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bfd.c
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/* Copyright (c) 2013, 2014 Nicira, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License. */
#include <config.h>
#include "bfd.h"
#include <sys/types.h>
#include <arpa/inet.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <sys/socket.h>
#include "byte-order.h"
#include "connectivity.h"
#include "csum.h"
#include "dpif.h"
#include "dynamic-string.h"
#include "flow.h"
#include "hash.h"
#include "hmap.h"
#include "list.h"
#include "netdev.h"
#include "odp-util.h"
#include "ofpbuf.h"
#include "ovs-thread.h"
#include "openvswitch/types.h"
#include "packets.h"
#include "poll-loop.h"
#include "random.h"
#include "seq.h"
#include "smap.h"
#include "timeval.h"
#include "unaligned.h"
#include "unixctl.h"
#include "util.h"
#include "vlog.h"
VLOG_DEFINE_THIS_MODULE(bfd);
/* XXX Finish BFD.
*
* The goal of this module is to replace CFM with something both more flexible
* and standards compliant. In service of this goal, the following needs to be
* done.
*
* - Compliance
* * Implement Demand mode.
* * Go through the RFC line by line and verify we comply.
* * Test against a hardware implementation. Preferably a popular one.
* * Delete BFD packets with nw_ttl != 255 in the datapath to prevent DOS
* attacks.
*
* - Unit tests.
*
* - Set TOS/PCP on the outer tunnel header when encapped.
*
* - Sending BFD messages should be in its own thread/process.
*
* - Scale testing. How does it operate when there are large number of bfd
* sessions? Do we ever have random flaps? What's the CPU utilization?
*
* - Rely on data traffic for liveness by using BFD demand mode.
* If we're receiving traffic on a port, we can safely assume it's up (modulo
* unidrectional failures). BFD has a demand mode in which it can stay quiet
* unless it feels the need to check the status of the port. Using this, we
* can implement a strategy in which BFD only sends control messages on dark
* interfaces.
*
* - Depending on how one interprets the spec, it appears that a BFD session
* can never change bfd.LocalDiag to "No Diagnostic". We should verify that
* this is what hardware implementations actually do. Seems like "No
* Diagnostic" should be set once a BFD session state goes UP. */
#define BFD_VERSION 1
enum flags {
FLAG_MULTIPOINT = 1 << 0,
FLAG_DEMAND = 1 << 1,
FLAG_AUTH = 1 << 2,
FLAG_CTL = 1 << 3,
FLAG_FINAL = 1 << 4,
FLAG_POLL = 1 << 5
};
enum state {
STATE_ADMIN_DOWN = 0 << 6,
STATE_DOWN = 1 << 6,
STATE_INIT = 2 << 6,
STATE_UP = 3 << 6
};
enum diag {
DIAG_NONE = 0, /* No Diagnostic. */
DIAG_EXPIRED = 1, /* Control Detection Time Expired. */
DIAG_ECHO_FAILED = 2, /* Echo Function Failed. */
DIAG_RMT_DOWN = 3, /* Neighbor Signaled Session Down. */
DIAG_FWD_RESET = 4, /* Forwarding Plane Reset. */
DIAG_PATH_DOWN = 5, /* Path Down. */
DIAG_CPATH_DOWN = 6, /* Concatenated Path Down. */
DIAG_ADMIN_DOWN = 7, /* Administratively Down. */
DIAG_RCPATH_DOWN = 8 /* Reverse Concatenated Path Down. */
};
/* RFC 5880 Section 4.1
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |Vers | Diag |Sta|P|F|C|A|D|M| Detect Mult | Length |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | My Discriminator |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Your Discriminator |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Desired Min TX Interval |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Required Min RX Interval |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Required Min Echo RX Interval |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ */
struct msg {
uint8_t vers_diag; /* Version and diagnostic. */
