LXR linux-old/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/sched.h>
  22#include <linux/timer.h>
  23#include <linux/string.h>
  24#include <linux/sockios.h>
  25#include <linux/net.h>
  26#include <linux/inet.h>
  27#include <linux/skbuff.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(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(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) != NULL && lapb->va != nr) {
  62                        skb = skb_dequeue(&lapb->ack_queue);
  63                        kfree_skb(skb);
  64                        lapb->va = (lapb->va + 1) % modulus;
  65                }
  66        }
  67}
  68
  69void lapb_requeue_frames(lapb_cb *lapb)
  70{
  71        struct sk_buff *skb, *skb_prev = NULL;
  72
  73        /*
  74         * Requeue all the un-ack-ed frames on the output queue to be picked
  75         * up by lapb_kick called from the timer. This arrangement handles the
  76         * possibility of an empty output queue.
  77         */
  78        while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) {
  79                if (skb_prev == NULL)
  80                        skb_queue_head(&lapb->write_queue, skb);
  81                else
  82                        skb_append(skb_prev, skb);
  83                skb_prev = skb;
  84        }
  85}
  86
  87/*
  88 *      Validate that the value of nr is between va and vs. Return true or
  89 *      false for testing.
  90 */
  91int lapb_validate_nr(lapb_cb *lapb, unsigned short nr)
  92{
  93        unsigned short vc = lapb->va;
  94        int modulus;
  95        
  96        modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
  97
  98        while (vc != lapb->vs) {
  99                if (nr == vc) return 1;
 100                vc = (vc + 1) % modulus;
 101        }
 102        
 103        if (nr == lapb->vs) return 1;
 104
 105        return 0;
 106}
 107
 108/*
 109 *      This routine is the centralised routine for parsing the control
 110 *      information for the different frame formats.
 111 */
 112void lapb_decode(lapb_cb *lapb, struct sk_buff *skb, struct lapb_frame *frame)
 113{
 114        frame->type = LAPB_ILLEGAL;
 115
 116#if LAPB_DEBUG > 2
 117        printk(KERN_DEBUG "lapb: (%p) S%d RX %02X %02X %02X\n", lapb->token, lapb->state, skb->data[0], skb->data[1], skb->data[2]);
 118#endif
 119
 120        if (lapb->mode & LAPB_MLP) {
 121                if (lapb->mode & LAPB_DCE) {
 122                        if (skb->data[0] == LAPB_ADDR_D)
 123                                frame->cr = LAPB_COMMAND;
 124                        if (skb->data[0] == LAPB_ADDR_C)
 125                                frame->cr = LAPB_RESPONSE;
 126                } else {
 127                        if (skb->data[0] == LAPB_ADDR_C)
 128                                frame->cr = LAPB_COMMAND;
 129                        if (skb->data[0] == LAPB_ADDR_D)
 130                                frame->cr = LAPB_RESPONSE;
 131                }
 132        } else {
 133                if (lapb->mode & LAPB_DCE) {
 134                        if (skb->data[0] == LAPB_ADDR_B)
 135                                frame->cr = LAPB_COMMAND;
 136                        if (skb->data[0] == LAPB_ADDR_A)
 137                                frame->cr = LAPB_RESPONSE;
 138                } else {
 139                        if (skb->data[0] == LAPB_ADDR_A)
 140                                frame->cr = LAPB_COMMAND;
 141                        if (skb->data[0] == LAPB_ADDR_B)
 142                                frame->cr = LAPB_RESPONSE;
 143                }
 144        }
 145                
 146        skb_pull(skb, 1);
 147
 148        if (lapb->mode & LAPB_EXTENDED) {
 149                if ((skb->data[0] & LAPB_S) == 0) {
 150                        frame->type       = LAPB_I;                     /* I frame - carries NR/NS/PF */
 151                        frame->ns         = (skb->data[0] >> 1) & 0x7F;
 152                        frame->nr         = (skb->data[1] >> 1) & 0x7F;
 153                        frame->pf         = skb->data[1] & LAPB_EPF;
 154                        frame->control[0] = skb->data[0];
 155                        frame->control[1] = skb->data[1];
 156                        skb_pull(skb, 2);
 157                } else if ((skb->data[0] & LAPB_U) == 1) {      /* S frame - take out PF/NR */
 158                        frame->type       = skb->data[0] & 0x0F;
 159                        frame->nr         = (skb->data[1] >> 1) & 0x7F;
 160                        frame->pf         = skb->data[1] & LAPB_EPF;
 161                        frame->control[0] = skb->data[0];
 162                        frame->control[1] = skb->data[1];
 163                        skb_pull(skb, 2);
 164                } else if ((skb->data[0] & LAPB_U) == 3) {      /* U frame - take out PF */
 165                        frame->type       = skb->data[0] & ~LAPB_SPF;
 166                        frame->pf         = skb->data[0] & LAPB_SPF;
 167                        frame->control[0] = skb->data[0];
 168                        frame->control[1] = 0x00;
 169                        skb_pull(skb, 1);
 170                }
 171        } else {
 172                if ((skb->data[0] & LAPB_S) == 0) {
 173                        frame->type = LAPB_I;                   /* I frame - carries NR/NS/PF */
 174                        frame->ns   = (skb->data[0] >> 1) & 0x07;
 175                        frame->nr   = (skb->data[0] >> 5) & 0x07;
 176                        frame->pf   = skb->data[0] & LAPB_SPF;
 177                } else if ((skb->data[0] & LAPB_U) == 1) {      /* S frame - take out PF/NR */
 178                        frame->type = skb->data[0] & 0x0F;
 179                        frame->nr   = (skb->data[0] >> 5) & 0x07;
 180                        frame->pf   = skb->data[0] & LAPB_SPF;
 181                } else if ((skb->data[0] & LAPB_U) == 3) {      /* U frame - take out PF */
 182                        frame->type = skb->data[0] & ~LAPB_SPF;
 183                        frame->pf   = skb->data[0] & LAPB_SPF;
 184                }
 185
 186                frame->control[0] = skb->data[0];
 187
 188                skb_pull(skb, 1);
 189        }
 190}
 191
 192/* 
 193 *      This routine is called when the HDLC layer internally  generates a
 194 *      command or  response  for  the remote machine ( eg. RR, UA etc. ). 
