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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 * 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 <asm/segment.h>
40 #include <asm/system.h>
41 #include <linux/types.h>
42 #include <linux/kernel.h>
43 #include <linux/sched.h>
44 #include <linux/string.h>
45 #include <linux/mm.h>
46 #include <linux/socket.h>
47 #include <linux/in.h>
48 #include <linux/inet.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 <net/arp.h>
55 #include <net/sock.h>
56 #include <asm/checksum.h>
57
58 void eth_setup(char *str, int *ints)
/* ![[next]](../icons/right.png)
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*/
59 {
60 struct device *d = dev_base;
61
62 if (!str || !*str)
63 return;
64 while (d)
65 {
66 if (!strcmp(str,d->name))
67 {
68 if (ints[0] > 0)
69 d->irq=ints[1];
70 if (ints[0] > 1)
71 d->base_addr=ints[2];
72 if (ints[0] > 2)
73 d->mem_start=ints[3];
74 if (ints[0] > 3)
75 d->mem_end=ints[4];
76 break;
77 }
78 d=d->next;
79 }
80 }
81
82
83 /*
84 * Create the Ethernet MAC header for an arbitrary protocol layer
85 *
86 * saddr=NULL means use device source address
87 * daddr=NULL means leave destination address (eg unresolved arp)
88 */
89
90 int eth_header(struct sk_buff *skb, struct device *dev, unsigned short type,
/* ![[previous]](../icons/left.png)
*/
91 void *daddr, void *saddr, unsigned len)
92 {
93 struct ethhdr *eth = (struct ethhdr *)skb_push(skb,ETH_HLEN);
94
95 /*
96 * Set the protocol type. For a packet of type ETH_P_802_3 we put the length
97 * in here instead. It is up to the 802.2 layer to carry protocol information.
98 */
99
100 if(type!=ETH_P_802_3)
101 eth->h_proto = htons(type);
102 else
103 eth->h_proto = htons(len);
104
105 /*
106 * Set the source hardware address.
107 */
108
109 if(saddr)
110 memcpy(eth->h_source,saddr,dev->addr_len);
111 else
112 memcpy(eth->h_source,dev->dev_addr,dev->addr_len);
113
114 /*
115 * Anyway, the loopback-device should never use this function...
116 */
117
118 if (dev->flags & IFF_LOOPBACK)
119 {
120 memset(eth->h_dest, 0, dev->addr_len);
121 return(dev->hard_header_len);
122 }
123
124 if(daddr)
125 {
126 memcpy(eth->h_dest,daddr,dev->addr_len);
127 return dev->hard_header_len;
128 }
129
130 return -dev->hard_header_len;
131 }
132
133
134 /*
135 * Rebuild the Ethernet MAC header. This is called after an ARP
136 * (or in future other address resolution) has completed on this
137 * sk_buff. We now let ARP fill in the other fields.
138 */
139
140 int eth_rebuild_header(void *buff, struct device *dev, unsigned long dst,
/* */
141 struct sk_buff *skb)
142 {
143 struct ethhdr *eth = (struct ethhdr *)buff;
144
145 /*
146 * Only ARP/IP is currently supported
147 */
148
149 if(eth->h_proto != htons(ETH_P_IP))
150 {
151 printk(KERN_DEBUG "%s: unable to resolve type %X addresses.\n",dev->name,(int)eth->h_proto);
152 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
153 return 0;
154 }
155
156 /*
157 * Try to get ARP to resolve the header.
158 */
159 #ifdef CONFIG_INET
160 return arp_find(eth->h_dest, dst, dev, dev->pa_addr, skb)? 1 : 0;
161 #else
162 return 0;
163 #endif
164 }
165
166
167 /*
168 * Determine the packet's protocol ID. The rule here is that we
169 * assume 802.3 if the type field is short enough to be a length.
170 * This is normal practice and works for any 'now in use' protocol.
171 */
172
173 unsigned short eth_type_trans(struct sk_buff *skb, struct device *dev)
/* */
174 {
175 struct ethhdr *eth;
176 unsigned char *rawp;
177
178 skb->mac.raw=skb->data;
179 skb_pull(skb,dev->hard_header_len);
180 eth= skb->mac.ethernet;
181
182 if(*eth->h_dest&1)
183 {
184 if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
185 skb->pkt_type=PACKET_BROADCAST;
186 else
187 skb->pkt_type=PACKET_MULTICAST;
188 }
189
190 /*
191 * This ALLMULTI check should be redundant by 1.4
192 * so don't forget to remove it.
