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                         if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
  86                                 skb_queue_head(&lapb->write_queue, skb);
  87                                 break;
  88                         }
  89
  90                         if (skb->sk)
  91                                 skb_set_owner_w(skbn, skb->sk);
  92
  93                         /*
  94                          * Transmit the frame copy.
  95                          */
  96                         lapb_send_iframe(lapb, skbn, LAPB_POLLOFF);
  97
  98                         lapb->vs = (lapb->vs + 1) % modulus;
  99
 100                         /*
 101                          * Requeue the original data frame.
 102                          */
 103                         skb_queue_tail(&lapb->ack_queue, skb);
 104
 105                 } while (lapb->vs != end && (skb = skb_dequeue(&lapb->write_queue)) != NULL);
 106
 107                 lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 108
 109                 if (!lapb_t1timer_running(lapb))
 110                         lapb_start_t1timer(lapb);
 111         }
 112 }
 113
 114 void lapb_transmit_buffer(struct lapb_cb *lapb, struct sk_buff *skb, int type)
 115 {
 116         unsigned char *ptr;
 117
 118         ptr = skb_push(skb, 1);
 119
 120         if (lapb->mode & LAPB_MLP) {
 121                 if (lapb->mode & LAPB_DCE) {
 122                         if (type == LAPB_COMMAND)
 123                                 *ptr = LAPB_ADDR_C;
 124                         if (type == LAPB_RESPONSE)
 125                                 *ptr = LAPB_ADDR_D;
 126                 } else {
 127                         if (type == LAPB_COMMAND)
 128                                 *ptr = LAPB_ADDR_D;
 129                         if (type == LAPB_RESPONSE)
 130                                 *ptr = LAPB_ADDR_C;
 131                 }
 132         } else {
 133                 if (lapb->mode & LAPB_DCE) {
 134                         if (type == LAPB_COMMAND)
 135                                 *ptr = LAPB_ADDR_A;
 136                         if (type == LAPB_RESPONSE)
 137                                 *ptr = LAPB_ADDR_B;
 138                 } else {
 139                         if (type == LAPB_COMMAND)
 140                                 *ptr = LAPB_ADDR_B;
 141                         if (type == LAPB_RESPONSE)
 142                                 *ptr = LAPB_ADDR_A;
 143                 }
 144         }
 145
 146         lapb_dbg(2, "(%p) S%d TX %3ph\n", lapb->dev, lapb->state, skb->data);
 147
 148         if (!lapb_data_transmit(lapb, skb))
 149                 kfree_skb(skb);
 150 }
 151
 152 void lapb_establish_data_link(struct lapb_cb *lapb)
 153 {
 154         lapb->condition = 0x00;
 155         lapb->n2count   = 0;
 156
 157         if (lapb->mode & LAPB_EXTENDED) {
 158                 lapb_dbg(1, "(%p) S%d TX SABME(1)\n", lapb->dev, lapb->state);
 159                 lapb_send_control(lapb, LAPB_SABME, LAPB_POLLON, LAPB_COMMAND);
 160         } else {
 161                 lapb_dbg(1, "(%p) S%d TX SABM(1)\n", lapb->dev, lapb->state);
 162                 lapb_send_control(lapb, LAPB_SABM, LAPB_POLLON, LAPB_COMMAND);
 163         }
 164
 165         lapb_start_t1timer(lapb);
 166         lapb_stop_t2timer(lapb);
 167 }
 168
 169 void lapb_enquiry_response(struct lapb_cb *lapb)
 170 {
 171         lapb_dbg(1, "(%p) S%d TX RR(1) R%d\n",
 172                  lapb->dev, lapb->state, lapb->vr);
 173
 174         lapb_send_control(lapb, LAPB_RR, LAPB_POLLON, LAPB_RESPONSE);
 175
 176         lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 177 }
 178
 179 void lapb_timeout_response(struct lapb_cb *lapb)
 180 {
 181         lapb_dbg(1, "(%p) S%d TX RR(0) R%d\n",
 182                  lapb->dev, lapb->state, lapb->vr);
 183         lapb_send_control(lapb, LAPB_RR, LAPB_POLLOFF, LAPB_RESPONSE);
 184
 185         lapb->condition &= ~LAPB_ACK_PENDING_CONDITION;
 186 }
 187
 188 void lapb_check_iframes_acked(struct lapb_cb *lapb, unsigned short nr)
 189 {
 190         if (lapb->vs == nr) {
 191                 lapb_frames_acked(lapb, nr);
 192                 lapb_stop_t1timer(lapb);
 193                 lapb->n2count = 0;
 194         } else if (lapb->va != nr) {
 195                 lapb_frames_acked(lapb, nr);
 196                 lapb_start_t1timer(lapb);
 197         }
 198 }
 199
 200 void lapb_check_need_response(struct lapb_cb *lapb, int type, int pf)
 201 {
 202         if (type == LAPB_COMMAND && pf)
 203                 lapb_enquiry_response(lapb);
 204 }