/*      $NetBSD: bridgestp.c,v 1.27 2024/07/05 04:31:53 rin Exp $       */

/*
 * 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
 */

/*
 * 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: bridgestp.c,v 1.27 2024/07/05 04:31:53 rin Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/device.h>
#include <sys/kernel.h>
#include <sys/callout.h>

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

#include <net/if_ether.h>
#include <net/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 */
} __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 */
} __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 *);
static int bstp_root_bridge(struct bridge_softc *sc);
static int bstp_supersedes_port_info(struct bridge_softc *,
                                     struct bridge_iflist *,
                                     struct bstp_config_unit *);
static int bstp_designated_port(struct bridge_softc *, struct bridge_iflist *);
static int bstp_designated_for_some_port(struct bridge_softc *);
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_root_selection(struct bridge_softc *);
static void bstp_designated_port_selection(struct bridge_softc *);
static void bstp_become_designated_port(struct bridge_softc *,
                                        struct bridge_iflist *);
static void bstp_port_state_selection(struct bridge_softc *);
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_set_port_state(struct bridge_iflist *, uint8_t);
#if 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
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 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_root_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
                bif->bif_config_bpdu.cu_message_age =
                    sc->sc_root_port->bif_message_age_timer.value +
                    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) {
                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;

        KASSERT(BRIDGE_LOCKED(sc));

        ifp = bif->bif_ifp;

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

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

        eh = mtod(m, struct ether_header *);

        m_set_rcvif(m, 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_rootid >> 48);
        bpdu.cbu_bridgeaddr[0] = cu->cu_rootid >> 40;
        bpdu.cbu_bridgeaddr[1] = cu->cu_rootid >> 32;
        bpdu.cbu_bridgeaddr[2] = cu->cu_rootid >> 24;
        bpdu.cbu_bridgeaddr[3] = cu->cu_rootid >> 16;
        bpdu.cbu_bridgeaddr[4] = cu->cu_rootid >> 8;
        bpdu.cbu_bridgeaddr[5] = cu->cu_rootid >> 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);

        memcpy(eh->ether_shost, CLLADDR(ifp->if_sadl), ETHER_ADDR_LEN);
        memcpy(eh->ether_dhost, bstp_etheraddr, ETHER_ADDR_LEN);
        eh->ether_type = htons(sizeof(bpdu));

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

        BRIDGE_UNLOCK(sc);
        bridge_enqueue(sc, ifp, m, 0);
        BRIDGE_LOCK(sc);
}

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

static int
bstp_supersedes_port_info(struct bridge_softc *sc, struct bridge_iflist *bif,
    struct bstp_config_unit *cu)
{
        if (cu->cu_rootid < bif->bif_designated_root)
                return (1);
        if (cu->cu_rootid > bif->bif_designated_root)
                return (0);

        if (cu->cu_root_path_cost < bif->bif_designated_cost)
                return (1);
        if (cu->cu_root_path_cost > bif->bif_designated_cost)
                return (0);

        if (cu->cu_bridge_id < bif->bif_designated_bridge)
                return (1);
        if (cu->cu_bridge_id > bif->bif_designated_bridge)
                return (0);

        if (sc->sc_bridge_id != cu->cu_bridge_id)
                return (1);
        if (cu->cu_port_id <= bif->bif_designated_port)
                return (1);
        return (0);
}

static void
bstp_record_config_information(struct bridge_softc *sc,
    struct bridge_iflist *bif, struct bstp_config_unit *cu)
{
        bif->bif_designated_root = cu->cu_rootid;
        bif->bif_designated_cost = cu->cu_root_path_cost;
        bif->bif_designated_bridge = cu->cu_bridge_id;
        bif->bif_designated_port = cu->cu_port_id;
        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;

        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bstp_designated_port(sc, bif) &&
                    (bif->bif_state != BSTP_IFSTATE_DISABLED))
                        bstp_transmit_config(sc, bif);
        }
}

static int
bstp_designated_port(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        return ((bif->bif_designated_bridge == sc->sc_bridge_id)
            && (bif->bif_designated_port == bif->bif_port_id));
}

static void
bstp_transmit_tcn(struct bridge_softc *sc)
{
        struct bstp_tbpdu bpdu;
        struct bridge_iflist *bif = sc->sc_root_port;
        struct ifnet *ifp;
        struct ether_header *eh;
        struct mbuf *m;

