path: root/sys/net/bfd.c

/*	$OpenBSD: bfd.c,v 1.15 2016/09/03 22:51:15 phessler Exp $	*/

/*
 * Copyright (c) 2016 Peter Hessler <phessler@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Support for Bi-directional Forwarding Detection (RFC 5880 / 5881)
 */

#include <sys/errno.h>
#include <sys/param.h>

#include <sys/task.h>
#include <sys/pool.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/stdint.h>
#include <sys/systm.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/ip.h>

#include <net/bfd.h>

/*
 * RFC 5880 Page 7
 * The Mandatory Section of a BFD Control packet has the following
 * format:
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |Vers | Diag    |Sta|P|F|C|A|D|M|  Detect Mult  |    Length     |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                      My Discriminator                         |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                     Your Discriminator                        |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                  Desired Min TX Interval                      |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                 Required Min RX Interval                      |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |                Required Min Echo RX Interval                  |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 *
 * An optional Authentication Section MAY be present:
 *  0                   1                   2                   3
 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 * |   Auth Type   |   Auth Len    |     Authentication Data...    |
 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 *
 */

/* BFD on-wire format */
struct bfd_header {
	u_int8_t	bfd_ver_diag;
	u_int8_t	bfd_sta_flags;

	u_int8_t	bfd_detect_multi;		/* detection time multiplier */
	u_int8_t	bfd_length;			/* in bytes */
	u_int32_t	bfd_my_discriminator;		/* From this system */
	u_int32_t	bfd_your_discriminator;		/* Received */
	u_int32_t	bfd_desired_min_tx_interval;	/* in microseconds */
	u_int32_t	bfd_required_min_rx_interval;	/* in microseconds */
	u_int32_t	bfd_required_min_echo_interval;	/* in microseconds */
} __packed;

/* optional authentication on-wire format */
struct bfd_auth_header {
	u_int8_t	bfd_auth_type;
	u_int8_t	bfd_auth_len;
	u_int16_t	bfd_auth_data;
} __packed;

#define BFD_VERSION		1	/* RFC 5880 Page 6 */
#define BFD_VER(x)		(((x) & 0xe0) >> 5)
#define BFD_DIAG(x)		((x) & 0x1f)
#define BFD_STATE(x)		(((x) & 0xf0) >> 6)
#define BFD_FLAGS(x)		((x) & 0x0f)
#define BFD_HDRLEN		24	/* RFC 5880 Page 37 */
#define BFD_AUTH_SIMPLE_LEN	16 + 3	/* RFC 5880 Page 10 */
#define BFD_AUTH_MD5_LEN	24	/* RFC 5880 Page 11 */
#define BFD_AUTH_SHA1_LEN	28	/* RFC 5880 Page 12 */

#define BFD_MODE_ACTIVE		1
#define BFD_MODE_PASSIVE	2

/* Diagnostic Code (RFC 5880 Page 8) */
#define BFD_DIAG_NONE			0
#define BFD_DIAG_EXPIRED		1
#define BFD_DIAG_ECHO_FAILED		2
#define BFD_DIAG_NEIGHBOR_SIGDOWN	3
#define BFD_DIAG_FIB_RESET		4
#define BFD_DIAG_PATH_DOWN		5
#define BFD_DIAG_CONCAT_PATH_DOWN	6
#define BFD_DIAG_ADMIN_DOWN		7
#define BFD_DIAG_CONCAT_REVERSE_DOWN	8

/* State (RFC 5880 Page 8) */
#define BFD_STATE_ADMINDOWN		0
#define BFD_STATE_DOWN			1
#define BFD_STATE_INIT			2
#define BFD_STATE_UP			3

/* Flags (RFC 5880 Page 8) */
#define BFD_FLAG_P			0x20
#define BFD_FLAG_F			0x10
#define BFD_FLAG_C			0x08
#define BFD_FLAG_A			0x04
#define BFD_FLAG_D			0x02
#define BFD_FLAG_M			0x01


/* Auth Type (RFC 5880 Page 10) */
#define BFD_AUTH_TYPE_RESERVED		0
#define BFD_AUTH_TYPE_SIMPLE		1
#define BFD_AUTH_KEYED_MD5		2
#define BFD_AUTH_METICULOUS_MD5		3
#define BFD_AUTH_KEYED_SHA1		4
#define BFD_AUTH_METICULOUS_SHA1	5

