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 <linux/slab.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_reset_transport_header(skb);
  53                 bh_lock_sock(sk);
  54                 if (!sock_owned_by_user(sk)) {
  55                         queued = x25_process_rx_frame(sk, skb);
  56                 } else {
  57                         queued = !sk_add_backlog(sk, skb);
  58                 }
  59                 bh_unlock_sock(sk);
  60                 sock_put(sk);
  61                 return queued;
  62         }
  63
  64         /*
  65          *      Is is a Call Request ? if so process it.
  66          */
  67         if (frametype == X25_CALL_REQUEST)
  68                 return x25_rx_call_request(skb, nb, lci);
  69
  70         /*
  71          *      Its not a Call Request, nor is it a control frame.
  72          *      Can we forward it?
  73          */
  74
  75         if (x25_forward_data(lci, nb, skb)) {
  76                 if (frametype == X25_CLEAR_CONFIRMATION) {
  77                         x25_clear_forward_by_lci(lci);
  78                 }
  79                 kfree_skb(skb);
  80                 return 1;
  81         }
  82
  83 /*
  84         x25_transmit_clear_request(nb, lci, 0x0D);
  85 */
  86
  87         if (frametype != X25_CLEAR_CONFIRMATION)
  88                 printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype);
  89
  90         return 0;
  91 }
  92
  93 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
  94                            struct packet_type *ptype, struct net_device *orig_dev)
  95 {
  96         struct sk_buff *nskb;
  97         struct x25_neigh *nb;
  98
  99         if (!net_eq(dev_net(dev), &init_net))
 100                 goto drop;
 101
 102         nskb = skb_copy(skb, GFP_ATOMIC);
 103         if (!nskb)
 104                 goto drop;
 105         kfree_skb(skb);
 106         skb = nskb;
 107
 108         /*
 109          * Packet received from unrecognised device, throw it away.
 110          */
 111         nb = x25_get_neigh(dev);
 112         if (!nb) {
 113                 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name);
 114                 goto drop;
 115         }
 116
 117         switch (skb->data[0]) {
 118                 case 0x00:
 119                         skb_pull(skb, 1);
 120                         if (x25_receive_data(skb, nb)) {
 121                                 x25_neigh_put(nb);
 122                                 goto out;
 123                         }
 124                         break;
 125                 case 0x01:
 126                         x25_link_established(nb);
 127                         break;
 128                 case 0x02:
 129                         x25_link_terminated(nb);
 130                         break;
 131         }
 132         x25_neigh_put(nb);
 133 drop:
 134         kfree_skb(skb);
 135 out:
 136         return 0;
 137 }
 138
 139 void x25_establish_link(struct x25_neigh *nb)
 140 {
 141         struct sk_buff *skb;
 142         unsigned char *ptr;
 143
 144         switch (nb->dev->type) {
 145                 case ARPHRD_X25:
 146                         if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
 147                                 printk(KERN_ERR "x25_dev: out of memory\n");
 148                                 return;
 149                         }
 150                         ptr  = skb_put(skb, 1);
 151                         *ptr = 0x01;
 152                         break;
 153
 154 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 155                 case ARPHRD_ETHER:
 156                         return;
 157 #endif
 158                 default:
 159                         return;
 160         }
 161
 162         skb->protocol = htons(ETH_P_X25);
 163         skb->dev      = nb->dev;
 164
 165         dev_queue_xmit(skb);
 166 }
 167
 168 void x25_terminate_link(struct x25_neigh *nb)
 169 {
 170         struct sk_buff *skb;
 171         unsigned char *ptr;
 172
 173 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 174         if (nb->dev->type == ARPHRD_ETHER)
 175                 return;
 176 #endif
 177         if (nb->dev->type != ARPHRD_X25)
 178                 return;
 179
 180         skb = alloc_skb(1, GFP_ATOMIC);
 181         if (!skb) {
 182                 printk(KERN_ERR "x25_dev: out of memory\n");
 183                 return;
 184         }
 185
 186         ptr  = skb_put(skb, 1);
 187         *ptr = 0x02;
 188
 189         skb->protocol = htons(ETH_P_X25);
 190         skb->dev      = nb->dev;
 191         dev_queue_xmit(skb);
 192 }
 193
 194 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
 195 {
 196         unsigned char *dptr;
 197
 198         skb_reset_network_header(skb);
 199
 200         switch (nb->dev->type) {
 201                 case ARPHRD_X25:
 202                         dptr  = skb_push(skb, 1);
 203                         *dptr = 0x00;
 204                         break;
 205
 206 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 207                 case ARPHRD_ETHER:
 208                         kfree_skb(skb);
 209                         return;
 210 #endif
 211                 default:
 212                         kfree_skb(skb);
 213                         return;
 214         }
 215
 216         skb->protocol = htons(ETH_P_X25);
 217         skb->dev      = nb->dev;
 218
 219         dev_queue_xmit(skb);
 220 }