LXR linux/net/lapb/lapb

   1/*
   2 *      LAPB release 002
   3 *
   4 *      This code REQUIRES 2.1.15 or higher/ NET3.038
   5 *
   6 *      This module:
   7 *              This module is free software; you can redistribute it and/or
   8 *              modify it under the terms of the GNU General Public License
   9 *              as published by the Free Software Foundation; either version
  10 *              2 of the License, or (at your option) any later version.
  11 *
  12 *      History
  13 *      LAPB 001        Jonathan Naylor Started Coding
  14 */
  15
  16#include <linux/errno.h>
  17#include <linux/types.h>
  18#include <linux/socket.h>
  19#include <linux/in.h>
  20#include <linux/kernel.h>
  21#include <linux/timer.h>
  22#include <linux/string.h>
  23#include <linux/sockios.h>
  24#include <linux/net.h>
  25#include <linux/inet.h>
  26#include <linux/skbuff.h>
  27#include <linux/slab.h>
  28#include <net/sock.h>
  29#include <asm/uaccess.h>
  30#include <asm/system.h>
  31#include <linux/fcntl.h>
  32#include <linux/mm.h>
  33#include <linux/interrupt.h>
  34#include <net/lapb.h>
  35
  36/*
  37 *      This routine purges all the queues of frames.
  38 */
  39void lapb_clear_queues(struct lapb_cb *lapb)
  40{
  41        skb_queue_purge(&lapb->write_queue);
  42        skb_queue_purge(&lapb->ack_queue);
  43}
  44
  45/*
  46 * This routine purges the input queue of those frames that have been
  47 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
  48 * SDL diagram.
  49 */
  50void lapb_frames_acked(struct lapb_cb *lapb, unsigned short nr)
  51{
  52        struct sk_buff *skb;
  53        int modulus;
  54
  55        modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
  56
  57        /*
  58         * Remove all the ack-ed frames from the ack queue.
  59         */
  60        if (lapb->va != nr)
  61                while (skb_peek(&lapb->ack_queue) && lapb->va != nr) {
  62                        skb = skb_dequeue(&lapb->ack_queue);
  63                        kfree_skb(skb);
  64                        lapb->va = (lapb->va + 1) % modulus;
  65                }
  66}
  67
  68void lapb_requeue_frames(struct lapb_cb *lapb)
  69{
  70        struct sk_buff *skb, *skb_prev = NULL;
  71
  72        /*
  73         * Requeue all the un-ack-ed frames on the output queue to be picked
  74         * up by lapb_kick called from the timer. This arrangement handles the
  75         * possibility of an empty output queue.
  76         */
  77        while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) {
  78                if (!skb_prev)
  79                        skb_queue_head(&lapb->write_queue, skb);
  80                else
  81                        skb_append(skb_prev, skb, &lapb->write_queue);
  82                skb_prev = skb;
  83        }
  84}
  85
  86/*
  87 *      Validate that the value of nr is between va and vs. Return true or
  88 *      false for testing.
  89 */
  90int lapb_validate_nr(struct lapb_cb *lapb, unsigned short nr)
  91{
  92        unsigned short vc = lapb->va;
  93        int modulus;
  94
  95        modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
  96
  97        while (vc != lapb->vs) {
  98                if (nr == vc)
  99                        return 1;
 100                vc = (vc + 1) % modulus;
 101        }
 102
 103        return nr == lapb->vs;
 104}
 105
 106/*
 107 *      This routine is the centralised routine for parsing the control
 108 *      information for the different frame formats.
 109 */
 110int lapb_decode(struct lapb_cb *lapb, struct sk_buff *skb,
 111                struct lapb_frame *frame)
 112{
 113        frame->type = LAPB_ILLEGAL;
 114
 115#if LAPB_DEBUG > 2
 116        printk(KERN_DEBUG "lapb: (%p) S%d RX %02X %02X %02X\n",
 117               lapb->dev, lapb->state,
 118               skb->data[0], skb->data[1], skb->data[2]);
 119#endif
 120
 121        /* We always need to look at 2 bytes, sometimes we need
 122         * to look at 3 and those cases are handled below.
