ClabureDB: Classified Bug-Reports Database

   /*
    *        AARP:                An implementation of the AppleTalk AARP protocol for
    *                        Ethernet 'ELAP'.
    *
    *                Alan Cox  <Alan.Cox@linux.org>
    *
    *        This doesn't fit cleanly with the IP arp. Potentially we can use
    *        the generic neighbour discovery code to clean this up.
    *
   *        FIXME:
   *                We ought to handle the retransmits with a single list and a
   *        separate fast timer for when it is needed.
   *                Use neighbour discovery code.
   *                Token Ring Support.
   *
   *                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.
   *
   *
   *        References:
   *                Inside AppleTalk (2nd Ed).
   *        Fixes:
   *                Jaume Grau        -        flush caches on AARP_PROBE
   *                Rob Newberry        -        Added proxy AARP and AARP proc fs,
   *                                        moved probing from DDP module.
   *                Arnaldo C. Melo -        don't mangle rx packets
   *
   */
  
  #include <linux/if_arp.h>
  #include <net/sock.h>
  #include <net/datalink.h>
  #include <net/psnap.h>
  #include <linux/atalk.h>
  #include <linux/delay.h>
  #include <linux/init.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  
  int sysctl_aarp_expiry_time = AARP_EXPIRY_TIME;
  int sysctl_aarp_tick_time = AARP_TICK_TIME;
  int sysctl_aarp_retransmit_limit = AARP_RETRANSMIT_LIMIT;
  int sysctl_aarp_resolve_time = AARP_RESOLVE_TIME;
  
  /* Lists of aarp entries */
  /**
   *        struct aarp_entry - AARP entry
   *        @last_sent - Last time we xmitted the aarp request
   *        @packet_queue - Queue of frames wait for resolution
   *        @status - Used for proxy AARP
   *        expires_at - Entry expiry time
   *        target_addr - DDP Address
   *        dev - Device to use
   *        hwaddr - Physical i/f address of target/router
   *        xmit_count - When this hits 10 we give up
   *        next - Next entry in chain
   */
  struct aarp_entry {
          /* These first two are only used for unresolved entries */
          unsigned long                last_sent;
          struct sk_buff_head        packet_queue;
          int                        status;
          unsigned long                expires_at;
          struct atalk_addr        target_addr;
          struct net_device        *dev;
          char                        hwaddr[6];
          unsigned short                xmit_count;
          struct aarp_entry        *next;
  };
  
  /* Hashed list of resolved, unresolved and proxy entries */
  static struct aarp_entry *resolved[AARP_HASH_SIZE];
  static struct aarp_entry *unresolved[AARP_HASH_SIZE];
  static struct aarp_entry *proxies[AARP_HASH_SIZE];
  static int unresolved_count;
  
  /* One lock protects it all. */
  static DEFINE_RWLOCK(aarp_lock);
  
  /* Used to walk the list and purge/kick entries.  */
  static struct timer_list aarp_timer;
  
  /*
   *        Delete an aarp queue
   *
   *        Must run under aarp_lock.
   */
  static void __aarp_expire(struct aarp_entry *a)
  {
          skb_queue_purge(&a->packet_queue);
          kfree(a);
  }
  
  /*
   *        Send an aarp queue entry request
   *
   *        Must run under aarp_lock.
  */
 static void __aarp_send_query(struct aarp_entry *a)
 {
         static unsigned char aarp_eth_multicast[ETH_ALEN] =
                                         { 0x09, 0x00, 0x07, 0xFF, 0xFF, 0xFF };
         struct net_device *dev = a->dev;
         struct elapaarp *eah;
         int len = dev->hard_header_len + sizeof(*eah) + aarp_dl->header_length;
         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
         struct atalk_addr *sat = atalk_find_dev_addr(dev);
 
         if (!skb)
                 return;
 
         if (!sat) {
                 kfree_skb(skb);
                 return;
         }
 
         /* Set up the buffer */
         skb_reserve(skb, dev->hard_header_len + aarp_dl->header_length);
         skb_reset_network_header(skb);
         skb_reset_transport_header(skb);
         skb_put(skb, sizeof(*eah));
         skb->protocol    = htons(ETH_P_ATALK);
         skb->dev         = dev;
         eah                 = aarp_hdr(skb);
 
