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/*
* Copyright (c) 2008, 2009, 2010, 2011 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.
*/
/* Based on sample implementation in 802.1D-1998. Above copyright and license
* applies to all modifications. */
#include <config.h>
#include "stp.h"
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
#include <inttypes.h>
#include <stdlib.h>
#include "byte-order.h"
#include "ofpbuf.h"
#include "packets.h"
#include "unixctl.h"
#include "util.h"
#include "vlog.h"
VLOG_DEFINE_THIS_MODULE(stp);
#define STP_PROTOCOL_ID 0x0000
#define STP_PROTOCOL_VERSION 0x00
#define STP_TYPE_CONFIG 0x00
#define STP_TYPE_TCN 0x80
struct stp_bpdu_header {
ovs_be16 protocol_id; /* STP_PROTOCOL_ID. */
uint8_t protocol_version; /* STP_PROTOCOL_VERSION. */
uint8_t bpdu_type; /* One of STP_TYPE_*. */
} __attribute__((packed));
BUILD_ASSERT_DECL(sizeof(struct stp_bpdu_header) == 4);
enum stp_config_bpdu_flags {
STP_CONFIG_TOPOLOGY_CHANGE_ACK = 0x80,
STP_CONFIG_TOPOLOGY_CHANGE = 0x01
};
struct stp_config_bpdu {
struct stp_bpdu_header header; /* Type STP_TYPE_CONFIG. */
uint8_t flags; /* STP_CONFIG_* flags. */
ovs_be64 root_id; /* 8.5.1.1: Bridge believed to be root. */
ovs_be32 root_path_cost; /* 8.5.1.2: Cost of path to root. */
ovs_be64 bridge_id; /* 8.5.1.3: ID of transmitting bridge. */
ovs_be16 port_id; /* 8.5.1.4: Port transmitting the BPDU. */
ovs_be16 message_age; /* 8.5.1.5: Age of BPDU at tx time. */
ovs_be16 max_age; /* 8.5.1.6: Timeout for received data. */
ovs_be16 hello_time; /* 8.5.1.7: Time between BPDU generation. */
ovs_be16 forward_delay; /* 8.5.1.8: State progression delay. */
} __attribute__((packed));
BUILD_ASSERT_DECL(sizeof(struct stp_config_bpdu) == 35);
struct stp_tcn_bpdu {
struct stp_bpdu_header header; /* Type STP_TYPE_TCN. */
} __attribute__((packed));
BUILD_ASSERT_DECL(sizeof(struct stp_tcn_bpdu) == 4);
struct stp_timer {
bool active; /* Timer in use? */
int value; /* Current value of timer, counting up. */
};
struct stp_port {
struct stp *stp;
void *aux; /* Auxiliary data the user may retrieve. */
int port_id; /* 8.5.5.1: Unique port identifier. */
enum stp_state state; /* 8.5.5.2: Current state. */
int path_cost; /* 8.5.5.3: Cost of tx/rx on this port. */
stp_identifier designated_root; /* 8.5.5.4. */
int designated_cost; /* 8.5.5.5: Path cost to root on port. */
stp_identifier designated_bridge; /* 8.5.5.6. */
int designated_port; /* 8.5.5.7: Port to send config msgs on. */
bool topology_change_ack; /* 8.5.5.8: Flag for next config BPDU. */
bool config_pending; /* 8.5.5.9: Send BPDU when hold expires? */
bool change_detection_enabled; /* 8.5.5.10: Detect topology changes? */
struct stp_timer message_age_timer; /* 8.5.6.1: Age of received info. */
struct stp_timer forward_delay_timer; /* 8.5.6.2: State change timer. */
struct stp_timer hold_timer; /* 8.5.6.3: BPDU rate limit timer. */
int tx_count; /* Number of BPDUs transmitted. */
int rx_count; /* Number of valid BPDUs received. */
int error_count; /* Number of bad BPDUs received. */
bool state_changed;
};
struct stp {
struct list node; /* Node in all_stps list. */
/* Static bridge data. */
char *name; /* Human-readable name for log messages. */
stp_identifier bridge_id; /* 8.5.3.7: This bridge. */
int max_age; /* 8.5.3.4: Time to drop received data. */
int hello_time; /* 8.5.3.5: Time between sending BPDUs. */
int forward_delay; /* 8.5.3.6: Delay between state changes. */
int bridge_max_age; /* 8.5.3.8: max_age when we're root. */
int bridge_hello_time; /* 8.5.3.9: hello_time as root. */
int bridge_forward_delay; /* 8.5.3.10: forward_delay as root. */
int rq_max_age; /* User-requested max age, in ms. */
int rq_hello_time; /* User-requested hello time, in ms. */
int rq_forward_delay; /* User-requested forward delay, in ms. */
int elapsed_remainder; /* Left-over msecs from last stp_tick(). */
/* Dynamic bridge data. */
stp_identifier designated_root; /* 8.5.3.1: Bridge believed to be root. */
unsigned int root_path_cost; /* 8.5.3.2: Cost of path to root. */
struct stp_port *root_port; /* 8.5.3.3: Lowest cost port to root. */
bool topology_change_detected; /* 8.5.3.11: Detected a topology change? */
