net/lapb/lapb_subr.c

   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/config.h>
  17 #if defined(CONFIG_LAPB) || defined(CONFIG_LAPB_MODULE)
  18 #include <linux/errno.h>
  19 #include <linux/types.h>
  20 #include <linux/socket.h>
  21 #include <linux/in.h>
  22 #include <linux/kernel.h>
  23 #include <linux/sched.h>
  24 #include <linux/timer.h>
  25 #include <linux/string.h>
  26 #include <linux/sockios.h>
  27 #include <linux/net.h>
  28 #include <linux/inet.h>
  29 #include <linux/skbuff.h>
  30 #include <net/sock.h>
  31 #include <asm/uaccess.h>
  32 #include <asm/system.h>
  33 #include <linux/fcntl.h>
  34 #include <linux/mm.h>
  35 #include <linux/interrupt.h>
  36 #include <net/lapb.h>
  37
  38 /*
  39  *      This routine purges all the queues of frames.
  40  */
  41 void lapb_clear_queues(lapb_cb *lapb)
  42 {
  43         struct sk_buff *skb;
  44
  45         while ((skb = skb_dequeue(&lapb->write_queue)) != NULL)
  46                 kfree_skb(skb);
  47
  48         while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL)
  49                 kfree_skb(skb);
  50 }
  51
  52 /*
  53  * This routine purges the input queue of those frames that have been
  54  * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
  55  * SDL diagram.
  56  */
  57 void lapb_frames_acked(lapb_cb *lapb, unsigned short nr)
  58 {
  59         struct sk_buff *skb;
  60         int modulus;
  61
  62         modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
  63
  64         /*
  65          * Remove all the ack-ed frames from the ack queue.
  66          */
  67         if (lapb->va != nr) {
  68                 while (skb_peek(&lapb->ack_queue) != NULL && lapb->va != nr) {
  69                         skb = skb_dequeue(&lapb->ack_queue);
  70                         kfree_skb(skb);
  71                         lapb->va = (lapb->va + 1) % modulus;
  72                 }
  73         }
  74 }
  75
  76 void lapb_requeue_frames(lapb_cb *lapb)
  77 {
  78         struct sk_buff *skb, *skb_prev = NULL;
  79
  80         /*
  81          * Requeue all the un-ack-ed frames on the output queue to be picked
  82          * up by lapb_kick called from the timer. This arrangement handles the
  83          * possibility of an empty output queue.
  84          */
  85         while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) {
  86                 if (skb_prev == NULL)
  87                         skb_queue_head(&lapb->write_queue, skb);
  88                 else
  89                         skb_append(skb_prev, skb);
  90                 skb_prev = skb;
  91         }
  92 }
  93
  94 /*
  95  *      Validate that the value of nr is between va and vs. Return true or
  96  *      false for testing.
  97  */
  98 int lapb_validate_nr(lapb_cb *lapb, unsigned short nr)
  99 {
 100         unsigned short vc = lapb->va;
 101         int modulus;
 102
 103         modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
 104
 105         while (vc != lapb->vs) {
 106                 if (nr == vc) return 1;
 107                 vc = (vc + 1) % modulus;
 108         }
 109
 110         if (nr == lapb->vs) return 1;
 111
 112         return 0;
 113 }
 114
 115 /*
 116  *      This routine is the centralised routine for parsing the control
 117  *      information for the different frame formats.
