// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *
 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 */
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/socket.h>
#include <linux/timer.h>
#include <net/ax25.h>
#include <linux/skbuff.h>
#include <net/rose.h>
#include <linux/init.h>

static struct sk_buff_head loopback_queue;
#define ROSE_LOOPBACK_LIMIT 1000
static struct timer_list loopback_timer;

static void rose_set_loopback_timer(void);
static void rose_loopback_timer(struct timer_list *unused);

void rose_loopback_init(void)
{
        skb_queue_head_init(&loopback_queue);

        timer_setup(&loopback_timer, rose_loopback_timer, 0);
}

static int rose_loopback_running(void)
{
        return timer_pending(&loopback_timer);
}

int rose_loopback_queue(struct sk_buff *skb, struct rose_neigh *neigh)
{
        struct sk_buff *skbn = NULL;

        if (skb_queue_len(&loopback_queue) < ROSE_LOOPBACK_LIMIT)
                skbn = skb_clone(skb, GFP_ATOMIC);

        if (skbn) {
                consume_skb(skb);
                skb_queue_tail(&loopback_queue, skbn);

                if (!rose_loopback_running())
                        rose_set_loopback_timer();
        } else {
                kfree_skb(skb);
        }

        return 1;
}

static void rose_set_loopback_timer(void)
{
        mod_timer(&loopback_timer, jiffies + 10);
}

static void rose_loopback_timer(struct timer_list *unused)
{
        struct sk_buff *skb;
        struct net_device *dev;
        rose_address *dest;
        struct sock *sk;
        unsigned short frametype;
        unsigned int lci_i, lci_o;
        int count;

        for (count = 0; count < ROSE_LOOPBACK_LIMIT; count++) {
                skb = skb_dequeue(&loopback_queue);
                if (!skb)
                        return;
                if (skb->len < ROSE_MIN_LEN) {
                        kfree_skb(skb);
                        continue;
                }
                lci_i     = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
                frametype = skb->data[2];
                if (frametype == ROSE_CALL_REQUEST &&
                    (skb->len <= ROSE_CALL_REQ_FACILITIES_OFF ||
                     skb->data[ROSE_CALL_REQ_ADDR_LEN_OFF] !=
                     ROSE_CALL_REQ_ADDR_LEN_VAL)) {
                        kfree_skb(skb);
                        continue;
                }
                dest      = (rose_address *)(skb->data + ROSE_CALL_REQ_DEST_ADDR_OFF);
                lci_o     = ROSE_DEFAULT_MAXVC + 1 - lci_i;

                skb_reset_transport_header(skb);

                sk = rose_find_socket(lci_o, rose_loopback_neigh);
                if (sk) {
                        if (rose_process_rx_frame(sk, skb) == 0)
                                kfree_skb(skb);
                        continue;
                }

                if (frametype == ROSE_CALL_REQUEST) {
                        if (!rose_loopback_neigh->dev &&
                            !rose_loopback_neigh->loopback) {
                                kfree_skb(skb);
                                continue;
                        }

                        dev = rose_dev_get(dest);
                        if (!dev) {
                                kfree_skb(skb);
                                continue;
                        }

                        if (rose_rx_call_request(skb, dev, rose_loopback_neigh, lci_o) == 0) {
                                dev_put(dev);
                                kfree_skb(skb);
                        }
                } else {
                        kfree_skb(skb);
                }
        }
        if (!skb_queue_empty(&loopback_queue))
                mod_timer(&loopback_timer, jiffies + 1);
}

void __exit rose_loopback_clear(void)
{
        struct sk_buff *skb;

        timer_delete(&loopback_timer);

        while ((skb = skb_dequeue(&loopback_queue)) != NULL) {
                skb->sk = NULL;
                kfree_skb(skb);
        }
}