1 files changed, 1010 insertions, 0 deletions

diff --git a/bfdd/ptm_adapter.c b/bfdd/ptm_adapter.c
new file mode 100644
index 0000000..f6259b9
--- /dev/null
+++ b/bfdd/ptm_adapter.c
@@ -0,0 +1,1010 @@
+/*
+ * BFD PTM adapter code
+ * Copyright (C) 2018 Network Device Education Foundation, Inc. ("NetDEF")
+ *
+ * FRR 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, or (at your option) any
+ * later version.
+ *
+ * FRR 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 FRR; see the file COPYING.  If not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <zebra.h>
+
+#include "lib/libfrr.h"
+#include "lib/queue.h"
+#include "lib/stream.h"
+#include "lib/zclient.h"
+#include "lib/printfrr.h"
+
+#include "lib/bfd.h"
+
+#include "bfd.h"
+
+/*
+ * Data structures
+ */
+struct ptm_client_notification {
+	struct bfd_session *pcn_bs;
+	struct ptm_client *pcn_pc;
+
+	TAILQ_ENTRY(ptm_client_notification) pcn_entry;
+};
+TAILQ_HEAD(pcnqueue, ptm_client_notification);
+
+struct ptm_client {
+	uint32_t pc_pid;
+	struct pcnqueue pc_pcnqueue;
+
+	TAILQ_ENTRY(ptm_client) pc_entry;
+};
+TAILQ_HEAD(pcqueue, ptm_client);
+
+static struct pcqueue pcqueue;
+static struct zclient *zclient;
+
+
+/*
+ * Prototypes
+ */
+static int _ptm_msg_address(struct stream *msg, int family, const void *addr);
+
+static void _ptm_msg_read_address(struct stream *msg, struct sockaddr_any *sa);
+static int _ptm_msg_read(struct stream *msg, int command, vrf_id_t vrf_id,
+			 struct bfd_peer_cfg *bpc, struct ptm_client **pc);
+
+static struct ptm_client *pc_lookup(uint32_t pid);
+static struct ptm_client *pc_new(uint32_t pid);
+static void pc_free(struct ptm_client *pc);
+static void pc_free_all(void);
+static struct ptm_client_notification *pcn_new(struct ptm_client *pc,
+					       struct bfd_session *bs);
+static struct ptm_client_notification *pcn_lookup(struct ptm_client *pc,
+						  struct bfd_session *bs);
+static void pcn_free(struct ptm_client_notification *pcn);
+
+
+static void bfdd_dest_register(struct stream *msg, vrf_id_t vrf_id);
+static void bfdd_dest_deregister(struct stream *msg, vrf_id_t vrf_id);
+static void bfdd_client_register(struct stream *msg);
+static void bfdd_client_deregister(struct stream *msg);
+
+/*
+ * Functions
+ */
+static void debug_printbpc(const struct bfd_peer_cfg *bpc, const char *fmt, ...)
+{
+	char timers[3][128] = {};
+	char minttl_str[32] = {};
+	char addr[3][128] = {};
+	char profile[128] = {};
+	char cbit_str[32];
+	char msgbuf[512];
+	va_list vl;
+
+	/* Avoid debug calculations if it's disabled. */
+	if (bglobal.debug_zebra == false)
+		return;
+
+	snprintf(addr[0], sizeof(addr[0]), "peer:%s", satostr(&bpc->bpc_peer));
+	if (bpc->bpc_local.sa_sin.sin_family)
+		snprintf(addr[1], sizeof(addr[1]), " local:%s",
+			 satostr(&bpc->bpc_local));
+
+	if (bpc->bpc_has_localif)
+		snprintf(addr[2], sizeof(addr[2]), " ifname:%s",
+			 bpc->bpc_localif);
+
+	if (bpc->bpc_has_vrfname)
+		snprintf(addr[2], sizeof(addr[2]), " vrf:%s", bpc->bpc_vrfname);
+
+	if (bpc->bpc_has_recvinterval)
+		snprintfrr(timers[0], sizeof(timers[0]), " rx:%" PRIu64,
+			   bpc->bpc_recvinterval);
+
+	if (bpc->bpc_has_txinterval)
