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bfd.c
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/*********************************************************************
* Copyright 2013 Cumulus Networks, LLC. All rights reserved.
* Copyright 2014,2015,2016,2017 Cumulus Networks, Inc. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; see the file COPYING; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* bfd.c: implements the BFD protocol.
*
* Authors
* -------
* Shrijeet Mukherjee [[email protected]]
* Kanna Rajagopal [[email protected]]
* Radhika Mahankali [[email protected]]
*/
#include <zebra.h>
#include "lib/jhash.h"
#include "bfd.h"
DEFINE_MTYPE_STATIC(BFDD, BFDD_CONFIG, "long-lived configuration memory")
DEFINE_MTYPE_STATIC(BFDD, BFDD_SESSION_OBSERVER, "Session observer")
DEFINE_MTYPE_STATIC(BFDD, BFDD_VRF, "BFD VRF")
/*
* Prototypes
*/
static uint32_t ptm_bfd_gen_ID(void);
static void ptm_bfd_echo_xmt_TO(struct bfd_session *bfd);
static struct bfd_session *bfd_find_disc(struct sockaddr_any *sa,
uint32_t ldisc);
static int bfd_session_update(struct bfd_session *bs, struct bfd_peer_cfg *bpc);
static const char *get_diag_str(int diag);
static void bs_admin_down_handler(struct bfd_session *bs, int nstate);
static void bs_down_handler(struct bfd_session *bs, int nstate);
static void bs_init_handler(struct bfd_session *bs, int nstate);
static void bs_up_handler(struct bfd_session *bs, int nstate);
/* Zeroed array with the size of an IPv6 address. */
struct in6_addr zero_addr;
/*
* Functions
*/
void gen_bfd_key(struct bfd_key *key, struct sockaddr_any *peer,
struct sockaddr_any *local, bool mhop, const char *ifname,
const char *vrfname)
{
memset(key, 0, sizeof(*key));
switch (peer->sa_sin.sin_family) {
case AF_INET:
key->family = AF_INET;
memcpy(&key->peer, &peer->sa_sin.sin_addr,
sizeof(peer->sa_sin.sin_addr));
memcpy(&key->local, &local->sa_sin.sin_addr,
sizeof(local->sa_sin.sin_addr));
break;
case AF_INET6:
key->family = AF_INET6;
memcpy(&key->peer, &peer->sa_sin6.sin6_addr,
sizeof(peer->sa_sin6.sin6_addr));
memcpy(&key->local, &local->sa_sin6.sin6_addr,
sizeof(local->sa_sin6.sin6_addr));
break;
}
key->mhop = mhop;
if (ifname && ifname[0])
strlcpy(key->ifname, ifname, sizeof(key->ifname));
if (vrfname && vrfname[0])
strlcpy(key->vrfname, vrfname, sizeof(key->vrfname));
else
strlcpy(key->vrfname, VRF_DEFAULT_NAME, sizeof(key->vrfname));
}
struct bfd_session *bs_peer_find(struct bfd_peer_cfg *bpc)
{
struct bfd_session *bs;
struct peer_label *pl;
struct bfd_key key;
/* Try to find label first. */
if (bpc->bpc_has_label) {
pl = pl_find(bpc->bpc_label);
if (pl != NULL) {
bs = pl->pl_bs;
return bs;
}
}
/* Otherwise fallback to peer/local hash lookup. */
gen_bfd_key(&key, &bpc->bpc_peer, &bpc->bpc_local, bpc->bpc_mhop,
bpc->bpc_localif, bpc->bpc_vrfname);
return bfd_key_lookup(key);
}
/*
* Starts a disabled BFD session.
*
* A session is disabled when the specified interface/VRF doesn't exist
* yet. It might happen on FRR boot or with virtual interfaces.
*/
int bfd_session_enable(struct bfd_session *bs)
{
struct interface *ifp = NULL;
struct vrf *vrf = NULL;
int psock;
/*
* If the interface or VRF doesn't exist, then we must register
* the session but delay its start.
