// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 */
#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 <linux/slab.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <net/rose.h>

static void rose_ftimer_expiry(struct timer_list *);
static void rose_t0timer_expiry(struct timer_list *);

static void rose_transmit_restart_confirmation(struct rose_neigh *neigh);
static void rose_transmit_restart_request(struct rose_neigh *neigh);

void rose_start_ftimer(struct rose_neigh *neigh)
{
        del_timer(&neigh->ftimer);

        neigh->ftimer.function = rose_ftimer_expiry;
        neigh->ftimer.expires  =
                jiffies + msecs_to_jiffies(sysctl_rose_link_fail_timeout);

        add_timer(&neigh->ftimer);
}

static void rose_start_t0timer(struct rose_neigh *neigh)
{
        del_timer(&neigh->t0timer);

        neigh->t0timer.function = rose_t0timer_expiry;
        neigh->t0timer.expires  =
                jiffies + msecs_to_jiffies(sysctl_rose_restart_request_timeout);

        add_timer(&neigh->t0timer);
}

void rose_stop_ftimer(struct rose_neigh *neigh)
{
        del_timer(&neigh->ftimer);
}

void rose_stop_t0timer(struct rose_neigh *neigh)
{
        del_timer(&neigh->t0timer);
}

int rose_ftimer_running(struct rose_neigh *neigh)
{
        return timer_pending(&neigh->ftimer);
}

static int rose_t0timer_running(struct rose_neigh *neigh)
{
        return timer_pending(&neigh->t0timer);
}

static void rose_ftimer_expiry(struct timer_list *t)
{
}

static void rose_t0timer_expiry(struct timer_list *t)
{
        struct rose_neigh *neigh = from_timer(neigh, t, t0timer);

        rose_transmit_restart_request(neigh);

        neigh->dce_mode = 0;

        rose_start_t0timer(neigh);
}

/*
 *      Interface to ax25_send_frame. Changes my level 2 callsign depending
 *      on whether we have a global ROSE callsign or use the default port
 *      callsign.
 */
static int rose_send_frame(struct sk_buff *skb, struct rose_neigh *neigh)
{
        const ax25_address *rose_call;
        ax25_cb *ax25s;

        if (ax25cmp(&rose_callsign, &null_ax25_address) == 0)
                rose_call = (const ax25_address *)neigh->dev->dev_addr;
        else
                rose_call = &rose_callsign;

        ax25s = neigh->ax25;
        neigh->ax25 = ax25_send_frame(skb, 260, rose_call, &neigh->callsign, neigh->digipeat, neigh->dev);
        if (ax25s)
                ax25_cb_put(ax25s);

        return neigh->ax25 != NULL;
}

/*
 *      Interface to ax25_link_up. Changes my level 2 callsign depending
 *      on whether we have a global ROSE callsign or use the default port
 *      callsign.
 */
static int rose_link_up(struct rose_neigh *neigh)
{
        const ax25_address *rose_call;
        ax25_cb *ax25s;

        if (ax25cmp(&rose_callsign, &null_ax25_address) == 0)
                rose_call = (const ax25_address *)neigh->dev->dev_addr;
        else
                rose_call = &rose_callsign;

        ax25s = neigh->ax25;
        neigh->ax25 = ax25_find_cb(rose_call, &neigh->callsign, neigh->digipeat, neigh->dev);
        if (ax25s)
                ax25_cb_put(ax25s);

        return neigh->ax25 != NULL;
}

/*
 *      This handles all restart and diagnostic frames.
 */
void rose_link_rx_restart(struct sk_buff *skb, struct rose_neigh *neigh, unsigned short frametype)
{
        struct sk_buff *skbn;

        switch (frametype) {
        case ROSE_RESTART_REQUEST:
                rose_stop_t0timer(neigh);
                neigh->restarted = 1;
                neigh->dce_mode  = (skb->data[3] == ROSE_DTE_ORIGINATED);
                rose_transmit_restart_confirmation(neigh);
                break;