193 */
194
195 else if(dev->flags&(IFF_PROMISC|IFF_ALLMULTI))
196 {
197 if(memcmp(eth->h_dest,dev->dev_addr, ETH_ALEN))
198 skb->pkt_type=PACKET_OTHERHOST;
199 }
200
201 if (ntohs(eth->h_proto) >= 1536)
202 return eth->h_proto;
203
204 rawp = skb->data;
205
206 /*
207 * This is a magic hack to spot IPX packets. Older Novell breaks
208 * the protocol design and runs IPX over 802.3 without an 802.2 LLC
209 * layer. We look for FFFF which isn't a used 802.2 SSAP/DSAP. This
210 * won't work for fault tolerant netware but does for the rest.
211 */
212 if (*(unsigned short *)rawp == 0xFFFF)
213 return htons(ETH_P_802_3);
214
215 /*
216 * Real 802.2 LLC
217 */
218 return htons(ETH_P_802_2);
219 }
220
221 /*
222 * Upper level calls this function to bind hardware header cache entry.
223 * If the call is successful, then corresponding Address Resolution Protocol
224 * (maybe, not ARP) takes responsibility for updating cache content.
225 */
226
227 void eth_header_cache_bind(struct hh_cache ** hhp, struct device *dev,
/* */
228 unsigned short htype, __u32 daddr)
229 {
230 struct hh_cache *hh;
231
232 if (htype != ETH_P_IP)
233 {
234 printk("eth_header_cache_bind: %04x cache is not implemented\n", htype);
235 return;
236 }
237 if (arp_bind_cache(hhp, dev, htype, daddr))
238 return;
239 if ((hh=*hhp) != NULL)
240 {
241 memcpy(hh->hh_data+6, dev->dev_addr, ETH_ALEN);
242 hh->hh_data[12] = htype>>8;
243 hh->hh_data[13] = htype&0xFF;
244 }
245 }
246
247 /*
248 * Called by Address Resolution module to notify changes in address.
249 */
250
251 void eth_header_cache_update(struct hh_cache *hh, struct device *dev, unsigned char * haddr)
/* */
252 {
253 if (hh->hh_type != ETH_P_IP)
254 {
255 printk("eth_header_cache_update: %04x cache is not implemented\n", hh->hh_type);
256 return;
257 }
258 memcpy(hh->hh_data, haddr, ETH_ALEN);
259 hh->hh_uptodate = 1;
260 }
261
262 /*
263 * Copy from an ethernet device memory space to an sk_buff while checksumming if IP
264 */
265
266 void eth_copy_and_sum(struct sk_buff *dest, unsigned char *src, int length, int base)
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*/
267 {
268 #ifdef CONFIG_IP_ROUTER
269 memcpy(dest->data,src,length);
270 #else
271 struct ethhdr *eth;
272 struct iphdr *iph;
273 int ip_length;
274
275 IS_SKB(dest);
276 eth=(struct ethhdr *)dest->data;
277 if(eth->h_proto!=htons(ETH_P_IP))
278 {
279 memcpy(dest->data,src,length);
280 return;
281 }
282 /*
283 * We have to watch for padded packets. The csum doesn't include the
284 * padding, and there is no point in copying the padding anyway.
285 * We have to use the smaller of length and ip_length because it
286 * can happen that ip_length > length.
287 */
288 memcpy(dest->data,src,sizeof(struct iphdr)+ETH_HLEN); /* ethernet is always >= 34 */
289 length -= sizeof(struct iphdr) + ETH_HLEN;
290 iph=(struct iphdr*)(src+ETH_HLEN);
291 ip_length = ntohs(iph->tot_len) - sizeof(struct iphdr);
292
293 /* Also watch out for bogons - min IP size is 8 (rfc-1042) */
294 if ((ip_length <= length) && (ip_length > 7))
295 length=ip_length;
296
297 dest->csum=csum_partial_copy(src+sizeof(struct iphdr)+ETH_HLEN,dest->data+sizeof(struct iphdr)+ETH_HLEN,length,base);
298 dest->ip_summed=1;
299 #endif
300 }
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*/