/*
 * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
 * 
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 * $DragonFly: src/usr.sbin/vknetd/mac.c,v 1.1 2008/05/27 01:58:01 dillon Exp $
 */
/*
 * Bridging code (serialized)
 */
#include "vknetd.h"

static struct mac_list LRUList = TAILQ_HEAD_INITIALIZER(LRUList);
static mac_t MacHash[MAC_HSIZE];

void
mac_init(void)
{
        static struct mac MacAry[NMACS];
        int i;

        for (i = 0; i < NMACS; ++i)
                TAILQ_INSERT_TAIL(&LRUList, &MacAry[i], lru_entry);
}

static __inline int
machash(u_int8_t *macbuf)
{
        int hv;

        hv = macbuf[0] ^ (macbuf[1] << 1) ^ (macbuf[2] << 2) ^
             (macbuf[3] << 3) ^ (macbuf[4] << 4) ^ (macbuf[5] << 5);
        return(hv & MAC_HMASK);
}

/*
 * Locate a cached MAC address, return NULL if we do not have it cached.
 * The MAC is moved to the head of the LRU list.
 */
mac_t
mac_find(u_int8_t *macbuf)
{
        mac_t scan;

        for (scan = MacHash[machash(macbuf)]; scan; scan = scan->mac_next) {
                if (bcmp(macbuf, scan->macbuf, 6) == 0) {
                        if (TAILQ_FIRST(&LRUList) != scan) {
                                TAILQ_REMOVE(&LRUList, scan, lru_entry);
                                TAILQ_INSERT_HEAD(&LRUList, scan, lru_entry);
                        }
                        return(scan);
                }
        }
        return(NULL);
}

/*
 * Create a bridge association for a MAC address.  The caller must
 * have already deleted any pre-existing association.
 */
void
mac_add(bridge_t bridge, u_int8_t *macbuf)
{
        mac_t *hashp;
        mac_t mac;

        /*
         * Recycle least recently used MAC
         */
        mac = TAILQ_LAST(&LRUList, mac_list);
        if (mac->bridge)
                mac_delete(mac);

        /*
         * Create the bridge assocation and enter the MAC into the hash
         * table.
         */
        bcopy(macbuf, mac->macbuf, 6);
        TAILQ_INSERT_TAIL(&bridge->mac_list, mac, bridge_entry);

        hashp = &MacHash[machash(mac->macbuf)];
        mac->mac_next = *hashp;
        *hashp = mac;

        mac->bridge = bridge;

        /*
         * We don't want to recycle the MAC any time soon.
         */
        TAILQ_REMOVE(&LRUList, mac, lru_entry);
        TAILQ_INSERT_HEAD(&LRUList, mac, lru_entry);
}

/*
 * Delete a MAC's bridge assocation
 */
void
mac_delete(mac_t mac)
{
        mac_t *hashp;

        /*
         * Remove the bridge linkage
         */
        TAILQ_REMOVE(&mac->bridge->mac_list, mac, bridge_entry);
        mac->bridge = NULL;

        /*
         * Remove the MAC hash linkage
         */
        hashp = &MacHash[machash(mac->macbuf)];
        while (*hashp != mac) {
                assert(*hashp);
                hashp = &(*hashp)->mac_next;
        }
        *hashp = mac->mac_next;

        /*
         * This MAC is now unused, place on end of LRU list.
         */
        TAILQ_REMOVE(&LRUList, mac, lru_entry);
        TAILQ_INSERT_TAIL(&LRUList, mac, lru_entry);
}

/*
 * Return non-zero if this is a broadcast MAC
 */
int
mac_broadcast(u_int8_t *macbuf)
{
        if (macbuf[0] == 0 && macbuf[1] == 0 && macbuf[2] == 0 &&
            macbuf[3] == 0 && macbuf[4] == 0 && macbuf[5] == 0) {
                return(1);
        }
        if (macbuf[0] == 0xFF && macbuf[1] == 0xFF && macbuf[2] == 0xFF &&
            macbuf[3] == 0xFF && macbuf[4] == 0xFF && macbuf[5] == 0xFF) {
                return(1);
        }
        return(0);
}