 123         */
 124        if (!pskb_may_pull(skb, 2))
 125                return -1;
 126
 127        if (lapb->mode & LAPB_MLP) {
 128                if (lapb->mode & LAPB_DCE) {
 129                        if (skb->data[0] == LAPB_ADDR_D)
 130                                frame->cr = LAPB_COMMAND;
 131                        if (skb->data[0] == LAPB_ADDR_C)
 132                                frame->cr = LAPB_RESPONSE;
 133                } else {
 134                        if (skb->data[0] == LAPB_ADDR_C)
 135                                frame->cr = LAPB_COMMAND;
 136                        if (skb->data[0] == LAPB_ADDR_D)
 137                                frame->cr = LAPB_RESPONSE;
 138                }
 139        } else {
 140                if (lapb->mode & LAPB_DCE) {
 141                        if (skb->data[0] == LAPB_ADDR_B)
 142                                frame->cr = LAPB_COMMAND;
 143                        if (skb->data[0] == LAPB_ADDR_A)
 144                                frame->cr = LAPB_RESPONSE;
 145                } else {
 146                        if (skb->data[0] == LAPB_ADDR_A)
 147                                frame->cr = LAPB_COMMAND;
 148                        if (skb->data[0] == LAPB_ADDR_B)
 149                                frame->cr = LAPB_RESPONSE;
 150                }
 151        }
 152
 153        skb_pull(skb, 1);
 154
 155        if (lapb->mode & LAPB_EXTENDED) {
 156                if (!(skb->data[0] & LAPB_S)) {
 157                        if (!pskb_may_pull(skb, 2))
 158                                return -1;
 159                        /*
 160                         * I frame - carries NR/NS/PF
 161                         */
 162                        frame->type       = LAPB_I;
 163                        frame->ns         = (skb->data[0] >> 1) & 0x7F;
 164                        frame->nr         = (skb->data[1] >> 1) & 0x7F;
 165                        frame->pf         = skb->data[1] & LAPB_EPF;
 166                        frame->control[0] = skb->data[0];
 167                        frame->control[1] = skb->data[1];
 168                        skb_pull(skb, 2);
 169                } else if ((skb->data[0] & LAPB_U) == 1) {
 170                        if (!pskb_may_pull(skb, 2))
 171                                return -1;
 172                        /*
 173                         * S frame - take out PF/NR
 174                         */
 175                        frame->type       = skb->data[0] & 0x0F;
 176                        frame->nr         = (skb->data[1] >> 1) & 0x7F;
 177                        frame->pf         = skb->data[1] & LAPB_EPF;
 178                        frame->control[0] = skb->data[0];
 179                        frame->control[1] = skb->data[1];
 180                        skb_pull(skb, 2);
 181                } else if ((skb->data[0] & LAPB_U) == 3) {
 182                        /*
 183                         * U frame - take out PF
 184                         */
 185                        frame->type       = skb->data[0] & ~LAPB_SPF;
 186                        frame->pf         = skb->data[0] & LAPB_SPF;
 187                        frame->control[0] = skb->data[0];
 188                        frame->control[1] = 0x00;
 189                        skb_pull(skb, 1);
 190                }
 191        } else {
 192                if (!(skb->data[0] & LAPB_S)) {
 193                        /*
 194                         * I frame - carries NR/NS/PF
 195                         */
 196                        frame->type = LAPB_I;
 197                        frame->ns   = (skb->data[0] >> 1) & 0x07;
 198                        frame->nr   = (skb->data[0] >> 5) & 0x07;
 199                        frame->pf   = skb->data[0] & LAPB_SPF;
 200                } else if ((skb->data[0] & LAPB_U) == 1) {
 201                        /*
 202                         * S frame - take out PF/NR
 203                         */
 204                        frame->type = skb->data[0] & 0x0F;
 205                        frame->nr   = (skb->data[0] >> 5) & 0x07;
 206                        frame->pf   = skb->data[0] & LAPB_SPF;
 207                } else if ((skb->data[0] & LAPB_U) == 3) {
 208                        /*
 209                         * U frame - take out PF
 210                         */
 211                        frame->type = skb->data[0] & ~LAPB_SPF;
 212                        frame->pf   = skb->data[0] & LAPB_SPF;
 213                }
 214
 215                frame->control[0] = skb->data[0];
 216
 217                skb_pull(skb, 1);
 218        }
 219
 220        return 0;
 221}
 222
 223/*
 224 *      This routine is called when the HDLC layer internally  generates a
 225 *      command or  response  for  the remote machine ( eg. RR, UA etc. ).
