/*
 *      An implementation of the Acorn Econet and AUN protocols.
 *      Philip Blundell <philb@gnu.org>
 *
 *      This program 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.
 *
 */

#include <linux/module.h>

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/in.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/if_ether.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/route.h>
#include <linux/inet.h>
#include <linux/etherdevice.h>
#include <linux/if_arp.h>
#include <linux/wireless.h>
#include <linux/skbuff.h>
#include <linux/udp.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <net/sock.h>
#include <net/inet_common.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/if_ec.h>
#include <net/udp.h>
#include <net/ip.h>
#include <linux/spinlock.h>
#include <linux/rcupdate.h>
#include <linux/bitops.h>
#include <linux/mutex.h>

#include <asm/uaccess.h>
#include <asm/system.h>

static const struct proto_ops econet_ops;
static struct hlist_head econet_sklist;
static DEFINE_SPINLOCK(econet_lock);
static DEFINE_MUTEX(econet_mutex);

/* Since there are only 256 possible network numbers (or fewer, depends
   how you count) it makes sense to use a simple lookup table. */
static struct net_device *net2dev_map[256];

#define EC_PORT_IP      0xd2

#ifdef CONFIG_ECONET_AUNUDP
static DEFINE_SPINLOCK(aun_queue_lock);
static struct socket *udpsock;
#define AUN_PORT        0x8000


struct aunhdr
{
        unsigned char code;             /* AUN magic protocol byte */
        unsigned char port;
        unsigned char cb;
        unsigned char pad;
        unsigned long handle;
};

static unsigned long aun_seq;

/* Queue of packets waiting to be transmitted. */
static struct sk_buff_head aun_queue;
static struct timer_list ab_cleanup_timer;

#endif          /* CONFIG_ECONET_AUNUDP */

/* Per-packet information */
struct ec_cb
{
        struct sockaddr_ec sec;
        unsigned long cookie;           /* Supplied by user. */
#ifdef CONFIG_ECONET_AUNUDP
        int done;
        unsigned long seq;              /* Sequencing */
        unsigned long timeout;          /* Timeout */
        unsigned long start;            /* jiffies */
#endif
#ifdef CONFIG_ECONET_NATIVE
        void (*sent)(struct sk_buff *, int result);
#endif
};

static void econet_remove_socket(struct hlist_head *list, struct sock *sk)
{
        spin_lock_bh(&econet_lock);
        sk_del_node_init(sk);
        spin_unlock_bh(&econet_lock);
}

static void econet_insert_socket(struct hlist_head *list, struct sock *sk)
{
        spin_lock_bh(&econet_lock);
        sk_add_node(sk, list);
        spin_unlock_bh(&econet_lock);
}

/*
 *      Pull a packet from our receive queue and hand it to the user.
 *      If necessary we block.
 */

static int econet_recvmsg(struct kiocb *iocb, struct socket *sock,
                          struct msghdr *msg, size_t len, int flags)
{
        struct sock *sk = sock->sk;
        struct sk_buff *skb;
        size_t copied;
        int err;

        msg->msg_namelen = sizeof(struct sockaddr_ec);

        mutex_lock(&econet_mutex);

        /*
         *      Call the generic datagram receiver. This handles all sorts
         *      of horrible races and re-entrancy so we can forget about it
         *      in the protocol layers.
         *
         *      Now it will return ENETDOWN, if device have just gone down,
         *      but then it will block.
         */

        skb=skb_recv_datagram(sk,flags,flags&MSG_DONTWAIT,&err);

        /*
         *      An error occurred so return it. Because skb_recv_datagram()
         *      handles the blocking we don't see and worry about blocking
         *      retries.
         */

        if(skb==NULL)
                goto out;

        /*
         *      You lose any data beyond the buffer you gave. If it worries a
         *      user program they can ask the device for its MTU anyway.
         */

        copied = skb->len;
        if (copied > len)
        {
                copied=len;
                msg->msg_flags|=MSG_TRUNC;
        }

        /* We can't use skb_copy_datagram here */
        err = memcpy_toiovec(msg->msg_iov, skb->data, copied);
        if (err)
                goto out_free;
        sk->sk_stamp = skb->tstamp;

        if (msg->msg_name)
                memcpy(msg->msg_name, skb->cb, msg->msg_namelen);

