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1da177e4 LT |
1 | /* |
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 | ||
24 | static LIST_HEAD(snap_list); | |
25 | static DEFINE_SPINLOCK(snap_lock); | |
26 | static struct llc_sap *snap_sap; | |
27 | ||
28 | /* | |
29 | * Find a snap client by matching the 5 bytes. | |
30 | */ | |
31 | static 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 | */ | |
49 | static int snap_rcv(struct sk_buff *skb, struct net_device *dev, | |
f2ccd8fa | 50 | struct packet_type *pt, struct net_device *orig_dev) |
1da177e4 LT |
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); | |
f2ccd8fa | 64 | rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev); |
1da177e4 LT |
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 | */ | |
78 | static 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 | */ | |
89 | EXPORT_SYMBOL(register_snap_client); | |
90 | EXPORT_SYMBOL(unregister_snap_client); | |
91 | ||
92 | static char snap_err_msg[] __initdata = | |
93 | KERN_CRIT "SNAP - unable to register with 802.2\n"; | |
94 | ||
95 | static 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 | ||
105 | module_init(snap_init); | |
106 | ||
107 | static void __exit snap_exit(void) | |
108 | { | |
6e2144b7 | 109 | llc_sap_put(snap_sap); |
1da177e4 LT |
110 | } |
111 | ||
112 | module_exit(snap_exit); | |
113 | ||
114 | ||
115 | /* | |
116 | * Register SNAP clients. We don't yet use this for IP. | |
117 | */ | |
118 | struct datalink_proto *register_snap_client(unsigned char *desc, | |
119 | int (*rcvfunc)(struct sk_buff *, | |
120 | struct net_device *, | |
f2ccd8fa DM |
121 | struct packet_type *, |
122 | struct net_device *)) | |
1da177e4 LT |
123 | { |
124 | struct datalink_proto *proto = NULL; | |
125 | ||
126 | spin_lock_bh(&snap_lock); | |
127 | ||
128 | if (find_snap_client(desc)) | |
129 | goto out; | |
130 | ||
131 | proto = kmalloc(sizeof(*proto), GFP_ATOMIC); | |
132 | if (proto) { | |
133 | memcpy(proto->type, desc,5); | |
134 | proto->rcvfunc = rcvfunc; | |
135 | proto->header_length = 5 + 3; /* snap + 802.2 */ | |
136 | proto->request = snap_request; | |
137 | list_add_rcu(&proto->node, &snap_list); | |
138 | } | |
139 | out: | |
140 | spin_unlock_bh(&snap_lock); | |
141 | ||
142 | synchronize_net(); | |
143 | return proto; | |
144 | } | |
145 | ||
146 | /* | |
147 | * Unregister SNAP clients. Protocols no longer want to play with us ... | |
148 | */ | |
149 | void unregister_snap_client(struct datalink_proto *proto) | |
150 | { | |
151 | spin_lock_bh(&snap_lock); | |
152 | list_del_rcu(&proto->node); | |
153 | spin_unlock_bh(&snap_lock); | |
154 | ||
155 | synchronize_net(); | |
156 | ||
157 | kfree(proto); | |
158 | } | |
159 | ||
160 | MODULE_LICENSE("GPL"); |