labelmapping.c

/*	$OpenBSD$ */

/*
 * Copyright (c) 2014, 2015 Renato Westphal <renato@openbsd.org>
 * Copyright (c) 2009 Michele Marchetto <michele@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.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netmpls/mpls.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>

#include "ldpd.h"
#include "ldpe.h"
#include "log.h"

static void	 enqueue_pdu(struct nbr *, struct ibuf *, uint16_t);
static int	 gen_label_tlv(struct ibuf *, uint32_t);
static int	 tlv_decode_label(struct nbr *, struct ldp_msg *, char *,
		    uint16_t, uint32_t *);
static int	 gen_reqid_tlv(struct ibuf *, uint32_t);

static void
enqueue_pdu(struct nbr *nbr, struct ibuf *buf, uint16_t size)
{
	struct ldp_hdr		*ldp_hdr;

	ldp_hdr = ibuf_seek(buf, 0, sizeof(struct ldp_hdr));
	ldp_hdr->length = htons(size);
	evbuf_enqueue(&nbr->tcp->wbuf, buf);
}

/* Generic function that handles all Label Message types */
void
send_labelmessage(struct nbr *nbr, uint16_t type, struct mapping_head *mh)
{
	struct ibuf		*buf = NULL;
	struct mapping_entry	*me;
	uint16_t		 msg_size, size = 0;
	int			 first = 1;
	int			 err = 0;

	/* nothing to send */
	if (TAILQ_EMPTY(mh))
		return;

	while ((me = TAILQ_FIRST(mh)) != NULL) {
		/* generate pdu */
		if (first) {
			if ((buf = ibuf_open(nbr->max_pdu_len +
			    LDP_HDR_DEAD_LEN)) == NULL)
				fatal(__func__);

			/* real size will be set up later */
			err |= gen_ldp_hdr(buf, 0);

			size = LDP_HDR_PDU_LEN;
			first = 0;
		}

		/* calculate size */
		msg_size = LDP_MSG_SIZE + TLV_HDR_SIZE;
		switch (me->map.type) {
		case MAP_TYPE_WILDCARD:
			msg_size += FEC_ELM_WCARD_LEN;
			break;
		case MAP_TYPE_PREFIX:
			msg_size += FEC_ELM_PREFIX_MIN_LEN +
			    PREFIX_SIZE(me->map.fec.prefix.prefixlen);
			break;
		case MAP_TYPE_PWID:
			msg_size += FEC_PWID_ELM_MIN_LEN;
			if (me->map.flags & F_MAP_PW_ID)
				msg_size += PW_STATUS_TLV_LEN;
			if (me->map.flags & F_MAP_PW_IFMTU)
				msg_size += FEC_SUBTLV_IFMTU_SIZE;
	    		if (me->map.flags & F_MAP_PW_STATUS)
				msg_size += PW_STATUS_TLV_SIZE;
			break;
		}
		if (me->map.label != NO_LABEL)
			msg_size += LABEL_TLV_SIZE;
		if (me->map.flags & F_MAP_REQ_ID)
			msg_size += REQID_TLV_SIZE;
		if (me->map.flags & F_MAP_STATUS)
			msg_size += STATUS_SIZE;

		/* maximum pdu length exceeded, we need a new ldp pdu */
		if (size + msg_size > nbr->max_pdu_len) {
			enqueue_pdu(nbr, buf, size);
			first = 1;
			continue;
		}

		size += msg_size;

		/* append message and tlvs */
		err |= gen_msg_hdr(buf, type, msg_size);
		err |= gen_fec_tlv(buf, &me->map);
		if (me->map.label != NO_LABEL)
			err |= gen_label_tlv(buf, me->map.label);
		if (me->map.flags & F_MAP_REQ_ID)
			err |= gen_reqid_tlv(buf, me->map.requestid);
	    	if (me->map.flags & F_MAP_PW_STATUS)
			err |= gen_pw_status_tlv(buf, me->map.pw_status);
		if (me->map.flags & F_MAP_STATUS)
			err |= gen_status_tlv(buf, me->map.st.status_code,
			    me->map.st.msg_id, me->map.st.msg_type);
		if (err) {
			ibuf_free(buf);
			mapping_list_clr(mh);
			return;
		}

		log_debug("msg-out: %s: lsr-id %s, fec %s, label %s",
		    msg_name(type), inet_ntoa(nbr->id), log_map(&me->map),
		    log_label(me->map.label));

