Adding upstream version 9.1.upstream/9.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1759 insertions, 0 deletions

diff --git a/bfdd/bfd_packet.c b/bfdd/bfd_packet.c
new file mode 100644
index 0000000..5d8bf47
--- /dev/null
+++ b/bfdd/bfd_packet.c
@@ -0,0 +1,1759 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*********************************************************************
+ * Copyright 2017 Cumulus Networks, Inc.  All rights reserved.
+ *
+ * bfd_packet.c: implements the BFD protocol packet handling.
+ *
+ * Authors
+ * -------
+ * Shrijeet Mukherjee [shm@cumulusnetworks.com]
+ * Kanna Rajagopal [kanna@cumulusnetworks.com]
+ * Radhika Mahankali [Radhika@cumulusnetworks.com]
+ */
+
+#include <zebra.h>
+
+#ifdef BFD_LINUX
+#include <linux/if_packet.h>
+#endif /* BFD_LINUX */
+
+#include <netinet/if_ether.h>
+#include <netinet/udp.h>
+
+#include "lib/sockopt.h"
+#include "lib/checksum.h"
+#include "lib/network.h"
+
+#include "bfd.h"
+
+/*
+ * Prototypes
+ */
+static int ptm_bfd_process_echo_pkt(struct bfd_vrf_global *bvrf, int s);
+int _ptm_bfd_send(struct bfd_session *bs, uint16_t *port, const void *data,
+		  size_t datalen);
+
+static void bfd_sd_reschedule(struct bfd_vrf_global *bvrf, int sd);
+ssize_t bfd_recv_ipv4(int sd, uint8_t *msgbuf, size_t msgbuflen, uint8_t *ttl,
+		      ifindex_t *ifindex, struct sockaddr_any *local,
+		      struct sockaddr_any *peer);
+ssize_t bfd_recv_ipv6(int sd, uint8_t *msgbuf, size_t msgbuflen, uint8_t *ttl,
+		      ifindex_t *ifindex, struct sockaddr_any *local,
+		      struct sockaddr_any *peer);
+int bp_udp_send(int sd, uint8_t ttl, uint8_t *data, size_t datalen,
+		struct sockaddr *to, socklen_t tolen);
+int bp_bfd_echo_in(struct bfd_vrf_global *bvrf, int sd, uint8_t *ttl,
+		   uint32_t *my_discr, uint64_t *my_rtt);
+#ifdef BFD_LINUX
+ssize_t bfd_recv_ipv4_fp(int sd, uint8_t *msgbuf, size_t msgbuflen,
+			 uint8_t *ttl, ifindex_t *ifindex,
+			 struct sockaddr_any *local, struct sockaddr_any *peer);
+void bfd_peer_mac_set(int sd, struct bfd_session *bfd,
+		      struct sockaddr_any *peer, struct interface *ifp);
+int bp_udp_send_fp(int sd, uint8_t *data, size_t datalen,
+		   struct bfd_session *bfd);
+ssize_t bfd_recv_fp_echo(int sd, uint8_t *msgbuf, size_t msgbuflen,
+			 uint8_t *ttl, ifindex_t *ifindex,
+			 struct sockaddr_any *local, struct sockaddr_any *peer);
+#endif
+
+/* socket related prototypes */
+static void bp_set_ipopts(int sd);
+static void bp_bind_ip(int sd, uint16_t port);
+static void bp_set_ipv6opts(int sd);
+static void bp_bind_ipv6(int sd, uint16_t port);
+
+
+/*
+ * Functions
+ */
+int _ptm_bfd_send(struct bfd_session *bs, uint16_t *port, const void *data,
+		  size_t datalen)
+{
+	struct sockaddr *sa;
+	struct sockaddr_in sin;
+	struct sockaddr_in6 sin6;
+	socklen_t slen;
+	ssize_t rv;
+	int sd = -1;
+
+	if (CHECK_FLAG(bs->flags, BFD_SESS_FLAG_IPV6)) {
+		memset(&sin6, 0, sizeof(sin6));
+		sin6.sin6_family = AF_INET6;
+		memcpy(&sin6.sin6_addr, &bs->key.peer, sizeof(sin6.sin6_addr));
+		if (bs->ifp && IN6_IS_ADDR_LINKLOCAL(&sin6.sin6_addr))
+			sin6.sin6_scope_id = bs->ifp->ifindex;
+
+		sin6.sin6_port =
+			(port) ? *port
+			       : (CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH))
+					 ? htons(BFD_DEF_MHOP_DEST_PORT)
+					 : htons(BFD_DEFDESTPORT);
+
+		sd = bs->sock;
+		sa = (struct sockaddr *)&sin6;
+		slen = sizeof(sin6);
+	} else {
+		memset(&sin, 0, sizeof(sin));
+		sin.sin_family = AF_INET;
+		memcpy(&sin.sin_addr, &bs->key.peer, sizeof(sin.sin_addr));
+		sin.sin_port =
+			(port) ? *port
+			       : (CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH))
+					 ? htons(BFD_DEF_MHOP_DEST_PORT)
+					 : htons(BFD_DEFDESTPORT);
+
+		sd = bs->sock;
+		sa = (struct sockaddr *)&sin;
+		slen = sizeof(sin);
+	}
+
+#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
+	sa->sa_len = slen;
+#endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
+	rv = sendto(sd, data, datalen, 0, sa, slen);
+	if (rv <= 0) {
+		if (bglobal.debug_network)
+			zlog_debug("packet-send: send failure: %s",
+				   strerror(errno));
+		return -1;
+	}
+	if (rv < (ssize_t)datalen) {
+		if (bglobal.debug_network)
+			zlog_debug("packet-send: send partial: %s",
+				   strerror(errno));
+	}
+
+	return 0;
+}
+
+#ifdef BFD_LINUX
+/*
+ * Compute the UDP checksum.
+ *
+ * Checksum is not set in the packet, just computed.
+ *
+ * pkt
+ *    Packet, fully filled out except for checksum field.
+ *
+ * pktsize
+ *    sizeof(*pkt)
+ *
+ * ip
+ *    IP address that pkt will be transmitted from and to.
+ *
+ * Returns:
+ *    Checksum in network byte order.
+ */
+static uint16_t bfd_pkt_checksum(struct udphdr *pkt, size_t pktsize,
+				 struct in6_addr *ip, sa_family_t family)
+{
+	uint16_t chksum;
+
+	pkt->check = 0;
+
+	if (family == AF_INET6) {
+		struct ipv6_ph ph = {};
+
+		memcpy(&ph.src, ip, sizeof(ph.src));
+		memcpy(&ph.dst, ip, sizeof(ph.dst));
+		ph.ulpl = htons(pktsize);
+		ph.next_hdr = IPPROTO_UDP;
+		chksum = in_cksum_with_ph6(&ph, pkt, pktsize);
+	} else {
+		struct ipv4_ph ph = {};
+
+		memcpy(&ph.src, ip, sizeof(ph.src));
+		memcpy(&ph.dst, ip, sizeof(ph.dst));
+		ph.proto = IPPROTO_UDP;
+		ph.len = htons(pktsize);
+		chksum = in_cksum_with_ph4(&ph, pkt, pktsize);
+	}
+
+	return chksum;
+}
+
+/*
+ * This routine creates the entire ECHO packet so that it will be looped
+ * in the forwarding plane of the peer router instead of going up the
+ * stack in BFD to be looped.  If we haven't learned the peers MAC yet
+ * no echo is sent.
