/*
 * Copyright (c) 2000 Jason L. Wright (jason@thought.net)
 * All rights reserved.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Jason L. Wright
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 *
 * $OpenBSD: bridgestp.c,v 1.5 2001/03/22 03:48:29 jason Exp $
 * $NetBSD: bridgestp.c,v 1.5 2003/11/28 08:56:48 keihan Exp $
 * $FreeBSD: src/sys/net/bridgestp.c,v 1.7 2005/10/11 02:58:32 thompsa Exp $
 */

/*
 * Implementation of the spanning tree protocol as defined in
 * ISO/IEC Final DIS 15802-3 (IEEE P802.1D/D17), May 25, 1998.
 * (In English: IEEE 802.1D, Draft 17, 1998)
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h> /* for M_NOWAIT */
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/kernel.h>
#include <sys/callout.h>
#include <sys/proc.h>
#include <sys/lock.h>
#include <sys/thread.h>
#include <sys/thread2.h>
#include <sys/msgport2.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/if_llc.h>
#include <net/if_media.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/if_ether.h>
#include <net/bridge/if_bridgevar.h>

/* BPDU message types */
#define BSTP_MSGTYPE_CFG        0x00            /* Configuration */
#define BSTP_MSGTYPE_TCN        0x80            /* Topology chg notification */

/* BPDU flags */
#define BSTP_FLAG_TC            0x01            /* Topology change */
#define BSTP_FLAG_TCA           0x80            /* Topology change ack */

#define BSTP_MESSAGE_AGE_INCR   (1 * 256)       /* in 256ths of a second */
#define BSTP_TICK_VAL           (1 * 256)       /* in 256ths of a second */

/*
 * Because BPDU's do not make nicely aligned structures, two different
 * declarations are used: bstp_?bpdu (wire representation, packed) and
 * bstp_*_unit (internal, nicely aligned version).
 */

/* configuration bridge protocol data unit */
struct bstp_cbpdu {
        uint8_t         cbu_dsap;               /* LLC: destination sap */
        uint8_t         cbu_ssap;               /* LLC: source sap */
        uint8_t         cbu_ctl;                /* LLC: control */
        uint16_t        cbu_protoid;            /* protocol id */
        uint8_t         cbu_protover;           /* protocol version */
        uint8_t         cbu_bpdutype;           /* message type */
        uint8_t         cbu_flags;              /* flags (below) */

        /* root id */
        uint16_t        cbu_rootpri;            /* root priority */
        uint8_t cbu_rootaddr[6];        /* root address */

        uint32_t        cbu_rootpathcost;       /* root path cost */

        /* bridge id */
        uint16_t        cbu_bridgepri;          /* bridge priority */
        uint8_t         cbu_bridgeaddr[6];      /* bridge address */

        uint16_t        cbu_portid;             /* port id */
        uint16_t        cbu_messageage;         /* current message age */
        uint16_t        cbu_maxage;             /* maximum age */
        uint16_t        cbu_hellotime;          /* hello time */
        uint16_t        cbu_forwarddelay;       /* forwarding delay */
} __attribute__((__packed__));

/* topology change notification bridge protocol data unit */
struct bstp_tbpdu {
        uint8_t         tbu_dsap;               /* LLC: destination sap */
        uint8_t         tbu_ssap;               /* LLC: source sap */
        uint8_t         tbu_ctl;                /* LLC: control */
        uint16_t        tbu_protoid;            /* protocol id */
        uint8_t         tbu_protover;           /* protocol version */
        uint8_t         tbu_bpdutype;           /* message type */
} __attribute__((__packed__));

const uint8_t bstp_etheraddr[] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };

static void     bstp_initialize_port(struct bridge_softc *,
                    struct bridge_iflist *);
static void     bstp_ifupdstatus(struct bridge_softc *, struct bridge_iflist *);
static void     bstp_enable_port(struct bridge_softc *, struct bridge_iflist *);
static void     bstp_disable_port(struct bridge_softc *,
                    struct bridge_iflist *);
#ifdef notused
static void     bstp_enable_change_detection(struct bridge_iflist *);
static void     bstp_disable_change_detection(struct bridge_iflist *);
#endif /* notused */
static int      bstp_root_bridge(struct bridge_softc *sc);
static void     bstp_transmit_config(struct bridge_softc *,
                    struct bridge_iflist *);
static void     bstp_transmit_tcn(struct bridge_softc *);
static void     bstp_received_config_bpdu(struct bridge_softc *,
                    struct bridge_iflist *, struct bstp_config_unit *);
static void     bstp_received_tcn_bpdu(struct bridge_softc *,
                    struct bridge_iflist *, struct bstp_tcn_unit *);
static void     bstp_record_config_information(struct bridge_softc *,
                    struct bridge_iflist *, struct bstp_config_unit *);
static void     bstp_record_config_timeout_values(struct bridge_softc *,
                    struct bstp_config_unit *);
static void     bstp_config_bpdu_generation(struct bridge_softc *);
static void     bstp_send_config_bpdu(struct bridge_softc *,
                    struct bridge_iflist *, struct bstp_config_unit *);
static void     bstp_configuration_update(struct bridge_softc *);
static void     bstp_port_state_selection(struct bridge_softc *);
static void     bstp_clear_peer_info(struct bridge_softc *,
                    struct bridge_iflist *);
static void     bstp_make_forwarding(struct bridge_softc *,
                    struct bridge_iflist *);
static void     bstp_make_blocking(struct bridge_softc *,
                    struct bridge_iflist *);
static void     bstp_make_l1blocking(struct bridge_softc *sc,
                    struct bridge_iflist *bif);
static void     bstp_adjust_bonded_states(struct bridge_softc *sc,
                    struct bridge_iflist *obif);
static void     bstp_set_port_state(struct bridge_iflist *, uint8_t);
#ifdef notused
static void     bstp_set_bridge_priority(struct bridge_softc *, uint64_t);
static void     bstp_set_port_priority(struct bridge_softc *,
                    struct bridge_iflist *, uint16_t);
static void     bstp_set_path_cost(struct bridge_softc *,
                    struct bridge_iflist *, uint32_t);
#endif /* notused */
static void     bstp_topology_change_detection(struct bridge_softc *);
static void     bstp_topology_change_acknowledged(struct bridge_softc *);
static void     bstp_acknowledge_topology_change(struct bridge_softc *,
                    struct bridge_iflist *);

static void     bstp_tick(void *);
static void     bstp_timer_start(struct bridge_timer *, uint16_t);
static void     bstp_timer_stop(struct bridge_timer *);
static int      bstp_timer_expired(struct bridge_timer *, uint16_t);

static void     bstp_hold_timer_expiry(struct bridge_softc *,
                    struct bridge_iflist *);
static void     bstp_message_age_timer_expiry(struct bridge_softc *,
                    struct bridge_iflist *);
static void     bstp_forward_delay_timer_expiry(struct bridge_softc *,
                    struct bridge_iflist *);
static void     bstp_topology_change_timer_expiry(struct bridge_softc *);
static void     bstp_tcn_timer_expiry(struct bridge_softc *);
static void     bstp_hello_timer_expiry(struct bridge_softc *);
static int      bstp_addr_cmp(const uint8_t *, const uint8_t *);