        case ROSE_RESTART_CONFIRMATION:
                rose_stop_t0timer(neigh);
                neigh->restarted = 1;
                break;

        case ROSE_DIAGNOSTIC:
                pr_warn("ROSE: received diagnostic #%d - %3ph\n", skb->data[3],
                        skb->data + 4);
                break;

        default:
                printk(KERN_WARNING "ROSE: received unknown %02X with LCI 000\n", frametype);
                break;
        }

        if (neigh->restarted) {
                while ((skbn = skb_dequeue(&neigh->queue)) != NULL)
                        if (!rose_send_frame(skbn, neigh))
                                kfree_skb(skbn);
        }
}

/*
 *      This routine is called when a Restart Request is needed
 */
static void rose_transmit_restart_request(struct rose_neigh *neigh)
{
        struct sk_buff *skb;
        unsigned char *dptr;
        int len;

        len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + ROSE_MIN_LEN + 3;

        if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
                return;

        skb_reserve(skb, AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN);

        dptr = skb_put(skb, ROSE_MIN_LEN + 3);

        *dptr++ = AX25_P_ROSE;
        *dptr++ = ROSE_GFI;
        *dptr++ = 0x00;
        *dptr++ = ROSE_RESTART_REQUEST;
        *dptr++ = ROSE_DTE_ORIGINATED;
        *dptr++ = 0;

        if (!rose_send_frame(skb, neigh))
                kfree_skb(skb);
}

/*
 * This routine is called when a Restart Confirmation is needed
 */
static void rose_transmit_restart_confirmation(struct rose_neigh *neigh)
{
        struct sk_buff *skb;
        unsigned char *dptr;
        int len;

        len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + ROSE_MIN_LEN + 1;

        if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
                return;

        skb_reserve(skb, AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN);

        dptr = skb_put(skb, ROSE_MIN_LEN + 1);

        *dptr++ = AX25_P_ROSE;
        *dptr++ = ROSE_GFI;
        *dptr++ = 0x00;
        *dptr++ = ROSE_RESTART_CONFIRMATION;

        if (!rose_send_frame(skb, neigh))
                kfree_skb(skb);
}

/*
 * This routine is called when a Clear Request is needed outside of the context
 * of a connected socket.
 */
void rose_transmit_clear_request(struct rose_neigh *neigh, unsigned int lci, unsigned char cause, unsigned char diagnostic)
{
        struct sk_buff *skb;
        unsigned char *dptr;
        int len;

        len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + ROSE_MIN_LEN + 3;

        if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
                return;

        skb_reserve(skb, AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN);

        dptr = skb_put(skb, ROSE_MIN_LEN + 3);

        *dptr++ = AX25_P_ROSE;
        *dptr++ = ((lci >> 8) & 0x0F) | ROSE_GFI;
        *dptr++ = ((lci >> 0) & 0xFF);
        *dptr++ = ROSE_CLEAR_REQUEST;
        *dptr++ = cause;
        *dptr++ = diagnostic;

        if (!rose_send_frame(skb, neigh))
                kfree_skb(skb);
}

void rose_transmit_link(struct sk_buff *skb, struct rose_neigh *neigh)
{
        unsigned char *dptr;

        if (neigh->loopback) {
                rose_loopback_queue(skb, neigh);
                return;
        }

        if (!rose_link_up(neigh))
                neigh->restarted = 0;

        dptr = skb_push(skb, 1);
        *dptr++ = AX25_P_ROSE;

        if (neigh->restarted) {
                if (!rose_send_frame(skb, neigh))
                        kfree_skb(skb);
        } else {
                skb_queue_tail(&neigh->queue, skb);

                if (!rose_t0timer_running(neigh)) {
                        rose_transmit_restart_request(neigh);
                        neigh->dce_mode = 0;
                        rose_start_t0timer(neigh);
                }
        }
}