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