*/
if (bs->key.vrfname[0]) {
vrf = vrf_lookup_by_name(bs->key.vrfname);
if (vrf == NULL) {
log_error(
"session-enable: specified VRF doesn't exists.");
return 0;
}
}
if (bs->key.ifname[0]) {
if (vrf)
ifp = if_lookup_by_name(bs->key.ifname, vrf->vrf_id);
else
ifp = if_lookup_by_name_all_vrf(bs->key.ifname);
if (ifp == NULL) {
log_error(
"session-enable: specified interface doesn't exists.");
return 0;
}
if (bs->key.ifname[0] && !vrf) {
vrf = vrf_lookup_by_id(ifp->vrf_id);
if (vrf == NULL) {
log_error(
"session-enable: specified VRF doesn't exists.");
return 0;
}
}
}
/* Assign interface/VRF pointers. */
bs->vrf = vrf;
if (bs->vrf == NULL)
bs->vrf = vrf_lookup_by_id(VRF_DEFAULT);
if (bs->key.ifname[0]
&& BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH) == 0)
bs->ifp = ifp;
/* Sanity check: don't leak open sockets. */
if (bs->sock != -1) {
log_debug("session-enable: previous socket open");
close(bs->sock);
bs->sock = -1;
}
/*
* Get socket for transmitting control packets. Note that if we
* could use the destination port (3784) for the source
* port we wouldn't need a socket per session.
*/
if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_IPV6) == 0) {
psock = bp_peer_socket(bs);
if (psock == -1)
return 0;
} else {
psock = bp_peer_socketv6(bs);
if (psock == -1)
return 0;
}
/*
* We've got a valid socket, lets start the timers and the
* protocol.
*/
bs->sock = psock;
bfd_recvtimer_update(bs);
ptm_bfd_start_xmt_timer(bs, false);
return 0;
}
/*
* Disabled a running BFD session.
*
* A session is disabled when the specified interface/VRF gets removed
* (e.g. virtual interfaces).
*/
void bfd_session_disable(struct bfd_session *bs)
{
/* Free up socket resources. */
if (bs->sock != -1) {
close(bs->sock);
bs->sock = -1;
}
/* Disable all timers. */
bfd_recvtimer_delete(bs);
bfd_echo_recvtimer_delete(bs);
bfd_xmttimer_delete(bs);
bfd_echo_xmttimer_delete(bs);
}
static uint32_t ptm_bfd_gen_ID(void)
{
uint32_t session_id;
/*
* RFC 5880, Section 6.8.1. recommends that we should generate
* random session identification numbers.
*/
do {
session_id = ((random() << 16) & 0xFFFF0000)
| (random() & 0x0000FFFF);
} while (session_id == 0 || bfd_id_lookup(session_id) != NULL);
return session_id;
}
void ptm_bfd_start_xmt_timer(struct bfd_session *bfd, bool is_echo)
{
uint64_t jitter, xmt_TO;
int maxpercent;
xmt_TO = is_echo ? bfd->echo_xmt_TO : bfd->xmt_TO;
/*
* From section 6.5.2: trasmit interval should be randomly jittered
* between
* 75% and 100% of nominal value, unless detect_mult is 1, then should
* be
* between 75% and 90%.
