1*44850Skarels /* 2*44850Skarels * Copyright (c) 1990 Regents of the University of California. 3*44850Skarels * All rights reserved. 4*44850Skarels * 5*44850Skarels * %sccs.include.redist.c% 6*44850Skarels * 7*44850Skarels * @(#)if_dl.h 7.1 (Berkeley) 07/01/90 8*44850Skarels */ 9*44850Skarels 10*44850Skarels /* 11*44850Skarels * A Link-Level Sockaddr may specify the interface in one of two 12*44850Skarels * ways: either by means of a system-provided index number (computed 13*44850Skarels * anew and possibly differently on every reboot), or by a human-readable 14*44850Skarels * string such as "il0" (for managerial convenience). 15*44850Skarels * 16*44850Skarels * Census taking actions, such as something akin to SIOCGCONF would return 17*44850Skarels * both the index and the human name. 18*44850Skarels * 19*44850Skarels * High volume transactions (such as giving a link-level ``from'' address 20*44850Skarels * in a recvfrom or recvmsg call) may be likely only to provide the indexed 21*44850Skarels * form, (which requires fewer copy operations and less space). 22*44850Skarels * 23*44850Skarels * The form and interpretation of the link-level address is purely a matter 24*44850Skarels * of convention between the device driver and its consumers; however, it is 25*44850Skarels * expected that all drivers for an interface of a given if_type will agree. 26*44850Skarels */ 27*44850Skarels 28*44850Skarels /* 29*44850Skarels * Structure of a Link-Level sockaddr: 30*44850Skarels */ 31*44850Skarels struct sockaddr_dl { 32*44850Skarels u_char sdl_len; /* Total length of sockaddr */ 33*44850Skarels u_char sdl_family; /* AF_DLI */ 34*44850Skarels u_short sdl_index; /* if != 0, system given index for interface */ 35*44850Skarels u_char sdl_type; /* interface type */ 36*44850Skarels u_char sdl_nlen; /* interface name length, no trailing 0 reqd. */ 37*44850Skarels u_char sdl_alen; /* link level address length */ 38*44850Skarels u_char sdl_slen; /* link layer selector length */ 39*44850Skarels char sdl_data[12]; /* minimum work area, can be larger; 40*44850Skarels contains both if name and ll address */ 41*44850Skarels }; 42*44850Skarels 43*44850Skarels #define LLADDR(s) ((caddr_t)((s)->sdl_data + (s)->sdl_nlen)) 44*44850Skarels 45