1 files changed, 861 insertions, 0 deletions

diff --git a/bfdd/bfdd_nb_config.c b/bfdd/bfdd_nb_config.c
new file mode 100644
index 0000000..cc74d58
--- /dev/null
+++ b/bfdd/bfdd_nb_config.c
@@ -0,0 +1,861 @@
+/*
+ * BFD daemon northbound implementation.
+ *
+ * Copyright (C) 2019 Network Device Education Foundation, Inc. ("NetDEF")
+ *                    Rafael Zalamena
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301 USA.
+ */
+
+#include <zebra.h>
+
+#include "lib/log.h"
+#include "lib/northbound.h"
+
+#include "bfd.h"
+#include "bfdd_nb.h"
+
+/*
+ * Helpers.
+ */
+static void bfd_session_get_key(bool mhop, const struct lyd_node *dnode,
+				struct bfd_key *bk)
+{
+	const char *ifname = NULL, *vrfname = NULL;
+	struct sockaddr_any psa, lsa;
+
+	/* Required destination parameter. */
+	strtosa(yang_dnode_get_string(dnode, "./dest-addr"), &psa);
+
+	/* Get optional source address. */
+	memset(&lsa, 0, sizeof(lsa));
+	if (yang_dnode_exists(dnode, "./source-addr"))
+		strtosa(yang_dnode_get_string(dnode, "./source-addr"), &lsa);
+
+	vrfname = yang_dnode_get_string(dnode, "./vrf");
+
+	if (!mhop) {
+		ifname = yang_dnode_get_string(dnode, "./interface");
+		if (strcmp(ifname, "*") == 0)
+			ifname = NULL;
+	}
+
+	/* Generate the corresponding key. */
+	gen_bfd_key(bk, &psa, &lsa, mhop, ifname, vrfname);
+}
+
+struct session_iter {
+	int count;
+	bool wildcard;
+};
+
+static int session_iter_cb(const struct lyd_node *dnode, void *arg)
+{
+	struct session_iter *iter = arg;
+	const char *ifname;
+
+	ifname = yang_dnode_get_string(dnode, "./interface");
+
+	if (strmatch(ifname, "*"))
+		iter->wildcard = true;
+
+	iter->count++;
+
+	return YANG_ITER_CONTINUE;
+}
+
+static int bfd_session_create(struct nb_cb_create_args *args, bool mhop)
+{
+	const struct lyd_node *sess_dnode;
+	struct session_iter iter;
+	struct bfd_session *bs;
+	const char *dest;
+	const char *ifname;
+	const char *vrfname;
+	struct bfd_key bk;
+	struct prefix p;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+		yang_dnode_get_prefix(&p, args->dnode, "./dest-addr");
+
+		if (mhop) {
+			/*
+			 * Do not allow IPv6 link-local address for multihop.
+			 */
+			if (p.family == AF_INET6
+			    && IN6_IS_ADDR_LINKLOCAL(&p.u.prefix6)) {
+				snprintf(
+					args->errmsg, args->errmsg_len,
+					"Cannot use link-local address for multihop sessions");
+				return NB_ERR_VALIDATION;
+			}
+			return NB_OK;
+		}
+
+		/*
+		 * When `dest-addr` is IPv6 and link-local we must
+		 * require interface name, otherwise we can't figure
+		 * which interface to use to send the packets.