*/
maxpercent = (bfd->detect_mult == 1) ? 16 : 26;
jitter = (xmt_TO * (75 + (random() % maxpercent))) / 100;
/* XXX remove that division above */
if (is_echo)
bfd_echo_xmttimer_update(bfd, jitter);
else
bfd_xmttimer_update(bfd, jitter);
}
static void ptm_bfd_echo_xmt_TO(struct bfd_session *bfd)
{
/* Send the scheduled echo packet */
ptm_bfd_echo_snd(bfd);
/* Restart the timer for next time */
ptm_bfd_start_xmt_timer(bfd, true);
}
void ptm_bfd_xmt_TO(struct bfd_session *bfd, int fbit)
{
/* Send the scheduled control packet */
ptm_bfd_snd(bfd, fbit);
/* Restart the timer for next time */
ptm_bfd_start_xmt_timer(bfd, false);
}
void ptm_bfd_echo_stop(struct bfd_session *bfd)
{
bfd->echo_xmt_TO = 0;
bfd->echo_detect_TO = 0;
BFD_UNSET_FLAG(bfd->flags, BFD_SESS_FLAG_ECHO_ACTIVE);
bfd_echo_xmttimer_delete(bfd);
bfd_echo_recvtimer_delete(bfd);
}
void ptm_bfd_echo_start(struct bfd_session *bfd)
{
bfd->echo_detect_TO = (bfd->remote_detect_mult * bfd->echo_xmt_TO);
if (bfd->echo_detect_TO > 0)
ptm_bfd_echo_xmt_TO(bfd);
}
void ptm_bfd_sess_up(struct bfd_session *bfd)
{
int old_state = bfd->ses_state;
bfd->local_diag = 0;
bfd->ses_state = PTM_BFD_UP;
monotime(&bfd->uptime);
/* Connection is up, lets negotiate timers. */
bfd_set_polling(bfd);
/* Start sending control packets with poll bit immediately. */
ptm_bfd_snd(bfd, 0);
control_notify(bfd);
if (old_state != bfd->ses_state) {
bfd->stats.session_up++;
log_info("state-change: [%s] %s -> %s", bs_to_string(bfd),
state_list[old_state].str,
state_list[bfd->ses_state].str);
}
}
void ptm_bfd_sess_dn(struct bfd_session *bfd, uint8_t diag)
{
int old_state = bfd->ses_state;
bfd->local_diag = diag;
bfd->discrs.remote_discr = 0;
bfd->ses_state = PTM_BFD_DOWN;
bfd->polling = 0;
bfd->demand_mode = 0;
monotime(&bfd->downtime);
ptm_bfd_snd(bfd, 0);
/* Slow down the control packets, the connection is down. */
bs_set_slow_timers(bfd);
/* only signal clients when going from up->down state */
if (old_state == PTM_BFD_UP)
control_notify(bfd);
/* Stop echo packet transmission if they are active */
if (BFD_CHECK_FLAG(bfd->flags, BFD_SESS_FLAG_ECHO_ACTIVE))
ptm_bfd_echo_stop(bfd);
if (old_state != bfd->ses_state) {
bfd->stats.session_down++;
log_info("state-change: [%s] %s -> %s reason:%s",
bs_to_string(bfd), state_list[old_state].str,
state_list[bfd->ses_state].str,
get_diag_str(bfd->local_diag));
}
}
static struct bfd_session *bfd_find_disc(struct sockaddr_any *sa,
uint32_t ldisc)
{
struct bfd_session *bs;
bs = bfd_id_lookup(ldisc);
if (bs == NULL)
return NULL;
switch (bs->key.family) {
case AF_INET:
if (memcmp(&sa->sa_sin.sin_addr, &bs->key.peer,
sizeof(sa->sa_sin.sin_addr)))
return NULL;
break;
case AF_INET6:
if (memcmp(&sa->sa_sin6.sin6_addr, &bs->key.peer,
sizeof(sa->sa_sin6.sin6_addr)))
return NULL;
break;
}
return bs;
}
struct bfd_session *ptm_bfd_sess_find(struct bfd_pkt *cp,
struct sockaddr_any *peer,
struct sockaddr_any *local,
ifindex_t ifindex, vrf_id_t vrfid,
bool is_mhop)
{
struct interface *ifp;
struct vrf *vrf;
struct bfd_key key;
