/*
 *      ipddp.c: IP to Appletalk-IP Encapsulation driver for Linux
 *               Appletalk-IP to IP Decapsulation driver for Linux
 *
 *      Authors:
 *      - DDP-IP Encap by: Bradford W. Johnson <johns393@maroon.tc.umn.edu>
 *      - DDP-IP Decap by: Jay Schulist <jschlst@samba.org>
 *
 *      Derived from:
 *      - Almost all code already existed in net/appletalk/ddp.c I just
 *        moved/reorginized it into a driver file. Original IP-over-DDP code
 *        was done by Bradford W. Johnson <johns393@maroon.tc.umn.edu>
 *      - skeleton.c: A network driver outline for linux.
 *        Written 1993-94 by Donald Becker.
 *      - dummy.c: A dummy net driver. By Nick Holloway.
 *      - MacGate: A user space Daemon for Appletalk-IP Decap for
 *        Linux by Jay Schulist <jschlst@samba.org>
 *
 *      Copyright 1993 United States Government as represented by the
 *      Director, National Security Agency.
 *
 *      This software may be used and distributed according to the terms
 *      of the GNU General Public License, incorporated herein by reference.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ip.h>
#include <linux/atalk.h>
#include <linux/if_arp.h>
#include <linux/slab.h>
#include <net/route.h>
#include <asm/uaccess.h>

#include "ipddp.h"              /* Our stuff */

static const char version[] = KERN_INFO "ipddp.c:v0.01 8/28/97 Bradford W. Johnson <johns393@maroon.tc.umn.edu>\n";

static struct ipddp_route *ipddp_route_list;
static DEFINE_SPINLOCK(ipddp_route_lock);

#ifdef CONFIG_IPDDP_ENCAP
static int ipddp_mode = IPDDP_ENCAP;
#else
static int ipddp_mode = IPDDP_DECAP;
#endif

/* Index to functions, as function prototypes. */
static netdev_tx_t ipddp_xmit(struct sk_buff *skb,
                                    struct net_device *dev);
static int ipddp_create(struct ipddp_route *new_rt);
static int ipddp_delete(struct ipddp_route *rt);
static struct ipddp_route* __ipddp_find_route(struct ipddp_route *rt);
static int ipddp_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd);

static const struct net_device_ops ipddp_netdev_ops = {
        .ndo_start_xmit         = ipddp_xmit,
        .ndo_do_ioctl           = ipddp_ioctl,
        .ndo_change_mtu         = eth_change_mtu,
        .ndo_set_mac_address    = eth_mac_addr,
        .ndo_validate_addr      = eth_validate_addr,
};

static struct net_device * __init ipddp_init(void)
{
        static unsigned version_printed;
        struct net_device *dev;
        int err;

        dev = alloc_etherdev(0);
        if (!dev)
                return ERR_PTR(-ENOMEM);

        dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
        strcpy(dev->name, "ipddp%d");

        if (version_printed++ == 0)
                printk(version);

        /* Initialize the device structure. */
        dev->netdev_ops = &ipddp_netdev_ops;

        dev->type = ARPHRD_IPDDP;               /* IP over DDP tunnel */
        dev->mtu = 585;
        dev->flags |= IFF_NOARP;

        /*
         *      The worst case header we will need is currently a
         *      ethernet header (14 bytes) and a ddp header (sizeof ddpehdr+1)
         *      We send over SNAP so that takes another 8 bytes.
         */
        dev->hard_header_len = 14+8+sizeof(struct ddpehdr)+1;

        err = register_netdev(dev);
        if (err) {
                free_netdev(dev);
                return ERR_PTR(err);
        }

        /* Let the user now what mode we are in */
        if(ipddp_mode == IPDDP_ENCAP)
                printk("%s: Appletalk-IP Encap. mode by Bradford W. Johnson <johns393@maroon.tc.umn.edu>\n", 
                        dev->name);
        if(ipddp_mode == IPDDP_DECAP)
                printk("%s: Appletalk-IP Decap. mode by Jay Schulist <jschlst@samba.org>\n", 
                        dev->name);

        return dev;
}


/*
 * Transmit LLAP/ELAP frame using aarp_send_ddp.
 */
static netdev_tx_t ipddp_xmit(struct sk_buff *skb, struct net_device *dev)
{
        __be32 paddr = skb_rtable(skb)->rt_gateway;
        struct ddpehdr *ddp;
        struct ipddp_route *rt;
        struct atalk_addr *our_addr;

        spin_lock(&ipddp_route_lock);

        /*
         * Find appropriate route to use, based only on IP number.
         */
        for(rt = ipddp_route_list; rt != NULL; rt = rt->next)
        {
                if(rt->ip == paddr)
                        break;
        }
        if(rt == NULL) {
                spin_unlock(&ipddp_route_lock);
                return NETDEV_TX_OK;
        }

        our_addr = atalk_find_dev_addr(rt->dev);

        if(ipddp_mode == IPDDP_DECAP)
                /* 
                 * Pull off the excess room that should not be there.
                 * This is due to a hard-header problem. This is the
                 * quick fix for now though, till it breaks.
                 */
                skb_pull(skb, 35-(sizeof(struct ddpehdr)+1));