		TAILQ_REMOVE(mh, me, entry);
		free(me);
	}

	enqueue_pdu(nbr, buf, size);

	nbr_fsm(nbr, NBR_EVT_PDU_SENT);
}

/* Generic function that handles all Label Message types */
int
recv_labelmessage(struct nbr *nbr, char *buf, uint16_t len, uint16_t type)
{
	struct ldp_msg		 msg;
	struct tlv		 ft;
	uint32_t		 label = NO_LABEL, reqid = 0;
	uint32_t		 pw_status = 0;
	uint8_t			 flags = 0;
	int			 feclen, lbllen, tlen;
	struct mapping_entry	*me;
	struct mapping_head	 mh;
	struct map		 map;

	memcpy(&msg, buf, sizeof(msg));
	buf += LDP_MSG_SIZE;
	len -= LDP_MSG_SIZE;

	/* FEC TLV */
	if (len < sizeof(ft)) {
		session_shutdown(nbr, S_BAD_TLV_LEN, msg.id, msg.type);
		return (-1);
	}

	memcpy(&ft, buf, sizeof(ft));
	if (ntohs(ft.type) != TLV_TYPE_FEC) {
		send_notification_nbr(nbr, S_MISS_MSG, msg.id, msg.type);
		return (-1);
	}
	feclen = ntohs(ft.length);
	if (feclen > len - TLV_HDR_SIZE) {
		session_shutdown(nbr, S_BAD_TLV_LEN, msg.id, msg.type);
		return (-1);
	}

	buf += TLV_HDR_SIZE;	/* just advance to the end of the fec header */
	len -= TLV_HDR_SIZE;

	TAILQ_INIT(&mh);
	do {
		memset(&map, 0, sizeof(map));
		map.msg_id = msg.id;

		if ((tlen = tlv_decode_fec_elm(nbr, &msg, buf, feclen,
		    &map)) == -1)
			goto err;
		if (map.type == MAP_TYPE_PWID &&
		    !(map.flags & F_MAP_PW_ID) &&
		    type != MSG_TYPE_LABELWITHDRAW &&
		    type != MSG_TYPE_LABELRELEASE) {
			send_notification_nbr(nbr, S_MISS_MSG, msg.id,
			    msg.type);
			return (-1);
		}

		/*
		 * The Wildcard FEC Element can be used only in the
		 * Label Withdraw and Label Release messages.
		 */
		if (map.type == MAP_TYPE_WILDCARD) {
			switch (type) {
			case MSG_TYPE_LABELMAPPING:
			case MSG_TYPE_LABELREQUEST:
			case MSG_TYPE_LABELABORTREQ:
				session_shutdown(nbr, S_UNKNOWN_FEC, msg.id,
				    msg.type);
				goto err;
			default:
				break;
			}
		}

		/*
		 * LDP supports the use of multiple FEC Elements per
		 * FEC for the Label Mapping message only.
		 */
		if (type != MSG_TYPE_LABELMAPPING &&
		    tlen != feclen) {
			session_shutdown(nbr, S_BAD_TLV_VAL, msg.id, msg.type);
			goto err;
		}

		mapping_list_add(&mh, &map);

		buf += tlen;
		len -= tlen;
		feclen -= tlen;
	} while (feclen > 0);

	/* Mandatory Label TLV */
	if (type == MSG_TYPE_LABELMAPPING) {
		lbllen = tlv_decode_label(nbr, &msg, buf, len, &label);
		if (lbllen == -1)
			goto err;

		buf += lbllen;
		len -= lbllen;
	}

	/* Optional Parameters */
	while (len > 0) {
		struct tlv 	tlv;
		uint16_t	tlv_len;
		uint32_t	reqbuf, labelbuf, statusbuf;

		if (len < sizeof(tlv)) {
			session_shutdown(nbr, S_BAD_TLV_LEN, msg.id, msg.type);
			goto err;
		}

		memcpy(&tlv, buf, TLV_HDR_SIZE);
		tlv_len = ntohs(tlv.length);
		if (tlv_len + TLV_HDR_SIZE > len) {
			session_shutdown(nbr, S_BAD_TLV_LEN, msg.id, msg.type);
			goto err;
		}
		buf += TLV_HDR_SIZE;
		len -= TLV_HDR_SIZE;

