Il CD di internet/CD.iso/SOURCE/KERNEL-S/V1.2/LINUX-1.2/LINUX-1/linux/net/inet/eth.c

C/C++ Source or Header | 1995-01-24 | 4.7 KB | 197 lines

/*
 * INET        An implementation of the TCP/IP protocol suite for the LINUX
 *        operating system.  INET is implemented using the  BSD Socket
 *        interface as the means of communication with the user level.
 *
 *        Ethernet-type device handling.
 *
 * Version:    @(#)eth.c    1.0.7    05/25/93
 *
 * Authors:    Ross Biro, <[e-mail]>
 *        Fred N. van Kempen, <[e-mail]>
 *        Mark Evans, <[e-mail]>
 *        Florian  La Roche, <[e-mail]>
 *        Alan Cox, <[e-mail]>
 *
 * Fixes:
 *        Mr Linux    : Arp problems
 *        Alan Cox    : Generic queue tidyup (very tiny here)
 *        Alan Cox    : eth_header ntohs should be htons
 *        Alan Cox    : eth_rebuild_header missing an htons and
 *                  minor other things.
 *        Tegge        : Arp bug fixes.
 *        Florian        : Removed many unnecessary functions, code cleanup
 *                  and changes for new arp and skbuff.
 *        Alan Cox    : Redid header building to reflect new format.
 *        Alan Cox    : ARP only when compiled with CONFIG_INET
 *        Greg Page    : 802.2 and SNAP stuff
 *
 *        This program is free software; you can redistribute it and/or
 *        modify it under the terms of the GNU General Public License
 *        as published by the Free Software Foundation; either version
 *        2 of the License, or (at your option) any later version.
 */
#include <asm/segment.h>
#include <asm/system.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/errno.h>
#include <linux/config.h>

#include "arp.h"

void eth_setup(char *str, int *ints)
{
    struct device *d = dev_base;

    if (!str || !*str)
        return;
    while (d)
    {
        if (!strcmp(str,d->name))
        {
            if (ints[0] > 0)
                d->irq=ints[1];
            if (ints[0] > 1)
                d->base_addr=ints[2];
            if (ints[0] > 2)
                d->mem_start=ints[3];
            if (ints[0] > 3)
                d->mem_end=ints[4];
            break;
        }
        d=d->next;
    }
}


/*
 *     Create the Ethernet MAC header for an arbitrary protocol layer
 *
 *    saddr=NULL    means use device source address
 *    daddr=NULL    means leave destination address (eg unresolved arp)
 */

int eth_header(unsigned char *buff, struct device *dev, unsigned short type,
       void *daddr, void *saddr, unsigned len,
       struct sk_buff *skb)
{
    struct ethhdr *eth = (struct ethhdr *)buff;

    /*
     *    Set the protocol type. For a packet of type ETH_P_802_3 we put the length
     *    in here instead. It is up to the 802.2 layer to carry protocol information.
     */

    if(type!=ETH_P_802_3)
        eth->h_proto = htons(type);
    else
        eth->h_proto = htons(len);

    /*
     *    Set the source hardware address.
     */

    if(saddr)
        memcpy(eth->h_source,saddr,dev->addr_len);
    else
        memcpy(eth->h_source,dev->dev_addr,dev->addr_len);

    /*
     *    Anyway, the loopback-device should never use this function...
     */

    if (dev->flags & IFF_LOOPBACK)
    {
        memset(eth->h_dest, 0, dev->addr_len);
        return(dev->hard_header_len);
    }

    if(daddr)
    {
        memcpy(eth->h_dest,daddr,dev->addr_len);
        return dev->hard_header_len;
    }

    return -dev->hard_header_len;
}


/*
 *    Rebuild the Ethernet MAC header. This is called after an ARP
 *    (or in future other address resolution) has completed on this
 *    sk_buff. We now let ARP fill in the other fields.
 */

int eth_rebuild_header(void *buff, struct device *dev, unsigned long dst,
            struct sk_buff *skb)
{
    struct ethhdr *eth = (struct ethhdr *)buff;

    /*
     *    Only ARP/IP is currently supported
     */

    if(eth->h_proto != htons(ETH_P_IP))
    {
        printk("eth_rebuild_header: Don't know how to resolve type %d addresses?\n",(int)eth->h_proto);
        memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
        return 0;
    }

    /*
     *    Try and get ARP to resolve the header.
     */
#ifdef CONFIG_INET
    return arp_find(eth->h_dest, dst, dev, dev->pa_addr, skb)? 1 : 0;
#else
    return 0;
#endif
}


/*
 *    Determine the packet's protocol ID. The rule here is that we
 *    assume 802.3 if the type field is short enough to be a length.
 *    This is normal practice and works for any 'now in use' protocol.
 */

unsigned short eth_type_trans(struct sk_buff *skb, struct device *dev)
{
    struct ethhdr *eth = (struct ethhdr *) skb->data;
    unsigned char *rawp;

    if(*eth->h_dest&1)
    {
        if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
            skb->pkt_type=PACKET_BROADCAST;
        else
            skb->pkt_type=PACKET_MULTICAST;
    }

    if(dev->flags&IFF_PROMISC)
    {
        if(memcmp(eth->h_dest,dev->dev_addr, ETH_ALEN))
            skb->pkt_type=PACKET_OTHERHOST;
    }

    if (ntohs(eth->h_proto) >= 1536)
        return eth->h_proto;

    rawp = (unsigned char *)(eth + 1);

    if (*(unsigned short *)rawp == 0xFFFF)
        return htons(ETH_P_802_3);

    return htons(ETH_P_802_2);
}