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 * Andrew Morton : 26Feb01: kill ether_setup() - use netdev_boot_setup().
34 *
35 * This program is free software; you can redistribute it and/or
36 * modify it under the terms of the GNU General Public License
37 * as published by the Free Software Foundation; either version
38 * 2 of the License, or (at your option) any later version.
39 */
40 #include <linux/types.h>
41 #include <linux/kernel.h>
42 #include <linux/sched.h>
43 #include <linux/string.h>
44 #include <linux/mm.h>
45 #include <linux/socket.h>
46 #include <linux/in.h>
47 #include <linux/inet.h>
48 #include <linux/ip.h>
49 #include <linux/netdevice.h>
50 #include <linux/etherdevice.h>
51 #include <linux/skbuff.h>
52 #include <linux/errno.h>
53 #include <linux/config.h>
54 #include <linux/init.h>
55 #include <net/dst.h>
56 #include <net/arp.h>
57 #include <net/sock.h>
58 #include <net/ipv6.h>
59 #include <net/ip.h>
60 #include <asm/uaccess.h>
61 #include <asm/system.h>
62 #include <asm/checksum.h>
63
64 extern int __init netdev_boot_setup(char *str);
65
66 __setup("ether=", netdev_boot_setup);
67
68 /*
69 * Create the Ethernet MAC header for an arbitrary protocol layer
70 *
71 * saddr=NULL means use device source address
72 * daddr=NULL means leave destination address (eg unresolved arp)
73 */
74
eth_header(struct sk_buff * skb,struct net_device * dev,unsigned short type,void * daddr,void * saddr,unsigned len)75 int eth_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
76 void *daddr, void *saddr, unsigned len)
77 {
78 struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN);
79
80 /*
81 * Set the protocol type. For a packet of type ETH_P_802_3 we put the length
82 * in here instead. It is up to the 802.2 layer to carry protocol information.
83 */
84
85 if(type!=ETH_P_802_3)
86 eth->h_proto = htons(type);
87 else
88 eth->h_proto = htons(len);
89
90 /*
91 * Set the source hardware address.
92 */
93
94 if(saddr)
95 memcpy(eth->h_source,saddr,dev->addr_len);
96 else
97 memcpy(eth->h_source,dev->dev_addr,dev->addr_len);
98
99 if(daddr)
100 {
101 memcpy(eth->h_dest,daddr,dev->addr_len);
102 return dev->hard_header_len;
103 }
104
105 /*
106 * Anyway, the loopback-device should never use this function...
107 */
108
109 if (dev->flags & (IFF_LOOPBACK|IFF_NOARP))
110 {
111 memset(eth->h_dest, 0, dev->addr_len);
112 return(dev->hard_header_len);
113 }
114
115 return -dev->hard_header_len;
116 }
117
118
119 /*
120 * Rebuild the Ethernet MAC header. This is called after an ARP
121 * (or in future other address resolution) has completed on this
122 * sk_buff. We now let ARP fill in the other fields.
123 *
124 * This routine CANNOT use cached dst->neigh!
125 * Really, it is used only when dst->neigh is wrong.
126 */
127
eth_rebuild_header(struct sk_buff * skb)128 int eth_rebuild_header(struct sk_buff *skb)
129 {
130 struct ethhdr *eth = (struct ethhdr *)skb->data;
131 struct net_device *dev = skb->dev;
132
133 switch (eth->h_proto)
134 {
135 #ifdef CONFIG_INET
136 case __constant_htons(ETH_P_IP):
137 return arp_find(eth->h_dest, skb);
138 #endif
139 default:
140 printk(KERN_DEBUG
141 "%s: unable to resolve type %X addresses.\n",
142 dev->name, (int)eth->h_proto);
143
144 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
145 break;
146 }
147
148 return 0;
149 }
150
151
152 /*
153 * Determine the packet's protocol ID. The rule here is that we
154 * assume 802.3 if the type field is short enough to be a length.
155 * This is normal practice and works for any 'now in use' protocol.
156 */
157
eth_type_trans(struct sk_buff * skb,struct net_device * dev)158 unsigned short eth_type_trans(struct sk_buff *skb, struct net_device *dev)
159 {
160 struct ethhdr *eth;
161 unsigned char *rawp;
162
163 skb->mac.raw=skb->data;
164 skb_pull(skb,dev->hard_header_len);
165 eth= skb->mac.ethernet;
166
167 if(*eth->h_dest&1)
168 {
169 if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
170 skb->pkt_type=PACKET_BROADCAST;
171 else
172 skb->pkt_type=PACKET_MULTICAST;
173 }
174
175 /*
176 * This ALLMULTI check should be redundant by 1.4
177 * so don't forget to remove it.
178 *
179 * Seems, you forgot to remove it. All silly devices
180 * seems to set IFF_PROMISC.
181 */
182
183 else if(1 /*dev->flags&IFF_PROMISC*/)
184 {
185 if(memcmp(eth->h_dest,dev->dev_addr, ETH_ALEN))
186 skb->pkt_type=PACKET_OTHERHOST;
187 }
188
189 if (ntohs(eth->h_proto) >= 1536)
190 return eth->h_proto;
191
192 rawp = skb->data;
193
194 /*
195 * This is a magic hack to spot IPX packets. Older Novell breaks
196 * the protocol design and runs IPX over 802.3 without an 802.2 LLC
197 * layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
198 * won't work for fault tolerant netware but does for the rest.
199 */
200 if (*(unsigned short *)rawp == 0xFFFF)
201 return htons(ETH_P_802_3);
202
203 /*
204 * Real 802.2 LLC
205 */
206 return htons(ETH_P_802_2);
207 }
208
eth_header_parse(struct sk_buff * skb,unsigned char * haddr)209 int eth_header_parse(struct sk_buff *skb, unsigned char *haddr)
210 {
211 struct ethhdr *eth = skb->mac.ethernet;
212 memcpy(haddr, eth->h_source, ETH_ALEN);
213 return ETH_ALEN;
214 }
215
eth_header_cache(struct neighbour * neigh,struct hh_cache * hh)216 int eth_header_cache(struct neighbour *neigh, struct hh_cache *hh)
217 {
218 unsigned short type = hh->hh_type;
219 struct ethhdr *eth;
220 struct net_device *dev = neigh->dev;
221
222 eth = (struct ethhdr*)
223 (((u8*)hh->hh_data) + (HH_DATA_OFF(sizeof(*eth))));
224
225 if (type == __constant_htons(ETH_P_802_3))
226 return -1;
227
228 eth->h_proto = type;
229 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
230 memcpy(eth->h_dest, neigh->ha, dev->addr_len);
231 hh->hh_len = ETH_HLEN;
232 return 0;
233 }
234
235 /*
236 * Called by Address Resolution module to notify changes in address.
237 */
238
eth_header_cache_update(struct hh_cache * hh,struct net_device * dev,unsigned char * haddr)239 void eth_header_cache_update(struct hh_cache *hh, struct net_device *dev, unsigned char * haddr)
240 {
241 memcpy(((u8*)hh->hh_data) + HH_DATA_OFF(sizeof(struct ethhdr)),
242 haddr, dev->addr_len);
243 }
244