linux/net/x25/x25_link.c
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   1/*
   2 *      X.25 Packet Layer release 002
   3 *
   4 *      This is ALPHA test software. This code may break your machine,
   5 *      randomly fail to work with new releases, misbehave and/or generally
   6 *      screw up. It might even work.
   7 *
   8 *      This code REQUIRES 2.1.15 or higher
   9 *
  10 *      This module:
  11 *              This module is free software; you can redistribute it and/or
  12 *              modify it under the terms of the GNU General Public License
  13 *              as published by the Free Software Foundation; either version
  14 *              2 of the License, or (at your option) any later version.
  15 *
  16 *      History
  17 *      X.25 001        Jonathan Naylor   Started coding.
  18 *      X.25 002        Jonathan Naylor   New timer architecture.
  19 *      mar/20/00       Daniela Squassoni Disabling/enabling of facilities
  20 *                                        negotiation.
  21 *      2000-09-04      Henner Eisen      dev_hold() / dev_put() for x25_neigh.
  22 */
  23
  24#include <linux/kernel.h>
  25#include <linux/jiffies.h>
  26#include <linux/timer.h>
  27#include <linux/slab.h>
  28#include <linux/netdevice.h>
  29#include <linux/skbuff.h>
  30#include <asm/uaccess.h>
  31#include <linux/init.h>
  32#include <net/x25.h>
  33
  34LIST_HEAD(x25_neigh_list);
  35DEFINE_RWLOCK(x25_neigh_list_lock);
  36
  37static void x25_t20timer_expiry(unsigned long);
  38
  39static void x25_transmit_restart_confirmation(struct x25_neigh *nb);
  40static void x25_transmit_restart_request(struct x25_neigh *nb);
  41
  42/*
  43 *      Linux set/reset timer routines
  44 */
  45static inline void x25_start_t20timer(struct x25_neigh *nb)
  46{
  47        mod_timer(&nb->t20timer, jiffies + nb->t20);
  48}
  49
  50static void x25_t20timer_expiry(unsigned long param)
  51{
  52        struct x25_neigh *nb = (struct x25_neigh *)param;
  53
  54        x25_transmit_restart_request(nb);
  55
  56        x25_start_t20timer(nb);
  57}
  58
  59static inline void x25_stop_t20timer(struct x25_neigh *nb)
  60{
  61        del_timer(&nb->t20timer);
  62}
  63
  64static inline int x25_t20timer_pending(struct x25_neigh *nb)
  65{
  66        return timer_pending(&nb->t20timer);
  67}
  68
  69/*
  70 *      This handles all restart and diagnostic frames.
  71 */
  72void x25_link_control(struct sk_buff *skb, struct x25_neigh *nb,
  73                      unsigned short frametype)
  74{
  75        struct sk_buff *skbn;
  76        int confirm;
  77
  78        switch (frametype) {
  79        case X25_RESTART_REQUEST:
  80                confirm = !x25_t20timer_pending(nb);
  81                x25_stop_t20timer(nb);
  82                nb->state = X25_LINK_STATE_3;
  83                if (confirm)
  84                        x25_transmit_restart_confirmation(nb);
  85                break;
  86
  87        case X25_RESTART_CONFIRMATION:
  88                x25_stop_t20timer(nb);
  89                nb->state = X25_LINK_STATE_3;
  90                break;
  91
  92        case X25_DIAGNOSTIC:
  93                if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 4))
  94                        break;
  95
  96                printk(KERN_WARNING "x25: diagnostic #%d - %02X %02X %02X\n",
  97                       skb->data[3], skb->data[4],
  98                       skb->data[5], skb->data[6]);
  99                break;
 100
 101        default:
 102                printk(KERN_WARNING "x25: received unknown %02X with LCI 000\n",
 103                       frametype);
 104                break;
 105        }
 106
 107        if (nb->state == X25_LINK_STATE_3)
 108                while ((skbn = skb_dequeue(&nb->queue)) != NULL)
 109                        x25_send_frame(skbn, nb);
 110}
 111
 112/*
 113 *      This routine is called when a Restart Request is needed
 114 */
 115static void x25_transmit_restart_request(struct x25_neigh *nb)
 116{
 117        unsigned char *dptr;
 118        int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
 119        struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 120
 121        if (!skb)
 122                return;
 123
 124        skb_reserve(skb, X25_MAX_L2_LEN);
 125
 126        dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
 127
 128        *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
 129        *dptr++ = 0x00;
 130        *dptr++ = X25_RESTART_REQUEST;
 131        *dptr++ = 0x00;
 132        *dptr++ = 0;
 133
 134        skb->sk = NULL;
 135
 136        x25_send_frame(skb, nb);
 137}
 138
 139/*
 140 * This routine is called when a Restart Confirmation is needed
 141 */
 142static void x25_transmit_restart_confirmation(struct x25_neigh *nb)
 143{
 144        unsigned char *dptr;
 145        int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN;
 146        struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 147
 148        if (!skb)
 149                return;
 150
 151        skb_reserve(skb, X25_MAX_L2_LEN);
 152
 153        dptr = skb_put(skb, X25_STD_MIN_LEN);
 154
 155        *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
 156        *dptr++ = 0x00;
 157        *dptr++ = X25_RESTART_CONFIRMATION;
 158
 159        skb->sk = NULL;
 160
 161        x25_send_frame(skb, nb);
 162}
 163
 164/*
 165 *      This routine is called when a Clear Request is needed outside of the context
 166 *      of a connected socket.
