/*      $OpenBSD: if_dl.h,v 1.13 2023/11/12 17:51:40 bluhm Exp $        */
/*      $NetBSD: if_dl.h,v 1.8 1995/03/26 20:30:13 jtc Exp $    */

/*
 * Copyright (c) 1990, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)if_dl.h     8.1 (Berkeley) 6/10/93
 */

/*
 * A Link-Level Sockaddr may specify the interface in one of two
 * ways: either by means of a system-provided index number (computed
 * anew and possibly differently on every reboot), or by a human-readable
 * string such as "il0" (for managerial convenience).
 *
 * Census taking actions, such as something akin to SIOCGCONF would return
 * both the index and the human name.
 *
 * High volume transactions (such as giving a link-level ``from'' address
 * in a recvfrom or recvmsg call) may be likely only to provide the indexed
 * form, (which requires fewer copy operations and less space).
 *
 * The form and interpretation  of the link-level address is purely a matter
 * of convention between the device driver and its consumers; however, it is
 * expected that all drivers for an interface of a given if_type will agree.
 */

#ifndef _NET_IF_DL_H_
#define _NET_IF_DL_H_

/*
 * Structure of a Link-Level sockaddr:
 */
struct sockaddr_dl {
        u_char    sdl_len;      /* Total length of sockaddr */
        u_char    sdl_family;   /* AF_LINK */
        u_int16_t sdl_index;    /* if != 0, system given index for interface */
        u_char    sdl_type;     /* interface type */
        u_char    sdl_nlen;     /* interface name length, no trailing 0 reqd. */
        u_char    sdl_alen;     /* link level address length */
        u_char    sdl_slen;     /* link layer selector length, mostly 0 */
        char      sdl_data[24]; /* minimum work area, can be larger;
                                   contains both if name and ll address;
                                   big enough for IFNAMSIZ plus 8byte ll addr */
};

#define LLADDR(s) ((caddr_t)((s)->sdl_data + (s)->sdl_nlen))

#ifdef _KERNEL

static inline struct sockaddr_dl *
satosdl(struct sockaddr *sa)
{
        return ((struct sockaddr_dl *)(sa));
}

static inline const struct sockaddr_dl *
satosdl_const(const struct sockaddr *sa)
{
        return ((const struct sockaddr_dl *)(sa));
}

static inline struct sockaddr *
sdltosa(struct sockaddr_dl *sdl)
{
        return ((struct sockaddr *)(sdl));
}

#else /* _KERNEL */

__BEGIN_DECLS
char    *link_ntoa(const struct sockaddr_dl *);
__END_DECLS

#endif /* _KERNEL */
#endif /* _NET_IF_DL_H_ */