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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 *
29 * This program is free software; you can redistribute it and/or
30 * modify it under the terms of the GNU General Public License
31 * as published by the Free Software Foundation; either version
32 * 2 of the License, or (at your option) any later version.
33 */
34 #include <asm/segment.h>
35 #include <asm/system.h>
36 #include <linux/types.h>
37 #include <linux/kernel.h>
38 #include <linux/sched.h>
39 #include <linux/string.h>
40 #include <linux/mm.h>
41 #include <linux/socket.h>
42 #include <linux/in.h>
43 #include <linux/inet.h>
44 #include <linux/netdevice.h>
45 #include <linux/etherdevice.h>
46 #include <linux/skbuff.h>
47 #include <linux/errno.h>
48 #include <linux/config.h>
49 #include <net/arp.h>
50 #include <net/sock.h>
51
52 void eth_setup(char *str, int *ints)
/* ![[next]](../icons/right.png)
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*/
53 {
54 struct device *d = dev_base;
55
56 if (!str || !*str)
57 return;
58 while (d)
59 {
60 if (!strcmp(str,d->name))
61 {
62 if (ints[0] > 0)
63 d->irq=ints[1];
64 if (ints[0] > 1)
65 d->base_addr=ints[2];
66 if (ints[0] > 2)
67 d->mem_start=ints[3];
68 if (ints[0] > 3)
69 d->mem_end=ints[4];
70 break;
71 }
72 d=d->next;
73 }
74 }
75
76
77 /*
78 * Create the Ethernet MAC header for an arbitrary protocol layer
79 *
80 * saddr=NULL means use device source address
81 * daddr=NULL means leave destination address (eg unresolved arp)
82 */
83
84 int eth_header(unsigned char *buff, struct device *dev, unsigned short type,
/* ![[previous]](../icons/left.png)
*/
85 void *daddr, void *saddr, unsigned len,
86 struct sk_buff *skb)
87 {
88 struct ethhdr *eth = (struct ethhdr *)buff;
89
90 /*
91 * Set the protocol type. For a packet of type ETH_P_802_3 we put the length
92 * in here instead. It is up to the 802.2 layer to carry protocol information.
93 */
94
95 if(type!=ETH_P_802_3)
96 eth->h_proto = htons(type);
97 else
98 eth->h_proto = htons(len);
99
100 /*
101 * Set the source hardware address.
102 */
103
104 if(saddr)
105 memcpy(eth->h_source,saddr,dev->addr_len);
106 else
107 memcpy(eth->h_source,dev->dev_addr,dev->addr_len);
108
109 /*
110 * Anyway, the loopback-device should never use this function...
111 */
112
113 if (dev->flags & IFF_LOOPBACK)
114 {
115 memset(eth->h_dest, 0, dev->addr_len);
116 return(dev->hard_header_len);
117 }
118
119 if(daddr)
120 {
121 memcpy(eth->h_dest,daddr,dev->addr_len);
122 return dev->hard_header_len;
123 }
124
125 return -dev->hard_header_len;
126 }
127
128
129 /*
130 * Rebuild the Ethernet MAC header. This is called after an ARP
131 * (or in future other address resolution) has completed on this
132 * sk_buff. We now let ARP fill in the other fields.
133 */
134
135 int eth_rebuild_header(void *buff, struct device *dev, unsigned long dst,
/* */
136 struct sk_buff *skb)
137 {
138 struct ethhdr *eth = (struct ethhdr *)buff;
139
140 /*
141 * Only ARP/IP is currently supported
142 */
143
144 if(eth->h_proto != htons(ETH_P_IP))
145 {
146 printk("eth_rebuild_header: Don't know how to resolve type %d addresses?\n",(int)eth->h_proto);
147 memcpy(eth->h_source, dev->dev_addr, dev->addr_len);
148 return 0;
149 }
150
151 /*
152 * Try and get ARP to resolve the header.
153 */
154 #ifdef CONFIG_INET
155 return arp_find(eth->h_dest, dst, dev, dev->pa_addr, skb)? 1 : 0;
156 #else
157 return 0;
158 #endif
159 }
160
161
162 /*
163 * Determine the packet's protocol ID. The rule here is that we
164 * assume 802.3 if the type field is short enough to be a length.
165 * This is normal practice and works for any 'now in use' protocol.
166 */
167
168 unsigned short eth_type_trans(struct sk_buff *skb, struct device *dev)
/* */
169 {
170 struct ethhdr *eth = (struct ethhdr *) skb->data;
171 unsigned char *rawp;
172
173 if(*eth->h_dest&1)
174 {
175 if(memcmp(eth->h_dest,dev->broadcast, ETH_ALEN)==0)
176 skb->pkt_type=PACKET_BROADCAST;
177 else
178 skb->pkt_type=PACKET_MULTICAST;
179 }
180
181 else if(dev->flags&IFF_PROMISC)
182 {
183 if(memcmp(eth->h_dest,dev->dev_addr, ETH_ALEN))
184 skb->pkt_type=PACKET_OTHERHOST;
185 }
186
187 if (ntohs(eth->h_proto) >= 1536)
188 return eth->h_proto;
189
190 rawp = (unsigned char *)(eth + 1);
191
192 if (*(unsigned short *)rawp == 0xFFFF)
193 return htons(ETH_P_802_3);
194
195 return htons(ETH_P_802_2);
196 }
197
198 /*
199 * Header caching for ethernet. Try to find and cache a header to avoid arp overhead.
200 */
201
202 void eth_header_cache(struct device *dev, struct sock *sk, unsigned long saddr, unsigned long daddr)
/* ![[last]](../icons/n_last.png)
*/
203 {
204 int v=arp_find_cache(sk->ip_hcache_data, daddr, dev);
205 if(v!=1)
206 sk->ip_hcache_state=0; /* Try when arp resolves */
207 else
208 {
209 memcpy(sk->ip_hcache_data+6, dev->dev_addr, ETH_ALEN);
210 sk->ip_hcache_data[12]=ETH_P_IP>>8;
211 sk->ip_hcache_data[13]=ETH_P_IP&0xFF;
212 sk->ip_hcache_state=1;
213 sk->ip_hcache_stamp=arp_cache_stamp;
214 sk->ip_hcache_ver=&arp_cache_stamp;
215 }
216 }
217
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*/