        /*
         *      Free or return the buffer as appropriate. Again this
         *      hides all the races and re-entrancy issues from us.
         */
        err = copied;

out_free:
        skb_free_datagram(sk, skb);
out:
        mutex_unlock(&econet_mutex);
        return err;
}

/*
 *      Bind an Econet socket.
 */

static int econet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
        struct sockaddr_ec *sec = (struct sockaddr_ec *)uaddr;
        struct sock *sk;
        struct econet_sock *eo;

        /*
         *      Check legality
         */

        if (addr_len < sizeof(struct sockaddr_ec) ||
            sec->sec_family != AF_ECONET)
                return -EINVAL;

        mutex_lock(&econet_mutex);

        sk = sock->sk;
        eo = ec_sk(sk);

        eo->cb      = sec->cb;
        eo->port    = sec->port;
        eo->station = sec->addr.station;
        eo->net     = sec->addr.net;

        mutex_unlock(&econet_mutex);

        return 0;
}

#if defined(CONFIG_ECONET_AUNUDP) || defined(CONFIG_ECONET_NATIVE)
/*
 *      Queue a transmit result for the user to be told about.
 */

static void tx_result(struct sock *sk, unsigned long cookie, int result)
{
        struct sk_buff *skb = alloc_skb(0, GFP_ATOMIC);
        struct ec_cb *eb;
        struct sockaddr_ec *sec;

        if (skb == NULL)
        {
                printk(KERN_DEBUG "ec: memory squeeze, transmit result dropped.\n");
                return;
        }

        eb = (struct ec_cb *)&skb->cb;
        sec = (struct sockaddr_ec *)&eb->sec;
        memset(sec, 0, sizeof(struct sockaddr_ec));
        sec->cookie = cookie;
        sec->type = ECTYPE_TRANSMIT_STATUS | result;
        sec->sec_family = AF_ECONET;

        if (sock_queue_rcv_skb(sk, skb) < 0)
                kfree_skb(skb);
}
#endif

#ifdef CONFIG_ECONET_NATIVE
/*
 *      Called by the Econet hardware driver when a packet transmit
 *      has completed.  Tell the user.
 */

static void ec_tx_done(struct sk_buff *skb, int result)
{
        struct ec_cb *eb = (struct ec_cb *)&skb->cb;
        tx_result(skb->sk, eb->cookie, result);
}
#endif

/*
 *      Send a packet.  We have to work out which device it's going out on
 *      and hence whether to use real Econet or the UDP emulation.
 */

static int econet_sendmsg(struct kiocb *iocb, struct socket *sock,
                          struct msghdr *msg, size_t len)
{
        struct sockaddr_ec *saddr=(struct sockaddr_ec *)msg->msg_name;
        struct net_device *dev;
        struct ec_addr addr;
        int err;
        unsigned char port, cb;
#if defined(CONFIG_ECONET_AUNUDP) || defined(CONFIG_ECONET_NATIVE)
        struct sock *sk = sock->sk;
        struct sk_buff *skb;
        struct ec_cb *eb;
#endif
#ifdef CONFIG_ECONET_AUNUDP
        struct msghdr udpmsg;
        struct iovec iov[2];
        struct aunhdr ah;
        struct sockaddr_in udpdest;
        __kernel_size_t size;
        mm_segment_t oldfs;
        char *userbuf;
#endif

        /*
         *      Check the flags.
         */

        if (msg->msg_flags & ~(MSG_DONTWAIT|MSG_CMSG_COMPAT))
                return -EINVAL;

        /*
         *      Get and verify the address.
         */

        mutex_lock(&econet_mutex);

        if (saddr == NULL || msg->msg_namelen < sizeof(struct sockaddr_ec)) {
                mutex_unlock(&econet_mutex);
                return -EINVAL;
        }
        addr.station = saddr->addr.station;
        addr.net = saddr->addr.net;
        port = saddr->port;
        cb = saddr->cb;

        /* Look for a device with the right network number. */
        dev = net2dev_map[addr.net];

