/*
 *	Forwarding database
 *	Linux ethernet bridge
 *
 *	Authors:
 *	Lennert Buytenhek		<buytenh@gnu.org>
 *
 *	$Id: br_fdb.c,v 1.4 2000/02/24 06:16:45 davem Exp $
 *
 *	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/kernel.h>
#include <linux/spinlock.h>
#include <linux/if_bridge.h>
#include <asm/atomic.h>
#include <asm/uaccess.h>
#include "br_private.h"

static __inline__ unsigned long __timeout(struct net_bridge *br)
{
	unsigned long timeout;

	timeout = jiffies - br->ageing_time;
	if (br->topology_change)
		timeout = jiffies - br->forward_delay;

	return timeout;
}

static __inline__ int has_expired(struct net_bridge *br,
				  struct net_bridge_fdb_entry *fdb)
{
	if (!fdb->is_static &&
	    time_before_eq(fdb->ageing_timer, __timeout(br)))
		return 1;

	return 0;
}

static __inline__ void copy_fdb(struct __fdb_entry *ent, struct net_bridge_fdb_entry *f)
{
	memcpy(ent->mac_addr, f->addr.addr, ETH_ALEN);
	ent->port_no = f->dst?f->dst->port_no:0;
	ent->is_local = f->is_local;
	ent->ageing_timer_value = 0;
	if (!f->is_static)
		ent->ageing_timer_value = jiffies - f->ageing_timer;
}

static __inline__ int br_mac_hash(unsigned char *mac)
{
	unsigned long x;

	x = mac[0];
	x = (x << 2) ^ mac[1];
	x = (x << 2) ^ mac[2];
	x = (x << 2) ^ mac[3];
	x = (x << 2) ^ mac[4];
	x = (x << 2) ^ mac[5];

	x ^= x >> 8;

	return x & (BR_HASH_SIZE - 1);
}

static __inline__ void __hash_link(struct net_bridge *br,
				   struct net_bridge_fdb_entry *ent,
				   int hash)
{
	ent->next_hash = br->hash[hash];
	if (ent->next_hash != NULL)
		ent->next_hash->pprev_hash = &ent->next_hash;
	br->hash[hash] = ent;
	ent->pprev_hash = &br->hash[hash];
}

static __inline__ void __hash_unlink(struct net_bridge_fdb_entry *ent)
{
	*(ent->pprev_hash) = ent->next_hash;
	if (ent->next_hash != NULL)
		ent->next_hash->pprev_hash = ent->pprev_hash;
	ent->next_hash = NULL;
	ent->pprev_hash = NULL;
}



void br_fdb_changeaddr(struct net_bridge_port *p, unsigned char *newaddr)
{
	struct net_bridge *br;
	int i;

	br = p->br;
	write_lock_bh(&br->hash_lock);
	for (i=0;i<BR_HASH_SIZE;i++) {
		struct net_bridge_fdb_entry *f;

		f = br->hash[i];
		while (f != NULL) {
			if (f->dst == p && f->is_local) {
				__hash_unlink(f);
				memcpy(f->addr.addr, newaddr, ETH_ALEN);
				__hash_link(br, f, br_mac_hash(newaddr));
				write_unlock_bh(&br->hash_lock);
				return;
			}
			f = f->next_hash;
		}
	}
	write_unlock_bh(&br->hash_lock);
}

void br_fdb_cleanup(struct net_bridge *br)
{
	int i;
	unsigned long timeout;

	timeout = __timeout(br);

	write_lock_bh(&br->hash_lock);
	for (i=0;i<BR_HASH_SIZE;i++) {
		struct net_bridge_fdb_entry *f;

		f = br->hash[i];
		while (f != NULL) {
			struct net_bridge_fdb_entry *g;

			g = f->next_hash;
			if (!f->is_static &&
			    time_before_eq(f->ageing_timer, timeout)) {
				__hash_unlink(f);
				br_fdb_put(f);
			}
			f = g;
		}
	}
	write_unlock_bh(&br->hash_lock);
}

void br_fdb_delete_by_port(struct net_bridge *br, struct net_bridge_port *p)
{
	int i;

