linux/drivers/isdn/i4l/isdn_x25iface.c
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   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
  32typedef 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); */
  44static void isdn_x25iface_proto_del( struct concap_proto * );
  45static int isdn_x25iface_proto_close( struct concap_proto * );
  46static int isdn_x25iface_proto_restart( struct concap_proto *,
  47                                        struct net_device *,
  48                                        struct concap_device_ops *);
  49static int isdn_x25iface_xmit( struct concap_proto *, struct sk_buff * );
  50static int isdn_x25iface_receive( struct concap_proto *, struct sk_buff * );
  51static int isdn_x25iface_connect_ind( struct concap_proto * );
  52static int isdn_x25iface_disconn_ind( struct concap_proto * );
  53
  54
  55static 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 */
  67static 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 */
  74static 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 */
  84struct 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 */
 106static 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 */
 133static 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 */
 162static 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 */
 191static 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] = X25_IFACE_DATA;
 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 */
 210static 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)) = X25_IFACE_CONNECT;
 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 */
 241static 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)) = X25_IFACE_DISCONNECT;
 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   */
 270static 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",
 276                MY_DEVNAME(cprot->net_dev), firstbyte, *state);
 277        switch ( firstbyte ){
 278        case X25_IFACE_DATA:
 279                if( *state == WAN_CONNECTED ){
 280                        skb_pull(skb, 1);
 281                        cprot -> net_dev -> trans_start = jiffies;
 282                        ret = ( cprot -> dops -> data_req(cprot, skb) );
 283                        /* prepare for future retransmissions */
 284                        if( ret ) skb_push(skb,1);
 285                        return ret;
 286                }
 287                illegal_state_warn( *state, firstbyte ); 
 288                break;
 289        case X25_IFACE_CONNECT:
 290                if( *state == WAN_DISCONNECTED ){
 291                        *state = WAN_CONNECTING;
 292                        ret = cprot -> dops -> connect_req(cprot);
 293                        if(ret){
 294                                /* reset state and notify upper layer about
 295                                 * immidiatly failed attempts */
 296                                isdn_x25iface_disconn_ind(cprot);
 297                        }
 298                } else {
 299                        illegal_state_warn( *state, firstbyte );
 300                }
 301                break;
 302        case X25_IFACE_DISCONNECT:
 303                switch ( *state ){
 304                case WAN_DISCONNECTED: 
 305                        /* Should not happen. However, give upper layer a
 306                           chance to recover from inconstistency  but don't
 307                           trust the lower layer sending the disconn_confirm
 308                           when already disconnected */
 309                        printk(KERN_WARNING "isdn_x25iface_xmit: disconnect "
 310                               " requested while disconnected\n" );
 311                        isdn_x25iface_disconn_ind(cprot);
 312                        break; /* prevent infinite loops */
 313                case WAN_CONNECTING:
 314                case WAN_CONNECTED:
 315                        *state = WAN_DISCONNECTED;
 316                        cprot -> dops -> disconn_req(cprot);
 317                        break;
 318                default:
 319                        illegal_state_warn( *state, firstbyte );
 320                }
 321                break;
 322        case X25_IFACE_PARAMS:
 323                printk(KERN_WARNING "isdn_x25iface_xmit: setting of lapb"
 324                       " options not yet supported\n");
 325                break;
 326        default:
 327                printk(KERN_WARNING "isdn_x25iface_xmit: frame with illegal"
 328                       " first byte %x ignored:\n", firstbyte);
 329        }
 330        dev_kfree_skb(skb);
 331        return 0;
 332}
 333