 167 */
 168void x25_transmit_clear_request(struct x25_neigh *nb, unsigned int lci,
 169                                unsigned char cause)
 170{
 171        unsigned char *dptr;
 172        int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
 173        struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 174
 175        if (!skb)
 176                return;
 177
 178        skb_reserve(skb, X25_MAX_L2_LEN);
 179
 180        dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
 181
 182        *dptr++ = ((lci >> 8) & 0x0F) | (nb->extended ?
 183                                         X25_GFI_EXTSEQ :
 184                                         X25_GFI_STDSEQ);
 185        *dptr++ = (lci >> 0) & 0xFF;
 186        *dptr++ = X25_CLEAR_REQUEST;
 187        *dptr++ = cause;
 188        *dptr++ = 0x00;
 189
 190        skb->sk = NULL;
 191
 192        x25_send_frame(skb, nb);
 193}
 194
 195void x25_transmit_link(struct sk_buff *skb, struct x25_neigh *nb)
 196{
 197        switch (nb->state) {
 198        case X25_LINK_STATE_0:
 199                skb_queue_tail(&nb->queue, skb);
 200                nb->state = X25_LINK_STATE_1;
 201                x25_establish_link(nb);
 202                break;
 203        case X25_LINK_STATE_1:
 204        case X25_LINK_STATE_2:
 205                skb_queue_tail(&nb->queue, skb);
 206                break;
 207        case X25_LINK_STATE_3:
 208                x25_send_frame(skb, nb);
 209                break;
 210        }
 211}
 212
 213/*
 214 *      Called when the link layer has become established.
 215 */
 216void x25_link_established(struct x25_neigh *nb)
 217{
 218        switch (nb->state) {
 219        case X25_LINK_STATE_0:
 220                nb->state = X25_LINK_STATE_2;
 221                break;
 222        case X25_LINK_STATE_1:
 223                x25_transmit_restart_request(nb);
 224                nb->state = X25_LINK_STATE_2;
 225                x25_start_t20timer(nb);
 226                break;
 227        }
 228}
 229
 230/*
 231 *      Called when the link layer has terminated, or an establishment
 232 *      request has failed.
 233 */
 234
 235void x25_link_terminated(struct x25_neigh *nb)
 236{
 237        nb->state = X25_LINK_STATE_0;
 238        /* Out of order: clear existing virtual calls (X.25 03/93 4.6.3) */
 239        x25_kill_by_neigh(nb);
 240}
 241
 242/*
 243 *      Add a new device.
 244 */
 245void x25_link_device_up(struct net_device *dev)
 246{
 247        struct x25_neigh *nb = kmalloc(sizeof(*nb), GFP_ATOMIC);
 248
 249        if (!nb)
 250                return;
 251
 252        skb_queue_head_init(&nb->queue);
 253        setup_timer(&nb->t20timer, x25_t20timer_expiry, (unsigned long)nb);
 254
 255        dev_hold(dev);
 256        nb->dev      = dev;
 257        nb->state    = X25_LINK_STATE_0;
 258        nb->extended = 0;
 259        /*
 260         * Enables negotiation
 261         */
 262        nb->global_facil_mask = X25_MASK_REVERSE |
 263                                       X25_MASK_THROUGHPUT |
 264                                       X25_MASK_PACKET_SIZE |
 265                                       X25_MASK_WINDOW_SIZE;
 266        nb->t20      = sysctl_x25_restart_request_timeout;
 267        atomic_set(&nb->refcnt, 1);
 268
 269        write_lock_bh(&x25_neigh_list_lock);
 270        list_add(&nb->node, &x25_neigh_list);
 271        write_unlock_bh(&x25_neigh_list_lock);
 272}
 273
 274/**
 275 *      __x25_remove_neigh - remove neighbour from x25_neigh_list
 276 *      @nb - neigh to remove
 277 *
 278 *      Remove neighbour from x25_neigh_list. If it was there.