        KASSERT(BRIDGE_LOCKED(sc));

        KASSERT(bif != NULL);
        ifp = bif->bif_ifp;
        if ((ifp->if_flags & IFF_RUNNING) == 0)
                return;

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

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

        eh = mtod(m, struct ether_header *);

        memcpy(eh->ether_shost, CLLADDR(ifp->if_sadl), 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, char *) + sizeof(*eh), &bpdu, sizeof(bpdu));

        BRIDGE_UNLOCK(sc);
        bridge_enqueue(sc, ifp, m, 0);
        BRIDGE_LOCK(sc);
}

static void
bstp_configuration_update(struct bridge_softc *sc)
{
        bstp_root_selection(sc);
        bstp_designated_port_selection(sc);
}

static void
bstp_root_selection(struct bridge_softc *sc)
{
        struct bridge_iflist *root_port = NULL, *bif;

        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bstp_designated_port(sc, bif))
                        continue;
                if (bif->bif_state == BSTP_IFSTATE_DISABLED)
                        continue;
                if (bif->bif_designated_root >= sc->sc_bridge_id)
                        continue;
                if (root_port == NULL)
                        goto set_port;

                if (bif->bif_designated_root < root_port->bif_designated_root)
                        goto set_port;
                if (bif->bif_designated_root > root_port->bif_designated_root)
                        continue;

                if ((bif->bif_designated_cost + bif->bif_path_cost) <
                    (root_port->bif_designated_cost + root_port->bif_path_cost))
                        goto set_port;
                if ((bif->bif_designated_cost + bif->bif_path_cost) >
                    (root_port->bif_designated_cost + root_port->bif_path_cost))
                        continue;

                if (bif->bif_designated_bridge <
                    root_port->bif_designated_bridge)
                        goto set_port;
                if (bif->bif_designated_bridge >
                    root_port->bif_designated_bridge)
                        continue;

                if (bif->bif_designated_port < root_port->bif_designated_port)
                        goto set_port;
                if (bif->bif_designated_port > root_port->bif_designated_port)
                        continue;

                if (bif->bif_port_id >= root_port->bif_port_id)
                        continue;
set_port:
                root_port = bif;
        }

        sc->sc_root_port = root_port;
        if (root_port == NULL) {
                sc->sc_designated_root = sc->sc_bridge_id;
                sc->sc_root_path_cost = 0;
        } else {
                sc->sc_designated_root = root_port->bif_designated_root;
                sc->sc_root_path_cost = root_port->bif_designated_cost +
                    root_port->bif_path_cost;
        }
}

static void
bstp_designated_port_selection(struct bridge_softc *sc)
{
        struct bridge_iflist *bif;

        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bstp_designated_port(sc, bif))
                        goto designated;
                if (bif->bif_designated_root != sc->sc_designated_root)
                        goto designated;

                if (sc->sc_root_path_cost < bif->bif_designated_cost)
                        goto designated;
                if (sc->sc_root_path_cost > bif->bif_designated_cost)
                        continue;

                if (sc->sc_bridge_id < bif->bif_designated_bridge)
                        goto designated;
                if (sc->sc_bridge_id > bif->bif_designated_bridge)
                        continue;

                if (bif->bif_port_id > bif->bif_designated_port)
                        continue;
designated:
                bstp_become_designated_port(sc, bif);
        }
}

static void
bstp_become_designated_port(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        bif->bif_designated_root = sc->sc_designated_root;
        bif->bif_designated_cost = sc->sc_root_path_cost;
        bif->bif_designated_bridge = sc->sc_bridge_id;
        bif->bif_designated_port = bif->bif_port_id;
}

static void
bstp_port_state_selection(struct bridge_softc *sc)
{
        struct bridge_iflist *bif;