         /* Set up the ARP */
         eah->hw_type         = htons(AARP_HW_TYPE_ETHERNET);
         eah->pa_type         = htons(ETH_P_ATALK);
         eah->hw_len         = ETH_ALEN;
         eah->pa_len         = AARP_PA_ALEN;
         eah->function         = htons(AARP_REQUEST);
 
         memcpy(eah->hw_src, dev->dev_addr, ETH_ALEN);
 
         eah->pa_src_zero = 0;
         eah->pa_src_net         = sat->s_net;
         eah->pa_src_node = sat->s_node;
 
         memset(eah->hw_dst, '\0', ETH_ALEN);
 
         eah->pa_dst_zero = 0;
         eah->pa_dst_net         = a->target_addr.s_net;
         eah->pa_dst_node = a->target_addr.s_node;
 
         /* Send it */
         aarp_dl->request(aarp_dl, skb, aarp_eth_multicast);
         /* Update the sending count */
         a->xmit_count++;
         a->last_sent = jiffies;
 }
 
 /* This runs under aarp_lock and in softint context, so only atomic memory
  * allocations can be used. */
 static void aarp_send_reply(struct net_device *dev, struct atalk_addr *us,
                             struct atalk_addr *them, unsigned char *sha)
 {
         struct elapaarp *eah;
         int len = dev->hard_header_len + sizeof(*eah) + aarp_dl->header_length;
         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 
         if (!skb)
                 return;
 
         /* Set up the buffer */
         skb_reserve(skb, dev->hard_header_len + aarp_dl->header_length);
         skb_reset_network_header(skb);
         skb_reset_transport_header(skb);
         skb_put(skb, sizeof(*eah));
         skb->protocol    = htons(ETH_P_ATALK);
         skb->dev         = dev;
         eah                 = aarp_hdr(skb);
 
         /* Set up the ARP */
         eah->hw_type         = htons(AARP_HW_TYPE_ETHERNET);
         eah->pa_type         = htons(ETH_P_ATALK);
         eah->hw_len         = ETH_ALEN;
         eah->pa_len         = AARP_PA_ALEN;
         eah->function         = htons(AARP_REPLY);
 
         memcpy(eah->hw_src, dev->dev_addr, ETH_ALEN);
 
         eah->pa_src_zero = 0;
         eah->pa_src_net         = us->s_net;
         eah->pa_src_node = us->s_node;
 
         if (!sha)
                 memset(eah->hw_dst, '\0', ETH_ALEN);
         else
                 memcpy(eah->hw_dst, sha, ETH_ALEN);
 
         eah->pa_dst_zero = 0;
         eah->pa_dst_net         = them->s_net;
         eah->pa_dst_node = them->s_node;
 
         /* Send it */
         aarp_dl->request(aarp_dl, skb, sha);
 }
 
 /*
  *        Send probe frames. Called from aarp_probe_network and
  *        aarp_proxy_probe_network.
  */
 
 static void aarp_send_probe(struct net_device *dev, struct atalk_addr *us)
 {
         struct elapaarp *eah;
         int len = dev->hard_header_len + sizeof(*eah) + aarp_dl->header_length;
         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
         static unsigned char aarp_eth_multicast[ETH_ALEN] =
                                         { 0x09, 0x00, 0x07, 0xFF, 0xFF, 0xFF };
 
         if (!skb)
                 return;
 
         /* Set up the buffer */
         skb_reserve(skb, dev->hard_header_len + aarp_dl->header_length);
         skb_reset_network_header(skb);
         skb_reset_transport_header(skb);
         skb_put(skb, sizeof(*eah));
         skb->protocol    = htons(ETH_P_ATALK);
         skb->dev         = dev;
         eah                 = aarp_hdr(skb);
 
         /* Set up the ARP */
         eah->hw_type         = htons(AARP_HW_TYPE_ETHERNET);
         eah->pa_type         = htons(ETH_P_ATALK);
         eah->hw_len         = ETH_ALEN;
         eah->pa_len         = AARP_PA_ALEN;
         eah->function         = htons(AARP_PROBE);
 
         memcpy(eah->hw_src, dev->dev_addr, ETH_ALEN);
 
         eah->pa_src_zero = 0;
         eah->pa_src_net         = us->s_net;
         eah->pa_src_node = us->s_node;
 
         memset(eah->hw_dst, '\0', ETH_ALEN);
 
         eah->pa_dst_zero = 0;
         eah->pa_dst_net         = us->s_net;
         eah->pa_dst_node = us->s_node;
 
