drivers/isdn/i4l/isdn_x25iface.c

   1 /* $Id: isdn_x25iface.c,v 1.1.2.2 2004/01/12 22:37:19 keil Exp $
   2  *
   3  * Linux ISDN subsystem, X.25 related functions
   4  *
   5  * This software may be used and distributed according to the terms
   6  * of the GNU General Public License, incorporated herein by reference.
   7  *
   8  * stuff needed to support the Linux X.25 PLP code on top of devices that
   9  * can provide a lab_b service using the concap_proto mechanism.
  10  * This module supports a network interface which provides lapb_sematics
  11  * -- as defined in Documentation/networking/x25-iface.txt -- to
  12  * the upper layer and assumes that the lower layer provides a reliable
  13  * data link service by means of the concap_device_ops callbacks.
  14  *
  15  * Only protocol specific stuff goes here. Device specific stuff
  16  * goes to another -- device related -- concap_proto support source file.
  17  *
  18  */
  19
  20 /* #include <linux/isdn.h> */
  21 #include <linux/netdevice.h>
  22 #include <linux/concap.h>
  23 #include <linux/slab.h>
  24 #include <linux/wanrouter.h>
  25 #include <net/x25device.h>
  26 #include "isdn_x25iface.h"
  27
  28 /* for debugging messages not to cause an oops when device pointer is NULL*/
  29 #define MY_DEVNAME(dev)  ( (dev) ? (dev)->name : "DEVICE UNSPECIFIED" )
  30
  31
  32 typedef struct isdn_x25iface_proto_data {
  33         int magic;
  34         enum wan_states state;
  35         /* Private stuff, not to be accessed via proto_data. We provide the
  36            other storage for the concap_proto instance here as well,
  37            enabling us to allocate both with just one kmalloc(): */
  38         struct concap_proto priv;
  39 } ix25_pdata_t;
  40
  41
  42
  43 /* is now in header file (extern): struct concap_proto * isdn_x25iface_proto_new(void); */
  44 static void isdn_x25iface_proto_del( struct concap_proto * );
  45 static int isdn_x25iface_proto_close( struct concap_proto * );
  46 static int isdn_x25iface_proto_restart( struct concap_proto *,
  47                                         struct net_device *,
  48                                         struct concap_device_ops *);
  49 static int isdn_x25iface_xmit( struct concap_proto *, struct sk_buff * );
  50 static int isdn_x25iface_receive( struct concap_proto *, struct sk_buff * );
  51 static int isdn_x25iface_connect_ind( struct concap_proto * );
  52 static int isdn_x25iface_disconn_ind( struct concap_proto * );
  53
  54
  55 static struct concap_proto_ops ix25_pops = {
  56         &isdn_x25iface_proto_new,
  57         &isdn_x25iface_proto_del,
  58         &isdn_x25iface_proto_restart,
  59         &isdn_x25iface_proto_close,
  60         &isdn_x25iface_xmit,
  61         &isdn_x25iface_receive,
  62         &isdn_x25iface_connect_ind,
  63         &isdn_x25iface_disconn_ind
  64 };
  65
  66 /* error message helper function */
  67 static void illegal_state_warn( unsigned state, unsigned char firstbyte)
  68 {
  69         printk( KERN_WARNING "isdn_x25iface: firstbyte %x illegal in"
  70                 "current state %d\n",firstbyte, state );
  71 }
  72
  73 /* check protocol data field for consistency */
  74 static int pdata_is_bad( ix25_pdata_t * pda ){
  75
  76         if( pda  &&  pda -> magic == ISDN_X25IFACE_MAGIC ) return 0;
  77         printk( KERN_WARNING
  78                 "isdn_x25iface_xxx: illegal pointer to proto data\n" );
  79         return 1;
  80 }
  81
  82 /* create a new x25 interface protocol instance
  83  */
  84 struct concap_proto * isdn_x25iface_proto_new(void)
  85 {
  86         ix25_pdata_t * tmp = kmalloc(sizeof(ix25_pdata_t),GFP_KERNEL);
  87         IX25DEBUG("isdn_x25iface_proto_new\n");
  88         if( tmp ){
  89                 tmp -> magic = ISDN_X25IFACE_MAGIC;
  90                 tmp -> state = WAN_UNCONFIGURED;
  91                 /* private data space used to hold the concap_proto data.