+		 */
+		ifname = yang_dnode_get_string(args->dnode, "./interface");
+
+		if (p.family == AF_INET6 && IN6_IS_ADDR_LINKLOCAL(&p.u.prefix6)
+		    && strcmp(ifname, "*") == 0) {
+			snprintf(
+				args->errmsg, args->errmsg_len,
+				"When using link-local you must specify an interface");
+			return NB_ERR_VALIDATION;
+		}
+
+		iter.count = 0;
+		iter.wildcard = false;
+
+		sess_dnode = yang_dnode_get_parent(args->dnode, "sessions");
+
+		dest = yang_dnode_get_string(args->dnode, "./dest-addr");
+		vrfname = yang_dnode_get_string(args->dnode, "./vrf");
+
+		yang_dnode_iterate(session_iter_cb, &iter, sess_dnode,
+				   "./single-hop[dest-addr='%s'][vrf='%s']",
+				   dest, vrfname);
+
+		if (iter.wildcard && iter.count > 1) {
+			snprintf(
+				args->errmsg, args->errmsg_len,
+				"It is not allowed to configure the same peer with and without ifname");
+			return NB_ERR_VALIDATION;
+		}
+		break;
+
+	case NB_EV_PREPARE:
+		bfd_session_get_key(mhop, args->dnode, &bk);
+		bs = bfd_key_lookup(bk);
+
+		/* This session was already configured by another daemon. */
+		if (bs != NULL) {
+			/* Now it is configured also by CLI. */
+			SET_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG);
+			bs->refcount++;
+
+			args->resource->ptr = bs;
+			break;
+		}
+
+		bs = bfd_session_new();
+
+		/* Fill the session key. */
+		bfd_session_get_key(mhop, args->dnode, &bs->key);
+
+		/* Set configuration flags. */
+		bs->refcount = 1;
+		SET_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG);
+		if (mhop)
+			SET_FLAG(bs->flags, BFD_SESS_FLAG_MH);
+		if (bs->key.family == AF_INET6)
+			SET_FLAG(bs->flags, BFD_SESS_FLAG_IPV6);
+
+		args->resource->ptr = bs;
+		break;
+
+	case NB_EV_APPLY:
+		bs = args->resource->ptr;
+
+		/* Only attempt to registrate if freshly allocated. */
+		if (bs->discrs.my_discr == 0 && bs_registrate(bs) == NULL)
+			return NB_ERR_RESOURCE;
+
+		nb_running_set_entry(args->dnode, bs);
+		break;
+
+	case NB_EV_ABORT:
+		bs = args->resource->ptr;
+		if (bs->refcount <= 1)
+			bfd_session_free(bs);
+		break;
+	}
+
+	return NB_OK;
+}
+
+static int bfd_session_destroy(enum nb_event event,
+			       const struct lyd_node *dnode, bool mhop)
+{
+	struct bfd_session *bs;
+	struct bfd_key bk;
+
+	switch (event) {
+	case NB_EV_VALIDATE:
+		bfd_session_get_key(mhop, dnode, &bk);
+		if (bfd_key_lookup(bk) == NULL)
+			return NB_ERR_INCONSISTENCY;
+		break;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		break;
+
+	case NB_EV_APPLY:
+		bs = nb_running_unset_entry(dnode);
+		/* CLI is not using this session anymore. */
+		if (CHECK_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG) == 0)
+			break;
+
+		UNSET_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG);
+		bs->refcount--;
+		/* There are still daemons using it. */
+		if (bs->refcount > 0)
+			break;
+
+		bfd_session_free(bs);
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		break;
+	}
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd
+ */
+int bfdd_bfd_create(struct nb_cb_create_args *args)
+{
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	/*
+	 * Set any non-NULL value to be able to call
+	 * nb_running_unset_entry in bfdd_bfd_destroy.
+	 */
+	nb_running_set_entry(args->dnode, (void *)0x1);
+
+	return NB_OK;
+}
+
+int bfdd_bfd_destroy(struct nb_cb_destroy_args *args)
+{
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+		/* NOTHING */
+		return NB_OK;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		return NB_OK;
+
+	case NB_EV_APPLY:
+		/*
+		 * We need to call this to unset pointers from
+		 * the child nodes - sessions and profiles.
