dn_neigh.c

linux 内核源代码

/*
 * DECnet       An implementation of the DECnet protocol suite for the LINUX
 *              operating system.  DECnet is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              DECnet Neighbour Functions (Adjacency Database and
 *                                                        On-Ethernet Cache)
 *
 * Author:      Steve Whitehouse <[e-mail]>
 *
 *
 * Changes:
 *     Steve Whitehouse     : Fixed router listing routine
 *     Steve Whitehouse     : Added error_report functions
 *     Steve Whitehouse     : Added default router detection
 *     Steve Whitehouse     : Hop counts in outgoing messages
 *     Steve Whitehouse     : Fixed src/dst in outgoing messages so
 *                            forwarding now stands a good chance of
 *                            working.
 *     Steve Whitehouse     : Fixed neighbour states (for now anyway).
 *     Steve Whitehouse     : Made error_report functions dummies. This
 *                            is not the right place to return skbs.
 *     Steve Whitehouse     : Convert to seq_file
 *
 */

#include <linux/net.h>
#include <linux/module.h>
#include <linux/socket.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/string.h>
#include <linux/netfilter_decnet.h>
#include <linux/spinlock.h>
#include <linux/seq_file.h>
#include <linux/rcupdate.h>
#include <linux/jhash.h>
#include <asm/atomic.h>
#include <net/net_namespace.h>
#include <net/neighbour.h>
#include <net/dst.h>
#include <net/flow.h>
#include <net/dn.h>
#include <net/dn_dev.h>
#include <net/dn_neigh.h>
#include <net/dn_route.h>

static u32 dn_neigh_hash(const void *pkey, const struct net_device *dev);
static int dn_neigh_construct(struct neighbour *);
static void dn_long_error_report(struct neighbour *, struct sk_buff *);
static void dn_short_error_report(struct neighbour *, struct sk_buff *);
static int dn_long_output(struct sk_buff *);
static int dn_short_output(struct sk_buff *);
static int dn_phase3_output(struct sk_buff *);


/*
 * For talking to broadcast devices: Ethernet & PPP
 */
static struct neigh_ops dn_long_ops = {
	.family =		AF_DECnet,
	.error_report =		dn_long_error_report,
	.output =		dn_long_output,
	.connected_output =	dn_long_output,
	.hh_output =		dev_queue_xmit,
	.queue_xmit =		dev_queue_xmit,
};

/*
 * For talking to pointopoint and multidrop devices: DDCMP and X.25
 */
static struct neigh_ops dn_short_ops = {
	.family =		AF_DECnet,
	.error_report =		dn_short_error_report,
	.output =		dn_short_output,
	.connected_output =	dn_short_output,
	.hh_output =		dev_queue_xmit,
	.queue_xmit =		dev_queue_xmit,
};

/*
 * For talking to DECnet phase III nodes
 */
static struct neigh_ops dn_phase3_ops = {
	.family =		AF_DECnet,
	.error_report =		dn_short_error_report, /* Can use short version here */
	.output =		dn_phase3_output,
	.connected_output =	dn_phase3_output,
	.hh_output =		dev_queue_xmit,
	.queue_xmit =		dev_queue_xmit
};

struct neigh_table dn_neigh_table = {
	.family =			PF_DECnet,
	.entry_size =			sizeof(struct dn_neigh),
	.key_len =			sizeof(__le16),
	.hash =				dn_neigh_hash,
	.constructor =			dn_neigh_construct,
	.id =				"dn_neigh_cache",
	.parms ={
		.tbl =			&dn_neigh_table,
		.base_reachable_time =	30 * HZ,
		.retrans_time =	1 * HZ,
		.gc_staletime =	60 * HZ,
		.reachable_time =		30 * HZ,
		.delay_probe_time =	5 * HZ,
		.queue_len =		3,
		.ucast_probes =	0,
		.app_probes =		0,
		.mcast_probes =	0,
		.anycast_delay =	0,
		.proxy_delay =		0,
		.proxy_qlen =		0,
		.locktime =		1 * HZ,
	},
	.gc_interval =			30 * HZ,
	.gc_thresh1 =			128,
	.gc_thresh2 =			512,
	.gc_thresh3 =			1024,
};

static u32 dn_neigh_hash(const void *pkey, const struct net_device *dev)
{
	return jhash_2words(*(__u16 *)pkey, 0, dn_neigh_table.hash_rnd);
}

static int dn_neigh_construct(struct neighbour *neigh)
{
	struct net_device *dev = neigh->dev;
	struct dn_neigh *dn = (struct dn_neigh *)neigh;
	struct dn_dev *dn_db;
	struct neigh_parms *parms;

	rcu_read_lock();
	dn_db = rcu_dereference(dev->dn_ptr);
	if (dn_db == NULL) {
		rcu_read_unlock();
		return -EINVAL;
	}

	parms = dn_db->neigh_parms;
	if (!parms) {
		rcu_read_unlock();
		return -EINVAL;
	}

	__neigh_parms_put(neigh->parms);
	neigh->parms = neigh_parms_clone(parms);

	if (dn_db->use_long)
		neigh->ops = &dn_long_ops;
	else
		neigh->ops = &dn_short_ops;
	rcu_read_unlock();

	if (dn->flags & DN_NDFLAG_P3)
		neigh->ops = &dn_phase3_ops;

	neigh->nud_state = NUD_NOARP;
	neigh->output = neigh->ops->connected_output;

	if ((dev->type == ARPHRD_IPGRE) || (dev->flags & IFF_POINTOPOINT))
		memcpy(neigh->ha, dev->broadcast, dev->addr_len);
	else if ((dev->type == ARPHRD_ETHER) || (dev->type == ARPHRD_LOOPBACK))
		dn_dn2eth(neigh->ha, dn->addr);
	else {
		if (net_ratelimit())
			printk(KERN_DEBUG "Trying to create neigh for hw %d\n",  dev->type);
		return -EINVAL;
	}

