blob: 1053821ddf933c922f01e5e8a9733046b0e64676 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * SNAP data link layer. Derived from 802.2
3 *
4 * Alan Cox <Alan.Cox@linux.org>,
5 * from the 802.2 layer by Greg Page.
6 * Merged in additions from Greg Page's psnap.c.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License
10 * as published by the Free Software Foundation; either version
11 * 2 of the License, or (at your option) any later version.
12 */
13
14#include <linux/module.h>
15#include <linux/netdevice.h>
16#include <linux/skbuff.h>
17#include <net/datalink.h>
18#include <net/llc.h>
19#include <net/psnap.h>
20#include <linux/mm.h>
21#include <linux/in.h>
22#include <linux/init.h>
23
24static LIST_HEAD(snap_list);
25static DEFINE_SPINLOCK(snap_lock);
26static struct llc_sap *snap_sap;
27
28/*
29 * Find a snap client by matching the 5 bytes.
30 */
31static struct datalink_proto *find_snap_client(unsigned char *desc)
32{
33 struct list_head *entry;
34 struct datalink_proto *proto = NULL, *p;
35
36 list_for_each_rcu(entry, &snap_list) {
37 p = list_entry(entry, struct datalink_proto, node);
38 if (!memcmp(p->type, desc, 5)) {
39 proto = p;
40 break;
41 }
42 }
43 return proto;
44}
45
46/*
47 * A SNAP packet has arrived
48 */
49static int snap_rcv(struct sk_buff *skb, struct net_device *dev,
50 struct packet_type *pt)
51{
52 int rc = 1;
53 struct datalink_proto *proto;
54 static struct packet_type snap_packet_type = {
55 .type = __constant_htons(ETH_P_SNAP),
56 };
57
58 rcu_read_lock();
59 proto = find_snap_client(skb->h.raw);
60 if (proto) {
61 /* Pass the frame on. */
62 skb->h.raw += 5;
63 skb_pull(skb, 5);
64 rc = proto->rcvfunc(skb, dev, &snap_packet_type);
65 } else {
66 skb->sk = NULL;
67 kfree_skb(skb);
68 rc = 1;
69 }
70
71 rcu_read_unlock();
72 return rc;
73}
74
75/*
76 * Put a SNAP header on a frame and pass to 802.2
77 */
78static int snap_request(struct datalink_proto *dl,
79 struct sk_buff *skb, u8 *dest)
80{
81 memcpy(skb_push(skb, 5), dl->type, 5);
82 llc_build_and_send_ui_pkt(snap_sap, skb, dest, snap_sap->laddr.lsap);
83 return 0;
84}
85
86/*
87 * Set up the SNAP layer
88 */
89EXPORT_SYMBOL(register_snap_client);
90EXPORT_SYMBOL(unregister_snap_client);
91
92static char snap_err_msg[] __initdata =
93 KERN_CRIT "SNAP - unable to register with 802.2\n";
94
95static int __init snap_init(void)
96{
97 snap_sap = llc_sap_open(0xAA, snap_rcv);
98
99 if (!snap_sap)
100 printk(snap_err_msg);
101
102 return 0;
103}
104
105module_init(snap_init);
106
107static void __exit snap_exit(void)
108{
109 llc_sap_close(snap_sap);
110}
111
112module_exit(snap_exit);
113
114
115/*
116 * Register SNAP clients. We don't yet use this for IP.
117 */
118struct datalink_proto *register_snap_client(unsigned char *desc,
119 int (*rcvfunc)(struct sk_buff *,
120 struct net_device *,
121 struct packet_type *))
122{
123 struct datalink_proto *proto = NULL;
124
125 spin_lock_bh(&snap_lock);
126
127 if (find_snap_client(desc))
128 goto out;
129
130 proto = kmalloc(sizeof(*proto), GFP_ATOMIC);
131 if (proto) {
132 memcpy(proto->type, desc,5);
133 proto->rcvfunc = rcvfunc;
134 proto->header_length = 5 + 3; /* snap + 802.2 */
135 proto->request = snap_request;
136 list_add_rcu(&proto->node, &snap_list);
137 }
138out:
139 spin_unlock_bh(&snap_lock);
140
141 synchronize_net();
142 return proto;
143}
144
145/*
146 * Unregister SNAP clients. Protocols no longer want to play with us ...
147 */
148void unregister_snap_client(struct datalink_proto *proto)
149{
150 spin_lock_bh(&snap_lock);
151 list_del_rcu(&proto->node);
152 spin_unlock_bh(&snap_lock);
153
154 synchronize_net();
155
156 kfree(proto);
157}
158
159MODULE_LICENSE("GPL");