* Copyright (c) 1986 Regents of the University of California.
* %sccs.include.redist.c%
* @(#)if_arp.h 7.6 (Berkeley) %G%
* 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.
u_short ar_hrd
; /* format of hardware address */
#define ARPHRD_ETHER 1 /* ethernet hardware format */
#define ARPHRD_FRELAY 15 /* frame relay hardware format */
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 */
#define ARPOP_REVREQUEST 3 /* request protocol address given hardware */
#define ARPOP_REVREPLY 4 /* response giving protocol address */
#define ARPOP_INVREQUEST 8 /* request to identify peer */
#define ARPOP_INVREPLY 9 /* response identifying peer */
* 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 */
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 */