+		snprintfrr(timers[1], sizeof(timers[1]), " tx:%" PRIu64,
+			   bpc->bpc_recvinterval);
+
+	if (bpc->bpc_has_detectmultiplier)
+		snprintf(timers[2], sizeof(timers[2]), " detect-multiplier:%d",
+			 bpc->bpc_detectmultiplier);
+
+	snprintf(cbit_str, sizeof(cbit_str), " cbit:0x%02x", bpc->bpc_cbit);
+
+	if (bpc->bpc_has_minimum_ttl)
+		snprintf(minttl_str, sizeof(minttl_str), " minimum-ttl:%d",
+			 bpc->bpc_minimum_ttl);
+
+	if (bpc->bpc_has_profile)
+		snprintf(profile, sizeof(profile), " profile:%s",
+			 bpc->bpc_profile);
+
+	va_start(vl, fmt);
+	vsnprintf(msgbuf, sizeof(msgbuf), fmt, vl);
+	va_end(vl);
+
+	zlog_debug("%s [mhop:%s %s%s%s%s%s%s%s%s%s]", msgbuf,
+		   bpc->bpc_mhop ? "yes" : "no", addr[0], addr[1], addr[2],
+		   timers[0], timers[1], timers[2], cbit_str, minttl_str,
+		   profile);
+}
+
+static void _ptm_bfd_session_del(struct bfd_session *bs, uint8_t diag)
+{
+	if (bglobal.debug_peer_event)
+		zlog_debug("session-delete: %s", bs_to_string(bs));
+
+	/* Change state and notify peer. */
+	bs->ses_state = PTM_BFD_DOWN;
+	bs->local_diag = diag;
+	ptm_bfd_snd(bs, 0);
+
+	/* Session reached refcount == 0, lets delete it. */
+	if (bs->refcount == 0) {
+		/*
+		 * Sanity check: if there is a refcount bug, we can't delete
+		 * the session a user configured manually. Lets leave a
+		 * message here so we can catch the bug if it exists.
+		 */
+		if (CHECK_FLAG(bs->flags, BFD_SESS_FLAG_CONFIG)) {
+			zlog_err(
+				"ptm-del-session: [%s] session refcount is zero but it was configured by CLI",
+				bs_to_string(bs));
+		} else {
+			control_notify_config(BCM_NOTIFY_CONFIG_DELETE, bs);
+			bfd_session_free(bs);
+		}
+	}
+}
+
+static int _ptm_msg_address(struct stream *msg, int family, const void *addr)
+{
+	stream_putc(msg, family);
+
+	switch (family) {
+	case AF_INET:
+		stream_put(msg, addr, sizeof(struct in_addr));
+		stream_putc(msg, 32);
+		break;
+
+	case AF_INET6:
+		stream_put(msg, addr, sizeof(struct in6_addr));
+		stream_putc(msg, 128);
+		break;
+
+	default:
+		assert(0);
+		break;
+	}
+
+	return 0;
+}
+
+int ptm_bfd_notify(struct bfd_session *bs, uint8_t notify_state)
+{
+	struct stream *msg;
+
+	bs->stats.znotification++;
+
+	/*
+	 * Message format:
+	 * - header: command, vrf
+	 * - l: interface index
+	 * - c: family
+	 *   - AF_INET:
+	 *     - 4 bytes: ipv4
+	 *   - AF_INET6:
+	 *     - 16 bytes: ipv6
+	 *   - c: prefix length
+	 * - l: bfd status
+	 * - c: family
+	 *   - AF_INET:
+	 *     - 4 bytes: ipv4
+	 *   - AF_INET6:
+	 *     - 16 bytes: ipv6
+	 *   - c: prefix length
+	 * - c: cbit
+	 *
+	 * Commands: ZEBRA_BFD_DEST_REPLAY
+	 *
+	 * q(64), l(32), w(16), c(8)
+	 */
+	msg = zclient->obuf;
+	stream_reset(msg);
+
+	/* TODO: VRF handling */
+	if (bs->vrf)
+		zclient_create_header(msg, ZEBRA_BFD_DEST_REPLAY, bs->vrf->vrf_id);
+	else
+		zclient_create_header(msg, ZEBRA_BFD_DEST_REPLAY, VRF_DEFAULT);
+
+	/* This header will be handled by `zebra_ptm.c`. */
+	stream_putl(msg, ZEBRA_INTERFACE_BFD_DEST_UPDATE);
+
+	/* NOTE: Interface is a shortcut to avoid comparing source address. */
+	if (!CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH) && bs->ifp != NULL)
+		stream_putl(msg, bs->ifp->ifindex);