        /* Create the Extended DDP header */
        ddp = (struct ddpehdr *)skb->data;
        ddp->deh_len_hops = htons(skb->len + (1<<10));
        ddp->deh_sum = 0;

        /*
         * For Localtalk we need aarp_send_ddp to strip the
         * long DDP header and place a shot DDP header on it.
         */
        if(rt->dev->type == ARPHRD_LOCALTLK)
        {
                ddp->deh_dnet  = 0;   /* FIXME more hops?? */
                ddp->deh_snet  = 0;
        }
        else
        {
                ddp->deh_dnet  = rt->at.s_net;   /* FIXME more hops?? */
                ddp->deh_snet  = our_addr->s_net;
        }
        ddp->deh_dnode = rt->at.s_node;
        ddp->deh_snode = our_addr->s_node;
        ddp->deh_dport = 72;
        ddp->deh_sport = 72;

        *((__u8 *)(ddp+1)) = 22;                /* ddp type = IP */

        skb->protocol = htons(ETH_P_ATALK);     /* Protocol has changed */

        dev->stats.tx_packets++;
        dev->stats.tx_bytes += skb->len;

        aarp_send_ddp(rt->dev, skb, &rt->at, NULL);

        spin_unlock(&ipddp_route_lock);

        return NETDEV_TX_OK;
}

/*
 * Create a routing entry. We first verify that the
 * record does not already exist. If it does we return -EEXIST
 */
static int ipddp_create(struct ipddp_route *new_rt)
{
        struct ipddp_route *rt = kmalloc(sizeof(*rt), GFP_KERNEL);

        if (rt == NULL)
                return -ENOMEM;

        rt->ip = new_rt->ip;
        rt->at = new_rt->at;
        rt->next = NULL;
        if ((rt->dev = atrtr_get_dev(&rt->at)) == NULL) {
                kfree(rt);
                return -ENETUNREACH;
        }

        spin_lock_bh(&ipddp_route_lock);
        if (__ipddp_find_route(rt)) {
                spin_unlock_bh(&ipddp_route_lock);
                kfree(rt);
                return -EEXIST;
        }

        rt->next = ipddp_route_list;
        ipddp_route_list = rt;

        spin_unlock_bh(&ipddp_route_lock);

        return 0;
}

/*
 * Delete a route, we only delete a FULL match.
 * If route does not exist we return -ENOENT.
 */
static int ipddp_delete(struct ipddp_route *rt)
{
        struct ipddp_route **r = &ipddp_route_list;
        struct ipddp_route *tmp;

        spin_lock_bh(&ipddp_route_lock);
        while((tmp = *r) != NULL)
        {
                if(tmp->ip == rt->ip &&
                   tmp->at.s_net == rt->at.s_net &&
                   tmp->at.s_node == rt->at.s_node)
                {
                        *r = tmp->next;
                        spin_unlock_bh(&ipddp_route_lock);
                        kfree(tmp);
                        return 0;
                }
                r = &tmp->next;
        }

        spin_unlock_bh(&ipddp_route_lock);
        return -ENOENT;
}

/*
 * Find a routing entry, we only return a FULL match
 */
static struct ipddp_route* __ipddp_find_route(struct ipddp_route *rt)
{
        struct ipddp_route *f;

        for(f = ipddp_route_list; f != NULL; f = f->next)
        {
                if(f->ip == rt->ip &&
                   f->at.s_net == rt->at.s_net &&
                   f->at.s_node == rt->at.s_node)
                        return f;
        }

        return NULL;
}

static int ipddp_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
        struct ipddp_route __user *rt = ifr->ifr_data;
        struct ipddp_route rcp, rcp2, *rp;

        if(!capable(CAP_NET_ADMIN))
                return -EPERM;

        if(copy_from_user(&rcp, rt, sizeof(rcp)))
                return -EFAULT;

        switch(cmd)
        {
                case SIOCADDIPDDPRT:
                        return ipddp_create(&rcp);

                case SIOCFINDIPDDPRT:
                        spin_lock_bh(&ipddp_route_lock);
                        rp = __ipddp_find_route(&rcp);
                        if (rp)
                                memcpy(&rcp2, rp, sizeof(rcp2));
                        spin_unlock_bh(&ipddp_route_lock);

                        if (rp) {
                                if (copy_to_user(rt, &rcp2,
                                                 sizeof(struct ipddp_route)))
                                        return -EFAULT;
                                return 0;
                        } else
                                return -ENOENT;

                case SIOCDELIPDDPRT:
                        return ipddp_delete(&rcp);

                default:
                        return -EINVAL;
        }
}

static struct net_device *dev_ipddp;

MODULE_LICENSE("GPL");
module_param(ipddp_mode, int, 0);

static int __init ipddp_init_module(void)
{
        dev_ipddp = ipddp_init();
        if (IS_ERR(dev_ipddp))
                return PTR_ERR(dev_ipddp);
        return 0;
}

static void __exit ipddp_cleanup_module(void)
{
        struct ipddp_route *p;

        unregister_netdev(dev_ipddp);
        free_netdev(dev_ipddp);

        while (ipddp_route_list) {
                p = ipddp_route_list->next;
                kfree(ipddp_route_list);
                ipddp_route_list = p;
        }
}

module_init(ipddp_init_module);
module_exit(ipddp_cleanup_module);