bool topology_change; /* 8.5.3.12: Received topology change? */
/* Bridge timers. */
struct stp_timer hello_timer; /* 8.5.4.1: Hello timer. */
struct stp_timer tcn_timer; /* 8.5.4.2: Topology change timer. */
struct stp_timer topology_change_timer; /* 8.5.4.3. */
/* Ports. */
struct stp_port ports[STP_MAX_PORTS];
/* Interface to client. */
bool fdb_needs_flush; /* MAC learning tables needs flushing. */
struct stp_port *first_changed_port;
void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux);
void *aux;
};
static struct list all_stps = LIST_INITIALIZER(&all_stps);
#define FOR_EACH_ENABLED_PORT(PORT, STP) \
for ((PORT) = stp_next_enabled_port((STP), (STP)->ports); \
(PORT); \
(PORT) = stp_next_enabled_port((STP), (PORT) + 1))
static struct stp_port *
stp_next_enabled_port(const struct stp *stp, const struct stp_port *port)
{
for (; port < &stp->ports[ARRAY_SIZE(stp->ports)]; port++) {
if (port->state != STP_DISABLED) {
return (struct stp_port *) port;
}
}
return NULL;
}
#define MESSAGE_AGE_INCREMENT 1
static void stp_transmit_config(struct stp_port *);
static bool stp_supersedes_port_info(const struct stp_port *,
const struct stp_config_bpdu *);
static void stp_record_config_information(struct stp_port *,
const struct stp_config_bpdu *);
static void stp_record_config_timeout_values(struct stp *,
const struct stp_config_bpdu *);
static bool stp_is_designated_port(const struct stp_port *);
static void stp_config_bpdu_generation(struct stp *);
static void stp_transmit_tcn(struct stp *);
static void stp_configuration_update(struct stp *);
static bool stp_supersedes_root(const struct stp_port *root,
const struct stp_port *);
static void stp_root_selection(struct stp *);
static void stp_designated_port_selection(struct stp *);
static void stp_become_designated_port(struct stp_port *);
static void stp_port_state_selection(struct stp *);
static void stp_make_forwarding(struct stp_port *);
static void stp_make_blocking(struct stp_port *);
static void stp_set_port_state(struct stp_port *, enum stp_state);
static void stp_topology_change_detection(struct stp *);
static void stp_topology_change_acknowledged(struct stp *);
static void stp_acknowledge_topology_change(struct stp_port *);
static void stp_received_config_bpdu(struct stp *, struct stp_port *,
const struct stp_config_bpdu *);
static void stp_received_tcn_bpdu(struct stp *, struct stp_port *);
static void stp_hello_timer_expiry(struct stp *);
static void stp_message_age_timer_expiry(struct stp_port *);
static bool stp_is_designated_for_some_port(const struct stp *);
static void stp_forward_delay_timer_expiry(struct stp_port *);
static void stp_tcn_timer_expiry(struct stp *);
static void stp_topology_change_timer_expiry(struct stp *);
static void stp_hold_timer_expiry(struct stp_port *);
static void stp_initialize_port(struct stp_port *, enum stp_state);
static void stp_become_root_bridge(struct stp *);
static void stp_update_bridge_timers(struct stp *);
static int clamp(int x, int min, int max);
static int ms_to_timer(int ms);
static int timer_to_ms(int timer);
static void stp_start_timer(struct stp_timer *, int value);
static void stp_stop_timer(struct stp_timer *);
static bool stp_timer_expired(struct stp_timer *, int elapsed, int timeout);
static void stp_send_bpdu(struct stp_port *, const void *, size_t);
static void stp_unixctl_tcn(struct unixctl_conn *, int argc,
const char *argv[], void *aux);
void
stp_init(void)
{
unixctl_command_register("stp/tcn", "[bridge]", 0, 1, stp_unixctl_tcn,
NULL);
}
/* Creates and returns a new STP instance that initially has no ports enabled.
*
* 'bridge_id' should be a 48-bit MAC address as returned by
* eth_addr_to_uint64(). 'bridge_id' may also have a priority value in its top
* 16 bits; if those bits are set to 0, STP_DEFAULT_BRIDGE_PRIORITY is used.
* (This priority may be changed with stp_set_bridge_priority().)
*
* When the bridge needs to send out a BPDU, it calls 'send_bpdu'. This
* callback may be called from stp_tick() or stp_received_bpdu(). The
* arguments to 'send_bpdu' are an STP BPDU encapsulated in 'bpdu',
* the spanning tree port number 'port_no' that should transmit the
* packet, and auxiliary data to be passed to the callback in 'aux'.
