text: /*	$NetBSD: bridgestp.c,v 1.2 2001/11/12 23:49:34 lukem 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 1.2 2001/11/12 23:49:34 lukem 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 */
  } __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 };
  
  void	bstp_initialize_port(struct bridge_softc *, struct bridge_iflist *);
  void	bstp_ifupdstatus(struct bridge_softc *, struct bridge_iflist *);
  void	bstp_enable_port(struct bridge_softc *, struct bridge_iflist *);
  void	bstp_disable_port(struct bridge_softc *, struct bridge_iflist *);
  void	bstp_enable_change_detection(struct bridge_iflist *);
  void	bstp_disable_change_detection(struct bridge_iflist *);
  int	bstp_root_bridge(struct bridge_softc *sc);
  int	bstp_supersedes_port_info(struct bridge_softc *,
  	    struct bridge_iflist *, struct bstp_config_unit *);
  int	bstp_designated_port(struct bridge_softc *, struct bridge_iflist *);
  int	bstp_designated_for_some_port(struct bridge_softc *);
  void	bstp_transmit_config(struct bridge_softc *, struct bridge_iflist *);
  void	bstp_transmit_tcn(struct bridge_softc *);
  void	bstp_received_config_bpdu(struct bridge_softc *,
  	    struct bridge_iflist *, struct bstp_config_unit *);
  void	bstp_received_tcn_bpdu(struct bridge_softc *, struct bridge_iflist *,
  	    struct bstp_tcn_unit *);
  void	bstp_record_config_information(struct bridge_softc *,
  	    struct bridge_iflist *, struct bstp_config_unit *);
  void	bstp_record_config_timeout_values(struct bridge_softc *,
  	    struct bstp_config_unit *);
  void	bstp_config_bpdu_generation(struct bridge_softc *);
  void	bstp_send_config_bpdu(struct bridge_softc *, struct bridge_iflist *,
  	    struct bstp_config_unit *);
  void	bstp_configuration_update(struct bridge_softc *);
  void	bstp_root_selection(struct bridge_softc *);
  void	bstp_designated_port_selection(struct bridge_softc *);
  void	bstp_become_designated_port(struct bridge_softc *,
  	    struct bridge_iflist *);
  void	bstp_port_state_selection(struct bridge_softc *);
  void	bstp_make_forwarding(struct bridge_softc *, struct bridge_iflist *);
  void	bstp_make_blocking(struct bridge_softc *, struct bridge_iflist *);
  void	bstp_set_port_state(struct bridge_iflist *, uint8_t);
  void	bstp_set_bridge_priority(struct bridge_softc *, uint64_t);
  void	bstp_set_port_priority(struct bridge_softc *, struct bridge_iflist *,
  	    uint16_t);
  void	bstp_set_path_cost(struct bridge_softc *, struct bridge_iflist *,
  	    uint32_t);
  void	bstp_topology_change_detection(struct bridge_softc *);
  void	bstp_topology_change_acknowledged(struct bridge_softc *);
  void	bstp_acknowledge_topology_change(struct bridge_softc *,
  	    struct bridge_iflist *);
  
  void	bstp_tick(void *);
  void	bstp_timer_start(struct bridge_timer *, uint16_t);
  void	bstp_timer_stop(struct bridge_timer *);
  int	bstp_timer_expired(struct bridge_timer *, uint16_t);
  
  void	bstp_hold_timer_expiry(struct bridge_softc *, struct bridge_iflist *);
  void	bstp_message_age_timer_expiry(struct bridge_softc *,
  	    struct bridge_iflist *);
  void	bstp_forward_delay_timer_expiry(struct bridge_softc *,
  	    struct bridge_iflist *);
  void	bstp_topology_change_timer_expiry(struct bridge_softc *);
  void	bstp_tcn_timer_expiry(struct bridge_softc *);
  void	bstp_hello_timer_expiry(struct bridge_softc *);
  
  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);
  	}
  }
  
  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;
  	int s;
  
  	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->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_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, LLADDR(ifp->if_sadl), 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));
  
  	s = splnet();
  	bridge_enqueue(sc, ifp, m);
  	splx(s);
  }
  
  int
  bstp_root_bridge(struct bridge_softc *sc)
  {
  	return (sc->sc_designated_root == sc->sc_bridge_id);
  }
  
  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);
  }
  
  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);
  }
  
  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;
  }
  
  void
  bstp_config_bpdu_generation(struct bridge_softc *sc)
  {
  	struct bridge_iflist *bif;
  
  	LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
  		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);
  	}
  }
  
  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));
  }
  
  void
  bstp_transmit_tcn(struct bridge_softc *sc)
  {
  	struct bstp_tbpdu bpdu;
  	struct bridge_iflist *bif = sc->sc_root_port;
  	struct ifnet *ifp = bif->bif_ifp;
  	struct ether_header *eh;
  	struct mbuf *m;
  	int s;
  
  	if ((ifp->if_flags & IFF_RUNNING) == 0)
  		return;
  
  	MGETHDR(m, M_DONTWAIT, 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 *);
  
  	memcpy(eh->ether_shost, LLADDR(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, caddr_t) + sizeof(*eh), &bpdu, sizeof(bpdu));
  
  	s = splnet();
  	bridge_enqueue(sc, ifp, m);
  	splx(s);
  }
  
  void
  bstp_configuration_update(struct bridge_softc *sc)
  {
  	bstp_root_selection(sc);
  	bstp_designated_port_selection(sc);
  }
  
  void
  bstp_root_selection(struct bridge_softc *sc)
  {
  	struct bridge_iflist *root_port = NULL, *bif;
  
  	LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
  		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;
  	}
  }
  
  void
  bstp_designated_port_selection(struct bridge_softc *sc)
  {
  	struct bridge_iflist *bif;
  
