net/lapb/lapb_out.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      LAPB release 002
   4  *
   5  *      This code REQUIRES 2.1.15 or higher/ NET3.038
   6  *
   7  *      History
   8  *      LAPB 001        Jonathan Naylor Started Coding
   9  *      LAPB 002        Jonathan Naylor New timer architecture.
  10  */
  11
  12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  13
  14 #include <linux/errno.h>
  15 #include <linux/types.h>
  16 #include <linux/socket.h>
  17 #include <linux/in.h>
  18 #include <linux/kernel.h>
  19 #include <linux/timer.h>
  20 #include <linux/string.h>
  21 #include <linux/sockios.h>
  22 #include <linux/net.h>
  23 #include <linux/inet.h>
  24 #include <linux/skbuff.h>
  25 #include <linux/slab.h>
  26 #include <net/sock.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/fcntl.h>
  29 #include <linux/mm.h>
  30 #include <linux/interrupt.h>
  31 #include <net/lapb.h>
  32
  33 /*
  34  *  This procedure is passed a buffer descriptor for an iframe. It builds
  35  *  the rest of the control part of the frame and then writes it out.
  36  */
  37 static void lapb_send_iframe(struct lapb_cb *lapb, struct sk_buff *skb, int poll_bit)
  38 {
  39         unsigned char *frame;
  40
  41         if (!skb)
  42                 return;
  43
  44         if (lapb->mode & LAPB_EXTENDED) {
  45                 frame = skb_push(skb, 2);
  46
  47                 frame[0] = LAPB_I;
  48                 frame[0] |= lapb->vs << 1;
  49                 frame[1] = poll_bit ? LAPB_EPF : 0;
  50                 frame[1] |= lapb->vr << 1;
  51         } else {
  52                 frame = skb_push(skb, 1);
  53
  54                 *frame = LAPB_I;
  55                 *frame |= poll_bit ? LAPB_SPF : 0;
  56                 *frame |= lapb->vr << 5;
  57                 *frame |= lapb->vs << 1;
  58         }
  59
  60         lapb_dbg(1, "(%p) S%d TX I(%d) S%d R%d\n",
  61                  lapb->dev, lapb->state, poll_bit, lapb->vs, lapb->vr);
  62
  63         lapb_transmit_buffer(lapb, skb, LAPB_COMMAND);
  64 }
  65
  66 void lapb_kick(struct lapb_cb *lapb)
  67 {
  68         struct sk_buff *skb, *skbn;
  69         unsigned short modulus, start, end;
  70
  71         modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
  72         start = !skb_peek(&lapb->ack_queue) ? lapb->va : lapb->vs;
  73         end   = (lapb->va + lapb->window) % modulus;
  74
  75         if (!(lapb->condition & LAPB_PEER_RX_BUSY_CONDITION) &&
  76             start != end && skb_peek(&lapb->write_queue)) {
  77                 lapb->vs = start;
  78
  79                 /*
  80                  * Dequeue the frame and copy it.
  81                  */
  82                 skb = skb_dequeue(&lapb->write_queue);
  83
  84                 do {
  85                         skbn = skb_copy(skb, GFP_ATOMIC);
  86                         if (!skbn) {
  87                                 skb_queue_head(&lapb->write_queue, skb);
  88                                 break;
  89                         }
  90
  91                         if (skb->sk)
  92                                 skb_set_owner_w(skbn, skb->sk);
  93
  94                         /*
  95                          * Transmit the frame copy.
  96                          */
  97                         lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);
  98
  99                         lapb->vs = (lapb->vs + 1) % modulus;
 100
 101                         /*
 102                          * Requeue the original data frame.
 103                          */
 104                         skb_queue_tail(&lapb->ack_queue, skb);
 105
 106                 } while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);
 107
 108                 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 109
 110                 if (!lapb_t1timer_running(lapb))
 111                         lapb_start_t1timer(lapb);
 112         }
 113 }
 114
 115 void lapb_transmit_buffer(struct lapb_cb *lapb, struct sk_buff *skb, int type)
 116 {
 117         unsigned char *ptr;
 118
 119         ptr = skb_push(skb, 1);
 120
 121         if (lapb->mode & LAPB_MLP) {
 122                 if (lapb->mode & LAPB_DCE) {
 123                         if (type == LAPB_COMMAND)
 124                                 *ptr = LAPB_ADDR_C;
 125                         if (type == LAPB_RESPONSE)
 126                                 *ptr = LAPB_ADDR_D;
 127                 } else {
 128                         if (type == LAPB_COMMAND)
 129                                 *ptr = LAPB_ADDR_D;
 130                         if (type == LAPB_RESPONSE)
 131                                 *ptr = LAPB_ADDR_C;
 132                 }
 133         } else {
 134                 if (lapb->mode & LAPB_DCE) {
 135                         if (type == LAPB_COMMAND)
 136                                 *ptr = LAPB_ADDR_A;
 137                         if (type == LAPB_RESPONSE)
 138                                 *ptr = LAPB_ADDR_B;
 139                 } else {
 140                         if (type == LAPB_COMMAND)
 141                                 *ptr = LAPB_ADDR_B;
 142                         if (type == LAPB_RESPONSE)
 143                                 *ptr = LAPB_ADDR_A;
 144                 }
 145         }
 146
 147         lapb_dbg(2, "(%p) S%d TX %3ph\n", lapb->dev, lapb->state, skb->data);
 148
 149         if (!lapb_data_transmit(lapb, skb))
 150                 kfree_skb(skb);
 151 }
 152
 153 void lapb_establish_data_link(struct lapb_cb *lapb)
 154 {
 155         lapb->condition = 0x00;
 156         lapb->n2count   = 0;
 157
 158         if (lapb->mode & LAPB_EXTENDED) {
 159                 lapb_dbg(1, "(%p) S%d TX SABME(1)\n", lapb->dev, lapb->state);
 160                 lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
 161         } else {
 162                 lapb_dbg(1, "(%p) S%d TX SABM(1)\n", lapb->dev, lapb->state);
 163                 lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
 164         }
 165
 166         lapb_start_t1timer(lapb);
 167         lapb_stop_t2timer(lapb);
 168 }
 169
 170 void lapb_enquiry_response(struct lapb_cb *lapb)
 171 {
 172         lapb_dbg(1, "(%p) S%d TX RR(1) R%d\n",
 173                  lapb->dev, lapb->state, lapb->vr);
 174
 175         lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
 176
 177         lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 178 }
 179
 180 void lapb_timeout_response(struct lapb_cb *lapb)
 181 {
 182         lapb_dbg(1, "(%p) S%d TX RR(0) R%d\n",
 183                  lapb->dev, lapb->state, lapb->vr);
 184         lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
 185
 186         lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 187 }
 188
 189 void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr)
 190 {
 191         if (lapb->vs == nr) {
 192                 lapb_frames_acked(lapb, nr);
 193                 lapb_stop_t1timer(lapb);
 194                 lapb->n2count = 0;
 195         } else if (lapb->va != nr) {
 196                 lapb_frames_acked(lapb, nr);
 197                 lapb_start_t1timer(lapb);
 198         }
 199 }
 200
 201 void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf)
 202 {
 203         if (type == LAPB_COMMAND && pf)
 204                 lapb_enquiry_response(lapb);
 205 }