#define BFD_UDP_PORT_CONTROL		3784
#define BFD_UDP_PORT_ECHO		3785

#define BFD_SECOND			1000000 /* 1,000,000 us == 1 second */
/* We cannot handle more often than 10ms, so force a minimum */
#define BFD_MINIMUM			10000	/* 10,000 us == 10 ms */


/* These spellings and capitalizations match RFC 5880 6.8.1*/
/* Do not change */
struct bfd_state {
	u_int32_t	SessionState;
	u_int32_t	RemoteSessionState;
	u_int32_t	LocalDiscr;	/* Unique identifier */
	u_int32_t	RemoteDiscr;	/* Unique identifier */
	u_int32_t	LocalDiag;
	u_int32_t	RemoteDiag;
	u_int32_t	DesiredMinTxInterval;
	u_int32_t	RequiredMinRxInterval;
	u_int32_t	RemoteMinRxInterval;
	u_int32_t	DemandMode;
	u_int32_t	RemoteDemandMode;
	u_int32_t	DetectMult;	/* Detection Time Multiplier*/
	u_int32_t	AuthType;
	u_int32_t	RcvAuthSeq;
	u_int32_t	XmitAuthSeq;
	u_int32_t	AuthSeqKnown;
};

struct pool	 bfd_pool, bfd_pool_peer;
struct taskq	*bfdtq;

struct bfd_softc *bfd_lookup(struct rtentry *);
struct socket	*bfd_listener(struct bfd_softc *, u_int);
struct socket	*bfd_sender(struct bfd_softc *, u_int);
void		 bfd_input(struct bfd_softc *, struct mbuf *);
void		 bfd_set_state(struct bfd_softc *, int);

int	 bfd_send(struct bfd_softc *, struct mbuf *);
void	 bfd_send_control(void *);

void	 bfd_start_task(void *);
void	 bfd_send_task(void *);
void	 bfd_timeout_rx(void *);
void	 bfd_timeout_tx(void *);

void	 bfd_upcall(struct socket *, caddr_t, int);
void	 bfd_senddown(struct bfd_softc *);
void	 bfd_reset(struct bfd_softc *);

#ifdef DDB
void	 bfd_debug(struct bfd_softc *);
extern void db_print_sa(struct sockaddr *);	/* XXX - sys/net/route.c */
#endif


TAILQ_HEAD(bfd_queue, bfd_softc)  bfd_queue;

/*
 * allocate a new bfd session
 */
int
bfd_rtalloc(struct rtentry *rt, struct bfd_flags *flags)
{
	struct bfd_softc	*sc;

	/* make sure we don't already have this setup */
	TAILQ_FOREACH(sc, &bfd_queue, bfd_next) {
		if (sc->sc_rt == rt)
			return (EADDRINUSE);
	}

	/* XXX - do we need to force RTM_RESOLVE? */

	/* Do our necessary memory allocations upfront */
	if ((sc = pool_get(&bfd_pool, PR_WAITOK | PR_ZERO)) == NULL)
		goto nomem;
	if ((sc->sc_peer = pool_get(&bfd_pool_peer, PR_WAITOK | PR_ZERO)) == NULL)
		goto nomem2;

	sc->sc_rt = rt;
//	rtref(sc->sc_rt);	/* we depend on this route not going away */

	bfd_reset(sc);
	sc->sc_peer->LocalDiscr = arc4random();	/* XXX - MUST be globally unique */

	if (!timeout_initialized(&sc->sc_timo_rx))
		timeout_set(&sc->sc_timo_rx, bfd_timeout_rx, sc);
	if (!timeout_initialized(&sc->sc_timo_tx))
		timeout_set(&sc->sc_timo_tx, bfd_timeout_tx, sc);

	TAILQ_INSERT_TAIL(&bfd_queue, sc, bfd_next);

	task_set(&sc->sc_bfd_task, bfd_start_task, sc);
	task_add(bfdtq, &sc->sc_bfd_task);

	return (0);

	pool_put(&bfd_pool_peer, sc);
 nomem2:
	pool_put(&bfd_pool, sc);
 nomem:
	return (ENOMEM);
}

