net/inet/eth.c

/* */
This source file includes following definitions.
eth_setup
eth_header
eth_rebuild_header
eth_type_trans
   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  *
  27  *              This program is free software; you can redistribute it and/or
  28  *              modify it under the terms of the GNU General Public License
  29  *              as published by the Free Software Foundation; either version
  30  *              2 of the License, or (at your option) any later version.
  31  */
  32 #include <asm/segment.h>
  33 #include <asm/system.h>
  34 #include <linux/types.h>
  35 #include <linux/kernel.h>
  36 #include <linux/sched.h>
  37 #include <linux/string.h>
  38 #include <linux/mm.h>
  39 #include <linux/socket.h>
  40 #include <linux/in.h>
  41 #include <linux/inet.h>
  42 #include <linux/netdevice.h>
  43 #include <linux/etherdevice.h>
  44 #include <linux/skbuff.h>
  45 #include <linux/errno.h>
  46 #include "arp.h"
  47 
  48 void eth_setup(char *str, int *ints)
     /*  */
  49 {
  50         struct device *d = dev_base;
  51 
  52         if (!str || !*str)
  53                 return;
  54         while (d) 
  55         {
  56                 if (!strcmp(str,d->name)) 
  57                 {
  58                         if (ints[0] > 0)
  59                                 d->irq=ints[1];
  60                         if (ints[0] > 1)
  61                                 d->base_addr=ints[2];
  62                         if (ints[0] > 2)
  63                                 d->mem_start=ints[3];
  64                         if (ints[0] > 3)
  65                                 d->mem_end=ints[4];
  66                         break;
  67                 }
  68                 d=d->next;
  69         }
  70 }
  71 
  72 
  73 /*
  74  *       Create the Ethernet MAC header for an arbitary protocol layer 
  75  *
  76  *      saddr=NULL      means use device source address
  77  *      daddr=NULL      means leave destination address (eg unresolved arp)
  78  */
  79 
  80 int eth_header(unsigned char *buff, struct device *dev, unsigned short type,
     /*  */
  81            void *daddr, void *saddr, unsigned len,
  82            struct sk_buff *skb)
  83 {
  84         struct ethhdr *eth = (struct ethhdr *)buff;
  85 
  86         /* 
  87          *      Set the protocol type. For a packet of type ETH_P_802_3 we put the length
  88          *      in here instead. It is up to the 802.2 layer to carry protocol information.
  89          */
  90         
  91         if(type!=ETH_P_802_3) 
  92                 eth->h_proto = htons(type);
  93         else
  94                 eth->h_proto = htons(len);
  95 
  96         /*
  97          *      Set the source hardware address. 
  98          */
  99          
 100         if(saddr)
 101                 memcpy(eth->h_source,saddr,dev->addr_len);
 102         else
 103                 memcpy(eth->h_source,dev->dev_addr,dev->addr_len);
 104 
 105         /*
 106          *      Anyway, the loopback-device should never use this function... 
 107          */
 108 
 109         if (dev->flags & IFF_LOOPBACK) 
 110         {
 111                 memset(eth->h_dest, 0, dev->addr_len);
 112                 return(dev->hard_header_len);
 113         }
 114         
 115         if(daddr)
 116         {
 117                 memcpy(eth->h_dest,daddr,dev->addr_len);
 118                 return dev->hard_header_len;
 119         }
 120         
 121         return -dev->hard_header_len;
 122 }
 123 
 124 
 125 /*
 126  *      Rebuild the Ethernet MAC header. This is called after an ARP
 127  *      (or in future other address resolution) has completed on this
 128  *      sk_buff. We now let ARP fill in the other fields.
 129  */
 130  
 131 int eth_rebuild_header(void *buff, struct device *dev, unsigned long dst,
     /*  */
 132                         struct sk_buff *skb)
 133 {
 134         struct ethhdr *eth = (struct ethhdr *)buff;
 135 
 136         /*
 137          *      Only ARP/IP is currently supported
 138          */
 139          
 140         if(eth->h_proto != htons(ETH_P_IP)) 
 141         {
 142                 printk("eth_rebuild_header: Don't know how to resolve type %d addreses?\n",(int)eth->h_proto);
 143                 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
 144                 return 0;
 145         }
 146 
 147         /*
 148          *      Try and get ARP to resolve the header.
 149          */
 150          
 151         return arp_find(eth->h_dest, dst, dev, dev->pa_addr, skb)? 1 : 0;
 152 }
 153 
 154 
 155 /*
 156  *      Determine the packet's protocol ID. The rule here is that we 
 157  *      assume 802.3 if the type field is short enough to be a length.
 158  *      This is normal practice and works for any 'now in use' protocol.
 159  */
 160  
 161 unsigned short eth_type_trans(struct sk_buff *skb, struct device *dev)
     /*  */
 162 {
 163         struct ethhdr *eth = (struct ethhdr *) skb->data;
 164 
 165         if (ntohs(eth->h_proto) < 1536)
 166                 return htons(ETH_P_802_3);
 167 
 168         return eth->h_proto;
 169 }
 170
/* */
root/net/inet/eth.c

DEFINITIONS
