x25_forward.c

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/*
 *  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
 *  03-01-2007  Added forwarding for x.25   Andrew Hendry
 */
#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <net/x25.h>

LIST_HEAD(x25_forward_list);
DEFINE_RWLOCK(x25_forward_list_lock);

int x25_forward_call(struct x25_address *dest_addr, struct x25_neigh *from,
            struct sk_buff *skb, int lci)
{
    struct x25_route *rt;
    struct x25_neigh *neigh_new = NULL;
    struct list_head *entry;
    struct x25_forward *x25_frwd, *new_frwd;
    struct sk_buff *skbn;
    short same_lci = 0;
    int rc = 0;

    if ((rt = x25_get_route(dest_addr)) == NULL)
        goto out_no_route;

    if ((neigh_new = x25_get_neigh(rt->dev)) == NULL) {
        /* This shouldn't happen, if it occurs somehow
         * do something sensible
         */
        goto out_put_route;
    }

    /* Avoid a loop. This is the normal exit path for a
     * system with only one x.25 iface and default route
     */
    if (rt->dev == from->dev) {
        goto out_put_nb;
    }

    /* Remote end sending a call request on an already
     * established LCI? It shouldn't happen, just in case..
     */
    read_lock_bh(&x25_forward_list_lock);
    list_for_each(entry, &x25_forward_list) {
        x25_frwd = list_entry(entry, struct x25_forward, node);
        if (x25_frwd->lci == lci) {
            printk(KERN_WARNING "X.25: call request for lci which is already registered!, transmitting but not registering new pair\n");
            same_lci = 1;
        }
    }
    read_unlock_bh(&x25_forward_list_lock);

    /* Save the forwarding details for future traffic */
    if (!same_lci){
        if ((new_frwd = kmalloc(sizeof(struct x25_forward),
                        GFP_ATOMIC)) == NULL){
            rc = -ENOMEM;
            goto out_put_nb;
        }
        new_frwd->lci = lci;
        new_frwd->dev1 = rt->dev;
        new_frwd->dev2 = from->dev;
        write_lock_bh(&x25_forward_list_lock);
        list_add(&new_frwd->node, &x25_forward_list);
        write_unlock_bh(&x25_forward_list_lock);
    }

    /* Forward the call request */
    if ( (skbn = skb_clone(skb, GFP_ATOMIC)) == NULL){
        goto out_put_nb;
    }
    x25_transmit_link(skbn, neigh_new);
    rc = 1;


out_put_nb:
    x25_neigh_put(neigh_new);

out_put_route:
    x25_route_put(rt);

out_no_route:
    return rc;
}


int x25_forward_data(int lci, struct x25_neigh *from, struct sk_buff *skb) {

    struct x25_forward *frwd;
    struct list_head *entry;
    struct net_device *peer = NULL;
    struct x25_neigh *nb;
    struct sk_buff *skbn;
    int rc = 0;

    read_lock_bh(&x25_forward_list_lock);
    list_for_each(entry, &x25_forward_list) {
        frwd = list_entry(entry, struct x25_forward, node);
        if (frwd->lci == lci) {
            /* The call is established, either side can send */
            if (from->dev == frwd->dev1) {
                peer = frwd->dev2;
            } else {
                peer = frwd->dev1;
            }
            break;
        }
    }
    read_unlock_bh(&x25_forward_list_lock);

    if ( (nb = x25_get_neigh(peer)) == NULL)
        goto out;

    if ( (skbn = pskb_copy(skb, GFP_ATOMIC)) == NULL){
        goto output;

    }
    x25_transmit_link(skbn, nb);

    rc = 1;
output:
    x25_neigh_put(nb);
out:
    return rc;
}

void x25_clear_forward_by_lci(unsigned int lci)
{
    struct x25_forward *fwd;
    struct list_head *entry, *tmp;

    write_lock_bh(&x25_forward_list_lock);

    list_for_each_safe(entry, tmp, &x25_forward_list) {
        fwd = list_entry(entry, struct x25_forward, node);
        if (fwd->lci == lci) {
            list_del(&fwd->node);
            kfree(fwd);
        }
    }
    write_unlock_bh(&x25_forward_list_lock);
}


void x25_clear_forward_by_dev(struct net_device *dev)
{
    struct x25_forward *fwd;
    struct list_head *entry, *tmp;

    write_lock_bh(&x25_forward_list_lock);

    list_for_each_safe(entry, tmp, &x25_forward_list) {
        fwd = list_entry(entry, struct x25_forward, node);
        if ((fwd->dev1 == dev) || (fwd->dev2 == dev)){
            list_del(&fwd->node);
            kfree(fwd);
        }
    }
    write_unlock_bh(&x25_forward_list_lock);
}