/*
 * remove and free a bfd session
 */
int
bfd_rtfree(struct rtentry *rt)
{
	struct bfd_softc *sc;

	if ((sc = bfd_lookup(rt)) == NULL)
		return (ENOENT);

	timeout_del(&sc->sc_timo_rx);
	timeout_del(&sc->sc_timo_tx);
	task_del(bfdtq, &sc->sc_bfd_send_task);

/* XXX - punt this off to a task */
	TAILQ_REMOVE(&bfd_queue, sc, bfd_next);

	/* send suicide packets immediately */
	if (rtisvalid(sc->sc_rt))
		bfd_senddown(sc);

	soclose(sc->sc_so);
//	sc->sc_so->so_upcall = NULL;
	sc->sc_so = NULL;
	pool_put(&bfd_pool_peer, sc->sc_peer);
	pool_put(&bfd_pool, sc);

	return (0);
}

/*
 * Create and initialize the global bfd framework
 */
void
bfdinit(void)
{
	pool_init(&bfd_pool, sizeof(struct bfd_softc), 0, 0, 0,
	    "bfd_softc", NULL);
	pool_setipl(&bfd_pool, IPL_SOFTNET);
	pool_init(&bfd_pool_peer, sizeof(struct bfd_state), 0, 0, 0,
	    "bfd_softc_peer", NULL);
	pool_setipl(&bfd_pool_peer, IPL_SOFTNET);

	bfdtq = taskq_create("bfd", 1, IPL_SOFTNET, 0);
	if (bfdtq == NULL)
		panic("unable to create BFD taskq");

	TAILQ_INIT(&bfd_queue);
}

/* 
 * Destroy all bfd sessions and remove the tasks
 *
 */
void
bfddestroy(void)
{
	struct bfd_softc	*sc;

	/* send suicide packets immediately */
	while ((sc = TAILQ_FIRST(&bfd_queue))) {
		bfd_rtfree(sc->sc_rt);
	}

	taskq_destroy(bfdtq);
	pool_destroy(&bfd_pool);
	pool_destroy(&bfd_pool_peer);
}

/*
 * End of public interfaces.
 *
 * Everything below this line should not be used outside of this file.
 */

/*
 * Return the matching bfd
 */
struct bfd_softc *
bfd_lookup(struct rtentry *rt)
{
	struct bfd_softc *sc;

	TAILQ_FOREACH(sc, &bfd_queue, bfd_next) {
		if (sc->sc_rt == rt)
			return (sc);
	}
	return (NULL);
}

/*
 * Task to listen and kick off the bfd process
 */
void
bfd_start_task(void *arg)
{
	struct bfd_softc	*sc = (struct bfd_softc *)arg;

	/* start listeners */
	sc->sc_so = bfd_listener(sc, BFD_UDP_PORT_CONTROL);
	if (!sc->sc_so)
		printf("bfd_listener(%d) failed\n",
		    BFD_UDP_PORT_CONTROL);
	sc->sc_soecho = bfd_listener(sc, BFD_UDP_PORT_ECHO);
	if (!sc->sc_soecho)
		printf("bfd_listener(%d) failed\n",
		    BFD_UDP_PORT_ECHO);

	/* start sending */
	sc->sc_sosend = bfd_sender(sc, BFD_UDP_PORT_CONTROL);
	if (sc->sc_sosend) {
		task_set(&sc->sc_bfd_send_task, bfd_send_task, sc);
		task_add(bfdtq, &sc->sc_bfd_send_task);	
	}

	return;
}

void
bfd_send_task(void *arg)
{
	struct bfd_softc	*sc = (struct bfd_softc *)arg;

	/* add 70%-90% jitter to our transmits, rfc 5880 6.8.7 */
	if (!timeout_pending(&sc->sc_timo_tx))
		timeout_add_usec(&sc->sc_timo_tx,
		    sc->mintx * (arc4random_uniform(20) + 70) / 100);

	return;
}

/*
 * Setup a bfd listener socket
 */
struct socket *
bfd_listener(struct bfd_softc *sc, u_int port)
{
	struct proc		*p = curproc;
	struct rtentry		*rt = sc->sc_rt;
	struct sockaddr		*src = rt->rt_ifa->ifa_addr;
	struct sockaddr		*dst = rt->rt_gateway;
	struct sockaddr		*sa;
	struct sockaddr_in	*sin;
	struct sockaddr_in6	*sin6;
	struct socket		*so;
	struct mbuf		*m = NULL, *mopt = NULL;
	int			*ip, error;