  92                    Only to be accessed via the returned pointer */
  93                 spin_lock_init(&tmp->priv.lock);
  94                 tmp -> priv.dops       = NULL;
  95                 tmp -> priv.net_dev    = NULL;
  96                 tmp -> priv.pops       = &ix25_pops;
  97                 tmp -> priv.flags      = 0;
  98                 tmp -> priv.proto_data = tmp;
  99                 return( &(tmp -> priv) );
 100         }
 101         return NULL;
 102 };
 103
 104 /* close the x25iface encapsulation protocol
 105  */
 106 static int isdn_x25iface_proto_close(struct concap_proto *cprot){
 107
 108         ix25_pdata_t *tmp;
 109         int ret = 0;
 110         ulong flags;
 111
 112         if( ! cprot ){
 113                 printk( KERN_ERR "isdn_x25iface_proto_close: "
 114                         "invalid concap_proto pointer\n" );
 115                 return -1;
 116         }
 117         IX25DEBUG( "isdn_x25iface_proto_close %s \n", MY_DEVNAME(cprot -> net_dev) );
 118         spin_lock_irqsave(&cprot->lock, flags);
 119         cprot -> dops    = NULL;
 120         cprot -> net_dev = NULL;
 121         tmp = cprot -> proto_data;
 122         if( pdata_is_bad( tmp ) ){
 123                 ret = -1;
 124         } else {
 125                 tmp -> state = WAN_UNCONFIGURED;
 126         }
 127         spin_unlock_irqrestore(&cprot->lock, flags);
 128         return ret;
 129 }
 130
 131 /* Delete the x25iface encapsulation protocol instance
 132  */
 133 static void isdn_x25iface_proto_del(struct concap_proto *cprot){
 134
 135         ix25_pdata_t * tmp;
 136
 137         IX25DEBUG( "isdn_x25iface_proto_del \n" );
 138         if( ! cprot ){
 139                 printk( KERN_ERR "isdn_x25iface_proto_del: "
 140                         "concap_proto pointer is NULL\n" );
 141                 return;
 142         }
 143         tmp = cprot -> proto_data;
 144         if( tmp == NULL ){
 145                 printk( KERN_ERR "isdn_x25iface_proto_del: inconsistent "
 146                         "proto_data pointer (maybe already deleted?)\n");
 147                 return;
 148         }
 149         /* close if the protocol is still open */
 150         if( cprot -> dops ) isdn_x25iface_proto_close(cprot);
 151         /* freeing the storage should be sufficient now. But some additional
 152            settings might help to catch wild pointer bugs */
 153         tmp -> magic = 0;
 154         cprot -> proto_data = NULL;
 155
 156         kfree( tmp );
 157         return;
 158 }
 159
 160 /* (re-)initialize the data structures for x25iface encapsulation
 161  */
 162 static int isdn_x25iface_proto_restart(struct concap_proto *cprot,
 163                                         struct net_device *ndev,
 164                                         struct concap_device_ops *dops)
 165 {
 166         ix25_pdata_t * pda = cprot -> proto_data ;
 167         ulong flags;
 168
 169         IX25DEBUG( "isdn_x25iface_proto_restart %s \n", MY_DEVNAME(ndev) );
 170
 171         if ( pdata_is_bad( pda ) ) return -1;
 172
 173         if( !( dops  && dops -> data_req && dops -> connect_req
 174                && dops -> disconn_req )  ){
 175                 printk( KERN_WARNING "isdn_x25iface_restart: required dops"
 176                         " missing\n" );
 177                 isdn_x25iface_proto_close(cprot);
 178                 return -1;
 179         }
 180         spin_lock_irqsave(&cprot->lock, flags);
 181         cprot -> net_dev = ndev;
 182         cprot -> pops = &ix25_pops;
 183         cprot -> dops = dops;
 184         pda -> state = WAN_DISCONNECTED;
 185         spin_unlock_irqrestore(&cprot->lock, flags);
 186         return 0;
 187 }
 188
 189 /* deliver a dl_data frame received from i4l HL driver to the network layer
 190  */
 191 static int isdn_x25iface_receive(struct concap_proto *cprot, struct sk_buff *skb)
 192 {
 193         IX25DEBUG( "isdn_x25iface_receive %s \n", MY_DEVNAME(cprot->net_dev) );
 194         if ( ( (ix25_pdata_t*) (cprot->proto_data) )
 195              -> state == WAN_CONNECTED ){
 196                 if( skb_push(skb, 1)){
 197                         skb -> data[0]=0x00;
 198                         skb->protocol = x25_type_trans(skb, cprot->net_dev);
 199                         netif_rx(skb);
 200                         return 0;
 201                 }
 202         }
 203         printk(KERN_WARNING "isdn_x25iface_receive %s: not connected, skb dropped\n", MY_DEVNAME(cprot->net_dev) );
 204         dev_kfree_skb(skb);
 205         return -1;
 206 }
 207
 208 /* a connection set up is indicated by lower layer
 209  */
 210 static int isdn_x25iface_connect_ind(struct concap_proto *cprot)
 211 {
 212         struct sk_buff * skb;
 213         enum wan_states *state_p
 214           = &( ( (ix25_pdata_t*) (cprot->proto_data) ) -> state);
 215         IX25DEBUG( "isdn_x25iface_connect_ind %s \n"
 216                    , MY_DEVNAME(cprot->net_dev) );
 217         if( *state_p == WAN_UNCONFIGURED ){
 218                 printk(KERN_WARNING
 219                        "isdn_x25iface_connect_ind while unconfigured %s\n"