*/
struct stp *
stp_create(const char *name, stp_identifier bridge_id,
void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux),
void *aux)
{
struct stp *stp;
struct stp_port *p;
stp = xzalloc(sizeof *stp);
stp->name = xstrdup(name);
stp->bridge_id = bridge_id;
if (!(stp->bridge_id >> 48)) {
stp->bridge_id |= (uint64_t) STP_DEFAULT_BRIDGE_PRIORITY << 48;
}
stp->rq_max_age = STP_DEFAULT_MAX_AGE;
stp->rq_hello_time = STP_DEFAULT_HELLO_TIME;
stp->rq_forward_delay = STP_DEFAULT_FWD_DELAY;
stp_update_bridge_timers(stp);
stp->max_age = stp->bridge_max_age;
stp->hello_time = stp->bridge_hello_time;
stp->forward_delay = stp->bridge_forward_delay;
stp->designated_root = stp->bridge_id;
stp->root_path_cost = 0;
stp->root_port = NULL;
stp->topology_change_detected = false;
stp->topology_change = false;
stp_stop_timer(&stp->tcn_timer);
stp_stop_timer(&stp->topology_change_timer);
stp_start_timer(&stp->hello_timer, 0);
stp->send_bpdu = send_bpdu;
stp->aux = aux;
stp->first_changed_port = &stp->ports[ARRAY_SIZE(stp->ports)];
for (p = stp->ports; p < &stp->ports[ARRAY_SIZE(stp->ports)]; p++) {
p->stp = stp;
p->port_id = (stp_port_no(p) + 1) | (STP_DEFAULT_PORT_PRIORITY << 8);
p->path_cost = 19; /* Recommended default for 100 Mb/s link. */
stp_initialize_port(p, STP_DISABLED);
}
list_push_back(&all_stps, &stp->node);
return stp;
}
/* Destroys 'stp'. */
void
stp_destroy(struct stp *stp)
{
if (stp) {
list_remove(&stp->node);
free(stp->name);
free(stp);
}
}
/* Runs 'stp' given that 'ms' milliseconds have passed. */
void
stp_tick(struct stp *stp, int ms)
{
struct stp_port *p;
int elapsed;
/* Convert 'ms' to STP timer ticks. Preserve any leftover milliseconds
* from previous stp_tick() calls so that we don't lose STP ticks when we
* are called too frequently. */
ms = clamp(ms, 0, INT_MAX - 1000) + stp->elapsed_remainder;
elapsed = ms_to_timer(ms);
stp->elapsed_remainder = ms - timer_to_ms(elapsed);
if (!elapsed) {
return;
}
if (stp_timer_expired(&stp->hello_timer, elapsed, stp->hello_time)) {
stp_hello_timer_expiry(stp);
}
if (stp_timer_expired(&stp->tcn_timer, elapsed, stp->bridge_hello_time)) {
stp_tcn_timer_expiry(stp);
}
if (stp_timer_expired(&stp->topology_change_timer, elapsed,
stp->max_age + stp->forward_delay)) {
stp_topology_change_timer_expiry(stp);
}
FOR_EACH_ENABLED_PORT (p, stp) {
if (stp_timer_expired(&p->message_age_timer, elapsed, stp->max_age)) {
stp_message_age_timer_expiry(p);
}
}
FOR_EACH_ENABLED_PORT (p, stp) {
if (stp_timer_expired(&p->forward_delay_timer, elapsed,
stp->forward_delay)) {
stp_forward_delay_timer_expiry(p);
}
if (stp_timer_expired(&p->hold_timer, elapsed, ms_to_timer(1000))) {
stp_hold_timer_expiry(p);
}
}
}
static void
set_bridge_id(struct stp *stp, stp_identifier new_bridge_id)
{
if (new_bridge_id != stp->bridge_id) {
bool root;
struct stp_port *p;
root = stp_is_root_bridge(stp);
FOR_EACH_ENABLED_PORT (p, stp) {
if (stp_is_designated_port(p)) {
p->designated_bridge = new_bridge_id;
}
}
stp->bridge_id = new_bridge_id;
stp_configuration_update(stp);
stp_port_state_selection(stp);
if (stp_is_root_bridge(stp) && !root) {
stp_become_root_bridge(stp);
}
}
}
void
stp_set_bridge_id(struct stp *stp, stp_identifier bridge_id)
{
const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
const uint64_t pri_bits = ~mac_bits;
set_bridge_id(stp, (stp->bridge_id & pri_bits) | (bridge_id & mac_bits));
}
void
stp_set_bridge_priority(struct stp *stp, uint16_t new_priority)
{
const uint64_t mac_bits = (UINT64_C(1) << 48) - 1;
set_bridge_id(stp, ((stp->bridge_id & mac_bits)
| ((uint64_t) new_priority << 48)));
}
/* Sets the desired hello time for 'stp' to 'ms', in milliseconds. The actual
* hello time is clamped to the range of 1 to 10 seconds and subject to the
* relationship (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge
* hello time is only used when 'stp' is the root bridge. */
void
stp_set_hello_time(struct stp *stp, int ms)
{
stp->rq_hello_time = ms;
stp_update_bridge_timers(stp);
}
/* Sets the desired max age for 'stp' to 'ms', in milliseconds. The actual max
* age is clamped to the range of 6 to 40 seconds and subject to the
* relationships (2 * (bridge_forward_delay - 1 s) >= bridge_max_age) and
* (bridge_max_age >= 2 * (bridge_hello_time + 1 s)). The bridge max age is
* only used when 'stp' is the root bridge. */
void
stp_set_max_age(struct stp *stp, int ms)
{
stp->rq_max_age = ms;
stp_update_bridge_timers(stp);
}
/* Sets the desired forward delay for 'stp' to 'ms', in milliseconds. The
* actual forward delay is clamped to the range of 4 to 30 seconds and subject
* to the relationship (2 * (bridge_forward_delay - 1 s) >= bridge_max_age).