uint8_t flags; /* 2bit State field followed by flags. */
uint8_t mult; /* Fault detection multiplier. */
uint8_t length; /* Length of this BFD message. */
ovs_be32 my_disc; /* My discriminator. */
ovs_be32 your_disc; /* Your discriminator. */
ovs_be32 min_tx; /* Desired minimum tx interval. */
ovs_be32 min_rx; /* Required minimum rx interval. */
ovs_be32 min_rx_echo; /* Required minimum echo rx interval. */
};
BUILD_ASSERT_DECL(BFD_PACKET_LEN == sizeof(struct msg));
#define DIAG_MASK 0x1f
#define VERS_SHIFT 5
#define STATE_MASK 0xC0
#define FLAGS_MASK 0x3f
struct bfd {
struct hmap_node node; /* In 'all_bfds'. */
uint32_t disc; /* bfd.LocalDiscr. Key in 'all_bfds' hmap. */
char *name; /* Name used for logging. */
bool cpath_down; /* Concatenated Path Down. */
uint8_t mult; /* bfd.DetectMult. */
struct netdev *netdev;
uint64_t rx_packets; /* Packets received by 'netdev'. */
enum state state; /* bfd.SessionState. */
enum state rmt_state; /* bfd.RemoteSessionState. */
enum diag diag; /* bfd.LocalDiag. */
enum diag rmt_diag; /* Remote diagnostic. */
enum flags flags; /* Flags sent on messages. */
enum flags rmt_flags; /* Flags last received. */
uint32_t rmt_disc; /* bfd.RemoteDiscr. */
uint8_t local_eth_src[ETH_ADDR_LEN]; /* Local eth src address. */
uint8_t local_eth_dst[ETH_ADDR_LEN]; /* Local eth dst address. */
uint8_t rmt_eth_dst[ETH_ADDR_LEN]; /* Remote eth dst address. */
ovs_be32 ip_src; /* IPv4 source address. */
ovs_be32 ip_dst; /* IPv4 destination address. */
uint16_t udp_src; /* UDP source port. */
/* All timers in milliseconds. */
long long int rmt_min_rx; /* bfd.RemoteMinRxInterval. */
long long int rmt_min_tx; /* Remote minimum TX interval. */
long long int cfg_min_tx; /* Configured minimum TX rate. */
long long int cfg_min_rx; /* Configured required minimum RX rate. */
long long int poll_min_tx; /* Min TX negotating in a poll sequence. */
long long int poll_min_rx; /* Min RX negotating in a poll sequence. */
long long int min_tx; /* bfd.DesiredMinTxInterval. */
long long int min_rx; /* bfd.RequiredMinRxInterval. */
long long int last_tx; /* Last TX time. */
long long int next_tx; /* Next TX time. */
long long int detect_time; /* RFC 5880 6.8.4 Detection time. */
bool last_forwarding; /* Last calculation of forwarding flag. */
int forwarding_override; /* Manual override of 'forwarding' status. */
atomic_bool check_tnl_key; /* Verify tunnel key of inbound packets? */
struct ovs_refcount ref_cnt;
/* When forward_if_rx is true, bfd_forwarding() will return
* true as long as there are incoming packets received.
* Note, forwarding_override still has higher priority. */
bool forwarding_if_rx;
long long int forwarding_if_rx_detect_time;
/* When 'bfd->forwarding_if_rx' is set, at least one bfd control packet
* is required to be received every 100 * bfd->cfg_min_rx. If bfd
* control packet is not received within this interval, even if data
* packets are received, the bfd->forwarding will still be false. */
long long int demand_rx_bfd_time;
/* BFD decay related variables. */
bool in_decay; /* True when bfd is in decay. */
int decay_min_rx; /* min_rx is set to decay_min_rx when */
/* in decay. */
int decay_rx_ctl; /* Count bfd packets received within decay */
/* detect interval. */
uint64_t decay_rx_packets; /* Packets received by 'netdev'. */
long long int decay_detect_time; /* Decay detection time. */
uint64_t flap_count; /* Counts bfd forwarding flaps. */
/* True when the variables returned by bfd_get_status() are changed
* since last check. */
bool status_changed;
};
static struct ovs_mutex mutex = OVS_MUTEX_INITIALIZER;
static struct hmap all_bfds__ = HMAP_INITIALIZER(&all_bfds__);
