econet.c

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/*
 *      An implementation of the Acorn Econet and AUN protocols.
 *      Philip Blundell <philb@gnu.org>
 *
 *      Fixes:
 *
 *      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/config.h>
#include <linux/module.h>

#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/bitops.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.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 <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 <asm/spinlock.h>

static struct proto_ops econet_ops;
static struct sock *econet_sklist;

static spinlock_t aun_queue_lock;

#ifdef CONFIG_ECONET_AUNUDP
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 = 0;

/* 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
};

struct ec_device
{
        struct device *dev;             /* Real device structure */
        unsigned char station, net;     /* Econet protocol address */
        struct ec_device *prev, *next;  /* Linked list */
};

static struct ec_device *edevlist = NULL;

static spinlock_t edevlist_lock;

/*
 *      Faster version of edev_get - call with IRQs off
 */

static __inline__ struct ec_device *__edev_get(struct device *dev)
{
        struct ec_device *edev;
        for (edev = edevlist; edev; edev = edev->next)
        {
                if (edev->dev == dev)
                        break;
        }
        return edev;
}

/*
 *      Find an Econet device given its `dev' pointer.  This is IRQ safe.
 */

static struct ec_device *edev_get(struct device *dev)
{
        struct ec_device *edev;
        unsigned long flags;
        spin_lock_irqsave(&edevlist_lock, flags);
        edev = __edev_get(dev);
        spin_unlock_irqrestore(&edevlist_lock, flags);
        return edev;
}

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

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

        msg->msg_namelen = sizeof(struct sockaddr_ec);

        /*
         *      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->stamp=skb->stamp;

        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:
        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=sock->sk;
        
        /*
         *      Check legality
         */
         
        if (addr_len < sizeof(struct sockaddr_ec))
                return -EINVAL;
        if (sec->sec_family != AF_ECONET)
                return -EINVAL;
        
        sk->protinfo.af_econet->cb = sec->cb;
        sk->protinfo.af_econet->port = sec->port;
        sk->protinfo.af_econet->station = sec->addr.station;
        sk->protinfo.af_econet->net = sec->addr.net;

        return 0;
}

/*
 *      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);
}

#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 socket *sock, struct msghdr *msg, int len,
                          struct scm_cookie *scm)
{
        struct sock *sk = sock->sk;
        struct sockaddr_ec *saddr=(struct sockaddr_ec *)msg->msg_name;
        struct device *dev;
        struct ec_addr addr;
        struct ec_device *edev;
        int err;
        unsigned char port, cb;
        struct sk_buff *skb;
        struct ec_cb *eb;
#ifdef CONFIG_ECONET_NATIVE
        unsigned short proto = 0;
#endif
#ifdef CONFIG_ECONET_AUNUDP
        struct msghdr udpmsg;
        struct iovec iov[msg->msg_iovlen+1];
        struct aunhdr ah;
        struct sockaddr_in udpdest;
        __kernel_size_t size;
        int i;
        mm_segment_t oldfs;
#endif
                
        /*
         *      Check the flags. 
         */

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

        /*
         *      Get and verify the address. 
         */
         
        if (saddr == NULL) {
                addr.station = sk->protinfo.af_econet->station;
                addr.net = sk->protinfo.af_econet->net;
                port = sk->protinfo.af_econet->port;
                cb = sk->protinfo.af_econet->cb;
        } else {
                if (msg->msg_namelen < sizeof(struct sockaddr_ec)) 
                        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. */
        for (edev = edevlist; edev && (edev->net != addr.net); 
             edev = edev->next);

        /* Bridge?  What's that? */
        if (edev == NULL) 
                return -ENETUNREACH;

        dev = edev->dev;

        if (dev->type == ARPHRD_ECONET)
        {
                /* Real hardware Econet.  We're not worthy etc. */
#ifdef CONFIG_ECONET_NATIVE
                dev_lock_list();
                
                skb = sock_alloc_send_skb(sk, len+dev->hard_header_len+15, 0, 
                                          msg->msg_flags & MSG_DONTWAIT, &err);
                if (skb==NULL)
                        goto out_unlock;
                
                skb_reserve(skb, (dev->hard_header_len+15)&~15);
                skb->nh.raw = skb->data;
                
                eb = (struct ec_cb *)&skb->cb;
                
                eb->cookie = saddr->cookie;
                eb->sec = *saddr;
                eb->sent = ec_tx_done;

                if (dev->hard_header) {
                        int res;
                        err = -EINVAL;
                        res = dev->hard_header(skb, dev, ntohs(proto), &addr, NULL, len);
                        if (sock->type != SOCK_DGRAM) {
                                skb->tail = skb->data;
                                skb->len = 0;
                        } else if (res < 0)
                                goto out_free;
                }
                
