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af_econet.c

/*
 *    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 <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_RWLOCK(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)
{
      write_lock_bh(&econet_lock);
      sk_del_node_init(sk);
      write_unlock_bh(&econet_lock);
}

static void econet_insert_socket(struct hlist_head *list, struct sock *sk)
{
      write_lock_bh(&econet_lock);
      sk_add_node(sk, list);
      write_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 sock *sk = sock->sk;
      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 sk_buff *skb;
      struct ec_cb *eb;
#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|MSG_CMSG_COMPAT))
            return -EINVAL;

      /*
       *    Get and verify the address.
       */

      mutex_lock(&econet_mutex);

      if (saddr == NULL) {
            struct econet_sock *eo = ec_sk(sk);

            addr.station = eo->station;
            addr.net     = eo->net;
            port       = eo->port;
            cb         = eo->cb;
      } else {
            if (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 (len + 15 > dev->mtu) {
            mutex_unlock(&econet_mutex);
            return -EMSGSIZE;
      }

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

            dev_hold(dev);

            skb = sock_alloc_send_skb(sk, len+LL_RESERVED_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;

            /* BUG: saddr may be NULL */
            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 */
      }

      /* 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);
      /*
       * XXX: that is b0rken.  We can't mix userland and kernel pointers
       * in iovec, since on a lot of platforms copy_from_user() will
       * *not* work with the kernel and userland ones at the same time,
       * regardless of what we do with set_fs().  And we are talking about
       * econet-over-ethernet here, so "it's only ARM anyway" doesn't
       * apply.  Any suggestions on fixing that code?       -- AV
       */
      iov[0].iov_base = (void *)&ah;
      iov[0].iov_len = size;
      for (i = 0; i < msg->msg_iovlen; i++) {
            void __user *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 (!access_ok(VERIFY_READ, base, len)) {
                  mutex_unlock(&econet_mutex);
                  return -EFAULT;
            }
            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,
                               msg->msg_flags & MSG_DONTWAIT,
                               &err)) == NULL) {
            mutex_unlock(&econet_mutex);
            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
      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;

      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 (!atomic_read(&sk->sk_wmem_alloc) &&
          !atomic_read(&sk->sk_rmem_alloc)) {
            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->sk = NULL;
      sk->sk_socket = NULL;
      sock_set_flag(sk, SOCK_DEAD);

      /* Purge queues */

      skb_queue_purge(&sk->sk_receive_queue);

      if (atomic_read(&sk->sk_rmem_alloc) ||
          atomic_read(&sk->sk_wmem_alloc)) {
            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)
{
      struct sock *sk;
      struct econet_sock *eo;
      int err;

      if (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:
            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 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;

      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))
                  goto found;
      }
      sk = NULL;
found:
      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 sock *sk;
      struct sk_buff *newskb;
      struct ec_device *edev = skb->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);
      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, &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;
      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, &aun_queue);
                  kfree_skb(skb);
            }
            skb = newskb;
      }
      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);
      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_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;
      struct ec_device *edev = dev->ec_ptr;

      if (dev->nd_net != &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 0;
      }

      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;

      return 0;

drop:
      kfree_skb(skb);
      return NET_RX_DROP;
}

static struct packet_type econet_packet_type = {
      .type =           __constant_htons(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 (dev->nd_net != &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
      spin_lock_init(&aun_queue_lock);
      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);

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