* The bridge forward delay is only used when 'stp' is the root bridge. */
void
stp_set_forward_delay(struct stp *stp, int ms)
{
stp->rq_forward_delay = ms;
stp_update_bridge_timers(stp);
}
/* Returns the name given to 'stp' in the call to stp_create(). */
const char *
stp_get_name(const struct stp *stp)
{
return stp->name;
}
/* Returns the bridge ID for 'stp'. */
stp_identifier
stp_get_bridge_id(const struct stp *stp)
{
return stp->bridge_id;
}
/* Returns the bridge ID of the bridge currently believed to be the root. */
stp_identifier
stp_get_designated_root(const struct stp *stp)
{
return stp->designated_root;
}
/* Returns true if 'stp' believes itself to the be root of the spanning tree,
* false otherwise. */
bool
stp_is_root_bridge(const struct stp *stp)
{
return stp->bridge_id == stp->designated_root;
}
/* Returns the cost of the path from 'stp' to the root of the spanning tree. */
int
stp_get_root_path_cost(const struct stp *stp)
{
return stp->root_path_cost;
}
/* Returns the bridge hello time, in ms. The returned value is not necessarily
* the value passed to stp_set_hello_time(): it is clamped to the valid range
* and quantized to the STP timer resolution. */
int
stp_get_hello_time(const struct stp *stp)
{
return timer_to_ms(stp->bridge_hello_time);
}
/* Returns the bridge max age, in ms. The returned value is not necessarily
* the value passed to stp_set_max_age(): it is clamped to the valid range,
* quantized to the STP timer resolution, and adjusted to match the constraints
* due to the hello time. */
int
stp_get_max_age(const struct stp *stp)
{
return timer_to_ms(stp->bridge_max_age);
}
/* Returns the bridge forward delay, in ms. The returned value is not
* necessarily the value passed to stp_set_forward_delay(): it is clamped to
* the valid range, quantized to the STP timer resolution, and adjusted to
* match the constraints due to the forward delay. */
int
stp_get_forward_delay(const struct stp *stp)
{
return timer_to_ms(stp->bridge_forward_delay);
}
/* Returns true if something has happened to 'stp' which necessitates flushing
* the client's MAC learning table. Calling this function resets 'stp' so that
* future calls will return false until flushing is required again. */
bool
stp_check_and_reset_fdb_flush(struct stp *stp)
{
bool needs_flush = stp->fdb_needs_flush;
stp->fdb_needs_flush = false;
return needs_flush;
}
/* Returns the port in 'stp' with index 'port_no', which must be between 0 and
* STP_MAX_PORTS. */
struct stp_port *
stp_get_port(struct stp *stp, int port_no)
{
assert(port_no >= 0 && port_no < ARRAY_SIZE(stp->ports));
return &stp->ports[port_no];
}
/* Returns the port connecting 'stp' to the root bridge, or a null pointer if
* there is no such port. */
struct stp_port *
stp_get_root_port(struct stp *stp)
{
return stp->root_port;
}
/* Finds a port whose state has changed. If successful, stores the port whose
* state changed in '*portp' and returns true. If no port has changed, stores
* NULL in '*portp' and returns false. */
bool
stp_get_changed_port(struct stp *stp, struct stp_port **portp)
{
struct stp_port *end = &stp->ports[ARRAY_SIZE(stp->ports)];
struct stp_port *p;
for (p = stp->first_changed_port; p < end; p++) {
if (p->state_changed) {
p->state_changed = false;
stp->first_changed_port = p + 1;
*portp = p;
return true;
}
}
stp->first_changed_port = end;
*portp = NULL;
return false;
}
/* Returns the name for the given 'state' (for use in debugging and log
* messages). */
const char *
stp_state_name(enum stp_state state)
{
switch (state) {
case STP_DISABLED:
return "disabled";
case STP_LISTENING:
return "listening";
case STP_LEARNING:
return "learning";
case STP_FORWARDING:
return "forwarding";
case STP_BLOCKING:
return "blocking";
default:
NOT_REACHED();
}
}
/* Returns true if 'state' is one in which packets received on a port should
* be forwarded, false otherwise.
*
* Returns true if 'state' is STP_DISABLED, since presumably in that case the
* port should still work, just not have STP applied to it. */
bool
stp_forward_in_state(enum stp_state state)
{
return (state & (STP_DISABLED | STP_FORWARDING)) != 0;
}
/* Returns true if 'state' is one in which MAC learning should be done on
* packets received on a port, false otherwise.
*
* Returns true if 'state' is STP_DISABLED, since presumably in that case the
* port should still work, just not have STP applied to it. */
bool
stp_learn_in_state(enum stp_state state)
{
return (state & (STP_DISABLED | STP_LEARNING | STP_FORWARDING)) != 0;
}
/* Returns the name for the given 'role' (for use in debugging and log
* messages). */
const char *
stp_role_name(enum stp_role role)
{
switch (role) {
case STP_ROLE_ROOT:
return "root";
case STP_ROLE_DESIGNATED:
return "designated";
case STP_ROLE_ALTERNATE:
return "alternate";
case STP_ROLE_DISABLED:
return "disabled";
default:
NOT_REACHED();
}
}
/* Notifies the STP entity that bridge protocol data unit 'bpdu', which is
* 'bpdu_size' bytes in length, was received on port 'p'.
*
* This function may call the 'send_bpdu' function provided to stp_create(). */
void
stp_received_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
{
struct stp *stp = p->stp;
const struct stp_bpdu_header *header;
if (p->state == STP_DISABLED) {
return;
}
if (bpdu_size < sizeof(struct stp_bpdu_header)) {
VLOG_WARN("%s: received runt %zu-byte BPDU", stp->name, bpdu_size);
p->error_count++;
return;
}
header = bpdu;
if (header->protocol_id != htons(STP_PROTOCOL_ID)) {
VLOG_WARN("%s: received BPDU with unexpected protocol ID %"PRIu16,
stp->name, ntohs(header->protocol_id));
p->error_count++;
return;
}
if (header->protocol_version != STP_PROTOCOL_VERSION) {
VLOG_DBG("%s: received BPDU with unexpected protocol version %"PRIu8,
stp->name, header->protocol_version);
}
switch (header->bpdu_type) {
case STP_TYPE_CONFIG:
if (bpdu_size < sizeof(struct stp_config_bpdu)) {
VLOG_WARN("%s: received config BPDU with invalid size %zu",
stp->name, bpdu_size);
p->error_count++;
return;
}
stp_received_config_bpdu(stp, p, bpdu);
break;
case STP_TYPE_TCN:
if (bpdu_size != sizeof(struct stp_tcn_bpdu)) {
VLOG_WARN("%s: received TCN BPDU with invalid size %zu",
stp->name, bpdu_size);
p->error_count++;
return;
}
stp_received_tcn_bpdu(stp, p);
break;
default:
VLOG_WARN("%s: received BPDU of unexpected type %"PRIu8,
stp->name, header->bpdu_type);
p->error_count++;
return;
}
p->rx_count++;
}
/* Returns the STP entity in which 'p' is nested. */
struct stp *
stp_port_get_stp(struct stp_port *p)
{
return p->stp;
}
/* Sets the 'aux' member of 'p'.