+ *
+ * echo packet with src/dst IP equal to local IP
+ * dest MAC as peer's MAC
+ *
+ * currently support ipv4
+ */
+void ptm_bfd_echo_fp_snd(struct bfd_session *bfd)
+{
+	int sd;
+	struct bfd_vrf_global *bvrf = bfd_vrf_look_by_session(bfd);
+	int total_len = 0;
+	struct ethhdr *eth;
+	struct udphdr *uh;
+	struct iphdr *iph;
+	struct bfd_echo_pkt *beph;
+	static char sendbuff[100];
+	struct timeval time_sent;
+
+	if (!bvrf)
+		return;
+	if (!CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_MAC_SET))
+		return;
+	if (!CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_ECHO_ACTIVE))
+		SET_FLAG(bfd->flags, BFD_SESS_FLAG_ECHO_ACTIVE);
+
+	memset(sendbuff, 0, sizeof(sendbuff));
+
+	/* add eth hdr */
+	eth = (struct ethhdr *)(sendbuff);
+	memcpy(eth->h_source, bfd->ifp->hw_addr, sizeof(eth->h_source));
+	memcpy(eth->h_dest, bfd->peer_hw_addr, sizeof(eth->h_dest));
+
+	total_len += sizeof(struct ethhdr);
+
+	sd = bvrf->bg_echo;
+	eth->h_proto = htons(ETH_P_IP);
+
+	/* add ip hdr */
+	iph = (struct iphdr *)(sendbuff + sizeof(struct ethhdr));
+
+	iph->ihl = sizeof(struct ip) >> 2;
+	iph->version = IPVERSION;
+	iph->tos = IPTOS_PREC_INTERNETCONTROL;
+	iph->id = (uint16_t)frr_weak_random();
+	iph->ttl = BFD_TTL_VAL;
+	iph->protocol = IPPROTO_UDP;
+	memcpy(&iph->saddr, &bfd->local_address.sa_sin.sin_addr,
+	       sizeof(bfd->local_address.sa_sin.sin_addr));
+	memcpy(&iph->daddr, &bfd->local_address.sa_sin.sin_addr,
+	       sizeof(bfd->local_address.sa_sin.sin_addr));
+	total_len += sizeof(struct iphdr);
+
+	/* add udp hdr */
+	uh = (struct udphdr *)(sendbuff + sizeof(struct iphdr) +
+			       sizeof(struct ethhdr));
+	uh->source = htons(BFD_DEF_ECHO_PORT);
+	uh->dest = htons(BFD_DEF_ECHO_PORT);
+
+	total_len += sizeof(struct udphdr);
+
+	/* add bfd echo */
+	beph = (struct bfd_echo_pkt *)(sendbuff + sizeof(struct udphdr) +
+				       sizeof(struct iphdr) +
+				       sizeof(struct ethhdr));
+
+	beph->ver = BFD_ECHO_VERSION;
+	beph->len = BFD_ECHO_PKT_LEN;
+	beph->my_discr = htonl(bfd->discrs.my_discr);
+
+	/* RTT calculation: add starting time in packet */
+	monotime(&time_sent);
+	beph->time_sent_sec = htobe64(time_sent.tv_sec);
+	beph->time_sent_usec = htobe64(time_sent.tv_usec);
+
+	total_len += sizeof(struct bfd_echo_pkt);
+	uh->len =
+		htons(total_len - sizeof(struct iphdr) - sizeof(struct ethhdr));
+	uh->check = bfd_pkt_checksum(
+		uh, (total_len - sizeof(struct iphdr) - sizeof(struct ethhdr)),
+		(struct in6_addr *)&iph->saddr, AF_INET);
+
+	iph->tot_len = htons(total_len - sizeof(struct ethhdr));
+	iph->check = in_cksum((const void *)iph, sizeof(struct iphdr));
+
+	if (bp_udp_send_fp(sd, (uint8_t *)&sendbuff, total_len, bfd) == -1)
+		return;
+
+	bfd->stats.tx_echo_pkt++;
+}
+#endif
+
+void ptm_bfd_echo_snd(struct bfd_session *bfd)
+{
+	struct sockaddr *sa;
+	socklen_t salen;
+	int sd;
+	struct bfd_echo_pkt bep;
+	struct sockaddr_in sin;
+	struct sockaddr_in6 sin6;
+	struct bfd_vrf_global *bvrf = bfd_vrf_look_by_session(bfd);
+
+	if (!bvrf)
+		return;
+	if (!CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_ECHO_ACTIVE))
+		SET_FLAG(bfd->flags, BFD_SESS_FLAG_ECHO_ACTIVE);
+
+	memset(&bep, 0, sizeof(bep));
+	bep.ver = BFD_ECHO_VERSION;
+	bep.len = BFD_ECHO_PKT_LEN;
+	bep.my_discr = htonl(bfd->discrs.my_discr);
+
+	if (CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_IPV6)) {
+		if (bvrf->bg_echov6 == -1)
+			return;
+		sd = bvrf->bg_echov6;
+		memset(&sin6, 0, sizeof(sin6));
+		sin6.sin6_family = AF_INET6;
+		memcpy(&sin6.sin6_addr, &bfd->key.peer, sizeof(sin6.sin6_addr));
+		if (bfd->ifp && IN6_IS_ADDR_LINKLOCAL(&sin6.sin6_addr))
+			sin6.sin6_scope_id = bfd->ifp->ifindex;
+
+		sin6.sin6_port = htons(BFD_DEF_ECHO_PORT);
+#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
+		sin6.sin6_len = sizeof(sin6);
+#endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
+
+		sa = (struct sockaddr *)&sin6;
+		salen = sizeof(sin6);
+	} else {
+		sd = bvrf->bg_echo;
+		memset(&sin, 0, sizeof(sin));
+		sin.sin_family = AF_INET;
+		memcpy(&sin.sin_addr, &bfd->key.peer, sizeof(sin.sin_addr));
+		sin.sin_port = htons(BFD_DEF_ECHO_PORT);
+#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
+		sin.sin_len = sizeof(sin);
+#endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
+
+		sa = (struct sockaddr *)&sin;
+		salen = sizeof(sin);
+	}
+	if (bp_udp_send(sd, BFD_TTL_VAL, (uint8_t *)&bep, sizeof(bep), sa,
+			salen)
+	    == -1)
+		return;
+
+	bfd->stats.tx_echo_pkt++;
+}
+
+static int ptm_bfd_process_echo_pkt(struct bfd_vrf_global *bvrf, int s)
+{
+	struct bfd_session *bfd;
+	uint32_t my_discr = 0;
+	uint64_t my_rtt = 0;
+	uint8_t ttl = 0;
+
+	/* Receive and parse echo packet. */
+	if (bp_bfd_echo_in(bvrf, s, &ttl, &my_discr, &my_rtt) == -1)
+		return 0;
+
+	/* Your discriminator not zero - use it to find session */
+	bfd = bfd_id_lookup(my_discr);
+	if (bfd == NULL) {
+		if (bglobal.debug_network)
+			zlog_debug("echo-packet: no matching session (id:%u)",
+				   my_discr);
+		return -1;
+	}
+
+	if (!CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_ECHO_ACTIVE)) {
+		if (bglobal.debug_network)
+			zlog_debug("echo-packet: echo disabled [%s] (id:%u)",
+				   bs_to_string(bfd), my_discr);
+		return -1;
+	}
+
+	/* RTT Calculation: add current RTT to samples */
+	if (my_rtt != 0) {
+		bfd->rtt[bfd->rtt_index] = my_rtt;
+		bfd->rtt_index++;
+		if (bfd->rtt_index >= BFD_RTT_SAMPLE)
+			bfd->rtt_index = 0;
+		if (bfd->rtt_valid < BFD_RTT_SAMPLE)
+			bfd->rtt_valid++;
+	}
+
+	bfd->stats.rx_echo_pkt++;
+
+	/* Compute detect time */
+	bfd->echo_detect_TO = bfd->remote_detect_mult * bfd->echo_xmt_TO;
+
+	/* Update echo receive timeout. */
+	if (bfd->echo_detect_TO > 0)
+		bfd_echo_recvtimer_update(bfd);
+
+	return 0;
+}
+
+void ptm_bfd_snd(struct bfd_session *bfd, int fbit)
+{
+	struct bfd_pkt cp = {};
+
+	/* Set fields according to section 6.5.7 */
+	cp.diag = bfd->local_diag;
+	BFD_SETVER(cp.diag, BFD_VERSION);
+	cp.flags = 0;
+	BFD_SETSTATE(cp.flags, bfd->ses_state);
+
+	if (CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_CBIT))
+		BFD_SETCBIT(cp.flags, BFD_CBIT);
+
+	BFD_SETDEMANDBIT(cp.flags, BFD_DEF_DEMAND);
+
+	/*
+	 * Polling and Final can't be set at the same time.
+	 *
+	 * RFC 5880, Section 6.5.
+	 */
+	BFD_SETFBIT(cp.flags, fbit);
+	if (fbit == 0)
+		BFD_SETPBIT(cp.flags, bfd->polling);
+
+	cp.detect_mult = bfd->detect_mult;
+	cp.len = BFD_PKT_LEN;
+	cp.discrs.my_discr = htonl(bfd->discrs.my_discr);
+	cp.discrs.remote_discr = htonl(bfd->discrs.remote_discr);
+	if (bfd->polling) {
+		cp.timers.desired_min_tx =
+			htonl(bfd->timers.desired_min_tx);
+		cp.timers.required_min_rx =
+			htonl(bfd->timers.required_min_rx);
+	} else {
+		/*
+		 * We can only announce current setting on poll, this
+		 * avoids timing mismatch with our peer and give it
+		 * the oportunity to learn. See `bs_final_handler` for
+		 * more information.
