if_arp.h

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#ifndef _GPXE_IF_ARP_H
#define _GPXE_IF_ARP_H

/** @file
 *
 * Address Resolution Protocol constants and types
 *
 */

FILE_LICENCE ( GPL2_OR_LATER );

#include <stdint.h>

/* ARP protocol HARDWARE identifiers. */
#define ARPHRD_NETROM   0               /**< from KA9Q: NET/ROM pseudo  */
#define ARPHRD_ETHER    1               /**< Ethernet 10Mbps            */
#define ARPHRD_EETHER   2               /**< Experimental Ethernet      */
#define ARPHRD_AX25     3               /**< AX.25 Level 2              */
#define ARPHRD_PRONET   4               /**< PROnet token ring          */
#define ARPHRD_CHAOS    5               /**< Chaosnet                   */
#define ARPHRD_IEEE802  6               /**< IEEE 802.2 Ethernet/TR/TB  */
#define ARPHRD_ARCNET   7               /**< ARCnet                     */
#define ARPHRD_APPLETLK 8               /**< APPLEtalk                  */
#define ARPHRD_DLCI     15              /**< Frame Relay DLCI           */
#define ARPHRD_ATM      19              /**< ATM                        */
#define ARPHRD_METRICOM 23              /**< Metricom STRIP (new IANA id) */
#define ARPHRD_IEEE1394 24              /**< IEEE 1394 IPv4 - RFC 2734  */
#define ARPHRD_EUI64    27              /**< EUI-64                     */
#define ARPHRD_INFINIBAND 32            /**< InfiniBand                 */

/* ARP protocol opcodes. */
#define ARPOP_REQUEST   1               /**< ARP request                */
#define ARPOP_REPLY     2               /**< ARP reply                  */
#define ARPOP_RREQUEST  3               /**< RARP request               */
#define ARPOP_RREPLY    4               /**< RARP reply                 */
#define ARPOP_InREQUEST 8               /**< InARP request              */
#define ARPOP_InREPLY   9               /**< InARP reply                */
#define ARPOP_NAK       10              /**< (ATM)ARP NAK               */

/**
 * An ARP header
 *
 * This contains only the fixed-size portions of an ARP header; for
 * other fields use the arp_{sender,target}_{ha,pa} family of
 * functions.
 */
struct arphdr {
        /** Link-layer protocol
         *
         * This is an ARPHRD_XXX constant
         */
        uint16_t ar_hrd;
        /** Network-layer protocol
         *
         * This is, for Ethernet, an ETH_P_XXX constant.
         */
        uint16_t ar_pro;
        /** Link-layer address length */
        uint8_t ar_hln;
        /** Network-layer address length */
        uint8_t ar_pln;
        /** ARP opcode */
        uint16_t ar_op;
} __attribute__ (( packed ));

/** ARP packet sender hardware address
 *
 * @v arphdr    ARP header
 * @ret ar_sha  Sender hardware address
 */
static inline void * arp_sender_ha ( struct arphdr *arphdr ) {
        return ( ( ( void * ) arphdr ) + sizeof ( *arphdr ) );
}

/** ARP packet sender protocol address
 *
 * @v arphdr    ARP header
 * @ret ar_spa  Sender protocol address
 */
static inline void * arp_sender_pa ( struct arphdr *arphdr ) {
        return ( arp_sender_ha ( arphdr ) + arphdr->ar_hln );
}

/** ARP packet target hardware address
 *
 * @v arphdr    ARP header
 * @ret ar_tha  Target hardware address
 */
static inline void * arp_target_ha ( struct arphdr *arphdr ) {
        return ( arp_sender_pa ( arphdr ) + arphdr->ar_pln );
}

/** ARP packet target protocol address
 *
 * @v arphdr    ARP header
 * @ret ar_tpa  Target protocol address
 */
static inline void * arp_target_pa ( struct arphdr *arphdr ) {
        return ( arp_target_ha ( arphdr ) + arphdr->ar_hln );
}

#endif  /* _GPXE_IF_ARP_H */