eth.c

An implementation of the TCP/IP protocol suite for the LINUX operating system. INET is implemented u

  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, <[e-mail]>
 11  *              Fred N. van Kempen, <[e-mail]>
 12  *              Mark Evans, <[e-mail]>
 13  * 
 14  * Fixes:
 15  *              Mr Linux        : Arp problems
 16  *              Alan Cox        : Generic queue tidyup (very tiny here)
 17  *              Alan Cox        : eth_header ntohs should be htons
 18  *              Alan Cox        : eth_rebuild_header missing an htons and
 19  *                                minor other things.
 20  *              Tegge           : Arp bug fixes. 
 21  *
 22  *              This program is free software; you can redistribute it and/or
 23  *              modify it under the terms of the GNU General Public License
 24  *              as published by the Free Software Foundation; either version
 25  *              2 of the License, or (at your option) any later version.
 26  */
 27 #include <asm/segment.h>
 28 #include <asm/system.h>
 29 #include <linux/types.h>
 30 #include <linux/kernel.h>
 31 #include <linux/sched.h>
 32 #include <linux/string.h>
 33 #include <linux/mm.h>
 34 #include <linux/socket.h>
 35 #include <linux/in.h>
 36 #include "inet.h"
 37 #include "dev.h"
 38 #include "eth.h"
 39 #include "ip.h"
 40 #include "route.h"
 41 #include "protocol.h"
 42 #include "tcp.h"
 43 #include "skbuff.h"
 44 #include "sock.h"
 45 #include <linux/errno.h>
 46 #include "arp.h"
 47 
 48 
 49 /* Display an Ethernet address in readable format. */
 50 char *eth_print(unsigned char *ptr)
 51 {
 52   static char buff[64];
 53 
 54   if (ptr == NULL) return("[NONE]");
 55   sprintf(buff, "%02X:%02X:%02X:%02X:%02X:%02X",
 56         (ptr[0] & 255), (ptr[1] & 255), (ptr[2] & 255),
 57         (ptr[3] & 255), (ptr[4] & 255), (ptr[5] & 255)
 58   );
 59   return(buff);
 60 }
 61 
 62 void eth_setup(char *str, int *ints)
 63 {
 64         struct device *d = dev_base;
 65 
 66         if (!str || !*str)
 67                 return;
 68         while (d) {
 69                 if (!strcmp(str,d->name)) {
 70                         if (ints[0] > 0)
 71                                 d->irq=ints[1];
 72                         if (ints[0] > 1)
 73                                 d->base_addr=ints[2];
 74                         if (ints[0] > 2)
 75                                 d->mem_start=ints[3];
 76                         if (ints[0] > 3)
 77                                 d->mem_end=ints[4];
 78                         break;
 79                 }
 80                 d=d->next;
 81         }
 82 }
 83 
 84 /* Display the contents of the Ethernet MAC header. */
 85 void
 86 eth_dump(struct ethhdr *eth)
 87 {
 88   if (inet_debug != DBG_ETH) return;
 89 
 90   printk("eth: SRC = %s ", eth_print(eth->h_source));
 91   printk("DST = %s ", eth_print(eth->h_dest));
 92   printk("TYPE = %04X\n", ntohs(eth->h_proto));
 93 }
 94 
 95 
 96 /* Create the Ethernet MAC header. */
 97 int
 98 eth_header(unsigned char *buff, struct device *dev, unsigned short type,
 99            unsigned long daddr, unsigned long saddr, unsigned len)
100 {
101   struct ethhdr *eth;
102 
103   DPRINTF((DBG_DEV, "ETH: header(%s, ", in_ntoa(saddr)));
104   DPRINTF((DBG_DEV, "%s, 0x%X)\n", in_ntoa(daddr), type));
105 
106   /* Fill in the basic Ethernet MAC header. */
107   eth = (struct ethhdr *) buff;
108   eth->h_proto = htons(type);
109 
110   /* We don't ARP for the LOOPBACK device... */
111   if (dev->flags & IFF_LOOPBACK) {
112         DPRINTF((DBG_DEV, "ETH: No header for loopback\n"));
113         memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
114         memset(eth->h_dest, 0, dev->addr_len);
115         return(dev->hard_header_len);
116   }
117 
118   /* Check if we can use the MAC BROADCAST address. */
119   if (chk_addr(daddr) == IS_BROADCAST) {
120         DPRINTF((DBG_DEV, "ETH: Using MAC Broadcast\n"));
121         memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
122         memcpy(eth->h_dest, dev->broadcast, dev->addr_len);
123         return(dev->hard_header_len);
124   }
125   cli();
126   memcpy(eth->h_source, &saddr, 4);
127   /* No. Ask ARP to resolve the Ethernet address. */
128   if (arp_find(eth->h_dest, daddr, dev, dev->pa_addr)) 
129   {
130         sti();
131         if(type!=ETH_P_IP)
132                 printk("Erk: protocol %X got into an arp request state!\n",type);
133         return(-dev->hard_header_len);
134   } 
135   else
136   {
137         memcpy(eth->h_source,dev->dev_addr,dev->addr_len);      /* This was missing causing chaos if the
138                                                                    header built correctly! */
139         sti();
140         return(dev->hard_header_len);
141   }
142 }
143 
144 
145 /* Rebuild the Ethernet MAC header. */
146 int
147 eth_rebuild_header(void *buff, struct device *dev)
148 {
149   struct ethhdr *eth;
150   unsigned long src, dst;
151 
152   DPRINTF((DBG_DEV, "ETH: Using MAC Broadcast\n"));
153   eth = (struct ethhdr *) buff;
154   src = *(unsigned long *) eth->h_source;
155   dst = *(unsigned long *) eth->h_dest;
156   DPRINTF((DBG_DEV, "ETH: RebuildHeader: SRC=%s ", in_ntoa(src)));
157   DPRINTF((DBG_DEV, "DST=%s\n", in_ntoa(dst)));
158   if(eth->h_proto!=htons(ETH_P_ARP))    /* This ntohs kind of helps a bit! */
159           if (arp_find(eth->h_dest, dst, dev, dev->pa_addr /* src */)) return(1);
160   memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
161   return(0);
162 }
163 
164 
165 /* Add an ARP entry for a host on this interface. */
166 void
167 eth_add_arp(unsigned long addr, struct sk_buff *skb, struct device *dev)
168 {
169   struct ethhdr *eth;
170 
171   eth = (struct ethhdr *) skb->data;
172   arp_add(addr, eth->h_source, dev);
173 }
174 
175 
176 /* Determine the packet's protocol ID. */
177 unsigned short
178 eth_type_trans(struct sk_buff *skb, struct device *dev)
179 {
180   struct ethhdr *eth;
181 
182   eth = (struct ethhdr *) skb->data;
183 
184   if(ntohs(eth->h_proto)<1536)
185         return(htons(ETH_P_802_3));
186   return(eth->h_proto);
187 }
188