+		 */
+		cp.timers.desired_min_tx =
+			htonl(bfd->cur_timers.desired_min_tx);
+		cp.timers.required_min_rx =
+			htonl(bfd->cur_timers.required_min_rx);
+	}
+	cp.timers.required_min_echo = htonl(bfd->timers.required_min_echo_rx);
+
+	if (_ptm_bfd_send(bfd, NULL, &cp, BFD_PKT_LEN) != 0)
+		return;
+
+	bfd->stats.tx_ctrl_pkt++;
+}
+
+#ifdef BFD_LINUX
+/*
+ * receive the ipv4 echo packet that was loopback in the peers forwarding plane
+ */
+ssize_t bfd_recv_ipv4_fp(int sd, uint8_t *msgbuf, size_t msgbuflen,
+			 uint8_t *ttl, ifindex_t *ifindex,
+			 struct sockaddr_any *local, struct sockaddr_any *peer)
+{
+	ssize_t mlen;
+	struct sockaddr_ll msgaddr;
+	struct msghdr msghdr;
+	struct iovec iov[1];
+	uint16_t recv_checksum;
+	uint16_t checksum;
+	struct iphdr *ip;
+	struct udphdr *uh;
+
+	/* Prepare the recvmsg params. */
+	iov[0].iov_base = msgbuf;
+	iov[0].iov_len = msgbuflen;
+
+	memset(&msghdr, 0, sizeof(msghdr));
+	msghdr.msg_name = &msgaddr;
+	msghdr.msg_namelen = sizeof(msgaddr);
+	msghdr.msg_iov = iov;
+	msghdr.msg_iovlen = 1;
+
+	mlen = recvmsg(sd, &msghdr, MSG_DONTWAIT);
+	if (mlen == -1) {
+		if (errno != EAGAIN || errno != EWOULDBLOCK || errno != EINTR)
+			zlog_err("%s: recv failed: %s", __func__,
+				 strerror(errno));
+
+		return -1;
+	}
+
+	ip = (struct iphdr *)(msgbuf + sizeof(struct ethhdr));
+
+	/* verify ip checksum */
+	recv_checksum = ip->check;
+	ip->check = 0;
+	checksum = in_cksum((const void *)ip, sizeof(struct iphdr));
+	if (recv_checksum != checksum) {
+		if (bglobal.debug_network)
+			zlog_debug(
+				"%s: invalid iphdr checksum expected 0x%x rcvd 0x%x",
+				__func__, checksum, recv_checksum);
+		return -1;
+	}
+
+	*ttl = ip->ttl;
+	if (*ttl != 254) {
+		if (bglobal.debug_network)
+			zlog_debug("%s: invalid TTL: %u", __func__, *ttl);
+		return -1;
+	}
+
+	local->sa_sin.sin_family = AF_INET;
+	memcpy(&local->sa_sin.sin_addr, &ip->saddr, sizeof(ip->saddr));
+	peer->sa_sin.sin_family = AF_INET;
+	memcpy(&peer->sa_sin.sin_addr, &ip->daddr, sizeof(ip->daddr));
+
+	*ifindex = msgaddr.sll_ifindex;
+
+	/* verify udp checksum */
+	uh = (struct udphdr *)(msgbuf + sizeof(struct iphdr) +
+			       sizeof(struct ethhdr));
+	recv_checksum = uh->check;
+	uh->check = 0;
+	checksum = bfd_pkt_checksum(uh, ntohs(uh->len),
+				    (struct in6_addr *)&ip->saddr, AF_INET);
+	if (recv_checksum != checksum) {
+		if (bglobal.debug_network)
+			zlog_debug(
+				"%s: invalid udphdr checksum expected 0x%x rcvd 0x%x",
+				__func__, checksum, recv_checksum);
+		return -1;
+	}
+	return mlen;
+}
+#endif
+
+ssize_t bfd_recv_ipv4(int sd, uint8_t *msgbuf, size_t msgbuflen, uint8_t *ttl,
+		      ifindex_t *ifindex, struct sockaddr_any *local,
+		      struct sockaddr_any *peer)
+{
+	struct cmsghdr *cm;
+	ssize_t mlen;
+	struct sockaddr_in msgaddr;
+	struct msghdr msghdr;
+	struct iovec iov[1];
+	uint8_t cmsgbuf[255];
+
+	/* Prepare the recvmsg params. */
+	iov[0].iov_base = msgbuf;
+	iov[0].iov_len = msgbuflen;
+
+	memset(&msghdr, 0, sizeof(msghdr));
+	msghdr.msg_name = &msgaddr;
+	msghdr.msg_namelen = sizeof(msgaddr);
+	msghdr.msg_iov = iov;
+	msghdr.msg_iovlen = 1;
+	msghdr.msg_control = cmsgbuf;
+	msghdr.msg_controllen = sizeof(cmsgbuf);
+
+	mlen = recvmsg(sd, &msghdr, MSG_DONTWAIT);
+	if (mlen == -1) {
+		if (errno != EAGAIN)
+			zlog_err("ipv4-recv: recv failed: %s", strerror(errno));
+
+		return -1;
+	}
+
+	/* Get source address */
+	peer->sa_sin = *((struct sockaddr_in *)(msghdr.msg_name));
+
+	/* Get and check TTL */
+	for (cm = CMSG_FIRSTHDR(&msghdr); cm != NULL;
+	     cm = CMSG_NXTHDR(&msghdr, cm)) {
+		if (cm->cmsg_level != IPPROTO_IP)
+			continue;
+
+		switch (cm->cmsg_type) {
+#ifdef BFD_LINUX
+		case IP_TTL: {
+			uint32_t ttlval;
+
+			memcpy(&ttlval, CMSG_DATA(cm), sizeof(ttlval));
+			if (ttlval > 255) {
+				if (bglobal.debug_network)
+					zlog_debug("%s: invalid TTL: %u",
+						   __func__, ttlval);
+				return -1;
+			}
+			*ttl = ttlval;
+			break;
+		}
+
+		case IP_PKTINFO: {
+			struct in_pktinfo *pi =
+				(struct in_pktinfo *)CMSG_DATA(cm);
+
+			if (pi == NULL)
+				break;
+
+			local->sa_sin.sin_family = AF_INET;
+			local->sa_sin.sin_addr = pi->ipi_addr;
+#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
+			local->sa_sin.sin_len = sizeof(local->sa_sin);
+#endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
+
+			*ifindex = pi->ipi_ifindex;
+			break;
+		}
+#endif /* BFD_LINUX */
+#ifdef BFD_BSD
+		case IP_RECVTTL: {
+			memcpy(ttl, CMSG_DATA(cm), sizeof(*ttl));
+			break;
+		}
+
+		case IP_RECVDSTADDR: {
+			struct in_addr ia;
+
+			memcpy(&ia, CMSG_DATA(cm), sizeof(ia));
+			local->sa_sin.sin_family = AF_INET;
+			local->sa_sin.sin_addr = ia;
+#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
+			local->sa_sin.sin_len = sizeof(local->sa_sin);
+#endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
+			break;
+		}
+#endif /* BFD_BSD */
+
+		default:
+			/*
+			 * On *BSDs we expect to land here when skipping
+			 * the IP_RECVIF header. It will be handled by
+			 * getsockopt_ifindex() below.