 226 *      Only supervisory or unnumbered frames are processed, FRMRs are handled
 227 *      by lapb_transmit_frmr below.
 228 */
 229void lapb_send_control(struct lapb_cb *lapb, int frametype,
 230                       int poll_bit, int type)
 231{
 232        struct sk_buff *skb;
 233        unsigned char  *dptr;
 234
 235        if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL)
 236                return;
 237
 238        skb_reserve(skb, LAPB_HEADER_LEN + 1);
 239
 240        if (lapb->mode & LAPB_EXTENDED) {
 241                if ((frametype & LAPB_U) == LAPB_U) {
 242                        dptr   = skb_put(skb, 1);
 243                        *dptr  = frametype;
 244                        *dptr |= poll_bit ? LAPB_SPF : 0;
 245                } else {
 246                        dptr     = skb_put(skb, 2);
 247                        dptr[0]  = frametype;
 248                        dptr[1]  = (lapb->vr << 1);
 249                        dptr[1] |= poll_bit ? LAPB_EPF : 0;
 250                }
 251        } else {
 252                dptr   = skb_put(skb, 1);
 253                *dptr  = frametype;
 254                *dptr |= poll_bit ? LAPB_SPF : 0;
 255                if ((frametype & LAPB_U) == LAPB_S)     /* S frames carry NR */
 256                        *dptr |= (lapb->vr << 5);
 257        }
 258
 259        lapb_transmit_buffer(lapb, skb, type);
 260}
 261
 262/*
 263 *      This routine generates FRMRs based on information previously stored in
 264 *      the LAPB control block.
 265 */
 266void lapb_transmit_frmr(struct lapb_cb *lapb)
 267{
 268        struct sk_buff *skb;
 269        unsigned char  *dptr;
 270
 271        if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL)
 272                return;
 273
 274        skb_reserve(skb, LAPB_HEADER_LEN + 1);
 275
 276        if (lapb->mode & LAPB_EXTENDED) {
 277                dptr    = skb_put(skb, 6);
 278                *dptr++ = LAPB_FRMR;
 279                *dptr++ = lapb->frmr_data.control[0];
 280                *dptr++ = lapb->frmr_data.control[1];
 281                *dptr++ = (lapb->vs << 1) & 0xFE;
 282                *dptr   = (lapb->vr << 1) & 0xFE;
 283                if (lapb->frmr_data.cr == LAPB_RESPONSE)
 284                        *dptr |= 0x01;
 285                dptr++;
 286                *dptr++ = lapb->frmr_type;
 287
 288#if LAPB_DEBUG > 1
 289        printk(KERN_DEBUG "lapb: (%p) S%d TX FRMR %02X %02X %02X %02X %02X\n",
 290               lapb->dev, lapb->state,
 291               skb->data[1], skb->data[2], skb->data[3],
 292               skb->data[4], skb->data[5]);
 293#endif
 294        } else {
 295                dptr    = skb_put(skb, 4);
 296                *dptr++ = LAPB_FRMR;
 297                *dptr++ = lapb->frmr_data.control[0];
 298                *dptr   = (lapb->vs << 1) & 0x0E;
 299                *dptr  |= (lapb->vr << 5) & 0xE0;
 300                if (lapb->frmr_data.cr == LAPB_RESPONSE)
 301                        *dptr |= 0x10;
 302                dptr++;
 303                *dptr++ = lapb->frmr_type;
 304
 305#if LAPB_DEBUG > 1
 306        printk(KERN_DEBUG "lapb: (%p) S%d TX FRMR %02X %02X %02X\n",
 307               lapb->dev, lapb->state, skb->data[1],
 308               skb->data[2], skb->data[3]);
 309#endif
 310        }
 311
 312        lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE);
 313}
 314