         /* Send it */
         aarp_dl->request(aarp_dl, skb, aarp_eth_multicast);
 }
 
 /*
  *        Handle an aarp timer expire
  *
  *        Must run under the aarp_lock.
  */
 
 static void __aarp_expire_timer(struct aarp_entry **n)
 {
         struct aarp_entry *t;
 
         while (*n)
                 /* Expired ? */
                 if (time_after(jiffies, (*n)->expires_at)) {
                         t = *n;
                         *n = (*n)->next;
                         __aarp_expire(t);
                 } else
                         n = &((*n)->next);
 }
 
 /*
  *        Kick all pending requests 5 times a second.
  *
  *        Must run under the aarp_lock.
  */
 static void __aarp_kick(struct aarp_entry **n)
 {
         struct aarp_entry *t;
 
         while (*n)
                 /* Expired: if this will be the 11th tx, we delete instead. */
                 if ((*n)->xmit_count >= sysctl_aarp_retransmit_limit) {
                         t = *n;
                         *n = (*n)->next;
                         __aarp_expire(t);
                 } else {
                         __aarp_send_query(*n);
                         n = &((*n)->next);
                 }
 }
 
 /*
  *        A device has gone down. Take all entries referring to the device
  *        and remove them.
  *
  *        Must run under the aarp_lock.
  */
 static void __aarp_expire_device(struct aarp_entry **n, struct net_device *dev)
 {
         struct aarp_entry *t;
 
         while (*n)
                 if ((*n)->dev == dev) {
                         t = *n;
                         *n = (*n)->next;
                         __aarp_expire(t);
                 } else
                         n = &((*n)->next);
 }
 
 /* Handle the timer event */
 static void aarp_expire_timeout(unsigned long unused)
 {
         int ct;
 
         write_lock_bh(&aarp_lock);
 
         for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
                 __aarp_expire_timer(&resolved[ct]);
                 __aarp_kick(&unresolved[ct]);
                 __aarp_expire_timer(&unresolved[ct]);
                 __aarp_expire_timer(&proxies[ct]);
         }
 
         write_unlock_bh(&aarp_lock);
         mod_timer(&aarp_timer, jiffies +
                                (unresolved_count ? sysctl_aarp_tick_time :
                                 sysctl_aarp_expiry_time));
 }
 
 /* Network device notifier chain handler. */
 static int aarp_device_event(struct notifier_block *this, unsigned long event,
                              void *ptr)
 {
         struct net_device *dev = ptr;
         int ct;
 
         if (!net_eq(dev_net(dev), &init_net))
                 return NOTIFY_DONE;
 
         if (event == NETDEV_DOWN) {
                 write_lock_bh(&aarp_lock);
 
                 for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
                         __aarp_expire_device(&resolved[ct], dev);
                         __aarp_expire_device(&unresolved[ct], dev);
                         __aarp_expire_device(&proxies[ct], dev);
                 }
 
                 write_unlock_bh(&aarp_lock);
         }
         return NOTIFY_DONE;
 }
 
 /* Expire all entries in a hash chain */
 static void __aarp_expire_all(struct aarp_entry **n)
 {
         struct aarp_entry *t;
 
         while (*n) {
                 t = *n;
                 *n = (*n)->next;
                 __aarp_expire(t);
         }
 }
 
 /* Cleanup all hash chains -- module unloading */
 static void aarp_purge(void)
 {
         int ct;
 
         write_lock_bh(&aarp_lock);
         for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
                 __aarp_expire_all(&resolved[ct]);
                 __aarp_expire_all(&unresolved[ct]);
                 __aarp_expire_all(&proxies[ct]);
         }
         write_unlock_bh(&aarp_lock);
 }
 
 /*
  *        Create a new aarp entry.  This must use GFP_ATOMIC because it
  *        runs while holding spinlocks.
  */
 static struct aarp_entry *aarp_alloc(void)
 {
         struct aarp_entry *a = kmalloc(sizeof(*a), GFP_ATOMIC);
 
         if (a)
                 skb_queue_head_init(&a->packet_queue);
         return a;
 }
 