	write_lock_bh(&br->hash_lock);
	for (i=0;i<BR_HASH_SIZE;i++) {
		struct net_bridge_fdb_entry *f;

		f = br->hash[i];
		while (f != NULL) {
			struct net_bridge_fdb_entry *g;

			g = f->next_hash;
			if (f->dst == p) {
				__hash_unlink(f);
				br_fdb_put(f);
			}
			f = g;
		}
	}
	write_unlock_bh(&br->hash_lock);
}

struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br, unsigned char *addr)
{
	struct net_bridge_fdb_entry *fdb;

	read_lock_bh(&br->hash_lock);
	fdb = br->hash[br_mac_hash(addr)];
	while (fdb != NULL) {
		if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
			if (!has_expired(br, fdb)) {
				atomic_inc(&fdb->use_count);
				read_unlock_bh(&br->hash_lock);
				return fdb;
			}

			read_unlock_bh(&br->hash_lock);
			return NULL;
		}

		fdb = fdb->next_hash;
	}

	read_unlock_bh(&br->hash_lock);
	return NULL;
}

void br_fdb_put(struct net_bridge_fdb_entry *ent)
{
	if (atomic_dec_and_test(&ent->use_count))
		kfree(ent);
}

int br_fdb_get_entries(struct net_bridge *br,
		       unsigned char *_buf,
		       int maxnum,
		       int offset)
{
	int i;
	int num;
	struct __fdb_entry *walk;

	num = 0;
	walk = (struct __fdb_entry *)_buf;

	read_lock_bh(&br->hash_lock);
	for (i=0;i<BR_HASH_SIZE;i++) {
		struct net_bridge_fdb_entry *f;

		f = br->hash[i];
		while (f != NULL && num < maxnum) {
			struct __fdb_entry ent;
			int err;
			struct net_bridge_fdb_entry *g;
			struct net_bridge_fdb_entry **pp; 

			if (has_expired(br, f)) {
				f = f->next_hash;
				continue;
			}

			if (offset) {
				offset--;
				f = f->next_hash;
				continue;
			}

			copy_fdb(&ent, f);

			atomic_inc(&f->use_count);
			read_unlock_bh(&br->hash_lock);
			err = copy_to_user(walk, &ent, sizeof(struct __fdb_entry));
			read_lock_bh(&br->hash_lock);

			g = f->next_hash;
			pp = f->pprev_hash;
			br_fdb_put(f);

			if (err)
				goto out_fault;

			if (g == NULL && pp == NULL)
				goto out_disappeared;

			num++;
			walk++;

			f = g;
		}
	}

 out:
	read_unlock_bh(&br->hash_lock);
	return num;

 out_disappeared:
	num = -EAGAIN;
	goto out;

 out_fault:
	num = -EFAULT;
	goto out;
}

static __inline__ void __fdb_possibly_replace(struct net_bridge_fdb_entry *fdb,
					      struct net_bridge_port *source,
					      int is_local)
{
	if (!fdb->is_static || is_local) {
		fdb->dst = source;
		fdb->is_local = is_local;
		fdb->is_static = is_local;
		fdb->ageing_timer = jiffies;
	}
}

void br_fdb_insert(struct net_bridge *br,
		   struct net_bridge_port *source,
		   unsigned char *addr,
		   int is_local)
{
	struct net_bridge_fdb_entry *fdb;
	int hash;

	hash = br_mac_hash(addr);

	write_lock_bh(&br->hash_lock);
	fdb = br->hash[hash];
	while (fdb != NULL) {
		if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
			__fdb_possibly_replace(fdb, source, is_local);
			write_unlock_bh(&br->hash_lock);
			return;
		}

		fdb = fdb->next_hash;
	}

	fdb = kmalloc(sizeof(*fdb), GFP_ATOMIC);
	if (fdb == NULL) {
		write_unlock_bh(&br->hash_lock);
		return;
	}

	memcpy(fdb->addr.addr, addr, ETH_ALEN);
	atomic_set(&fdb->use_count, 1);
	fdb->dst = source;
	fdb->is_local = is_local;
	fdb->is_static = is_local;
	fdb->ageing_timer = jiffies;

	__hash_link(br, fdb, hash);

	write_unlock_bh(&br->hash_lock);
}