/* Find our session using the ID signaled by the remote end. */
if (cp->discrs.remote_discr)
return bfd_find_disc(peer, ntohl(cp->discrs.remote_discr));
/* Search for session without using discriminator. */
ifp = if_lookup_by_index(ifindex, vrfid);
if (vrfid != VRF_DEFAULT)
vrf = vrf_lookup_by_id(vrfid);
else
vrf = NULL;
gen_bfd_key(&key, peer, local, is_mhop, ifp ? ifp->name : NULL,
vrf ? vrf->name : VRF_DEFAULT_NAME);
/* XXX maybe remoteDiscr should be checked for remoteHeard cases. */
return bfd_key_lookup(key);
}
int bfd_xmt_cb(struct thread *t)
{
struct bfd_session *bs = THREAD_ARG(t);
ptm_bfd_xmt_TO(bs, 0);
return 0;
}
int bfd_echo_xmt_cb(struct thread *t)
{
struct bfd_session *bs = THREAD_ARG(t);
if (bs->echo_xmt_TO > 0)
ptm_bfd_echo_xmt_TO(bs);
return 0;
}
/* Was ptm_bfd_detect_TO() */
int bfd_recvtimer_cb(struct thread *t)
{
struct bfd_session *bs = THREAD_ARG(t);
switch (bs->ses_state) {
case PTM_BFD_INIT:
case PTM_BFD_UP:
ptm_bfd_sess_dn(bs, BD_CONTROL_EXPIRED);
bfd_recvtimer_update(bs);
break;
default:
/* Second detect time expiration, zero remote discr (section
* 6.5.1)
*/
bs->discrs.remote_discr = 0;
break;
}
return 0;
}
/* Was ptm_bfd_echo_detect_TO() */
int bfd_echo_recvtimer_cb(struct thread *t)
{
struct bfd_session *bs = THREAD_ARG(t);
switch (bs->ses_state) {
case PTM_BFD_INIT:
case PTM_BFD_UP:
ptm_bfd_sess_dn(bs, BD_ECHO_FAILED);
break;
}
return 0;
}
struct bfd_session *bfd_session_new(void)
{
struct bfd_session *bs;
bs = XCALLOC(MTYPE_BFDD_CONFIG, sizeof(*bs));
bs->timers.desired_min_tx = BFD_DEFDESIREDMINTX;
bs->timers.required_min_rx = BFD_DEFREQUIREDMINRX;
bs->timers.required_min_echo = BFD_DEF_REQ_MIN_ECHO;
bs->detect_mult = BFD_DEFDETECTMULT;
bs->mh_ttl = BFD_DEF_MHOP_TTL;
bs->ses_state = PTM_BFD_DOWN;
/* Initiate connection with slow timers. */
bs_set_slow_timers(bs);
/* Initiate remote settings as well. */
bs->remote_timers = bs->cur_timers;
bs->remote_detect_mult = BFD_DEFDETECTMULT;
bs->sock = -1;
monotime(&bs->uptime);
bs->downtime = bs->uptime;
return bs;
}
int bfd_session_update_label(struct bfd_session *bs, const char *nlabel)
{
/* New label treatment:
* - Check if the label is taken;
* - Try to allocate the memory for it and register;
*/
if (bs->pl == NULL) {
if (pl_find(nlabel) != NULL) {
/* Someone is already using it. */
return -1;
}
if (pl_new(nlabel, bs) == NULL)
return -1;
return 0;
}
/*
* Test label change consistency:
* - Do nothing if it's the same label;
* - Check if the future label is already taken;
* - Change label;
*/
if (strcmp(nlabel, bs->pl->pl_label) == 0)
return -1;
if (pl_find(nlabel) != NULL)
return -1;
strlcpy(bs->pl->pl_label, nlabel, sizeof(bs->pl->pl_label));
return 0;
}
static void _bfd_session_update(struct bfd_session *bs,
struct bfd_peer_cfg *bpc)
{
if (bpc->bpc_echo) {
/* Check if echo mode is already active. */
if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_ECHO))
goto skip_echo;
BFD_SET_FLAG(bs->flags, BFD_SESS_FLAG_ECHO);
/* Activate/update echo receive timeout timer. */
bs_echo_timer_handler(bs);