+			 */
+			/* NOTHING */
+			break;
+		}
+	}
+
+	/* OS agnostic way of getting interface name. */
+	if (*ifindex == IFINDEX_INTERNAL)
+		*ifindex = getsockopt_ifindex(AF_INET, &msghdr);
+
+	return mlen;
+}
+
+ssize_t bfd_recv_ipv6(int sd, uint8_t *msgbuf, size_t msgbuflen, uint8_t *ttl,
+		      ifindex_t *ifindex, struct sockaddr_any *local,
+		      struct sockaddr_any *peer)
+{
+	struct cmsghdr *cm;
+	struct in6_pktinfo *pi6 = NULL;
+	ssize_t mlen;
+	uint32_t ttlval;
+	struct sockaddr_in6 msgaddr6;
+	struct msghdr msghdr6;
+	struct iovec iov[1];
+	uint8_t cmsgbuf6[255];
+
+	/* Prepare the recvmsg params. */
+	iov[0].iov_base = msgbuf;
+	iov[0].iov_len = msgbuflen;
+
+	memset(&msghdr6, 0, sizeof(msghdr6));
+	msghdr6.msg_name = &msgaddr6;
+	msghdr6.msg_namelen = sizeof(msgaddr6);
+	msghdr6.msg_iov = iov;
+	msghdr6.msg_iovlen = 1;
+	msghdr6.msg_control = cmsgbuf6;
+	msghdr6.msg_controllen = sizeof(cmsgbuf6);
+
+	mlen = recvmsg(sd, &msghdr6, MSG_DONTWAIT);
+	if (mlen == -1) {
+		if (errno != EAGAIN)
+			zlog_err("ipv6-recv: recv failed: %s", strerror(errno));
+
+		return -1;
+	}
+
+	/* Get source address */
+	peer->sa_sin6 = *((struct sockaddr_in6 *)(msghdr6.msg_name));
+
+	/* Get and check TTL */
+	for (cm = CMSG_FIRSTHDR(&msghdr6); cm != NULL;
+	     cm = CMSG_NXTHDR(&msghdr6, cm)) {
+		if (cm->cmsg_level != IPPROTO_IPV6)
+			continue;
+
+		if (cm->cmsg_type == IPV6_HOPLIMIT) {
+			memcpy(&ttlval, CMSG_DATA(cm), sizeof(ttlval));
+			if (ttlval > 255) {
+				if (bglobal.debug_network)
+					zlog_debug("%s: invalid TTL: %u",
+						   __func__, ttlval);
+				return -1;
+			}
+
+			*ttl = ttlval;
+		} else if (cm->cmsg_type == IPV6_PKTINFO) {
+			pi6 = (struct in6_pktinfo *)CMSG_DATA(cm);
+			if (pi6) {
+				local->sa_sin6.sin6_family = AF_INET6;
+				local->sa_sin6.sin6_addr = pi6->ipi6_addr;
+#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
+				local->sa_sin6.sin6_len = sizeof(local->sa_sin6);
+#endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
+
+				*ifindex = pi6->ipi6_ifindex;
+
+				/* Set scope ID for link local addresses. */
+				if (IN6_IS_ADDR_LINKLOCAL(
+					    &peer->sa_sin6.sin6_addr))
+					peer->sa_sin6.sin6_scope_id = *ifindex;
+				if (IN6_IS_ADDR_LINKLOCAL(
+					    &local->sa_sin6.sin6_addr))
+					local->sa_sin6.sin6_scope_id = *ifindex;
+			}
+		}
+	}
+
+	return mlen;
+}
+
+static void bfd_sd_reschedule(struct bfd_vrf_global *bvrf, int sd)
+{
+	if (sd == bvrf->bg_shop) {
+		EVENT_OFF(bvrf->bg_ev[0]);
+		event_add_read(master, bfd_recv_cb, bvrf, bvrf->bg_shop,
+			       &bvrf->bg_ev[0]);
+	} else if (sd == bvrf->bg_mhop) {
+		EVENT_OFF(bvrf->bg_ev[1]);
+		event_add_read(master, bfd_recv_cb, bvrf, bvrf->bg_mhop,
+			       &bvrf->bg_ev[1]);
+	} else if (sd == bvrf->bg_shop6) {
+		EVENT_OFF(bvrf->bg_ev[2]);
+		event_add_read(master, bfd_recv_cb, bvrf, bvrf->bg_shop6,
+			       &bvrf->bg_ev[2]);
+	} else if (sd == bvrf->bg_mhop6) {
+		EVENT_OFF(bvrf->bg_ev[3]);
+		event_add_read(master, bfd_recv_cb, bvrf, bvrf->bg_mhop6,
+			       &bvrf->bg_ev[3]);
+	} else if (sd == bvrf->bg_echo) {
+		EVENT_OFF(bvrf->bg_ev[4]);
+		event_add_read(master, bfd_recv_cb, bvrf, bvrf->bg_echo,
+			       &bvrf->bg_ev[4]);
+	} else if (sd == bvrf->bg_echov6) {
+		EVENT_OFF(bvrf->bg_ev[5]);
+		event_add_read(master, bfd_recv_cb, bvrf, bvrf->bg_echov6,
+			       &bvrf->bg_ev[5]);
+	}
+}
+
+PRINTFRR(6, 7)
+static void cp_debug(bool mhop, struct sockaddr_any *peer,
+		     struct sockaddr_any *local, ifindex_t ifindex,
+		     vrf_id_t vrfid, const char *fmt, ...)
+{
+	char buf[512], peerstr[128], localstr[128], portstr[64], vrfstr[64];
+	va_list vl;
+
+	/* Don't to any processing if debug is disabled. */
+	if (bglobal.debug_network == false)
+		return;
+
+	if (peer->sa_sin.sin_family)
+		snprintf(peerstr, sizeof(peerstr), " peer:%s", satostr(peer));
+	else
+		peerstr[0] = 0;
+
+	if (local->sa_sin.sin_family)
+		snprintf(localstr, sizeof(localstr), " local:%s",
+			 satostr(local));
+	else
+		localstr[0] = 0;
+
+	if (ifindex != IFINDEX_INTERNAL)
+		snprintf(portstr, sizeof(portstr), " port:%u", ifindex);
+	else
+		portstr[0] = 0;
+
+	if (vrfid != VRF_DEFAULT)
+		snprintf(vrfstr, sizeof(vrfstr), " vrf:%u", vrfid);
+	else
+		vrfstr[0] = 0;
+
+	va_start(vl, fmt);
+	vsnprintf(buf, sizeof(buf), fmt, vl);
+	va_end(vl);
+
+	zlog_debug("control-packet: %s [mhop:%s%s%s%s%s]", buf,
+		   mhop ? "yes" : "no", peerstr, localstr, portstr, vrfstr);
+}
+
+static bool bfd_check_auth(const struct bfd_session *bfd,
+			   const struct bfd_pkt *cp)
+{
+	if (CHECK_FLAG(cp->flags, BFD_ABIT)) {
+		/* RFC5880 4.1: Authentication Section is present. */
+		struct bfd_auth *auth = (struct bfd_auth *)(cp + 1);
+		uint16_t pkt_auth_type = ntohs(auth->type);
+
+		if (cp->len < BFD_PKT_LEN + sizeof(struct bfd_auth))
+			return false;
+
+		if (cp->len < BFD_PKT_LEN + auth->length)
+			return false;
+
+		switch (pkt_auth_type) {
+		case BFD_AUTH_NULL:
+			return false;
+		case BFD_AUTH_SIMPLE:
+			/* RFC5880 6.7: To be finshed. */
+			return false;
+		case BFD_AUTH_CRYPTOGRAPHIC:
+			/* RFC5880 6.7: To be finshed. */
+			return false;
+		default:
+			/* RFC5880 6.7: To be finshed. */
+			return false;
+		}
+	}
+	return true;
+}
+
+void bfd_recv_cb(struct event *t)
+{
+	int sd = EVENT_FD(t);
+	struct bfd_session *bfd;
+	struct bfd_pkt *cp;
+	bool is_mhop;
+	ssize_t mlen = 0;
+	uint8_t ttl = 0;
+	vrf_id_t vrfid;
+	ifindex_t ifindex = IFINDEX_INTERNAL;
+	struct sockaddr_any local, peer;
+	uint8_t msgbuf[1516];
+	struct interface *ifp = NULL;
+	struct bfd_vrf_global *bvrf = EVENT_ARG(t);
+
+	/* Schedule next read. */
+	bfd_sd_reschedule(bvrf, sd);
+
+	/* Handle echo packets. */
+	if (sd == bvrf->bg_echo || sd == bvrf->bg_echov6) {
+		ptm_bfd_process_echo_pkt(bvrf, sd);
+		return;
+	}
+
+	/* Sanitize input/output. */
+	memset(&local, 0, sizeof(local));
+	memset(&peer, 0, sizeof(peer));
+
+	/* Handle control packets. */
+	is_mhop = false;
+	if (sd == bvrf->bg_shop || sd == bvrf->bg_mhop) {
+		is_mhop = sd == bvrf->bg_mhop;
+		mlen = bfd_recv_ipv4(sd, msgbuf, sizeof(msgbuf), &ttl, &ifindex,
+				     &local, &peer);
+	} else if (sd == bvrf->bg_shop6 || sd == bvrf->bg_mhop6) {
+		is_mhop = sd == bvrf->bg_mhop6;
+		mlen = bfd_recv_ipv6(sd, msgbuf, sizeof(msgbuf), &ttl, &ifindex,
+				     &local, &peer);
+	}
+
+	/*
+	 * With netns backend, we have a separate socket in each VRF. It means
+	 * that bvrf here is correct and we believe the bvrf->vrf->vrf_id.
