nr_route.c

linux 内核源代码

/*
 * 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.
 *
 * Copyright Jonathan Naylor G4KLX ([e-mail])
 * Copyright Alan Cox GW4PTS ([e-mail])
 * Copyright Tomi Manninen OH2BNS ([e-mail])
 */
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <net/arp.h>
#include <linux/if_arp.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/termios.h>	/* For TIOCINQ/OUTQ */
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/netfilter.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <net/netrom.h>
#include <linux/seq_file.h>

static unsigned int nr_neigh_no = 1;

static HLIST_HEAD(nr_node_list);
static DEFINE_SPINLOCK(nr_node_list_lock);
static HLIST_HEAD(nr_neigh_list);
static DEFINE_SPINLOCK(nr_neigh_list_lock);

static struct nr_node *nr_node_get(ax25_address *callsign)
{
	struct nr_node *found = NULL;
	struct nr_node *nr_node;
	struct hlist_node *node;

	spin_lock_bh(&nr_node_list_lock);
	nr_node_for_each(nr_node, node, &nr_node_list)
		if (ax25cmp(callsign, &nr_node->callsign) == 0) {
			nr_node_hold(nr_node);
			found = nr_node;
			break;
		}
	spin_unlock_bh(&nr_node_list_lock);
	return found;
}

static struct nr_neigh *nr_neigh_get_dev(ax25_address *callsign,
					 struct net_device *dev)
{
	struct nr_neigh *found = NULL;
	struct nr_neigh *nr_neigh;
	struct hlist_node *node;

	spin_lock_bh(&nr_neigh_list_lock);
	nr_neigh_for_each(nr_neigh, node, &nr_neigh_list)
		if (ax25cmp(callsign, &nr_neigh->callsign) == 0 &&
		    nr_neigh->dev == dev) {
			nr_neigh_hold(nr_neigh);
			found = nr_neigh;
			break;
		}
	spin_unlock_bh(&nr_neigh_list_lock);
	return found;
}

static void nr_remove_neigh(struct nr_neigh *);

/*
 *	Add a new route to a node, and in the process add the node and the
 *	neighbour if it is new.
 */
static int __must_check nr_add_node(ax25_address *nr, const char *mnemonic,
	ax25_address *ax25, ax25_digi *ax25_digi, struct net_device *dev,
	int quality, int obs_count)
{
	struct nr_node  *nr_node;
	struct nr_neigh *nr_neigh;
	struct nr_route nr_route;
	int i, found;
	struct net_device *odev;

	if ((odev=nr_dev_get(nr)) != NULL) {	/* Can't add routes to ourself */
		dev_put(odev);
		return -EINVAL;
	}

	nr_node = nr_node_get(nr);

	nr_neigh = nr_neigh_get_dev(ax25, dev);

	/*
	 * The L2 link to a neighbour has failed in the past
	 * and now a frame comes from this neighbour. We assume
	 * it was a temporary trouble with the link and reset the
	 * routes now (and not wait for a node broadcast).
	 */
	if (nr_neigh != NULL && nr_neigh->failed != 0 && quality == 0) {
		struct nr_node *nr_nodet;
		struct hlist_node *node;

		spin_lock_bh(&nr_node_list_lock);
		nr_node_for_each(nr_nodet, node, &nr_node_list) {
			nr_node_lock(nr_nodet);
			for (i = 0; i < nr_nodet->count; i++)
				if (nr_nodet->routes[i].neighbour == nr_neigh)
					if (i < nr_nodet->which)
						nr_nodet->which = i;
			nr_node_unlock(nr_nodet);
		}
		spin_unlock_bh(&nr_node_list_lock);
	}

	if (nr_neigh != NULL)
		nr_neigh->failed = 0;

	if (quality == 0 && nr_neigh != NULL && nr_node != NULL) {
		nr_neigh_put(nr_neigh);
		nr_node_put(nr_node);
		return 0;
	}