} else {
/* Check if echo mode is already disabled. */
if (!BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_ECHO))
goto skip_echo;
BFD_UNSET_FLAG(bs->flags, BFD_SESS_FLAG_ECHO);
ptm_bfd_echo_stop(bs);
}
skip_echo:
if (bpc->bpc_has_txinterval)
bs->timers.desired_min_tx = bpc->bpc_txinterval * 1000;
if (bpc->bpc_has_recvinterval)
bs->timers.required_min_rx = bpc->bpc_recvinterval * 1000;
if (bpc->bpc_has_detectmultiplier)
bs->detect_mult = bpc->bpc_detectmultiplier;
if (bpc->bpc_has_echointerval)
bs->timers.required_min_echo = bpc->bpc_echointerval * 1000;
if (bpc->bpc_has_label)
bfd_session_update_label(bs, bpc->bpc_label);
if (bpc->bpc_shutdown) {
/* Check if already shutdown. */
if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_SHUTDOWN))
return;
BFD_SET_FLAG(bs->flags, BFD_SESS_FLAG_SHUTDOWN);
/* Disable all events. */
bfd_recvtimer_delete(bs);
bfd_echo_recvtimer_delete(bs);
bfd_xmttimer_delete(bs);
bfd_echo_xmttimer_delete(bs);
/* Change and notify state change. */
bs->ses_state = PTM_BFD_ADM_DOWN;
control_notify(bs);
/* Don't try to send packets with a disabled session. */
if (bs->sock != -1)
ptm_bfd_snd(bs, 0);
} else {
/* Check if already working. */
if (!BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_SHUTDOWN))
return;
BFD_UNSET_FLAG(bs->flags, BFD_SESS_FLAG_SHUTDOWN);
/* Change and notify state change. */
bs->ses_state = PTM_BFD_DOWN;
control_notify(bs);
/* Enable all timers. */
bfd_recvtimer_update(bs);
bfd_xmttimer_update(bs, bs->xmt_TO);
}
if (bpc->bpc_cbit) {
if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_CBIT))
return;
BFD_SET_FLAG(bs->flags, BFD_SESS_FLAG_CBIT);
} else {
if (!BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_CBIT))
return;
BFD_UNSET_FLAG(bs->flags, BFD_SESS_FLAG_CBIT);
}
}
static int bfd_session_update(struct bfd_session *bs, struct bfd_peer_cfg *bpc)
{
/* User didn't want to update, return failure. */
if (bpc->bpc_createonly)
return -1;
_bfd_session_update(bs, bpc);
control_notify_config(BCM_NOTIFY_CONFIG_UPDATE, bs);
return 0;
}
void bfd_session_free(struct bfd_session *bs)
{
struct bfd_session_observer *bso;
bfd_session_disable(bs);
bfd_key_delete(bs->key);
bfd_id_delete(bs->discrs.my_discr);
/* Remove observer if any. */
TAILQ_FOREACH(bso, &bglobal.bg_obslist, bso_entry) {
if (bso->bso_bs != bs)
continue;
break;
}
if (bso != NULL)
bs_observer_del(bso);
pl_free(bs->pl);
XFREE(MTYPE_BFDD_CONFIG, bs);
}
struct bfd_session *ptm_bfd_sess_new(struct bfd_peer_cfg *bpc)
{
struct bfd_session *bfd, *l_bfd;
/* check to see if this needs a new session */
l_bfd = bs_peer_find(bpc);
if (l_bfd) {
/* Requesting a duplicated peer means update configuration. */
if (bfd_session_update(l_bfd, bpc) == 0)
return l_bfd;
else
return NULL;
}
/* Get BFD session storage with its defaults. */
bfd = bfd_session_new();
if (bfd == NULL) {
log_error("session-new: allocation failed");
return NULL;
}
/*
* Store interface/VRF name in case we need to delay session
* start. See `bfd_session_enable` for more information.