*
* The 'aux' member will be reset to NULL when stp_port_disable() is
* called or stp_port_enable() is called when the port is in a Disabled
* state. */
void
stp_port_set_aux(struct stp_port *p, void *aux)
{
p->aux = aux;
}
/* Returns the 'aux' member of 'p'. */
void *
stp_port_get_aux(struct stp_port *p)
{
return p->aux;
}
/* Returns the index of port 'p' within its bridge. */
int
stp_port_no(const struct stp_port *p)
{
struct stp *stp = p->stp;
assert(p >= stp->ports && p < &stp->ports[ARRAY_SIZE(stp->ports)]);
return p - stp->ports;
}
/* Returns the port ID for 'p'. */
int
stp_port_get_id(const struct stp_port *p)
{
return p->port_id;
}
/* Returns the state of port 'p'. */
enum stp_state
stp_port_get_state(const struct stp_port *p)
{
return p->state;
}
/* Returns the role of port 'p'. */
enum stp_role
stp_port_get_role(const struct stp_port *p)
{
struct stp_port *root_port = stp_get_root_port(p->stp);
if (root_port && root_port->port_id == p->port_id) {
return STP_ROLE_ROOT;
} else if (stp_is_designated_port(p)) {
return STP_ROLE_DESIGNATED;
} else if (p->state == STP_DISABLED) {
return STP_ROLE_DISABLED;
} else {
return STP_ROLE_ALTERNATE;
}
}
/* Retrieves BPDU transmit and receive counts for 'p'. */
void stp_port_get_counts(const struct stp_port *p,
int *tx_count, int *rx_count, int *error_count)
{
*tx_count = p->tx_count;
*rx_count = p->rx_count;
*error_count = p->error_count;
}
/* Disables STP on port 'p'. */
void
stp_port_disable(struct stp_port *p)
{
struct stp *stp = p->stp;
if (p->state != STP_DISABLED) {
bool root = stp_is_root_bridge(stp);
stp_become_designated_port(p);
stp_set_port_state(p, STP_DISABLED);
p->topology_change_ack = false;
p->config_pending = false;
stp_stop_timer(&p->message_age_timer);
stp_stop_timer(&p->forward_delay_timer);
stp_configuration_update(stp);
stp_port_state_selection(stp);
if (stp_is_root_bridge(stp) && !root) {
stp_become_root_bridge(stp);
}
p->aux = NULL;
}
}
/* Enables STP on port 'p'. The port will initially be in "blocking" state. */
void
stp_port_enable(struct stp_port *p)
{
if (p->state == STP_DISABLED) {
stp_initialize_port(p, STP_BLOCKING);
stp_port_state_selection(p->stp);
}
}
/* Sets the priority of port 'p' to 'new_priority'. Lower numerical values
* are interpreted as higher priorities. */
void
stp_port_set_priority(struct stp_port *p, uint8_t new_priority)
{
uint16_t new_port_id = (p->port_id & 0xff) | (new_priority << 8);
if (p->port_id != new_port_id) {
struct stp *stp = p->stp;
if (stp_is_designated_port(p)) {
p->designated_port = new_port_id;
}
p->port_id = new_port_id;
if (stp->bridge_id == p->designated_bridge
&& p->port_id < p->designated_port) {
stp_become_designated_port(p);
stp_port_state_selection(stp);
}
}
}
/* Convert 'speed' (measured in Mb/s) into the path cost. */
uint16_t
stp_convert_speed_to_cost(unsigned int speed)
{
return speed >= 10000 ? 2 /* 10 Gb/s. */
: speed >= 1000 ? 4 /* 1 Gb/s. */
: speed >= 100 ? 19 /* 100 Mb/s. */
: speed >= 16 ? 62 /* 16 Mb/s. */
: speed >= 10 ? 100 /* 10 Mb/s. */
: speed >= 4 ? 250 /* 4 Mb/s. */
: 19; /* 100 Mb/s (guess). */
}
/* Sets the path cost of port 'p' to 'path_cost'. Lower values are generally
* used to indicate faster links. Use stp_port_set_speed() to automatically
* generate a default path cost from a link speed. */
void
stp_port_set_path_cost(struct stp_port *p, uint16_t path_cost)
{
if (p->path_cost != path_cost) {
struct stp *stp = p->stp;
p->path_cost = path_cost;
stp_configuration_update(stp);
stp_port_state_selection(stp);
}
}
/* Sets the path cost of port 'p' based on 'speed' (measured in Mb/s). */
void
stp_port_set_speed(struct stp_port *p, unsigned int speed)
{
stp_port_set_path_cost(p, stp_convert_speed_to_cost(speed));
}
/* Enables topology change detection on port 'p'. */
void
stp_port_enable_change_detection(struct stp_port *p)
{
p->change_detection_enabled = true;
}
/* Disables topology change detection on port 'p'. */
void
stp_port_disable_change_detection(struct stp_port *p)
{
p->change_detection_enabled = false;
}
static void
stp_transmit_config(struct stp_port *p)
{
struct stp *stp = p->stp;
bool root = stp_is_root_bridge(stp);
if (!root && !stp->root_port) {
return;
}
if (p->hold_timer.active) {
p->config_pending = true;
} else {
struct stp_config_bpdu config;
memset(&config, 0, sizeof config);
config.header.protocol_id = htons(STP_PROTOCOL_ID);
