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*/
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 *
30 * This program is free software; you can redistribute it and/or
31 * modify it under the terms of the GNU General Public License
32 * as published by the Free Software Foundation; either version
33 * 2 of the License, or (at your option) any later version.
34 */
35 #include <asm/segment.h>
36 #include <asm/system.h>
37 #include <linux/types.h>
38 #include <linux/kernel.h>
39 #include <linux/sched.h>
40 #include <linux/string.h>
41 #include <linux/mm.h>
42 #include <linux/socket.h>
43 #include <linux/in.h>
44 #include <linux/inet.h>
45 #include <linux/netdevice.h>
46 #include <linux/etherdevice.h>
47 #include <linux/skbuff.h>
48 #include <linux/errno.h>
49 #include <linux/config.h>
50 #include <net/arp.h>
51 #include <net/sock.h>
52 #include <asm/checksum.h>
53
54 void eth_setup(char *str, int *ints)
/* ![[next]](../icons/right.png)
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*/
55 {
56 struct device *d = dev_base;
57
58 if (!str || !*str)
59 return;
60 while (d)
61 {
62 if (!strcmp(str,d->name))
63 {
64 if (ints[0] > 0)
65 d->irq=ints[1];
66 if (ints[0] > 1)
67 d->base_addr=ints[2];
68 if (ints[0] > 2)
69 d->mem_start=ints[3];
70 if (ints[0] > 3)
71 d->mem_end=ints[4];
72 break;
73 }
74 d=d->next;
75 }
76 }
77
78
79 /*
80 * Create the Ethernet MAC header for an arbitrary protocol layer
81 *
82 * saddr=NULL means use device source address
83 * daddr=NULL means leave destination address (eg unresolved arp)
84 */
85
86 int eth_header(struct sk_buff *skb, struct device *dev, unsigned short type,
/* ![[previous]](../icons/left.png)
*/
87 void *daddr, void *saddr, unsigned len)
88 {
89 struct ethhdr *eth = (struct ethhdr *)skb_push(skb,14);
90
91 /*
92 * Set the protocol type. For a packet of type ETH_P_802_3 we put the length
93 * in here instead. It is up to the 802.2 layer to carry protocol information.
94 */
95
96 if(type!=ETH_P_802_3)
97 eth->h_proto = htons(type);
98 else
99 eth->h_proto = htons(len);
100
101 /*
102 * Set the source hardware address.
103 */
104
105 if(saddr)
106 memcpy(eth->h_source,saddr,dev->addr_len);
107 else
108 memcpy(eth->h_source,dev->dev_addr,dev->addr_len);
109
110 /*
111 * Anyway, the loopback-device should never use this function...
112 */
113
114 if (dev->flags & IFF_LOOPBACK)
115 {
116 memset(eth->h_dest, 0, dev->addr_len);
117 return(dev->hard_header_len);
118 }
119
120 if(daddr)
121 {
122 memcpy(eth->h_dest,daddr,dev->addr_len);
123 return dev->hard_header_len;
124 }
125
126 return -dev->hard_header_len;
127 }
128
129
130 /*
131 * Rebuild the Ethernet MAC header. This is called after an ARP
132 * (or in future other address resolution) has completed on this
133 * sk_buff. We now let ARP fill in the other fields.
134 */
135
136 int eth_rebuild_header(void *buff, struct device *dev, unsigned long dst,
/* */
137 struct sk_buff *skb)
138 {
139 struct ethhdr *eth = (struct ethhdr *)buff;
140
141 /*
142 * Only ARP/IP is currently supported
143 */
144
145 if(eth->h_proto != htons(ETH_P_IP))
146 {
147 printk("eth_rebuild_header: Don't know how to resolve type %d addresses?\n",(int)eth->h_proto);
148 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
149 return 0;
150 }
151
152 /*
153 * Try and get ARP to resolve the header.
154 */
155 #ifdef CONFIG_INET
156 return arp_find(eth->h_dest, dst, dev, dev->pa_addr, skb)? 1 : 0;
157 #else
158 return 0;
159 #endif
160 }
161
162
163 /*
164 * Determine the packet's protocol ID. The rule here is that we
165 * assume 802.3 if the type field is short enough to be a length.
166 * This is normal practice and works for any 'now in use' protocol.
167 */
168
169 unsigned short eth_type_trans(struct sk_buff *skb, struct device *dev)
/* */
170 {
171 struct ethhdr *eth;
172 unsigned char *rawp;
173
174 skb->mac.raw=skb->data;
175 skb_pull(skb,14);
176 eth= skb->mac.ethernet;
177
178 if(*eth->h_dest&1)
179 {
180 if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
181 skb->pkt_type=PACKET_BROADCAST;
182 else
183 skb->pkt_type=PACKET_MULTICAST;
184 }
185
186 else if(dev->flags&IFF_PROMISC)
187 {
188 if(memcmp(eth->h_dest,dev->dev_addr, ETH_ALEN))
189 skb->pkt_type=PACKET_OTHERHOST;
190 }
191
192 if (ntohs(eth->h_proto) >= 1536)
193 return eth->h_proto;
194
195 rawp = skb->data;
196
197 /*
198 * This is a magic hack to spot IPX packets. Older Novell breaks
199 * the protocol design and runs IPX over 802.3 without an 802.2 LLC
200 * layer. We look for FFFF which isnt a used 802.2 SSAP/DSAP. This
201 * won't work for fault tolerant netware but does for the rest.
202 */
203 if (*(unsigned short *)rawp == 0xFFFF)
204 return htons(ETH_P_802_3);
205
206 /*
207 * Real 802.2 LLC
208 */
209 return htons(ETH_P_802_2);
210 }
211
212 /*
213 * Header caching for ethernet. Try to find and cache a header to avoid arp overhead.
214 */
215
216 void eth_header_cache(struct device *dev, struct sock *sk, unsigned long saddr, unsigned long daddr)
/* */
217 {
218 int v=arp_find_cache(sk->ip_hcache_data, daddr, dev);
219 if(v!=1)
220 sk->ip_hcache_state=0; /* Try when arp resolves */
221 else
222 {
223 memcpy(sk->ip_hcache_data+6, dev->dev_addr, ETH_ALEN);
224 sk->ip_hcache_data[12]=ETH_P_IP>>8;
225 sk->ip_hcache_data[13]=ETH_P_IP&0xFF;
226 sk->ip_hcache_state=1;
227 sk->ip_hcache_stamp=arp_cache_stamp;
228 sk->ip_hcache_ver=&arp_cache_stamp;
229 }
230 }
231
232 /*
233 * Copy from an ethernet device memory space to an sk_buff while checksumming if IP
234 */
235
236 void eth_copy_and_sum(struct sk_buff *dest,unsigned char *src, int length, int base)
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*/
237 {
238 struct ethhdr *eth=(struct ethhdr *)dest->data;
239 memcpy(dest->data,src,34); /* ethernet is always >= 60 */
240 length-=34;
241 if(eth->h_proto!=htons(ETH_P_IP))
242 {
243 memcpy(dest->data+34,src+34,length);
244 return;
245 }
246 dest->csum=csum_partial_copy(src+34,dest->data+34,length,base);
247 dest->ip_summed=1;
248 }
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*/