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->h.raw = skb->data;
  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                 return queued;
  60         }
  61
  62         /*
  63          *      Is is a Call Request ? if so process it.
  64          */
  65         if (frametype == X25_CALL_REQUEST)
  66                 return x25_rx_call_request(skb, nb, lci);
  67
  68         /*
  69          *      Its not a Call Request, nor is it a control frame.
  70          *      Let caller throw it away.
  71          */
  72 /*
  73         x25_transmit_clear_request(nb, lci, 0x0D);
  74 */
  75
  76         if (frametype != X25_CLEAR_CONFIRMATION)
  77                 printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype);
  78
  79         return 0;
  80 }
  81
  82 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
  83                            struct packet_type *ptype, struct net_device *orig_dev)
  84 {
  85         struct sk_buff *nskb;
  86         struct x25_neigh *nb;
  87
  88         nskb = skb_copy(skb, GFP_ATOMIC);
  89         if (!nskb)
  90                 goto drop;
  91         kfree_skb(skb);
  92         skb = nskb;
  93
  94         /*
  95          * Packet received from unrecognised device, throw it away.
  96          */
  97         nb = x25_get_neigh(dev);
  98         if (!nb) {
  99                 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name);
 100                 goto drop;
 101         }
 102
 103         switch (skb->data[0]) {
 104                 case 0x00:
 105                         skb_pull(skb, 1);
 106                         if (x25_receive_data(skb, nb)) {
 107                                 x25_neigh_put(nb);
 108                                 goto out;
 109                         }
 110                         break;
 111                 case 0x01:
 112                         x25_link_established(nb);
 113                         break;
 114                 case 0x02:
 115                         x25_link_terminated(nb);
 116                         break;
 117         }
 118         x25_neigh_put(nb);
 119 drop:
 120         kfree_skb(skb);
 121 out:
 122         return 0;
 123 }
 124
 125 void x25_establish_link(struct x25_neigh *nb)
 126 {
 127         struct sk_buff *skb;
 128         unsigned char *ptr;
 129
 130         switch (nb->dev->type) {
 131                 case ARPHRD_X25:
 132                         if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
 133                                 printk(KERN_ERR "x25_dev: out of memory\n");
 134                                 return;
 135                         }
 136                         ptr  = skb_put(skb, 1);
 137                         *ptr = 0x01;
 138                         break;
 139
 140 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 141                 case ARPHRD_ETHER:
 142                         return;
 143 #endif
 144                 default:
 145                         return;
 146         }
 147
 148         skb->protocol = htons(ETH_P_X25);
 149         skb->dev      = nb->dev;
 150
 151         dev_queue_xmit(skb);
 152 }
 153
 154 void x25_terminate_link(struct x25_neigh *nb)
 155 {
 156         struct sk_buff *skb;
 157         unsigned char *ptr;
 158
 159 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 160         if (nb->dev->type == ARPHRD_ETHER)
 161                 return;
 162 #endif
 163         if (nb->dev->type != ARPHRD_X25)
 164                 return;
 165
 166         skb = alloc_skb(1, GFP_ATOMIC);
 167         if (!skb) {
 168                 printk(KERN_ERR "x25_dev: out of memory\n");
 169                 return;
 170         }
 171
 172         ptr  = skb_put(skb, 1);
 173         *ptr = 0x02;
 174
 175         skb->protocol = htons(ETH_P_X25);
 176         skb->dev      = nb->dev;
 177         dev_queue_xmit(skb);
 178 }
 179
 180 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
 181 {
 182         unsigned char *dptr;
 183
 184         skb->nh.raw = skb->data;
 185
 186         switch (nb->dev->type) {
 187                 case ARPHRD_X25:
 188                         dptr  = skb_push(skb, 1);
 189                         *dptr = 0x00;
 190                         break;
 191
 192 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 193                 case ARPHRD_ETHER:
 194                         kfree_skb(skb);
 195                         return;
 196 #endif
 197                 default:
 198                         kfree_skb(skb);
 199                         return;
 200         }
 201
 202         skb->protocol = htons(ETH_P_X25);
 203         skb->dev      = nb->dev;
 204
 205         dev_queue_xmit(skb);
 206 }