/*
 * When transmitting a config we tack on our path cost to
 * our aggregated path-to-root cost.
 *
 * Note that sc_designated_cost is the lowest root path cost from all
 * incoming links.  When one is talking about two bridges with multiple
 * links between them the root path cost the secondary bridge transmits
 * will be the lowest root path cost it received across those three
 * links and NOT necessarily the root path cost it received specifically
 * on that particular link.  The receiving end must still add its local
 * link cost back in for differentiation purposes.
 */
static void
bstp_transmit_config(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        if (bif->bif_hold_timer.active) {
                bif->bif_config_pending = 1;
                return;
        }

        bif->bif_config_bpdu.cu_message_type = BSTP_MSGTYPE_CFG;
        bif->bif_config_bpdu.cu_rootid = sc->sc_designated_root;
        bif->bif_config_bpdu.cu_root_path_cost = sc->sc_designated_cost +
                                                 bif->bif_path_cost;
        bif->bif_config_bpdu.cu_bridge_id = sc->sc_bridge_id;
        bif->bif_config_bpdu.cu_port_id = bif->bif_port_id;

        if (bstp_root_bridge(sc)) {
                bif->bif_config_bpdu.cu_message_age = 0;
        } else if (sc->sc_root_port) {
                bif->bif_config_bpdu.cu_message_age =
                        sc->sc_root_port->bif_message_age_timer.value +
                        BSTP_MESSAGE_AGE_INCR;
        } else {
                bif->bif_config_bpdu.cu_message_age = BSTP_MESSAGE_AGE_INCR;
        }

        bif->bif_config_bpdu.cu_max_age = sc->sc_max_age;
        bif->bif_config_bpdu.cu_hello_time = sc->sc_hello_time;
        bif->bif_config_bpdu.cu_forward_delay = sc->sc_forward_delay;
        bif->bif_config_bpdu.cu_topology_change_acknowledgment
            = bif->bif_topology_change_acknowledge;
        bif->bif_config_bpdu.cu_topology_change = sc->sc_topology_change;

        if (bif->bif_config_bpdu.cu_message_age < sc->sc_max_age ||
            (sc->sc_ifp->if_flags & IFF_LINK1)) {
                bif->bif_topology_change_acknowledge = 0;
                bif->bif_config_pending = 0;
                bstp_send_config_bpdu(sc, bif, &bif->bif_config_bpdu);
                bstp_timer_start(&bif->bif_hold_timer, 0);
        }
}

static void
bstp_send_config_bpdu(struct bridge_softc *sc, struct bridge_iflist *bif,
                      struct bstp_config_unit *cu)
{
        struct ifnet *ifp;
        struct mbuf *m;
        struct ether_header *eh;
        struct bstp_cbpdu bpdu;

        ifp = bif->bif_ifp;

        if ((ifp->if_flags & IFF_RUNNING) == 0)
                return;

        MGETHDR(m, M_NOWAIT, MT_DATA);
        if (m == NULL)
                return;

        eh = mtod(m, struct ether_header *);

        m->m_pkthdr.rcvif = ifp;
        m->m_pkthdr.len = sizeof(*eh) + sizeof(bpdu);
        m->m_len = m->m_pkthdr.len;

        bpdu.cbu_ssap = bpdu.cbu_dsap = LLC_8021D_LSAP;
        bpdu.cbu_ctl = LLC_UI;
        bpdu.cbu_protoid = htons(0);
        bpdu.cbu_protover = 0;
        bpdu.cbu_bpdutype = cu->cu_message_type;
        bpdu.cbu_flags = (cu->cu_topology_change ? BSTP_FLAG_TC : 0) |
            (cu->cu_topology_change_acknowledgment ? BSTP_FLAG_TCA : 0);

        bpdu.cbu_rootpri = htons(cu->cu_rootid >> 48);
        bpdu.cbu_rootaddr[0] = cu->cu_rootid >> 40;
        bpdu.cbu_rootaddr[1] = cu->cu_rootid >> 32;
        bpdu.cbu_rootaddr[2] = cu->cu_rootid >> 24;
        bpdu.cbu_rootaddr[3] = cu->cu_rootid >> 16;
        bpdu.cbu_rootaddr[4] = cu->cu_rootid >> 8;
        bpdu.cbu_rootaddr[5] = cu->cu_rootid >> 0;

        bpdu.cbu_rootpathcost = htonl(cu->cu_root_path_cost);

        bpdu.cbu_bridgepri = htons(cu->cu_bridge_id >> 48);
        bpdu.cbu_bridgeaddr[0] = cu->cu_bridge_id >> 40;
        bpdu.cbu_bridgeaddr[1] = cu->cu_bridge_id >> 32;
        bpdu.cbu_bridgeaddr[2] = cu->cu_bridge_id >> 24;
        bpdu.cbu_bridgeaddr[3] = cu->cu_bridge_id >> 16;
        bpdu.cbu_bridgeaddr[4] = cu->cu_bridge_id >> 8;
        bpdu.cbu_bridgeaddr[5] = cu->cu_bridge_id >> 0;

        bpdu.cbu_portid = htons(cu->cu_port_id);
        bpdu.cbu_messageage = htons(cu->cu_message_age);
        bpdu.cbu_maxage = htons(cu->cu_max_age);
        bpdu.cbu_hellotime = htons(cu->cu_hello_time);
        bpdu.cbu_forwarddelay = htons(cu->cu_forward_delay);

        /*
         * Packets sent from the bridge always use the bridge MAC
         * as the source.
         */
        memcpy(eh->ether_shost, IF_LLADDR(sc->sc_ifp), ETHER_ADDR_LEN);
        memcpy(eh->ether_dhost, bstp_etheraddr, ETHER_ADDR_LEN);
        eh->ether_type = htons(sizeof(bpdu));

        memcpy(mtod(m, caddr_t) + sizeof(*eh), &bpdu, sizeof(bpdu));

        bridge_enqueue(ifp, m);
}

static int
bstp_root_bridge(struct bridge_softc *sc)
{
        return (sc->sc_designated_root == sc->sc_bridge_id);
}

/*
 * Returns TRUE if the recorded information from our peer has a shorter
 * graph distance than our current best.
 */
int
bstp_supersedes_port_info(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        if (bif->bif_peer_root < sc->sc_designated_root)
                return (1);
        if (bif->bif_peer_root > sc->sc_designated_root)
                return (0);

        /*
         * bif_peer_cost and sc_designated_cost do not include the local
         * bif_path_cost, otherwise we would not be able to make this
         * comparison.
         */
        if (bif->bif_peer_cost < sc->sc_designated_cost)
                return (1);
        if (bif->bif_peer_cost > sc->sc_designated_cost)
                return (0);

        /*
         * When the peer costs match we have to check the local path
         * cost against the selected root port.  sc_designated_cost
         * in an aggregation and cannot be used.
         */
        if (sc->sc_root_port &&
            bif->bif_path_cost < sc->sc_root_port->bif_path_cost)
                return (1);
        if (sc->sc_root_port &&
            bif->bif_path_cost > sc->sc_root_port->bif_path_cost)
                return (0);