static struct hmap *const all_bfds OVS_GUARDED_BY(mutex) = &all_bfds__;
static bool bfd_lookup_ip(const char *host_name, struct in_addr *)
OVS_REQUIRES(mutex);
static bool bfd_forwarding__(struct bfd *) OVS_REQUIRES(mutex);
static bool bfd_in_poll(const struct bfd *) OVS_REQUIRES(mutex);
static void bfd_poll(struct bfd *bfd) OVS_REQUIRES(mutex);
static const char *bfd_diag_str(enum diag) OVS_REQUIRES(mutex);
static const char *bfd_state_str(enum state) OVS_REQUIRES(mutex);
static long long int bfd_min_tx(const struct bfd *) OVS_REQUIRES(mutex);
static long long int bfd_tx_interval(const struct bfd *)
OVS_REQUIRES(mutex);
static long long int bfd_rx_interval(const struct bfd *)
OVS_REQUIRES(mutex);
static void bfd_set_next_tx(struct bfd *) OVS_REQUIRES(mutex);
static void bfd_set_state(struct bfd *, enum state, enum diag)
OVS_REQUIRES(mutex);
static uint32_t generate_discriminator(void) OVS_REQUIRES(mutex);
static void bfd_put_details(struct ds *, const struct bfd *)
OVS_REQUIRES(mutex);
static uint64_t bfd_rx_packets(const struct bfd *) OVS_REQUIRES(mutex);
static void bfd_try_decay(struct bfd *) OVS_REQUIRES(mutex);
static void bfd_decay_update(struct bfd *) OVS_REQUIRES(mutex);
static void bfd_status_changed(struct bfd *) OVS_REQUIRES(mutex);
static void bfd_forwarding_if_rx_update(struct bfd *) OVS_REQUIRES(mutex);
static void bfd_unixctl_show(struct unixctl_conn *, int argc,
const char *argv[], void *aux OVS_UNUSED);
static void bfd_unixctl_set_forwarding_override(struct unixctl_conn *,
int argc, const char *argv[],
void *aux OVS_UNUSED);
static void log_msg(enum vlog_level, const struct msg *, const char *message,
const struct bfd *) OVS_REQUIRES(mutex);
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(20, 20);
/* Returns true if the interface on which 'bfd' is running may be used to
* forward traffic according to the BFD session state. */
bool
bfd_forwarding(struct bfd *bfd) OVS_EXCLUDED(mutex)
{
bool ret;
ovs_mutex_lock(&mutex);
ret = bfd_forwarding__(bfd);
ovs_mutex_unlock(&mutex);
return ret;
}
/* When forwarding_if_rx is enabled, if there are packets received,
* updates forwarding_if_rx_detect_time. */
void
bfd_account_rx(struct bfd *bfd, const struct dpif_flow_stats *stats)
{
if (stats->n_packets && bfd->forwarding_if_rx) {
ovs_mutex_lock(&mutex);
bfd_forwarding__(bfd);
bfd_forwarding_if_rx_update(bfd);
bfd_forwarding__(bfd);
ovs_mutex_unlock(&mutex);
}
}
/* Returns and resets the 'bfd->status_changed'. */
bool
bfd_check_status_change(struct bfd *bfd) OVS_EXCLUDED(mutex)
{
bool ret;
ovs_mutex_lock(&mutex);
ret = bfd->status_changed;
bfd->status_changed = false;
ovs_mutex_unlock(&mutex);
return ret;
}
/* Returns a 'smap' of key value pairs representing the status of 'bfd'
* intended for the OVS database. */
void
bfd_get_status(const struct bfd *bfd, struct smap *smap)
OVS_EXCLUDED(mutex)
{
ovs_mutex_lock(&mutex);
smap_add(smap, "forwarding",
bfd_forwarding__(CONST_CAST(struct bfd *, bfd))
? "true" : "false");
smap_add(smap, "state", bfd_state_str(bfd->state));
smap_add(smap, "diagnostic", bfd_diag_str(bfd->diag));
smap_add_format(smap, "flap_count", "%"PRIu64, bfd->flap_count);
if (bfd->state != STATE_DOWN) {
smap_add(smap, "remote_state", bfd_state_str(bfd->rmt_state));
smap_add(smap, "remote_diagnostic", bfd_diag_str(bfd->rmt_diag));
}
ovs_mutex_unlock(&mutex);
}
/* Initializes, destroys, or reconfigures the BFD session 'bfd' (named 'name'),
* according to the database configuration contained in 'cfg'. Takes ownership
* of 'bfd', which may be NULL. Returns a BFD object which may be used as a
* handle for the session, or NULL if BFD is not enabled according to 'cfg'.