+	 * With VRF-lite backend, we have a single socket in the default VRF.
+	 * It means that we can't believe the bvrf->vrf->vrf_id. But in
+	 * VRF-lite, the ifindex is globally unique, so we can retrieve the
+	 * correct vrf_id from the interface.
+	 */
+	vrfid = bvrf->vrf->vrf_id;
+	if (ifindex) {
+		ifp = if_lookup_by_index(ifindex, vrfid);
+		if (ifp)
+			vrfid = ifp->vrf->vrf_id;
+	}
+
+	/* Implement RFC 5880 6.8.6 */
+	if (mlen < BFD_PKT_LEN) {
+		cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
+			 "too small (%zd bytes)", mlen);
+		return;
+	}
+
+	/* Validate single hop packet TTL. */
+	if ((!is_mhop) && (ttl != BFD_TTL_VAL)) {
+		cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
+			 "invalid TTL: %d expected %d", ttl, BFD_TTL_VAL);
+		return;
+	}
+
+	/*
+	 * Parse the control header for inconsistencies:
+	 * - Invalid version;
+	 * - Bad multiplier configuration;
+	 * - Short packets;
+	 * - Invalid discriminator;
+	 */
+	cp = (struct bfd_pkt *)(msgbuf);
+	if (BFD_GETVER(cp->diag) != BFD_VERSION) {
+		cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
+			 "bad version %d", BFD_GETVER(cp->diag));
+		return;
+	}
+
+	if (cp->detect_mult == 0) {
+		cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
+			 "detect multiplier set to zero");
+		return;
+	}
+
+	if ((cp->len < BFD_PKT_LEN) || (cp->len > mlen)) {
+		cp_debug(is_mhop, &peer, &local, ifindex, vrfid, "too small");
+		return;
+	}
+
+	if (cp->discrs.my_discr == 0) {
+		cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
+			 "'my discriminator' is zero");
+		return;
+	}
+
+	/* Find the session that this packet belongs. */
+	bfd = ptm_bfd_sess_find(cp, &peer, &local, ifp, vrfid, is_mhop);
+	if (bfd == NULL) {
+		cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
+			 "no session found");
+		return;
+	}
+	/*
+	 * We may have a situation where received packet is on wrong vrf
+	 */
+	if (bfd && bfd->vrf && bfd->vrf->vrf_id != vrfid) {
+		cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
+			 "wrong vrfid.");
+		return;
+	}
+
+	/* Ensure that existing good sessions are not overridden. */
+	if (!cp->discrs.remote_discr && bfd->ses_state != PTM_BFD_DOWN &&
+	    bfd->ses_state != PTM_BFD_ADM_DOWN) {
+		cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
+			 "'remote discriminator' is zero, not overridden");
+		return;
+	}
+
+	/*
+	 * Multi hop: validate packet TTL.
+	 * Single hop: set local address that received the packet.
+	 *             set peers mac address for echo packets
+	 */
+	if (is_mhop) {
+		if (ttl < bfd->mh_ttl) {
+			cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
+				 "exceeded max hop count (expected %d, got %d)",
+				 bfd->mh_ttl, ttl);
+			return;
+		}
+	} else {
+
+		if (bfd->local_address.sa_sin.sin_family == AF_UNSPEC)
+			bfd->local_address = local;
+#ifdef BFD_LINUX
+		if (ifp)
+			bfd_peer_mac_set(sd, bfd, &peer, ifp);
+#endif
+	}
+
+	bfd->stats.rx_ctrl_pkt++;
+
+	/*
+	 * If no interface was detected, save the interface where the
+	 * packet came in.
+	 */
+	if (!is_mhop && bfd->ifp == NULL)
+		bfd->ifp = ifp;
+
+	/* Log remote discriminator changes. */
+	if ((bfd->discrs.remote_discr != 0)
+	    && (bfd->discrs.remote_discr != ntohl(cp->discrs.my_discr)))
+		cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
+			 "remote discriminator mismatch (expected %u, got %u)",
+			 bfd->discrs.remote_discr, ntohl(cp->discrs.my_discr));
+
+	bfd->discrs.remote_discr = ntohl(cp->discrs.my_discr);
+
+	/* Check authentication. */
+	if (!bfd_check_auth(bfd, cp)) {
+		cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
+			 "Authentication failed");
+		return;
+	}
+
+	/* Save remote diagnostics before state switch. */
+	bfd->remote_diag = cp->diag & BFD_DIAGMASK;
+
+	/* Update remote timers settings. */
+	bfd->remote_timers.desired_min_tx = ntohl(cp->timers.desired_min_tx);
+	bfd->remote_timers.required_min_rx = ntohl(cp->timers.required_min_rx);
+	bfd->remote_timers.required_min_echo =
+		ntohl(cp->timers.required_min_echo);
+	bfd->remote_detect_mult = cp->detect_mult;
+
+	if (BFD_GETCBIT(cp->flags))
+		bfd->remote_cbit = 1;
+	else
+		bfd->remote_cbit = 0;
+
+	/* State switch from section 6.2. */
+	bs_state_handler(bfd, BFD_GETSTATE(cp->flags));
+
+	/* RFC 5880, Section 6.5: handle POLL/FINAL negotiation sequence. */
+	if (bfd->polling && BFD_GETFBIT(cp->flags)) {
+		/* Disable polling. */
+		bfd->polling = 0;
+
+		/* Handle poll finalization. */
+		bs_final_handler(bfd);
+	}
+
+	/*
+	 * Detection timeout calculation:
+	 * The minimum detection timeout is the remote detection
+	 * multipler (number of packets to be missed) times the agreed
+	 * transmission interval.
+	 *
+	 * RFC 5880, Section 6.8.4.
+	 */
+	if (bfd->cur_timers.required_min_rx > bfd->remote_timers.desired_min_tx)
+		bfd->detect_TO = bfd->remote_detect_mult
+				 * bfd->cur_timers.required_min_rx;
+	else
+		bfd->detect_TO = bfd->remote_detect_mult
+				 * bfd->remote_timers.desired_min_tx;
+
+	/* Apply new receive timer immediately. */
+	bfd_recvtimer_update(bfd);
+
+	/* Handle echo timers changes. */
+	bs_echo_timer_handler(bfd);
+
+	/*
+	 * We've received a packet with the POLL bit set, we must send
+	 * a control packet back with the FINAL bit set.
+	 *
+	 * RFC 5880, Section 6.5.
+	 */
+	if (BFD_GETPBIT(cp->flags)) {
+		/* We are finalizing a poll negotiation. */
+		bs_final_handler(bfd);
+
+		/* Send the control packet with the final bit immediately. */
+		ptm_bfd_snd(bfd, 1);
+	}
+}
+
+/*
+ * bp_bfd_echo_in: proccesses an BFD echo packet. On TTL == BFD_TTL_VAL
+ * the packet is looped back or returns the my discriminator ID along
+ * with the TTL.
+ *
+ * Returns -1 on error or loopback or 0 on success.