+	else
+		stream_putl(msg, IFINDEX_INTERNAL);
+
+	/* BFD destination prefix information. */
+	_ptm_msg_address(msg, bs->key.family, &bs->key.peer);
+
+	/* BFD status */
+	switch (notify_state) {
+	case PTM_BFD_UP:
+		stream_putl(msg, BFD_STATUS_UP);
+		break;
+
+	case PTM_BFD_ADM_DOWN:
+		stream_putl(msg, BFD_STATUS_ADMIN_DOWN);
+		break;
+
+	case PTM_BFD_DOWN:
+	case PTM_BFD_INIT:
+		stream_putl(msg, BFD_STATUS_DOWN);
+		break;
+
+	default:
+		stream_putl(msg, BFD_STATUS_UNKNOWN);
+		break;
+	}
+
+	/* BFD source prefix information. */
+	_ptm_msg_address(msg, bs->key.family, &bs->key.local);
+
+	stream_putc(msg, bs->remote_cbit);
+
+	/* Write packet size. */
+	stream_putw_at(msg, 0, stream_get_endp(msg));
+
+	return zclient_send_message(zclient);
+}
+
+static void _ptm_msg_read_address(struct stream *msg, struct sockaddr_any *sa)
+{
+	uint16_t family;
+
+	STREAM_GETW(msg, family);
+
+	switch (family) {
+	case AF_INET:
+		sa->sa_sin.sin_family = family;
+		STREAM_GET(&sa->sa_sin.sin_addr, msg,
+			   sizeof(sa->sa_sin.sin_addr));
+#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
+		sa->sa_sin.sin_len = sizeof(sa->sa_sin);
+#endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
+		return;
+
+	case AF_INET6:
+		sa->sa_sin6.sin6_family = family;
+		STREAM_GET(&sa->sa_sin6.sin6_addr, msg,
+			   sizeof(sa->sa_sin6.sin6_addr));
+#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
+		sa->sa_sin6.sin6_len = sizeof(sa->sa_sin6);
+#endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
+		return;
+
+	default:
+		zlog_warn("ptm-read-address: invalid family: %d", family);
+		break;
+	}
+
+stream_failure:
+	memset(sa, 0, sizeof(*sa));
+}
+
+static int _ptm_msg_read(struct stream *msg, int command, vrf_id_t vrf_id,
+			 struct bfd_peer_cfg *bpc, struct ptm_client **pc)
+{
+	uint32_t pid;
+	size_t ifnamelen;
+
+	/*
+	 * Register/Deregister/Update Message format:
+	 *
+	 * Old format (being used by PTM BFD).
+	 * - header: Command, VRF
+	 * - l: pid
+	 * - w: family
+	 *   - AF_INET:
+	 *     - l: destination ipv4
+	 *   - AF_INET6:
+	 *     - 16 bytes: destination IPv6
+	 * - command != ZEBRA_BFD_DEST_DEREGISTER
+	 *   - l: min_rx
+	 *   - l: min_tx
+	 *   - c: detect multiplier
+	 * - c: is_multihop?
+	 *   - multihop:
+	 *     - w: family
+	 *       - AF_INET:
+	 *         - l: source IPv4 address
+	 *       - AF_INET6:
+	 *         - 16 bytes: source IPv6 address
+	 *     - c: ttl
+	 *   - no multihop
+	 *     - AF_INET6:
+	 *       - w: family
+	 *       - 16 bytes: source IPv6 address
+	 *     - c: ifname length
+	 *     - X bytes: interface name
+	 *
+	 * New format:
+	 * - header: Command, VRF
+	 * - l: pid
+	 * - w: family
+	 *   - AF_INET:
+	 *     - l: destination IPv4 address
+	 *   - AF_INET6:
+	 *     - 16 bytes: destination IPv6 address
+	 * - l: min_rx
+	 * - l: min_tx
+	 * - c: detect multiplier
+	 * - c: is_multihop?
+	 * - w: family
+	 *   - AF_INET:
+	 *     - l: source IPv4 address
+	 *   - AF_INET6:
+	 *     - 16 bytes: source IPv6 address
+	 * - c: ttl
+	 * - c: ifname length
+	 * - X bytes: interface name
+	 * - c: bfd_cbit
+	 * - c: profile name length.
+	 * - X bytes: profile name.