+		 */
+		nb_running_unset_entry(args->dnode);
+
+		bfd_sessions_remove_manual();
+		bfd_profiles_remove();
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		return NB_OK;
+	}
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/profile
+ */
+int bfdd_bfd_profile_create(struct nb_cb_create_args *args)
+{
+	struct bfd_profile *bp;
+	const char *name;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	name = yang_dnode_get_string(args->dnode, "./name");
+	bp = bfd_profile_new(name);
+	nb_running_set_entry(args->dnode, bp);
+
+	return NB_OK;
+}
+
+int bfdd_bfd_profile_destroy(struct nb_cb_destroy_args *args)
+{
+	struct bfd_profile *bp;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	bp = nb_running_unset_entry(args->dnode);
+	bfd_profile_free(bp);
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/profile/detection-multiplier
+ */
+int bfdd_bfd_profile_detection_multiplier_modify(struct nb_cb_modify_args *args)
+{
+	struct bfd_profile *bp;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	bp = nb_running_get_entry(args->dnode, NULL, true);
+	bp->detection_multiplier = yang_dnode_get_uint8(args->dnode, NULL);
+	bfd_profile_update(bp);
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/profile/desired-transmission-interval
+ */
+int bfdd_bfd_profile_desired_transmission_interval_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct bfd_profile *bp;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+		break;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		break;
+
+	case NB_EV_APPLY:
+		bp = nb_running_get_entry(args->dnode, NULL, true);
+		bp->min_tx = yang_dnode_get_uint32(args->dnode, NULL);
+		bfd_profile_update(bp);
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		break;
+	}
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/profile/required-receive-interval
+ */
+int bfdd_bfd_profile_required_receive_interval_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct bfd_profile *bp;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+		break;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		break;
+
+	case NB_EV_APPLY:
+		bp = nb_running_get_entry(args->dnode, NULL, true);
+		bp->min_rx = yang_dnode_get_uint32(args->dnode, NULL);
+		bfd_profile_update(bp);
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		break;
+	}
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/profile/administrative-down
+ */
+int bfdd_bfd_profile_administrative_down_modify(struct nb_cb_modify_args *args)
+{
+	struct bfd_profile *bp;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	bp = nb_running_get_entry(args->dnode, NULL, true);
+	bp->admin_shutdown = yang_dnode_get_bool(args->dnode, NULL);
+	bfd_profile_update(bp);
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/profile/passive-mode
+ */
+int bfdd_bfd_profile_passive_mode_modify(struct nb_cb_modify_args *args)
+{
+	struct bfd_profile *bp;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	bp = nb_running_get_entry(args->dnode, NULL, true);
+	bp->passive = yang_dnode_get_bool(args->dnode, NULL);
+	bfd_profile_update(bp);
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/profile/minimum-ttl
+ */
+int bfdd_bfd_profile_minimum_ttl_modify(struct nb_cb_modify_args *args)
+{
+	struct bfd_profile *bp;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	bp = nb_running_get_entry(args->dnode, NULL, true);
+	bp->minimum_ttl = yang_dnode_get_uint8(args->dnode, NULL);
+	bfd_profile_update(bp);
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/profile/echo-mode
+ */
+int bfdd_bfd_profile_echo_mode_modify(struct nb_cb_modify_args *args)
+{
+	struct bfd_profile *bp;
+	bool echo;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	echo = yang_dnode_get_bool(args->dnode, NULL);
+	bp = nb_running_get_entry(args->dnode, NULL, true);
+	if (bp->echo_mode == echo)
+		return NB_OK;
+
+	bp->echo_mode = echo;
+	bfd_profile_update(bp);
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/profile/desired-echo-transmission-interval
+ */