        /* If not directly reachable, use some default */
        if (dev == NULL) {
                dev = net2dev_map[0];
                /* No interfaces at all? */
                if (dev == NULL) {
                        mutex_unlock(&econet_mutex);
                        return -ENETDOWN;
                }
        }

        if (dev->type == ARPHRD_ECONET) {
                /* Real hardware Econet.  We're not worthy etc. */
#ifdef CONFIG_ECONET_NATIVE
                unsigned short proto = 0;
                int res;

                if (len + 15 > dev->mtu) {
                        mutex_unlock(&econet_mutex);
                        return -EMSGSIZE;
                }

                dev_hold(dev);

                skb = sock_alloc_send_skb(sk, len+LL_ALLOCATED_SPACE(dev),
                                          msg->msg_flags & MSG_DONTWAIT, &err);
                if (skb==NULL)
                        goto out_unlock;

                skb_reserve(skb, LL_RESERVED_SPACE(dev));
                skb_reset_network_header(skb);

                eb = (struct ec_cb *)&skb->cb;

                eb->cookie = saddr->cookie;
                eb->sec = *saddr;
                eb->sent = ec_tx_done;

                err = -EINVAL;
                res = dev_hard_header(skb, dev, ntohs(proto), &addr, NULL, len);
                if (res < 0)
                        goto out_free;
                if (res > 0) {
                        struct ec_framehdr *fh;
                        /* Poke in our control byte and
                           port number.  Hack, hack.  */
                        fh = (struct ec_framehdr *)(skb->data);
                        fh->cb = cb;
                        fh->port = port;
                        if (sock->type != SOCK_DGRAM) {
                                skb_reset_tail_pointer(skb);
                                skb->len = 0;
                        }
                }

                /* Copy the data. Returns -EFAULT on error */
                err = memcpy_fromiovec(skb_put(skb,len), msg->msg_iov, len);
                skb->protocol = proto;
                skb->dev = dev;
                skb->priority = sk->sk_priority;
                if (err)
                        goto out_free;

                err = -ENETDOWN;
                if (!(dev->flags & IFF_UP))
                        goto out_free;

                /*
                 *      Now send it
                 */

                dev_queue_xmit(skb);
                dev_put(dev);
                mutex_unlock(&econet_mutex);
                return len;

        out_free:
                kfree_skb(skb);
        out_unlock:
                if (dev)
                        dev_put(dev);
#else
                err = -EPROTOTYPE;
#endif
                mutex_unlock(&econet_mutex);

                return err;
        }

#ifdef CONFIG_ECONET_AUNUDP
        /* AUN virtual Econet. */

        if (udpsock == NULL) {
                mutex_unlock(&econet_mutex);
                return -ENETDOWN;               /* No socket - can't send */
        }

        if (len > 32768) {
                err = -E2BIG;
                goto error;
        }

        /* Make up a UDP datagram and hand it off to some higher intellect. */

        memset(&udpdest, 0, sizeof(udpdest));
        udpdest.sin_family = AF_INET;
        udpdest.sin_port = htons(AUN_PORT);

        /* At the moment we use the stupid Acorn scheme of Econet address
           y.x maps to IP a.b.c.x.  This should be replaced with something
           more flexible and more aware of subnet masks.  */
        {
                struct in_device *idev;
                unsigned long network = 0;

                rcu_read_lock();
                idev = __in_dev_get_rcu(dev);
                if (idev) {
                        if (idev->ifa_list)
                                network = ntohl(idev->ifa_list->ifa_address) &
                                        0xffffff00;             /* !!! */
                }
                rcu_read_unlock();
                udpdest.sin_addr.s_addr = htonl(network | addr.station);
        }

        ah.port = port;
        ah.cb = cb & 0x7f;
        ah.code = 2;            /* magic */
        ah.pad = 0;

        /* tack our header on the front of the iovec */
        size = sizeof(struct aunhdr);
        iov[0].iov_base = (void *)&ah;
        iov[0].iov_len = size;

        userbuf = vmalloc(len);
        if (userbuf == NULL) {
                err = -ENOMEM;
                goto error;
        }

        iov[1].iov_base = userbuf;
        iov[1].iov_len = len;
        err = memcpy_fromiovec(userbuf, msg->msg_iov, len);
        if (err)
                goto error_free_buf;