config.header.protocol_version = STP_PROTOCOL_VERSION;
config.header.bpdu_type = STP_TYPE_CONFIG;
config.flags = 0;
if (p->topology_change_ack) {
config.flags |= STP_CONFIG_TOPOLOGY_CHANGE_ACK;
}
if (stp->topology_change) {
config.flags |= STP_CONFIG_TOPOLOGY_CHANGE;
}
config.root_id = htonll(stp->designated_root);
config.root_path_cost = htonl(stp->root_path_cost);
config.bridge_id = htonll(stp->bridge_id);
config.port_id = htons(p->port_id);
if (root) {
config.message_age = htons(0);
} else {
config.message_age = htons(stp->root_port->message_age_timer.value
+ MESSAGE_AGE_INCREMENT);
}
config.max_age = htons(stp->max_age);
config.hello_time = htons(stp->hello_time);
config.forward_delay = htons(stp->forward_delay);
if (ntohs(config.message_age) < stp->max_age) {
p->topology_change_ack = false;
p->config_pending = false;
stp_send_bpdu(p, &config, sizeof config);
stp_start_timer(&p->hold_timer, 0);
}
}
}
static bool
stp_supersedes_port_info(const struct stp_port *p,
const struct stp_config_bpdu *config)
{
if (ntohll(config->root_id) != p->designated_root) {
return ntohll(config->root_id) < p->designated_root;
} else if (ntohl(config->root_path_cost) != p->designated_cost) {
return ntohl(config->root_path_cost) < p->designated_cost;
} else if (ntohll(config->bridge_id) != p->designated_bridge) {
return ntohll(config->bridge_id) < p->designated_bridge;
} else {
return (ntohll(config->bridge_id) != p->stp->bridge_id
|| ntohs(config->port_id) <= p->designated_port);
}
}
static void
stp_record_config_information(struct stp_port *p,
const struct stp_config_bpdu *config)
{
p->designated_root = ntohll(config->root_id);
p->designated_cost = ntohl(config->root_path_cost);
p->designated_bridge = ntohll(config->bridge_id);
p->designated_port = ntohs(config->port_id);
stp_start_timer(&p->message_age_timer, ntohs(config->message_age));
}
static void
stp_record_config_timeout_values(struct stp *stp,
const struct stp_config_bpdu *config)
{
stp->max_age = ntohs(config->max_age);
stp->hello_time = ntohs(config->hello_time);
stp->forward_delay = ntohs(config->forward_delay);
stp->topology_change = config->flags & STP_CONFIG_TOPOLOGY_CHANGE;
}
static bool
stp_is_designated_port(const struct stp_port *p)
{
return (p->designated_bridge == p->stp->bridge_id
&& p->designated_port == p->port_id);
}
static void
stp_config_bpdu_generation(struct stp *stp)
{
struct stp_port *p;
FOR_EACH_ENABLED_PORT (p, stp) {
if (stp_is_designated_port(p)) {
stp_transmit_config(p);
}
}
}
static void
stp_transmit_tcn(struct stp *stp)
{
struct stp_port *p = stp->root_port;
struct stp_tcn_bpdu tcn_bpdu;
if (!p) {
return;
}
tcn_bpdu.header.protocol_id = htons(STP_PROTOCOL_ID);
tcn_bpdu.header.protocol_version = STP_PROTOCOL_VERSION;
tcn_bpdu.header.bpdu_type = STP_TYPE_TCN;
stp_send_bpdu(p, &tcn_bpdu, sizeof tcn_bpdu);
}
static void
stp_configuration_update(struct stp *stp)
{
stp_root_selection(stp);
stp_designated_port_selection(stp);
}
static bool
stp_supersedes_root(const struct stp_port *root, const struct stp_port *p)
{
int p_cost = p->designated_cost + p->path_cost;
int root_cost = root->designated_cost + root->path_cost;
if (p->designated_root != root->designated_root) {
return p->designated_root < root->designated_root;
} else if (p_cost != root_cost) {
return p_cost < root_cost;
} else if (p->designated_bridge != root->designated_bridge) {
return p->designated_bridge < root->designated_bridge;
} else if (p->designated_port != root->designated_port) {
return p->designated_port < root->designated_port;
} else {
return p->port_id < root->port_id;
}
}
static void
stp_root_selection(struct stp *stp)
{
struct stp_port *p, *root;
root = NULL;
FOR_EACH_ENABLED_PORT (p, stp) {
if (stp_is_designated_port(p)
|| p->designated_root >= stp->bridge_id) {
continue;
}
if (root && !stp_supersedes_root(root, p)) {
continue;
}
root = p;
}
stp->root_port = root;
if (!root) {
stp->designated_root = stp->bridge_id;
stp->root_path_cost = 0;
} else {
stp->designated_root = root->designated_root;
stp->root_path_cost = root->designated_cost + root->path_cost;
}
}
static void
stp_designated_port_selection(struct stp *stp)
{
struct stp_port *p;
FOR_EACH_ENABLED_PORT (p, stp) {
if (stp_is_designated_port(p)
|| p->designated_root != stp->designated_root
|| stp->root_path_cost < p->designated_cost
|| (stp->root_path_cost == p->designated_cost
&& (stp->bridge_id < p->designated_bridge
