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bfd_packet.c
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// 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 [[email protected]]
* Kanna Rajagopal [[email protected]]
* Radhika Mahankali [[email protected]]
*/
#include <zebra.h>
#include <sys/ioctl.h>
#ifdef GNU_LINUX
#include <linux/filter.h>
#endif
#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 (BFD_GETMBIT(cp->flags)) {
cp_debug(is_mhop, &peer, &local, ifindex, vrfid,
"detect non-zero Multipoint (M) flag");
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 = CHECK_FLAG(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));