        /*
         * If the path costs are identical the bridge with the lowest
         * bridge_id wins.
         */
        if (bif->bif_peer_bridge < sc->sc_designated_bridge)
                return (1);
        if (bif->bif_peer_bridge > sc->sc_designated_bridge)
                return (0);

        /*
         * bridge_id or bridge+port collision w/peer returns TRUE.
         *
         * This case can also occur when two bridges are connected
         * via multiple links whos path costs have not been set.
         */
        if (bif->bif_peer_bridge != sc->sc_bridge_id)
                return (1);
        if (bif->bif_peer_port <= sc->sc_designated_port)
                return (1);
        return (0);
}

/*
 * The shorter graph distance represented by cu (most of which is also
 * already stored in our bif_peer_* fields) becomes the designated info.
 *
 * NOTE: sc_designated_cost does not include bif_path_cost, it is added
 *       in later on a port-by-port basis as needed.
 */
static void
bstp_record_config_information(struct bridge_softc *sc,
                               struct bridge_iflist *bif,
                               struct bstp_config_unit *cu)
{
        sc->sc_designated_root = bif->bif_peer_root;
        sc->sc_designated_cost = bif->bif_peer_cost;
        sc->sc_designated_bridge = bif->bif_peer_bridge;
        sc->sc_designated_port = bif->bif_peer_port;
        bstp_timer_start(&bif->bif_message_age_timer, cu->cu_message_age);
}

static void
bstp_record_config_timeout_values(struct bridge_softc *sc,
                                  struct bstp_config_unit *config)
{
        sc->sc_max_age = config->cu_max_age;
        sc->sc_hello_time = config->cu_hello_time;
        sc->sc_forward_delay = config->cu_forward_delay;
        sc->sc_topology_change = config->cu_topology_change;
}

static void
bstp_config_bpdu_generation(struct bridge_softc *sc)
{
        struct bridge_iflist *bif, *nbif;

        TAILQ_FOREACH_MUTABLE(bif, &sc->sc_iflists[mycpuid], bif_next, nbif) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bif->bif_state != BSTP_IFSTATE_DISABLED &&
                    ((sc->sc_ifp->if_flags & IFF_LINK1) ||
                     (bif->bif_flags & IFBIF_DESIGNATED))) {
                        bstp_transmit_config(sc, bif);
                }

                if (nbif != NULL && !nbif->bif_onlist) {
                        KKASSERT(bif->bif_onlist);
                        nbif = TAILQ_NEXT(bif, bif_next);
                }
        }
}

static void
bstp_transmit_tcn(struct bridge_softc *sc)
{
        struct bstp_tbpdu bpdu;
        struct ifnet *ifp;
        struct ether_header *eh;
        struct mbuf *m;

        if (sc->sc_root_port == NULL)   /* all iterfaces disabled */
                return;

        ifp = sc->sc_root_port->bif_ifp;
        if ((ifp->if_flags & IFF_RUNNING) == 0)
                return;

        MGETHDR(m, M_NOWAIT, MT_DATA);
        if (m == NULL)
                return;

        m->m_pkthdr.rcvif = ifp;
        m->m_pkthdr.len = sizeof(*eh) + sizeof(bpdu);
        m->m_len = m->m_pkthdr.len;

        eh = mtod(m, struct ether_header *);

        /*
         * Packets sent from the bridge always use the bridge MAC
         * as the source.
         */
        memcpy(eh->ether_shost, IF_LLADDR(sc->sc_ifp), ETHER_ADDR_LEN);
        memcpy(eh->ether_dhost, bstp_etheraddr, ETHER_ADDR_LEN);
        eh->ether_type = htons(sizeof(bpdu));

        bpdu.tbu_ssap = bpdu.tbu_dsap = LLC_8021D_LSAP;
        bpdu.tbu_ctl = LLC_UI;
        bpdu.tbu_protoid = 0;
        bpdu.tbu_protover = 0;
        bpdu.tbu_bpdutype = BSTP_MSGTYPE_TCN;

        memcpy(mtod(m, caddr_t) + sizeof(*eh), &bpdu, sizeof(bpdu));

        bridge_enqueue(ifp, m);
}

/*
 * Recalculate sc->sc_designated* and sc->sc_root_port (if our bridge
 * is calculated to be the root bridge).  We do this by initializing
 * the designated variables to point at us and then scan our peers.
 * Any uninitialized peers will have a max-value root.
 *
 * Clear IFBIF_DESIGNATED on any ports which no longer match the criteria
 * required to be a designated port.  Only aged out ports and the root
 * port can be designated.
 *
 * If we win we do a second scan to determine which port on our bridge
 * is the best.
 */
static void
bstp_configuration_update(struct bridge_softc *sc)
{
        uint64_t        designated_root = sc->sc_bridge_id;
        uint64_t        designated_bridge = sc->sc_bridge_id;
        uint32_t        designated_cost = 0xFFFFFFFFU;
        uint32_t        designated_root_cost = 0xFFFFFFFFU;
        uint16_t        designated_port = 65535;
        struct bridge_iflist *root_port = NULL;
        struct bridge_iflist *bif;

        /*
         * Resolve information from our peers.  Aged peers will have
         * a maxed bif_peer_root and not come under consideration.
         */
        TAILQ_FOREACH(bif, &sc->sc_iflists[mycpuid], bif_next) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bif->bif_state == BSTP_IFSTATE_DISABLED ||
                    bif->bif_state == BSTP_IFSTATE_L1BLOCKING) {
                        continue;
                }

                if (bif->bif_peer_root > designated_root)
                        continue;
                if (bif->bif_peer_root < designated_root)
                        goto set_port;

                /*
                 * NOTE: The designated_cost temporary variable already added
                 *       in the path code of the related root port.
                 */
                if (bif->bif_peer_cost + bif->bif_path_cost > designated_cost)
                        continue;
                if (bif->bif_peer_cost + bif->bif_path_cost < designated_cost)
                        goto set_port;

                if (bif->bif_peer_bridge > designated_bridge)
                        continue;
                if (bif->bif_peer_bridge < designated_bridge)
                        goto set_port;

                if (bif->bif_peer_port > designated_port)
                        continue;
                if (bif->bif_peer_port < designated_port)
                        goto set_port;

                /*
                 * Same root, path cost, bridge, and port.  Set the root
                 * only if we do not already have it.
                 */
                if (root_port)
                        continue;

                /*
                 * New root port (from peers)
                 *
                 * NOTE: Temporarily add bif_path_cost into the designated
                 *       cost to reduce complexity in the loop, it will be
                 *       subtracted out when we are done.
                 */
set_port:
                designated_root = bif->bif_peer_root;
                designated_cost = bif->bif_peer_cost + bif->bif_path_cost;
                designated_root_cost = bif->bif_peer_cost;
                designated_bridge = bif->bif_peer_bridge;
                designated_port = bif->bif_peer_port;
                root_port = bif;
        }