	/* sa_family and sa_len must be equal */
	if (src->sa_family != dst->sa_family || src->sa_len != dst->sa_len)
		return (NULL);

	error = socreate(dst->sa_family, &so, SOCK_DGRAM, 0);
	if (error) {
		printf("%s: socreate error %d\n",
		    __func__, error);
		return (NULL);
	}

	MGET(mopt, M_WAIT, MT_SOOPTS);
	mopt->m_len = sizeof(int);
	ip = mtod(mopt, int *);
	*ip = MAXTTL;
	error = sosetopt(so, IPPROTO_IP, IP_MINTTL, mopt);
	if (error) {
		printf("%s: sosetopt error %d\n",
		    __func__, error);
		goto close;
	}

	MGET(m, M_WAIT, MT_SONAME);
	m->m_len = src->sa_len;
	sa = mtod(m, struct sockaddr *);
	memcpy(sa, src, src->sa_len);
	switch(sa->sa_family) {
	case AF_INET:
		sin = (struct sockaddr_in *)sa;
		sin->sin_port = htons(port);
		break;
	case AF_INET6:
		sin6 = (struct sockaddr_in6 *)sa;
		sin6->sin6_port = htons(port);
		break;
	default:
		break;
	}

	error = sobind(so, m, p);
	if (error) {
		printf("%s: sobind error %d\n",
		    __func__, error);
		goto close;
	}
	so->so_upcallarg = (caddr_t)sc;
	so->so_upcall = bfd_upcall;

	return (so);

 close:
	m_free(m);
	soclose(so);

	return (NULL);
}

/*
 * Setup the bfd sending process
 */
struct socket *
bfd_sender(struct bfd_softc *sc, u_int port)
{
	struct socket 		*so;
	struct rtentry		*rt = sc->sc_rt;
	struct proc		*p = curproc;
	struct mbuf		*m = NULL, *mopt = NULL;
	struct sockaddr		*src = rt->rt_ifa->ifa_addr;
	struct sockaddr		*dst = rt->rt_gateway;
	struct sockaddr		*sa;
	struct sockaddr_in6	*sin6;
	struct sockaddr_in	*sin;
	int		 error, *ip;

	/* sa_family and sa_len must be equal */
	if (src->sa_family != dst->sa_family || src->sa_len != dst->sa_len)
		return (NULL);

	error = socreate(dst->sa_family, &so, SOCK_DGRAM, 0);

	if (error)
		return (NULL);

	MGET(mopt, M_WAIT, MT_SOOPTS);
	mopt->m_len = sizeof(int);
	ip = mtod(mopt, int *);
	*ip = IP_PORTRANGE_HIGH;
	error = sosetopt(so, IPPROTO_IP, IP_PORTRANGE, mopt);
	if (error) {
		printf("%s: sosetopt error %d\n",
		    __func__, error);
		goto close;
	}

	MGET(mopt, M_WAIT, MT_SOOPTS);
	mopt->m_len = sizeof(int);
	ip = mtod(mopt, int *);
	*ip = MAXTTL;
	error = sosetopt(so, IPPROTO_IP, IP_TTL, mopt);
	if (error) {
		printf("%s: sosetopt error %d\n",
		    __func__, error);
		goto close;
	}

