net/x25/x25_dev.c

   1 /*
   2  *      X.25 Packet Layer release 002
   3  *
   4  *      This is ALPHA test software. This code may break your machine, randomly fail to work with new
   5  *      releases, misbehave and/or generally screw up. It might even work.
   6  *
   7  *      This code REQUIRES 2.1.15 or higher
   8  *
   9  *      This module:
  10  *              This module is free software; you can redistribute it and/or
  11  *              modify it under the terms of the GNU General Public License
  12  *              as published by the Free Software Foundation; either version
  13  *              2 of the License, or (at your option) any later version.
  14  *
  15  *      History
  16  *      X.25 001        Jonathan Naylor Started coding.
  17  *      2000-09-04      Henner Eisen    Prevent freeing a dangling skb.
  18  */
  19
  20 #include <linux/kernel.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/skbuff.h>
  23 #include <net/sock.h>
  24 #include <linux/if_arp.h>
  25 #include <net/x25.h>
  26
  27 static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
  28 {
  29         struct sock *sk;
  30         unsigned short frametype;
  31         unsigned int lci;
  32
  33         frametype = skb->data[2];
  34         lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
  35
  36         /*
  37          *      LCI of zero is always for us, and its always a link control
  38          *      frame.
  39          */
  40         if (lci == 0) {
  41                 x25_link_control(skb, nb, frametype);
  42                 return 0;
  43         }
  44
  45         /*
  46          *      Find an existing socket.
  47          */
  48         if ((sk = x25_find_socket(lci, nb)) != NULL) {
  49                 int queued = 1;
  50
  51                 skb_reset_transport_header(skb);
  52                 bh_lock_sock(sk);
  53                 if (!sock_owned_by_user(sk)) {
  54                         queued = x25_process_rx_frame(sk, skb);
  55                 } else {
  56                         queued = !sk_add_backlog(sk, skb);
  57                 }
  58                 bh_unlock_sock(sk);
  59                 sock_put(sk);
  60                 return queued;
  61         }
  62
  63         /*
  64          *      Is is a Call Request ? if so process it.
  65          */
  66         if (frametype == X25_CALL_REQUEST)
  67                 return x25_rx_call_request(skb, nb, lci);
  68
  69         /*
  70          *      Its not a Call Request, nor is it a control frame.
  71          *      Can we forward it?
  72          */
  73
  74         if (x25_forward_data(lci, nb, skb)) {
  75                 if (frametype == X25_CLEAR_CONFIRMATION) {
  76                         x25_clear_forward_by_lci(lci);
  77                 }
  78                 kfree_skb(skb);
  79                 return 1;
  80         }
  81
  82 /*
  83         x25_transmit_clear_request(nb, lci, 0x0D);
  84 */
  85
  86         if (frametype != X25_CLEAR_CONFIRMATION)
  87                 printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype);
  88
  89         return 0;
  90 }
  91
  92 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
  93                            struct packet_type *ptype, struct net_device *orig_dev)
  94 {
  95         struct sk_buff *nskb;
  96         struct x25_neigh *nb;
  97
  98         if (!net_eq(dev_net(dev), &init_net))
  99                 goto drop;
 100
 101         nskb = skb_copy(skb, GFP_ATOMIC);
 102         if (!nskb)
 103                 goto drop;
 104         kfree_skb(skb);
 105         skb = nskb;
 106
 107         /*
 108          * Packet received from unrecognised device, throw it away.
 109          */
 110         nb = x25_get_neigh(dev);
 111         if (!nb) {
 112                 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name);
 113                 goto drop;
 114         }
 115
 116         switch (skb->data[0]) {
 117                 case 0x00:
 118                         skb_pull(skb, 1);
 119                         if (x25_receive_data(skb, nb)) {
 120                                 x25_neigh_put(nb);
 121                                 goto out;
 122                         }
 123                         break;
 124                 case 0x01:
 125                         x25_link_established(nb);
 126                         break;
 127                 case 0x02:
 128                         x25_link_terminated(nb);
 129                         break;
 130         }
 131         x25_neigh_put(nb);
 132 drop:
 133         kfree_skb(skb);
 134 out:
 135         return 0;
 136 }
 137
 138 void x25_establish_link(struct x25_neigh *nb)
 139 {
 140         struct sk_buff *skb;
 141         unsigned char *ptr;
 142
 143         switch (nb->dev->type) {
 144                 case ARPHRD_X25:
 145                         if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
 146                                 printk(KERN_ERR "x25_dev: out of memory\n");
 147                                 return;
 148                         }
 149                         ptr  = skb_put(skb, 1);
 150                         *ptr = 0x01;
 151                         break;
 152
 153 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 154                 case ARPHRD_ETHER:
 155                         return;
 156 #endif
 157                 default:
 158                         return;
 159         }
 160
 161         skb->protocol = htons(ETH_P_X25);
 162         skb->dev      = nb->dev;
 163
 164         dev_queue_xmit(skb);
 165 }
 166
 167 void x25_terminate_link(struct x25_neigh *nb)
 168 {
 169         struct sk_buff *skb;
 170         unsigned char *ptr;
 171
 172 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 173         if (nb->dev->type == ARPHRD_ETHER)
 174                 return;
 175 #endif
 176         if (nb->dev->type != ARPHRD_X25)
 177                 return;
 178
 179         skb = alloc_skb(1, GFP_ATOMIC);
 180         if (!skb) {
 181                 printk(KERN_ERR "x25_dev: out of memory\n");
 182                 return;
 183         }
 184
 185         ptr  = skb_put(skb, 1);
 186         *ptr = 0x02;
 187
 188         skb->protocol = htons(ETH_P_X25);
 189         skb->dev      = nb->dev;
 190         dev_queue_xmit(skb);
 191 }
 192
 193 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
 194 {
 195         unsigned char *dptr;
 196
 197         skb_reset_network_header(skb);
 198
 199         switch (nb->dev->type) {
 200                 case ARPHRD_X25:
 201                         dptr  = skb_push(skb, 1);
 202                         *dptr = 0x00;
 203                         break;
 204
 205 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 206                 case ARPHRD_ETHER:
 207                         kfree_skb(skb);
 208                         return;
 209 #endif
 210                 default:
 211                         kfree_skb(skb);
 212                         return;
 213         }
 214
 215         skb->protocol = htons(ETH_P_X25);
 216         skb->dev      = nb->dev;
 217
 218         dev_queue_xmit(skb);
 219 }