        /*
         * root_port will be NULL at the start here if all of our
         * peers are aged or are not as good a root as our bridge would
         * be.  It can also be NULL due to all related links being
         * disabled.
         *
         * If the root winds up being our bridge scan again against local
         * information.  Unconditionally update IFBIF_DESIGNATED.
         */
        TAILQ_FOREACH(bif, &sc->sc_iflists[mycpuid], bif_next) {
                bif->bif_flags &= ~(IFBIF_DESIGNATED | IFBIF_ROOT);
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bif->bif_state == BSTP_IFSTATE_DISABLED ||
                    bif->bif_state == BSTP_IFSTATE_L1BLOCKING) {
                        continue;
                }

                /*
                 * Set DESIGNATED for an aged or unknown peer.
                 */
                if (bif->bif_peer_bridge == 0xFFFFFFFFFFFFFFFFLLU)
                        bif->bif_flags |= IFBIF_DESIGNATED;
                if (designated_root != sc->sc_bridge_id)
                        continue;

                /*
                 * This is only reached if our bridge is the root bridge,
                 * select the root port (IFBIF_DESIGNATED is set at the
                 * end).
                 *
                 * The peer cost will incorporate the peer bridge's best
                 * cost to the root bridge (us), which is NOT necessarily
                 * our path cost, plus the peer bridge's own path cost.
                 * Because of this we must still add in our path cost for
                 * further differentiation.  Because the peer's 'best' cost
                 * is applied to all of its outgoing messages we should
                 * still come to the same conclusion as the peer.
                 */
                if (bif->bif_peer_cost + bif->bif_path_cost > designated_cost)
                        continue;
                if (bif->bif_peer_cost + bif->bif_path_cost < designated_cost)
                        goto set_port2;

                if (bif->bif_port_id > designated_port)
                        continue;
                if (bif->bif_port_id < designated_port)
                        goto set_port2;
                /* degenerate case (possible peer collision w/our key */

                /*
                 * New port.  Since we are the root, the root cost is always
                 * 0.  The peer's cu_root_path_cost does not necessarily
                 * incorporate our peer path cost, but instead incorporates
                 * the lowest path cost to root for the target bridge
                 * when multiple links are present between the two bridges.
                 * Thus for selection purposes we must still add in our
                 * local path cost.
                 */
set_port2:
                designated_cost = bif->bif_peer_cost + bif->bif_path_cost;
                designated_root_cost = 0;
                designated_bridge = sc->sc_bridge_id;
                designated_port = bif->bif_port_id;
                root_port = bif;
        }

        /*
         * Update aggregate information.  The selected root port always
         * becomes a designated port (along with aged ports).  This can
         * either be the port whos peer is closest to the root or it
         * can be one of our ports if our bridge is the root.
         *
         * The root cost we record in sc_designated_root does not include
         * bif_path_cost of the root port, since we may transmit this
         * out of any port we will add the cost back in later on on
         * a per-port basis.
         *
         * root_port can be NULL here (if all links are disabled)
         */
        if (root_port) {
                sc->sc_designated_root = designated_root;
                sc->sc_designated_cost = designated_root_cost;
                sc->sc_designated_bridge = designated_bridge;
                sc->sc_designated_port = designated_port;
                root_port->bif_flags |= IFBIF_DESIGNATED | IFBIF_ROOT;
        } else {
                sc->sc_designated_root = designated_root;
                sc->sc_designated_cost = designated_cost;
                sc->sc_designated_bridge = designated_bridge;
                sc->sc_designated_port = designated_port;
        }
        sc->sc_root_port = root_port;
}

/*
 * Calculate the desired state for each interface link on our bridge.
 *
 * The best port will match against sc->sc_root_port (whether we are root
 * or whether that port is the closest to the root).  We push this port
 * towards a FORWARDING state.
 *
 * Next come designated ports, either aged ports or ports with no peer info
 * (yet), or the peer who is closest to the root. We push this port towards
 * a FORWARDING state as well.
 *
 * Any remaining ports are pushed towards a BLOCKING state.  Both sides of
 * the port (us and our peer) should wind up placing the two ends in this
 * state or bad things happen.
 */
static void
bstp_port_state_selection(struct bridge_softc *sc)
{
        struct bridge_iflist *bif, *nbif;

        TAILQ_FOREACH_MUTABLE(bif, &sc->sc_iflists[mycpuid], bif_next, nbif) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (sc->sc_root_port &&
                    bif->bif_info == sc->sc_root_port->bif_info) {
                        bif->bif_config_pending = 0;
                        bif->bif_topology_change_acknowledge = 0;
                        bstp_make_forwarding(sc, bif);
                } else if (bif->bif_flags & IFBIF_DESIGNATED) {
                        bstp_timer_stop(&bif->bif_message_age_timer);
                        bstp_make_forwarding(sc, bif);
                } else {
                        bif->bif_config_pending = 0;
                        bif->bif_topology_change_acknowledge = 0;
                        bstp_make_blocking(sc, bif);
                }

                if (nbif != NULL && !nbif->bif_onlist) {
                        KKASSERT(bif->bif_onlist);
                        nbif = TAILQ_NEXT(bif, bif_next);
                }
        }
}

/*
 * Clear peer info, effectively makes the port looked aged out.
 * It becomes a designated go-to port.
 */
static void
bstp_clear_peer_info(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        bif->bif_peer_root = 0xFFFFFFFFFFFFFFFFLLU;
        bif->bif_peer_cost = 0xFFFFFFFFU;
        bif->bif_peer_bridge = 0xFFFFFFFFFFFFFFFFLLU;
        bif->bif_peer_port = 0xFFFFU;

        if (bif->bif_state != BSTP_IFSTATE_DISABLED &&
            bif->bif_state != BSTP_IFSTATE_L1BLOCKING) {
                bif->bif_flags |= IFBIF_DESIGNATED;
        }
}

static void
bstp_make_forwarding(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        if (bif->bif_state == BSTP_IFSTATE_BLOCKING ||
            bif->bif_state == BSTP_IFSTATE_BONDED) {
                bstp_set_port_state(bif, BSTP_IFSTATE_LISTENING);
                bstp_timer_start(&bif->bif_forward_delay_timer, 0);
        }
}

static void
bstp_make_blocking(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        if (bif->bif_state != BSTP_IFSTATE_DISABLED &&
            bif->bif_state != BSTP_IFSTATE_BLOCKING &&
            bif->bif_state != BSTP_IFSTATE_BONDED &&
            bif->bif_state != BSTP_IFSTATE_L1BLOCKING) {
                if ((bif->bif_state == BSTP_IFSTATE_FORWARDING) ||
                    (bif->bif_state == BSTP_IFSTATE_LEARNING)) {
                        if (bif->bif_change_detection_enabled) {
                                bstp_topology_change_detection(sc);
                        }
                }
                bstp_set_port_state(bif, BSTP_IFSTATE_BLOCKING);
                bridge_rtdelete(sc, bif->bif_ifp, IFBF_FLUSHDYN);
                bstp_timer_stop(&bif->bif_forward_delay_timer);
                if (sc->sc_ifp->if_flags & IFF_LINK2)
                        bstp_adjust_bonded_states(sc, bif);
        }
}

static void
bstp_make_l1blocking(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        int was_forwarding = (bif->bif_state == BSTP_IFSTATE_FORWARDING);

        switch(bif->bif_state) {
        case BSTP_IFSTATE_LISTENING:
        case BSTP_IFSTATE_LEARNING:
        case BSTP_IFSTATE_FORWARDING:
        case BSTP_IFSTATE_BLOCKING:
        case BSTP_IFSTATE_BONDED:
                bstp_set_port_state(bif, BSTP_IFSTATE_L1BLOCKING);
                bridge_rtdelete(sc, bif->bif_ifp, IFBF_FLUSHDYN);
                bstp_timer_stop(&bif->bif_forward_delay_timer);
                bstp_timer_stop(&bif->bif_link1_timer);
                if (bif->bif_flags & IFBIF_DESIGNATED) {
                        bif->bif_flags &= ~IFBIF_DESIGNATED;
                        bstp_configuration_update(sc);
                        bstp_port_state_selection(sc);
                }
                if (was_forwarding && (sc->sc_ifp->if_flags & IFF_LINK2))
                        bstp_adjust_bonded_states(sc, bif);
                break;
        default:
                break;
        }
}