*/
if (bpc->bpc_has_localif)
strlcpy(bfd->key.ifname, bpc->bpc_localif,
sizeof(bfd->key.ifname));
if (bpc->bpc_has_vrfname)
strlcpy(bfd->key.vrfname, bpc->bpc_vrfname,
sizeof(bfd->key.vrfname));
else
strlcpy(bfd->key.vrfname, VRF_DEFAULT_NAME,
sizeof(bfd->key.vrfname));
/* Copy remaining data. */
if (bpc->bpc_ipv4 == false)
BFD_SET_FLAG(bfd->flags, BFD_SESS_FLAG_IPV6);
bfd->key.family = (bpc->bpc_ipv4) ? AF_INET : AF_INET6;
switch (bfd->key.family) {
case AF_INET:
memcpy(&bfd->key.peer, &bpc->bpc_peer.sa_sin.sin_addr,
sizeof(bpc->bpc_peer.sa_sin.sin_addr));
memcpy(&bfd->key.local, &bpc->bpc_local.sa_sin.sin_addr,
sizeof(bpc->bpc_local.sa_sin.sin_addr));
break;
case AF_INET6:
memcpy(&bfd->key.peer, &bpc->bpc_peer.sa_sin6.sin6_addr,
sizeof(bpc->bpc_peer.sa_sin6.sin6_addr));
memcpy(&bfd->key.local, &bpc->bpc_local.sa_sin6.sin6_addr,
sizeof(bpc->bpc_local.sa_sin6.sin6_addr));
break;
default:
assert(1);
break;
}
if (bpc->bpc_mhop)
BFD_SET_FLAG(bfd->flags, BFD_SESS_FLAG_MH);
bfd->key.mhop = bpc->bpc_mhop;
if (bs_registrate(bfd) == NULL)
return NULL;
/* Apply other configurations. */
_bfd_session_update(bfd, bpc);
return bfd;
}
struct bfd_session *bs_registrate(struct bfd_session *bfd)
{
/* Registrate session into data structures. */
bfd_key_insert(bfd);
bfd->discrs.my_discr = ptm_bfd_gen_ID();
bfd_id_insert(bfd);
/* Try to enable session and schedule for packet receive/send. */
if (bfd_session_enable(bfd) == -1) {
/* Unrecoverable failure, remove the session/peer. */
bfd_session_free(bfd);
return NULL;
}
/* Add observer if we have moving parts. */
if (bfd->key.ifname[0] || bfd->key.vrfname[0] || bfd->sock == -1)
bs_observer_add(bfd);
log_info("session-new: %s", bs_to_string(bfd));
control_notify_config(BCM_NOTIFY_CONFIG_ADD, bfd);
return bfd;
}
int ptm_bfd_sess_del(struct bfd_peer_cfg *bpc)
{
struct bfd_session *bs;
/* Find session and call free(). */
bs = bs_peer_find(bpc);
if (bs == NULL)
return -1;
/* This pointer is being referenced, don't let it be deleted. */
if (bs->refcount > 0) {
log_error("session-delete: refcount failure: %" PRIu64
" references",
bs->refcount);
return -1;
}
log_info("session-delete: %s", bs_to_string(bs));
control_notify_config(BCM_NOTIFY_CONFIG_DELETE, bs);
bfd_session_free(bs);
return 0;
}
void bfd_set_polling(struct bfd_session *bs)
{
/*
* Start polling procedure: the only timers that require polling
* to change value without losing connection are:
*
* - Desired minimum transmission interval;
* - Required minimum receive interval;
*
* RFC 5880, Section 6.8.3.
*/
bs->polling = 1;
}
/*
* bs_<state>_handler() functions implement the BFD state machine
* transition mechanism. `<state>` is the current session state and
* the parameter `nstate` is the peer new state.
*/
static void bs_admin_down_handler(struct bfd_session *bs
__attribute__((__unused__)),
int nstate __attribute__((__unused__)))
{
/*
* We are administratively down, there is no state machine
* handling.
*/
}
static void bs_down_handler(struct bfd_session *bs, int nstate)
{
switch (nstate) {
case PTM_BFD_ADM_DOWN:
/*
* Remote peer doesn't want to talk, so lets keep the
* connection down.
*/
case PTM_BFD_UP:
/* Peer can't be up yet, wait it go to 'init' or 'down'. */
break;
case PTM_BFD_DOWN:
/*
* Remote peer agreed that the path is down, lets try to
* bring it up.
*/
bs->ses_state = PTM_BFD_INIT;
break;
case PTM_BFD_INIT:
/*
* Remote peer told us his path is up, lets turn
* activate the session.
*/
ptm_bfd_sess_up(bs);
break;
default:
log_debug("state-change: unhandled neighbor state: %d", nstate);
break;
}
}
static void bs_init_handler(struct bfd_session *bs, int nstate)
{
switch (nstate) {
case PTM_BFD_ADM_DOWN:
/*
* Remote peer doesn't want to talk, so lets make the
* connection down.