+	 *
+	 * q(64), l(32), w(16), c(8)
+	 */
+
+	/* Initialize parameters return values. */
+	memset(bpc, 0, sizeof(*bpc));
+	*pc = NULL;
+
+	/* Find or allocate process context data. */
+	STREAM_GETL(msg, pid);
+
+	*pc = pc_new(pid);
+
+	/* Register/update peer information. */
+	_ptm_msg_read_address(msg, &bpc->bpc_peer);
+
+	/* Determine IP type from peer destination. */
+	bpc->bpc_ipv4 = (bpc->bpc_peer.sa_sin.sin_family == AF_INET);
+
+	/* Get peer configuration. */
+	STREAM_GETL(msg, bpc->bpc_recvinterval);
+	bpc->bpc_has_recvinterval =
+		(bpc->bpc_recvinterval != BPC_DEF_RECEIVEINTERVAL);
+
+	STREAM_GETL(msg, bpc->bpc_txinterval);
+	bpc->bpc_has_txinterval =
+		(bpc->bpc_txinterval != BPC_DEF_TRANSMITINTERVAL);
+
+	STREAM_GETC(msg, bpc->bpc_detectmultiplier);
+	bpc->bpc_has_detectmultiplier =
+		(bpc->bpc_detectmultiplier != BPC_DEF_DETECTMULTIPLIER);
+
+	/* Read (single|multi)hop and its options. */
+	STREAM_GETC(msg, bpc->bpc_mhop);
+
+	/* Read multihop source address and TTL. */
+	_ptm_msg_read_address(msg, &bpc->bpc_local);
+
+	/* Read the minimum TTL (0 means unset or invalid). */
+	STREAM_GETC(msg, bpc->bpc_minimum_ttl);
+	if (bpc->bpc_minimum_ttl == 0) {
+		bpc->bpc_minimum_ttl = BFD_DEF_MHOP_TTL;
+		bpc->bpc_has_minimum_ttl = false;
+	} else {
+		bpc->bpc_minimum_ttl = (BFD_TTL_VAL + 1) - bpc->bpc_minimum_ttl;
+		bpc->bpc_has_minimum_ttl = true;
+	}
+
+	/*
+	 * Read interface name and make sure it fits our data
+	 * structure, otherwise fail.
+	 */
+	STREAM_GETC(msg, ifnamelen);
+	if (ifnamelen >= sizeof(bpc->bpc_localif)) {
+		zlog_err("ptm-read: interface name is too big");
+		return -1;
+	}
+
+	bpc->bpc_has_localif = ifnamelen > 0;
+	if (bpc->bpc_has_localif) {
+		STREAM_GET(bpc->bpc_localif, msg, ifnamelen);
+		bpc->bpc_localif[ifnamelen] = 0;
+	}
+
+	if (vrf_id != VRF_DEFAULT) {
+		struct vrf *vrf;
+
+		vrf = vrf_lookup_by_id(vrf_id);
+		if (vrf) {
+			bpc->bpc_has_vrfname = true;
+			strlcpy(bpc->bpc_vrfname, vrf->name, sizeof(bpc->bpc_vrfname));
+		} else {
+			zlog_err("ptm-read: vrf id %u could not be identified",
+				 vrf_id);
+			return -1;
+		}
+	} else {
+		bpc->bpc_has_vrfname = true;
+		strlcpy(bpc->bpc_vrfname, VRF_DEFAULT_NAME, sizeof(bpc->bpc_vrfname));
+	}
+
+	/* Read control plane independant configuration. */
+	STREAM_GETC(msg, bpc->bpc_cbit);
+
+	/* Handle profile names. */
+	STREAM_GETC(msg, ifnamelen);
+	bpc->bpc_has_profile = ifnamelen > 0;
+	if (bpc->bpc_has_profile) {
+		STREAM_GET(bpc->bpc_profile, msg, ifnamelen);
+		bpc->bpc_profile[ifnamelen] = 0;
+	}
+
+	/* Sanity check: peer and local address must match IP types. */
+	if (bpc->bpc_local.sa_sin.sin_family != AF_UNSPEC
+	    && (bpc->bpc_local.sa_sin.sin_family
+		!= bpc->bpc_peer.sa_sin.sin_family)) {
+		zlog_warn("ptm-read: peer family doesn't match local type");
+		return -1;
+	}
+
+	return 0;
+
+stream_failure:
+	return -1;
+}
+
+static void bfdd_dest_register(struct stream *msg, vrf_id_t vrf_id)
+{
+	struct ptm_client *pc;
+	struct bfd_session *bs;
+	struct bfd_peer_cfg bpc;
+
+	/* Read the client context and peer data. */
+	if (_ptm_msg_read(msg, ZEBRA_BFD_DEST_REGISTER, vrf_id, &bpc, &pc) == -1)
+		return;
+
+	debug_printbpc(&bpc, "ptm-add-dest: register peer");
+
+	/* Find or start new BFD session. */
+	bs = bs_peer_find(&bpc);
+	if (bs == NULL) {
+		bs = ptm_bfd_sess_new(&bpc);
+		if (bs == NULL) {
+			if (bglobal.debug_zebra)
+				zlog_debug(
+					"ptm-add-dest: failed to create BFD session");
+			return;
+		}
+	} else {
+		/*
+		 * BFD session was already created, we are just updating the
+		 * current peer.
