sys/net/if_arp.h

/*
 * Copyright (c) 1986 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 *      @(#)if_arp.h    7.3 (Berkeley) 6/27/88
 */

/*
 * Address Resolution Protocol.
 *
 * See RFC 826 for protocol description.  ARP packets are variable
 * in size; the arphdr structure defines the fixed-length portion.
 * Protocol type values are the same as those for 10 Mb/s Ethernet.
 * It is followed by the variable-sized fields ar_sha, arp_spa,
 * arp_tha and arp_tpa in that order, according to the lengths
 * specified.  Field names used correspond to RFC 826.
 */
struct  arphdr {
        u_short ar_hrd;         /* format of hardware address */
#define ARPHRD_ETHER    1       /* ethernet hardware address */
        u_short ar_pro;         /* format of protocol address */
        u_char  ar_hln;         /* length of hardware address */
        u_char  ar_pln;         /* length of protocol address */
        u_short ar_op;          /* one of: */
#define ARPOP_REQUEST   1       /* request to resolve address */
#define ARPOP_REPLY     2       /* response to previous request */
/*
 * The remaining fields are variable in size,
 * according to the sizes above.
 */
/*      u_char  ar_sha[];       /* sender hardware address */
/*      u_char  ar_spa[];       /* sender protocol address */
/*      u_char  ar_tha[];       /* target hardware address */
/*      u_char  ar_tpa[];       /* target protocol address */
};

/*
 * ARP ioctl request
 */
struct arpreq {
        struct  sockaddr arp_pa;                /* protocol address */
        struct  sockaddr arp_ha;                /* hardware address */
        int     arp_flags;                      /* flags */
};
/*  arp_flags and at_flags field values */
#define ATF_INUSE       0x01    /* entry in use */
#define ATF_COM         0x02    /* completed entry (enaddr valid) */
#define ATF_PERM        0x04    /* permanent entry */
#define ATF_PUBL        0x08    /* publish entry (respond for other host) */
#define ATF_USETRAILERS 0x10    /* has requested trailers */