net/ethernet/eth.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Ethernet-type device handling.
   7  *
   8  * Version:     @(#)eth.c       1.0.7   05/25/93
   9  *
  10  * Authors:     Ross Biro, <bir7@leland.Stanford.Edu>
  11  *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  12  *              Mark Evans, <evansmp@uhura.aston.ac.uk>
  13  *              Florian  La Roche, <rzsfl@rz.uni-sb.de>
  14  *              Alan Cox, <gw4pts@gw4pts.ampr.org>
  15  *
  16  * Fixes:
  17  *              Mr Linux        : Arp problems
  18  *              Alan Cox        : Generic queue tidyup (very tiny here)
  19  *              Alan Cox        : eth_header ntohs should be htons
  20  *              Alan Cox        : eth_rebuild_header missing an htons and
  21  *                                minor other things.
  22  *              Tegge           : Arp bug fixes.
  23  *              Florian         : Removed many unnecessary functions, code cleanup
  24  *                                and changes for new arp and skbuff.
  25  *              Alan Cox        : Redid header building to reflect new format.
  26  *              Alan Cox        : ARP only when compiled with CONFIG_INET
  27  *              Greg Page       : 802.2 and SNAP stuff.
  28  *              Alan Cox        : MAC layer pointers/new format.
  29  *              Paul Gortmaker  : eth_copy_and_sum shouldn't csum padding.
  30  *              Alan Cox        : Protect against forwarding explosions with
  31  *                                older network drivers and IFF_ALLMULTI.
  32  *      Christer Weinigel       : Better rebuild header message.
  33  *
  34  *              This program is free software; you can redistribute it and/or
  35  *              modify it under the terms of the GNU General Public License
  36  *              as published by the Free Software Foundation; either version
  37  *              2 of the License, or (at your option) any later version.
  38  */
  39 #include <linux/types.h>
  40 #include <linux/kernel.h>
  41 #include <linux/sched.h>
  42 #include <linux/string.h>
  43 #include <linux/mm.h>
  44 #include <linux/socket.h>
  45 #include <linux/in.h>
  46 #include <linux/inet.h>
  47 #include <linux/ip.h>
  48 #include <linux/netdevice.h>
  49 #include <linux/etherdevice.h>
  50 #include <linux/skbuff.h>
  51 #include <linux/errno.h>
  52 #include <linux/config.h>
  53 #include <linux/init.h>
  54 #include <net/dst.h>
  55 #include <net/arp.h>
  56 #include <net/sock.h>
  57 #include <net/ipv6.h>
  58 #include <net/ip.h>
  59 #include <asm/uaccess.h>
  60 #include <asm/system.h>
  61 #include <asm/checksum.h>
  62
  63
  64 __initfunc(void eth_setup(char *str, int *ints))
  65 {
  66         struct device *d;
  67
  68         if (!str || !*str)
  69                 return;
  70
  71         d = dev_base;
  72         while (d)
  73         {
  74                 if (!strcmp(str,d->name))
  75                 {
  76                         if (ints[0] > 0)
  77                                 d->irq=ints[1];
  78                         if (ints[0] > 1)
  79                                 d->base_addr=ints[2];
  80                         if (ints[0] > 2)
  81                                 d->mem_start=ints[3];
  82                         if (ints[0] > 3)
  83                                 d->mem_end=ints[4];
  84                         break;
  85                 }
  86                 d=d->next;
  87         }
  88 }
  89
  90
  91 /*
  92  *       Create the Ethernet MAC header for an arbitrary protocol layer
  93  *
  94  *      saddr=NULL      means use device source address
  95  *      daddr=NULL      means leave destination address (eg unresolved arp)
  96  */
  97
  98 int eth_header(struct sk_buff *skb, struct device *dev, unsigned short type,
  99            void *daddr, void *saddr, unsigned len)
 100 {
 101         struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN);
 102
 103         /*
 104          *      Set the protocol type. For a packet of type ETH_P_802_3 we put the length
 105          *      in here instead. It is up to the 802.2 layer to carry protocol information.
 106          */
 107
 108         if(type!=ETH_P_802_3)
 109                 eth->h_proto = htons(type);
 110         else
 111                 eth->h_proto = htons(len);
 112
 113         /*
 114          *      Set the source hardware address.
 115          */
 116
 117         if(saddr)
 118                 memcpy(eth->h_source,saddr,dev->addr_len);
 119         else
 120                 memcpy(eth->h_source,dev->dev_addr,dev->addr_len);
 121
 122         /*
 123          *      Anyway, the loopback-device should never use this function...
 124          */
 125
 126         if (dev->flags & (IFF_LOOPBACK|IFF_NOARP))
 127         {
 128                 memset(eth->h_dest, 0, dev->addr_len);
 129                 return(dev->hard_header_len);
 130         }
 131
 132         if(daddr)
 133         {
 134                 memcpy(eth->h_dest,daddr,dev->addr_len);
 135                 return dev->hard_header_len;
 136         }
 137
 138         return -dev->hard_header_len;
 139 }
 140
 141
 142 /*
 143  *      Rebuild the Ethernet MAC header. This is called after an ARP
 144  *      (or in future other address resolution) has completed on this
 145  *      sk_buff. We now let ARP fill in the other fields.
 146  *
 147  *      This routine CANNOT use cached dst->neigh!
 148  *      Really, it is used only when dst->neigh is wrong.