                /* 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->priority;
                if (err)
                        goto out_free;
                
                err = -ENETDOWN;
                if (!(dev->flags & IFF_UP))
                        goto out_free;
                
                /*
                 *      Now send it
                 */
                
                dev_unlock_list();
                dev_queue_xmit(skb);
                return(len);

        out_free:
                kfree_skb(skb);
        out_unlock:
                dev_unlock_list();
#else
                err = -EPROTOTYPE;
#endif
                return err;
        }

#ifdef CONFIG_ECONET_AUNUDP
        /* AUN virtual Econet. */

        if (udpsock == NULL)
                return -ENETDOWN;               /* No socket - can't send */
        
        /* 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 = (struct in_device *)dev->ip_ptr;
                unsigned long network = ntohl(idev->ifa_list->ifa_address) & 
                        0xffffff00;             /* !!! */
                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;
        for (i = 0; i < msg->msg_iovlen; i++) {
                void *base = msg->msg_iov[i].iov_base;
                size_t len = msg->msg_iov[i].iov_len;
                /* Check it now since we switch to KERNEL_DS later. */
                if ((err = verify_area(VERIFY_READ, base, len)) < 0)
                        return err;
                iov[i+1].iov_base = base;
                iov[i+1].iov_len = len;
                size += len;
        }

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

        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 = msg->msg_iovlen + 1;
        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);
#else
        err = -EPROTOTYPE;
#endif
        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 = sock->sk;
        struct sockaddr_ec *sec = (struct sockaddr_ec *)uaddr;

        if (peer)
                return -EOPNOTSUPP;

        sec->sec_family = AF_ECONET;
        sec->port = sk->protinfo.af_econet->port;
        sec->addr.station = sk->protinfo.af_econet->station;
        sec->addr.net = sk->protinfo.af_econet->net;

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

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

        if (!atomic_read(&sk->wmem_alloc) && !atomic_read(&sk->rmem_alloc)) {
                sk_free(sk);
                MOD_DEC_USE_COUNT;
                return;
        }

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

/*
 *      Close an econet socket.
 */

static int econet_release(struct socket *sock, struct socket *peersock)
{
        struct sk_buff  *skb;
        struct sock *sk = sock->sk;

        if (!sk)
                return 0;

        sklist_remove_socket(&econet_sklist, sk);

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

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

        sock->sk = NULL;
        sk->socket = NULL;
        sk->dead = 1;

        /* Purge queues */

        while ((skb=skb_dequeue(&sk->receive_queue))!=NULL)
                kfree_skb(skb);

        if (atomic_read(&sk->rmem_alloc) || atomic_read(&sk->wmem_alloc)) {
                sk->timer.data=(unsigned long)sk;
                sk->timer.expires=jiffies+HZ;
                sk->timer.function=econet_destroy_timer;
                add_timer(&sk->timer);
                return 0;
        }

        sk_free(sk);
        MOD_DEC_USE_COUNT;
        return 0;
}

/*
 *      Create an Econet socket
 */

static int econet_create(struct socket *sock, int protocol)
{
        struct sock *sk;
        int err;

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

        sock->state = SS_UNCONNECTED;
        MOD_INC_USE_COUNT;

        err = -ENOBUFS;
        sk = sk_alloc(PF_ECONET, GFP_KERNEL, 1);
        if (sk == NULL)
                goto out;

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

        sk->protinfo.af_econet = kmalloc(sizeof(struct econet_opt), GFP_KERNEL);
        if (sk->protinfo.af_econet == NULL)
                goto out_free;
        memset(sk->protinfo.af_econet, 0, sizeof(struct econet_opt));
        sk->zapped=0;
        sk->family = PF_ECONET;
        sk->num = protocol;

        sklist_insert_socket(&econet_sklist, sk);
        return(0);

out_free:
        sk_free(sk);
out:
        MOD_DEC_USE_COUNT;
        return err;
}

/*
 *      Handle Econet specific ioctls
 */

static int ec_dev_ioctl(struct socket *sock, unsigned int cmd, void *arg)
{
        struct ifreq ifr;
        struct ec_device *edev;
        struct device *dev;
        unsigned long flags;
        struct sockaddr_ec *sec;

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

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

        if ((dev = dev_get(ifr.ifr_name)) == NULL) 
                return -ENODEV;