/*
 * Member (bif) changes to or from a FORWARDING state.  All members in the
 * same bonding group which are in a BLOCKING or BONDED state must be set
 * to either BLOCKING or BONDED based on whether any members in the bonding
 * group remain in the FORWARDING state.
 *
 * Going between the BLOCKING and BONDED states does not require a
 * configuration update.
 */
static void
bstp_adjust_bonded_states(struct bridge_softc *sc, struct bridge_iflist *obif)
{
        struct bridge_iflist *bif;
        int state = BSTP_IFSTATE_BLOCKING;

        TAILQ_FOREACH(bif, &sc->sc_iflists[mycpuid], bif_next) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bif->bif_state != BSTP_IFSTATE_FORWARDING)
                        continue;
                if (memcmp(IF_LLADDR(bif->bif_ifp), IF_LLADDR(obif->bif_ifp),
                           ETHER_ADDR_LEN) != 0) {
                        continue;
                }
                state = BSTP_IFSTATE_BONDED;
                break;
        }
        TAILQ_FOREACH(bif, &sc->sc_iflists[mycpuid], bif_next) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bif->bif_state != BSTP_IFSTATE_BLOCKING &&
                    bif->bif_state != BSTP_IFSTATE_BONDED) {
                        continue;
                }
                if (memcmp(IF_LLADDR(bif->bif_ifp), IF_LLADDR(obif->bif_ifp),
                           ETHER_ADDR_LEN) != 0) {
                        continue;
                }
                if (bif->bif_bond_weight == 0)
                        bif->bif_state = BSTP_IFSTATE_BLOCKING;
                else
                        bif->bif_state = state;
        }
}

static void
bstp_set_port_state(struct bridge_iflist *bif, uint8_t state)
{
        bif->bif_state = state;
}

static void
bstp_topology_change_detection(struct bridge_softc *sc)
{
        if (bstp_root_bridge(sc)) {
                sc->sc_topology_change = 1;
                bstp_timer_start(&sc->sc_topology_change_timer, 0);
        } else if (!sc->sc_topology_change_detected) {
                bstp_transmit_tcn(sc);
                bstp_timer_start(&sc->sc_tcn_timer, 0);
        }
        sc->sc_topology_change_detected = 1;
}

static void
bstp_topology_change_acknowledged(struct bridge_softc *sc)
{
        sc->sc_topology_change_detected = 0;
        bstp_timer_stop(&sc->sc_tcn_timer);
}

static void
bstp_acknowledge_topology_change(struct bridge_softc *sc,
                                 struct bridge_iflist *bif)
{
        bif->bif_topology_change_acknowledge = 1;
        bstp_transmit_config(sc, bif);
}

void
bstp_input(struct bridge_softc *sc, struct bridge_iflist *bif, struct mbuf *m)
{
        struct ether_header *eh;
        struct bstp_tbpdu tpdu;
        struct bstp_cbpdu cpdu;
        struct bstp_config_unit cu;
        struct bstp_tcn_unit tu;
        uint16_t len;

        if ((bif->bif_flags & IFBIF_STP) == 0)
                goto out;

        /*
         * The L1BLOCKING (ping pong failover) test needs to reset the
         * timer if LINK1 is active.
         */
        if (bif->bif_state == BSTP_IFSTATE_L1BLOCKING) {
                bstp_set_port_state(bif, BSTP_IFSTATE_BLOCKING);
                if (sc->sc_ifp->if_flags & IFF_LINK1)
                        bstp_timer_start(&bif->bif_link1_timer, 0);
                bstp_make_forwarding(sc, bif);
        } else if (sc->sc_ifp->if_flags & IFF_LINK1) {
                bstp_timer_start(&bif->bif_link1_timer, 0);
        }

        eh = mtod(m, struct ether_header *);

        len = ntohs(eh->ether_type);
        if (len < sizeof(tpdu))
                goto out;

        m_adj(m, ETHER_HDR_LEN);

        if (m->m_pkthdr.len > len)
                m_adj(m, len - m->m_pkthdr.len);
        if (m->m_len < sizeof(tpdu) &&
            (m = m_pullup(m, sizeof(tpdu))) == NULL)
                goto out;

        memcpy(&tpdu, mtod(m, caddr_t), sizeof(tpdu));

        if (tpdu.tbu_dsap != LLC_8021D_LSAP ||
            tpdu.tbu_ssap != LLC_8021D_LSAP ||
            tpdu.tbu_ctl != LLC_UI)
                goto out;
        if (tpdu.tbu_protoid != 0 || tpdu.tbu_protover != 0)
                goto out;

        switch (tpdu.tbu_bpdutype) {
        case BSTP_MSGTYPE_TCN:
                tu.tu_message_type = tpdu.tbu_bpdutype;
                bstp_received_tcn_bpdu(sc, bif, &tu);
                break;
        case BSTP_MSGTYPE_CFG:
                if (m->m_len < sizeof(cpdu) &&
                    (m = m_pullup(m, sizeof(cpdu))) == NULL)
                        goto out;
                memcpy(&cpdu, mtod(m, caddr_t), sizeof(cpdu));

                cu.cu_rootid =
                    (((uint64_t)ntohs(cpdu.cbu_rootpri)) << 48) |
                    (((uint64_t)cpdu.cbu_rootaddr[0]) << 40) |
                    (((uint64_t)cpdu.cbu_rootaddr[1]) << 32) |
                    (((uint64_t)cpdu.cbu_rootaddr[2]) << 24) |
                    (((uint64_t)cpdu.cbu_rootaddr[3]) << 16) |
                    (((uint64_t)cpdu.cbu_rootaddr[4]) << 8) |
                    (((uint64_t)cpdu.cbu_rootaddr[5]) << 0);

                cu.cu_bridge_id =
                    (((uint64_t)ntohs(cpdu.cbu_bridgepri)) << 48) |
                    (((uint64_t)cpdu.cbu_bridgeaddr[0]) << 40) |
                    (((uint64_t)cpdu.cbu_bridgeaddr[1]) << 32) |
                    (((uint64_t)cpdu.cbu_bridgeaddr[2]) << 24) |
                    (((uint64_t)cpdu.cbu_bridgeaddr[3]) << 16) |
                    (((uint64_t)cpdu.cbu_bridgeaddr[4]) << 8) |
                    (((uint64_t)cpdu.cbu_bridgeaddr[5]) << 0);