		switch (ntohs(tlv.type)) {
		case TLV_TYPE_LABELREQUEST:
			switch (type) {
			case MSG_TYPE_LABELMAPPING:
			case MSG_TYPE_LABELREQUEST:
				if (tlv_len != REQID_TLV_LEN) {
					session_shutdown(nbr, S_BAD_TLV_LEN,
					    msg.id, msg.type);
					goto err;
				}

				flags |= F_MAP_REQ_ID;
				memcpy(&reqbuf, buf, sizeof(reqbuf));
				reqid = ntohl(reqbuf);
				break;
			default:
				/* ignore */
				break;
			}
			break;
		case TLV_TYPE_HOPCOUNT:
		case TLV_TYPE_PATHVECTOR:
			/* ignore */
			break;
		case TLV_TYPE_GENERICLABEL:
			switch (type) {
			case MSG_TYPE_LABELWITHDRAW:
			case MSG_TYPE_LABELRELEASE:
				if (tlv_len != LABEL_TLV_LEN) {
					session_shutdown(nbr, S_BAD_TLV_LEN,
					    msg.id, msg.type);
					goto err;
				}

				memcpy(&labelbuf, buf, sizeof(labelbuf));
				label = ntohl(labelbuf);
				break;
			default:
				/* ignore */
				break;
			}
			break;
		case TLV_TYPE_ATMLABEL:
		case TLV_TYPE_FRLABEL:
			switch (type) {
			case MSG_TYPE_LABELWITHDRAW:
			case MSG_TYPE_LABELRELEASE:
				/* unsupported */
				session_shutdown(nbr, S_BAD_TLV_VAL, msg.id,
				    msg.type);
				goto err;
				break;
			default:
				/* ignore */
				break;
			}
			break;
		case TLV_TYPE_STATUS:
			if (tlv_len != STATUS_TLV_LEN) {
				session_shutdown(nbr, S_BAD_TLV_LEN, msg.id,
				    msg.type);
				goto err;
			}
			/* ignore */
			break;
		case TLV_TYPE_PW_STATUS:
			switch (type) {
			case MSG_TYPE_LABELMAPPING:
				if (tlv_len != PW_STATUS_TLV_LEN) {
					session_shutdown(nbr, S_BAD_TLV_LEN,
					    msg.id, msg.type);
					goto err;
				}

				flags |= F_MAP_PW_STATUS;
				memcpy(&statusbuf, buf, sizeof(statusbuf));
				pw_status = ntohl(statusbuf);
				break;
			default:
				/* ignore */
				break;
			}
			break;
		default:
			if (!(ntohs(tlv.type) & UNKNOWN_FLAG))
				send_notification_nbr(nbr, S_UNKNOWN_TLV,
				    msg.id, msg.type);
			/* ignore unknown tlv */
			break;
		}
		buf += tlv_len;
		len -= tlv_len;
	}

	/* notify lde about the received message. */
	while ((me = TAILQ_FIRST(&mh)) != NULL) {
		int imsg_type = IMSG_NONE;

		me->map.flags |= flags;
		switch (me->map.type) {
		case MAP_TYPE_PREFIX:
			switch (me->map.fec.prefix.af) {
			case AF_INET:
				if (label == MPLS_LABEL_IPV6NULL) {
					session_shutdown(nbr, S_BAD_TLV_VAL,
					    msg.id, msg.type);
					goto err;
				}
				if (!nbr->v4_enabled)
					goto next;
				break;
			case AF_INET6:
				if (label == MPLS_LABEL_IPV4NULL) {
					session_shutdown(nbr, S_BAD_TLV_VAL,
					    msg.id, msg.type);
					goto err;
				}
				if (!nbr->v6_enabled)
					goto next;
				break;
			default:
				fatalx("recv_labelmessage: unknown af");
			}
			break;
		case MAP_TYPE_PWID:
			if (label <= MPLS_LABEL_RESERVED_MAX) {
				session_shutdown(nbr, S_BAD_TLV_VAL, msg.id,
				    msg.type);
				goto err;
			}
			if (me->map.flags & F_MAP_PW_STATUS)
				me->map.pw_status = pw_status;
			break;
		default:
			break;
		}
		me->map.label = label;
		if (me->map.flags & F_MAP_REQ_ID)
			me->map.requestid = reqid;