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

        switch (cmd)
        {
        case SIOCSIFADDR:
                spin_lock_irqsave(&edevlist_lock, flags);
                edev = __edev_get(dev);
                if (edev == NULL)
                {
                        /* Magic up a new one. */
                        edev = kmalloc(GFP_KERNEL, sizeof(struct ec_device));
                        if (edev == NULL) {
                                printk("af_ec: memory squeeze.\n");
                                spin_unlock_irqrestore(&edevlist_lock, flags);
                                return -ENOMEM;
                        }
                        memset(edev, 0, sizeof(struct ec_device));
                        edev->dev = dev;
                        edev->next = edevlist;
                        edevlist = edev;
                }
                edev->station = sec->addr.station;
                edev->net = sec->addr.net;
                spin_unlock_irqrestore(&edevlist_lock, flags);
                return 0;

        case SIOCGIFADDR:
                spin_lock_irqsave(&edevlist_lock, flags);
                edev = __edev_get(dev);
                if (edev == NULL)
                {
                        spin_unlock_irqrestore(&edevlist_lock, flags);
                        return -ENODEV;
                }
                memset(sec, 0, sizeof(struct sockaddr_ec));
                sec->addr.station = edev->station;
                sec->addr.net = edev->net;
                sec->sec_family = AF_ECONET;
                spin_unlock_irqrestore(&edevlist_lock, flags);
                if (copy_to_user(arg, &ifr, sizeof(struct ifreq)))
                        return -EFAULT;
                return 0;
        }

        return -EINVAL;
}

/*
 *      Handle generic ioctls
 */

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

        switch(cmd) 
        {
                case FIOSETOWN:
                case SIOCSPGRP:
                        err = get_user(pid, (int *) arg);
                        if (err)
                                return err; 
                        if (current->pid != pid && current->pgrp != -pid && !suser())
                                return -EPERM;
                        sk->proc = pid;
                        return(0);
                case FIOGETOWN:
                case SIOCGPGRP:
                        return put_user(sk->proc, (int *)arg);
                case SIOCGSTAMP:
                        if(sk->stamp.tv_sec==0)
                                return -ENOENT;
                        err = -EFAULT;
                        if (!copy_to_user((void *)arg, &sk->stamp, sizeof(struct timeval)))
                                err = 0;
                        return err;
                case SIOCGIFFLAGS:
                case SIOCSIFFLAGS:
                case SIOCGIFCONF:
                case SIOCGIFMETRIC:
                case SIOCSIFMETRIC:
                case SIOCGIFMEM:
                case SIOCSIFMEM:
                case SIOCGIFMTU:
                case SIOCSIFMTU:
                case SIOCSIFLINK:
                case SIOCGIFHWADDR:
                case SIOCSIFHWADDR:
                case SIOCSIFMAP:
                case SIOCGIFMAP:
                case SIOCSIFSLAVE:
                case SIOCGIFSLAVE:
                case SIOCGIFINDEX:
                case SIOCGIFNAME:
                case SIOCGIFCOUNT:
                case SIOCSIFHWBROADCAST:
                        return(dev_ioctl(cmd,(void *) arg));

                case SIOCSIFADDR:
                case SIOCGIFADDR:
                        return ec_dev_ioctl(sock, cmd, (void *)arg);
                        break;

                default:
                        return(dev_ioctl(cmd,(void *) arg));
        }
        /*NOTREACHED*/
        return 0;
}

static struct net_proto_family econet_family_ops = {
        PF_ECONET,
        econet_create
};

static struct proto_ops econet_ops = {
        PF_ECONET,

        sock_no_dup,
        econet_release,
        econet_bind,
        sock_no_connect,
        sock_no_socketpair,
        sock_no_accept,
        econet_getname, 
        datagram_poll,
        econet_ioctl,
        sock_no_listen,
        sock_no_shutdown,
        sock_no_setsockopt,
        sock_no_getsockopt,
        sock_no_fcntl,
        econet_sendmsg,
        econet_recvmsg
};

/*
 *      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 = econet_sklist;

        while (sk)
        {
                struct econet_opt *opt = sk->protinfo.af_econet;
                if ((opt->port == port || opt->port == 0) && 
                    (opt->station == station || opt->station == 0) &&
                    (opt->net == net || opt->net == 0))
                        return sk;
                sk = sk->sklist_next;
        }

        return NULL;
}

#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;
        struct iovec iov;
        struct aunhdr ah;
        struct msghdr udpmsg;
        int err;
        mm_segment_t oldfs;
        
        memset(&sin, 0, sizeof(sin));
        sin.sin_family = AF_INET;
        sin.sin_port = htons(AUN_PORT);
        sin.sin_addr.s_addr = addr;

        ah.code = code;
        ah.pad = 0;
        ah.port = 0;
        ah.cb = cb;
        ah.handle = seq;

        iov.iov_base = (void *)&ah;
        iov.iov_len = sizeof(ah);

        udpmsg.msg_name = (void *)&sin;
        udpmsg.msg_namelen = sizeof(sin);
        udpmsg.msg_iov = &iov;
        udpmsg.msg_iovlen = 1;
        udpmsg.msg_control = NULL;
        udpmsg.msg_controllen = 0;
        udpmsg.msg_flags=0;

        oldfs = get_fs(); set_fs(KERNEL_DS);
        err = sock_sendmsg(udpsock, &udpmsg, sizeof(ah));
        set_fs(oldfs);
}