 /*
  * Find an entry. We might return an expired but not yet purged entry. We
  * don't care as it will do no harm.
  *
  * This must run under the aarp_lock.
  */
 static struct aarp_entry *__aarp_find_entry(struct aarp_entry *list,
                                             struct net_device *dev,
                                             struct atalk_addr *sat)
 {
         while (list) {
                 if (list->target_addr.s_net == sat->s_net &&
                     list->target_addr.s_node == sat->s_node &&
                     list->dev == dev)
                         break;
                 list = list->next;
         }
 
         return list;
 }
 
 /* Called from the DDP code, and thus must be exported. */
 void aarp_proxy_remove(struct net_device *dev, struct atalk_addr *sa)
 {
         int hash = sa->s_node % (AARP_HASH_SIZE - 1);
         struct aarp_entry *a;
 
         write_lock_bh(&aarp_lock);
 
         a = __aarp_find_entry(proxies[hash], dev, sa);
         if (a)
                 a->expires_at = jiffies - 1;
 
         write_unlock_bh(&aarp_lock);
 }
 
 /* This must run under aarp_lock. */
 static struct atalk_addr *__aarp_proxy_find(struct net_device *dev,
                                             struct atalk_addr *sa)
 {
         int hash = sa->s_node % (AARP_HASH_SIZE - 1);
         struct aarp_entry *a = __aarp_find_entry(proxies[hash], dev, sa);
 
         return a ? sa : NULL;
 }
 
 /*
  * Probe a Phase 1 device or a device that requires its Net:Node to
  * be set via an ioctl.
  */
 static void aarp_send_probe_phase1(struct atalk_iface *iface)
 {
         struct ifreq atreq;
         struct sockaddr_at *sa = (struct sockaddr_at *)&atreq.ifr_addr;
 
         sa->sat_addr.s_node = iface->address.s_node;
         sa->sat_addr.s_net = ntohs(iface->address.s_net);
 
         /* We pass the Net:Node to the drivers/cards by a Device ioctl. */
         if (!(iface->dev->do_ioctl(iface->dev, &atreq, SIOCSIFADDR))) {
                 (void)iface->dev->do_ioctl(iface->dev, &atreq, SIOCGIFADDR);
                 if (iface->address.s_net != htons(sa->sat_addr.s_net) ||
                     iface->address.s_node != sa->sat_addr.s_node)
                         iface->status |= ATIF_PROBE_FAIL;
 
                 iface->address.s_net  = htons(sa->sat_addr.s_net);
                 iface->address.s_node = sa->sat_addr.s_node;
         }
 }
 
 
 void aarp_probe_network(struct atalk_iface *atif)
 {
         if (atif->dev->type == ARPHRD_LOCALTLK ||
             atif->dev->type == ARPHRD_PPP)
                 aarp_send_probe_phase1(atif);
         else {
                 unsigned int count;
 
                 for (count = 0; count < AARP_RETRANSMIT_LIMIT; count++) {
                         aarp_send_probe(atif->dev, &atif->address);
 
                         /* Defer 1/10th */
                         msleep(100);
 
                         if (atif->status & ATIF_PROBE_FAIL)
                                 break;
                 }
         }
 }
 
 int aarp_proxy_probe_network(struct atalk_iface *atif, struct atalk_addr *sa)
 {
         int hash, retval = -EPROTONOSUPPORT;
         struct aarp_entry *entry;
         unsigned int count;
 
         /*
          * we don't currently support LocalTalk or PPP for proxy AARP;
          * if someone wants to try and add it, have fun
          */
         if (atif->dev->type == ARPHRD_LOCALTLK ||
             atif->dev->type == ARPHRD_PPP)
                 goto out;
 
         /*
          * create a new AARP entry with the flags set to be published --
          * we need this one to hang around even if it's in use
          */
         entry = aarp_alloc();
         retval = -ENOMEM;
         if (!entry)
                 goto out;
 
         entry->expires_at = -1;
         entry->status = ATIF_PROBE;
         entry->target_addr.s_node = sa->s_node;
         entry->target_addr.s_net = sa->s_net;
         entry->dev = atif->dev;
 
         write_lock_bh(&aarp_lock);
 
         hash = sa->s_node % (AARP_HASH_SIZE - 1);
         entry->next = proxies[hash];
         proxies[hash] = entry;
 
         for (count = 0; count < AARP_RETRANSMIT_LIMIT; count++) {
                 aarp_send_probe(atif->dev, sa);
 