+		 *
+		 * `ptm-bfd` (or `HAVE_BFDD == 0`) is the only implementation
+		 * that allow users to set peer specific timers via protocol.
+		 * BFD daemon (this code) on the other hand only supports
+		 * changing peer configuration manually (through `peer` node)
+		 * or via profiles.
+		 */
+		if (bpc.bpc_has_profile)
+			bfd_profile_apply(bpc.bpc_profile, bs);
+	}
+
+	/* Create client peer notification register. */
+	pcn_new(pc, bs);
+
+	ptm_bfd_notify(bs, bs->ses_state);
+}
+
+static void bfdd_dest_deregister(struct stream *msg, vrf_id_t vrf_id)
+{
+	struct ptm_client *pc;
+	struct ptm_client_notification *pcn;
+	struct bfd_session *bs;
+	struct bfd_peer_cfg bpc;
+
+	/* Read the client context and peer data. */
+	if (_ptm_msg_read(msg, ZEBRA_BFD_DEST_DEREGISTER, vrf_id, &bpc, &pc) == -1)
+		return;
+
+	debug_printbpc(&bpc, "ptm-del-dest: deregister peer");
+
+	/* Find or start new BFD session. */
+	bs = bs_peer_find(&bpc);
+	if (bs == NULL) {
+		if (bglobal.debug_zebra)
+			zlog_debug("ptm-del-dest: failed to find BFD session");
+		return;
+	}
+
+	/* Unregister client peer notification. */
+	pcn = pcn_lookup(pc, bs);
+	if (pcn != NULL) {
+		pcn_free(pcn);
+		return;
+	}
+
+	if (bglobal.debug_zebra)
+		zlog_debug("ptm-del-dest: failed to find BFD session");
+
+	/*
+	 * XXX: We either got a double deregistration or the daemon who
+	 * created this is no longer around. Lets try to delete it anyway
+	 * and the worst case is the refcount will detain us.
+	 */
+	_ptm_bfd_session_del(bs, BD_NEIGHBOR_DOWN);
+}
+
+/*
+ * header: command, VRF
+ * l: pid
+ */
+static void bfdd_client_register(struct stream *msg)
+{
+	uint32_t pid;
+
+	/* Find or allocate process context data. */
+	STREAM_GETL(msg, pid);
+
+	pc_new(pid);
+
+	return;
+
+stream_failure:
+	zlog_err("ptm-add-client: failed to register client");
+}
+
+/*
+ * header: command, VRF
+ * l: pid
+ */
+static void bfdd_client_deregister(struct stream *msg)
+{
+	struct ptm_client *pc;
+	uint32_t pid;
+
+	/* Find or allocate process context data. */
+	STREAM_GETL(msg, pid);
+
+	pc = pc_lookup(pid);
+	if (pc == NULL) {
+		if (bglobal.debug_zebra)
+			zlog_debug("ptm-del-client: failed to find client: %u",
+				   pid);
+		return;
+	}
+
+	if (bglobal.debug_zebra)
+		zlog_debug("ptm-del-client: client pid %u", pid);
+
+	pc_free(pc);
+
+	return;
+
+stream_failure:
+	zlog_err("ptm-del-client: failed to deregister client");
+}
+
+static int bfdd_replay(ZAPI_CALLBACK_ARGS)
+{
+	struct stream *msg = zclient->ibuf;
+	uint32_t rcmd;
+
+	STREAM_GETL(msg, rcmd);
+
+	switch (rcmd) {
+	case ZEBRA_BFD_DEST_REGISTER:
+	case ZEBRA_BFD_DEST_UPDATE:
+		bfdd_dest_register(msg, vrf_id);
+		break;
+	case ZEBRA_BFD_DEST_DEREGISTER:
+		bfdd_dest_deregister(msg, vrf_id);
+		break;
+	case ZEBRA_BFD_CLIENT_REGISTER:
+		bfdd_client_register(msg);
+		break;
+	case ZEBRA_BFD_CLIENT_DEREGISTER:
+		bfdd_client_deregister(msg);
+		break;
+
+	default:
+		if (bglobal.debug_zebra)
+			zlog_debug("ptm-replay: invalid message type %u", rcmd);
+		return -1;
+	}
+
+	return 0;
+
+stream_failure:
+	zlog_err("ptm-replay: failed to find command");
+	return -1;
+}
+
+static void bfdd_zebra_connected(struct zclient *zc)
+{
+	struct stream *msg = zc->obuf;
+
+	/* Clean-up and free ptm clients data memory. */
+	pc_free_all();
+
+	/*
+	 * The replay is an empty message just to trigger client daemons
+	 * configuration replay.
