arp.h File Reference

Address Resolution Protocol. More...

#include <gpxe/tables.h>

Go to the source code of this file.

Data Structures
struct	arp_net_protocol
	A network-layer protocol that relies upon ARP. More...
Defines
#define	ARP_NET_PROTOCOLS   __table ( struct arp_net_protocol, "arp_net_protocols" )
	ARP protocol table.
#define	__arp_net_protocol   __table_entry ( ARP_NET_PROTOCOLS, 01 )
	Declare an ARP protocol.
Functions
	FILE_LICENCE (GPL2_OR_LATER)
int	arp_resolve (struct net_device *netdev, struct net_protocol *net_protocol, const void *dest_net_addr, const void *source_net_addr, void *dest_ll_addr)
	Look up media-specific link-layer address in the ARP cache.
Variables
struct net_protocol	arp_protocol

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Detailed Description

Address Resolution Protocol.

Definition in file arp.h.

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Define Documentation

#define ARP_NET_PROTOCOLS   __table ( struct arp_net_protocol, "arp_net_protocols" )

ARP protocol table.

Definition at line 32 of file arp.h.

Referenced by arp_find_protocol().

#define __arp_net_protocol   __table_entry ( ARP_NET_PROTOCOLS, 01 )

Declare an ARP protocol.

Definition at line 36 of file arp.h.

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Function Documentation

FILE_LICENCE

(

GPL2_OR_LATER

)

int arp_resolve	(	struct net_device *	netdev,
		struct net_protocol *	net_protocol,
		const void *	dest_net_addr,
		const void *	source_net_addr,
		void *	dest_ll_addr
	)

Look up media-specific link-layer address in the ARP cache.

Parameters:

	netdev	Network device
	net_protocol	Network-layer protocol
	dest_net_addr	Destination network-layer address
	source_net_addr	Source network-layer address

Return values:

	dest_ll_addr	Destination link layer address
	rc	Return status code

This function will use the ARP cache to look up the link-layer address for the link-layer protocol associated with the network device and the given network-layer protocol and addresses. If found, the destination link-layer address will be filled in in dest_ll_addr.

If no address is found in the ARP cache, an ARP request will be transmitted on the specified network device and -ENOENT will be returned.

Definition at line 113 of file arp.c.

References alloc_iob(), arphdr::ar_hln, arphdr::ar_hrd, arphdr::ar_op, arphdr::ar_pln, arphdr::ar_pro, arp_find_entry(), arp_protocol, ARPOP_REQUEST, DBG, ENOENT, ENOMEM, htons, iob_put, iob_reserve, net_device::ll_addr, arp_entry::ll_addr, ll_protocol::ll_addr_len, net_device::ll_broadcast, ll_protocol::ll_proto, net_device::ll_protocol, MAX_LL_ADDR_LEN, MAX_LL_HEADER_LEN, MAX_NET_ADDR_LEN, memcpy, memset(), ll_protocol::name, net_protocol::name, arp_entry::net_addr, net_protocol::net_addr_len, net_protocol::net_proto, net_tx(), ll_protocol::ntoa, and net_protocol::ntoa.

Referenced by ipv4_ll_addr().

                                       {
        struct ll_protocol *ll_protocol = netdev->ll_protocol;
        const struct arp_entry *arp;
        struct io_buffer *iobuf;
        struct arphdr *arphdr;
        int rc;

        /* Look for existing entry in ARP table */
        arp = arp_find_entry ( ll_protocol, net_protocol, dest_net_addr );
        if ( arp ) {
                DBG ( "ARP cache hit: %s %s => %s %s\n",
                      net_protocol->name, net_protocol->ntoa ( arp->net_addr ),
                      ll_protocol->name, ll_protocol->ntoa ( arp->ll_addr ) );
                memcpy ( dest_ll_addr, arp->ll_addr, ll_protocol->ll_addr_len);
                return 0;
        }
        DBG ( "ARP cache miss: %s %s\n", net_protocol->name,
              net_protocol->ntoa ( dest_net_addr ) );

        /* Allocate ARP packet */
        iobuf = alloc_iob ( MAX_LL_HEADER_LEN + sizeof ( *arphdr ) +
                          2 * ( MAX_LL_ADDR_LEN + MAX_NET_ADDR_LEN ) );
        if ( ! iobuf )
                return -ENOMEM;
        iob_reserve ( iobuf, MAX_LL_HEADER_LEN );

        /* Build up ARP request */
        arphdr = iob_put ( iobuf, sizeof ( *arphdr ) );
        arphdr->ar_hrd = ll_protocol->ll_proto;
        arphdr->ar_hln = ll_protocol->ll_addr_len;
        arphdr->ar_pro = net_protocol->net_proto;
        arphdr->ar_pln = net_protocol->net_addr_len;
        arphdr->ar_op = htons ( ARPOP_REQUEST );
        memcpy ( iob_put ( iobuf, ll_protocol->ll_addr_len ),
                 netdev->ll_addr, ll_protocol->ll_addr_len );
        memcpy ( iob_put ( iobuf, net_protocol->net_addr_len ),
                 source_net_addr, net_protocol->net_addr_len );
        memset ( iob_put ( iobuf, ll_protocol->ll_addr_len ),
                 0, ll_protocol->ll_addr_len );
        memcpy ( iob_put ( iobuf, net_protocol->net_addr_len ),
                 dest_net_addr, net_protocol->net_addr_len );

        /* Transmit ARP request */
        if ( ( rc = net_tx ( iobuf, netdev, &arp_protocol, 
                             netdev->ll_broadcast ) ) != 0 )
                return rc;

        return -ENOENT;
}

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Variable Documentation

struct net_protocol arp_protocol

Definition at line 66 of file arp.c.

Referenced by arp_resolve(), arp_rx(), pxenv_undi_isr(), and pxenv_undi_transmit().