                 /* Defer 1/10th */
                 write_unlock_bh(&aarp_lock);
                 msleep(100);
                 write_lock_bh(&aarp_lock);
 
                 if (entry->status & ATIF_PROBE_FAIL)
                         break;
         }
 
         if (entry->status & ATIF_PROBE_FAIL) {
                 entry->expires_at = jiffies - 1; /* free the entry */
                 retval = -EADDRINUSE; /* return network full */
         } else { /* clear the probing flag */
                 entry->status &= ~ATIF_PROBE;
                 retval = 1;
         }
 
         write_unlock_bh(&aarp_lock);
 out:
         return retval;
 }
 
 /* Send a DDP frame */
 int aarp_send_ddp(struct net_device *dev, struct sk_buff *skb,
                   struct atalk_addr *sa, void *hwaddr)
 {
         static char ddp_eth_multicast[ETH_ALEN] =
                 { 0x09, 0x00, 0x07, 0xFF, 0xFF, 0xFF };
         int hash;
         struct aarp_entry *a;
 
         skb_reset_network_header(skb);
 
         /* Check for LocalTalk first */
         if (dev->type == ARPHRD_LOCALTLK) {
                 struct atalk_addr *at = atalk_find_dev_addr(dev);
                 struct ddpehdr *ddp = (struct ddpehdr *)skb->data;
                 int ft = 2;
 
                 /*
                  * Compressible ?
                  *
                  * IFF: src_net == dest_net == device_net
                  * (zero matches anything)
                  */
 
                 if ((!ddp->deh_snet || at->s_net == ddp->deh_snet) &&
                     (!ddp->deh_dnet || at->s_net == ddp->deh_dnet)) {
                         skb_pull(skb, sizeof(*ddp) - 4);
 
                         /*
                          *        The upper two remaining bytes are the port
                          *        numbers        we just happen to need. Now put the
                          *        length in the lower two.
                          */
                         *((__be16 *)skb->data) = htons(skb->len);
                         ft = 1;
                 }
                 /*
                  * Nice and easy. No AARP type protocols occur here so we can
                  * just shovel it out with a 3 byte LLAP header
                  */
 
                 skb_push(skb, 3);
                 skb->data[0] = sa->s_node;
                 skb->data[1] = at->s_node;
                 skb->data[2] = ft;
                 skb->dev     = dev;
                 goto sendit;
         }
 
         /* On a PPP link we neither compress nor aarp.  */
         if (dev->type == ARPHRD_PPP) {
                 skb->protocol = htons(ETH_P_PPPTALK);
                 skb->dev = dev;
                 goto sendit;
         }
 
         /* Non ELAP we cannot do. */
         if (dev->type != ARPHRD_ETHER)
                 return -1;
 
         skb->dev = dev;
         skb->protocol = htons(ETH_P_ATALK);
         hash = sa->s_node % (AARP_HASH_SIZE - 1);
 
         /* Do we have a resolved entry? */
         if (sa->s_node == ATADDR_BCAST) {
                 /* Send it */
                 ddp_dl->request(ddp_dl, skb, ddp_eth_multicast);
                 goto sent;
         }
 
         write_lock_bh(&aarp_lock);
         a = __aarp_find_entry(resolved[hash], dev, sa);
 
         if (a) { /* Return 1 and fill in the address */
                 a->expires_at = jiffies + (sysctl_aarp_expiry_time * 10);
                 ddp_dl->request(ddp_dl, skb, a->hwaddr);
                 write_unlock_bh(&aarp_lock);
                 goto sent;
         }
 
         /* Do we have an unresolved entry: This is the less common path */
         a = __aarp_find_entry(unresolved[hash], dev, sa);
         if (a) { /* Queue onto the unresolved queue */
                 skb_queue_tail(&a->packet_queue, skb);
                 goto out_unlock;
         }
 
         /* Allocate a new entry */
         a = aarp_alloc();
         if (!a) {
                 /* Whoops slipped... good job it's an unreliable protocol 8) */
                 write_unlock_bh(&aarp_lock);
                 return -1;
         }
 
