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/*

 * 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, <bir7@leland.Stanford.Edu>

 *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>

 *              Mark Evans, <evansmp@uhura.aston.ac.uk>

 *              Florian  La Roche, <rzsfl@rz.uni-sb.de>

 *              Alan Cox, <gw4pts@gw4pts.ampr.org>

 *

 * 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.

 *              Alan Cox        : MAC layer pointers/new format.

 *              Paul Gortmaker  : eth_copy_and_sum shouldn't csum padding.

 *              Alan Cox        : Protect against forwarding explosions with

 *                                older network drivers and IFF_ALLMULTI.

 *      Christer Weinigel       : Better rebuild header message.

 *             Andrew Morton    : 26Feb01: kill ether_setup() - use netdev_boot_setup().

 *

 *              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 <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/ip.h>

#include <linux/netdevice.h>

#include <linux/etherdevice.h>

#include <linux/skbuff.h>

#include <linux/errno.h>

#include <linux/config.h>

#include <linux/init.h>

#include <net/dst.h>

#include <net/arp.h>

#include <net/sock.h>

#include <net/ipv6.h>

#include <net/ip.h>

#include <asm/uaccess.h>

#include <asm/system.h>

#include <asm/checksum.h>

extern int __init netdev_boot_setup(char *str);

__setup("ether=", netdev_boot_setup);

/*

 *       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(struct sk_buff *skb, struct net_device *dev, unsigned short type,

           void *daddr, void *saddr, unsigned len)

{

        struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN);

        /*

         *      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|IFF_NOARP))

        {

                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.

 *

 *      This routine CANNOT use cached dst->neigh!

 *      Really, it is used only when dst->neigh is wrong.

 */

int eth_rebuild_header(struct sk_buff *skb)

{

        struct ethhdr *eth = (struct ethhdr *)skb->data;

        struct net_device *dev = skb->dev;

        switch (eth->h_proto)

        {

#ifdef CONFIG_INET

        case __constant_htons(ETH_P_IP):

                return arp_find(eth->h_dest, skb);

#endif  

        default:

                printk(KERN_DEBUG

                       "%s: unable to resolve type %X addresses.\n",

                       dev->name, (int)eth->h_proto);

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

                break;

        }

        return 0;

}

/*

 *      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 net_device *dev)

{

        struct ethhdr *eth;

        unsigned char *rawp;

        skb->mac.raw=skb->data;

        skb_pull(skb,dev->hard_header_len);

        eth= skb->mac.ethernet;

        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;

        }

        /*

         *      This ALLMULTI check should be redundant by 1.4

         *      so don't forget to remove it.

         *

         *      Seems, you forgot to remove it. All silly devices

         *      seems to set IFF_PROMISC.

         */

        else if(1 /*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 = skb->data;

        /*

         *      This is a magic hack to spot IPX packets. Older Novell breaks

         *      the protocol design and runs IPX over 802.3 without an 802.2 LLC

         *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This

         *      won't work for fault tolerant netware but does for the rest.

         */

        if (*(unsigned short *)rawp == 0xFFFF)

                return htons(ETH_P_802_3);

        /*

         *      Real 802.2 LLC

         */

        return htons(ETH_P_802_2);

}

int eth_header_parse(struct sk_buff *skb, unsigned char *haddr)

{

        struct ethhdr *eth = skb->mac.ethernet;

        memcpy(haddr, eth->h_source, ETH_ALEN);

        return ETH_ALEN;

}

int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh)

{

        unsigned short type = hh->hh_type;

        struct ethhdr *eth;

        struct net_device *dev = neigh->dev;

        eth = (struct ethhdr*)

                (((u8*)hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));

        if (type == __constant_htons(ETH_P_802_3))

                return -1;

        eth->h_proto = type;

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

        memcpy(eth->h_dest, neigh->ha, dev->addr_len);

        hh->hh_len = ETH_HLEN;

        return 0;

}

/*

 * Called by Address Resolution module to notify changes in address.

 */

void eth_header_cache_update(struct hh_cache *hh, struct net_device *dev, unsigned char * haddr)

{

        memcpy(((u8*)hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),

               haddr, dev->addr_len);

}