	/*
	 * Make an estimate of the remote block size by assuming that its
	 * two less then the device mtu, which it true for ethernet (and
	 * other things which support long format headers) since there is
	 * an extra length field (of 16 bits) which isn't part of the
	 * ethernet headers and which the DECnet specs won't admit is part
	 * of the DECnet routing headers either.
	 *
	 * If we over estimate here its no big deal, the NSP negotiations
	 * will prevent us from sending packets which are too large for the
	 * remote node to handle. In any case this figure is normally updated
	 * by a hello message in most cases.
	 */
	dn->blksize = dev->mtu - 2;

	return 0;
}

static void dn_long_error_report(struct neighbour *neigh, struct sk_buff *skb)
{
	printk(KERN_DEBUG "dn_long_error_report: called\n");
	kfree_skb(skb);
}


static void dn_short_error_report(struct neighbour *neigh, struct sk_buff *skb)
{
	printk(KERN_DEBUG "dn_short_error_report: called\n");
	kfree_skb(skb);
}

static int dn_neigh_output_packet(struct sk_buff *skb)
{
	struct dst_entry *dst = skb->dst;
	struct dn_route *rt = (struct dn_route *)dst;
	struct neighbour *neigh = dst->neighbour;
	struct net_device *dev = neigh->dev;
	char mac_addr[ETH_ALEN];

	dn_dn2eth(mac_addr, rt->rt_local_src);
	if (dev_hard_header(skb, dev, ntohs(skb->protocol), neigh->ha,
			    mac_addr, skb->len) >= 0)
		return neigh->ops->queue_xmit(skb);

	if (net_ratelimit())
		printk(KERN_DEBUG "dn_neigh_output_packet: oops, can't send packet\n");

	kfree_skb(skb);
	return -EINVAL;
}

static int dn_long_output(struct sk_buff *skb)
{
	struct dst_entry *dst = skb->dst;
	struct neighbour *neigh = dst->neighbour;
	struct net_device *dev = neigh->dev;
	int headroom = dev->hard_header_len + sizeof(struct dn_long_packet) + 3;
	unsigned char *data;
	struct dn_long_packet *lp;
	struct dn_skb_cb *cb = DN_SKB_CB(skb);


	if (skb_headroom(skb) < headroom) {
		struct sk_buff *skb2 = skb_realloc_headroom(skb, headroom);
		if (skb2 == NULL) {
			if (net_ratelimit())
				printk(KERN_CRIT "dn_long_output: no memory\n");
			kfree_skb(skb);
			return -ENOBUFS;
		}
		kfree_skb(skb);
		skb = skb2;
		if (net_ratelimit())
			printk(KERN_INFO "dn_long_output: Increasing headroom\n");
	}

	data = skb_push(skb, sizeof(struct dn_long_packet) + 3);
	lp = (struct dn_long_packet *)(data+3);

	*((__le16 *)data) = dn_htons(skb->len - 2);
	*(data + 2) = 1 | DN_RT_F_PF; /* Padding */

	lp->msgflg   = DN_RT_PKT_LONG|(cb->rt_flags&(DN_RT_F_IE|DN_RT_F_RQR|DN_RT_F_RTS));
	lp->d_area   = lp->d_subarea = 0;
	dn_dn2eth(lp->d_id, cb->dst);
	lp->s_area   = lp->s_subarea = 0;
	dn_dn2eth(lp->s_id, cb->src);
	lp->nl2      = 0;
	lp->visit_ct = cb->hops & 0x3f;
	lp->s_class  = 0;
	lp->pt       = 0;

	skb_reset_network_header(skb);

	return NF_HOOK(PF_DECnet, NF_DN_POST_ROUTING, skb, NULL, neigh->dev, dn_neigh_output_packet);
}

static int dn_short_output(struct sk_buff *skb)
{
	struct dst_entry *dst = skb->dst;
	struct neighbour *neigh = dst->neighbour;
	struct net_device *dev = neigh->dev;
	int headroom = dev->hard_header_len + sizeof(struct dn_short_packet) + 2;
	struct dn_short_packet *sp;
	unsigned char *data;
	struct dn_skb_cb *cb = DN_SKB_CB(skb);


	if (skb_headroom(skb) < headroom) {
		struct sk_buff *skb2 = skb_realloc_headroom(skb, headroom);
		if (skb2 == NULL) {
			if (net_ratelimit())
				printk(KERN_CRIT "dn_short_output: no memory\n");
			kfree_skb(skb);
			return -ENOBUFS;
		}
		kfree_skb(skb);
		skb = skb2;
		if (net_ratelimit())
			printk(KERN_INFO "dn_short_output: Increasing headroom\n");
	}

	data = skb_push(skb, sizeof(struct dn_short_packet) + 2);
	*((__le16 *)data) = dn_htons(skb->len - 2);
	sp = (struct dn_short_packet *)(data+2);

	sp->msgflg     = DN_RT_PKT_SHORT|(cb->rt_flags&(DN_RT_F_RQR|DN_RT_F_RTS));
	sp->dstnode    = cb->dst;
	sp->srcnode    = cb->src;
	sp->forward    = cb->hops & 0x3f;