         /* Set up the queue */
         skb_queue_tail(&a->packet_queue, skb);
         a->expires_at         = jiffies + sysctl_aarp_resolve_time;
         a->dev                 = dev;
         a->next                 = unresolved[hash];
         a->target_addr         = *sa;
         a->xmit_count         = 0;
         unresolved[hash] = a;
         unresolved_count++;
 
         /* Send an initial request for the address */
         __aarp_send_query(a);
 
         /*
          * Switch to fast timer if needed (That is if this is the first
          * unresolved entry to get added)
          */
 
         if (unresolved_count == 1)
                 mod_timer(&aarp_timer, jiffies + sysctl_aarp_tick_time);
 
         /* Now finally, it is safe to drop the lock. */
 out_unlock:
         write_unlock_bh(&aarp_lock);
 
         /* Tell the ddp layer we have taken over for this frame. */
         return 0;
 
 sendit:
         if (skb->sk)
                 skb->priority = skb->sk->sk_priority;
         dev_queue_xmit(skb);
 sent:
         return 1;
 }
 
 /*
  *        An entry in the aarp unresolved queue has become resolved. Send
  *        all the frames queued under it.
  *
  *        Must run under aarp_lock.
  */
 static void __aarp_resolved(struct aarp_entry **list, struct aarp_entry *a,
                             int hash)
 {
         struct sk_buff *skb;
 
         while (*list)
                 if (*list == a) {
                         unresolved_count--;
                         *list = a->next;
 
                         /* Move into the resolved list */
                         a->next = resolved[hash];
                         resolved[hash] = a;
 
                         /* Kick frames off */
                         while ((skb = skb_dequeue(&a->packet_queue)) != NULL) {
                                 a->expires_at = jiffies +
                                                 sysctl_aarp_expiry_time * 10;
                                 ddp_dl->request(ddp_dl, skb, a->hwaddr);
                         }
                 } else
                         list = &((*list)->next);
 }
 
 /*
  *        This is called by the SNAP driver whenever we see an AARP SNAP
  *        frame. We currently only support Ethernet.
  */
 static int aarp_rcv(struct sk_buff *skb, struct net_device *dev,
                     struct packet_type *pt, struct net_device *orig_dev)
 {
         struct elapaarp *ea = aarp_hdr(skb);
         int hash, ret = 0;
         __u16 function;
         struct aarp_entry *a;
         struct atalk_addr sa, *ma, da;
         struct atalk_iface *ifa;
 
         if (!net_eq(dev_net(dev), &init_net))
                 goto out0;
 
         /* We only do Ethernet SNAP AARP. */
         if (dev->type != ARPHRD_ETHER)
                 goto out0;
 
         /* Frame size ok? */
         if (!skb_pull(skb, sizeof(*ea)))
                 goto out0;
 
         function = ntohs(ea->function);
 
         /* Sanity check fields. */
         if (function < AARP_REQUEST || function > AARP_PROBE ||
             ea->hw_len != ETH_ALEN || ea->pa_len != AARP_PA_ALEN ||
             ea->pa_src_zero || ea->pa_dst_zero)
                 goto out0;
 
         /* Looks good. */
         hash = ea->pa_src_node % (AARP_HASH_SIZE - 1);
 
         /* Build an address. */
         sa.s_node = ea->pa_src_node;
         sa.s_net = ea->pa_src_net;
 
         /* Process the packet. Check for replies of me. */
         ifa = atalk_find_dev(dev);
         if (!ifa)
                 goto out1;
 
         if (ifa->status & ATIF_PROBE &&
             ifa->address.s_node == ea->pa_dst_node &&
             ifa->address.s_net == ea->pa_dst_net) {
                 ifa->status |= ATIF_PROBE_FAIL; /* Fail the probe (in use) */
                 goto out1;
         }
 
         /* Check for replies of proxy AARP entries */
         da.s_node = ea->pa_dst_node;
         da.s_net  = ea->pa_dst_net;
 
         write_lock_bh(&aarp_lock);
         a = __aarp_find_entry(proxies[hash], dev, &da);
 
         if (a && a->status & ATIF_PROBE) {
                 a->status |= ATIF_PROBE_FAIL;
                 /*
                  * we do not respond to probe or request packets for
                  * this address while we are probing this address
                  */
                 goto unlock;
         }
 
         switch (function) {
                 case AARP_REPLY:
                         if (!unresolved_count)        /* Speed up */
                                 break;
 
