arp.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 <stdlib.h>
#include <string.h>
#include <sys/intr.h>
#include <sys/time.h>
#include <sys/timer.h>

#define ARP_TIMER_PERIOD	5

struct arpentry arptab[ARP_ENTRIES];

static void
arp_timer(void *arg)
{
    arpentry_t ae;
    int i;

    for (i = 0; i < ARP_ENTRIES; i++) {
	ae = &(arptab[i]);

	if (ae->state == ARP_ENTRY_PENDING) {
	    ae->ttl -= ARP_TIMER_PERIOD;
	    if (ae->ttl <= 0) {
		ae->ttl = ARP_TTL_PENDING;
		enable;
		arp_send(ae->ip);
		disable;
	    }
	} else if (ae->state == ARP_ENTRY_RESOLVED &&
		   ae->ttl != ARP_TTL_INFINITE) {
	    ae->ttl -= ARP_TIMER_PERIOD;
	    if (ae->ttl == 0) {
		buf_t b;

		for (;;) {
		    b = bdeq(&(ae->pktq));
		    if (b == NULL)
			break;
		    brel(b);
		}
		bzero(ae, sizeof(struct arpentry));
	    }
	}
    }
}

void
arp_init()
{
    struct timeval tv;

    bzero(arptab, ARP_ENTRIES * sizeof(struct arpentry));

    tv.tv_sec = ARP_TIMER_PERIOD;
    tv.tv_usec = 0;
    timer_loop("arp", &tv, arp_timer, NULL);
}