  	LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
  		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);
  	}
  }
  
  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;
  }
  
  void
  bstp_port_state_selection(struct bridge_softc *sc)
  {
  	struct bridge_iflist *bif;
  
  	LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
  		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);
  		}
  	}
  }
  
  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);
  	}
  }
  
  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);
  	}
  }
  
  void
  bstp_set_port_state(struct bridge_iflist *bif, uint8_t state)
  {
  	bif->bif_state = state;
  }
  
  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;
  }
  
  void
  bstp_topology_change_acknowledged(struct bridge_softc *sc)
  {
  	sc->sc_topology_change_detected = 0;
  	bstp_timer_stop(&sc->sc_tcn_timer);
  }
  
  void
  bstp_acknowledge_topology_change(struct bridge_softc *sc,
      struct bridge_iflist *bif)
  {
  	bif->bif_topology_change_acknowledge = 1;
  	bstp_transmit_config(sc, bif);
  }
  
  struct mbuf *
  bstp_input(struct ifnet *ifp, struct mbuf *m)
  {
  	struct bridge_softc *sc = ifp->if_bridge;
  	struct bridge_iflist *bif = NULL;
  	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 *);
  
  	LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
  		if ((bif->bif_flags & IFBIF_STP) == 0)
  			continue;
  		if (bif->bif_ifp == ifp)
  			break;
  	}
  	if (bif == NULL)
  		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, 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);
  	return (NULL);
  }
  
  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);
  	}
  }
  
  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);
  	}
  }
  
  void
  bstp_hello_timer_expiry(struct bridge_softc *sc)
  {
  	bstp_config_bpdu_generation(sc);
  	bstp_timer_start(&sc->sc_hello_timer, 0);
  }
  
  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);
  	}
  }
  
  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);
  	}
  }
  
  int
  bstp_designated_for_some_port(struct bridge_softc *sc)
  {
  
  	struct bridge_iflist *bif;
  
  	LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
  		if ((bif->bif_flags & IFBIF_STP) == 0)
  			continue;
  		if (bif->bif_designated_bridge == sc->sc_bridge_id)
  			return (1);
  	}
  	return (0);
  }
  
  void
  bstp_tcn_timer_expiry(struct bridge_softc *sc)
  {
  	bstp_transmit_tcn(sc);
  	bstp_timer_start(&sc->sc_tcn_timer, 0);
  }
  
  void
  bstp_topology_change_timer_expiry(struct bridge_softc *sc)
  {
  	sc->sc_topology_change_detected = 0;
  	sc->sc_topology_change = 0;
  }
  
  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;
  	LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
  		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(LLADDR(bif->bif_ifp->if_sadl),
  		    LLADDR(mif->bif_ifp->if_sadl), ETHER_ADDR_LEN) < 0) {
  			mif = bif;
  			continue;
  		}
  	}
  	if (mif == NULL) {
  		bstp_stop(sc);
  		return;
  	}
  
  	sc->sc_bridge_id =
  	    (((uint64_t)sc->sc_bridge_priority) << 48) |
  	    (((uint64_t)LLADDR(mif->bif_ifp->if_sadl)[0]) << 40) |
  	    (((uint64_t)LLADDR(mif->bif_ifp->if_sadl)[1]) << 32) |
  	    (LLADDR(mif->bif_ifp->if_sadl)[2] << 24) |
  	    (LLADDR(mif->bif_ifp->if_sadl)[3] << 16) |
  	    (LLADDR(mif->bif_ifp->if_sadl)[4] << 8) |
  	    (LLADDR(mif->bif_ifp->if_sadl)[5]);
  
  	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_active(&sc->sc_bstpcallout) == 0)
  		callout_reset(&sc->sc_bstpcallout, hz,
  		    bstp_tick, sc);
  
  	LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
  		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);
  }
  
  void
  bstp_stop(struct bridge_softc *sc)
  {
  	struct bridge_iflist *bif;
  
  	LIST_FOREACH(bif, &sc->sc_iflist, 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);
  	}
  
  	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);
  
  }
  
  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);
  }
  
  void
  bstp_enable_port(struct bridge_softc *sc, struct bridge_iflist *bif)
  {
  	bstp_initialize_port(sc, bif);
  	bstp_port_state_selection(sc);
  }
  
  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);
  	}
  }
  
  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);
  
  	LIST_FOREACH(bif, &sc->sc_iflist, bif_next) {
  		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);
  	}
  }
  
  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);
  	}
  }
  
  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);
  }
  
  void
  bstp_enable_change_detection(struct bridge_iflist *bif)
  {
  	bif->bif_change_detection_enabled = 1;
  }
  
  void
  bstp_disable_change_detection(struct bridge_iflist *bif)
  {
  	bif->bif_change_detection_enabled = 0;
  }
  
  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);
  }
  
  void
  bstp_tick(void *arg)
  {
  	struct bridge_softc *sc = arg;
  	struct bridge_iflist *bif;
  	int s;
  
  	s = splnet();
  
  	LIST_FOREACH(bif, &sc->sc_iflist, 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);
  
  	LIST_FOREACH(bif, &sc->sc_iflist, 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);
  	}
  
  	LIST_FOREACH(bif, &sc->sc_iflist, 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 (sc->sc_if.if_flags & IFF_RUNNING)
  		callout_reset(&sc->sc_bstpcallout, hz, bstp_tick, sc);
  
  	splx(s);
  }
  
  void
  bstp_timer_start(struct bridge_timer *t, uint16_t v)
  {
  	t->value = v;
  	t->active = 1;
  }
  
  void
  bstp_timer_stop(struct bridge_timer *t)
  {
  	t->value = 0;
  	t->active = 0;
  }
  
  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);
  
  }
  