                         /* Find the entry.  */
                         a = __aarp_find_entry(unresolved[hash], dev, &sa);
                         if (!a || dev != a->dev)
                                 break;
 
                         /* We can fill one in - this is good. */
                         memcpy(a->hwaddr, ea->hw_src, ETH_ALEN);
                         __aarp_resolved(&unresolved[hash], a, hash);
                         if (!unresolved_count)
                                 mod_timer(&aarp_timer,
                                           jiffies + sysctl_aarp_expiry_time);
                         break;
 
                 case AARP_REQUEST:
                 case AARP_PROBE:
 
                         /*
                          * If it is my address set ma to my address and reply.
                          * We can treat probe and request the same.  Probe
                          * simply means we shouldn't cache the querying host,
                          * as in a probe they are proposing an address not
                          * using one.
                          *
                          * Support for proxy-AARP added. We check if the
                          * address is one of our proxies before we toss the
                          * packet out.
                          */
 
                         sa.s_node = ea->pa_dst_node;
                         sa.s_net  = ea->pa_dst_net;
 
                         /* See if we have a matching proxy. */
                         ma = __aarp_proxy_find(dev, &sa);
                         if (!ma)
                                 ma = &ifa->address;
                         else { /* We need to make a copy of the entry. */
                                 da.s_node = sa.s_node;
                                 da.s_net = da.s_net;
                                 ma = &da;
                         }
 
                         if (function == AARP_PROBE) {
                                 /*
                                  * A probe implies someone trying to get an
                                  * address. So as a precaution flush any
                                  * entries we have for this address.
                                  */
                                 a = __aarp_find_entry(resolved[sa.s_node %
                                                           (AARP_HASH_SIZE - 1)],
                                                       skb->dev, &sa);
 
                                 /*
                                  * Make it expire next tick - that avoids us
                                  * getting into a probe/flush/learn/probe/
                                  * flush/learn cycle during probing of a slow
                                  * to respond host addr.
                                  */
                                 if (a) {
                                         a->expires_at = jiffies - 1;
                                         mod_timer(&aarp_timer, jiffies +
                                                         sysctl_aarp_tick_time);
                                 }
                         }
 
                         if (sa.s_node != ma->s_node)
                                 break;
 
                         if (sa.s_net && ma->s_net && sa.s_net != ma->s_net)
                                 break;
 
                         sa.s_node = ea->pa_src_node;
                         sa.s_net = ea->pa_src_net;
 
                         /* aarp_my_address has found the address to use for us.
                         */
                         aarp_send_reply(dev, ma, &sa, ea->hw_src);
                         break;
         }
 
 unlock:
         write_unlock_bh(&aarp_lock);
 out1:
         ret = 1;
 out0:
         kfree_skb(skb);
         return ret;
 }
 
 static struct notifier_block aarp_notifier = {
         .notifier_call = aarp_device_event,
 };
 
 static unsigned char aarp_snap_id[] = { 0x00, 0x00, 0x00, 0x80, 0xF3 };
 
 void __init aarp_proto_init(void)
 {
         aarp_dl = register_snap_client(aarp_snap_id, aarp_rcv);
         if (!aarp_dl)
                 printk(KERN_CRIT "Unable to register AARP with SNAP.\n");
         setup_timer(&aarp_timer, aarp_expire_timeout, 0);
         aarp_timer.expires  = jiffies + sysctl_aarp_expiry_time;
         add_timer(&aarp_timer);
         register_netdevice_notifier(&aarp_notifier);
 }
 
 /* Remove the AARP entries associated with a device. */
 void aarp_device_down(struct net_device *dev)
 {
         int ct;
 
         write_lock_bh(&aarp_lock);
 
         for (ct = 0; ct < AARP_HASH_SIZE; ct++) {
                 __aarp_expire_device(&resolved[ct], dev);
                 __aarp_expire_device(&unresolved[ct], dev);
                 __aarp_expire_device(&proxies[ct], dev);
         }
 
         write_unlock_bh(&aarp_lock);
 }
 
 #ifdef CONFIG_PROC_FS
 struct aarp_iter_state {
         int bucket;
         struct aarp_entry **table;
 };
 
