2 * SNAP data link layer. Derived from 802.2
4 * Alan Cox <Alan.Cox@linux.org>, from the 802.2 layer by Greg Page.
5 * Merged in additions from Greg Page's psnap.c.
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
13 #include <linux/module.h>
14 #include <linux/netdevice.h>
15 #include <linux/skbuff.h>
16 #include <net/datalink.h>
17 #include <net/p8022.h>
18 #include <net/psnap.h>
21 #include <linux/init.h>
23 static struct datalink_proto *snap_list = NULL;
24 static struct datalink_proto *snap_dl = NULL; /* 802.2 DL for SNAP */
27 * Find a snap client by matching the 5 bytes.
30 static struct datalink_proto *find_snap_client(unsigned char *desc)
32 struct datalink_proto *proto;
34 for (proto = snap_list; proto != NULL && memcmp(proto->type, desc, 5) ; proto = proto->next);
39 * A SNAP packet has arrived
42 int snap_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt)
44 static struct packet_type psnap_packet_type =
47 NULL, /* All Devices */
53 struct datalink_proto *proto;
55 proto = find_snap_client(skb->h.raw);
65 if (psnap_packet_type.type == 0)
66 psnap_packet_type.type=htons(ETH_P_SNAP);
68 return proto->rcvfunc(skb, dev, &psnap_packet_type);
76 * Put a SNAP header on a frame and pass to 802.2
79 static void snap_datalink_header(struct datalink_proto *dl, struct sk_buff *skb, unsigned char *dest_node)
81 memcpy(skb_push(skb,5),dl->type,5);
82 snap_dl->datalink_header(snap_dl, skb, dest_node);
86 * Set up the SNAP layer
89 EXPORT_SYMBOL(register_snap_client);
90 EXPORT_SYMBOL(unregister_snap_client);
92 static int __init snap_init(void)
94 snap_dl=register_8022_client(0xAA, snap_rcv);
96 printk("SNAP - unable to register with 802.2\n");
99 module_init(snap_init);
102 * Register SNAP clients. We don't yet use this for IP.
105 struct datalink_proto *register_snap_client(unsigned char *desc, int (*rcvfunc)(struct sk_buff *, struct net_device *, struct packet_type *))
107 struct datalink_proto *proto;
109 if (find_snap_client(desc) != NULL)
112 proto = (struct datalink_proto *) kmalloc(sizeof(*proto), GFP_ATOMIC);
115 memcpy(proto->type, desc,5);
117 proto->rcvfunc = rcvfunc;
118 proto->header_length = 5+snap_dl->header_length;
119 proto->datalink_header = snap_datalink_header;
120 proto->string_name = "SNAP";
121 proto->next = snap_list;
129 * Unregister SNAP clients. Protocols no longer want to play with us ...
132 void unregister_snap_client(unsigned char *desc)
134 struct datalink_proto **clients = &snap_list;
135 struct datalink_proto *tmp;
141 while ((tmp = *clients) != NULL)
143 if (memcmp(tmp->type,desc,5) == 0)
145 *clients = tmp->next;
150 clients = &tmp->next;
153 restore_flags(flags);