 149  */
 150
 151 int eth_rebuild_header(struct sk_buff *skb)
 152 {
 153         struct ethhdr *eth = (struct ethhdr *)skb->data;
 154         struct device *dev = skb->dev;
 155
 156         switch (eth->h_proto)
 157         {
 158 #ifdef CONFIG_INET
 159         case __constant_htons(ETH_P_IP):
 160                 return arp_find(eth->h_dest, skb);
 161 #endif
 162         default:
 163                 printk(KERN_DEBUG
 164                        "%s: unable to resolve type %X addresses.\n",
 165                        dev->name, (int)eth->h_proto);
 166
 167                 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 168                 break;
 169         }
 170
 171         return 0;
 172 }
 173
 174
 175 /*
 176  *      Determine the packet's protocol ID. The rule here is that we
 177  *      assume 802.3 if the type field is short enough to be a length.
 178  *      This is normal practice and works for any 'now in use' protocol.
 179  */
 180
 181 unsigned short eth_type_trans(struct sk_buff *skb, struct device *dev)
 182 {
 183         struct ethhdr *eth;
 184         unsigned char *rawp;
 185
 186         skb->mac.raw=skb->data;
 187         skb_pull(skb,dev->hard_header_len);
 188         eth= skb->mac.ethernet;
 189
 190         if(*eth->h_dest&1)
 191         {
 192                 if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
 193                         skb->pkt_type=PACKET_BROADCAST;
 194                 else
 195                         skb->pkt_type=PACKET_MULTICAST;
 196         }
 197
 198         /*
 199          *      This ALLMULTI check should be redundant by 1.4
 200          *      so don't forget to remove it.
 201          *
 202          *      Seems, you forgot to remove it. All silly devices
 203          *      seems to set IFF_PROMISC.
 204          */
 205
 206         else if(dev->flags&(IFF_PROMISC/*|IFF_ALLMULTI*/))
 207         {
 208                 if(memcmp(eth->h_dest,dev->dev_addr, ETH_ALEN))
 209                         skb->pkt_type=PACKET_OTHERHOST;
 210         }
 211
 212         if (ntohs(eth->h_proto) >= 1536)
 213                 return eth->h_proto;
 214
 215         rawp = skb->data;
 216
 217         /*
 218          *      This is a magic hack to spot IPX packets. Older Novell breaks
 219          *      the protocol design and runs IPX over 802.3 without an 802.2 LLC
 220          *      layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
 221          *      won't work for fault tolerant netware but does for the rest.
 222          */
 223         if (*(unsigned short *)rawp == 0xFFFF)
 224                 return htons(ETH_P_802_3);
 225
 226         /*
 227          *      Real 802.2 LLC
 228          */
 229         return htons(ETH_P_802_2);
 230 }
 231
 232 int eth_header_parse(struct sk_buff *skb, unsigned char *haddr)
 233 {
 234         struct ethhdr *eth = skb->mac.ethernet;
 235         memcpy(haddr, eth->h_source, ETH_ALEN);
 236         return ETH_ALEN;
 237 }
 238
 239 int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh)
 240 {
 241         unsigned short type = hh->hh_type;
 242         struct ethhdr *eth = (struct ethhdr*)(((u8*)hh->hh_data) + 2);
 243         struct device *dev = neigh->dev;
 244
 245         if (type == __constant_htons(ETH_P_802_3))
 246                 return -1;
 247
 248         eth->h_proto = type;
 249         memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 250         memcpy(eth->h_dest, neigh->ha, dev->addr_len);
 251         return 0;
 252 }
 253
 254 /*
 255  * Called by Address Resolution module to notify changes in address.
 256  */
 257
 258 void eth_header_cache_update(struct hh_cache *hh, struct device *dev, unsigned char * haddr)
 259 {
 260         memcpy(((u8*)hh->hh_data) + 2, haddr, dev->addr_len);
 261 }
 262
 263 #ifndef CONFIG_IP_ROUTER
 264
 265 /*
 266  *      Copy from an ethernet device memory space to an sk_buff while checksumming if IP
 267  */
 268
 269 void eth_copy_and_sum(struct sk_buff *dest, unsigned char *src, int length, int base)
 270 {
 271         struct ethhdr *eth;
 272         struct iphdr *iph;
 273         int ip_length;
 274
 275         eth=(struct ethhdr *)src;
 276         if(eth->h_proto!=htons(ETH_P_IP))
 277         {
 278                 memcpy(dest->data,src,length);
 279                 return;
 280         }
 281         /*
 282          * We have to watch for padded packets. The csum doesn't include the
 283          * padding, and there is no point in copying the padding anyway.
 284          * We have to use the smaller of length and ip_length because it
 285          * can happen that ip_length > length.
 286          */
 287         memcpy(dest->data,src,sizeof(struct iphdr)+ETH_HLEN);   /* ethernet is always >= 34 */
 288         length -= sizeof(struct iphdr) + ETH_HLEN;
 289         iph=(struct iphdr*)(src+ETH_HLEN);
 290         ip_length = ntohs(iph->tot_len) - sizeof(struct iphdr);
 291
 292         /* Also watch out for bogons - min IP size is 8 (rfc-1042) */
 293         if ((ip_length <= length) && (ip_length > 7))
 294                 length=ip_length;
 295
 296         dest->csum=csum_partial_copy(src+sizeof(struct iphdr)+ETH_HLEN,dest->data+sizeof(struct iphdr)+ETH_HLEN,length,base);
 297         dest->ip_summed=1;
 298 }
 299
 300 #endif /* !(CONFIG_IP_ROUTER) */