Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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> |
| 23 | |
| 24 | static LIST_HEAD(snap_list); |
| 25 | static DEFINE_SPINLOCK(snap_lock); |
| 26 | static struct llc_sap *snap_sap; |
| 27 | |
| 28 | /* |
| 29 | * Find a snap client by matching the 5 bytes. |
| 30 | */ |
| 31 | static struct datalink_proto *find_snap_client(unsigned char *desc) |
| 32 | { |
| 33 | struct list_head *entry; |
| 34 | struct datalink_proto *proto = NULL, *p; |
| 35 | |
| 36 | list_for_each_rcu(entry, &snap_list) { |
| 37 | p = list_entry(entry, struct datalink_proto, node); |
| 38 | if (!memcmp(p->type, desc, 5)) { |
| 39 | proto = p; |
| 40 | break; |
| 41 | } |
| 42 | } |
| 43 | return proto; |
| 44 | } |
| 45 | |
| 46 | /* |
| 47 | * A SNAP packet has arrived |
| 48 | */ |
| 49 | static int snap_rcv(struct sk_buff *skb, struct net_device *dev, |
David S. Miller | f2ccd8f | 2005-08-09 19:34:12 -0700 | [diff] [blame] | 50 | struct packet_type *pt, struct net_device *orig_dev) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 51 | { |
| 52 | int rc = 1; |
| 53 | struct datalink_proto *proto; |
| 54 | static struct packet_type snap_packet_type = { |
| 55 | .type = __constant_htons(ETH_P_SNAP), |
| 56 | }; |
| 57 | |
| 58 | rcu_read_lock(); |
| 59 | proto = find_snap_client(skb->h.raw); |
| 60 | if (proto) { |
| 61 | /* Pass the frame on. */ |
Stephen Hemminger | 42c5e15 | 2006-02-02 16:53:26 -0800 | [diff] [blame] | 62 | u8 *hdr = skb->data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 63 | skb->h.raw += 5; |
| 64 | skb_pull(skb, 5); |
Stephen Hemminger | 42c5e15 | 2006-02-02 16:53:26 -0800 | [diff] [blame] | 65 | skb_postpull_rcsum(skb, hdr, 5); |
David S. Miller | f2ccd8f | 2005-08-09 19:34:12 -0700 | [diff] [blame] | 66 | rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 67 | } else { |
| 68 | skb->sk = NULL; |
| 69 | kfree_skb(skb); |
| 70 | rc = 1; |
| 71 | } |
| 72 | |
| 73 | rcu_read_unlock(); |
| 74 | return rc; |
| 75 | } |
| 76 | |
| 77 | /* |
| 78 | * Put a SNAP header on a frame and pass to 802.2 |
| 79 | */ |
| 80 | static int snap_request(struct datalink_proto *dl, |
| 81 | struct sk_buff *skb, u8 *dest) |
| 82 | { |
| 83 | memcpy(skb_push(skb, 5), dl->type, 5); |
| 84 | llc_build_and_send_ui_pkt(snap_sap, skb, dest, snap_sap->laddr.lsap); |
| 85 | return 0; |
| 86 | } |
| 87 | |
| 88 | /* |
| 89 | * Set up the SNAP layer |
| 90 | */ |
| 91 | EXPORT_SYMBOL(register_snap_client); |
| 92 | EXPORT_SYMBOL(unregister_snap_client); |
| 93 | |
| 94 | static char snap_err_msg[] __initdata = |
| 95 | KERN_CRIT "SNAP - unable to register with 802.2\n"; |
| 96 | |
| 97 | static int __init snap_init(void) |
| 98 | { |
| 99 | snap_sap = llc_sap_open(0xAA, snap_rcv); |
| 100 | |
| 101 | if (!snap_sap) |
| 102 | printk(snap_err_msg); |
| 103 | |
| 104 | return 0; |
| 105 | } |
| 106 | |
| 107 | module_init(snap_init); |
| 108 | |
| 109 | static void __exit snap_exit(void) |
| 110 | { |
Arnaldo Carvalho de Melo | 6e2144b | 2005-09-22 04:43:05 -0300 | [diff] [blame] | 111 | llc_sap_put(snap_sap); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 112 | } |
| 113 | |
| 114 | module_exit(snap_exit); |
| 115 | |
| 116 | |
| 117 | /* |
| 118 | * Register SNAP clients. We don't yet use this for IP. |
| 119 | */ |
| 120 | struct datalink_proto *register_snap_client(unsigned char *desc, |
| 121 | int (*rcvfunc)(struct sk_buff *, |
| 122 | struct net_device *, |
David S. Miller | f2ccd8f | 2005-08-09 19:34:12 -0700 | [diff] [blame] | 123 | struct packet_type *, |
| 124 | struct net_device *)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 125 | { |
| 126 | struct datalink_proto *proto = NULL; |
| 127 | |
| 128 | spin_lock_bh(&snap_lock); |
| 129 | |
| 130 | if (find_snap_client(desc)) |
| 131 | goto out; |
| 132 | |
| 133 | proto = kmalloc(sizeof(*proto), GFP_ATOMIC); |
| 134 | if (proto) { |
| 135 | memcpy(proto->type, desc,5); |
| 136 | proto->rcvfunc = rcvfunc; |
| 137 | proto->header_length = 5 + 3; /* snap + 802.2 */ |
| 138 | proto->request = snap_request; |
| 139 | list_add_rcu(&proto->node, &snap_list); |
| 140 | } |
| 141 | out: |
| 142 | spin_unlock_bh(&snap_lock); |
| 143 | |
| 144 | synchronize_net(); |
| 145 | return proto; |
| 146 | } |
| 147 | |
| 148 | /* |
| 149 | * Unregister SNAP clients. Protocols no longer want to play with us ... |
| 150 | */ |
| 151 | void unregister_snap_client(struct datalink_proto *proto) |
| 152 | { |
| 153 | spin_lock_bh(&snap_lock); |
| 154 | list_del_rcu(&proto->node); |
| 155 | spin_unlock_bh(&snap_lock); |
| 156 | |
| 157 | synchronize_net(); |
| 158 | |
| 159 | kfree(proto); |
| 160 | } |
| 161 | |
| 162 | MODULE_LICENSE("GPL"); |