Home Home > GIT Browse
summaryrefslogtreecommitdiff
blob: 6e7c2120b83ff6a678ca0e3e33f377b713a711cf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
/*
 *	SNAP data link layer. Derived from 802.2
 *
 *		Alan Cox <Alan.Cox@linux.org>,
 *		from the 802.2 layer by Greg Page.
 *		Merged in additions from Greg Page's psnap.c.
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/datalink.h>
#include <net/llc.h>
#include <net/psnap.h>
#include <linux/mm.h>
#include <linux/in.h>
#include <linux/init.h>

static LIST_HEAD(snap_list);
static DEFINE_SPINLOCK(snap_lock);
static struct llc_sap *snap_sap;

/*
 *	Find a snap client by matching the 5 bytes.
 */
static struct datalink_proto *find_snap_client(unsigned char *desc)
{
	struct list_head *entry;
	struct datalink_proto *proto = NULL, *p;

	list_for_each_rcu(entry, &snap_list) {
		p = list_entry(entry, struct datalink_proto, node);
		if (!memcmp(p->type, desc, 5)) {
			proto = p;
			break;
		}
	}
	return proto;
}

/*
 *	A SNAP packet has arrived
 */
static int snap_rcv(struct sk_buff *skb, struct net_device *dev,
		    struct packet_type *pt, struct net_device *orig_dev)
{
	int rc = 1;
	struct datalink_proto *proto;
	static struct packet_type snap_packet_type = {
		.type = __constant_htons(ETH_P_SNAP),
	};

	rcu_read_lock();
	proto = find_snap_client(skb->h.raw);
	if (proto) {
		/* Pass the frame on. */
		skb->h.raw  += 5;
		skb_pull_rcsum(skb, 5);
		rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev);
	} else {
		skb->sk = NULL;
		kfree_skb(skb);
		rc = 1;
	}

	rcu_read_unlock();
	return rc;
}

/*
 *	Put a SNAP header on a frame and pass to 802.2
 */
static int snap_request(struct datalink_proto *dl,
			struct sk_buff *skb, u8 *dest)
{
	memcpy(skb_push(skb, 5), dl->type, 5);
	llc_build_and_send_ui_pkt(snap_sap, skb, dest, snap_sap->laddr.lsap);
	return 0;
}

/*
 *	Set up the SNAP layer
 */
EXPORT_SYMBOL(register_snap_client);
EXPORT_SYMBOL(unregister_snap_client);

static char snap_err_msg[] __initdata =
	KERN_CRIT "SNAP - unable to register with 802.2\n";

static int __init snap_init(void)
{
	snap_sap = llc_sap_open(0xAA, snap_rcv);

	if (!snap_sap)
		printk(snap_err_msg);

	return 0;
}

module_init(snap_init);

static void __exit snap_exit(void)
{
	llc_sap_put(snap_sap);
}

module_exit(snap_exit);


/*
 *	Register SNAP clients. We don't yet use this for IP.
 */
struct datalink_proto *register_snap_client(unsigned char *desc,
					    int (*rcvfunc)(struct sk_buff *,
							   struct net_device *,
							   struct packet_type *,
							   struct net_device *))
{
	struct datalink_proto *proto = NULL;

	spin_lock_bh(&snap_lock);

	if (find_snap_client(desc))
		goto out;

	proto = kmalloc(sizeof(*proto), GFP_ATOMIC);
	if (proto) {
		memcpy(proto->type, desc,5);
		proto->rcvfunc		= rcvfunc;
		proto->header_length	= 5 + 3; /* snap + 802.2 */
		proto->request		= snap_request;
		list_add_rcu(&proto->node, &snap_list);
	}
out:
	spin_unlock_bh(&snap_lock);

	synchronize_net();
	return proto;
}

/*
 *	Unregister SNAP clients. Protocols no longer want to play with us ...
 */
void unregister_snap_client(struct datalink_proto *proto)
{
	spin_lock_bh(&snap_lock);
	list_del_rcu(&proto->node);
	spin_unlock_bh(&snap_lock);

	synchronize_net();

	kfree(proto);
}

MODULE_LICENSE("GPL");