	if (nr_neigh == NULL) {
		if ((nr_neigh = kmalloc(sizeof(*nr_neigh), GFP_ATOMIC)) == NULL) {
			if (nr_node)
				nr_node_put(nr_node);
			return -ENOMEM;
		}

		nr_neigh->callsign = *ax25;
		nr_neigh->digipeat = NULL;
		nr_neigh->ax25     = NULL;
		nr_neigh->dev      = dev;
		nr_neigh->quality  = sysctl_netrom_default_path_quality;
		nr_neigh->locked   = 0;
		nr_neigh->count    = 0;
		nr_neigh->number   = nr_neigh_no++;
		nr_neigh->failed   = 0;
		atomic_set(&nr_neigh->refcount, 1);

		if (ax25_digi != NULL && ax25_digi->ndigi > 0) {
			nr_neigh->digipeat = kmemdup(ax25_digi,
						     sizeof(*ax25_digi),
						     GFP_KERNEL);
			if (nr_neigh->digipeat == NULL) {
				kfree(nr_neigh);
				if (nr_node)
					nr_node_put(nr_node);
				return -ENOMEM;
			}
		}

		spin_lock_bh(&nr_neigh_list_lock);
		hlist_add_head(&nr_neigh->neigh_node, &nr_neigh_list);
		nr_neigh_hold(nr_neigh);
		spin_unlock_bh(&nr_neigh_list_lock);
	}

	if (quality != 0 && ax25cmp(nr, ax25) == 0 && !nr_neigh->locked)
		nr_neigh->quality = quality;

	if (nr_node == NULL) {
		if ((nr_node = kmalloc(sizeof(*nr_node), GFP_ATOMIC)) == NULL) {
			if (nr_neigh)
				nr_neigh_put(nr_neigh);
			return -ENOMEM;
		}

		nr_node->callsign = *nr;
		strcpy(nr_node->mnemonic, mnemonic);

		nr_node->which = 0;
		nr_node->count = 1;
		atomic_set(&nr_node->refcount, 1);
		spin_lock_init(&nr_node->node_lock);

		nr_node->routes[0].quality   = quality;
		nr_node->routes[0].obs_count = obs_count;
		nr_node->routes[0].neighbour = nr_neigh;

		nr_neigh_hold(nr_neigh);
		nr_neigh->count++;

		spin_lock_bh(&nr_node_list_lock);
		hlist_add_head(&nr_node->node_node, &nr_node_list);
		/* refcount initialized at 1 */
		spin_unlock_bh(&nr_node_list_lock);

		return 0;
	}
	nr_node_lock(nr_node);

	if (quality != 0)
		strcpy(nr_node->mnemonic, mnemonic);

	for (found = 0, i = 0; i < nr_node->count; i++) {
		if (nr_node->routes[i].neighbour == nr_neigh) {
			nr_node->routes[i].quality   = quality;
			nr_node->routes[i].obs_count = obs_count;
			found = 1;
			break;
		}
	}

	if (!found) {
		/* We have space at the bottom, slot it in */
		if (nr_node->count < 3) {
			nr_node->routes[2] = nr_node->routes[1];
			nr_node->routes[1] = nr_node->routes[0];

			nr_node->routes[0].quality   = quality;
			nr_node->routes[0].obs_count = obs_count;
			nr_node->routes[0].neighbour = nr_neigh;

			nr_node->which++;
			nr_node->count++;
			nr_neigh_hold(nr_neigh);
			nr_neigh->count++;
		} else {
			/* It must be better than the worst */
			if (quality > nr_node->routes[2].quality) {
				nr_node->routes[2].neighbour->count--;
				nr_neigh_put(nr_node->routes[2].neighbour);

				if (nr_node->routes[2].neighbour->count == 0 && !nr_node->routes[2].neighbour->locked)
					nr_remove_neigh(nr_node->routes[2].neighbour);

				nr_node->routes[2].quality   = quality;
				nr_node->routes[2].obs_count = obs_count;
				nr_node->routes[2].neighbour = nr_neigh;

