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 #include <net/x25device.h>
  28
  29 static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
  30 {
  31         struct sock *sk;
  32         unsigned short frametype;
  33         unsigned int lci;
  34
  35         frametype = skb->data[2];
  36         lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
  37
  38         /*
  39          *      LCI of zero is always for us, and its always a link control
  40          *      frame.
  41          */
  42         if (lci == 0) {
  43                 x25_link_control(skb, nb, frametype);
  44                 return 0;
  45         }
  46
  47         /*
  48          *      Find an existing socket.
  49          */
  50         if ((sk = x25_find_socket(lci, nb)) != NULL) {
  51                 int queued = 1;
  52
  53                 skb_reset_transport_header(skb);
  54                 bh_lock_sock(sk);
  55                 if (!sock_owned_by_user(sk)) {
  56                         queued = x25_process_rx_frame(sk, skb);
  57                 } else {
  58                         queued = !sk_add_backlog(sk, skb);
  59                 }
  60                 bh_unlock_sock(sk);
  61                 sock_put(sk);
  62                 return queued;
  63         }
  64
  65         /*
  66          *      Is is a Call Request ? if so process it.
  67          */
  68         if (frametype == X25_CALL_REQUEST)
  69                 return x25_rx_call_request(skb, nb, lci);
  70
  71         /*
  72          *      Its not a Call Request, nor is it a control frame.
  73          *      Can we forward it?
  74          */
  75
  76         if (x25_forward_data(lci, nb, skb)) {
  77                 if (frametype == X25_CLEAR_CONFIRMATION) {
  78                         x25_clear_forward_by_lci(lci);
  79                 }
  80                 kfree_skb(skb);
  81                 return 1;
  82         }
  83
  84 /*
  85         x25_transmit_clear_request(nb, lci, 0x0D);
  86 */
  87
  88         if (frametype != X25_CLEAR_CONFIRMATION)
  89                 printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype);
  90
  91         return 0;
  92 }
  93
  94 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
  95                            struct packet_type *ptype, struct net_device *orig_dev)
  96 {
  97         struct sk_buff *nskb;
  98         struct x25_neigh *nb;
  99
 100         if (!net_eq(dev_net(dev), &init_net))
 101                 goto drop;
 102
 103         nskb = skb_copy(skb, GFP_ATOMIC);
 104         if (!nskb)
 105                 goto drop;
 106         kfree_skb(skb);
 107         skb = nskb;
 108
 109         /*
 110          * Packet received from unrecognised device, throw it away.
 111          */
 112         nb = x25_get_neigh(dev);
 113         if (!nb) {
 114                 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name);
 115                 goto drop;
 116         }
 117
 118         switch (skb->data[0]) {
 119
 120         case X25_IFACE_DATA:
 121                 skb_pull(skb, 1);
 122                 if (x25_receive_data(skb, nb)) {
 123                         x25_neigh_put(nb);
 124                         goto out;
 125                 }
 126                 break;
 127
 128         case X25_IFACE_CONNECT:
 129                 x25_link_established(nb);
 130                 break;
 131
 132         case X25_IFACE_DISCONNECT:
 133                 x25_link_terminated(nb);
 134                 break;
 135         }
 136         x25_neigh_put(nb);
 137 drop:
 138         kfree_skb(skb);
 139 out:
 140         return 0;
 141 }
 142
 143 void x25_establish_link(struct x25_neigh *nb)
 144 {
 145         struct sk_buff *skb;
 146         unsigned char *ptr;
 147
 148         switch (nb->dev->type) {
 149         case ARPHRD_X25:
 150                 if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
 151                         printk(KERN_ERR "x25_dev: out of memory\n");
 152                         return;
 153                 }
 154                 ptr  = skb_put(skb, 1);
 155                 *ptr = X25_IFACE_CONNECT;
 156                 break;
 157
 158 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 159         case ARPHRD_ETHER:
 160                 return;
 161 #endif
 162         default:
 163                 return;
 164         }
 165
 166         skb->protocol = htons(ETH_P_X25);
 167         skb->dev      = nb->dev;
 168
 169         dev_queue_xmit(skb);
 170 }
 171
 172 void x25_terminate_link(struct x25_neigh *nb)
 173 {
 174         struct sk_buff *skb;
 175         unsigned char *ptr;
 176
 177 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 178         if (nb->dev->type == ARPHRD_ETHER)
 179                 return;
 180 #endif
 181         if (nb->dev->type != ARPHRD_X25)
 182                 return;
 183
 184         skb = alloc_skb(1, GFP_ATOMIC);
 185         if (!skb) {
 186                 printk(KERN_ERR "x25_dev: out of memory\n");
 187                 return;
 188         }
 189
 190         ptr  = skb_put(skb, 1);
 191         *ptr = X25_IFACE_DISCONNECT;
 192
 193         skb->protocol = htons(ETH_P_X25);
 194         skb->dev      = nb->dev;
 195         dev_queue_xmit(skb);
 196 }
 197
 198 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
 199 {
 200         unsigned char *dptr;
 201
 202         skb_reset_network_header(skb);
 203
 204         switch (nb->dev->type) {
 205         case ARPHRD_X25:
 206                 dptr  = skb_push(skb, 1);
 207                 *dptr = X25_IFACE_DATA;
 208                 break;
 209
 210 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
 211         case ARPHRD_ETHER:
 212                 kfree_skb(skb);
 213                 return;
 214 #endif
 215         default:
 216                 kfree_skb(skb);
 217                 return;
 218         }
 219
 220         skb->protocol = htons(ETH_P_X25);
 221         skb->dev      = nb->dev;
 222
 223         dev_queue_xmit(skb);
 224 }