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 *      LAPB 002        Jonathan Naylor New timer architecture.
  15 */
  16
  17#include <linux/errno.h>
  18#include <linux/types.h>
  19#include <linux/socket.h>
  20#include <linux/in.h>
  21#include <linux/kernel.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 <linux/slab.h>
  29#include <net/sock.h>
  30#include <asm/uaccess.h>
  31#include <asm/system.h>
  32#include <linux/fcntl.h>
  33#include <linux/mm.h>
  34#include <linux/interrupt.h>
  35#include <net/lapb.h>
  36
  37/*
  38 *  This procedure is passed a buffer descriptor for an iframe. It builds
  39 *  the rest of the control part of the frame and then writes it out.
  40 */
  41static void lapb_send_iframe(struct lapb_cb *lapb, struct sk_buff *skb, int poll_bit)
  42{
  43        unsigned char *frame;
  44
  45        if (!skb)
  46                return;
  47
  48        if (lapb->mode & LAPB_EXTENDED) {
  49                frame = skb_push(skb, 2);
  50
  51                frame[0] = LAPB_I;
  52                frame[0] |= lapb->vs << 1;
  53                frame[1] = poll_bit ? LAPB_EPF : 0;
  54                frame[1] |= lapb->vr << 1;
  55        } else {
  56                frame = skb_push(skb, 1);
  57
  58                *frame = LAPB_I;
  59                *frame |= poll_bit ? LAPB_SPF : 0;
  60                *frame |= lapb->vr << 5;
  61                *frame |= lapb->vs << 1;
  62        }
  63
  64#if LAPB_DEBUG > 1
  65        printk(KERN_DEBUG "lapb: (%p) S%d TX I(%d) S%d R%d\n",
  66               lapb->dev, lapb->state, poll_bit, lapb->vs, lapb->vr);
  67#endif
  68
  69        lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);
  70}
  71
  72void lapb_kick(struct lapb_cb *lapb)
  73{
  74        struct sk_buff *skb, *skbn;
  75        unsigned short modulus, start, end;
  76
  77        modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
  78        start = !skb_peek(&lapb->ack_queue) ? lapb->va : lapb->vs;
  79        end   = (lapb->va + lapb->window) % modulus;
  80
  81        if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&
  82            start != end && skb_peek(&lapb->write_queue)) {
  83                lapb->vs = start;
  84
  85                /*
  86                 * Dequeue the frame and copy it.
  87                 */
  88                skb = skb_dequeue(&lapb->write_queue);
  89
  90                do {
  91                        if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
  92                                skb_queue_head(&lapb->write_queue, skb);
  93                                break;
  94                        }
  95
  96                        if (skb->sk)
  97                                skb_set_owner_w(skbn, skb->sk);
  98
  99                        /*
 100                         * Transmit the frame copy.
 101                         */
 102                        lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);
 103
 104                        lapb->vs = (lapb->vs + 1) % modulus;
 105
 106                        /*
 107                         * Requeue the original data frame.
 108                         */
 109                        skb_queue_tail(&lapb->ack_queue, skb);
 110
 111                } while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);
 112
 113                lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 114
 115                if (!lapb_t1timer_running(lapb))
 116                        lapb_start_t1timer(lapb);
 117        }
 118}
 119
 120void lapb_transmit_buffer(struct lapb_cb *lapb, struct sk_buff *skb, int type)
 121{
 122        unsigned char *ptr;
 123
 124        ptr = skb_push(skb, 1);
 125
 126        if (lapb->mode & LAPB_MLP) {
 127                if (lapb->mode & LAPB_DCE) {
 128                        if (type == LAPB_COMMAND)
 129                                *ptr = LAPB_ADDR_C;
 130                        if (type == LAPB_RESPONSE)
 131                                *ptr = LAPB_ADDR_D;
 132                } else {
 133                        if (type == LAPB_COMMAND)
 134                                *ptr = LAPB_ADDR_D;
 135                        if (type == LAPB_RESPONSE)
 136                                *ptr = LAPB_ADDR_C;
 137                }
 138        } else {
 139                if (lapb->mode & LAPB_DCE) {
 140                        if (type == LAPB_COMMAND)
 141                                *ptr = LAPB_ADDR_A;
 142                        if (type == LAPB_RESPONSE)
 143                                *ptr = LAPB_ADDR_B;
 144                } else {
 145                        if (type == LAPB_COMMAND)
 146                                *ptr = LAPB_ADDR_B;
 147                        if (type == LAPB_RESPONSE)
 148                                *ptr = LAPB_ADDR_A;
 149                }
 150        }
 151
 152#if LAPB_DEBUG > 2
 153        printk(KERN_DEBUG "lapb: (%p) S%d TX %02X %02X %02X\n",
 154               lapb->dev, lapb->state,
 155               skb->data[0], skb->data[1], skb->data[2]);
 156#endif
 157
 158        if (!lapb_data_transmit(lapb, skb))
 159                kfree_skb(skb);
 160}
 161
 162void lapb_establish_data_link(struct lapb_cb *lapb)
 163{
 164        lapb->condition = 0x00;
 165        lapb->n2count   = 0;
 166
 167        if (lapb->mode & LAPB_EXTENDED) {
 168#if LAPB_DEBUG > 1
 169                printk(KERN_DEBUG "lapb: (%p) S%d TX SABME(1)\n",
 170                       lapb->dev, lapb->state);
 171#endif
 172                lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
 173        } else {
 174#if LAPB_DEBUG > 1
 175                printk(KERN_DEBUG "lapb: (%p) S%d TX SABM(1)\n",
 176                       lapb->dev, lapb->state);
 177#endif
 178                lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
 179        }
 180
 181        lapb_start_t1timer(lapb);
 182        lapb_stop_t2timer(lapb);
 183}
 184
 185void lapb_enquiry_response(struct lapb_cb *lapb)
 186{
 187#if LAPB_DEBUG > 1
 188        printk(KERN_DEBUG "lapb: (%p) S%d TX RR(1) R%d\n",
 189               lapb->dev, lapb->state, lapb->vr);
 190#endif
 191
 192        lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
 193
 194        lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 195}
 196
 197void lapb_timeout_response(struct lapb_cb *lapb)
 198{
 199#if LAPB_DEBUG > 1
 200        printk(KERN_DEBUG "lapb: (%p) S%d TX RR(0) R%d\n",
 201               lapb->dev, lapb->state, lapb->vr);
 202#endif
 203        lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
 204
 205        lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 206}
 207
 208void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr)
 209{
 210        if (lapb->vs == nr) {
 211                lapb_frames_acked(lapb, nr);
 212                lapb_stop_t1timer(lapb);
 213                lapb->n2count = 0;
 214        } else if (lapb->va != nr) {
 215                lapb_frames_acked(lapb, nr);
 216                lapb_start_t1timer(lapb);
 217        }
 218}
 219
 220void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf)
 221{
 222        if (type == LAPB_COMMAND && pf)
 223                lapb_enquiry_response(lapb);
 224}
 225