* Also returns NULL if cfg is NULL. */
struct bfd *
bfd_configure(struct bfd *bfd, const char *name, const struct smap *cfg,
struct netdev *netdev) OVS_EXCLUDED(mutex)
{
static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
static atomic_uint16_t udp_src = ATOMIC_VAR_INIT(0);
int decay_min_rx;
long long int min_tx, min_rx;
bool need_poll = false;
bool cfg_min_rx_changed = false;
bool cpath_down, forwarding_if_rx;
const char *hwaddr, *ip_src, *ip_dst;
struct in_addr in_addr;
uint8_t ea[ETH_ADDR_LEN];
if (ovsthread_once_start(&once)) {
unixctl_command_register("bfd/show", "[interface]", 0, 1,
bfd_unixctl_show, NULL);
unixctl_command_register("bfd/set-forwarding",
"[interface] normal|false|true", 1, 2,
bfd_unixctl_set_forwarding_override, NULL);
ovsthread_once_done(&once);
}
if (!cfg || !smap_get_bool(cfg, "enable", false)) {
bfd_unref(bfd);
return NULL;
}
ovs_mutex_lock(&mutex);
if (!bfd) {
bfd = xzalloc(sizeof *bfd);
bfd->name = xstrdup(name);
bfd->forwarding_override = -1;
bfd->disc = generate_discriminator();
hmap_insert(all_bfds, &bfd->node, bfd->disc);
bfd->diag = DIAG_NONE;
bfd->min_tx = 1000;
bfd->mult = 3;
ovs_refcount_init(&bfd->ref_cnt);
bfd->netdev = netdev_ref(netdev);
bfd->rx_packets = bfd_rx_packets(bfd);
bfd->in_decay = false;
bfd->flap_count = 0;
/* RFC 5881 section 4
* The source port MUST be in the range 49152 through 65535. The same
* UDP source port number MUST be used for all BFD Control packets
* associated with a particular session. The source port number SHOULD
* be unique among all BFD sessions on the system. */
atomic_add(&udp_src, 1, &bfd->udp_src);
bfd->udp_src = (bfd->udp_src % 16384) + 49152;
bfd_set_state(bfd, STATE_DOWN, DIAG_NONE);
bfd_status_changed(bfd);
}
atomic_store(&bfd->check_tnl_key,
smap_get_bool(cfg, "check_tnl_key", false));
min_tx = smap_get_int(cfg, "min_tx", 100);
min_tx = MAX(min_tx, 100);
if (bfd->cfg_min_tx != min_tx) {
bfd->cfg_min_tx = min_tx;
if (bfd->state != STATE_UP
|| (!bfd_in_poll(bfd) && bfd->cfg_min_tx < bfd->min_tx)) {
bfd->min_tx = bfd->cfg_min_tx;
}
need_poll = true;
}
min_rx = smap_get_int(cfg, "min_rx", 1000);
min_rx = MAX(min_rx, 100);
if (bfd->cfg_min_rx != min_rx) {
bfd->cfg_min_rx = min_rx;
if (bfd->state != STATE_UP
|| (!bfd_in_poll(bfd) && bfd->cfg_min_rx > bfd->min_rx)) {
bfd->min_rx = bfd->cfg_min_rx;
}
cfg_min_rx_changed = true;
need_poll = true;
}
decay_min_rx = smap_get_int(cfg, "decay_min_rx", 0);
if (bfd->decay_min_rx != decay_min_rx || cfg_min_rx_changed) {
if (decay_min_rx > 0 && decay_min_rx < bfd->cfg_min_rx) {
VLOG_WARN("%s: decay_min_rx cannot be less than %lld ms",
bfd->name, bfd->cfg_min_rx);
bfd->decay_min_rx = 0;
} else {
bfd->decay_min_rx = decay_min_rx;
}
/* Resets decay. */
bfd->in_decay = false;
bfd_decay_update(bfd);
need_poll = true;
}
cpath_down = smap_get_bool(cfg, "cpath_down", false);
if (bfd->cpath_down != cpath_down) {
bfd->cpath_down = cpath_down;
bfd_set_state(bfd, bfd->state, DIAG_NONE);
need_poll = true;
}
hwaddr = smap_get(cfg, "bfd_local_src_mac");
if (hwaddr && eth_addr_from_string(hwaddr, ea)) {
memcpy(bfd->local_eth_src, ea, ETH_ADDR_LEN);
} else {
memset(bfd->local_eth_src, 0, ETH_ADDR_LEN);
}
hwaddr = smap_get(cfg, "bfd_local_dst_mac");
if (hwaddr && eth_addr_from_string(hwaddr, ea)) {
memcpy(bfd->local_eth_dst, ea, ETH_ADDR_LEN);
} else {
memset(bfd->local_eth_dst, 0, ETH_ADDR_LEN);
}
hwaddr = smap_get(cfg, "bfd_remote_dst_mac");