 279 *      Caller must hold x25_neigh_list_lock.
 280 */
 281static void __x25_remove_neigh(struct x25_neigh *nb)
 282{
 283        skb_queue_purge(&nb->queue);
 284        x25_stop_t20timer(nb);
 285
 286        if (nb->node.next) {
 287                list_del(&nb->node);
 288                x25_neigh_put(nb);
 289        }
 290}
 291
 292/*
 293 *      A device has been removed, remove its links.
 294 */
 295void x25_link_device_down(struct net_device *dev)
 296{
 297        struct x25_neigh *nb;
 298        struct list_head *entry, *tmp;
 299
 300        write_lock_bh(&x25_neigh_list_lock);
 301
 302        list_for_each_safe(entry, tmp, &x25_neigh_list) {
 303                nb = list_entry(entry, struct x25_neigh, node);
 304
 305                if (nb->dev == dev) {
 306                        __x25_remove_neigh(nb);
 307                        dev_put(dev);
 308                }
 309        }
 310
 311        write_unlock_bh(&x25_neigh_list_lock);
 312}
 313
 314/*
 315 *      Given a device, return the neighbour address.
 316 */
 317struct x25_neigh *x25_get_neigh(struct net_device *dev)
 318{
 319        struct x25_neigh *nb, *use = NULL;
 320        struct list_head *entry;
 321
 322        read_lock_bh(&x25_neigh_list_lock);
 323        list_for_each(entry, &x25_neigh_list) {
 324                nb = list_entry(entry, struct x25_neigh, node);
 325
 326                if (nb->dev == dev) {
 327                        use = nb;
 328                        break;
 329                }
 330        }
 331
 332        if (use)
 333                x25_neigh_hold(use);
 334        read_unlock_bh(&x25_neigh_list_lock);
 335        return use;
 336}
 337
 338/*
 339 *      Handle the ioctls that control the subscription functions.
 340 */
 341int x25_subscr_ioctl(unsigned int cmd, void __user *arg)
 342{
 343        struct x25_subscrip_struct x25_subscr;
 344        struct x25_neigh *nb;
 345        struct net_device *dev;
 346        int rc = -EINVAL;
 347
 348        if (cmd != SIOCX25GSUBSCRIP && cmd != SIOCX25SSUBSCRIP)
 349                goto out;
 350
 351        rc = -EFAULT;
 352        if (copy_from_user(&x25_subscr, arg, sizeof(x25_subscr)))
 353                goto out;
 354
 355        rc = -EINVAL;
 356        if ((dev = x25_dev_get(x25_subscr.device)) == NULL)
 357                goto out;
 358
 359        if ((nb = x25_get_neigh(dev)) == NULL)
 360                goto out_dev_put;
 361
 362        dev_put(dev);
 363
 364        if (cmd == SIOCX25GSUBSCRIP) {
 365                read_lock_bh(&x25_neigh_list_lock);
 366                x25_subscr.extended          = nb->extended;
 367                x25_subscr.global_facil_mask = nb->global_facil_mask;
 368                read_unlock_bh(&x25_neigh_list_lock);
 369                rc = copy_to_user(arg, &x25_subscr,
 370                                  sizeof(x25_subscr)) ? -EFAULT : 0;
 371        } else {
 372                rc = -EINVAL;
 373                if (!(x25_subscr.extended && x25_subscr.extended != 1)) {
 374                        rc = 0;
 375                        write_lock_bh(&x25_neigh_list_lock);
 376                        nb->extended         = x25_subscr.extended;
 377                        nb->global_facil_mask = x25_subscr.global_facil_mask;
 378                        write_unlock_bh(&x25_neigh_list_lock);
 379                }
 380        }
 381        x25_neigh_put(nb);
 382out:
 383        return rc;
 384out_dev_put:
 385        dev_put(dev);
 386        goto out;
 387}
 388
 389
 390/*
 391 *      Release all memory associated with X.25 neighbour structures.
 392 */
 393void __exit x25_link_free(void)
 394{
 395        struct x25_neigh *nb;
 396        struct list_head *entry, *tmp;
 397
 398        write_lock_bh(&x25_neigh_list_lock);
 399
 400        list_for_each_safe(entry, tmp, &x25_neigh_list) {
 401                struct net_device *dev;
 402
 403                nb = list_entry(entry, struct x25_neigh, node);
 404                dev = nb->dev;
 405                __x25_remove_neigh(nb);
 406                dev_put(dev);
 407        }
 408        write_unlock_bh(&x25_neigh_list_lock);
 409}
 410
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