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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> | |
82524746 | 23 | #include <linux/rculist.h> |
1da177e4 LT |
24 | |
25 | static LIST_HEAD(snap_list); | |
26 | static DEFINE_SPINLOCK(snap_lock); | |
27 | static struct llc_sap *snap_sap; | |
28 | ||
29 | /* | |
30 | * Find a snap client by matching the 5 bytes. | |
31 | */ | |
32 | static struct datalink_proto *find_snap_client(unsigned char *desc) | |
33 | { | |
34 | struct list_head *entry; | |
35 | struct datalink_proto *proto = NULL, *p; | |
36 | ||
37 | list_for_each_rcu(entry, &snap_list) { | |
38 | p = list_entry(entry, struct datalink_proto, node); | |
39 | if (!memcmp(p->type, desc, 5)) { | |
40 | proto = p; | |
41 | break; | |
42 | } | |
43 | } | |
44 | return proto; | |
45 | } | |
46 | ||
47 | /* | |
48 | * A SNAP packet has arrived | |
49 | */ | |
50 | static int snap_rcv(struct sk_buff *skb, struct net_device *dev, | |
f2ccd8fa | 51 | struct packet_type *pt, struct net_device *orig_dev) |
1da177e4 LT |
52 | { |
53 | int rc = 1; | |
54 | struct datalink_proto *proto; | |
55 | static struct packet_type snap_packet_type = { | |
56 | .type = __constant_htons(ETH_P_SNAP), | |
57 | }; | |
58 | ||
d92a7db7 HX |
59 | if (unlikely(!pskb_may_pull(skb, 5))) |
60 | goto drop; | |
61 | ||
1da177e4 | 62 | rcu_read_lock(); |
9c70220b | 63 | proto = find_snap_client(skb_transport_header(skb)); |
1da177e4 LT |
64 | if (proto) { |
65 | /* Pass the frame on. */ | |
b0e380b1 | 66 | skb->transport_header += 5; |
cbb042f9 | 67 | skb_pull_rcsum(skb, 5); |
f2ccd8fa | 68 | rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev); |
1da177e4 | 69 | } |
1da177e4 | 70 | rcu_read_unlock(); |
d92a7db7 HX |
71 | |
72 | if (unlikely(!proto)) | |
73 | goto drop; | |
74 | ||
75 | out: | |
1da177e4 | 76 | return rc; |
d92a7db7 HX |
77 | |
78 | drop: | |
79 | kfree_skb(skb); | |
80 | goto out; | |
1da177e4 LT |
81 | } |
82 | ||
83 | /* | |
84 | * Put a SNAP header on a frame and pass to 802.2 | |
85 | */ | |
86 | static int snap_request(struct datalink_proto *dl, | |
87 | struct sk_buff *skb, u8 *dest) | |
88 | { | |
89 | memcpy(skb_push(skb, 5), dl->type, 5); | |
90 | llc_build_and_send_ui_pkt(snap_sap, skb, dest, snap_sap->laddr.lsap); | |
91 | return 0; | |
92 | } | |
93 | ||
94 | /* | |
95 | * Set up the SNAP layer | |
96 | */ | |
97 | EXPORT_SYMBOL(register_snap_client); | |
98 | EXPORT_SYMBOL(unregister_snap_client); | |
99 | ||
100 | static char snap_err_msg[] __initdata = | |
101 | KERN_CRIT "SNAP - unable to register with 802.2\n"; | |
102 | ||
103 | static int __init snap_init(void) | |
104 | { | |
105 | snap_sap = llc_sap_open(0xAA, snap_rcv); | |
106 | ||
107 | if (!snap_sap) | |
108 | printk(snap_err_msg); | |
109 | ||
110 | return 0; | |
111 | } | |
112 | ||
113 | module_init(snap_init); | |
114 | ||
115 | static void __exit snap_exit(void) | |
116 | { | |
6e2144b7 | 117 | llc_sap_put(snap_sap); |
1da177e4 LT |
118 | } |
119 | ||
120 | module_exit(snap_exit); | |
121 | ||
122 | ||
123 | /* | |
124 | * Register SNAP clients. We don't yet use this for IP. | |
125 | */ | |
126 | struct datalink_proto *register_snap_client(unsigned char *desc, | |
127 | int (*rcvfunc)(struct sk_buff *, | |
9afa0949 | 128 | struct net_device *, |
f2ccd8fa DM |
129 | struct packet_type *, |
130 | struct net_device *)) | |
1da177e4 LT |
131 | { |
132 | struct datalink_proto *proto = NULL; | |
133 | ||
134 | spin_lock_bh(&snap_lock); | |
135 | ||
136 | if (find_snap_client(desc)) | |
137 | goto out; | |
138 | ||
139 | proto = kmalloc(sizeof(*proto), GFP_ATOMIC); | |
140 | if (proto) { | |
141 | memcpy(proto->type, desc,5); | |
142 | proto->rcvfunc = rcvfunc; | |
143 | proto->header_length = 5 + 3; /* snap + 802.2 */ | |
144 | proto->request = snap_request; | |
145 | list_add_rcu(&proto->node, &snap_list); | |
146 | } | |
147 | out: | |
148 | spin_unlock_bh(&snap_lock); | |
149 | ||
150 | synchronize_net(); | |
151 | return proto; | |
152 | } | |
153 | ||
154 | /* | |
155 | * Unregister SNAP clients. Protocols no longer want to play with us ... | |
156 | */ | |
157 | void unregister_snap_client(struct datalink_proto *proto) | |
158 | { | |
159 | spin_lock_bh(&snap_lock); | |
160 | list_del_rcu(&proto->node); | |
161 | spin_unlock_bh(&snap_lock); | |
162 | ||
163 | synchronize_net(); | |
164 | ||
165 | kfree(proto); | |
166 | } | |
167 | ||
168 | MODULE_LICENSE("GPL"); |