				nr_neigh_hold(nr_neigh);
				nr_neigh->count++;
			}
		}
	}

	/* Now re-sort the routes in quality order */
	switch (nr_node->count) {
	case 3:
		if (nr_node->routes[1].quality > nr_node->routes[0].quality) {
			switch (nr_node->which) {
				case 0:  nr_node->which = 1; break;
				case 1:  nr_node->which = 0; break;
				default: break;
			}
			nr_route           = nr_node->routes[0];
			nr_node->routes[0] = nr_node->routes[1];
			nr_node->routes[1] = nr_route;
		}
		if (nr_node->routes[2].quality > nr_node->routes[1].quality) {
			switch (nr_node->which) {
			case 1:  nr_node->which = 2;
				break;

			case 2:  nr_node->which = 1;
				break;

			default:
				break;
			}
			nr_route           = nr_node->routes[1];
			nr_node->routes[1] = nr_node->routes[2];
			nr_node->routes[2] = nr_route;
		}
	case 2:
		if (nr_node->routes[1].quality > nr_node->routes[0].quality) {
			switch (nr_node->which) {
			case 0:  nr_node->which = 1;
				break;

			case 1:  nr_node->which = 0;
				break;

			default: break;
			}
			nr_route           = nr_node->routes[0];
			nr_node->routes[0] = nr_node->routes[1];
			nr_node->routes[1] = nr_route;
			}
	case 1:
		break;
	}

	for (i = 0; i < nr_node->count; i++) {
		if (nr_node->routes[i].neighbour == nr_neigh) {
			if (i < nr_node->which)
				nr_node->which = i;
			break;
		}
	}

	nr_neigh_put(nr_neigh);
	nr_node_unlock(nr_node);
	nr_node_put(nr_node);
	return 0;
}

static inline void __nr_remove_node(struct nr_node *nr_node)
{
	hlist_del_init(&nr_node->node_node);
	nr_node_put(nr_node);
}

#define nr_remove_node_locked(__node) \
	__nr_remove_node(__node)

static void nr_remove_node(struct nr_node *nr_node)
{
	spin_lock_bh(&nr_node_list_lock);
	__nr_remove_node(nr_node);
	spin_unlock_bh(&nr_node_list_lock);
}

static inline void __nr_remove_neigh(struct nr_neigh *nr_neigh)
{
	hlist_del_init(&nr_neigh->neigh_node);
	nr_neigh_put(nr_neigh);
}

#define nr_remove_neigh_locked(__neigh) \
	__nr_remove_neigh(__neigh)

static void nr_remove_neigh(struct nr_neigh *nr_neigh)
{
	spin_lock_bh(&nr_neigh_list_lock);
	__nr_remove_neigh(nr_neigh);
	spin_unlock_bh(&nr_neigh_list_lock);
}

/*
 *	"Delete" a node. Strictly speaking remove a route to a node. The node
 *	is only deleted if no routes are left to it.
 */
static int nr_del_node(ax25_address *callsign, ax25_address *neighbour, struct net_device *dev)
{
	struct nr_node  *nr_node;
	struct nr_neigh *nr_neigh;
	int i;

	nr_node = nr_node_get(callsign);

	if (nr_node == NULL)
		return -EINVAL;

	nr_neigh = nr_neigh_get_dev(neighbour, dev);

	if (nr_neigh == NULL) {
		nr_node_put(nr_node);
		return -EINVAL;
	}

	nr_node_lock(nr_node);
	for (i = 0; i < nr_node->count; i++) {
		if (nr_node->routes[i].neighbour == nr_neigh) {
			nr_neigh->count--;
			nr_neigh_put(nr_neigh);

			if (nr_neigh->count == 0 && !nr_neigh->locked)
				nr_remove_neigh(nr_neigh);
			nr_neigh_put(nr_neigh);

			nr_node->count--;

			if (nr_node->count == 0) {
				nr_remove_node(nr_node);
			} else {
				switch (i) {
				case 0:
					nr_node->routes[0] = nr_node->routes[1];
				case 1:
					nr_node->routes[1] = nr_node->routes[2];
				case 2:
					break;
				}
				nr_node_put(nr_node);
			}
			nr_node_unlock(nr_node);