	MGET(m, M_WAIT, MT_SONAME);
	m->m_len = src->sa_len;
	sa = mtod(m, struct sockaddr *);
	memcpy(sa, src, src->sa_len);
	switch(sa->sa_family) {
	case AF_INET:
		sin = (struct sockaddr_in *)sa;
		sin->sin_port = 0;
		break;
	case AF_INET6:
		sin6 = (struct sockaddr_in6 *)sa;
		sin6->sin6_port = 0;
		break;
	default:
		break;
	}

	error = sobind(so, m, p);
	if (error) {
		printf("%s: sobind error %d\n",
		    __func__, error);
		goto close;
	}

	memcpy(sa, dst, dst->sa_len);
	switch(sa->sa_family) {
	case AF_INET:
		sin = (struct sockaddr_in *)sa;
		sin->sin_port = ntohs(port);
		break;
	case AF_INET6:
		sin6 = (struct sockaddr_in6 *)sa;
		sin6->sin6_port = ntohs(port);
		break;
	default:
		break;
	}

	error = soconnect(so, m);
	if (error && error != ECONNREFUSED) {
		printf("%s: soconnect error %d\n",
		    __func__, error);
		goto close;
	}

	m_free(m);

	return (so);

 close:
	m_free(m);
	soclose(so);

	return (NULL);
}

/*
 * Will be called per-received packet
 */
void
bfd_upcall(struct socket *so, caddr_t arg, int waitflag)
{
	struct bfd_softc *sc = (struct bfd_softc *)arg;
	struct mbuf *m;
	struct uio uio;
	int flags, error;

	uio.uio_procp = NULL;
	do {
		uio.uio_resid = 1000000000;
		flags = MSG_DONTWAIT;
		error = soreceive(so, NULL, &uio, &m, NULL, &flags, 0);
		if (error && error != EAGAIN) {
			sc->error++;
			return;
		}
		if (m != NULL)
			bfd_input(sc, m);
	} while (m != NULL);

	return;
}


void
bfd_timeout_tx(void *v)
{
	struct bfd_softc	*sc = v;
	struct rtentry		*rt = sc->sc_rt;

	if (ISSET(rt->rt_gwroute->rt_flags, RTF_UP)) {
		bfd_send_control(sc);
	} else {
		sc->error++;
		sc->sc_peer->LocalDiag = BFD_DIAG_ADMIN_DOWN;
		if (sc->sc_peer->SessionState > BFD_STATE_DOWN) {
			bfd_reset(sc);
			bfd_set_state(sc, BFD_STATE_DOWN);
		}
	}

	/* add 70%-90% jitter to our transmits, rfc 5880 6.8.7 */
	if (!timeout_pending(&sc->sc_timo_tx))
		timeout_add_usec(&sc->sc_timo_tx,
		    sc->mintx * (arc4random_uniform(20) + 70) / 100);
}

/*
 * Triggers when we do not receive a valid packet in time
 */
void
bfd_timeout_rx(void *v)
{
	struct bfd_softc *sc = v;


	if ((sc->sc_peer->SessionState > BFD_STATE_DOWN) &&
	    (++sc->error >= sc->sc_peer->DetectMult)) {
		sc->sc_peer->LocalDiag = BFD_DIAG_EXPIRED;
printf("%s: failed, sc->error %u\n", __func__, sc->error);
		bfd_reset(sc);
		bfd_set_state(sc, BFD_STATE_DOWN);

		return;
	}

	timeout_add_usec(&sc->sc_timo_rx, sc->minrx);

}

/*
 * Tell our neighbor that we are going down
 */
void
bfd_senddown(struct bfd_softc *sc)
{
	/* If we are down, return early */
	if (sc->state < BFD_STATE_INIT);
		return;

	sc->sc_peer->SessionState = BFD_STATE_ADMINDOWN;
	if (sc->sc_peer->LocalDiag == 0)
		sc->sc_peer->LocalDiag = BFD_DIAG_ADMIN_DOWN;

	bfd_send_control(sc);

	return;
}

/*
 * Clean a BFD peer to defaults
 */
void
bfd_reset(struct bfd_softc *sc)
{
if (sc->error)
printf("%s: error=%u\n", __func__, sc->error);

	/* Clean */
	sc->sc_peer->RemoteDiscr = 0;
	sc->sc_peer->DemandMode = 0;
	sc->sc_peer->RemoteDemandMode = 0;
	sc->sc_peer->AuthType = 0;
	sc->sc_peer->RcvAuthSeq = 0;
	sc->sc_peer->XmitAuthSeq = 0;
	sc->sc_peer->AuthSeqKnown = 0;
	sc->sc_peer->LocalDiag = 0;

	sc->mode = BFD_MODE_ACTIVE;
	sc->state = BFD_STATE_DOWN;

