psnap.c
上传用户:jlfgdled
上传日期:2013-04-10
资源大小:33168k
文件大小:3k
- /*
- * 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 802.2n");
- 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);
- }