+int bfdd_bfd_profile_desired_echo_transmission_interval_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct bfd_profile *bp;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+		break;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		break;
+
+	case NB_EV_APPLY:
+		bp = nb_running_get_entry(args->dnode, NULL, true);
+		bp->min_echo_tx = yang_dnode_get_uint32(args->dnode, NULL);
+		bfd_profile_update(bp);
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		break;
+	}
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/profile/required-echo-receive-interval
+ */
+int bfdd_bfd_profile_required_echo_receive_interval_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct bfd_profile *bp;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+		break;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		break;
+
+	case NB_EV_APPLY:
+		bp = nb_running_get_entry(args->dnode, NULL, true);
+		bp->min_echo_rx = yang_dnode_get_uint32(args->dnode, NULL);
+		bfd_profile_update(bp);
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		break;
+	}
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/sessions/single-hop
+ */
+int bfdd_bfd_sessions_single_hop_create(struct nb_cb_create_args *args)
+{
+	return bfd_session_create(args, false);
+}
+
+int bfdd_bfd_sessions_single_hop_destroy(struct nb_cb_destroy_args *args)
+{
+	return bfd_session_destroy(args->event, args->dnode, false);
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/sessions/single-hop/source-addr
+ */
+int bfdd_bfd_sessions_single_hop_source_addr_modify(
+	struct nb_cb_modify_args *args)
+{
+	return NB_OK;
+}
+
+int bfdd_bfd_sessions_single_hop_source_addr_destroy(
+	struct nb_cb_destroy_args *args)
+{
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/sessions/single-hop/profile
+ */
+int bfdd_bfd_sessions_single_hop_profile_modify(struct nb_cb_modify_args *args)
+{
+	struct bfd_session *bs;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	bs = nb_running_get_entry(args->dnode, NULL, true);
+	bfd_profile_apply(yang_dnode_get_string(args->dnode, NULL), bs);
+
+	return NB_OK;
+}
+
+int bfdd_bfd_sessions_single_hop_profile_destroy(
+	struct nb_cb_destroy_args *args)
+{
+	struct bfd_session *bs;
+
+	if (args->event != NB_EV_APPLY)
+		return NB_OK;
+
+	bs = nb_running_get_entry(args->dnode, NULL, true);
+	bfd_profile_remove(bs);
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/sessions/single-hop/detection-multiplier
+ */
+int bfdd_bfd_sessions_single_hop_detection_multiplier_modify(
+	struct nb_cb_modify_args *args)
+{
+	uint8_t detection_multiplier = yang_dnode_get_uint8(args->dnode, NULL);
+	struct bfd_session *bs;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+		break;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		break;
+
+	case NB_EV_APPLY:
+		bs = nb_running_get_entry(args->dnode, NULL, true);
+		bs->peer_profile.detection_multiplier = detection_multiplier;
+		bfd_session_apply(bs);
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		break;
+	}
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/sessions/single-hop/desired-transmission-interval
+ */
+int bfdd_bfd_sessions_single_hop_desired_transmission_interval_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct bfd_session *bs;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+		break;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		break;
+
+	case NB_EV_APPLY:
+		bs = nb_running_get_entry(args->dnode, NULL, true);
+		bs->peer_profile.min_tx =
+			yang_dnode_get_uint32(args->dnode, NULL);
+		bfd_session_apply(bs);
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		break;
+	}
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/sessions/single-hop/required-receive-interval
+ */
+int bfdd_bfd_sessions_single_hop_required_receive_interval_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct bfd_session *bs;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+		break;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		break;
+
+	case NB_EV_APPLY:
+		bs = nb_running_get_entry(args->dnode, NULL, true);
