// 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/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <net/rose.h>

static void rose_heartbeat_expiry(struct timer_list *t);
static void rose_timer_expiry(struct timer_list *);
static void rose_idletimer_expiry(struct timer_list *);

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

        sk->sk_timer.function = rose_heartbeat_expiry;
        sk->sk_timer.expires  = jiffies + 5 * HZ;

        sk_reset_timer(sk, &sk->sk_timer, sk->sk_timer.expires);
}

void rose_start_t1timer(struct sock *sk)
{
        struct rose_sock *rose = rose_sk(sk);

        sk_stop_timer(sk, &rose->timer);

        rose->timer.function = rose_timer_expiry;
        rose->timer.expires  = jiffies + rose->t1;

        sk_reset_timer(sk, &rose->timer, rose->timer.expires);
}

void rose_start_t2timer(struct sock *sk)
{
        struct rose_sock *rose = rose_sk(sk);

        sk_stop_timer(sk, &rose->timer);

        rose->timer.function = rose_timer_expiry;
        rose->timer.expires  = jiffies + rose->t2;

        sk_reset_timer(sk, &rose->timer, rose->timer.expires);
}

void rose_start_t3timer(struct sock *sk)
{
        struct rose_sock *rose = rose_sk(sk);

        sk_stop_timer(sk, &rose->timer);

        rose->timer.function = rose_timer_expiry;
        rose->timer.expires  = jiffies + rose->t3;

        sk_reset_timer(sk, &rose->timer, rose->timer.expires);
}

void rose_start_hbtimer(struct sock *sk)
{
        struct rose_sock *rose = rose_sk(sk);

        sk_stop_timer(sk, &rose->timer);

        rose->timer.function = rose_timer_expiry;
        rose->timer.expires  = jiffies + rose->hb;

        sk_reset_timer(sk, &rose->timer, rose->timer.expires);
}

void rose_start_idletimer(struct sock *sk)
{
        struct rose_sock *rose = rose_sk(sk);

        sk_stop_timer(sk, &rose->idletimer);

        if (rose->idle > 0) {
                rose->idletimer.function = rose_idletimer_expiry;
                rose->idletimer.expires  = jiffies + rose->idle;

                sk_reset_timer(sk, &rose->idletimer, rose->idletimer.expires);
        }
}

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

void rose_stop_timer(struct sock *sk)
{
        sk_stop_timer(sk, &rose_sk(sk)->timer);
}

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

static void rose_heartbeat_expiry(struct timer_list *t)
{
        struct sock *sk = timer_container_of(sk, t, sk_timer);
        struct rose_sock *rose = rose_sk(sk);

        bh_lock_sock(sk);
        if (sock_owned_by_user(sk)) {
                sk_reset_timer(sk, &sk->sk_timer, jiffies + HZ/20);
                goto out;
        }
        switch (rose->state) {
        case ROSE_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))) {
                        bh_unlock_sock(sk);
                        rose_destroy_socket(sk);
                        sock_put(sk);
                        return;
                }
                break;

        case ROSE_STATE_3:
                /*
                 * Check for the state of the receive buffer.
                 */
                if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf / 2) &&
                    (rose->condition & ROSE_COND_OWN_RX_BUSY)) {
                        rose->condition &= ~ROSE_COND_OWN_RX_BUSY;
                        rose->condition &= ~ROSE_COND_ACK_PENDING;
                        rose->vl         = rose->vr;
                        rose_write_internal(sk, ROSE_RR);
                        rose_stop_timer(sk);    /* HB */
                        break;
                }
                break;
        }

        rose_start_heartbeat(sk);
out:
        bh_unlock_sock(sk);
        sock_put(sk);
}

static void rose_timer_expiry(struct timer_list *t)
{
        struct rose_sock *rose = timer_container_of(rose, t, timer);
        struct sock *sk = &rose->sock;

        bh_lock_sock(sk);
        if (sock_owned_by_user(sk)) {
                sk_reset_timer(sk, &rose->timer, jiffies + HZ/20);
                goto out;
        }
        switch (rose->state) {
        case ROSE_STATE_1:      /* T1 */
        case ROSE_STATE_4:      /* T2 */
                rose_write_internal(sk, ROSE_CLEAR_REQUEST);
                rose->state = ROSE_STATE_2;
                rose_start_t3timer(sk);
                break;

        case ROSE_STATE_2:      /* T3 */
                rose_neigh_put(rose->neighbour);
                rose_disconnect(sk, ETIMEDOUT, -1, -1);
                break;

        case ROSE_STATE_3:      /* HB */
                if (rose->condition & ROSE_COND_ACK_PENDING) {
                        rose->condition &= ~ROSE_COND_ACK_PENDING;
                        rose_enquiry_response(sk);
                }
                break;
        }
out:
        bh_unlock_sock(sk);
        sock_put(sk);
}

static void rose_idletimer_expiry(struct timer_list *t)
{
        struct rose_sock *rose = timer_container_of(rose, t, idletimer);
        struct sock *sk = &rose->sock;

        bh_lock_sock(sk);
        if (sock_owned_by_user(sk)) {
                sk_reset_timer(sk, &rose->idletimer, jiffies + HZ/20);
                goto out;
        }
        rose_clear_queues(sk);

        rose_write_internal(sk, ROSE_CLEAR_REQUEST);
        rose_sk(sk)->state = ROSE_STATE_2;

        rose_start_t3timer(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);
        }
out:
        bh_unlock_sock(sk);
        sock_put(sk);
}