 195 *      Only supervisory or unnumbered frames are processed, FRMRs are handled
 196 *      by lapb_transmit_frmr below.
 197 */
 198void lapb_send_control(lapb_cb *lapb, int frametype, int poll_bit, int type)
 199{
 200        struct sk_buff *skb;
 201        unsigned char  *dptr;
 202
 203        if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL)
 204                return;
 205
 206        skb_reserve(skb, LAPB_HEADER_LEN + 1);
 207
 208        if (lapb->mode & LAPB_EXTENDED) {
 209                if ((frametype & LAPB_U) == LAPB_U) {
 210                        dptr   = skb_put(skb, 1);
 211                        *dptr  = frametype;
 212                        *dptr |= (poll_bit) ? LAPB_SPF : 0;
 213                } else {
 214                        dptr     = skb_put(skb, 2);
 215                        dptr[0]  = frametype;
 216                        dptr[1]  = (lapb->vr << 1);
 217                        dptr[1] |= (poll_bit) ? LAPB_EPF : 0;
 218                }
 219        } else {
 220                dptr   = skb_put(skb, 1);
 221                *dptr  = frametype;
 222                *dptr |= (poll_bit) ? LAPB_SPF : 0;
 223                if ((frametype & LAPB_U) == LAPB_S)             /* S frames carry NR */
 224                        *dptr |= (lapb->vr << 5);
 225        }
 226
 227        lapb_transmit_buffer(lapb, skb, type);
 228}
 229
 230/* 
 231 *      This routine generates FRMRs based on information previously stored in
 232 *      the LAPB control block.
 233 */
 234void lapb_transmit_frmr(lapb_cb *lapb)
 235{
 236        struct sk_buff *skb;
 237        unsigned char  *dptr;
 238
 239        if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL)
 240                return;
 241
 242        skb_reserve(skb, LAPB_HEADER_LEN + 1);
 243
 244        if (lapb->mode & LAPB_EXTENDED) {
 245                dptr    = skb_put(skb, 6);
 246                *dptr++ = LAPB_FRMR;
 247                *dptr++ = lapb->frmr_data.control[0];
 248                *dptr++ = lapb->frmr_data.control[1];
 249                *dptr++ = (lapb->vs << 1) & 0xFE;
 250                *dptr   = (lapb->vr << 1) & 0xFE;
 251                if (lapb->frmr_data.cr == LAPB_RESPONSE)
 252                        *dptr |= 0x01;
 253                dptr++;
 254                *dptr++ = lapb->frmr_type;
 255
 256#if LAPB_DEBUG > 1
 257        printk(KERN_DEBUG "lapb: (%p) S%d TX FRMR %02X %02X %02X %02X %02X\n", lapb->token, lapb->state, skb->data[1], skb->data[2], skb->data[3], skb->data[4], skb->data[5]);
 258#endif
 259        } else {
 260                dptr    = skb_put(skb, 4);
 261                *dptr++ = LAPB_FRMR;
 262                *dptr++ = lapb->frmr_data.control[0];
 263                *dptr   = (lapb->vs << 1) & 0x0E;
 264                *dptr  |= (lapb->vr << 5) & 0xE0;
 265                if (lapb->frmr_data.cr == LAPB_RESPONSE)
 266                        *dptr |= 0x10;
 267                dptr++;
 268                *dptr++ = lapb->frmr_type;
 269
 270#if LAPB_DEBUG > 1
 271        printk(KERN_DEBUG "lapb: (%p) S%d TX FRMR %02X %02X %02X\n", lapb->token, lapb->state, skb->data[1], skb->data[2], skb->data[3]);
 272#endif
 273        }
 274
 275        lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE);
 276}
 277