1 /* 2 * Copyright (c) 1986, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)if_arp.h 8.1 (Berkeley) 06/10/93 8 */ 9 10 /* 11 * Address Resolution Protocol. 12 * 13 * See RFC 826 for protocol description. ARP packets are variable 14 * in size; the arphdr structure defines the fixed-length portion. 15 * Protocol type values are the same as those for 10 Mb/s Ethernet. 16 * It is followed by the variable-sized fields ar_sha, arp_spa, 17 * arp_tha and arp_tpa in that order, according to the lengths 18 * specified. Field names used correspond to RFC 826. 19 */ 20 struct arphdr { 21 u_short ar_hrd; /* format of hardware address */ 22 #define ARPHRD_ETHER 1 /* ethernet hardware format */ 23 #define ARPHRD_FRELAY 15 /* frame relay hardware format */ 24 u_short ar_pro; /* format of protocol address */ 25 u_char ar_hln; /* length of hardware address */ 26 u_char ar_pln; /* length of protocol address */ 27 u_short ar_op; /* one of: */ 28 #define ARPOP_REQUEST 1 /* request to resolve address */ 29 #define ARPOP_REPLY 2 /* response to previous request */ 30 #define ARPOP_REVREQUEST 3 /* request protocol address given hardware */ 31 #define ARPOP_REVREPLY 4 /* response giving protocol address */ 32 #define ARPOP_INVREQUEST 8 /* request to identify peer */ 33 #define ARPOP_INVREPLY 9 /* response identifying peer */ 34 /* 35 * The remaining fields are variable in size, 36 * according to the sizes above. 37 */ 38 #ifdef COMMENT_ONLY 39 u_char ar_sha[]; /* sender hardware address */ 40 u_char ar_spa[]; /* sender protocol address */ 41 u_char ar_tha[]; /* target hardware address */ 42 u_char ar_tpa[]; /* target protocol address */ 43 #endif 44 }; 45 46 /* 47 * ARP ioctl request 48 */ 49 struct arpreq { 50 struct sockaddr arp_pa; /* protocol address */ 51 struct sockaddr arp_ha; /* hardware address */ 52 int arp_flags; /* flags */ 53 }; 54 /* arp_flags and at_flags field values */ 55 #define ATF_INUSE 0x01 /* entry in use */ 56 #define ATF_COM 0x02 /* completed entry (enaddr valid) */ 57 #define ATF_PERM 0x04 /* permanent entry */ 58 #define ATF_PUBL 0x08 /* publish entry (respond for other host) */ 59 #define ATF_USETRAILERS 0x10 /* has requested trailers */ 60