|| (stp->bridge_id == p->designated_bridge
&& p->port_id <= p->designated_port))))
{
stp_become_designated_port(p);
}
}
}
static void
stp_become_designated_port(struct stp_port *p)
{
struct stp *stp = p->stp;
p->designated_root = stp->designated_root;
p->designated_cost = stp->root_path_cost;
p->designated_bridge = stp->bridge_id;
p->designated_port = p->port_id;
}
static void
stp_port_state_selection(struct stp *stp)
{
struct stp_port *p;
FOR_EACH_ENABLED_PORT (p, stp) {
if (p == stp->root_port) {
p->config_pending = false;
p->topology_change_ack = false;
stp_make_forwarding(p);
} else if (stp_is_designated_port(p)) {
stp_stop_timer(&p->message_age_timer);
stp_make_forwarding(p);
} else {
p->config_pending = false;
p->topology_change_ack = false;
stp_make_blocking(p);
}
}
}
static void
stp_make_forwarding(struct stp_port *p)
{
if (p->state == STP_BLOCKING) {
stp_set_port_state(p, STP_LISTENING);
stp_start_timer(&p->forward_delay_timer, 0);
}
}
static void
stp_make_blocking(struct stp_port *p)
{
if (!(p->state & (STP_DISABLED | STP_BLOCKING))) {
if (p->state & (STP_FORWARDING | STP_LEARNING)) {
if (p->change_detection_enabled) {
stp_topology_change_detection(p->stp);
}
}
stp_set_port_state(p, STP_BLOCKING);
stp_stop_timer(&p->forward_delay_timer);
}
}
static void
stp_set_port_state(struct stp_port *p, enum stp_state state)
{
if (state != p->state && !p->state_changed) {
p->state_changed = true;
if (p < p->stp->first_changed_port) {
p->stp->first_changed_port = p;
}
}
p->state = state;
}
static void
stp_topology_change_detection(struct stp *stp)
{
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
if (stp_is_root_bridge(stp)) {
stp->topology_change = true;
stp_start_timer(&stp->topology_change_timer, 0);
} else if (!stp->topology_change_detected) {
stp_transmit_tcn(stp);
stp_start_timer(&stp->tcn_timer, 0);
}
stp->fdb_needs_flush = true;
stp->topology_change_detected = true;
VLOG_INFO_RL(&rl, "%s: detected topology change.", stp->name);
}
static void
stp_topology_change_acknowledged(struct stp *stp)
{
stp->topology_change_detected = false;
stp_stop_timer(&stp->tcn_timer);
}
static void
stp_acknowledge_topology_change(struct stp_port *p)
{
p->topology_change_ack = true;
stp_transmit_config(p);
}
static void
stp_received_config_bpdu(struct stp *stp, struct stp_port *p,
const struct stp_config_bpdu *config)
{
if (ntohs(config->message_age) >= ntohs(config->max_age)) {
VLOG_WARN("%s: received config BPDU with message age (%u) greater "
"than max age (%u)",
stp->name,
ntohs(config->message_age), ntohs(config->max_age));
return;
}
if (p->state != STP_DISABLED) {
bool root = stp_is_root_bridge(stp);
if (stp_supersedes_port_info(p, config)) {
stp_record_config_information(p, config);
stp_configuration_update(stp);
stp_port_state_selection(stp);
if (!stp_is_root_bridge(stp) && root) {
stp_stop_timer(&stp->hello_timer);
if (stp->topology_change_detected) {
stp_stop_timer(&stp->topology_change_timer);
stp_transmit_tcn(stp);
stp_start_timer(&stp->tcn_timer, 0);
}
}
if (p == stp->root_port) {
stp_record_config_timeout_values(stp, config);
stp_config_bpdu_generation(stp);
if (config->flags & STP_CONFIG_TOPOLOGY_CHANGE_ACK) {
stp_topology_change_acknowledged(stp);
}
if (config->flags & STP_CONFIG_TOPOLOGY_CHANGE) {
stp->fdb_needs_flush = true;
}
}
} else if (stp_is_designated_port(p)) {
stp_transmit_config(p);
}
}
}
static void
stp_received_tcn_bpdu(struct stp *stp, struct stp_port *p)
{
if (p->state != STP_DISABLED) {
if (stp_is_designated_port(p)) {
stp_topology_change_detection(stp);
stp_acknowledge_topology_change(p);
}
}
}
static void
stp_hello_timer_expiry(struct stp *stp)
{
stp_config_bpdu_generation(stp);
stp_start_timer(&stp->hello_timer, 0);
}
static void
stp_message_age_timer_expiry(struct stp_port *p)
{
struct stp *stp = p->stp;
bool root = stp_is_root_bridge(stp);
stp_become_designated_port(p);
stp_configuration_update(stp);
stp_port_state_selection(stp);
if (stp_is_root_bridge(stp) && !root) {
stp->max_age = stp->bridge_max_age;
stp->hello_time = stp->bridge_hello_time;
stp->forward_delay = stp->bridge_forward_delay;
stp_topology_change_detection(stp);
stp_stop_timer(&stp->tcn_timer);
stp_config_bpdu_generation(stp);
stp_start_timer(&stp->hello_timer, 0);
}
}
static bool
stp_is_designated_for_some_port(const struct stp *stp)
{
const struct stp_port *p;
FOR_EACH_ENABLED_PORT (p, stp) {