if (hwaddr && eth_addr_from_string(hwaddr, ea)) {
memcpy(bfd->rmt_eth_dst, ea, ETH_ADDR_LEN);
} else {
memset(bfd->rmt_eth_dst, 0, ETH_ADDR_LEN);
}
ip_src = smap_get(cfg, "bfd_src_ip");
if (ip_src && bfd_lookup_ip(ip_src, &in_addr)) {
memcpy(&bfd->ip_src, &in_addr, sizeof in_addr);
} else {
bfd->ip_src = htonl(0xA9FE0101); /* 169.254.1.1. */
}
ip_dst = smap_get(cfg, "bfd_dst_ip");
if (ip_dst && bfd_lookup_ip(ip_dst, &in_addr)) {
memcpy(&bfd->ip_dst, &in_addr, sizeof in_addr);
} else {
bfd->ip_dst = htonl(0xA9FE0100); /* 169.254.1.0. */
}
forwarding_if_rx = smap_get_bool(cfg, "forwarding_if_rx", false);
if (bfd->forwarding_if_rx != forwarding_if_rx) {
bfd->forwarding_if_rx = forwarding_if_rx;
if (bfd->state == STATE_UP && bfd->forwarding_if_rx) {
bfd_forwarding_if_rx_update(bfd);
} else {
bfd->forwarding_if_rx_detect_time = 0;
}
}
if (need_poll) {
bfd_poll(bfd);
}
ovs_mutex_unlock(&mutex);
return bfd;
}
struct bfd *
bfd_ref(const struct bfd *bfd_)
{
struct bfd *bfd = CONST_CAST(struct bfd *, bfd_);
if (bfd) {
ovs_refcount_ref(&bfd->ref_cnt);
}
return bfd;
}
void
bfd_unref(struct bfd *bfd) OVS_EXCLUDED(mutex)
{
if (bfd && ovs_refcount_unref_relaxed(&bfd->ref_cnt) == 1) {
ovs_mutex_lock(&mutex);
bfd_status_changed(bfd);
hmap_remove(all_bfds, &bfd->node);
netdev_close(bfd->netdev);
free(bfd->name);
free(bfd);
ovs_mutex_unlock(&mutex);
}
}
void
bfd_wait(const struct bfd *bfd) OVS_EXCLUDED(mutex)
{
poll_timer_wait_until(bfd_wake_time(bfd));
}
/* Returns the next wake up time. */
long long int
bfd_wake_time(const struct bfd *bfd) OVS_EXCLUDED(mutex)
{
long long int retval;
if (!bfd) {
return LLONG_MAX;
}
ovs_mutex_lock(&mutex);
if (bfd->flags & FLAG_FINAL) {
retval = 0;
} else {
retval = bfd->next_tx;
if (bfd->state > STATE_DOWN) {
retval = MIN(bfd->detect_time, retval);
}
}
ovs_mutex_unlock(&mutex);
return retval;
}
void
bfd_run(struct bfd *bfd) OVS_EXCLUDED(mutex)
{
long long int now;
bool old_in_decay;
ovs_mutex_lock(&mutex);
now = time_msec();
old_in_decay = bfd->in_decay;
if (bfd->state > STATE_DOWN && now >= bfd->detect_time) {
bfd_set_state(bfd, STATE_DOWN, DIAG_EXPIRED);
}
bfd_forwarding__(bfd);
/* Decay may only happen when state is STATE_UP, bfd->decay_min_rx is
* configured, and decay_detect_time is reached. */
if (bfd->state == STATE_UP && bfd->decay_min_rx > 0
&& now >= bfd->decay_detect_time) {
bfd_try_decay(bfd);
}
if (bfd->min_tx != bfd->cfg_min_tx
|| (bfd->min_rx != bfd->cfg_min_rx && bfd->min_rx != bfd->decay_min_rx)
|| bfd->in_decay != old_in_decay) {
bfd_poll(bfd);
}
ovs_mutex_unlock(&mutex);
}
bool
bfd_should_send_packet(const struct bfd *bfd) OVS_EXCLUDED(mutex)
{
bool ret;
ovs_mutex_lock(&mutex);
ret = bfd->flags & FLAG_FINAL || time_msec() >= bfd->next_tx;
ovs_mutex_unlock(&mutex);
return ret;
}
void
bfd_put_packet(struct bfd *bfd, struct ofpbuf *p,
uint8_t eth_src[ETH_ADDR_LEN]) OVS_EXCLUDED(mutex)
{
long long int min_tx, min_rx;
struct udp_header *udp;
struct eth_header *eth;
struct ip_header *ip;
struct msg *msg;
ovs_mutex_lock(&mutex);
if (bfd->next_tx) {
long long int delay = time_msec() - bfd->next_tx;
long long int interval = bfd_tx_interval(bfd);
if (delay > interval * 3 / 2) {
VLOG_INFO("%s: long delay of %lldms (expected %lldms) sending BFD"
" control message", bfd->name, delay, interval);
}
}
/* RFC 5880 Section 6.5
* A BFD Control packet MUST NOT have both the Poll (P) and Final (F) bits
* set. */
