arp_send.c

来自「一款类linux的操作系统源码」· C语言 代码 · 共 69 行

/*
 *  Roadrunner/pk
 *    Copyright (C) 1989-2002  Cornfed Systems, Inc.
 *
 *  The Roadrunner/pk operating system is free software; you can
 *  redistribute and/or modify it under the terms of the GNU General
 *  Public License, version 2, as published by the Free Software
 *  Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public
 *  License along with this program; if not, write to the Free
 *  Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 *  MA 02111-1307 USA
 *
 *  More information about the Roadrunner/pk operating system of
 *  which this file is a part is available on the World-Wide Web
 *  at: http://www.cornfed.com.
 *
 */

#include <net/arp.h>
#include <net/netif.h>
#include <stdlib.h>
#include <string.h>

void
arp_send(ipaddr dst)
{
    buf_t b;
    etherhdr_t eh;
    arphdr_t ah;

    b = _bget(ETHER_PKT_LEN);
    if (b == NULL)
	return;
    blen(b) = ETHER_HDR_LEN + sizeof(struct arphdr);

    eh = (etherhdr_t) bstart(b);
    ah = (arphdr_t) eh->data;

    /* Format ARP request */
    ah->hwtype = ARP_HW_ETHERNET;
    ah->prtype = ETHER_TYPE_IP;
    ah->hwlen = ETHER_ADDR_LEN;
    ah->prlen = sizeof(ipaddr);
    ah->op = ARP_OP_REQUEST;
    bcopy(netif_primary.hwaddr, ah->sha, ETHER_ADDR_LEN);
    ah->spa = netif_primary.ip;
    bzero(ah->tha, ETHER_ADDR_LEN);
    ah->tpa = dst;

    /* Convert to network order */
    ah->hwtype = HS2NET(ah->hwtype);
    ah->prtype = HS2NET(ah->prtype);
    ah->op = HS2NET(ah->op);
    ah->spa = HL2NET(ah->spa);
    ah->tpa = HL2NET(ah->tpa);

    /* Send ARP request */
    memset(eh->dst, 0xff, ETHER_ADDR_LEN);
    eh->type = HS2NET(ETHER_TYPE_ARP);
    netif_send(b);
}