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