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/config.h>
  21 #include <linux/kernel.h>
  22 #include <linux/netdevice.h>
  23 #include <linux/skbuff.h>
  24 #include <net/sock.h>
  25 #include <linux/if_arp.h>
  26 #include <net/x25.h>
  27
  28 static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
  29 {
  30         struct sock *sk;
  31         unsigned short frametype;
  32         unsigned int lci;
  33
  34         frametype = skb->data[2];
  35         lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
  36
  37         /*
  38          *      LCI of zero is always for us, and its always a link control
  39          *      frame.
  40          */
  41         if (lci == 0) {
  42                 x25_link_control(skb, nb, frametype);
  43                 return 0;
  44         }
  45
  46         /*
  47          *      Find an existing socket.
  48          */
  49         if ((sk = x25_find_socket(lci, nb)) != NULL) {
  50                 int queued = 1;
  51
  52                 skb->h.raw = skb->data;
  53                 bh_lock_sock(sk);
  54                 if (!sock_owned_by_user(sk)) {
  55                         queued = x25_process_rx_frame(sk, skb);
  56                 } else {
  57                         sk_add_backlog(sk, skb);
  58                 }
  59                 bh_unlock_sock(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          *      Let caller throw it away.
  72          */
  73 /*
  74         x25_transmit_clear_request(nb, lci, 0x0D);
  75 */
  76
  77         if (frametype != X25_CLEAR_CONFIRMATION)
  78                 printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype);
  79
  80         return 0;
  81 }
  82
  83 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
  84                            struct packet_type *ptype, struct net_device *orig_dev)
  85 {
  86         struct sk_buff *nskb;
  87         struct x25_neigh *nb;
  88
  89         nskb = skb_copy(skb, GFP_ATOMIC);
  90         if (!nskb)
  91                 goto drop;
  92         kfree_skb(skb);
  93         skb = nskb;
  94
  95         /*
  96          * Packet received from unrecognised device, throw it away.
  97          */
  98         nb = x25_get_neigh(dev);
  99         if (!nb) {
 100                 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name);
 101                 goto drop;
 102         }
 103
 104         switch (skb->data[0]) {
 105                 case 0x00:
 106                         skb_pull(skb, 1);
 107                         if (x25_receive_data(skb, nb)) {
 108                                 x25_neigh_put(nb);
 109                                 goto out;
 110                         }
 111                         break;
 112                 case 0x01:
 113                         x25_link_established(nb);
 114                         break;
 115                 case 0x02:
 116                         x25_link_terminated(nb);
 117                         break;
 118         }
 119         x25_neigh_put(nb);
 120 drop:
 121         kfree_skb(skb);
 122 out:
 123         return 0;
 124 }
 125
 126 void x25_establish_link(struct x25_neigh *nb)
 127 {
 128         struct sk_buff *skb;
 129         unsigned char *ptr;
 130
 131         switch (nb->dev->type) {
 132                 case ARPHRD_X25:
 133                         if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
 134                                 printk(KERN_ERR "x25_dev: out of memory\n");
 135                                 return;
 136                         }
 137                         ptr  = skb_put(skb, 1);
 138                         *ptr = 0x01;
 139                         break;
 140
 141 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 142                 case ARPHRD_ETHER:
 143                         return;
 144 #endif
 145                 default:
 146                         return;
 147         }
 148
 149         skb->protocol = htons(ETH_P_X25);
 150         skb->dev      = nb->dev;
 151
 152         dev_queue_xmit(skb);
 153 }
 154
 155 void x25_terminate_link(struct x25_neigh *nb)
 156 {
 157         struct sk_buff *skb;
 158         unsigned char *ptr;
 159
 160 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 161         if (nb->dev->type == ARPHRD_ETHER)
 162                 return;
 163 #endif
 164         if (nb->dev->type != ARPHRD_X25)
 165                 return;
 166
 167         skb = alloc_skb(1, GFP_ATOMIC);
 168         if (!skb) {
 169                 printk(KERN_ERR "x25_dev: out of memory\n");
 170                 return;
 171         }
 172
 173         ptr  = skb_put(skb, 1);
 174         *ptr = 0x02;
 175
 176         skb->protocol = htons(ETH_P_X25);
 177         skb->dev      = nb->dev;
 178         dev_queue_xmit(skb);
 179 }
 180
 181 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
 182 {
 183         unsigned char *dptr;
 184
 185         skb->nh.raw = skb->data;
 186
 187         switch (nb->dev->type) {
 188                 case ARPHRD_X25:
 189                         dptr  = skb_push(skb, 1);
 190                         *dptr = 0x00;
 191                         break;
 192
 193 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 194                 case ARPHRD_ETHER:
 195                         kfree_skb(skb);
 196                         return;
 197 #endif
 198                 default:
 199                         kfree_skb(skb);
 200                         return;
 201         }
 202
 203         skb->protocol = htons(ETH_P_X25);
 204         skb->dev      = nb->dev;
 205
 206         dev_queue_xmit(skb);
 207 }