+ */
+int bp_bfd_echo_in(struct bfd_vrf_global *bvrf, int sd, uint8_t *ttl,
+		   uint32_t *my_discr, uint64_t *my_rtt)
+{
+	struct bfd_echo_pkt *bep;
+	ssize_t rlen;
+	struct sockaddr_any local, peer;
+	ifindex_t ifindex = IFINDEX_INTERNAL;
+	vrf_id_t vrfid = VRF_DEFAULT;
+	uint8_t msgbuf[1516];
+	size_t bfd_offset = 0;
+
+	if (sd == bvrf->bg_echo) {
+#ifdef BFD_LINUX
+		rlen = bfd_recv_ipv4_fp(sd, msgbuf, sizeof(msgbuf), ttl,
+					&ifindex, &local, &peer);
+
+		/* silently drop echo packet that is looped in fastpath but
+		 * still comes up to BFD
+		 */
+		if (rlen == -1)
+			return -1;
+		bfd_offset = sizeof(struct udphdr) + sizeof(struct iphdr) +
+			     sizeof(struct ethhdr);
+#else
+		rlen = bfd_recv_ipv4(sd, msgbuf, sizeof(msgbuf), ttl, &ifindex,
+				     &local, &peer);
+		bfd_offset = 0;
+#endif
+	} else {
+		rlen = bfd_recv_ipv6(sd, msgbuf, sizeof(msgbuf), ttl, &ifindex,
+				     &local, &peer);
+		bfd_offset = 0;
+	}
+
+	/* Short packet, better not risk reading it. */
+	if (rlen < (ssize_t)sizeof(*bep)) {
+		cp_debug(false, &peer, &local, ifindex, vrfid,
+			 "small echo packet");
+		return -1;
+	}
+
+	/* Test for loopback for ipv6, ipv4 is looped in forwarding plane */
+	if ((*ttl == BFD_TTL_VAL) && (sd == bvrf->bg_echov6)) {
+		bp_udp_send(sd, *ttl - 1, msgbuf, rlen,
+			    (struct sockaddr *)&peer,
+			    (sd == bvrf->bg_echo) ? sizeof(peer.sa_sin)
+						    : sizeof(peer.sa_sin6));
+		return -1;
+	}
+
+	/* Read my discriminator from BFD Echo packet. */
+	bep = (struct bfd_echo_pkt *)(msgbuf + bfd_offset);
+	*my_discr = ntohl(bep->my_discr);
+	if (*my_discr == 0) {
+		cp_debug(false, &peer, &local, ifindex, vrfid,
+			 "invalid echo packet discriminator (zero)");
+		return -1;
+	}
+
+#ifdef BFD_LINUX
+	/* RTT Calculation: determine RTT time of IPv4 echo pkt */
+	if (sd == bvrf->bg_echo) {
+		struct timeval time_sent = {0, 0};
+
+		time_sent.tv_sec = be64toh(bep->time_sent_sec);
+		time_sent.tv_usec = be64toh(bep->time_sent_usec);
+		*my_rtt = monotime_since(&time_sent, NULL);
+	}
+#endif
+
+	return 0;
+}
+
+#ifdef BFD_LINUX
+/*
+ * send a bfd packet with src/dst same IP so that the peer will receive
+ * the packet and forward it back to sender in the forwarding plane
+ */
+int bp_udp_send_fp(int sd, uint8_t *data, size_t datalen,
+		   struct bfd_session *bfd)
+{
+	ssize_t wlen;
+	struct msghdr msg = {0};
+	struct iovec iov[1];
+	uint8_t msgctl[255];
+	struct sockaddr_ll sadr_ll = {0};
+
+	sadr_ll.sll_ifindex = bfd->ifp->ifindex;
+	sadr_ll.sll_halen = ETH_ALEN;
+	memcpy(sadr_ll.sll_addr, bfd->peer_hw_addr, sizeof(bfd->peer_hw_addr));
+	sadr_ll.sll_protocol = htons(ETH_P_IP);
+
+	/* Prepare message data. */
+	iov[0].iov_base = data;
+	iov[0].iov_len = datalen;
+
+	memset(msgctl, 0, sizeof(msgctl));
+	msg.msg_name = &sadr_ll;
+	msg.msg_namelen = sizeof(sadr_ll);
+	msg.msg_iov = iov;
+	msg.msg_iovlen = 1;
+
+	/* Send echo to peer */
+	wlen = sendmsg(sd, &msg, 0);
+
+	if (wlen <= 0) {
+		if (bglobal.debug_network)
+			zlog_debug("%s: loopback failure: (%d) %s", __func__,
+				   errno, strerror(errno));
+		return -1;
+	} else if (wlen < (ssize_t)datalen) {
+		if (bglobal.debug_network)
+			zlog_debug("%s: partial send: %zd expected %zu",
+				   __func__, wlen, datalen);
+		return -1;
+	}
+
+	return 0;
+}
+#endif
+
+int bp_udp_send(int sd, uint8_t ttl, uint8_t *data, size_t datalen,
+		struct sockaddr *to, socklen_t tolen)
+{
+	struct cmsghdr *cmsg;
+	ssize_t wlen;
+	int ttlval = ttl;
+	bool is_ipv6 = to->sa_family == AF_INET6;
+	struct msghdr msg;
+	struct iovec iov[1];
+	uint8_t msgctl[255];
+
+	/* Prepare message data. */
+	iov[0].iov_base = data;
+	iov[0].iov_len = datalen;
+
+	memset(&msg, 0, sizeof(msg));
+	memset(msgctl, 0, sizeof(msgctl));
+	msg.msg_name = to;
+	msg.msg_namelen = tolen;
+	msg.msg_iov = iov;
+	msg.msg_iovlen = 1;
+
+	/* Prepare the packet TTL information. */
+	if (ttl > 0) {
+		/* Use ancillary data. */
+		msg.msg_control = msgctl;
+		msg.msg_controllen = CMSG_LEN(sizeof(ttlval));
+
+		/* Configure the ancillary data. */
+		cmsg = CMSG_FIRSTHDR(&msg);
+		cmsg->cmsg_len = CMSG_LEN(sizeof(ttlval));
+		if (is_ipv6) {
+			cmsg->cmsg_level = IPPROTO_IPV6;
+			cmsg->cmsg_type = IPV6_HOPLIMIT;
+		} else {
+#ifdef BFD_LINUX
+			cmsg->cmsg_level = IPPROTO_IP;
+			cmsg->cmsg_type = IP_TTL;
+#else
+			/* FreeBSD does not support TTL in ancillary data. */
+			msg.msg_control = NULL;
+			msg.msg_controllen = 0;
+
+			bp_set_ttl(sd, ttl);
+#endif /* BFD_BSD */
+		}
+		memcpy(CMSG_DATA(cmsg), &ttlval, sizeof(ttlval));
+	}
+
+	/* Send echo back. */
+	wlen = sendmsg(sd, &msg, 0);
+	if (wlen <= 0) {
+		if (bglobal.debug_network)
+			zlog_debug("%s: loopback failure: (%d) %s", __func__,
+				   errno, strerror(errno));
+		return -1;
+	} else if (wlen < (ssize_t)datalen) {
+		if (bglobal.debug_network)
+			zlog_debug("%s: partial send: %zd expected %zu",
+				   __func__, wlen, datalen);
+		return -1;
+	}
+
+	return 0;
+}
+
+
+/*
+ * Sockets creation.
