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 #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  */
  42 static 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
  71 void 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
 119 void 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
 159 void 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
 176 void 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
 186 void 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
 195 void 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
 207 void 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 }