 118  */
 119 void lapb_decode(lapb_cb *lapb, struct sk_buff *skb, struct lapb_frame *frame)
 120 {
 121         frame->type = LAPB_ILLEGAL;
 122
 123 #if LAPB_DEBUG > 2
 124         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]);
 125 #endif
 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) == 0) {
 157                         frame->type       = LAPB_I;                     /* I frame - carries NR/NS/PF */
 158                         frame->ns         = (skb->data[0] >> 1) & 0x7F;
 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) == 1) {      /* S frame - take out PF/NR */
 165                         frame->type       = skb->data[0] & 0x0F;
 166                         frame->nr         = (skb->data[1] >> 1) & 0x7F;
 167                         frame->pf         = skb->data[1] & LAPB_EPF;
 168                         frame->control[0] = skb->data[0];
 169                         frame->control[1] = skb->data[1];
 170                         skb_pull(skb, 2);
 171                 } else if ((skb->data[0] & LAPB_U) == 3) {      /* U frame - take out PF */
 172                         frame->type       = skb->data[0] & ~LAPB_SPF;
 173                         frame->pf         = skb->data[0] & LAPB_SPF;
 174                         frame->control[0] = skb->data[0];
 175                         frame->control[1] = 0x00;
 176                         skb_pull(skb, 1);
 177                 }
 178         } else {
 179                 if ((skb->data[0] & LAPB_S) == 0) {
 180                         frame->type = LAPB_I;                   /* I frame - carries NR/NS/PF */
 181                         frame->ns   = (skb->data[0] >> 1) & 0x07;
 182                         frame->nr   = (skb->data[0] >> 5) & 0x07;
 183                         frame->pf   = skb->data[0] & LAPB_SPF;
 184                 } else if ((skb->data[0] & LAPB_U) == 1) {      /* S frame - take out PF/NR */
 185                         frame->type = skb->data[0] & 0x0F;
 186                         frame->nr   = (skb->data[0] >> 5) & 0x07;
 187                         frame->pf   = skb->data[0] & LAPB_SPF;
 188                 } else if ((skb->data[0] & LAPB_U) == 3) {      /* U frame - take out PF */
 189                         frame->type = skb->data[0] & ~LAPB_SPF;
 190                         frame->pf   = skb->data[0] & LAPB_SPF;
 191                 }
 192
 193                 frame->control[0] = skb->data[0];
 194
 195                 skb_pull(skb, 1);
 196         }
 197 }
 198
 199 /*
 200  *      This routine is called when the HDLC layer internally  generates a
 201  *      command or  response  for  the remote machine ( eg. RR, UA etc. ).
 202  *      Only supervisory or unnumbered frames are processed, FRMRs are handled
 203  *      by lapb_transmit_frmr below.
 204  */
 205 void lapb_send_control(lapb_cb *lapb, int frametype, int poll_bit, int type)
 206 {
 207         struct sk_buff *skb;
 208         unsigned char  *dptr;
 209
 210         if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL)
 211                 return;
 212
 213         skb_reserve(skb, LAPB_HEADER_LEN + 1);
 214
 215         if (lapb->mode & LAPB_EXTENDED) {
 216                 if ((frametype & LAPB_U) == LAPB_U) {
 217                         dptr   = skb_put(skb, 1);
 218                         *dptr  = frametype;
 219                         *dptr |= (poll_bit) ? LAPB_SPF : 0;
 220                 } else {
 221                         dptr     = skb_put(skb, 2);
 222                         dptr[0]  = frametype;
 223                         dptr[1]  = (lapb->vr << 1);
 224                         dptr[1] |= (poll_bit) ? LAPB_EPF : 0;
 225                 }
 226         } else {
 227                 dptr   = skb_put(skb, 1);
 228                 *dptr  = frametype;
 229                 *dptr |= (poll_bit) ? LAPB_SPF : 0;
 230                 if ((frametype & LAPB_U) == LAPB_S)             /* S frames carry NR */
 231                         *dptr |= (lapb->vr << 5);
 232         }
 233
 234         lapb_transmit_buffer(lapb, skb, type);
 235 }
 236
 237 /*
 238  *      This routine generates FRMRs based on information previously stored in
 239  *      the LAPB control block.
 240  */
 241 void lapb_transmit_frmr(lapb_cb *lapb)
 242 {
 243         struct sk_buff *skb;
 244         unsigned char  *dptr;
 245
 246         if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL)
 247                 return;
 248
 249         skb_reserve(skb, LAPB_HEADER_LEN + 1);
 250
 251         if (lapb->mode & LAPB_EXTENDED) {
 252                 dptr    = skb_put(skb, 6);
 253                 *dptr++ = LAPB_FRMR;
 254                 *dptr++ = lapb->frmr_data.control[0];
 255                 *dptr++ = lapb->frmr_data.control[1];
 256                 *dptr++ = (lapb->vs << 1) & 0xFE;
 257                 *dptr   = (lapb->vr << 1) & 0xFE;
 258                 if (lapb->frmr_data.cr == LAPB_RESPONSE)
 259                         *dptr |= 0x01;
 260                 dptr++;
 261                 *dptr++ = lapb->frmr_type;
 262
 263 #if LAPB_DEBUG > 1
 264         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]);
 265 #endif
 266         } else {
 267                 dptr    = skb_put(skb, 4);
 268                 *dptr++ = LAPB_FRMR;
 269                 *dptr++ = lapb->frmr_data.control[0];
 270                 *dptr   = (lapb->vs << 1) & 0x0E;
 271                 *dptr  |= (lapb->vr << 5) & 0xE0;
 272                 if (lapb->frmr_data.cr == LAPB_RESPONSE)
 273                         *dptr |= 0x10;
 274                 dptr++;
 275                 *dptr++ = lapb->frmr_type;
 276
 277 #if LAPB_DEBUG > 1
 278         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]);
 279 #endif
 280         }
 281
 282         lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE);
 283 }
 284
 285 #endif