 /*
  * Get the aarp entry that is in the chain described
  * by the iterator.
  * If pos is set then skip till that index.
  * pos = 1 is the first entry
  */
 static struct aarp_entry *iter_next(struct aarp_iter_state *iter, loff_t *pos)
 {
         int ct = iter->bucket;
         struct aarp_entry **table = iter->table;
         loff_t off = 0;
         struct aarp_entry *entry;
 
  rescan:
         while(ct < AARP_HASH_SIZE) {
                 for (entry = table[ct]; entry; entry = entry->next) {
                         if (!pos || ++off == *pos) {
                                 iter->table = table;
                                 iter->bucket = ct;
                                 return entry;
                         }
                 }
                 ++ct;
         }
 
         if (table == resolved) {
                 ct = 0;
                 table = unresolved;
                 goto rescan;
         }
         if (table == unresolved) {
                 ct = 0;
                 table = proxies;
                 goto rescan;
         }
         return NULL;
 }
 
 static void *aarp_seq_start(struct seq_file *seq, loff_t *pos)
         __acquires(aarp_lock)
 {
         struct aarp_iter_state *iter = seq->private;
 
         read_lock_bh(&aarp_lock);
         iter->table     = resolved;
         iter->bucket    = 0;
 
         return *pos ? iter_next(iter, pos) : SEQ_START_TOKEN;
 }
 
 static void *aarp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 {
         struct aarp_entry *entry = v;
         struct aarp_iter_state *iter = seq->private;
 
         ++*pos;
 
         /* first line after header */
         if (v == SEQ_START_TOKEN)
                 entry = iter_next(iter, NULL);
 
         /* next entry in current bucket */
         else if (entry->next)
                 entry = entry->next;
 
         /* next bucket or table */
         else {
                 ++iter->bucket;
                 entry = iter_next(iter, NULL);
         }
         return entry;
 }
 
 static void aarp_seq_stop(struct seq_file *seq, void *v)
         __releases(aarp_lock)
 {
         read_unlock_bh(&aarp_lock);
 }
 
 static const char *dt2str(unsigned long ticks)
 {
         static char buf[32];
 
         sprintf(buf, "%ld.%02ld", ticks / HZ, ((ticks % HZ) * 100 ) / HZ);
 
         return buf;
 }
 
 static int aarp_seq_show(struct seq_file *seq, void *v)
 {
         struct aarp_iter_state *iter = seq->private;
         struct aarp_entry *entry = v;
         unsigned long now = jiffies;
         DECLARE_MAC_BUF(mac);
 
        if (v == SEQ_START_TOKEN)
                seq_puts(seq,
                         "Address  Interface   Hardware Address"
                         "   Expires LastSend  Retry Status\n");
        else {
                seq_printf(seq, "%04X:%02X  %-12s",
                           ntohs(entry->target_addr.s_net),
                           (unsigned int) entry->target_addr.s_node,
                           entry->dev ? entry->dev->name : "????");
                seq_printf(seq, "%s", print_mac(mac, entry->hwaddr));
                seq_printf(seq, " %8s",
                           dt2str((long)entry->expires_at - (long)now));
                if (iter->table == unresolved)
                        seq_printf(seq, " %8s %6hu",
                                   dt2str(now - entry->last_sent),
                                   entry->xmit_count);
                else
                        seq_puts(seq, "                ");
                seq_printf(seq, " %s\n",
                           (iter->table == resolved) ? "resolved"
                           : (iter->table == unresolved) ? "unresolved"
                           : (iter->table == proxies) ? "proxies"
                           : "unknown");
        }
        return 0;
}

static const struct seq_operations aarp_seq_ops = {
        .start  = aarp_seq_start,
        .next   = aarp_seq_next,
        .stop   = aarp_seq_stop,
        .show   = aarp_seq_show,
};

static int aarp_seq_open(struct inode *inode, struct file *file)
{
        return seq_open_private(file, &aarp_seq_ops,
                        sizeof(struct aarp_iter_state));
}

const struct file_operations atalk_seq_arp_fops = {
        .owner                = THIS_MODULE,
        .open           = aarp_seq_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release_private,
};
#endif

/* General module cleanup. Called from cleanup_module() in ddp.c. */
void aarp_cleanup_module(void)
{
        del_timer_sync(&aarp_timer);
        unregister_netdevice_notifier(&aarp_notifier);
        unregister_snap_client(aarp_dl);
        aarp_purge();
}