/*
 *      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 ec_device *edev = edev_get(skb->dev);
        struct iphdr *ip = skb->nh.iph;
        unsigned char stn = ntohl(ip->saddr) & 0xff;
        struct sock *sk;
        struct sk_buff *newskb;
        struct ec_cb *eb;
        struct sockaddr_ec *sec;

        if (edev == NULL)
                return;         /* Device not configured for AUN */
        
        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;
        }

        eb = (struct ec_cb *)&newskb->cb;
        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 = ah->port;
        sec->cb = ah->cb;
        sec->addr.net = edev->net;
        sec->addr.station = stn;

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

        if (sock_queue_rcv_skb(sk, newskb) < 0)
        {
                /* Socket is bankrupt. */
                kfree_skb(newskb);
                goto bad;
        }

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

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

/*
 *      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 = skb_peek(&aun_queue);
        while (skb && skb != (struct sk_buff *)&aun_queue)
        {
                struct sk_buff *newskb = skb->next;
                eb = (struct ec_cb *)&skb->cb;
                if (eb->seq == seq)
                        goto foundit;

                skb = newskb;
        }
        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);
        spin_unlock_irqrestore(&aun_queue_lock, flags);
}

/*
 *      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->h.raw + sizeof(struct udphdr);
        ah = (struct aunhdr *)data;
        len = skb->len - sizeof(struct udphdr);
        ip = skb->nh.iph;

        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;
        unsigned long flags;

        spin_lock_irqsave(&aun_queue_lock, flags);
        skb = skb_peek(&aun_queue);
        while (skb && skb != (struct sk_buff *)&aun_queue)
        {
                struct sk_buff *newskb = skb->next;
                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);
                }
                skb = newskb;
        }
        spin_unlock_irqrestore(&aun_queue_lock, flags);

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

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

        skb_queue_head_init(&aun_queue);
        spin_lock_init(&aun_queue_lock);
        init_timer(&ab_cleanup_timer);
        ab_cleanup_timer.expires = jiffies + (HZ*2);
        ab_cleanup_timer.function = ab_cleanup;
        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(PF_INET, SOCK_DGRAM, 0, &udpsock)) < 0)
        {
                printk("AUN: socket error %d\n", -error);
                return error;
        }
        
        udpsock->sk->reuse = 1;
        udpsock->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->data_ready = aun_data_available;

        return 0;

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

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

        switch (msg) {
        case NETDEV_UNREGISTER:
                /* A device has gone down - kill any data we hold for it. */
                spin_lock_irqsave(&edevlist_lock, flags);
                for (edev = edevlist; edev; edev = edev->next)
                {
                        if (edev->dev == dev)
                        {
                                if (edev->prev)
                                        edev->prev->next = edev->next;
                                else
                                        edevlist = edev->next;
                                if (edev->next)
                                        edev->next->prev = edev->prev;
                                kfree(edev);
                                break;
                        }
                }
                spin_unlock_irqrestore(&edevlist_lock, flags);
                break;
        }

        return NOTIFY_DONE;
}

struct notifier_block econet_netdev_notifier={
        econet_notifier,
        NULL,
        0
};

#ifdef MODULE
void cleanup_module(void)
{
#ifdef CONFIG_ECONET_AUNUDP
        del_timer(&ab_cleanup_timer);
        if (udpsock)
                sock_release(udpsock);
#endif
        unregister_netdevice_notifier(&econet_netdev_notifier);
        sock_unregister(econet_family_ops.family);
        return;
}

int init_module(void)
#else
__initfunc(void econet_proto_init(struct net_proto *pro))
#endif
{
        spin_lock_init(&edevlist_lock);
        spin_lock_init(&aun_queue_lock);
        /* Stop warnings from happening on UP systems. */
        (void)edevlist_lock;
        (void)aun_queue_lock;
        sock_register(&econet_family_ops);
#ifdef CONFIG_ECONET_AUNUDP
        aun_udp_initialise();
#endif
        register_netdevice_notifier(&econet_netdev_notifier);
#ifdef MODULE
        return 0;
#endif
}

---