ip_send.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/ether.h>
#include <net/ip.h>
#include <net/netif.h>
#include <stdlib.h>
#include <string.h>
#include <sys/intr.h>

u_short cksum(void *buf, int len);

//2002年09月12日增加
u_short cksum(void *buf, int len)
{
}



void
ip_send(buf_t b, u_short len, u_char pr, ipaddr src, ipaddr dst)
{
    etherhdr_t eh = (etherhdr_t) bstart(b);
    iphdr_t ih = (iphdr_t) eh->data;
    arpentry_t ae;

    /* Format and send IP packet */
    ih->ver = (IP_VERSION << 4) | (sizeof(struct iphdr) >> 2);

    ih->tos = 0;
    ih->len = sizeof(struct iphdr) + len;

    ih->id = 0;
    ih->off = 0;
    ih->ttl = 255;
    ih->pr = pr;
    ih->cksum = 0;
    ih->src = src;
    ih->dst = dst;

    /* Convert to network order */
    ih->len = HS2NET(ih->len);
    ih->src = HL2NET(ih->src);
    ih->dst = HL2NET(ih->dst);

    /* Compute header checksum */
    ih->cksum = cksum(ih, sizeof(struct iphdr));

    eh->type = HS2NET(ETHER_TYPE_IP);

    /* Locate an ARP entry for destination IP address in the packet */
    ae = arp_find(dst);
    if (ae == NULL) {
	etheraddr hwaddr;

	/* Setup a new ARP table entry */
	bzero(hwaddr, ETHER_ADDR_LEN);
	ae = arp_insert(ARP_ENTRY_PENDING, ARP_TTL_PENDING, dst, hwaddr);
	if (ae == NULL) {
	    /* No more ARP table entries */
	    brel(b);
	    return;
	}
	/* Send an ARP request */
	arp_send(dst);

	/* Queue the packet for transmission */
	disable;
	benq(b, &(ae->pktq));
	enable;
	return;
    }
    /* Send IP packet */
    bcopy(ae->hwaddr, eh->dst, ETHER_ADDR_LEN);
    netif_send(b);
}