		log_debug("msg-in: label mapping: lsr-id %s, fec %s, label %s",
		    inet_ntoa(nbr->id), log_map(&me->map),
		    log_label(me->map.label));

		switch (type) {
		case MSG_TYPE_LABELMAPPING:
			imsg_type = IMSG_LABEL_MAPPING;
			break;
		case MSG_TYPE_LABELREQUEST:
			imsg_type = IMSG_LABEL_REQUEST;
			break;
		case MSG_TYPE_LABELWITHDRAW:
			imsg_type = IMSG_LABEL_WITHDRAW;
			break;
		case MSG_TYPE_LABELRELEASE:
			imsg_type = IMSG_LABEL_RELEASE;
			break;
		case MSG_TYPE_LABELABORTREQ:
			imsg_type = IMSG_LABEL_ABORT;
			break;
		default:
			break;
		}

		ldpe_imsg_compose_lde(imsg_type, nbr->peerid, 0, &me->map,
		    sizeof(struct map));

next:
		TAILQ_REMOVE(&mh, me, entry);
		free(me);
	}

	return (0);

err:
	mapping_list_clr(&mh);

	return (-1);
}

/* Other TLV related functions */
static int
gen_label_tlv(struct ibuf *buf, uint32_t label)
{
	struct label_tlv	lt;

	lt.type = htons(TLV_TYPE_GENERICLABEL);
	lt.length = htons(LABEL_TLV_LEN);
	lt.label = htonl(label);

	return (ibuf_add(buf, &lt, sizeof(lt)));
}

static int
tlv_decode_label(struct nbr *nbr, struct ldp_msg *msg, char *buf,
    uint16_t len, uint32_t *label)
{
	struct label_tlv lt;

	if (len < sizeof(lt)) {
		session_shutdown(nbr, S_BAD_TLV_LEN, msg->id, msg->type);
		return (-1);
	}
	memcpy(&lt, buf, sizeof(lt));

	if (!(ntohs(lt.type) & TLV_TYPE_GENERICLABEL)) {
		send_notification_nbr(nbr, S_MISS_MSG, msg->id, msg->type);
		return (-1);
	}

	switch (htons(lt.type)) {
	case TLV_TYPE_GENERICLABEL:
		if (ntohs(lt.length) != sizeof(lt) - TLV_HDR_SIZE) {
			session_shutdown(nbr, S_BAD_TLV_LEN, msg->id,
			    msg->type);
			return (-1);
		}

		*label = ntohl(lt.label);
		if (*label > MPLS_LABEL_MAX ||
		    (*label <= MPLS_LABEL_RESERVED_MAX &&
		     *label != MPLS_LABEL_IPV4NULL &&
		     *label != MPLS_LABEL_IPV6NULL &&
		     *label != MPLS_LABEL_IMPLNULL)) {
			session_shutdown(nbr, S_BAD_TLV_VAL, msg->id,
			    msg->type);
			return (-1);
		}
		break;
	case TLV_TYPE_ATMLABEL:
	case TLV_TYPE_FRLABEL:
	default:
		/* unsupported */
		session_shutdown(nbr, S_BAD_TLV_VAL, msg->id, msg->type);
		return (-1);
	}

	return (sizeof(lt));
}

static int
gen_reqid_tlv(struct ibuf *buf, uint32_t reqid)
{
	struct reqid_tlv	rt;

	rt.type = htons(TLV_TYPE_LABELREQUEST);
	rt.length = htons(REQID_TLV_LEN);
	rt.reqid = htonl(reqid);

	return (ibuf_add(buf, &rt, sizeof(rt)));
}

int
gen_pw_status_tlv(struct ibuf *buf, uint32_t status)
{
	struct pw_status_tlv	st;

	st.type = htons(TLV_TYPE_PW_STATUS);
	st.length = htons(PW_STATUS_TLV_LEN);
	st.value = htonl(status);

	return (ibuf_add(buf, &st, sizeof(st)));
}

int
gen_fec_tlv(struct ibuf *buf, struct map *map)
{
	struct tlv	ft;
	uint16_t	family, len, pw_type, ifmtu;
	uint8_t		pw_len = 0;
	uint32_t	group_id, pwid;
	int		err = 0;