        /* Get a skbuff (no data, just holds our cb information) */
        if ((skb = sock_alloc_send_skb(sk, 0,
                                       msg->msg_flags & MSG_DONTWAIT,
                                       &err)) == NULL)
                goto error_free_buf;

        eb = (struct ec_cb *)&skb->cb;

        eb->cookie = saddr->cookie;
        eb->timeout = (5*HZ);
        eb->start = jiffies;
        ah.handle = aun_seq;
        eb->seq = (aun_seq++);
        eb->sec = *saddr;

        skb_queue_tail(&aun_queue, skb);

        udpmsg.msg_name = (void *)&udpdest;
        udpmsg.msg_namelen = sizeof(udpdest);
        udpmsg.msg_iov = &iov[0];
        udpmsg.msg_iovlen = 2;
        udpmsg.msg_control = NULL;
        udpmsg.msg_controllen = 0;
        udpmsg.msg_flags=0;

        oldfs = get_fs(); set_fs(KERNEL_DS);    /* More privs :-) */
        err = sock_sendmsg(udpsock, &udpmsg, size);
        set_fs(oldfs);

error_free_buf:
        vfree(userbuf);
error:
#else
        err = -EPROTOTYPE;
#endif
        mutex_unlock(&econet_mutex);

        return err;
}

/*
 *      Look up the address of a socket.
 */

static int econet_getname(struct socket *sock, struct sockaddr *uaddr,
                          int *uaddr_len, int peer)
{
        struct sock *sk;
        struct econet_sock *eo;
        struct sockaddr_ec *sec = (struct sockaddr_ec *)uaddr;

        if (peer)
                return -EOPNOTSUPP;

        memset(sec, 0, sizeof(*sec));
        mutex_lock(&econet_mutex);

        sk = sock->sk;
        eo = ec_sk(sk);

        sec->sec_family   = AF_ECONET;
        sec->port         = eo->port;
        sec->addr.station = eo->station;
        sec->addr.net     = eo->net;

        mutex_unlock(&econet_mutex);

        *uaddr_len = sizeof(*sec);
        return 0;
}

static void econet_destroy_timer(unsigned long data)
{
        struct sock *sk=(struct sock *)data;

        if (!sk_has_allocations(sk)) {
                sk_free(sk);
                return;
        }

        sk->sk_timer.expires = jiffies + 10 * HZ;
        add_timer(&sk->sk_timer);
        printk(KERN_DEBUG "econet socket destroy delayed\n");
}

/*
 *      Close an econet socket.
 */

static int econet_release(struct socket *sock)
{
        struct sock *sk;

        mutex_lock(&econet_mutex);

        sk = sock->sk;
        if (!sk)
                goto out_unlock;

        econet_remove_socket(&econet_sklist, sk);

        /*
         *      Now the socket is dead. No more input will appear.
         */

        sk->sk_state_change(sk);        /* It is useless. Just for sanity. */

        sock_orphan(sk);

        /* Purge queues */

        skb_queue_purge(&sk->sk_receive_queue);

        if (sk_has_allocations(sk)) {
                sk->sk_timer.data     = (unsigned long)sk;
                sk->sk_timer.expires  = jiffies + HZ;
                sk->sk_timer.function = econet_destroy_timer;
                add_timer(&sk->sk_timer);

                goto out_unlock;
        }

        sk_free(sk);

out_unlock:
        mutex_unlock(&econet_mutex);
        return 0;
}

static struct proto econet_proto = {
        .name     = "ECONET",
        .owner    = THIS_MODULE,
        .obj_size = sizeof(struct econet_sock),
};

/*
 *      Create an Econet socket
 */

static int econet_create(struct net *net, struct socket *sock, int protocol,
                         int kern)
{
        struct sock *sk;
        struct econet_sock *eo;
        int err;

        if (!net_eq(net, &init_net))
                return -EAFNOSUPPORT;

