path: root/net/appletalk/aarp.c

/*
 *	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 *