1 /* 2 * Copyright (c) 1990, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)if_dl.h 8.1 (Berkeley) 06/10/93 8 */ 9 10 /* 11 * A Link-Level Sockaddr may specify the interface in one of two 12 * ways: either by means of a system-provided index number (computed 13 * anew and possibly differently on every reboot), or by a human-readable 14 * string such as "il0" (for managerial convenience). 15 * 16 * Census taking actions, such as something akin to SIOCGCONF would return 17 * both the index and the human name. 18 * 19 * High volume transactions (such as giving a link-level ``from'' address 20 * in a recvfrom or recvmsg call) may be likely only to provide the indexed 21 * form, (which requires fewer copy operations and less space). 22 * 23 * The form and interpretation of the link-level address is purely a matter 24 * of convention between the device driver and its consumers; however, it is 25 * expected that all drivers for an interface of a given if_type will agree. 26 */ 27 28 /* 29 * Structure of a Link-Level sockaddr: 30 */ 31 struct sockaddr_dl { 32 u_char sdl_len; /* Total length of sockaddr */ 33 u_char sdl_family; /* AF_DLI */ 34 u_short sdl_index; /* if != 0, system given index for interface */ 35 u_char sdl_type; /* interface type */ 36 u_char sdl_nlen; /* interface name length, no trailing 0 reqd. */ 37 u_char sdl_alen; /* link level address length */ 38 u_char sdl_slen; /* link layer selector length */ 39 char sdl_data[12]; /* minimum work area, can be larger; 40 contains both if name and ll address */ 41 }; 42 43 #define LLADDR(s) ((caddr_t)((s)->sdl_data + (s)->sdl_nlen)) 44 45 #ifndef KERNEL 46 47 #include <sys/cdefs.h> 48 49 __BEGIN_DECLS 50 void link_addr __P((const char *, struct sockaddr_dl *)); 51 char *link_ntoa __P((const struct sockaddr_dl *)); 52 __END_DECLS 53 54 #endif /* !KERNEL */ 55