+ */
+
+
+/*
+ * IPv4 sockets
+ */
+int bp_set_ttl(int sd, uint8_t value)
+{
+	int ttl = value;
+
+	if (setsockopt(sd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)) == -1) {
+		zlog_warn("%s: setsockopt(IP_TTL, %d): %s", __func__, value,
+			  strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
+int bp_set_tos(int sd, uint8_t value)
+{
+	int tos = value;
+
+	if (setsockopt(sd, IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) == -1) {
+		zlog_warn("%s: setsockopt(IP_TOS, %d): %s", __func__, value,
+			  strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
+static bool bp_set_reuse_addr(int sd)
+{
+	int one = 1;
+
+	if (setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) == -1) {
+		zlog_warn("%s: setsockopt(SO_REUSEADDR, %d): %s", __func__, one,
+			  strerror(errno));
+		return false;
+	}
+	return true;
+}
+
+static bool bp_set_reuse_port(int sd)
+{
+	int one = 1;
+
+	if (setsockopt(sd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one)) == -1) {
+		zlog_warn("%s: setsockopt(SO_REUSEPORT, %d): %s", __func__, one,
+			  strerror(errno));
+		return false;
+	}
+	return true;
+}
+
+
+static void bp_set_ipopts(int sd)
+{
+	int rcvttl = BFD_RCV_TTL_VAL;
+
+	if (!bp_set_reuse_addr(sd))
+		zlog_fatal("set-reuse-addr: failed");
+
+	if (!bp_set_reuse_port(sd))
+		zlog_fatal("set-reuse-port: failed");
+
+	if (bp_set_ttl(sd, BFD_TTL_VAL) != 0)
+		zlog_fatal("set-ipopts: TTL configuration failed");
+
+	if (setsockopt(sd, IPPROTO_IP, IP_RECVTTL, &rcvttl, sizeof(rcvttl))
+	    == -1)
+		zlog_fatal("set-ipopts: setsockopt(IP_RECVTTL, %d): %s", rcvttl,
+			   strerror(errno));
+
+#ifdef BFD_LINUX
+	int pktinfo = BFD_PKT_INFO_VAL;
+
+	/* Figure out address and interface to do the peer matching. */
+	if (setsockopt(sd, IPPROTO_IP, IP_PKTINFO, &pktinfo, sizeof(pktinfo))
+	    == -1)
+		zlog_fatal("set-ipopts: setsockopt(IP_PKTINFO, %d): %s",
+			   pktinfo, strerror(errno));
+#endif /* BFD_LINUX */
+#ifdef BFD_BSD
+	int yes = 1;
+
+	/* Find out our address for peer matching. */
+	if (setsockopt(sd, IPPROTO_IP, IP_RECVDSTADDR, &yes, sizeof(yes)) == -1)
+		zlog_fatal("set-ipopts: setsockopt(IP_RECVDSTADDR, %d): %s",
+			   yes, strerror(errno));
+
+	/* Find out interface where the packet came in. */
+	if (setsockopt_ifindex(AF_INET, sd, yes) == -1)
+		zlog_fatal("set-ipopts: setsockopt_ipv4_ifindex(%d): %s", yes,
+			   strerror(errno));
+#endif /* BFD_BSD */
+}
+
+static void bp_bind_ip(int sd, uint16_t port)
+{
+	struct sockaddr_in sin;
+
+	memset(&sin, 0, sizeof(sin));
+	sin.sin_family = AF_INET;
+	sin.sin_addr.s_addr = htonl(INADDR_ANY);
+	sin.sin_port = htons(port);
+	if (bind(sd, (struct sockaddr *)&sin, sizeof(sin)) == -1)
+		zlog_fatal("bind-ip: bind: %s", strerror(errno));
+}
+
+int bp_udp_shop(const struct vrf *vrf)
+{
+	int sd;
+
+	frr_with_privs(&bglobal.bfdd_privs) {
+		sd = vrf_socket(AF_INET, SOCK_DGRAM, PF_UNSPEC, vrf->vrf_id,
+				vrf->name);
+	}
+	if (sd == -1)
+		zlog_fatal("udp-shop: socket: %s", strerror(errno));
+
+	bp_set_ipopts(sd);
+	bp_bind_ip(sd, BFD_DEFDESTPORT);
+	return sd;
+}
+
+int bp_udp_mhop(const struct vrf *vrf)
+{
+	int sd;
+
+	frr_with_privs(&bglobal.bfdd_privs) {
+		sd = vrf_socket(AF_INET, SOCK_DGRAM, PF_UNSPEC, vrf->vrf_id,
+				vrf->name);
+	}
+	if (sd == -1)
+		zlog_fatal("udp-mhop: socket: %s", strerror(errno));
+
+	bp_set_ipopts(sd);
+	bp_bind_ip(sd, BFD_DEF_MHOP_DEST_PORT);
+
+	return sd;
+}
+
+int bp_peer_socket(const struct bfd_session *bs)
+{
+	int sd, pcount;
+	struct sockaddr_in sin;
+	static int srcPort = BFD_SRCPORTINIT;
+	const char *device_to_bind = NULL;
+
+	if (bs->key.ifname[0])
+		device_to_bind = (const char *)bs->key.ifname;
+	else if ((!vrf_is_backend_netns() && bs->vrf->vrf_id != VRF_DEFAULT)
+		 || ((CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH)
+		      && bs->key.vrfname[0])))
+		device_to_bind = (const char *)bs->key.vrfname;
+
+	frr_with_privs(&bglobal.bfdd_privs) {
+		sd = vrf_socket(AF_INET, SOCK_DGRAM, PF_UNSPEC,
+				bs->vrf->vrf_id, device_to_bind);
+	}
+	if (sd == -1) {
+		zlog_err("ipv4-new: failed to create socket: %s",
+			 strerror(errno));
+		return -1;
+	}
+
+	/* Set TTL to 255 for all transmitted packets */
+	if (bp_set_ttl(sd, BFD_TTL_VAL) != 0) {
+		close(sd);
+		return -1;
+	}
+
+	/* Set TOS to CS6 for all transmitted packets */
+	if (bp_set_tos(sd, BFD_TOS_VAL) != 0) {
+		close(sd);
+		return -1;
+	}
+
+	/* Find an available source port in the proper range */
+	memset(&sin, 0, sizeof(sin));
+	sin.sin_family = AF_INET;
+#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
+	sin.sin_len = sizeof(sin);
+#endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
+	memcpy(&sin.sin_addr, &bs->key.local, sizeof(sin.sin_addr));
+
+	pcount = 0;
+	do {
+		if ((++pcount) > (BFD_SRCPORTMAX - BFD_SRCPORTINIT)) {
+			/* Searched all ports, none available */
+			zlog_err("ipv4-new: failed to bind port: %s",
+				 strerror(errno));
+			close(sd);
+			return -1;
+		}
+		if (srcPort >= BFD_SRCPORTMAX)
+			srcPort = BFD_SRCPORTINIT;
+		sin.sin_port = htons(srcPort++);
+	} while (bind(sd, (struct sockaddr *)&sin, sizeof(sin)) < 0);
+
+	return sd;
+}
+
+
+/*
+ * IPv6 sockets
+ */
+
+int bp_peer_socketv6(const struct bfd_session *bs)
+{
+	int sd, pcount;
+	struct sockaddr_in6 sin6;
+	static int srcPort = BFD_SRCPORTINIT;
+	const char *device_to_bind = NULL;
+
+	if (bs->key.ifname[0])
+		device_to_bind = (const char *)bs->key.ifname;
+	else if ((!vrf_is_backend_netns() && bs->vrf->vrf_id != VRF_DEFAULT)
+		 || ((CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH)
+		      && bs->key.vrfname[0])))
+		device_to_bind = (const char *)bs->key.vrfname;
+
+	frr_with_privs(&bglobal.bfdd_privs) {
+		sd = vrf_socket(AF_INET6, SOCK_DGRAM, PF_UNSPEC,
+				bs->vrf->vrf_id, device_to_bind);
+	}
+	if (sd == -1) {
+		zlog_err("ipv6-new: failed to create socket: %s",
+			 strerror(errno));
+		return -1;
+	}
+
+	/* Set TTL to 255 for all transmitted packets */
+	if (bp_set_ttlv6(sd, BFD_TTL_VAL) != 0) {
+		close(sd);
+		return -1;
+	}
+
+	/* Set TOS to CS6 for all transmitted packets */
+	if (bp_set_tosv6(sd, BFD_TOS_VAL) != 0) {
+		close(sd);
+		return -1;
+	}
+
+	/* Find an available source port in the proper range */
+	memset(&sin6, 0, sizeof(sin6));
+	sin6.sin6_family = AF_INET6;
+#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
+	sin6.sin6_len = sizeof(sin6);
+#endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
+	memcpy(&sin6.sin6_addr, &bs->key.local, sizeof(sin6.sin6_addr));
+	if (bs->ifp && IN6_IS_ADDR_LINKLOCAL(&sin6.sin6_addr))
+		sin6.sin6_scope_id = bs->ifp->ifindex;
+
+	pcount = 0;
+	do {
+		if ((++pcount) > (BFD_SRCPORTMAX - BFD_SRCPORTINIT)) {