if (p->designated_bridge == stp->bridge_id) {
return true;
}
}
return false;
}
static void
stp_forward_delay_timer_expiry(struct stp_port *p)
{
if (p->state == STP_LISTENING) {
stp_set_port_state(p, STP_LEARNING);
stp_start_timer(&p->forward_delay_timer, 0);
} else if (p->state == STP_LEARNING) {
stp_set_port_state(p, STP_FORWARDING);
if (stp_is_designated_for_some_port(p->stp)) {
if (p->change_detection_enabled) {
stp_topology_change_detection(p->stp);
}
}
}
}
static void
stp_tcn_timer_expiry(struct stp *stp)
{
stp_transmit_tcn(stp);
stp_start_timer(&stp->tcn_timer, 0);
}
static void
stp_topology_change_timer_expiry(struct stp *stp)
{
stp->topology_change_detected = false;
stp->topology_change = false;
}
static void
stp_hold_timer_expiry(struct stp_port *p)
{
if (p->config_pending) {
stp_transmit_config(p);
}
}
static void
stp_initialize_port(struct stp_port *p, enum stp_state state)
{
assert(state & (STP_DISABLED | STP_BLOCKING));
stp_become_designated_port(p);
stp_set_port_state(p, state);
p->topology_change_ack = false;
p->config_pending = false;
p->change_detection_enabled = true;
p->aux = NULL;
stp_stop_timer(&p->message_age_timer);
stp_stop_timer(&p->forward_delay_timer);
stp_stop_timer(&p->hold_timer);
p->tx_count = p->rx_count = p->error_count = 0;
}
static void
stp_become_root_bridge(struct stp *stp)
{
stp->max_age = stp->bridge_max_age;
stp->hello_time = stp->bridge_hello_time;
stp->forward_delay = stp->bridge_forward_delay;
stp_topology_change_detection(stp);
stp_stop_timer(&stp->tcn_timer);
stp_config_bpdu_generation(stp);
stp_start_timer(&stp->hello_timer, 0);
}
static void
stp_start_timer(struct stp_timer *timer, int value)
{
timer->value = value;
timer->active = true;
}
static void
stp_stop_timer(struct stp_timer *timer)
{
timer->active = false;
}
static bool
stp_timer_expired(struct stp_timer *timer, int elapsed, int timeout)
{
if (timer->active) {
timer->value += elapsed;
if (timer->value >= timeout) {
timer->active = false;
return true;
}
}
return false;
}
/* Returns the number of whole STP timer ticks in 'ms' milliseconds. There
* are 256 STP timer ticks per second. */
static int
ms_to_timer(int ms)
{
return ms * 0x100 / 1000;
}
/* Returns the number of whole milliseconds in 'timer' STP timer ticks. There
* are 256 STP timer ticks per second. */
static int
timer_to_ms(int timer)
{
return timer * 1000 / 0x100;
}
static int
clamp(int x, int min, int max)
{
return x < min ? min : x > max ? max : x;
}
static void
stp_update_bridge_timers(struct stp *stp)
{
int ht, ma, fd;
ht = clamp(stp->rq_hello_time, 1000, 10000);
ma = clamp(stp->rq_max_age, MAX(2 * (ht + 1000), 6000), 40000);
fd = clamp(stp->rq_forward_delay, ma / 2 + 1000, 30000);
stp->bridge_hello_time = ms_to_timer(ht);
stp->bridge_max_age = ms_to_timer(ma);
stp->bridge_forward_delay = ms_to_timer(fd);
if (stp_is_root_bridge(stp)) {
stp->max_age = stp->bridge_max_age;
stp->hello_time = stp->bridge_hello_time;
stp->forward_delay = stp->bridge_forward_delay;
}
}
static void
stp_send_bpdu(struct stp_port *p, const void *bpdu, size_t bpdu_size)
{
struct eth_header *eth;
struct llc_header *llc;
struct ofpbuf *pkt;
/* Skeleton. */
pkt = ofpbuf_new(ETH_HEADER_LEN + LLC_HEADER_LEN + bpdu_size);
pkt->l2 = eth = ofpbuf_put_zeros(pkt, sizeof *eth);
llc = ofpbuf_put_zeros(pkt, sizeof *llc);
pkt->l3 = ofpbuf_put(pkt, bpdu, bpdu_size);
/* 802.2 header. */
memcpy(eth->eth_dst, eth_addr_stp, ETH_ADDR_LEN);
/* p->stp->send_bpdu() must fill in source address. */
eth->eth_type = htons(pkt->size - ETH_HEADER_LEN);
/* LLC header. */
llc->llc_dsap = STP_LLC_DSAP;
llc->llc_ssap = STP_LLC_SSAP;
llc->llc_cntl = STP_LLC_CNTL;
p->stp->send_bpdu(pkt, stp_port_no(p), p->stp->aux);
p->tx_count++;
}
/* Unixctl. */
static struct stp *
stp_find(const char *name)
{
struct stp *stp;
LIST_FOR_EACH (stp, node, &all_stps) {
if (!strcmp(stp->name, name)) {
return stp;
}
}
return NULL;
}
static void
stp_unixctl_tcn(struct unixctl_conn *conn, int argc,
const char *argv[], void *aux OVS_UNUSED)
{
if (argc > 1) {
struct stp *stp = stp_find(argv[1]);
if (!stp) {
unixctl_command_reply_error(conn, "no such stp object");
return;
}
stp_topology_change_detection(stp);
} else {
struct stp *stp;
LIST_FOR_EACH (stp, node, &all_stps) {
stp_topology_change_detection(stp);
}
}
unixctl_command_reply(conn, "OK");
}
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