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                         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         nskb = skb_copy(skb, GFP_ATOMIC);
  99         if (!nskb)
 100                 goto drop;
 101         kfree_skb(skb);
 102         skb = nskb;
 103
 104         /*
 105          * Packet received from unrecognised device, throw it away.
 106          */
 107         nb = x25_get_neigh(dev);
 108         if (!nb) {
 109                 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name);
 110                 goto drop;
 111         }
 112
 113         switch (skb->data[0]) {
 114                 case 0x00:
 115                         skb_pull(skb, 1);
 116                         if (x25_receive_data(skb, nb)) {
 117                                 x25_neigh_put(nb);
 118                                 goto out;
 119                         }
 120                         break;
 121                 case 0x01:
 122                         x25_link_established(nb);
 123                         break;
 124                 case 0x02:
 125                         x25_link_terminated(nb);
 126                         break;
 127         }
 128         x25_neigh_put(nb);
 129 drop:
 130         kfree_skb(skb);
 131 out:
 132         return 0;
 133 }
 134
 135 void x25_establish_link(struct x25_neigh *nb)
 136 {
 137         struct sk_buff *skb;
 138         unsigned char *ptr;
 139
 140         switch (nb->dev->type) {
 141                 case ARPHRD_X25:
 142                         if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
 143                                 printk(KERN_ERR "x25_dev: out of memory\n");
 144                                 return;
 145                         }
 146                         ptr  = skb_put(skb, 1);
 147                         *ptr = 0x01;
 148                         break;
 149
 150 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 151                 case ARPHRD_ETHER:
 152                         return;
 153 #endif
 154                 default:
 155                         return;
 156         }
 157
 158         skb->protocol = htons(ETH_P_X25);
 159         skb->dev      = nb->dev;
 160
 161         dev_queue_xmit(skb);
 162 }
 163
 164 void x25_terminate_link(struct x25_neigh *nb)
 165 {
 166         struct sk_buff *skb;
 167         unsigned char *ptr;
 168
 169 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 170         if (nb->dev->type == ARPHRD_ETHER)
 171                 return;
 172 #endif
 173         if (nb->dev->type != ARPHRD_X25)
 174                 return;
 175
 176         skb = alloc_skb(1, GFP_ATOMIC);
 177         if (!skb) {
 178                 printk(KERN_ERR "x25_dev: out of memory\n");
 179                 return;
 180         }
 181
 182         ptr  = skb_put(skb, 1);
 183         *ptr = 0x02;
 184
 185         skb->protocol = htons(ETH_P_X25);
 186         skb->dev      = nb->dev;
 187         dev_queue_xmit(skb);
 188 }
 189
 190 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
 191 {
 192         unsigned char *dptr;
 193
 194         skb_reset_network_header(skb);
 195
 196         switch (nb->dev->type) {
 197                 case ARPHRD_X25:
 198                         dptr  = skb_push(skb, 1);
 199                         *dptr = 0x00;
 200                         break;
 201
 202 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 203                 case ARPHRD_ETHER:
 204                         kfree_skb(skb);
 205                         return;
 206 #endif
 207                 default:
 208                         kfree_skb(skb);
 209                         return;
 210         }
 211
 212         skb->protocol = htons(ETH_P_X25);
 213         skb->dev      = nb->dev;
 214
 215         dev_queue_xmit(skb);
 216 }