net/lapb/lapb_out.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  *      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/sched.h>
  23 #include <linux/timer.h>
  24 #include <linux/string.h>
  25 #include <linux/sockios.h>
  26 #include <linux/net.h>
  27 #include <linux/inet.h>
  28 #include <linux/skbuff.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  */
  41 static void lapb_send_iframe(lapb_cb *lapb, struct sk_buff *skb, int poll_bit)
  42 {
  43         unsigned char *frame;
  44
  45         if (skb == NULL)
  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", lapb->token, lapb->state, poll_bit, lapb->vs, lapb->vr);
  66 #endif
  67
  68         lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);
  69 }
  70
  71 void lapb_kick(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
  78         start = (skb_peek(&lapb->ack_queue) == NULL) ? lapb->va : lapb->vs;
  79         end   = (lapb->va + lapb->window) % modulus;
  80
  81         if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&
  82             start != end                                &&
  83             skb_peek(&lapb->write_queue) != NULL) {
  84
  85                 lapb->vs = start;
  86
  87                 /*
  88                  * Dequeue the frame and copy it.
  89                  */
  90                 skb  = skb_dequeue(&lapb->write_queue);
  91
  92                 do {
  93                         if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
  94                                 skb_queue_head(&lapb->write_queue, skb);
  95                                 break;
  96                         }
  97
  98                         if (skb->sk != NULL)
  99                                 skb_set_owner_w(skbn, skb->sk);
 100
 101                         /*
 102                          * Transmit the frame copy.
 103                          */
 104                         lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);
 105
 106                         lapb->vs = (lapb->vs + 1) % modulus;
 107
 108                         /*
 109                          * Requeue the original data frame.
 110                          */
 111                         skb_queue_tail(&lapb->ack_queue, skb);
 112
 113                 } while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);
 114
 115                 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 116
 117                 if (!lapb_t1timer_running(lapb))
 118                         lapb_start_t1timer(lapb);
 119         }
 120 }
 121
 122 void lapb_transmit_buffer(lapb_cb *lapb, struct sk_buff *skb, int type)
 123 {
 124         unsigned char *ptr;
 125
 126         ptr = skb_push(skb, 1);
 127
 128         if (lapb->mode & LAPB_MLP) {
 129                 if (lapb->mode & LAPB_DCE) {
 130                         if (type == LAPB_COMMAND)
 131                                 *ptr = LAPB_ADDR_C;
 132                         if (type == LAPB_RESPONSE)
 133                                 *ptr = LAPB_ADDR_D;
 134                 } else {
 135                         if (type == LAPB_COMMAND)
 136                                 *ptr = LAPB_ADDR_D;
 137                         if (type == LAPB_RESPONSE)
 138                                 *ptr = LAPB_ADDR_C;
 139                 }
 140         } else {
 141                 if (lapb->mode & LAPB_DCE) {
 142                         if (type == LAPB_COMMAND)
 143                                 *ptr = LAPB_ADDR_A;
 144                         if (type == LAPB_RESPONSE)
 145                                 *ptr = LAPB_ADDR_B;
 146                 } else {
 147                         if (type == LAPB_COMMAND)
 148                                 *ptr = LAPB_ADDR_B;
 149                         if (type == LAPB_RESPONSE)
 150                                 *ptr = LAPB_ADDR_A;
 151                 }
 152         }
 153
 154 #if LAPB_DEBUG > 2
 155         printk(KERN_DEBUG "lapb: (%p) S%d TX %02X %02X %02X\n", lapb->token, lapb->state, 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
 162 void lapb_establish_data_link(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", lapb->token, lapb->state);
 170 #endif
 171                 lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
 172         } else {
 173 #if LAPB_DEBUG > 1
 174                 printk(KERN_DEBUG "lapb: (%p) S%d TX SABM(1)\n", lapb->token, lapb->state);
 175 #endif
 176                 lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
 177         }
 178
 179         lapb_start_t1timer(lapb);
 180         lapb_stop_t2timer(lapb);
 181 }
 182
 183 void lapb_enquiry_response(lapb_cb *lapb)
 184 {
 185 #if LAPB_DEBUG > 1
 186         printk(KERN_DEBUG "lapb: (%p) S%d TX RR(1) R%d\n", lapb->token, lapb->state, lapb->vr);
 187 #endif
 188
 189         lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
 190
 191         lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 192 }
 193
 194 void lapb_timeout_response(lapb_cb *lapb)
 195 {
 196 #if LAPB_DEBUG > 1
 197         printk(KERN_DEBUG "lapb: (%p) S%d TX RR(0) R%d\n", lapb->token, lapb->state, lapb->vr);
 198 #endif
 199
 200         lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
 201
 202         lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 203 }
 204
 205 void lapb_check_iframes_acked(lapb_cb *lapb, unsigned short nr)
 206 {
 207         if (lapb->vs == nr) {
 208                 lapb_frames_acked(lapb, nr);
 209                 lapb_stop_t1timer(lapb);
 210                 lapb->n2count = 0;
 211         } else {
 212                 if (lapb->va != nr) {
 213                         lapb_frames_acked(lapb, nr);
 214                         lapb_start_t1timer(lapb);
 215                 }
 216         }
 217 }
 218
 219 void lapb_check_need_response(lapb_cb *lapb, int type, int pf)
 220 {
 221         if (type == LAPB_COMMAND && pf)
 222                 lapb_enquiry_response(lapb);
 223 }