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         .proto_new = &isdn_x25iface_proto_new,
  57         .proto_del = &isdn_x25iface_proto_del,
  58         .restart = &isdn_x25iface_proto_restart,
  59         .close = &isdn_x25iface_proto_close,
  60         .encap_and_xmit = &isdn_x25iface_xmit,
  61         .data_ind = &isdn_x25iface_receive,
  62         .connect_ind = &isdn_x25iface_connect_ind,
  63         .disconn_ind = &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] = 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  */
 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_u8(skb, 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  */
 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_u8(skb, 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 */
 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",
 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                         netif_trans_update(cprot->net_dev);
 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 }