ovs_assert(!(bfd->flags & FLAG_POLL) || !(bfd->flags & FLAG_FINAL));
ofpbuf_reserve(p, 2); /* Properly align after the ethernet header. */
eth = ofpbuf_put_uninit(p, sizeof *eth);
memcpy(eth->eth_src,
eth_addr_is_zero(bfd->local_eth_src) ? eth_src
: bfd->local_eth_src,
ETH_ADDR_LEN);
memcpy(eth->eth_dst,
eth_addr_is_zero(bfd->local_eth_dst) ? eth_addr_bfd
: bfd->local_eth_dst,
ETH_ADDR_LEN);
eth->eth_type = htons(ETH_TYPE_IP);
ip = ofpbuf_put_zeros(p, sizeof *ip);
ip->ip_ihl_ver = IP_IHL_VER(5, 4);
ip->ip_tot_len = htons(sizeof *ip + sizeof *udp + sizeof *msg);
ip->ip_ttl = MAXTTL;
ip->ip_tos = IPTOS_LOWDELAY | IPTOS_THROUGHPUT;
ip->ip_proto = IPPROTO_UDP;
put_16aligned_be32(&ip->ip_src, bfd->ip_src);
put_16aligned_be32(&ip->ip_dst, bfd->ip_dst);
ip->ip_csum = csum(ip, sizeof *ip);
udp = ofpbuf_put_zeros(p, sizeof *udp);
udp->udp_src = htons(bfd->udp_src);
udp->udp_dst = htons(BFD_DEST_PORT);
udp->udp_len = htons(sizeof *udp + sizeof *msg);
msg = ofpbuf_put_uninit(p, sizeof *msg);
msg->vers_diag = (BFD_VERSION << 5) | bfd->diag;
msg->flags = (bfd->state & STATE_MASK) | bfd->flags;
msg->mult = bfd->mult;
msg->length = BFD_PACKET_LEN;
msg->my_disc = htonl(bfd->disc);
msg->your_disc = htonl(bfd->rmt_disc);
msg->min_rx_echo = htonl(0);
if (bfd_in_poll(bfd)) {
min_tx = bfd->poll_min_tx;
min_rx = bfd->poll_min_rx;
} else {
min_tx = bfd_min_tx(bfd);
min_rx = bfd->min_rx;
}
msg->min_tx = htonl(min_tx * 1000);
msg->min_rx = htonl(min_rx * 1000);
bfd->flags &= ~FLAG_FINAL;
log_msg(VLL_DBG, msg, "Sending BFD Message", bfd);
bfd->last_tx = time_msec();
bfd_set_next_tx(bfd);
ovs_mutex_unlock(&mutex);
}
bool
bfd_should_process_flow(const struct bfd *bfd_, const struct flow *flow,
struct flow_wildcards *wc)
{
struct bfd *bfd = CONST_CAST(struct bfd *, bfd_);
bool check_tnl_key;
memset(&wc->masks.dl_dst, 0xff, sizeof wc->masks.dl_dst);
if (!eth_addr_is_zero(bfd->rmt_eth_dst)
&& memcmp(bfd->rmt_eth_dst, flow->dl_dst, ETH_ADDR_LEN)) {
return false;
}
memset(&wc->masks.nw_proto, 0xff, sizeof wc->masks.nw_proto);
memset(&wc->masks.tp_dst, 0xff, sizeof wc->masks.tp_dst);
atomic_read(&bfd->check_tnl_key, &check_tnl_key);
if (check_tnl_key) {
memset(&wc->masks.tunnel.tun_id, 0xff, sizeof wc->masks.tunnel.tun_id);
}
return (flow->dl_type == htons(ETH_TYPE_IP)
&& flow->nw_proto == IPPROTO_UDP
&& flow->tp_dst == htons(BFD_DEST_PORT)
&& (!check_tnl_key || flow->tunnel.tun_id == htonll(0)));
}
void
bfd_process_packet(struct bfd *bfd, const struct flow *flow,
const struct ofpbuf *p) OVS_EXCLUDED(mutex)
{
uint32_t rmt_min_rx, pkt_your_disc;
enum state rmt_state;
enum flags flags;
uint8_t version;
struct msg *msg;
const uint8_t *l7 = ofpbuf_get_udp_payload(p);
if (!l7) {
return; /* No UDP payload. */
}
/* This function is designed to follow section RFC 5880 6.8.6 closely. */
ovs_mutex_lock(&mutex);
/* Increments the decay rx counter. */
bfd->decay_rx_ctl++;
bfd_forwarding__(bfd);
if (flow->nw_ttl != 255) {
/* XXX Should drop in the kernel to prevent DOS. */
goto out;
}
msg = ofpbuf_at(p, l7 - (uint8_t *)ofpbuf_data(p), BFD_PACKET_LEN);
if (!msg) {
VLOG_INFO_RL(&rl, "%s: Received too-short BFD control message (only "
"%"PRIdPTR" bytes long, at least %d required).",
bfd->name, (uint8_t *) ofpbuf_tail(p) - l7,
BFD_PACKET_LEN);
goto out;
}
/* RFC 5880 Section 6.8.6
* If the Length field is greater than the payload of the encapsulating
* protocol, the packet MUST be discarded.