        /* Econet only provides datagram services. */
        if (sock->type != SOCK_DGRAM)
                return -ESOCKTNOSUPPORT;

        sock->state = SS_UNCONNECTED;

        err = -ENOBUFS;
        sk = sk_alloc(net, PF_ECONET, GFP_KERNEL, &econet_proto);
        if (sk == NULL)
                goto out;

        sk->sk_reuse = 1;
        sock->ops = &econet_ops;
        sock_init_data(sock, sk);

        eo = ec_sk(sk);
        sock_reset_flag(sk, SOCK_ZAPPED);
        sk->sk_family = PF_ECONET;
        eo->num = protocol;

        econet_insert_socket(&econet_sklist, sk);
        return 0;
out:
        return err;
}

/*
 *      Handle Econet specific ioctls
 */

static int ec_dev_ioctl(struct socket *sock, unsigned int cmd, void __user *arg)
{
        struct ifreq ifr;
        struct ec_device *edev;
        struct net_device *dev;
        struct sockaddr_ec *sec;
        int err;

        /*
         *      Fetch the caller's info block into kernel space
         */

        if (copy_from_user(&ifr, arg, sizeof(struct ifreq)))
                return -EFAULT;

        if ((dev = dev_get_by_name(&init_net, ifr.ifr_name)) == NULL)
                return -ENODEV;

        sec = (struct sockaddr_ec *)&ifr.ifr_addr;

        mutex_lock(&econet_mutex);

        err = 0;
        switch (cmd) {
        case SIOCSIFADDR:
                if (!capable(CAP_NET_ADMIN)) {
                        err = -EPERM;
                        break;
                }

                edev = dev->ec_ptr;
                if (edev == NULL) {
                        /* Magic up a new one. */
                        edev = kzalloc(sizeof(struct ec_device), GFP_KERNEL);
                        if (edev == NULL) {
                                err = -ENOMEM;
                                break;
                        }
                        dev->ec_ptr = edev;
                } else
                        net2dev_map[edev->net] = NULL;
                edev->station = sec->addr.station;
                edev->net = sec->addr.net;
                net2dev_map[sec->addr.net] = dev;
                if (!net2dev_map[0])
                        net2dev_map[0] = dev;
                break;

        case SIOCGIFADDR:
                edev = dev->ec_ptr;
                if (edev == NULL) {
                        err = -ENODEV;
                        break;
                }
                memset(sec, 0, sizeof(struct sockaddr_ec));
                sec->addr.station = edev->station;
                sec->addr.net = edev->net;
                sec->sec_family = AF_ECONET;
                dev_put(dev);
                if (copy_to_user(arg, &ifr, sizeof(struct ifreq)))
                        err = -EFAULT;
                break;

        default:
                err = -EINVAL;
                break;
        }

        mutex_unlock(&econet_mutex);

        dev_put(dev);

        return err;
}

/*
 *      Handle generic ioctls
 */

static int econet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
        struct sock *sk = sock->sk;
        void __user *argp = (void __user *)arg;

        switch(cmd) {
                case SIOCGSTAMP:
                        return sock_get_timestamp(sk, argp);

                case SIOCGSTAMPNS:
                        return sock_get_timestampns(sk, argp);

                case SIOCSIFADDR:
                case SIOCGIFADDR:
                        return ec_dev_ioctl(sock, cmd, argp);
                        break;

                default:
                        return -ENOIOCTLCMD;
        }
        /*NOTREACHED*/
        return 0;
}

static const struct net_proto_family econet_family_ops = {
        .family =       PF_ECONET,
        .create =       econet_create,
        .owner  =       THIS_MODULE,
};

static const struct proto_ops econet_ops = {
        .family =       PF_ECONET,
        .owner =        THIS_MODULE,
        .release =      econet_release,
        .bind =         econet_bind,
        .connect =      sock_no_connect,
        .socketpair =   sock_no_socketpair,
        .accept =       sock_no_accept,
        .getname =      econet_getname,
        .poll =         datagram_poll,
        .ioctl =        econet_ioctl,
        .listen =       sock_no_listen,
        .shutdown =     sock_no_shutdown,
        .setsockopt =   sock_no_setsockopt,
        .getsockopt =   sock_no_getsockopt,
        .sendmsg =      econet_sendmsg,
        .recvmsg =      econet_recvmsg,
        .mmap =         sock_no_mmap,
        .sendpage =     sock_no_sendpage,
};