                cu.cu_root_path_cost = ntohl(cpdu.cbu_rootpathcost);
                cu.cu_message_age = ntohs(cpdu.cbu_messageage);
                cu.cu_max_age = ntohs(cpdu.cbu_maxage);
                cu.cu_hello_time = ntohs(cpdu.cbu_hellotime);
                cu.cu_forward_delay = ntohs(cpdu.cbu_forwarddelay);
                cu.cu_port_id = ntohs(cpdu.cbu_portid);
                cu.cu_message_type = cpdu.cbu_bpdutype;
                cu.cu_topology_change_acknowledgment =
                    (cpdu.cbu_flags & BSTP_FLAG_TCA) ? 1 : 0;
                cu.cu_topology_change =
                    (cpdu.cbu_flags & BSTP_FLAG_TC) ? 1 : 0;
                bstp_received_config_bpdu(sc, bif, &cu);
                break;
        default:
                goto out;
        }
out:
        if (m)
                m_freem(m);
}

static void
bstp_received_config_bpdu(struct bridge_softc *sc, struct bridge_iflist *bif,
                          struct bstp_config_unit *cu)
{
        int iamroot;

        iamroot = bstp_root_bridge(sc);

        if (bif->bif_state != BSTP_IFSTATE_DISABLED) {
                /*
                 * Record information from peer.  The peer_cost field
                 * does not include the local bif->bif_path_cost, it will
                 * be added in as needed (since it can be modified manually
                 * this way we don't have to worry about fixups).
                 */
                bif->bif_peer_root = cu->cu_rootid;
                bif->bif_peer_cost = cu->cu_root_path_cost;
                bif->bif_peer_bridge = cu->cu_bridge_id;
                bif->bif_peer_port = cu->cu_port_id;

                if (bstp_supersedes_port_info(sc, bif)) {
                        bstp_record_config_information(sc, bif, cu);
                        bstp_configuration_update(sc);
                        bstp_port_state_selection(sc);

                        /*
                         * If our bridge loses its root status (?)
                         *
                         * Hello's (unsolicited CFG packets) are generated
                         * every hello period of LINK1 is set, otherwise
                         * we are no longer the root bridge and must stop
                         * generating unsolicited CFG packets.
                         */
                        if (iamroot && bstp_root_bridge(sc) == 0) {
                                if ((sc->sc_ifp->if_flags & IFF_LINK1) == 0)
                                        bstp_timer_stop(&sc->sc_hello_timer);

                                if (sc->sc_topology_change_detected) {
                                        bstp_timer_stop(
                                            &sc->sc_topology_change_timer);
                                        bstp_transmit_tcn(sc);
                                        bstp_timer_start(&sc->sc_tcn_timer, 0);
                                }
                        }

                        if (sc->sc_root_port &&
                            bif->bif_info == sc->sc_root_port->bif_info) {
                                bstp_record_config_timeout_values(sc, cu);
                                bstp_config_bpdu_generation(sc);

                                if (cu->cu_topology_change_acknowledgment)
                                        bstp_topology_change_acknowledged(sc);
                        }
                } else if (bif->bif_flags & IFBIF_DESIGNATED) {
                        /*
                         * Update designated ports (aged out peers or
                         * the port closest to the root) at a faster pace.
                         *
                         * Clear our designated flag if we aren't marked
                         * as the root port.
                         */
                        bstp_transmit_config(sc, bif);
                        if ((bif->bif_flags & IFBIF_ROOT) == 0) {
                                bif->bif_flags &= ~IFBIF_DESIGNATED;
                                bstp_configuration_update(sc);
                                bstp_port_state_selection(sc);
                        }
                }
        }
}

static void
bstp_received_tcn_bpdu(struct bridge_softc *sc, struct bridge_iflist *bif,
                       struct bstp_tcn_unit *tcn)
{
        if (bif->bif_state != BSTP_IFSTATE_DISABLED &&
            (bif->bif_flags & IFBIF_DESIGNATED)) {
                bstp_topology_change_detection(sc);
                bstp_acknowledge_topology_change(sc, bif);
        }
}

/*
 * link1 forces continuous hello's (the bridge interface must be cycled
 * to start them up), so keep the timer hot if that is the case, otherwise
 * only send HELLO's if we are the root.
 */
static void
bstp_hello_timer_expiry(struct bridge_softc *sc)
{
        bstp_config_bpdu_generation(sc);

        if ((sc->sc_ifp->if_flags & IFF_LINK1) || bstp_root_bridge(sc))
                bstp_timer_start(&sc->sc_hello_timer, 0);
}

static void
bstp_message_age_timer_expiry(struct bridge_softc *sc,
                              struct bridge_iflist *bif)
{
        int iamroot;

        iamroot = bstp_root_bridge(sc);
        bstp_clear_peer_info(sc, bif);
        bstp_configuration_update(sc);
        bstp_port_state_selection(sc);

        /*
         * If we've become the root and were not the root before
         * we have some cleanup to do.  This also occurs if we
         * wind up being completely isolated.
         */
        if (iamroot == 0 && bstp_root_bridge(sc)) {
                sc->sc_max_age = sc->sc_bridge_max_age;
                sc->sc_hello_time = sc->sc_bridge_hello_time;
                sc->sc_forward_delay = sc->sc_bridge_forward_delay;

                bstp_topology_change_detection(sc);
                bstp_timer_stop(&sc->sc_tcn_timer);
                bstp_config_bpdu_generation(sc);
                bstp_timer_start(&sc->sc_hello_timer, 0);
        }
}

static void
bstp_forward_delay_timer_expiry(struct bridge_softc *sc,
                                struct bridge_iflist *bif)
{
        if (bif->bif_state == BSTP_IFSTATE_LISTENING) {
                bstp_set_port_state(bif, BSTP_IFSTATE_LEARNING);
                bstp_timer_start(&bif->bif_forward_delay_timer, 0);
        } else if (bif->bif_state == BSTP_IFSTATE_LEARNING) {
                bstp_set_port_state(bif, BSTP_IFSTATE_FORWARDING);
                if (sc->sc_designated_bridge == sc->sc_bridge_id &&
                    bif->bif_change_detection_enabled) {
                        bstp_topology_change_detection(sc);
                }
                bstp_configuration_update(sc);
                bstp_port_state_selection(sc);
                if (sc->sc_ifp->if_flags & IFF_LINK2)
                        bstp_adjust_bonded_states(sc, bif);
        }
}

static void
bstp_tcn_timer_expiry(struct bridge_softc *sc)
{
        bstp_transmit_tcn(sc);
        bstp_timer_start(&sc->sc_tcn_timer, 0);
}

static void
bstp_topology_change_timer_expiry(struct bridge_softc *sc)
{
        sc->sc_topology_change_detected = 0;
        sc->sc_topology_change = 0;
}

static void
bstp_hold_timer_expiry(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        if (bif->bif_config_pending)
                bstp_transmit_config(sc, bif);
}

