// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 * Copyright (C) 2002 Ralf Baechle DO1GRB (ralf@gnu.org)
 */
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <linux/uaccess.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <net/netrom.h>

static void nr_heartbeat_expiry(struct timer_list *);
static void nr_t1timer_expiry(struct timer_list *);
static void nr_t2timer_expiry(struct timer_list *);
static void nr_t4timer_expiry(struct timer_list *);
static void nr_idletimer_expiry(struct timer_list *);

void nr_init_timers(struct sock *sk)
{
        struct nr_sock *nr = nr_sk(sk);

        timer_setup(&nr->t1timer, nr_t1timer_expiry, 0);
        timer_setup(&nr->t2timer, nr_t2timer_expiry, 0);
        timer_setup(&nr->t4timer, nr_t4timer_expiry, 0);
        timer_setup(&nr->idletimer, nr_idletimer_expiry, 0);

        /* initialized by sock_init_data */
        sk->sk_timer.function = nr_heartbeat_expiry;
}

void nr_start_t1timer(struct sock *sk)
{
        struct nr_sock *nr = nr_sk(sk);

        sk_reset_timer(sk, &nr->t1timer, jiffies + nr->t1);
}

void nr_start_t2timer(struct sock *sk)
{
        struct nr_sock *nr = nr_sk(sk);

        sk_reset_timer(sk, &nr->t2timer, jiffies + nr->t2);
}

void nr_start_t4timer(struct sock *sk)
{
        struct nr_sock *nr = nr_sk(sk);

        sk_reset_timer(sk, &nr->t4timer, jiffies + nr->t4);
}

void nr_start_idletimer(struct sock *sk)
{
        struct nr_sock *nr = nr_sk(sk);

        if (nr->idle > 0)
                sk_reset_timer(sk, &nr->idletimer, jiffies + nr->idle);
}

void nr_start_heartbeat(struct sock *sk)
{
        sk_reset_timer(sk, &sk->sk_timer, jiffies + 5 * HZ);
}

void nr_stop_t1timer(struct sock *sk)
{
        sk_stop_timer(sk, &nr_sk(sk)->t1timer);
}

void nr_stop_t2timer(struct sock *sk)
{
        sk_stop_timer(sk, &nr_sk(sk)->t2timer);
}

void nr_stop_t4timer(struct sock *sk)
{
        sk_stop_timer(sk, &nr_sk(sk)->t4timer);
}

void nr_stop_idletimer(struct sock *sk)
{
        sk_stop_timer(sk, &nr_sk(sk)->idletimer);
}

void nr_stop_heartbeat(struct sock *sk)
{
        sk_stop_timer(sk, &sk->sk_timer);
}

int nr_t1timer_running(struct sock *sk)
{
        return timer_pending(&nr_sk(sk)->t1timer);
}

static void nr_heartbeat_expiry(struct timer_list *t)
{
        struct sock *sk = from_timer(sk, t, sk_timer);
        struct nr_sock *nr = nr_sk(sk);

        bh_lock_sock(sk);
        switch (nr->state) {
        case NR_STATE_0:
                /* Magic here: If we listen() and a new link dies before it
                   is accepted() it isn't 'dead' so doesn't get removed. */
                if (sock_flag(sk, SOCK_DESTROY) ||
                    (sk->sk_state == TCP_LISTEN && sock_flag(sk, SOCK_DEAD))) {
                        sock_hold(sk);
                        bh_unlock_sock(sk);
                        nr_destroy_socket(sk);
                        sock_put(sk);
                        return;
                }
                break;

        case NR_STATE_3:
                /*
                 * Check for the state of the receive buffer.
                 */
                if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf / 2) &&
                    (nr->condition & NR_COND_OWN_RX_BUSY)) {
                        nr->condition &= ~NR_COND_OWN_RX_BUSY;
                        nr->condition &= ~NR_COND_ACK_PENDING;
                        nr->vl         = nr->vr;
                        nr_write_internal(sk, NR_INFOACK);
                        break;
                }
                break;
        }

        nr_start_heartbeat(sk);
        bh_unlock_sock(sk);
}

static void nr_t2timer_expiry(struct timer_list *t)
{
        struct nr_sock *nr = from_timer(nr, t, t2timer);
        struct sock *sk = &nr->sock;

        bh_lock_sock(sk);
        if (nr->condition & NR_COND_ACK_PENDING) {
                nr->condition &= ~NR_COND_ACK_PENDING;
                nr_enquiry_response(sk);
        }
        bh_unlock_sock(sk);
}

static void nr_t4timer_expiry(struct timer_list *t)
{
        struct nr_sock *nr = from_timer(nr, t, t4timer);
        struct sock *sk = &nr->sock;

        bh_lock_sock(sk);
        nr_sk(sk)->condition &= ~NR_COND_PEER_RX_BUSY;
        bh_unlock_sock(sk);
}

static void nr_idletimer_expiry(struct timer_list *t)
{
        struct nr_sock *nr = from_timer(nr, t, idletimer);
        struct sock *sk = &nr->sock;

        bh_lock_sock(sk);

        nr_clear_queues(sk);

        nr->n2count = 0;
        nr_write_internal(sk, NR_DISCREQ);
        nr->state = NR_STATE_2;

        nr_start_t1timer(sk);
        nr_stop_t2timer(sk);
        nr_stop_t4timer(sk);

        sk->sk_state     = TCP_CLOSE;
        sk->sk_err       = 0;
        sk->sk_shutdown |= SEND_SHUTDOWN;

        if (!sock_flag(sk, SOCK_DEAD)) {
                sk->sk_state_change(sk);
                sock_set_flag(sk, SOCK_DEAD);
        }
        bh_unlock_sock(sk);
}

static void nr_t1timer_expiry(struct timer_list *t)
{
        struct nr_sock *nr = from_timer(nr, t, t1timer);
        struct sock *sk = &nr->sock;

        bh_lock_sock(sk);
        switch (nr->state) {
        case NR_STATE_1:
                if (nr->n2count == nr->n2) {
                        nr_disconnect(sk, ETIMEDOUT);
                        bh_unlock_sock(sk);
                        return;
                } else {
                        nr->n2count++;
                        nr_write_internal(sk, NR_CONNREQ);
                }
                break;

        case NR_STATE_2:
                if (nr->n2count == nr->n2) {
                        nr_disconnect(sk, ETIMEDOUT);
                        bh_unlock_sock(sk);
                        return;
                } else {
                        nr->n2count++;
                        nr_write_internal(sk, NR_DISCREQ);
                }
                break;

        case NR_STATE_3:
                if (nr->n2count == nr->n2) {
                        nr_disconnect(sk, ETIMEDOUT);
                        bh_unlock_sock(sk);
                        return;
                } else {
                        nr->n2count++;
                        nr_requeue_frames(sk);
                }
                break;
        }

        nr_start_t1timer(sk);
        bh_unlock_sock(sk);
}