#if defined(CONFIG_ECONET_AUNUDP) || defined(CONFIG_ECONET_NATIVE)
/*
 *      Find the listening socket, if any, for the given data.
 */

static struct sock *ec_listening_socket(unsigned char port, unsigned char
                                 station, unsigned char net)
{
        struct sock *sk;
        struct hlist_node *node;

        spin_lock(&econet_lock);
        sk_for_each(sk, node, &econet_sklist) {
                struct econet_sock *opt = ec_sk(sk);
                if ((opt->port == port || opt->port == 0) &&
                    (opt->station == station || opt->station == 0) &&
                    (opt->net == net || opt->net == 0)) {
                        sock_hold(sk);
                        goto found;
                }
        }
        sk = NULL;
found:
        spin_unlock(&econet_lock);
        return sk;
}

/*
 *      Queue a received packet for a socket.
 */

static int ec_queue_packet(struct sock *sk, struct sk_buff *skb,
                           unsigned char stn, unsigned char net,
                           unsigned char cb, unsigned char port)
{
        struct ec_cb *eb = (struct ec_cb *)&skb->cb;
        struct sockaddr_ec *sec = (struct sockaddr_ec *)&eb->sec;

        memset(sec, 0, sizeof(struct sockaddr_ec));
        sec->sec_family = AF_ECONET;
        sec->type = ECTYPE_PACKET_RECEIVED;
        sec->port = port;
        sec->cb = cb;
        sec->addr.net = net;
        sec->addr.station = stn;

        return sock_queue_rcv_skb(sk, skb);
}
#endif

#ifdef CONFIG_ECONET_AUNUDP
/*
 *      Send an AUN protocol response.
 */

static void aun_send_response(__u32 addr, unsigned long seq, int code, int cb)
{
        struct sockaddr_in sin = {
                .sin_family = AF_INET,
                .sin_port = htons(AUN_PORT),
                .sin_addr = {.s_addr = addr}
        };
        struct aunhdr ah = {.code = code, .cb = cb, .handle = seq};
        struct kvec iov = {.iov_base = (void *)&ah, .iov_len = sizeof(ah)};
        struct msghdr udpmsg;

        udpmsg.msg_name = (void *)&sin;
        udpmsg.msg_namelen = sizeof(sin);
        udpmsg.msg_control = NULL;
        udpmsg.msg_controllen = 0;
        udpmsg.msg_flags=0;

        kernel_sendmsg(udpsock, &udpmsg, &iov, 1, sizeof(ah));
}


/*
 *      Handle incoming AUN packets.  Work out if anybody wants them,
 *      and send positive or negative acknowledgements as appropriate.
 */

static void aun_incoming(struct sk_buff *skb, struct aunhdr *ah, size_t len)
{
        struct iphdr *ip = ip_hdr(skb);
        unsigned char stn = ntohl(ip->saddr) & 0xff;
        struct dst_entry *dst = skb_dst(skb);
        struct ec_device *edev = NULL;
        struct sock *sk = NULL;
        struct sk_buff *newskb;

        if (dst)
                edev = dst->dev->ec_ptr;

        if (! edev)
                goto bad;

        if ((sk = ec_listening_socket(ah->port, stn, edev->net)) == NULL)
                goto bad;               /* Nobody wants it */

        newskb = alloc_skb((len - sizeof(struct aunhdr) + 15) & ~15,
                           GFP_ATOMIC);
        if (newskb == NULL)
        {
                printk(KERN_DEBUG "AUN: memory squeeze, dropping packet.\n");
                /* Send nack and hope sender tries again */
                goto bad;
        }

        memcpy(skb_put(newskb, len - sizeof(struct aunhdr)), (void *)(ah+1),
               len - sizeof(struct aunhdr));

        if (ec_queue_packet(sk, newskb, stn, edev->net, ah->cb, ah->port))
        {
                /* Socket is bankrupt. */
                kfree_skb(newskb);
                goto bad;
        }

        aun_send_response(ip->saddr, ah->handle, 3, 0);
        sock_put(sk);
        return;

bad:
        aun_send_response(ip->saddr, ah->handle, 4, 0);
        if (sk)
                sock_put(sk);
}