+	 */
+	stream_reset(msg);
+	zclient_create_header(msg, ZEBRA_BFD_DEST_REPLAY, VRF_DEFAULT);
+	stream_putl(msg, ZEBRA_BFD_DEST_REPLAY);
+	stream_putw_at(msg, 0, stream_get_endp(msg));
+
+	/* Ask for interfaces information. */
+	zclient_create_header(msg, ZEBRA_INTERFACE_ADD, VRF_DEFAULT);
+
+	/* Send requests. */
+	zclient_send_message(zclient);
+}
+
+static void bfdd_sessions_enable_interface(struct interface *ifp)
+{
+	struct bfd_session_observer *bso;
+	struct bfd_session *bs;
+	struct vrf *vrf;
+
+	vrf = ifp->vrf;
+
+	TAILQ_FOREACH(bso, &bglobal.bg_obslist, bso_entry) {
+		bs = bso->bso_bs;
+		/* check vrf name */
+		if (bs->key.vrfname[0] &&
+		    strcmp(vrf->name, bs->key.vrfname))
+			continue;
+
+		/* If Interface matches vrfname, then bypass iface check */
+		if (vrf_is_backend_netns() || strcmp(ifp->name, vrf->name)) {
+			/* Interface name mismatch. */
+			if (bs->key.ifname[0] &&
+			    strcmp(ifp->name, bs->key.ifname))
+				continue;
+		}
+
+		/* Skip enabled sessions. */
+		if (bs->sock != -1)
+			continue;
+
+		/* Try to enable it. */
+		bfd_session_enable(bs);
+	}
+}
+
+static void bfdd_sessions_disable_interface(struct interface *ifp)
+{
+	struct bfd_session_observer *bso;
+	struct bfd_session *bs;
+
+	TAILQ_FOREACH(bso, &bglobal.bg_obslist, bso_entry) {
+		bs = bso->bso_bs;
+
+		if (bs->ifp != ifp)
+			continue;
+
+		/* Skip disabled sessions. */
+		if (bs->sock == -1) {
+			bs->ifp = NULL;
+			continue;
+		}
+
+		bfd_session_disable(bs);
+		bs->ifp = NULL;
+	}
+}
+
+void bfdd_sessions_enable_vrf(struct vrf *vrf)
+{
+	struct bfd_session_observer *bso;
+	struct bfd_session *bs;
+
+	/* it may affect configs without interfaces */
+	TAILQ_FOREACH(bso, &bglobal.bg_obslist, bso_entry) {
+		bs = bso->bso_bs;
+		if (bs->vrf)
+			continue;
+		if (bs->key.vrfname[0] &&
+		    strcmp(vrf->name, bs->key.vrfname))
+			continue;
+		/* need to update the vrf information on
+		 * bs so that callbacks are handled
+		 */
+		bs->vrf = vrf;
+		/* Skip enabled sessions. */
+		if (bs->sock != -1)
+			continue;
+		/* Try to enable it. */
+		bfd_session_enable(bs);
+	}
+}
+
+void bfdd_sessions_disable_vrf(struct vrf *vrf)
+{
+	struct bfd_session_observer *bso;
+	struct bfd_session *bs;
+
+	TAILQ_FOREACH(bso, &bglobal.bg_obslist, bso_entry) {
+		bs = bso->bso_bs;
+		if (bs->key.vrfname[0] &&
+		    strcmp(vrf->name, bs->key.vrfname))
+			continue;
+		/* Skip disabled sessions. */
+		if (bs->sock == -1)
+			continue;
+
+		bfd_session_disable(bs);
+		bs->vrf = NULL;
+	}
+}
+
+static int bfd_ifp_destroy(struct interface *ifp)
+{
+	if (bglobal.debug_zebra)
+		zlog_debug("zclient: delete interface %s (VRF %s(%u))",
+			   ifp->name, ifp->vrf->name, ifp->vrf->vrf_id);
+
+	bfdd_sessions_disable_interface(ifp);
+
+	return 0;
+}
+
+static int bfdd_interface_vrf_update(ZAPI_CALLBACK_ARGS)
+{
+	struct interface *ifp;
+	vrf_id_t nvrfid;
+