	ft.type = htons(TLV_TYPE_FEC);

	switch (map->type) {
	case MAP_TYPE_WILDCARD:
		ft.length = htons(sizeof(uint8_t));
		err |= ibuf_add(buf, &ft, sizeof(ft));
		err |= ibuf_add(buf, &map->type, sizeof(map->type));
		break;
	case MAP_TYPE_PREFIX:
		len = PREFIX_SIZE(map->fec.prefix.prefixlen);
		ft.length = htons(sizeof(map->type) + sizeof(family) +
		    sizeof(map->fec.prefix.prefixlen) + len);
		err |= ibuf_add(buf, &ft, sizeof(ft));
		err |= ibuf_add(buf, &map->type, sizeof(map->type));
		switch (map->fec.prefix.af) {
		case AF_INET:
			family = htons(AF_IPV4);
			break;
		case AF_INET6:
			family = htons(AF_IPV6);
			break;
		default:
			fatalx("gen_fec_tlv: unknown af");
			break;
		}
		err |= ibuf_add(buf, &family, sizeof(family));
		err |= ibuf_add(buf, &map->fec.prefix.prefixlen,
		    sizeof(map->fec.prefix.prefixlen));
		if (len)
			err |= ibuf_add(buf, &map->fec.prefix.prefix, len);
		break;
	case MAP_TYPE_PWID:
		if (map->flags & F_MAP_PW_ID)
			pw_len += PW_STATUS_TLV_LEN;
		if (map->flags & F_MAP_PW_IFMTU)
			pw_len += FEC_SUBTLV_IFMTU_SIZE;

		len = FEC_PWID_ELM_MIN_LEN + pw_len;

		ft.length = htons(len);
		err |= ibuf_add(buf, &ft, sizeof(ft));

		err |= ibuf_add(buf, &map->type, sizeof(uint8_t));
		pw_type = map->fec.pwid.type;
		if (map->flags & F_MAP_PW_CWORD)
			pw_type |= CONTROL_WORD_FLAG;
		pw_type = htons(pw_type);
		err |= ibuf_add(buf, &pw_type, sizeof(uint16_t));
		err |= ibuf_add(buf, &pw_len, sizeof(uint8_t));
		group_id = htonl(map->fec.pwid.group_id);
		err |= ibuf_add(buf, &group_id, sizeof(uint32_t));
		if (map->flags & F_MAP_PW_ID) {
			pwid = htonl(map->fec.pwid.pwid);
			err |= ibuf_add(buf, &pwid, sizeof(uint32_t));
		}
		if (map->flags & F_MAP_PW_IFMTU) {
			struct subtlv 	stlv;

			stlv.type = SUBTLV_IFMTU;
			stlv.length = FEC_SUBTLV_IFMTU_SIZE;
			err |= ibuf_add(buf, &stlv, sizeof(uint16_t));

			ifmtu = htons(map->fec.pwid.ifmtu);
			err |= ibuf_add(buf, &ifmtu, sizeof(uint16_t));
		}
		break;
	default:
		break;
	}

	return (err);
}

int
tlv_decode_fec_elm(struct nbr *nbr, struct ldp_msg *msg, char *buf,
    uint16_t len, struct map *map)
{
	uint16_t	off = 0;
	uint8_t		pw_len;

	map->type = *buf;
	off += sizeof(uint8_t);

	switch (map->type) {
	case MAP_TYPE_WILDCARD:
		if (len == FEC_ELM_WCARD_LEN)
			return (off);
		else {
			session_shutdown(nbr, S_BAD_TLV_VAL, msg->id,
			    msg->type);
			return (-1);
		}
		break;
	case MAP_TYPE_PREFIX:
		if (len < FEC_ELM_PREFIX_MIN_LEN) {
			session_shutdown(nbr, S_BAD_TLV_LEN, msg->id,
			    msg->type);
			return (-1);
		}

		/* Address Family */
		memcpy(&map->fec.prefix.af, buf + off,
		    sizeof(map->fec.prefix.af));
		off += sizeof(map->fec.prefix.af);
		map->fec.prefix.af = ntohs(map->fec.prefix.af);
		switch (map->fec.prefix.af) {
		case AF_IPV4:
			map->fec.prefix.af = AF_INET;
			break;
		case AF_IPV6:
			map->fec.prefix.af = AF_INET6;
			break;
		default:
			send_notification_nbr(nbr, S_UNSUP_ADDR, msg->id,
			    msg->type);
			return (-1);
		}

