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 <linux/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                         skbn = skb_copy(skb, GFP_ATOMIC);
  91                         if (!skbn) {
  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
 120 void 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         lapb_dbg(2, "(%p) S%d TX %3ph\n", lapb->dev, lapb->state, skb->data);
 153
 154         if (!lapb_data_transmit(lapb, skb))
 155                 kfree_skb(skb);
 156 }
 157
 158 void lapb_establish_data_link(struct lapb_cb *lapb)
 159 {
 160         lapb->condition = 0x00;
 161         lapb->n2count   = 0;
 162
 163         if (lapb->mode & LAPB_EXTENDED) {
 164                 lapb_dbg(1, "(%p) S%d TX SABME(1)\n", lapb->dev, lapb->state);
 165                 lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
 166         } else {
 167                 lapb_dbg(1, "(%p) S%d TX SABM(1)\n", lapb->dev, lapb->state);
 168                 lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
 169         }
 170
 171         lapb_start_t1timer(lapb);
 172         lapb_stop_t2timer(lapb);
 173 }
 174
 175 void lapb_enquiry_response(struct lapb_cb *lapb)
 176 {
 177         lapb_dbg(1, "(%p) S%d TX RR(1) R%d\n",
 178                  lapb->dev, lapb->state, lapb->vr);
 179
 180         lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
 181
 182         lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 183 }
 184
 185 void lapb_timeout_response(struct lapb_cb *lapb)
 186 {
 187         lapb_dbg(1, "(%p) S%d TX RR(0) R%d\n",
 188                  lapb->dev, lapb->state, lapb->vr);
 189         lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
 190
 191         lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 192 }
 193
 194 void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr)
 195 {
 196         if (lapb->vs == nr) {
 197                 lapb_frames_acked(lapb, nr);
 198                 lapb_stop_t1timer(lapb);
 199                 lapb->n2count = 0;
 200         } else if (lapb->va != nr) {
 201                 lapb_frames_acked(lapb, nr);
 202                 lapb_start_t1timer(lapb);
 203         }
 204 }
 205
 206 void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf)
 207 {
 208         if (type == LAPB_COMMAND && pf)
 209                 lapb_enquiry_response(lapb);
 210 }