/*
 *      Handle incoming AUN transmit acknowledgements.  If the sequence
 *      number matches something in our backlog then kill it and tell
 *      the user.  If the remote took too long to reply then we may have
 *      dropped the packet already.
 */

static void aun_tx_ack(unsigned long seq, int result)
{
        struct sk_buff *skb;
        unsigned long flags;
        struct ec_cb *eb;

        spin_lock_irqsave(&aun_queue_lock, flags);
        skb_queue_walk(&aun_queue, skb) {
                eb = (struct ec_cb *)&skb->cb;
                if (eb->seq == seq)
                        goto foundit;
        }
        spin_unlock_irqrestore(&aun_queue_lock, flags);
        printk(KERN_DEBUG "AUN: unknown sequence %ld\n", seq);
        return;

foundit:
        tx_result(skb->sk, eb->cookie, result);
        skb_unlink(skb, &aun_queue);
        spin_unlock_irqrestore(&aun_queue_lock, flags);
        kfree_skb(skb);
}

/*
 *      Deal with received AUN frames - sort out what type of thing it is
 *      and hand it to the right function.
 */

static void aun_data_available(struct sock *sk, int slen)
{
        int err;
        struct sk_buff *skb;
        unsigned char *data;
        struct aunhdr *ah;
        struct iphdr *ip;
        size_t len;

        while ((skb = skb_recv_datagram(sk, 0, 1, &err)) == NULL) {
                if (err == -EAGAIN) {
                        printk(KERN_ERR "AUN: no data available?!");
                        return;
                }
                printk(KERN_DEBUG "AUN: recvfrom() error %d\n", -err);
        }

        data = skb_transport_header(skb) + sizeof(struct udphdr);
        ah = (struct aunhdr *)data;
        len = skb->len - sizeof(struct udphdr);
        ip = ip_hdr(skb);

        switch (ah->code)
        {
        case 2:
                aun_incoming(skb, ah, len);
                break;
        case 3:
                aun_tx_ack(ah->handle, ECTYPE_TRANSMIT_OK);
                break;
        case 4:
                aun_tx_ack(ah->handle, ECTYPE_TRANSMIT_NOT_LISTENING);
                break;
#if 0
                /* This isn't quite right yet. */
        case 5:
                aun_send_response(ip->saddr, ah->handle, 6, ah->cb);
                break;
#endif
        default:
                printk(KERN_DEBUG "unknown AUN packet (type %d)\n", data[0]);
        }

        skb_free_datagram(sk, skb);
}

/*
 *      Called by the timer to manage the AUN transmit queue.  If a packet
 *      was sent to a dead or nonexistent host then we will never get an
 *      acknowledgement back.  After a few seconds we need to spot this and
 *      drop the packet.
 */

static void ab_cleanup(unsigned long h)
{
        struct sk_buff *skb, *n;
        unsigned long flags;

        spin_lock_irqsave(&aun_queue_lock, flags);
        skb_queue_walk_safe(&aun_queue, skb, n) {
                struct ec_cb *eb = (struct ec_cb *)&skb->cb;
                if ((jiffies - eb->start) > eb->timeout) {
                        tx_result(skb->sk, eb->cookie,
                                  ECTYPE_TRANSMIT_NOT_PRESENT);
                        skb_unlink(skb, &aun_queue);
                        kfree_skb(skb);
                }
        }
        spin_unlock_irqrestore(&aun_queue_lock, flags);

        mod_timer(&ab_cleanup_timer, jiffies + (HZ*2));
}

static int __init aun_udp_initialise(void)
{
        int error;
        struct sockaddr_in sin;

        skb_queue_head_init(&aun_queue);
        setup_timer(&ab_cleanup_timer, ab_cleanup, 0);
        ab_cleanup_timer.expires = jiffies + (HZ*2);
        add_timer(&ab_cleanup_timer);

        memset(&sin, 0, sizeof(sin));
        sin.sin_port = htons(AUN_PORT);