		/* Prefix Length */
		map->fec.prefix.prefixlen = buf[off];
		off += sizeof(uint8_t);
		if (len < off + PREFIX_SIZE(map->fec.prefix.prefixlen)) {
			session_shutdown(nbr, S_BAD_TLV_LEN, msg->id,
			    msg->type);
			return (-1);
		}

		/* Prefix */
		memset(&map->fec.prefix.prefix, 0,
		    sizeof(map->fec.prefix.prefix));
		memcpy(&map->fec.prefix.prefix, buf + off,
		    PREFIX_SIZE(map->fec.prefix.prefixlen));

		/* Just in case... */
		ldp_applymask(map->fec.prefix.af, &map->fec.prefix.prefix,
		    &map->fec.prefix.prefix, map->fec.prefix.prefixlen);

		return (off + PREFIX_SIZE(map->fec.prefix.prefixlen));
	case MAP_TYPE_PWID:
		if (len < FEC_PWID_ELM_MIN_LEN) {
			session_shutdown(nbr, S_BAD_TLV_LEN, msg->id,
			    msg->type);
			return (-1);
		}

		/* PW type */
		memcpy(&map->fec.pwid.type, buf + off, sizeof(uint16_t));
		map->fec.pwid.type = ntohs(map->fec.pwid.type);
		if (map->fec.pwid.type & CONTROL_WORD_FLAG) {
			map->flags |= F_MAP_PW_CWORD;
			map->fec.pwid.type &= ~CONTROL_WORD_FLAG;
		}
		off += sizeof(uint16_t);

		/* PW info Length */
		pw_len = buf[off];
		off += sizeof(uint8_t);

		if (len != FEC_PWID_ELM_MIN_LEN + pw_len) {
			session_shutdown(nbr, S_BAD_TLV_LEN, msg->id,
			    msg->type);
			return (-1);
		}

		/* Group ID */
		memcpy(&map->fec.pwid.group_id, buf + off, sizeof(uint32_t));
		map->fec.pwid.group_id = ntohl(map->fec.pwid.group_id);
		off += sizeof(uint32_t);

		/* PW ID */
		if (pw_len == 0)
			return (off);

		if (pw_len < sizeof(uint32_t)) {
			session_shutdown(nbr, S_BAD_TLV_LEN, msg->id,
			    msg->type);
			return (-1);
		}

		memcpy(&map->fec.pwid.pwid, buf + off, sizeof(uint32_t));
		map->fec.pwid.pwid = ntohl(map->fec.pwid.pwid);
		map->flags |= F_MAP_PW_ID;
		off += sizeof(uint32_t);
		pw_len -= sizeof(uint32_t);

		/* Optional Interface Parameter Sub-TLVs */
		while (pw_len > 0) {
			struct subtlv 	stlv;

			if (pw_len < sizeof(stlv)) {
				session_shutdown(nbr, S_BAD_TLV_LEN, msg->id,
				    msg->type);
				return (-1);
			}

			memcpy(&stlv, buf + off, sizeof(stlv));
			if (stlv.length > pw_len) {
				session_shutdown(nbr, S_BAD_TLV_LEN, msg->id,
				    msg->type);
				return (-1);
			}

			switch (stlv.type) {
			case SUBTLV_IFMTU:
				if (stlv.length != FEC_SUBTLV_IFMTU_SIZE) {
					session_shutdown(nbr, S_BAD_TLV_LEN,
					    msg->id, msg->type);
					return (-1);
				}
				memcpy(&map->fec.pwid.ifmtu, buf + off +
				    SUBTLV_HDR_SIZE, sizeof(uint16_t));
				map->fec.pwid.ifmtu = ntohs(map->fec.pwid.ifmtu);
				map->flags |= F_MAP_PW_IFMTU;
				break;
			default:
				/* ignore */
				break;
			}
			off += stlv.length;
			pw_len -= stlv.length;
		}

		return (off);
	default:
		send_notification_nbr(nbr, S_UNKNOWN_FEC, msg->id, msg->type);
		break;
	}

	return (-1);
}