			return 0;
		}
	}
	nr_neigh_put(nr_neigh);
	nr_node_unlock(nr_node);
	nr_node_put(nr_node);

	return -EINVAL;
}

/*
 *	Lock a neighbour with a quality.
 */
static int __must_check nr_add_neigh(ax25_address *callsign,
	ax25_digi *ax25_digi, struct net_device *dev, unsigned int quality)
{
	struct nr_neigh *nr_neigh;

	nr_neigh = nr_neigh_get_dev(callsign, dev);
	if (nr_neigh) {
		nr_neigh->quality = quality;
		nr_neigh->locked  = 1;
		nr_neigh_put(nr_neigh);
		return 0;
	}

	if ((nr_neigh = kmalloc(sizeof(*nr_neigh), GFP_ATOMIC)) == NULL)
		return -ENOMEM;

	nr_neigh->callsign = *callsign;
	nr_neigh->digipeat = NULL;
	nr_neigh->ax25     = NULL;
	nr_neigh->dev      = dev;
	nr_neigh->quality  = quality;
	nr_neigh->locked   = 1;
	nr_neigh->count    = 0;
	nr_neigh->number   = nr_neigh_no++;
	nr_neigh->failed   = 0;
	atomic_set(&nr_neigh->refcount, 1);

	if (ax25_digi != NULL && ax25_digi->ndigi > 0) {
		nr_neigh->digipeat = kmemdup(ax25_digi, sizeof(*ax25_digi),
					     GFP_KERNEL);
		if (nr_neigh->digipeat == NULL) {
			kfree(nr_neigh);
			return -ENOMEM;
		}
	}

	spin_lock_bh(&nr_neigh_list_lock);
	hlist_add_head(&nr_neigh->neigh_node, &nr_neigh_list);
	/* refcount is initialized at 1 */
	spin_unlock_bh(&nr_neigh_list_lock);

	return 0;
}

/*
 *	"Delete" a neighbour. The neighbour is only removed if the number
 *	of nodes that may use it is zero.
 */
static int nr_del_neigh(ax25_address *callsign, struct net_device *dev, unsigned int quality)
{
	struct nr_neigh *nr_neigh;

	nr_neigh = nr_neigh_get_dev(callsign, dev);

	if (nr_neigh == NULL) return -EINVAL;

	nr_neigh->quality = quality;
	nr_neigh->locked  = 0;

	if (nr_neigh->count == 0)
		nr_remove_neigh(nr_neigh);
	nr_neigh_put(nr_neigh);

	return 0;
}

/*
 *	Decrement the obsolescence count by one. If a route is reduced to a
 *	count of zero, remove it. Also remove any unlocked neighbours with
 *	zero nodes routing via it.
 */
static int nr_dec_obs(void)
{
	struct nr_neigh *nr_neigh;
	struct nr_node  *s;
	struct hlist_node *node, *nodet;
	int i;

	spin_lock_bh(&nr_node_list_lock);
	nr_node_for_each_safe(s, node, nodet, &nr_node_list) {
		nr_node_lock(s);
		for (i = 0; i < s->count; i++) {
			switch (s->routes[i].obs_count) {
			case 0:		/* A locked entry */
				break;

			case 1:		/* From 1 -> 0 */
				nr_neigh = s->routes[i].neighbour;

				nr_neigh->count--;
				nr_neigh_put(nr_neigh);

				if (nr_neigh->count == 0 && !nr_neigh->locked)
					nr_remove_neigh(nr_neigh);

				s->count--;

				switch (i) {
					case 0:
						s->routes[0] = s->routes[1];
					case 1:
						s->routes[1] = s->routes[2];
					case 2:
						break;
				}
				break;

			default:
				s->routes[i].obs_count--;
				break;

			}
		}

		if (s->count <= 0)
			nr_remove_node_locked(s);
		nr_node_unlock(s);
	}
	spin_unlock_bh(&nr_node_list_lock);

	return 0;