        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bif == sc->sc_root_port) {
                        bif->bif_config_pending = 0;
                        bif->bif_topology_change_acknowledge = 0;
                        bstp_make_forwarding(sc, bif);
                } else if (bstp_designated_port(sc, bif)) {
                        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);
                }
        }
}

static void
bstp_make_forwarding(struct bridge_softc *sc,
    struct bridge_iflist *bif)
{
        if (bif->bif_state == BSTP_IFSTATE_BLOCKING) {
                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)) {
                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);
                bstp_timer_stop(&bif->bif_forward_delay_timer);
        }
}

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;

        eh = mtod(m, struct ether_header *);

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

        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, void *), 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;

                BRIDGE_LOCK(sc);
                bstp_received_tcn_bpdu(sc, bif, &tu);
                BRIDGE_UNLOCK(sc);

                break;
        case BSTP_MSGTYPE_CFG:
                if (m->m_len < sizeof(cpdu) &&
                    (m = m_pullup(m, sizeof(cpdu))) == NULL)
                        goto out;
                memcpy(&cpdu, mtod(m, void *), 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;

                BRIDGE_LOCK(sc);
                bstp_received_config_bpdu(sc, bif, &cu);
                BRIDGE_UNLOCK(sc);

                break;
        default:
                goto out;
        }

 out:
        m_freem(m);
        return;
}

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

        root = bstp_root_bridge(sc);

        if (bif->bif_state != BSTP_IFSTATE_DISABLED) {
                if (bstp_supersedes_port_info(sc, bif, cu)) {
                        bstp_record_config_information(sc, bif, cu);
                        bstp_configuration_update(sc);
                        bstp_port_state_selection(sc);

                        if ((bstp_root_bridge(sc) == 0) && root) {
                                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 (bif == sc->sc_root_port) {
                                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 (bstp_designated_port(sc, bif))
                        bstp_transmit_config(sc, bif);
        }
}

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 &&
            bstp_designated_port(sc, bif)) {
                bstp_topology_change_detection(sc);
                bstp_acknowledge_topology_change(sc, bif);
        }
}

static void
bstp_hello_timer_expiry(struct bridge_softc *sc)
{
        bstp_config_bpdu_generation(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 root;

        root = bstp_root_bridge(sc);
        bstp_become_designated_port(sc, bif);
        bstp_configuration_update(sc);
        bstp_port_state_selection(sc);

        if ((bstp_root_bridge(sc)) && (root == 0)) {
                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 (bstp_designated_for_some_port(sc) &&
                    bif->bif_change_detection_enabled)
                        bstp_topology_change_detection(sc);
        }
}

static int
bstp_designated_for_some_port(struct bridge_softc *sc)
{

        struct bridge_iflist *bif;

        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bif->bif_designated_bridge == sc->sc_bridge_id)
                        return (1);
        }
        return (0);
}

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);
}

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

        mif = NULL;

        BRIDGE_LOCK(sc);

        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bif->bif_ifp->if_type != IFT_ETHER)
                        continue;
                bif->bif_port_id = (bif->bif_priority << 8) |
                    (bif->bif_ifp->if_index & 0xff);

                if (mif == NULL) {
                        mif = bif;
                        continue;
                }
                if (memcmp(CLLADDR(bif->bif_ifp->if_sadl),
                    CLLADDR(mif->bif_ifp->if_sadl), ETHER_ADDR_LEN) < 0) {
                        mif = bif;
                        continue;
                }
        }

        if (mif == NULL) {
                BRIDGE_UNLOCK(sc);
                bstp_stop(sc);
                return;
        }

        sc->sc_bridge_id =
            (((uint64_t)sc->sc_bridge_priority) << 48) |
            (((uint64_t)(uint8_t)CLLADDR(mif->bif_ifp->if_sadl)[0]) << 40) |
            (((uint64_t)(uint8_t)CLLADDR(mif->bif_ifp->if_sadl)[1]) << 32) |
            (((uint64_t)(uint8_t)CLLADDR(mif->bif_ifp->if_sadl)[2]) << 24) |
            (((uint64_t)(uint8_t)CLLADDR(mif->bif_ifp->if_sadl)[3]) << 16) |
            (((uint64_t)(uint8_t)CLLADDR(mif->bif_ifp->if_sadl)[4]) << 8) |
            (((uint64_t)(uint8_t)CLLADDR(mif->bif_ifp->if_sadl)[5]) << 0);

