arp_input.c

一款类linux的操作系统源码

/*
 *  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>
#if _DEBUG_ARP
#include <stdio.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <sys/intr.h>

void
arp_input(buf_t b)
{
    etherhdr_t eh = (etherhdr_t) bstart(b);
    arphdr_t ah = (arphdr_t) eh->data;
    arpentry_t ae;

    ah->hwtype = NET2HS(ah->hwtype);
    ah->prtype = NET2HS(ah->prtype);
    if (ah->hwtype != ARP_HW_ETHERNET || ah->prtype != ETHER_TYPE_IP ||
	ah->hwlen != ETHER_ADDR_LEN || ah->prlen != sizeof(ipaddr)) {
	brel(b);
	return;
    }
    switch (NET2HS(ah->op)) {
    case ARP_OP_REQUEST:
#if _DEBUG_ARP
	{
	    ipaddr ip1, ip2;
	    char s1[32], s2[32];

	    ip1 = NET2HL(ah->tpa);
	    ip2 = NET2HL(ah->spa);
	    kprintf("arp_input: who has %s tell %s\n",
		    ip2str(ip1, s1), ip2str(ip2, s2));
	}
#endif
	ah->tpa = NET2HL(ah->tpa);
	ae = arp_find(ah->tpa);
	if (ae == NULL) {
	    brel(b);
	    return;
	}
	/* Format and send an ARP reply */
	ah->hwtype = HS2NET(ah->hwtype);
	ah->prtype = HS2NET(ah->prtype);
	ah->op = HS2NET(ARP_OP_REPLY);
	ah->tpa = ah->spa;
	ah->spa = HL2NET(netif_primary.ip);
	bcopy(ah->sha, ah->tha, ETHER_ADDR_LEN);
	bcopy(ah->tha, eh->dst, ETHER_ADDR_LEN);
	bcopy(netif_primary.hwaddr, ah->sha, ETHER_ADDR_LEN);
	netif_send(b);
	break;

    case ARP_OP_REPLY:
	ah->spa = NET2HL(ah->spa);
	ae = arp_find(ah->spa);
	if (ae != NULL && ae->state == ARP_ENTRY_PENDING) {
#if _DEBUG_ARP
	    {
		char s1[20], s2[20];

		ip2str(ah->spa, s1);
		ether2str(ah->sha, s2);
		kprintf("arp_input: %s is at %s\n", s1, s2);
	    }
#endif
	    /* Update ARP entry */
	    bcopy(ah->sha, ae->hwaddr, ETHER_ADDR_LEN);
	    ae->state = ARP_ENTRY_RESOLVED;
	    ae->ttl = ARP_TTL_RESOLVED;

	    /* Send any queued packets */
	    brel(b);
	    for (;;) {
		disable;
		b = bdeq(&(ae->pktq));
		enable;

		if (b == NULL)
		    break;
		eh = (etherhdr_t) bstart(b);
		bcopy(ae->hwaddr, eh->dst, ETHER_ADDR_LEN);
		netif_send(b);
	    }
	} else
	    brel(b);

	break;

    default:
#if _DEBUG_ARP
	kprintf("arp_input: unsupported opcode (%04x)\n", NET2HS(ah->op));
#endif
	brel(b);
    }
}