*
* Note that we make this check implicity. Above we use ofpbuf_at() to
* ensure that there are at least BFD_PACKET_LEN bytes in the payload of
* the encapsulating protocol. Below we require msg->length to be exactly
* BFD_PACKET_LEN bytes. */
flags = msg->flags & FLAGS_MASK;
rmt_state = msg->flags & STATE_MASK;
version = msg->vers_diag >> VERS_SHIFT;
log_msg(VLL_DBG, msg, "Received BFD control message", bfd);
if (version != BFD_VERSION) {
log_msg(VLL_WARN, msg, "Incorrect version", bfd);
goto out;
}
/* Technically this should happen after the length check. We don't support
* authentication however, so it's simpler to do the check first. */
if (flags & FLAG_AUTH) {
log_msg(VLL_WARN, msg, "Authenticated control message with"
" authentication disabled", bfd);
goto out;
}
if (msg->length != BFD_PACKET_LEN) {
log_msg(VLL_WARN, msg, "Unexpected length", bfd);
if (msg->length < BFD_PACKET_LEN) {
goto out;
}
}
if (!msg->mult) {
log_msg(VLL_WARN, msg, "Zero multiplier", bfd);
goto out;
}
if (flags & FLAG_MULTIPOINT) {
log_msg(VLL_WARN, msg, "Unsupported multipoint flag", bfd);
goto out;
}
if (!msg->my_disc) {
log_msg(VLL_WARN, msg, "NULL my_disc", bfd);
goto out;
}
pkt_your_disc = ntohl(msg->your_disc);
if (pkt_your_disc) {
/* Technically, we should use the your discriminator field to figure
* out which 'struct bfd' this packet is destined towards. That way a
* bfd session could migrate from one interface to another
* transparently. This doesn't fit in with the OVS structure very
* well, so in this respect, we are not compliant. */
if (pkt_your_disc != bfd->disc) {
log_msg(VLL_WARN, msg, "Incorrect your_disc", bfd);
goto out;
}
} else if (rmt_state > STATE_DOWN) {
log_msg(VLL_WARN, msg, "Null your_disc", bfd);
goto out;
}
if (bfd->rmt_state != rmt_state) {
bfd_status_changed(bfd);
}
bfd->rmt_disc = ntohl(msg->my_disc);
bfd->rmt_state = rmt_state;
bfd->rmt_flags = flags;
bfd->rmt_diag = msg->vers_diag & DIAG_MASK;
if (flags & FLAG_FINAL && bfd_in_poll(bfd)) {
bfd->min_tx = bfd->poll_min_tx;
bfd->min_rx = bfd->poll_min_rx;
bfd->flags &= ~FLAG_POLL;
log_msg(VLL_INFO, msg, "Poll sequence terminated", bfd);
}
if (flags & FLAG_POLL) {
/* RFC 5880 Section 6.5
* When the other system receives a Poll, it immediately transmits a
* BFD Control packet with the Final (F) bit set, independent of any
* periodic BFD Control packets it may be sending
* (see section 6.8.7). */
bfd->flags &= ~FLAG_POLL;
bfd->flags |= FLAG_FINAL;
}
rmt_min_rx = MAX(ntohl(msg->min_rx) / 1000, 1);
if (bfd->rmt_min_rx != rmt_min_rx) {
bfd->rmt_min_rx = rmt_min_rx;
if (bfd->next_tx) {
bfd_set_next_tx(bfd);
}
log_msg(VLL_INFO, msg, "New remote min_rx", bfd);
}
bfd->rmt_min_tx = MAX(ntohl(msg->min_tx) / 1000, 1);
bfd->detect_time = bfd_rx_interval(bfd) * bfd->mult + time_msec();
if (bfd->state == STATE_ADMIN_DOWN) {
VLOG_DBG_RL(&rl, "Administratively down, dropping control message.");
goto out;
}
if (rmt_state == STATE_ADMIN_DOWN) {
if (bfd->state != STATE_DOWN) {
bfd_set_state(bfd, STATE_DOWN, DIAG_RMT_DOWN);
}
} else {
switch (bfd->state) {
case STATE_DOWN:
if (rmt_state == STATE_DOWN) {
bfd_set_state(bfd, STATE_INIT, bfd->diag);
} else if (rmt_state == STATE_INIT) {
bfd_set_state(bfd, STATE_UP, bfd->diag);
}
break;
case STATE_INIT:
if (rmt_state > STATE_DOWN) {
bfd_set_state(bfd, STATE_UP, bfd->diag);
}
break;
case STATE_UP:
if (rmt_state <= STATE_DOWN) {
bfd_set_state(bfd, STATE_DOWN, DIAG_RMT_DOWN);
log_msg(VLL_INFO, msg, "Remote signaled STATE_DOWN", bfd);
}
break;
case STATE_ADMIN_DOWN:
default:
OVS_NOT_REACHED();
}
}
/* XXX: RFC 5880 Section 6.8.6 Demand mode related calculations here. */
if (bfd->forwarding_if_rx) {
bfd->demand_rx_bfd_time = time_msec() + 100 * bfd->cfg_min_rx;
}
out:
bfd_forwarding__(bfd);
ovs_mutex_unlock(&mutex);
}
/* Must be called when the netdev owned by 'bfd' should change. */
void
bfd_set_netdev(struct bfd *bfd, const struct netdev *netdev)
OVS_EXCLUDED(mutex)
{
ovs_mutex_lock(&mutex);
if (bfd->netdev != netdev) {
netdev_close(bfd->netdev);
bfd->netdev = netdev_ref(netdev);
if (bfd->decay_min_rx && bfd->state == STATE_UP) {
bfd_decay_update(bfd);
}
if (bfd->forwarding_if_rx && bfd->state == STATE_UP) {
bfd_forwarding_if_rx_update(bfd);
}
bfd->rx_packets = bfd_rx_packets(bfd);
}
ovs_mutex_unlock(&mutex);
}
/* Updates the forwarding flag. If override is not configured and
* the forwarding flag value changes, increments the flap count.
