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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.

 *              Russell King    : eth_header_cache_bind and eth_header_cache_update

 *                                only compiled if CONFIG_INET is selected

 *

 *              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 <net/arp.h>

#include <net/sock.h>

#include <asm/checksum.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(struct sk_buff *skb, struct 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)

        {

                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(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);

                return 0;

        }

        /*

         *      Try to 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;

        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.

         */

        else if(dev->flags&(IFF_PROMISC|IFF_ALLMULTI))

        {

                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);

}

#ifdef CONFIG_INET

/*

 * Upper level calls this function to bind hardware header cache entry.

 * If the call is successful, then corresponding Address Resolution Protocol

 * (maybe, not ARP) takes responsibility for updating cache content.

 */

void eth_header_cache_bind(struct hh_cache ** hhp, struct device *dev,

                           unsigned short htype, __u32 daddr)

{

        struct hh_cache *hh;

        if (htype != ETH_P_IP)

        {

                printk(KERN_DEBUG "eth_header_cache_bind: %04x cache is not implemented\n", htype);

                return;

        }

        if (arp_bind_cache(hhp, dev, htype, daddr))

                return;

        if ((hh=*hhp) != NULL)

        {

                memcpy(hh->hh_data+6, dev->dev_addr, ETH_ALEN);

                hh->hh_data[12] = htype>>8;

                hh->hh_data[13] = htype&0xFF;

        }

}

/*

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

 */

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

{

        if (hh->hh_type != ETH_P_IP)

        {

                printk(KERN_DEBUG "eth_header_cache_update: %04x cache is not implemented\n", hh->hh_type);

                return;

        }

        memcpy(hh->hh_data, haddr, ETH_ALEN);

        hh->hh_uptodate = 1;

}

#endif

/*

 *      Copy from an ethernet device memory space to an sk_buff while checksumming if IP

 */

void eth_copy_and_sum(struct sk_buff *dest, unsigned char *src, int length, int base)

{

#ifdef CONFIG_IP_ROUTER

        memcpy(dest->data,src,length);

#else

        struct ethhdr *eth;

        struct iphdr *iph;

        int ip_length;

        IS_SKB(dest);

        eth=(struct ethhdr *)src;

        if(eth->h_proto!=htons(ETH_P_IP))

        {

                memcpy(dest->data,src,length);

                return;

        }

        /*

         * We have to watch for padded packets. The csum doesn't include the

         * padding, and there is no point in copying the padding anyway.

         * We have to use the smaller of length and ip_length because it

         * can happen that ip_length > length.

         */

        memcpy(dest->data,src,sizeof(struct iphdr)+ETH_HLEN);   /* ethernet is always >= 34 */

        length -= sizeof(struct iphdr) + ETH_HLEN;

        iph=(struct iphdr*)(src+ETH_HLEN);

        ip_length = ntohs(iph->tot_len) - sizeof(struct iphdr);

        /* Also watch out for bogons - min IP size is 8 (rfc-1042) */

        if ((ip_length <= length) && (ip_length > 7))

                length=ip_length;

        dest->csum=csum_partial_copy(src+sizeof(struct iphdr)+ETH_HLEN,dest->data+sizeof(struct iphdr)+ETH_HLEN,length,base);

        dest->ip_summed=1;

#endif  

}