+	ifp = zebra_interface_vrf_update_read(zclient->ibuf, vrf_id, &nvrfid);
+	if (ifp == NULL)
+		return 0;
+
+	if_update_to_new_vrf(ifp, nvrfid);
+
+	return 0;
+}
+
+static void bfdd_sessions_enable_address(struct connected *ifc)
+{
+	struct bfd_session_observer *bso;
+	struct bfd_session *bs;
+	struct prefix prefix;
+
+	TAILQ_FOREACH(bso, &bglobal.bg_obslist, bso_entry) {
+		/* Skip enabled sessions. */
+		bs = bso->bso_bs;
+		if (bs->sock != -1)
+			continue;
+
+		/* Check address. */
+		prefix = bso->bso_addr;
+		prefix.prefixlen = ifc->address->prefixlen;
+		if (prefix_cmp(&prefix, ifc->address))
+			continue;
+
+		/* Try to enable it. */
+		bfd_session_enable(bs);
+	}
+}
+
+static int bfdd_interface_address_update(ZAPI_CALLBACK_ARGS)
+{
+	struct connected *ifc;
+
+	ifc = zebra_interface_address_read(cmd, zclient->ibuf, vrf_id);
+	if (ifc == NULL)
+		return 0;
+
+	if (bglobal.debug_zebra)
+		zlog_debug("zclient: %s local address %pFX (VRF %u)",
+			   cmd == ZEBRA_INTERFACE_ADDRESS_ADD ? "add"
+							      : "delete",
+			   ifc->address, vrf_id);
+
+	if (cmd == ZEBRA_INTERFACE_ADDRESS_ADD)
+		bfdd_sessions_enable_address(ifc);
+	else
+		connected_free(&ifc);
+
+	return 0;
+}
+
+static int bfd_ifp_create(struct interface *ifp)
+{
+	if (bglobal.debug_zebra)
+		zlog_debug("zclient: add interface %s (VRF %s(%u))", ifp->name,
+			   ifp->vrf->name, ifp->vrf->vrf_id);
+	bfdd_sessions_enable_interface(ifp);
+
+	return 0;
+}
+
+static zclient_handler *const bfd_handlers[] = {
+	/*
+	 * We'll receive all messages through replay, however it will
+	 * contain a special field with the real command inside so we
+	 * avoid having to create too many handlers.
+	 */
+	[ZEBRA_BFD_DEST_REPLAY] = bfdd_replay,
+
+	/* Learn about interface VRF. */
+	[ZEBRA_INTERFACE_VRF_UPDATE] = bfdd_interface_vrf_update,
+
+	/* Learn about new addresses being registered. */
+	[ZEBRA_INTERFACE_ADDRESS_ADD] = bfdd_interface_address_update,
+	[ZEBRA_INTERFACE_ADDRESS_DELETE] = bfdd_interface_address_update,
+};
+
+void bfdd_zclient_init(struct zebra_privs_t *bfdd_priv)
+{
+	if_zapi_callbacks(bfd_ifp_create, NULL, NULL, bfd_ifp_destroy);
+	zclient = zclient_new(master, &zclient_options_default, bfd_handlers,
+			      array_size(bfd_handlers));
+	assert(zclient != NULL);
+	zclient_init(zclient, ZEBRA_ROUTE_BFD, 0, bfdd_priv);
+
+	/* Send replay request on zebra connect. */
+	zclient->zebra_connected = bfdd_zebra_connected;
+}
+
+void bfdd_zclient_register(vrf_id_t vrf_id)
+{
+	if (!zclient || zclient->sock < 0)
+		return;
+	zclient_send_reg_requests(zclient, vrf_id);
+}
+
+void bfdd_zclient_unregister(vrf_id_t vrf_id)
+{
+	if (!zclient || zclient->sock < 0)
+		return;
+	zclient_send_dereg_requests(zclient, vrf_id);
+}
+
+void bfdd_zclient_stop(void)
+{
+	zclient_stop(zclient);
+
+	/* Clean-up and free ptm clients data memory. */
+	pc_free_all();
+}
+
+
+/*
+ * Client handling.