 220                        , MY_DEVNAME(cprot->net_dev) );
 221                 return -1;
 222         }
 223         *state_p = WAN_CONNECTED;
 224
 225         skb = dev_alloc_skb(1);
 226         if( skb ){
 227                 *( skb_put(skb, 1) ) = 0x01;
 228                 skb->protocol = x25_type_trans(skb, cprot->net_dev);
 229                 netif_rx(skb);
 230                 return 0;
 231         } else {
 232                 printk(KERN_WARNING "isdn_x25iface_connect_ind: "
 233                        " out of memory -- disconnecting\n");
 234                 cprot -> dops -> disconn_req(cprot);
 235                 return -1;
 236         }
 237 }
 238
 239 /* a disconnect is indicated by lower layer
 240  */
 241 static int isdn_x25iface_disconn_ind(struct concap_proto *cprot)
 242 {
 243         struct sk_buff *skb;
 244         enum wan_states *state_p
 245           = &( ( (ix25_pdata_t*) (cprot->proto_data) ) -> state);
 246         IX25DEBUG( "isdn_x25iface_disconn_ind %s \n", MY_DEVNAME(cprot -> net_dev) );
 247         if( *state_p == WAN_UNCONFIGURED ){
 248                 printk(KERN_WARNING
 249                        "isdn_x25iface_disconn_ind while unconfigured\n");
 250                 return -1;
 251         }
 252         if(! cprot -> net_dev) return -1;
 253         *state_p = WAN_DISCONNECTED;
 254         skb = dev_alloc_skb(1);
 255         if( skb ){
 256                 *( skb_put(skb, 1) ) = 0x02;
 257                 skb->protocol = x25_type_trans(skb, cprot->net_dev);
 258                 netif_rx(skb);
 259                 return 0;
 260         } else {
 261                 printk(KERN_WARNING "isdn_x25iface_disconn_ind:"
 262                        " out of memory\n");
 263                 return -1;
 264         }
 265 }
 266
 267 /* process a frame handed over to us from linux network layer. First byte
 268    semantics as defined in Documentation/networking/x25-iface.txt
 269    */
 270 static int isdn_x25iface_xmit(struct concap_proto *cprot, struct sk_buff *skb)
 271 {
 272         unsigned char firstbyte = skb->data[0];
 273         enum wan_states *state = &((ix25_pdata_t*)cprot->proto_data)->state;
 274         int ret = 0;
 275         IX25DEBUG( "isdn_x25iface_xmit: %s first=%x state=%d \n", MY_DEVNAME(cprot -> net_dev), firstbyte, *state );
 276         switch ( firstbyte ){
 277         case 0x00: /* dl_data request */
 278                 if( *state == WAN_CONNECTED ){
 279                         skb_pull(skb, 1);
 280                         cprot -> net_dev -> trans_start = jiffies;
 281                         ret = ( cprot -> dops -> data_req(cprot, skb) );
 282                         /* prepare for future retransmissions */
 283                         if( ret ) skb_push(skb,1);
 284                         return ret;
 285                 }
 286                 illegal_state_warn( *state, firstbyte );
 287                 break;
 288         case 0x01: /* dl_connect request */
 289                 if( *state == WAN_DISCONNECTED ){
 290                         *state = WAN_CONNECTING;
 291                         ret = cprot -> dops -> connect_req(cprot);
 292                         if(ret){
 293                                 /* reset state and notify upper layer about
 294                                  * immidiatly failed attempts */
 295                                 isdn_x25iface_disconn_ind(cprot);
 296                         }
 297                 } else {
 298                         illegal_state_warn( *state, firstbyte );
 299                 }
 300                 break;
 301         case 0x02: /* dl_disconnect request */
 302                 switch ( *state ){
 303                 case WAN_DISCONNECTED:
 304                         /* Should not happen. However, give upper layer a
 305                            chance to recover from inconstistency  but don't
 306                            trust the lower layer sending the disconn_confirm
 307                            when already disconnected */
 308                         printk(KERN_WARNING "isdn_x25iface_xmit: disconnect "
 309                                " requested while disconnected\n" );
 310                         isdn_x25iface_disconn_ind(cprot);
 311                         break; /* prevent infinite loops */
 312                 case WAN_CONNECTING:
 313                 case WAN_CONNECTED:
 314                         *state = WAN_DISCONNECTED;
 315                         cprot -> dops -> disconn_req(cprot);
 316                         break;
 317                 default:
 318                         illegal_state_warn( *state, firstbyte );
 319                 }
 320                 break;
 321         case 0x03: /* changing lapb parameters requested */
 322                 printk(KERN_WARNING "isdn_x25iface_xmit: setting of lapb"
 323                        " options not yet supported\n");
 324                 break;
 325         default:
 326                 printk(KERN_WARNING "isdn_x25iface_xmit: frame with illegal"
 327                        " first byte %x ignored:\n", firstbyte);
 328         }
 329         dev_kfree_skb(skb);
 330         return 0;
 331 }