/*
 * If no traffic received directly on this port for the specified
 * period with link1 set we go into a special blocking mode to
 * fail-over traffic to another port.
 */
static void
bstp_link1_timer_expiry(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        if (sc->sc_ifp->if_flags & IFF_LINK1)
                bstp_make_l1blocking(sc, bif);
}

static int
bstp_addr_cmp(const uint8_t *a, const uint8_t *b)
{
        int i, d;

        for (i = 0, d = 0; i < ETHER_ADDR_LEN && d == 0; i++) {
                d = ((int)a[i]) - ((int)b[i]);
        }

        return (d);
}

void
bstp_initialization(struct bridge_softc *sc)
{
        struct bridge_iflist *bif, *mif, *nbif;
        u_char *e_addr;

        KKASSERT(&curthread->td_msgport == BRIDGE_CFGPORT);

        /*
         * Figure out our bridge ID, use the lowest-valued MAC.
         * Include the bridge's own random MAC in the calculation.
         */
        mif = NULL;

        TAILQ_FOREACH(bif, &sc->sc_iflists[mycpuid], bif_next) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bif->bif_ifp->if_type != IFT_ETHER)
                        continue;
                if (mif == NULL) {
                        mif = bif;
                        continue;
                }

                bif->bif_port_id = (bif->bif_priority << 8) |
                                   (bif->bif_ifp->if_index & 0xff);
                if (bstp_addr_cmp(IF_LLADDR(bif->bif_ifp),
                                  IF_LLADDR(mif->bif_ifp)) < 0) {
                        mif = bif;
                        continue;
                }
        }
        if (mif == NULL) {
                bstp_stop(sc);
                return;
        }

        if (bstp_addr_cmp(IF_LLADDR(sc->sc_ifp), IF_LLADDR(mif->bif_ifp)) < 0)
                e_addr = IF_LLADDR(sc->sc_ifp);
        else
                e_addr = IF_LLADDR(mif->bif_ifp);

        sc->sc_bridge_id =
            (((uint64_t)sc->sc_bridge_priority) << 48) |
            (((uint64_t)e_addr[0]) << 40) |
            (((uint64_t)e_addr[1]) << 32) |
            (((uint64_t)e_addr[2]) << 24) |
            (((uint64_t)e_addr[3]) << 16) |
            (((uint64_t)e_addr[4]) << 8) |
            (((uint64_t)e_addr[5]));

        /*
         * Remainder of setup.
         */

        sc->sc_designated_root = sc->sc_bridge_id;
        sc->sc_designated_cost = 0;
        sc->sc_root_port = NULL;

        sc->sc_max_age = sc->sc_bridge_max_age;
        sc->sc_hello_time = sc->sc_bridge_hello_time;
        sc->sc_forward_delay = sc->sc_bridge_forward_delay;
        sc->sc_topology_change_detected = 0;
        sc->sc_topology_change = 0;
        bstp_timer_stop(&sc->sc_tcn_timer);
        bstp_timer_stop(&sc->sc_topology_change_timer);

        if (callout_pending(&sc->sc_bstpcallout) == 0)
                callout_reset(&sc->sc_bstpcallout, hz,
                    bstp_tick, sc);

        TAILQ_FOREACH_MUTABLE(bif, &sc->sc_iflists[mycpuid], bif_next, nbif) {
                if (sc->sc_ifp->if_flags & IFF_LINK1)
                        bstp_timer_start(&bif->bif_link1_timer, 0);
                if (bif->bif_flags & IFBIF_STP)
                        bstp_ifupdstatus(sc, bif);
                else
                        bstp_disable_port(sc, bif);

                if (nbif != NULL && !nbif->bif_onlist) {
                        KKASSERT(bif->bif_onlist);
                        nbif = TAILQ_NEXT(bif, bif_next);
                }
        }

        bstp_port_state_selection(sc);
        bstp_config_bpdu_generation(sc);
        bstp_timer_start(&sc->sc_hello_timer, 0);
}

void
bstp_stop(struct bridge_softc *sc)
{
        struct bridge_iflist *bif;

        KKASSERT(&curthread->td_msgport == BRIDGE_CFGPORT);

        TAILQ_FOREACH(bif, &sc->sc_iflists[mycpuid], bif_next) {
                bstp_set_port_state(bif, BSTP_IFSTATE_DISABLED);
                bstp_timer_stop(&bif->bif_hold_timer);
                bstp_timer_stop(&bif->bif_message_age_timer);
                bstp_timer_stop(&bif->bif_forward_delay_timer);
                bstp_timer_stop(&bif->bif_link1_timer);
        }

        callout_stop(&sc->sc_bstpcallout);

        bstp_timer_stop(&sc->sc_topology_change_timer);
        bstp_timer_stop(&sc->sc_tcn_timer);
        bstp_timer_stop(&sc->sc_hello_timer);

        crit_enter();
        lwkt_dropmsg(&sc->sc_bstptimemsg.lmsg);
        crit_exit();
}

/*
 * [re]initialize a port.  The port is initialized to a L1BLOCKING state
 * or a BLOCKING state.  When link ping/pong is enabled (LINK1) we start
 * out in the L1BLOCKING state to prevent flapping from blowing up the
 * state of the other ports.
 *
 * Either way the first config packet received will knock the port into
 * the LISTENING state.
 */
static void
bstp_initialize_port(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        int needs_adjust = (bif->bif_state == BSTP_IFSTATE_FORWARDING ||
                            bif->bif_state == BSTP_IFSTATE_BLOCKING ||
                            bif->bif_state == BSTP_IFSTATE_BONDED);

        if (sc->sc_ifp->if_flags & IFF_LINK1)
                bstp_set_port_state(bif, BSTP_IFSTATE_L1BLOCKING);
        else
                bstp_set_port_state(bif, BSTP_IFSTATE_BLOCKING);
        bstp_clear_peer_info(sc, bif);
        bif->bif_topology_change_acknowledge = 0;
        bif->bif_config_pending = 0;
        bif->bif_change_detection_enabled = 1;
        bstp_timer_stop(&bif->bif_message_age_timer);
        bstp_timer_stop(&bif->bif_forward_delay_timer);
        bstp_timer_stop(&bif->bif_hold_timer);
        bstp_timer_stop(&bif->bif_link1_timer);
        if (needs_adjust && (sc->sc_ifp->if_flags & IFF_LINK2))
                bstp_adjust_bonded_states(sc, bif);
}

/*
 * When enabling a port that was previously disabled no configuration
 * update occurs, otherwise down/up or running/not-running flapping
 * (e.g. by openvpn on a TAP interface) will blow up the other ports.
 */
static void
bstp_enable_port(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        int was_disabled = (bif->bif_state == BSTP_IFSTATE_DISABLED ||
                            bif->bif_state == BSTP_IFSTATE_L1BLOCKING);

        bstp_initialize_port(sc, bif);
        if (sc->sc_ifp->if_flags & IFF_LINK1)
                bstp_timer_start(&bif->bif_link1_timer, 0);
        if (was_disabled == 0) {
                bstp_configuration_update(sc);
                bstp_port_state_selection(sc);
        }
        bstp_adjust_bonded_states(sc, bif);
}

