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/*
* 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/p8022.h>
#include <net/psnap.h>
#include <linux/mm.h>
#include <linux/in.h>
#include <linux/init.h>
static struct datalink_proto *snap_list = NULL;
static struct datalink_proto *snap_dl = NULL; /* 802.2 DL for SNAP */
/*
* Find a snap client by matching the 5 bytes.
*/
static struct datalink_proto *find_snap_client(unsigned char *desc)
{
struct datalink_proto *proto;
for (proto = snap_list; proto != NULL && memcmp(proto->type, desc, 5) ; proto = proto->next);
return proto;
}
/*
* A SNAP packet has arrived
*/
int snap_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt)
{
static struct packet_type psnap_packet_type =
{
0,
NULL, /* All Devices */
snap_rcv,
NULL,
NULL,
};
struct datalink_proto *proto;
proto = find_snap_client(skb->h.raw);
if (proto != NULL)
{
/*
* Pass the frame on.
*/
skb->h.raw += 5;
skb->nh.raw += 5;
skb_pull(skb,5);
if (psnap_packet_type.type == 0)
psnap_packet_type.type=htons(ETH_P_SNAP);
return proto->rcvfunc(skb, dev, &psnap_packet_type);
}
skb->sk = NULL;
kfree_skb(skb);
return 0;
}
/*
* Put a SNAP header on a frame and pass to 802.2
*/
static void snap_datalink_header(struct datalink_proto *dl, struct sk_buff *skb, unsigned char *dest_node)
{
memcpy(skb_push(skb,5),dl->type,5);
snap_dl->datalink_header(snap_dl, skb, dest_node);
}
/*
* Set up the SNAP layer
*/
EXPORT_SYMBOL(register_snap_client);
EXPORT_SYMBOL(unregister_snap_client);
static int __init snap_init(void)
{
snap_dl=register_8022_client(0xAA, snap_rcv);
if(snap_dl==NULL)
printk("SNAP - unable to register with 802.2\n");
return 0;
}
module_init(snap_init);
/*
* 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 datalink_proto *proto;
if (find_snap_client(desc) != NULL)
return NULL;
proto = (struct datalink_proto *) kmalloc(sizeof(*proto), GFP_ATOMIC);
if (proto != NULL)
{
memcpy(proto->type, desc,5);
proto->type_len = 5;
proto->rcvfunc = rcvfunc;
proto->header_length = 5+snap_dl->header_length;
proto->datalink_header = snap_datalink_header;
proto->string_name = "SNAP";
proto->next = snap_list;
snap_list = proto;
}
return proto;
}
/*
* Unregister SNAP clients. Protocols no longer want to play with us ...
*/
void unregister_snap_client(unsigned char *desc)
{
struct datalink_proto **clients = &snap_list;
struct datalink_proto *tmp;
unsigned long flags;
save_flags(flags);
cli();
while ((tmp = *clients) != NULL)
{
if (memcmp(tmp->type,desc,5) == 0)
{
*clients = tmp->next;
kfree(tmp);
break;
}
else
clients = &tmp->next;
}
restore_flags(flags);
}
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