	/* Set RFC mandated values */
	sc->sc_peer->SessionState = BFD_STATE_DOWN;
	sc->sc_peer->RemoteSessionState = BFD_STATE_DOWN;
	sc->sc_peer->DesiredMinTxInterval = BFD_SECOND;
	sc->sc_peer->RequiredMinRxInterval = BFD_SECOND; /* rfc5880 6.8.18 */
	sc->sc_peer->RemoteMinRxInterval = 1;
	sc->sc_peer->DetectMult = 3; /* XXX - MUST be nonzero */

	sc->mintx = sc->sc_peer->DesiredMinTxInterval;
	sc->minrx = sc->sc_peer->RemoteMinRxInterval;
	sc->multiplier = sc->sc_peer->DetectMult;
printf("%s: localdiscr: 0x%x\n", __func__, sc->sc_peer->LocalDiscr);

	return;
}

void
bfd_input(struct bfd_softc *sc, struct mbuf *m)
{
	struct bfd_header	*peer;
	struct bfd_auth_header	*auth;
	struct mbuf		*mp, *mp0;
	u_int			 ver, diag, state, flags;
	int			 offp;

	mp = m_pulldown(m, 0, sizeof(*peer), &offp);

	if (mp == NULL)
		return;
	peer = (struct bfd_header *)(mp->m_data + offp);

	/* We only support BFD Version 1 */
	if (( ver = BFD_VER(peer->bfd_ver_diag)) != 1)
		goto discard;

	diag = BFD_DIAG(peer->bfd_ver_diag);
	state = BFD_STATE(peer->bfd_sta_flags);
	flags = BFD_FLAGS(peer->bfd_sta_flags);

	if (peer->bfd_length + offp != mp->m_len) {
		printf("%s: bad len %d != %d\n", __func__, peer->bfd_length + offp, mp->m_len);
		goto discard;
	}

	if (peer->bfd_detect_multi == 0)
		goto discard;
	if  (ntohl(peer->bfd_my_discriminator) == 0)
		goto discard;
	if (ntohl(peer->bfd_your_discriminator) == 0 &&
	    BFD_STATE(peer->bfd_sta_flags) > BFD_STATE_DOWN)
		goto discard;
	if ((ntohl(peer->bfd_your_discriminator) != 0) &&
	    (ntohl(peer->bfd_your_discriminator) != sc->sc_peer->LocalDiscr)) {
		sc->error++;
printf("%s: peer your discr 0x%x != local 0x%x\n",
    __func__, ntohl(peer->bfd_your_discriminator), sc->sc_peer->LocalDiscr);
		sc->sc_peer->LocalDiag = BFD_DIAG_EXPIRED;
		bfd_senddown(sc);
		goto discard;
	}

	if ((flags & BFD_FLAG_A) && sc->sc_peer->AuthType == 0)
		goto discard;
	if (!(flags & BFD_FLAG_A) && sc->sc_peer->AuthType != 0)
		goto discard;
	if (flags & BFD_FLAG_A) {
		mp0 = m_pulldown(mp, 0, sizeof(*auth), &offp);
		if (mp0 == NULL)
			goto discard;
		auth = (struct bfd_auth_header *)(mp0->m_data + offp);
#if 0
		if (bfd_process_auth(sc, auth) != 0) {
			m_free(mp0);
			goto discard;
		}
#endif
	}

	if ((sc->sc_peer->RemoteDiscr == 0) &&
	    (ntohl(peer->bfd_my_discriminator) != 0))
		sc->sc_peer->RemoteDiscr = ntohl(peer->bfd_my_discriminator);

	if (sc->sc_peer->RemoteDiscr != ntohl(peer->bfd_my_discriminator))
		goto discard;

	sc->sc_peer->RemoteSessionState = state;

	sc->sc_peer->RemoteMinRxInterval =
	    ntohl(peer->bfd_required_min_rx_interval);
	/* Local change to the algorithm, we don't accept below 10ms */
	if (sc->sc_peer->RequiredMinRxInterval < BFD_MINIMUM)
		goto discard;
	/*
	 * Local change to the algorithm, we can't use larger than signed
	 * 32bits for a timeout.
	 * That is Too Long(tm) anyways.
	 */
	if (sc->sc_peer->RequiredMinRxInterval > INT32_MAX)
		goto discard;
	sc->minrx = sc->sc_peer->RequiredMinRxInterval;

	sc->sc_peer->DesiredMinTxInterval =
	    htonl(peer->bfd_desired_min_tx_interval);
	if (sc->sc_peer->SessionState != BFD_STATE_UP)
		sc->sc_peer->DesiredMinTxInterval = BFD_SECOND;

	sc->sc_peer->RequiredMinRxInterval =
	    ntohl(peer->bfd_required_min_rx_interval);