+ */
+static struct ptm_client *pc_lookup(uint32_t pid)
+{
+	struct ptm_client *pc;
+
+	TAILQ_FOREACH (pc, &pcqueue, pc_entry) {
+		if (pc->pc_pid != pid)
+			continue;
+
+		break;
+	}
+
+	return pc;
+}
+
+static struct ptm_client *pc_new(uint32_t pid)
+{
+	struct ptm_client *pc;
+
+	/* Look up first, if not found create the client. */
+	pc = pc_lookup(pid);
+	if (pc != NULL)
+		return pc;
+
+	/* Allocate the client data and save it. */
+	pc = XCALLOC(MTYPE_BFDD_CONTROL, sizeof(*pc));
+
+	pc->pc_pid = pid;
+	TAILQ_INSERT_HEAD(&pcqueue, pc, pc_entry);
+	return pc;
+}
+
+static void pc_free(struct ptm_client *pc)
+{
+	struct ptm_client_notification *pcn;
+
+	TAILQ_REMOVE(&pcqueue, pc, pc_entry);
+
+	while (!TAILQ_EMPTY(&pc->pc_pcnqueue)) {
+		pcn = TAILQ_FIRST(&pc->pc_pcnqueue);
+		pcn_free(pcn);
+	}
+
+	XFREE(MTYPE_BFDD_CONTROL, pc);
+}
+
+static void pc_free_all(void)
+{
+	struct ptm_client *pc;
+
+	while (!TAILQ_EMPTY(&pcqueue)) {
+		pc = TAILQ_FIRST(&pcqueue);
+		pc_free(pc);
+	}
+}
+
+static struct ptm_client_notification *pcn_new(struct ptm_client *pc,
+					       struct bfd_session *bs)
+{
+	struct ptm_client_notification *pcn;
+
+	/* Try to find an existing pcn fist. */
+	pcn = pcn_lookup(pc, bs);
+	if (pcn != NULL)
+		return pcn;
+
+	/* Save the client notification data. */
+	pcn = XCALLOC(MTYPE_BFDD_NOTIFICATION, sizeof(*pcn));
+
+	TAILQ_INSERT_HEAD(&pc->pc_pcnqueue, pcn, pcn_entry);
+	pcn->pcn_pc = pc;
+	pcn->pcn_bs = bs;
+	bs->refcount++;
+
+	return pcn;
+}
+
+static struct ptm_client_notification *pcn_lookup(struct ptm_client *pc,
+						  struct bfd_session *bs)
+{
+	struct ptm_client_notification *pcn;
+
+	TAILQ_FOREACH (pcn, &pc->pc_pcnqueue, pcn_entry) {
+		if (pcn->pcn_bs != bs)
+			continue;
+
+		break;
+	}
+
+	return pcn;
+}
+
+static void pcn_free(struct ptm_client_notification *pcn)
+{
+	struct ptm_client *pc;
+	struct bfd_session *bs;
+
+	/* Handle session de-registration. */
+	bs = pcn->pcn_bs;
+	pcn->pcn_bs = NULL;
+	bs->refcount--;
+
+	/* Log modification to users. */
+	if (bglobal.debug_zebra)
+		zlog_debug("ptm-del-session: [%s] refcount=%" PRIu64,
+			   bs_to_string(bs), bs->refcount);
+
+	/* Set session down. */
+	_ptm_bfd_session_del(bs, BD_NEIGHBOR_DOWN);
+
+	/* Handle ptm_client deregistration. */
+	pc = pcn->pcn_pc;
+	pcn->pcn_pc = NULL;
+	TAILQ_REMOVE(&pc->pc_pcnqueue, pcn, pcn_entry);
+
+	XFREE(MTYPE_BFDD_NOTIFICATION, pcn);
+}