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/*

 *      X.25 Packet Layer release 002

 *

 *      This is ALPHA test software. This code may break your machine, randomly fail to work with new

 *      releases, misbehave and/or generally screw up. It might even work.

 *

 *      This code REQUIRES 2.1.15 or higher

 *

 *      This module:

 *              This module is free software; you can redistribute it and/or

 *              modify it under the terms of the GNU General Public License

 *              as published by the Free Software Foundation; either version

 *              2 of the License, or (at your option) any later version.

 *

 *      History

 *      X.25 001        Jonathan Naylor Started coding.

 *      2000-09-04      Henner Eisen    Prevent freeing a dangling skb.

 */

#include <linux/kernel.h>

#include <linux/netdevice.h>

#include <linux/skbuff.h>

#include <net/sock.h>

#include <linux/if_arp.h>

#include <net/x25.h>

static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)

{

        struct sock *sk;

        unsigned short frametype;

        unsigned int lci;

        frametype = skb->data[2];

        lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);

        /*

         *      LCI of zero is always for us, and its always a link control

         *      frame.

         */

        if (lci == 0) {

                x25_link_control(skb, nb, frametype);

                return 0;

        }

        /*

         *      Find an existing socket.

         */

        if ((sk = x25_find_socket(lci, nb)) != NULL) {

                int queued = 1;

                skb_reset_transport_header(skb);

                bh_lock_sock(sk);

                if (!sock_owned_by_user(sk)) {

                        queued = x25_process_rx_frame(sk, skb);

                } else {

                        sk_add_backlog(sk, skb);

                }

                bh_unlock_sock(sk);

                sock_put(sk);

                return queued;

        }

        /*

         *      Is is a Call Request ? if so process it.

         */

        if (frametype == X25_CALL_REQUEST)

                return x25_rx_call_request(skb, nb, lci);

        /*

         *      Its not a Call Request, nor is it a control frame.

         *      Can we forward it?

         */

        if (x25_forward_data(lci, nb, skb)) {

                if (frametype == X25_CLEAR_CONFIRMATION) {

                        x25_clear_forward_by_lci(lci);

                }

                kfree_skb(skb);

                return 1;

        }

/*

        x25_transmit_clear_request(nb, lci, 0x0D);

*/

        if (frametype != X25_CLEAR_CONFIRMATION)

                printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype);

        return 0;

}

int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,

                           struct packet_type *ptype, struct net_device *orig_dev)

{

        struct sk_buff *nskb;

        struct x25_neigh *nb;

        if (dev->nd_net != &init_net)

                goto drop;

        nskb = skb_copy(skb, GFP_ATOMIC);

        if (!nskb)

                goto drop;

        kfree_skb(skb);

        skb = nskb;

        /*

         * Packet received from unrecognised device, throw it away.

         */

        nb = x25_get_neigh(dev);

        if (!nb) {

                printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name);

                goto drop;

        }

        switch (skb->data[0]) {

                case 0x00:

                        skb_pull(skb, 1);

                        if (x25_receive_data(skb, nb)) {

                                x25_neigh_put(nb);

                                goto out;

                        }

                        break;

                case 0x01:

                        x25_link_established(nb);

                        break;

                case 0x02:

                        x25_link_terminated(nb);

                        break;

        }

        x25_neigh_put(nb);

drop:

        kfree_skb(skb);

out:

        return 0;

}

void x25_establish_link(struct x25_neigh *nb)

{

        struct sk_buff *skb;

        unsigned char *ptr;

        switch (nb->dev->type) {

                case ARPHRD_X25:

                        if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {

                                printk(KERN_ERR "x25_dev: out of memory\n");

                                return;

                        }

                        ptr  = skb_put(skb, 1);

                        *ptr = 0x01;

                        break;

#if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)

                case ARPHRD_ETHER:

                        return;

#endif

                default:

                        return;

        }

        skb->protocol = htons(ETH_P_X25);

        skb->dev      = nb->dev;

        dev_queue_xmit(skb);

}

void x25_terminate_link(struct x25_neigh *nb)

{

        struct sk_buff *skb;

        unsigned char *ptr;

#if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)

        if (nb->dev->type == ARPHRD_ETHER)

                return;

#endif

        if (nb->dev->type != ARPHRD_X25)

                return;

        skb = alloc_skb(1, GFP_ATOMIC);

        if (!skb) {

                printk(KERN_ERR "x25_dev: out of memory\n");

                return;

        }

        ptr  = skb_put(skb, 1);

        *ptr = 0x02;

        skb->protocol = htons(ETH_P_X25);

        skb->dev      = nb->dev;

        dev_queue_xmit(skb);

}

void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)

{

        unsigned char *dptr;

        skb_reset_network_header(skb);

        switch (nb->dev->type) {

                case ARPHRD_X25:

                        dptr  = skb_push(skb, 1);

                        *dptr = 0x00;

                        break;

#if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)

                case ARPHRD_ETHER:

                        kfree_skb(skb);

                        return;

#endif

                default:

                        kfree_skb(skb);

                        return;

        }

        skb->protocol = htons(ETH_P_X25);

        skb->dev      = nb->dev;

        dev_queue_xmit(skb);

}