*
* Note this function may be called multiple times in a function
* (e.g. bfd_account_rx) before and after the bfd state or status
* change. This is to capture any forwarding flag flap. */
static bool
bfd_forwarding__(struct bfd *bfd) OVS_REQUIRES(mutex)
{
long long int now = time_msec();
bool forwarding_if_rx;
bool last_forwarding = bfd->last_forwarding;
if (bfd->forwarding_override != -1) {
return bfd->forwarding_override == 1;
}
forwarding_if_rx = bfd->forwarding_if_rx
&& bfd->forwarding_if_rx_detect_time > now
&& bfd->demand_rx_bfd_time > now;
bfd->last_forwarding = (bfd->state == STATE_UP || forwarding_if_rx)
&& bfd->rmt_diag != DIAG_PATH_DOWN
&& bfd->rmt_diag != DIAG_CPATH_DOWN
&& bfd->rmt_diag != DIAG_RCPATH_DOWN;
if (bfd->last_forwarding != last_forwarding) {
bfd->flap_count++;
bfd_status_changed(bfd);
}
return bfd->last_forwarding;
}
/* Helpers. */
static bool
bfd_lookup_ip(const char *host_name, struct in_addr *addr)
{
if (!inet_pton(AF_INET, host_name, addr)) {
VLOG_ERR_RL(&rl, "\"%s\" is not a valid IP address", host_name);
return false;
}
return true;
}
static bool
bfd_in_poll(const struct bfd *bfd) OVS_REQUIRES(mutex)
{
return (bfd->flags & FLAG_POLL) != 0;
}
static void
bfd_poll(struct bfd *bfd) OVS_REQUIRES(mutex)
{
if (bfd->state > STATE_DOWN && !bfd_in_poll(bfd)
&& !(bfd->flags & FLAG_FINAL)) {
bfd->poll_min_tx = bfd->cfg_min_tx;
bfd->poll_min_rx = bfd->in_decay ? bfd->decay_min_rx : bfd->cfg_min_rx;
bfd->flags |= FLAG_POLL;
bfd->next_tx = 0;
VLOG_INFO_RL(&rl, "%s: Initiating poll sequence", bfd->name);
}
}
static long long int
bfd_min_tx(const struct bfd *bfd) OVS_REQUIRES(mutex)
{
/* RFC 5880 Section 6.8.3
* When bfd.SessionState is not Up, the system MUST set
* bfd.DesiredMinTxInterval to a value of not less than one second
* (1,000,000 microseconds). This is intended to ensure that the
* bandwidth consumed by BFD sessions that are not Up is negligible,
* particularly in the case where a neighbor may not be running BFD. */
return (bfd->state == STATE_UP ? bfd->min_tx : MAX(bfd->min_tx, 1000));
}
static long long int
bfd_tx_interval(const struct bfd *bfd) OVS_REQUIRES(mutex)
{
long long int interval = bfd_min_tx(bfd);
return MAX(interval, bfd->rmt_min_rx);
}
static long long int
bfd_rx_interval(const struct bfd *bfd) OVS_REQUIRES(mutex)
{
return MAX(bfd->min_rx, bfd->rmt_min_tx);
}
static void
bfd_set_next_tx(struct bfd *bfd) OVS_REQUIRES(mutex)
{
long long int interval = bfd_tx_interval(bfd);
interval -= interval * random_range(26) / 100;
bfd->next_tx = bfd->last_tx + interval;
}
static const char *
bfd_flag_str(enum flags flags)
{