net/802/p8022.c

   1 /*
   2  *      NET3:   Support for 802.2 demultiplexing off Ethernet (Token ring
   3  *              is kept separate see p8022tr.c)
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  *              Demultiplex 802.2 encoded protocols. We match the entry by the
  10  *              SSAP/DSAP pair and then deliver to the registered datalink that
  11  *              matches. The control byte is ignored and handling of such items
  12  *              is up to the routine passed the frame.
  13  *
  14  *              Unlike the 802.3 datalink we have a list of 802.2 entries as there
  15  *              are multiple protocols to demux. The list is currently short (3 or
  16  *              4 entries at most). The current demux assumes this.
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/netdevice.h>
  21 #include <linux/skbuff.h>
  22 #include <net/datalink.h>
  23 #include <linux/mm.h>
  24 #include <linux/in.h>
  25 #include <linux/init.h>
  26 #include <net/p8022.h>
  27
  28 static struct datalink_proto *p8022_list = NULL;
  29
  30 /*
  31  *      We don't handle the loopback SAP stuff, the extended
  32  *      802.2 command set, multicast SAP identifiers and non UI
  33  *      frames. We have the absolute minimum needed for IPX,
  34  *      IP and Appletalk phase 2. See the llc_* routines for
  35  *      support libraries if your protocol needs these.
  36  */
  37
  38 static struct datalink_proto *find_8022_client(unsigned char type)
  39 {
  40         struct datalink_proto   *proto;
  41
  42         for (proto = p8022_list;
  43                 ((proto != NULL) && (*(proto->type) != type));
  44                 proto = proto->next)
  45                 ;
  46
  47         return proto;
  48 }
  49
  50 int p8022_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt)
  51 {
  52         struct datalink_proto   *proto;
  53
  54         proto = find_8022_client(*(skb->h.raw));
  55         if (proto != NULL)
  56         {
  57                 skb->h.raw += 3;
  58                 skb->nh.raw += 3;
  59                 skb_pull(skb,3);
  60                 return proto->rcvfunc(skb, dev, pt);
  61         }
  62
  63         skb->sk = NULL;
  64         kfree_skb(skb);
  65         return 0;
  66 }
  67
  68 static void p8022_datalink_header(struct datalink_proto *dl,
  69                 struct sk_buff *skb, unsigned char *dest_node)
  70 {
  71         struct net_device       *dev = skb->dev;
  72         unsigned char   *rawp;
  73
  74         rawp = skb_push(skb,3);
  75         *rawp++ = dl->type[0];
  76         *rawp++ = dl->type[0];
  77         *rawp = 0x03;   /* UI */
  78         dev->hard_header(skb, dev, ETH_P_802_3, dest_node, NULL, skb->len);
  79 }
  80
  81 static struct packet_type p8022_packet_type =
  82 {
  83         0,      /* MUTTER ntohs(ETH_P_8022),*/
  84         NULL,           /* All devices */
  85         p8022_rcv,
  86         NULL,
  87         NULL,
  88 };
  89
  90 EXPORT_SYMBOL(register_8022_client);
  91 EXPORT_SYMBOL(unregister_8022_client);
  92
  93 static int __init p8022_init(void)
  94 {
  95         p8022_packet_type.type=htons(ETH_P_802_2);
  96         dev_add_pack(&p8022_packet_type);
  97         return 0;
  98 }
  99
 100 module_init(p8022_init);
 101
 102 struct datalink_proto *register_8022_client(unsigned char type, int (*rcvfunc)(struct sk_buff *, struct net_device *, struct packet_type *))
 103 {
 104         struct datalink_proto   *proto;
 105
 106         if (find_8022_client(type) != NULL)
 107                 return NULL;
 108
 109         proto = (struct datalink_proto *) kmalloc(sizeof(*proto), GFP_ATOMIC);
 110         if (proto != NULL) {
 111                 proto->type[0] = type;
 112                 proto->type_len = 1;
 113                 proto->rcvfunc = rcvfunc;
 114                 proto->header_length = 3;
 115                 proto->datalink_header = p8022_datalink_header;
 116                 proto->string_name = "802.2";
 117                 proto->next = p8022_list;
 118                 p8022_list = proto;
 119         }
 120
 121         return proto;
 122 }
 123
 124 void unregister_8022_client(unsigned char type)
 125 {
 126         struct datalink_proto *tmp, **clients = &p8022_list;
 127         unsigned long flags;
 128
 129         save_flags(flags);
 130         cli();
 131
 132         while ((tmp = *clients) != NULL)
 133         {
 134                 if (tmp->type[0] == type) {
 135                         *clients = tmp->next;
 136                         kfree(tmp);
 137                         break;
 138                 } else {
 139                         clients = &tmp->next;
 140                 }
 141         }
 142
 143         restore_flags(flags);
 144 }