        /* We can count ourselves lucky Acorn machines are too dim to
           speak IPv6. :-) */
        if ((error = sock_create_kern(PF_INET, SOCK_DGRAM, 0, &udpsock)) < 0)
        {
                printk("AUN: socket error %d\n", -error);
                return error;
        }

        udpsock->sk->sk_reuse = 1;
        udpsock->sk->sk_allocation = GFP_ATOMIC; /* we're going to call it
                                                    from interrupts */

        error = udpsock->ops->bind(udpsock, (struct sockaddr *)&sin,
                                sizeof(sin));
        if (error < 0)
        {
                printk("AUN: bind error %d\n", -error);
                goto release;
        }

        udpsock->sk->sk_data_ready = aun_data_available;

        return 0;

release:
        sock_release(udpsock);
        udpsock = NULL;
        return error;
}
#endif

#ifdef CONFIG_ECONET_NATIVE

/*
 *      Receive an Econet frame from a device.
 */

static int econet_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt, struct net_device *orig_dev)
{
        struct ec_framehdr *hdr;
        struct sock *sk = NULL;
        struct ec_device *edev = dev->ec_ptr;

        if (!net_eq(dev_net(dev), &init_net))
                goto drop;

        if (skb->pkt_type == PACKET_OTHERHOST)
                goto drop;

        if (!edev)
                goto drop;

        if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL)
                return NET_RX_DROP;

        if (!pskb_may_pull(skb, sizeof(struct ec_framehdr)))
                goto drop;

        hdr = (struct ec_framehdr *) skb->data;

        /* First check for encapsulated IP */
        if (hdr->port == EC_PORT_IP) {
                skb->protocol = htons(ETH_P_IP);
                skb_pull(skb, sizeof(struct ec_framehdr));
                netif_rx(skb);
                return NET_RX_SUCCESS;
        }

        sk = ec_listening_socket(hdr->port, hdr->src_stn, hdr->src_net);
        if (!sk)
                goto drop;

        if (ec_queue_packet(sk, skb, edev->net, hdr->src_stn, hdr->cb,
                            hdr->port))
                goto drop;
        sock_put(sk);
        return NET_RX_SUCCESS;

drop:
        if (sk)
                sock_put(sk);
        kfree_skb(skb);
        return NET_RX_DROP;
}

static struct packet_type econet_packet_type __read_mostly = {
        .type =         cpu_to_be16(ETH_P_ECONET),
        .func =         econet_rcv,
};

static void econet_hw_initialise(void)
{
        dev_add_pack(&econet_packet_type);
}

#endif

static int econet_notifier(struct notifier_block *this, unsigned long msg, void *data)
{
        struct net_device *dev = (struct net_device *)data;
        struct ec_device *edev;

        if (!net_eq(dev_net(dev), &init_net))
                return NOTIFY_DONE;

        switch (msg) {
        case NETDEV_UNREGISTER:
                /* A device has gone down - kill any data we hold for it. */
                edev = dev->ec_ptr;
                if (edev)
                {
                        if (net2dev_map[0] == dev)
                                net2dev_map[0] = NULL;
                        net2dev_map[edev->net] = NULL;
                        kfree(edev);
                        dev->ec_ptr = NULL;
                }
                break;
        }

        return NOTIFY_DONE;
}

static struct notifier_block econet_netdev_notifier = {
        .notifier_call =econet_notifier,
};

static void __exit econet_proto_exit(void)
{
#ifdef CONFIG_ECONET_AUNUDP
        del_timer(&ab_cleanup_timer);
        if (udpsock)
                sock_release(udpsock);
#endif
        unregister_netdevice_notifier(&econet_netdev_notifier);
#ifdef CONFIG_ECONET_NATIVE
        dev_remove_pack(&econet_packet_type);
#endif
        sock_unregister(econet_family_ops.family);
        proto_unregister(&econet_proto);
}

static int __init econet_proto_init(void)
{
        int err = proto_register(&econet_proto, 0);

        if (err != 0)
                goto out;
        sock_register(&econet_family_ops);
#ifdef CONFIG_ECONET_AUNUDP
        aun_udp_initialise();
#endif
#ifdef CONFIG_ECONET_NATIVE
        econet_hw_initialise();
#endif
        register_netdevice_notifier(&econet_netdev_notifier);
out:
        return err;
}

module_init(econet_proto_init);
module_exit(econet_proto_exit);

MODULE_LICENSE("GPL");
MODULE_ALIAS_NETPROTO(PF_ECONET);