1 /* 2 * Copyright (c) 1986 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 * 6 * @(#)if_arp.h 6.1 (Berkeley) 01/24/86 7 */ 8 9 /* 10 * Address Resolution Protocol. 11 * 12 * See RFC 826 for protocol description. ARP packets are variable 13 * in size; the arphdr structure defines the fixed-length portion. 14 * Protocol type values are the same as those for 10 Mb/s Ethernet. 15 * It is followed by the variable-sized fields ar_sha, arp_spa, 16 * arp_tha and arp_tpa in that order, according to the lengths 17 * specified. Field names used correspond to RFC 826. 18 */ 19 struct arphdr { 20 u_short ar_hrd; /* format of hardware address */ 21 #define ARPHRD_ETHER 1 /* ethernet hardware address */ 22 u_short ar_pro; /* format of protocol address */ 23 u_char ar_hln; /* length of hardware address */ 24 u_char ar_pln; /* length of protocol address */ 25 u_short ar_op; /* one of: */ 26 #define ARPOP_REQUEST 1 /* request to resolve address */ 27 #define ARPOP_REPLY 2 /* response to previous request */ 28 /* 29 * The remaining fields are variable in size, 30 * according to the sizes above. 31 */ 32 /* u_char ar_sha[]; /* sender hardware address */ 33 /* u_char ar_spa[]; /* sender protocol address */ 34 /* u_char ar_tha[]; /* target hardware address */ 35 /* u_char ar_tpa[]; /* target protocol address */ 36 }; 37 38 /* 39 * ARP ioctl request 40 */ 41 struct arpreq { 42 struct sockaddr arp_pa; /* protocol address */ 43 struct sockaddr arp_ha; /* hardware address */ 44 int arp_flags; /* flags */ 45 }; 46 /* arp_flags and at_flags field values */ 47 #define ATF_INUSE 0x01 /* entry in use */ 48 #define ATF_COM 0x02 /* completed entry (enaddr valid) */ 49 #define ATF_PERM 0x04 /* permanent entry */ 50 #define ATF_PUBL 0x08 /* publish entry (respond for other host) */ 51 #define ATF_USETRAILERS 0x10 /* has requested trailers */ 52