	/* rfc5880 6.8.7 */
	sc->mintx = max(sc->sc_peer->RemoteMinRxInterval,
	    sc->sc_peer->DesiredMinTxInterval);

	if (sc->sc_peer->RemoteSessionState == BFD_STATE_ADMINDOWN) {
		if (sc->sc_peer->SessionState != BFD_STATE_DOWN) {
			sc->sc_peer->LocalDiag = BFD_DIAG_NEIGHBOR_SIGDOWN;
			sc->sc_peer->SessionState = BFD_STATE_DOWN;
		}
		goto discard;
	}

	/* According the to pseudo-code RFC 5880 page 34 */
	if (sc->sc_peer->SessionState == BFD_STATE_DOWN) {
printf("%s: BFD_STATE_DOWN remote 0x%x  ", __func__, ntohl(peer->bfd_my_discriminator));
printf("local 0x%x\n", ntohl(peer->bfd_your_discriminator));
bfd_debug(sc);
		if (sc->sc_peer->RemoteSessionState == BFD_STATE_DOWN)
			sc->sc_peer->SessionState = BFD_STATE_INIT;
		else if (sc->sc_peer->RemoteSessionState == BFD_STATE_INIT) {
printf("%s: set BFD_STATE_UP\n", __func__);
			sc->sc_peer->LocalDiag = 0;
			bfd_set_state(sc, BFD_STATE_UP);
		}
	} else if (sc->sc_peer->SessionState == BFD_STATE_INIT) {
printf("%s: BFD_STATE_INIT remote 0x%x  ", __func__, ntohl(peer->bfd_my_discriminator));
printf("local 0x%x\n", ntohl(peer->bfd_your_discriminator));

		if (sc->sc_peer->RemoteSessionState >= BFD_STATE_INIT) {
printf("%s: set BFD_STATE_UP\n", __func__);
			sc->sc_peer->LocalDiag = 0;
			bfd_set_state(sc, BFD_STATE_UP);
		} else {
			goto discard;
		}
	} else {
		if (sc->sc_peer->RemoteSessionState == BFD_STATE_DOWN) {
printf("%s: set BFD_STATE_DOWN\n", __func__);
			sc->sc_peer->LocalDiag = BFD_DIAG_NEIGHBOR_SIGDOWN;
			bfd_set_state(sc, BFD_STATE_DOWN);
			goto discard;
		}
	}

	if (sc->sc_peer->SessionState == BFD_STATE_UP) {
		sc->sc_peer->LocalDiag = 0;
		sc->sc_peer->DemandMode = 1;
		sc->sc_peer->RemoteDemandMode = (flags & BFD_FLAG_D);
	}

	sc->error = 0;

 discard:
	m_free(m);

	task_add(bfdtq, &sc->sc_bfd_send_task);	
	timeout_add_usec(&sc->sc_timo_rx, sc->minrx);

	return;
}

void
bfd_set_state(struct bfd_softc *sc, int state)
{
	struct ifnet	*ifp;
	struct rtentry	*rt = sc->sc_rt;
	int		 new_state;

	ifp = if_get(rt->rt_ifidx);
	if (ifp == NULL) {
		printf("%s: cannot find interface index %u\n",
		    __func__, rt->rt_ifidx);
		sc->error++;
		bfd_reset(sc);
		return;
	}
	sc->sc_peer->SessionState = state;

	if (!rtisvalid(rt))
		sc->sc_peer->SessionState = BFD_STATE_ADMINDOWN;