*/
bs->ses_state = PTM_BFD_DOWN;
break;
case PTM_BFD_DOWN:
/* Remote peer hasn't moved to first stage yet. */
break;
case PTM_BFD_INIT:
case PTM_BFD_UP:
/* We agreed on the settings and the path is up. */
ptm_bfd_sess_up(bs);
break;
default:
log_debug("state-change: unhandled neighbor state: %d", nstate);
break;
}
}
static void bs_up_handler(struct bfd_session *bs, int nstate)
{
switch (nstate) {
case PTM_BFD_ADM_DOWN:
case PTM_BFD_DOWN:
/* Peer lost or asked to shutdown connection. */
ptm_bfd_sess_dn(bs, BD_NEIGHBOR_DOWN);
break;
case PTM_BFD_INIT:
case PTM_BFD_UP:
/* Path is up and working. */
break;
default:
log_debug("state-change: unhandled neighbor state: %d", nstate);
break;
}
}
void bs_state_handler(struct bfd_session *bs, int nstate)
{
switch (bs->ses_state) {
case PTM_BFD_ADM_DOWN:
bs_admin_down_handler(bs, nstate);
break;
case PTM_BFD_DOWN:
bs_down_handler(bs, nstate);
break;
case PTM_BFD_INIT:
bs_init_handler(bs, nstate);
break;
case PTM_BFD_UP:
bs_up_handler(bs, nstate);
break;
default:
log_debug("state-change: [%s] is in invalid state: %d",
bs_to_string(bs), nstate);
break;
}
}
/*
* Handles echo timer manipulation after updating timer.
*/
void bs_echo_timer_handler(struct bfd_session *bs)
{
uint32_t old_timer;
/*
* Before doing any echo handling, check if it is possible to
* use it.
*
* - Check for `echo-mode` configuration.
* - Check that we are not using multi hop (RFC 5883,
* Section 3).
* - Check that we are already at the up state.
*/
if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_ECHO) == 0
|| BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_MH)
|| bs->ses_state != PTM_BFD_UP)
return;
/* Remote peer asked to stop echo. */
if (bs->remote_timers.required_min_echo == 0) {
if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_ECHO_ACTIVE))
ptm_bfd_echo_stop(bs);
return;
}
/*
* Calculate the echo transmission timer: we must not send
* echo packets faster than the minimum required time
* announced by the remote system.
*
* RFC 5880, Section 6.8.9.
*/
old_timer = bs->echo_xmt_TO;
if (bs->remote_timers.required_min_echo > bs->timers.required_min_echo)
bs->echo_xmt_TO = bs->remote_timers.required_min_echo;
else
bs->echo_xmt_TO = bs->timers.required_min_echo;
if (BFD_CHECK_FLAG(bs->flags, BFD_SESS_FLAG_ECHO_ACTIVE) == 0
|| old_timer != bs->echo_xmt_TO)
ptm_bfd_echo_start(bs);
}
/*
* RFC 5880 Section 6.5.
*
* When a BFD control packet with the final bit is received, we must
* update the session parameters.
*/
void bs_final_handler(struct bfd_session *bs)
{
/* Start using our new timers. */
bs->cur_timers.desired_min_tx = bs->timers.desired_min_tx;
bs->cur_timers.required_min_rx = bs->timers.required_min_rx;
/*
* TODO: demand mode. See RFC 5880 Section 6.1.
*
* When using demand mode we must disable the detection timer
* for lost control packets.
*/
if (bs->demand_mode) {
/* Notify watchers about changed timers. */
control_notify_config(BCM_NOTIFY_CONFIG_UPDATE, bs);
return;
}
/*
* Calculate detection time based on new timers.
*
* Transmission calculation:
* We must respect the RequiredMinRxInterval from the remote
* system: if our desired transmission timer is more than the
* minimum receive rate, then we must lower it to at least the
* minimum receive interval.
*
* RFC 5880, Section 6.8.3.
*/
if (bs->timers.desired_min_tx > bs->remote_timers.required_min_rx)
bs->xmt_TO = bs->remote_timers.required_min_rx;
else
bs->xmt_TO = bs->timers.desired_min_tx;
/* Apply new transmission timer immediately. */
ptm_bfd_start_xmt_timer(bs, false);
/*
* 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.