+		bs->peer_profile.min_rx =
+			yang_dnode_get_uint32(args->dnode, NULL);
+		bfd_session_apply(bs);
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		break;
+	}
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/sessions/single-hop/administrative-down
+ */
+int bfdd_bfd_sessions_single_hop_administrative_down_modify(
+	struct nb_cb_modify_args *args)
+{
+	bool shutdown = yang_dnode_get_bool(args->dnode, NULL);
+	struct bfd_session *bs;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+	case NB_EV_PREPARE:
+		return NB_OK;
+
+	case NB_EV_APPLY:
+		break;
+
+	case NB_EV_ABORT:
+		return NB_OK;
+	}
+
+	bs = nb_running_get_entry(args->dnode, NULL, true);
+	bs->peer_profile.admin_shutdown = shutdown;
+	bfd_session_apply(bs);
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/sessions/single-hop/passive-mode
+ */
+int bfdd_bfd_sessions_single_hop_passive_mode_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct bfd_session *bs;
+	bool passive;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+	case NB_EV_PREPARE:
+		return NB_OK;
+
+	case NB_EV_APPLY:
+		break;
+
+	case NB_EV_ABORT:
+		return NB_OK;
+	}
+
+	passive = yang_dnode_get_bool(args->dnode, NULL);
+
+	bs = nb_running_get_entry(args->dnode, NULL, true);
+	bs->peer_profile.passive = passive;
+	bfd_session_apply(bs);
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/sessions/single-hop/echo-mode
+ */
+int bfdd_bfd_sessions_single_hop_echo_mode_modify(
+	struct nb_cb_modify_args *args)
+{
+	bool echo = yang_dnode_get_bool(args->dnode, NULL);
+	struct bfd_session *bs;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+	case NB_EV_PREPARE:
+		return NB_OK;
+
+	case NB_EV_APPLY:
+		break;
+
+	case NB_EV_ABORT:
+		return NB_OK;
+	}
+
+	bs = nb_running_get_entry(args->dnode, NULL, true);
+	bs->peer_profile.echo_mode = echo;
+	bfd_session_apply(bs);
+
+	return NB_OK;
+}
+
+/*
+ * XPath:
+ * /frr-bfdd:bfdd/bfd/sessions/single-hop/desired-echo-transmission-interval
+ */
+int bfdd_bfd_sessions_single_hop_desired_echo_transmission_interval_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct bfd_session *bs;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+		break;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		break;
+
+	case NB_EV_APPLY:
+		bs = nb_running_get_entry(args->dnode, NULL, true);
+		bs->peer_profile.min_echo_tx =
+			yang_dnode_get_uint32(args->dnode, NULL);
+		bfd_session_apply(bs);
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		break;
+	}
+
+	return NB_OK;
+}
+
+/*
+ * XPath:
+ * /frr-bfdd:bfdd/bfd/sessions/single-hop/required-echo-receive-interval
+ */
+int bfdd_bfd_sessions_single_hop_required_echo_receive_interval_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct bfd_session *bs;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+		break;
+
+	case NB_EV_PREPARE:
+		/* NOTHING */
+		break;
+
+	case NB_EV_APPLY:
+		bs = nb_running_get_entry(args->dnode, NULL, true);
+		bs->peer_profile.min_echo_rx =
+			yang_dnode_get_uint32(args->dnode, NULL);
+		bfd_session_apply(bs);
+		break;
+
+	case NB_EV_ABORT:
+		/* NOTHING */
+		break;
+	}
+
+	return NB_OK;
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/sessions/multi-hop
+ */
+int bfdd_bfd_sessions_multi_hop_create(struct nb_cb_create_args *args)
+{
+	return bfd_session_create(args, true);
+}
+
+int bfdd_bfd_sessions_multi_hop_destroy(struct nb_cb_destroy_args *args)
+{
+	return bfd_session_destroy(args->event, args->dnode, true);
+}
+
+/*
+ * XPath: /frr-bfdd:bfdd/bfd/sessions/multi-hop/minimum-ttl
+ */
+int bfdd_bfd_sessions_multi_hop_minimum_ttl_modify(
+	struct nb_cb_modify_args *args)
+{
+	struct bfd_session *bs;
+
+	switch (args->event) {
+	case NB_EV_VALIDATE:
+	case NB_EV_PREPARE:
+		return NB_OK;
+
+	case NB_EV_APPLY:
+		break;
+
+	case NB_EV_ABORT:
+		return NB_OK;
+	}
+
+	bs = nb_running_get_entry(args->dnode, NULL, true);
+	bs->peer_profile.minimum_ttl = yang_dnode_get_uint8(args->dnode, NULL);
+	bfd_session_apply(bs);
+
+	return NB_OK;
+}