	switch (sc->sc_peer->SessionState) {
	case BFD_STATE_ADMINDOWN:
		new_state = RTM_BFD;
//		rt->rt_flags &= ~RTF_BFDUP;
//		rt->rt_flags |= RTF_BFDDOWN;
		break;
	case BFD_STATE_DOWN:
		new_state = RTM_BFD;
//		rt->rt_flags &= ~RTF_BFDUP;
//		rt->rt_flags |= RTF_BFDDOWN;
		break;
	case BFD_STATE_UP:
		new_state = RTM_BFD;
//		rt->rt_flags &= ~RTF_BFDDOWN;
//		rt->rt_flags |= RTF_BFDUP;
		break;
	}

printf("%s: BFD set linkstate %u (oldstate: %u)\n", ifp->if_xname, new_state, state);
	rt_sendmsg(rt, new_state, ifp->if_rdomain);

	if_put(ifp);

	return;
}

void
bfd_send_control(void *x)
{
	struct bfd_softc	*sc = x;
	struct mbuf		*m;
	struct bfd_header	bfd;
	int error;

	MGETHDR(m, M_WAIT, MT_DATA);
	MCLGET(m, M_WAIT);

	m->m_len = m->m_pkthdr.len = sizeof(bfd);

	memset(&bfd, 0xff, sizeof(bfd));	/* canary */

	bfd.bfd_ver_diag = ((BFD_VERSION << 5) | (sc->sc_peer->LocalDiag));
	bfd.bfd_sta_flags = (sc->sc_peer->SessionState << 6);
	bfd.bfd_detect_multi = sc->sc_peer->DetectMult;
	bfd.bfd_length = BFD_HDRLEN;
	bfd.bfd_my_discriminator = htonl(sc->sc_peer->LocalDiscr);
	bfd.bfd_your_discriminator = htonl(sc->sc_peer->RemoteDiscr);

	bfd.bfd_desired_min_tx_interval =
	    htonl(sc->sc_peer->DesiredMinTxInterval);
	bfd.bfd_required_min_rx_interval =
	    htonl(sc->sc_peer->RequiredMinRxInterval);
	bfd.bfd_required_min_echo_interval =
	    htonl(sc->sc_peer->RemoteMinRxInterval);

	m_copyback(m, 0, BFD_HDRLEN, &bfd, M_NOWAIT);

	error = bfd_send(sc, m);

	if (error) {
		if (!(error == EHOSTDOWN || error == ECONNREFUSED)) {
			printf("%s: %u\n", __func__, error);
		}
	}
}

int
bfd_send(struct bfd_softc *sc, struct mbuf *m)
{
	struct rtentry *rt = sc->sc_rt;

	if (!ISSET(rt->rt_gwroute->rt_flags, RTF_UP)) {
		m_free(m);
		return (EHOSTDOWN);
	}

	return (sosend(sc->sc_sosend, NULL, NULL, m, NULL, MSG_DONTWAIT));
}



#ifdef DDB

/*
 * Print debug information about this bfd instance
 */
void
bfd_debug(struct bfd_softc *sc)
{
	struct ifnet	*ifp;
	struct rtentry	*rt = sc->sc_rt;

	ifp = if_get(rt->rt_ifidx);

	if (ifp == NULL) {
	printf("%s: cannot find interface index %u\n",
	    __func__, rt->rt_ifidx);
		return;
	}

	printf("session state: %u ", sc->state);
	printf("mode: %u ", sc->mode);
	printf("error: %u ", sc->error);
	printf("minrx: %u ", sc->minrx);
	printf("mintx: %u ", sc->mintx);
	printf("multiplier: %u ", sc->multiplier);
	printf("\n");
	printf("\t");
	printf("session state: %u ", sc->sc_peer->SessionState);
	printf("local diag: %u ", sc->sc_peer->LocalDiag);
	printf("\n");
	printf("\t");
	printf("remote discriminator: 0x%x ", sc->sc_peer->RemoteDiscr);
	printf("local discriminator: 0x%x ", sc->sc_peer->LocalDiscr);
	printf("\n");
	printf("\t");
	printf("remote session state: %u ", sc->sc_peer->RemoteSessionState);
	printf("remote diag: %u ", sc->sc_peer->RemoteDiag);
	printf("remote min rx: %u ", sc->sc_peer->RemoteMinRxInterval);
	printf("\n");

	if_put(ifp);
}
#endif /* DDB */