTU            /* Max Trans Unit */
   UInt8*         fReservedPtrs[2]; /* reserved */
   InetDomainName fDomainName;      /* host's domain name */
   UInt8          fReserved[256];   /* reserved */
};

Field Description

fAddress

The IP address of the local host in network byte order (that is, high-order byte first) in hexadecimal notation.

fNetMask

The subnet mask of the local IP network.

fBroadcastAddr

The broadcast address for the interface. The broadcast address can also be calculated by performing an OR operation on the address with the complement of the subnet mask.

fDefaultGatewayAddr

The IP address of the default gateway. The default gateway is a router or gateway that can forward any packet destined outside the locally connected subnet. This information is optional; if you don't have a default gateway, you need a specific route for every packet or message sent to a subnet other than your own your directly connected subnet.

fDNSAddr

The address of a domain name server. This value can be returned by a server or typed in by the user during configuration of the TCP/IP interface.

fVersion

The version of the OTInetGetInterfaceInfo function; currently equal to 1.

fHWAddrLen

The length (in bytes) of the hardware address.

fHWAddr

A pointer to the hardware address.

fIfMTU

The maximum transmission unit size permitted for this interface's hardware.

fReservedPtrs

Reserved.

fDomainName

The default domain name of the host. This name doesn't include the host name.

fReserved

Reserved.