linux/net/ax25/ax25_std_timer.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *
   4 * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
   5 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   6 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
   7 * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
   8 */
   9#include <linux/errno.h>
  10#include <linux/types.h>
  11#include <linux/socket.h>
  12#include <linux/in.h>
  13#include <linux/kernel.h>
  14#include <linux/timer.h>
  15#include <linux/string.h>
  16#include <linux/sockios.h>
  17#include <linux/net.h>
  18#include <net/ax25.h>
  19#include <linux/inet.h>
  20#include <linux/netdevice.h>
  21#include <linux/skbuff.h>
  22#include <net/sock.h>
  23#include <net/tcp_states.h>
  24#include <linux/uaccess.h>
  25#include <linux/fcntl.h>
  26#include <linux/mm.h>
  27#include <linux/interrupt.h>
  28
  29void ax25_std_heartbeat_expiry(ax25_cb *ax25)
  30{
  31        struct sock *sk = ax25->sk;
  32
  33        if (sk)
  34                bh_lock_sock(sk);
  35
  36        switch (ax25->state) {
  37        case AX25_STATE_0:
  38        case AX25_STATE_2:
  39                /* Magic here: If we listen() and a new link dies before it
  40                   is accepted() it isn't 'dead' so doesn't get removed. */
  41                if (!sk || sock_flag(sk, SOCK_DESTROY) ||
  42                    (sk->sk_state == TCP_LISTEN &&
  43                     sock_flag(sk, SOCK_DEAD))) {
  44                        if (sk) {
  45                                sock_hold(sk);
  46                                ax25_destroy_socket(ax25);
  47                                bh_unlock_sock(sk);
  48                                /* Ungrab socket and destroy it */
  49                                sock_put(sk);
  50                        } else
  51                                ax25_destroy_socket(ax25);
  52                        return;
  53                }
  54                break;
  55
  56        case AX25_STATE_3:
  57        case AX25_STATE_4:
  58                /*
  59                 * Check the state of the receive buffer.
  60                 */
  61                if (sk != NULL) {
  62                        if (atomic_read(&sk->sk_rmem_alloc) <
  63                            (sk->sk_rcvbuf >> 1) &&
  64                            (ax25->condition & AX25_COND_OWN_RX_BUSY)) {
  65                                ax25->condition &= ~AX25_COND_OWN_RX_BUSY;
  66                                ax25->condition &= ~AX25_COND_ACK_PENDING;
  67                                ax25_send_control(ax25, AX25_RR, AX25_POLLOFF, AX25_RESPONSE);
  68                                break;
  69                        }
  70                }
  71        }
  72
  73        if (sk)
  74                bh_unlock_sock(sk);
  75
  76        ax25_start_heartbeat(ax25);
  77}
  78
  79void ax25_std_t2timer_expiry(ax25_cb *ax25)
  80{
  81        if (ax25->condition & AX25_COND_ACK_PENDING) {
  82                ax25->condition &= ~AX25_COND_ACK_PENDING;
  83                ax25_std_timeout_response(ax25);
  84        }
  85}
  86
  87void ax25_std_t3timer_expiry(ax25_cb *ax25)
  88{
  89        ax25->n2count = 0;
  90        ax25_std_transmit_enquiry(ax25);
  91        ax25->state   = AX25_STATE_4;
  92}
  93
  94void ax25_std_idletimer_expiry(ax25_cb *ax25)
  95{
  96        ax25_clear_queues(ax25);
  97
  98        ax25->n2count = 0;
  99        ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
 100        ax25->state   = AX25_STATE_2;
 101
 102        ax25_calculate_t1(ax25);
 103        ax25_start_t1timer(ax25);
 104        ax25_stop_t2timer(ax25);
 105        ax25_stop_t3timer(ax25);
 106
 107        if (ax25->sk != NULL) {
 108                bh_lock_sock(ax25->sk);
 109                ax25->sk->sk_state     = TCP_CLOSE;
 110                ax25->sk->sk_err       = 0;
 111                ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
 112                if (!sock_flag(ax25->sk, SOCK_DEAD)) {
 113                        ax25->sk->sk_state_change(ax25->sk);
 114                        sock_set_flag(ax25->sk, SOCK_DEAD);
 115                }
 116                bh_unlock_sock(ax25->sk);
 117        }
 118}
 119
 120void ax25_std_t1timer_expiry(ax25_cb *ax25)
 121{
 122        switch (ax25->state) {
 123        case AX25_STATE_1:
 124                if (ax25->n2count == ax25->n2) {
 125                        if (ax25->modulus == AX25_MODULUS) {
 126                                ax25_disconnect(ax25, ETIMEDOUT);
 127                                return;
 128                        } else {
 129                                ax25->modulus = AX25_MODULUS;
 130                                ax25->window  = ax25->ax25_dev->values[AX25_VALUES_WINDOW];
 131                                ax25->n2count = 0;
 132                                ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
 133                        }
 134                } else {
 135                        ax25->n2count++;
 136                        if (ax25->modulus == AX25_MODULUS)
 137                                ax25_send_control(ax25, AX25_SABM, AX25_POLLON, AX25_COMMAND);
 138                        else
 139                                ax25_send_control(ax25, AX25_SABME, AX25_POLLON, AX25_COMMAND);
 140                }
 141                break;
 142
 143        case AX25_STATE_2:
 144                if (ax25->n2count == ax25->n2) {
 145                        ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
 146                        if (!sock_flag(ax25->sk, SOCK_DESTROY))
 147                                ax25_disconnect(ax25, ETIMEDOUT);
 148                        return;
 149                } else {
 150                        ax25->n2count++;
 151                        ax25_send_control(ax25, AX25_DISC, AX25_POLLON, AX25_COMMAND);
 152                }
 153                break;
 154
 155        case AX25_STATE_3:
 156                ax25->n2count = 1;
 157                ax25_std_transmit_enquiry(ax25);
 158                ax25->state   = AX25_STATE_4;
 159                break;
 160
 161        case AX25_STATE_4:
 162                if (ax25->n2count == ax25->n2) {
 163                        ax25_send_control(ax25, AX25_DM, AX25_POLLON, AX25_RESPONSE);
 164                        ax25_disconnect(ax25, ETIMEDOUT);
 165                        return;
 166                } else {
 167                        ax25->n2count++;
 168                        ax25_std_transmit_enquiry(ax25);
 169                }
 170                break;
 171        }
 172
 173        ax25_calculate_t1(ax25);
 174        ax25_start_t1timer(ax25);
 175}
 176