        BRIDGE_UNLOCK(sc);

        sc->sc_designated_root = sc->sc_bridge_id;
        sc->sc_root_path_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);

        BRIDGE_LOCK(sc);

        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                if (bif->bif_flags & IFBIF_STP)
                        bstp_enable_port(sc, bif);
                else
                        bstp_disable_port(sc, bif);
        }

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

        BRIDGE_UNLOCK(sc);
}

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

        BRIDGE_LOCK(sc);
        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                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);
        }
        BRIDGE_UNLOCK(sc);

        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);

}

static void
bstp_initialize_port(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        bstp_become_designated_port(sc, bif);
        bstp_set_port_state(bif, BSTP_IFSTATE_BLOCKING);
        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);
}

static void
bstp_enable_port(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        bstp_initialize_port(sc, bif);
        bstp_port_state_selection(sc);
}

static void
bstp_disable_port(struct bridge_softc *sc, struct bridge_iflist *bif)
{
        int root;

        root = bstp_root_bridge(sc);
        bstp_become_designated_port(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_configuration_update(sc);
        bstp_port_state_selection(sc);

        if (bstp_root_bridge(sc) && (root == 0)) {
                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);
        }
}

#if notused
static void
bstp_set_bridge_priority(struct bridge_softc *sc, uint64_t new_bridge_id)
{
        struct bridge_iflist *bif;
        int root;

        root = bstp_root_bridge(sc);

        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                if ((bif->bif_flags & IFBIF_STP) == 0)
                        continue;
                if (bstp_designated_port(sc, bif))
                        bif->bif_designated_bridge = new_bridge_id;
        }

        sc->sc_bridge_id = new_bridge_id;

        bstp_configuration_update(sc);
        bstp_port_state_selection(sc);

        if (bstp_root_bridge(sc) && (root == 0)) {
                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_set_port_priority(struct bridge_softc *sc, struct bridge_iflist *bif,
    uint16_t new_port_id)
{
        if (bstp_designated_port(sc, bif))
                bif->bif_designated_port = new_port_id;

        bif->bif_port_id = new_port_id;

        if ((sc->sc_bridge_id == bif->bif_designated_bridge) &&
            (bif->bif_port_id < bif->bif_designated_port)) {
                bstp_become_designated_port(sc, bif);
                bstp_port_state_selection(sc);
        }
}

static void
bstp_set_path_cost(struct bridge_softc *sc, struct bridge_iflist *bif,
    uint32_t path_cost)
{
        bif->bif_path_cost = path_cost;
        bstp_configuration_update(sc);
        bstp_port_state_selection(sc);
}
#endif

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

        if (ifp->if_flags & IFF_UP) {
                switch (ifp->if_link_state) {
                case LINK_STATE_UNKNOWN:
                        /*
                         * Just enable the port if the link state is
                         * unknown.
                         */
                        if (bif->bif_state == BSTP_IFSTATE_DISABLED)
                                bstp_enable_port(sc, bif);
                        break;

                case LINK_STATE_UP:
                        if (bif->bif_state == BSTP_IFSTATE_DISABLED)
                                bstp_enable_port(sc, bif);
                        break;

                case LINK_STATE_DOWN:
                        if (bif->bif_state != BSTP_IFSTATE_DISABLED)
                                bstp_disable_port(sc, bif);
                        break;
                }
                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 bridge_iflist *bif;

        BRIDGE_LOCK(sc);

        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                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);

        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                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);
        }

        BRIDGE_IFLIST_WRITER_FOREACH(bif, sc) {
                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 (sc->sc_if.if_flags & IFF_RUNNING)
                callout_reset(&sc->sc_bstpcallout, hz, bstp_tick, sc);

        BRIDGE_UNLOCK(sc);
}

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);

}