/*
 * When disabling a port that was previously in a non-forwarding or bonded
 * state no configuration update occurs, otherwise down/up or
 * running/not-running flapping (e.g. by openvpn on a TAP interface) will
 * blow up the other ports.
 */
static void
bstp_disable_port(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        int was_forwarding = (bif->bif_state == BSTP_IFSTATE_FORWARDING);
        int was_bonded = (bif->bif_state == BSTP_IFSTATE_BONDED);
        int iamroot;

        iamroot = bstp_root_bridge(sc);

        bstp_clear_peer_info(sc, bif);
        bstp_set_port_state(bif, BSTP_IFSTATE_DISABLED);
        bif->bif_topology_change_acknowledge = 0;
        bif->bif_config_pending = 0;
        bstp_timer_stop(&bif->bif_message_age_timer);
        bstp_timer_stop(&bif->bif_forward_delay_timer);
        bstp_timer_stop(&bif->bif_link1_timer);
        if (was_forwarding || was_bonded) {
                bstp_configuration_update(sc);
                bstp_port_state_selection(sc);
        }
        bridge_rtdelete(sc, bif->bif_ifp, IFBF_FLUSHDYN);
        if (was_forwarding && (sc->sc_ifp->if_flags & IFF_LINK2))
                bstp_adjust_bonded_states(sc, bif);

        if (iamroot == 0 && bstp_root_bridge(sc)) {
                sc->sc_max_age = sc->sc_bridge_max_age;
                sc->sc_hello_time = sc->sc_bridge_hello_time;
                sc->sc_forward_delay = sc->sc_bridge_forward_delay;

                bstp_topology_change_detection(sc);
                bstp_timer_stop(&sc->sc_tcn_timer);
                bstp_config_bpdu_generation(sc);
                bstp_timer_start(&sc->sc_hello_timer, 0);
        }
}

void
bstp_linkstate(struct ifnet *ifp, int state)
{
        struct bridge_softc *sc;
        struct bridge_iflist *bif;

        sc = ifp->if_bridge;
        ifnet_serialize_all(sc->sc_ifp);

        /*
         * bstp_ifupdstatus() may block, but it is the last
         * operation of the member iface iteration, so we
         * don't need to use LIST_FOREACH_MUTABLE()+bif_onlist
         * check here.
         */
        TAILQ_FOREACH(bif, &sc->sc_iflists[mycpuid], bif_next) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;

                if (bif->bif_ifp == ifp) {
                        bstp_ifupdstatus(sc, bif);
                        break;
                }
        }
        ifnet_deserialize_all(sc->sc_ifp);
}

static void
bstp_ifupdstatus(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        struct ifnet *ifp = bif->bif_ifp;
        struct ifmediareq ifmr;
        int error = 0;

        bzero((char *)&ifmr, sizeof(ifmr));
        ifnet_serialize_all(ifp);
        error = (*ifp->if_ioctl)(ifp, SIOCGIFMEDIA, (caddr_t)&ifmr, NULL);
        ifnet_deserialize_all(ifp);

        if ((error == 0) && (ifp->if_flags & IFF_UP)) {
                if (ifmr.ifm_status & IFM_ACTIVE) {
                        if (bif->bif_state == BSTP_IFSTATE_DISABLED)
                                bstp_enable_port(sc, bif);

                } else {
                        if (bif->bif_state != BSTP_IFSTATE_DISABLED)
                                bstp_disable_port(sc, bif);
                }
                return;
        }

        if (bif->bif_state != BSTP_IFSTATE_DISABLED)
                bstp_disable_port(sc, bif);
}

static void
bstp_tick(void *arg)
{
        struct bridge_softc *sc = arg;
        struct lwkt_msg *lmsg;

        KKASSERT(mycpuid == BRIDGE_CFGCPU);

        crit_enter();

        if (callout_pending(&sc->sc_bstpcallout) ||
            !callout_active(&sc->sc_bstpcallout)) {
                crit_exit();
                return;
        }
        callout_deactivate(&sc->sc_bstpcallout);

        lmsg = &sc->sc_bstptimemsg.lmsg;
        KKASSERT(lmsg->ms_flags & MSGF_DONE);
        lwkt_sendmsg_oncpu(BRIDGE_CFGPORT, lmsg);

        crit_exit();
}

void
bstp_tick_handler(netmsg_t msg)
{
        struct bridge_softc *sc = msg->lmsg.u.ms_resultp;
        struct bridge_iflist *bif;

        KKASSERT(&curthread->td_msgport == BRIDGE_CFGPORT);
        crit_enter();
        /* Reply ASAP */
        lwkt_replymsg(&msg->lmsg, 0);
        crit_exit();

        ifnet_serialize_all(sc->sc_ifp);

        /*
         * NOTE:
         * We don't need to worry that member iface is ripped
         * from the per-cpu list during the blocking operation
         * in the loop body, since deletion is serialized by
         * BRIDGE_CFGPORT
         */

        TAILQ_FOREACH(bif, &sc->sc_iflists[mycpuid], bif_next) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                /*
                 * XXX This can cause a lag in "link does away"
                 * XXX and "spanning tree gets updated".  We need
                 * XXX come sort of callback from the link state
                 * XXX update code to kick spanning tree.
                 * XXX --thorpej@NetBSD.org
                 */
                bstp_ifupdstatus(sc, bif);
        }

        if (bstp_timer_expired(&sc->sc_hello_timer, sc->sc_hello_time))
                bstp_hello_timer_expiry(sc);

        if (bstp_timer_expired(&sc->sc_tcn_timer, sc->sc_bridge_hello_time))
                bstp_tcn_timer_expiry(sc);

        if (bstp_timer_expired(&sc->sc_topology_change_timer,
            sc->sc_topology_change_time))
                bstp_topology_change_timer_expiry(sc);

        TAILQ_FOREACH(bif, &sc->sc_iflists[mycpuid], bif_next) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bstp_timer_expired(&bif->bif_message_age_timer,
                    sc->sc_max_age))
                        bstp_message_age_timer_expiry(sc, bif);
        }

        TAILQ_FOREACH(bif, &sc->sc_iflists[mycpuid], bif_next) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bstp_timer_expired(&bif->bif_forward_delay_timer,
                    sc->sc_forward_delay))
                        bstp_forward_delay_timer_expiry(sc, bif);

                if (bstp_timer_expired(&bif->bif_hold_timer,
                    sc->sc_hold_time))
                        bstp_hold_timer_expiry(sc, bif);

                if (bstp_timer_expired(&bif->bif_link1_timer,
                    sc->sc_hello_time * 10))
                        bstp_link1_timer_expiry(sc, bif);
        }

        if (sc->sc_ifp->if_flags & IFF_RUNNING)
                callout_reset(&sc->sc_bstpcallout, hz, bstp_tick, sc);

        ifnet_deserialize_all(sc->sc_ifp);
}

static void
bstp_timer_start(struct bridge_timer *t, uint16_t v)
{
        t->value = v;
        t->active = 1;
}

static void
bstp_timer_stop(struct bridge_timer *t)
{
        t->value = 0;
        t->active = 0;
}

static int
bstp_timer_expired(struct bridge_timer *t, uint16_t v)
{
        if (t->active == 0)
                return (0);
        t->value += BSTP_TICK_VAL;
        if (t->value >= v) {
                bstp_timer_stop(t);
                return (1);
        }
        return (0);

}