+			/* Searched all ports, none available */
+			zlog_err("ipv6-new: failed to bind port: %s",
+				 strerror(errno));
+			close(sd);
+			return -1;
+		}
+		if (srcPort >= BFD_SRCPORTMAX)
+			srcPort = BFD_SRCPORTINIT;
+		sin6.sin6_port = htons(srcPort++);
+	} while (bind(sd, (struct sockaddr *)&sin6, sizeof(sin6)) < 0);
+
+	return sd;
+}
+
+int bp_set_ttlv6(int sd, uint8_t value)
+{
+	int ttl = value;
+
+	if (setsockopt(sd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl))
+	    == -1) {
+		zlog_warn("set-ttlv6: setsockopt(IPV6_UNICAST_HOPS, %d): %s",
+			  value, strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
+int bp_set_tosv6(int sd, uint8_t value)
+{
+	int tos = value;
+
+	if (setsockopt(sd, IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos))
+	    == -1) {
+		zlog_warn("set-tosv6: setsockopt(IPV6_TCLASS, %d): %s", value,
+			  strerror(errno));
+		return -1;
+	}
+
+	return 0;
+}
+
+static void bp_set_ipv6opts(int sd)
+{
+	int ipv6_pktinfo = BFD_IPV6_PKT_INFO_VAL;
+	int ipv6_only = BFD_IPV6_ONLY_VAL;
+
+	if (!bp_set_reuse_addr(sd))
+		zlog_fatal("set-reuse-addr: failed");
+
+	if (!bp_set_reuse_port(sd))
+		zlog_fatal("set-reuse-port: failed");
+
+	if (bp_set_ttlv6(sd, BFD_TTL_VAL) == -1)
+		zlog_fatal(
+			"set-ipv6opts: setsockopt(IPV6_UNICAST_HOPS, %d): %s",
+			BFD_TTL_VAL, strerror(errno));
+
+	if (setsockopt_ipv6_hoplimit(sd, BFD_RCV_TTL_VAL) == -1)
+		zlog_fatal("set-ipv6opts: setsockopt(IPV6_HOPLIMIT, %d): %s",
+			   BFD_RCV_TTL_VAL, strerror(errno));
+
+	if (setsockopt_ipv6_pktinfo(sd, ipv6_pktinfo) == -1)
+		zlog_fatal("set-ipv6opts: setsockopt(IPV6_PKTINFO, %d): %s",
+			   ipv6_pktinfo, strerror(errno));
+
+	if (setsockopt(sd, IPPROTO_IPV6, IPV6_V6ONLY, &ipv6_only,
+		       sizeof(ipv6_only))
+	    == -1)
+		zlog_fatal("set-ipv6opts: setsockopt(IPV6_V6ONLY, %d): %s",
+			   ipv6_only, strerror(errno));
+}
+
+static void bp_bind_ipv6(int sd, uint16_t port)
+{
+	struct sockaddr_in6 sin6;
+
+	memset(&sin6, 0, sizeof(sin6));
+	sin6.sin6_family = AF_INET6;
+	sin6.sin6_addr = in6addr_any;
+	sin6.sin6_port = htons(port);
+#ifdef HAVE_STRUCT_SOCKADDR_SA_LEN
+	sin6.sin6_len = sizeof(sin6);
+#endif /* HAVE_STRUCT_SOCKADDR_SA_LEN */
+	if (bind(sd, (struct sockaddr *)&sin6, sizeof(sin6)) == -1)
+		zlog_fatal("bind-ipv6: bind: %s", strerror(errno));
+}
+
+int bp_udp6_shop(const struct vrf *vrf)
+{
+	int sd;
+
+	frr_with_privs(&bglobal.bfdd_privs) {
+		sd = vrf_socket(AF_INET6, SOCK_DGRAM, PF_UNSPEC, vrf->vrf_id,
+				vrf->name);
+	}
+	if (sd == -1) {
+		if (errno != EAFNOSUPPORT)
+			zlog_fatal("udp6-shop: socket: %s", strerror(errno));
+		else
+			zlog_warn("udp6-shop: V6 is not supported, continuing");
+
+		return -1;
+	}
+
+	bp_set_ipv6opts(sd);
+	bp_bind_ipv6(sd, BFD_DEFDESTPORT);
+
+	return sd;
+}
+
+int bp_udp6_mhop(const struct vrf *vrf)
+{
+	int sd;
+
+	frr_with_privs(&bglobal.bfdd_privs) {
+		sd = vrf_socket(AF_INET6, SOCK_DGRAM, PF_UNSPEC, vrf->vrf_id,
+				vrf->name);
+	}
+	if (sd == -1) {
+		if (errno != EAFNOSUPPORT)
+			zlog_fatal("udp6-mhop: socket: %s", strerror(errno));
+		else
+			zlog_warn("udp6-mhop: V6 is not supported, continuing");
+
+		return -1;
+	}
+
+	bp_set_ipv6opts(sd);
+	bp_bind_ipv6(sd, BFD_DEF_MHOP_DEST_PORT);
+
+	return sd;
+}
+
+#ifdef BFD_LINUX
+/* tcpdump -dd udp dst port 3785 */
+struct sock_filter my_filterudp[] = {
+	{0x28, 0, 0, 0x0000000c}, {0x15, 0, 8, 0x00000800},
+	{0x30, 0, 0, 0x00000017}, {0x15, 0, 6, 0x00000011},
+	{0x28, 0, 0, 0x00000014}, {0x45, 4, 0, 0x00001fff},
+	{0xb1, 0, 0, 0x0000000e}, {0x48, 0, 0, 0x00000010},
+	{0x15, 0, 1, 0x00000ec9}, {0x6, 0, 0, 0x00040000},
+	{0x6, 0, 0, 0x00000000},
+};
+
+#define MY_FILTER_LENGTH 11
+
+int bp_echo_socket(const struct vrf *vrf)
+{
+	int s;
+
+	frr_with_privs (&bglobal.bfdd_privs) {
+		s = vrf_socket(AF_PACKET, SOCK_RAW, ETH_P_IP, vrf->vrf_id,
+			       vrf->name);
+	}
+
+	if (s == -1)
+		zlog_fatal("echo-socket: socket: %s", strerror(errno));
+
+	struct sock_fprog pf;
+	struct sockaddr_ll sll = {0};
+
+	/* adjust filter for socket to only receive ECHO packets */
+	pf.filter = my_filterudp;
+	pf.len = MY_FILTER_LENGTH;
+	if (setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &pf, sizeof(pf)) ==
+	    -1) {
+		zlog_warn("%s: setsockopt(SO_ATTACH_FILTER): %s", __func__,
+			  strerror(errno));
+		close(s);
+		return -1;
+	}
+
+	memset(&sll, 0, sizeof(sll));
+	sll.sll_family = AF_PACKET;
+	sll.sll_protocol = htons(ETH_P_IP);
+	sll.sll_ifindex = 0;
+	if (bind(s, (struct sockaddr *)&sll, sizeof(sll)) < 0) {
+		zlog_warn("Failed to bind echo socket: %s",
+			  safe_strerror(errno));
+		close(s);
+		return -1;
+	}
+
+	return s;
+}
+#else
+int bp_echo_socket(const struct vrf *vrf)
+{
+	int s;
+
+	frr_with_privs(&bglobal.bfdd_privs) {
+		s = vrf_socket(AF_INET, SOCK_DGRAM, 0, vrf->vrf_id, vrf->name);
+	}
+	if (s == -1)
+		zlog_fatal("echo-socket: socket: %s", strerror(errno));
+
+	bp_set_ipopts(s);
+	bp_bind_ip(s, BFD_DEF_ECHO_PORT);
+
+	return s;
+}
+#endif
+
+int bp_echov6_socket(const struct vrf *vrf)
+{
+	int s;
+
+	frr_with_privs(&bglobal.bfdd_privs) {
+		s = vrf_socket(AF_INET6, SOCK_DGRAM, 0, vrf->vrf_id, vrf->name);
+	}
+	if (s == -1) {
+		if (errno != EAFNOSUPPORT)
+			zlog_fatal("echov6-socket: socket: %s",
+				   strerror(errno));
+		else
+			zlog_warn("echov6-socket: V6 is not supported, continuing");
+
+		return -1;
+	}
+
+	bp_set_ipv6opts(s);
+	bp_bind_ipv6(s, BFD_DEF_ECHO_PORT);
+
+	return s;
+}
+
+#ifdef BFD_LINUX
+/* get peer's mac address to be used with Echo packets when they are looped in
+ * peers forwarding plane
+ */
+void bfd_peer_mac_set(int sd, struct bfd_session *bfd,
+		      struct sockaddr_any *peer, struct interface *ifp)
+{
+	struct arpreq arpreq_;
+
+	if (CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_MAC_SET))
+		return;
+	if (ifp->flags & IFF_NOARP)
+		return;
+
+	if (peer->sa_sin.sin_family == AF_INET) {
+		/* IPV4 */
+		struct sockaddr_in *addr =
+			(struct sockaddr_in *)&arpreq_.arp_pa;
+
+		memset(&arpreq_, 0, sizeof(struct arpreq));
+		addr->sin_family = AF_INET;
+		memcpy(&addr->sin_addr.s_addr, &peer->sa_sin.sin_addr,
+		       sizeof(addr->sin_addr));
+		strlcpy(arpreq_.arp_dev, ifp->name, sizeof(arpreq_.arp_dev));
+
+		if (ioctl(sd, SIOCGARP, &arpreq_) < 0) {
+			if (bglobal.debug_network)
+				zlog_debug(
+					"BFD: getting peer's mac on %s failed error %s",
+					ifp->name, strerror(errno));
+			UNSET_FLAG(bfd->flags, BFD_SESS_FLAG_MAC_SET);
+			memset(bfd->peer_hw_addr, 0, sizeof(bfd->peer_hw_addr));
+
+		} else {
+			memcpy(bfd->peer_hw_addr, arpreq_.arp_ha.sa_data,
+			       sizeof(bfd->peer_hw_addr));
+			SET_FLAG(bfd->flags, BFD_SESS_FLAG_MAC_SET);
+		}
+	}
+}
+#endif