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Diffstat (limited to 'lib/stp.c')
| -rw-r--r-- | lib/stp.c | 1226 |
1 files changed, 1226 insertions, 0 deletions
diff --git a/lib/stp.c b/lib/stp.c new file mode 100644 index 000000000..59f5c6158 --- /dev/null +++ b/lib/stp.c @@ -0,0 +1,1226 @@ +/* + * Copyright (c) 2008, 2009 Nicira Networks. + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +/* Based on sample implementation in 802.1D-1998. Above copyright and license + * applies to all modifications. */ + +#include "stp.h" +#include <arpa/inet.h> +#include <assert.h> +#include <inttypes.h> +#include <stdlib.h> +#include "ofpbuf.h" +#include "packets.h" +#include "util.h" +#include "xtoxll.h" + +#include "vlog.h" +#define THIS_MODULE VLM_stp + +/* Ethernet address used as the destination for STP frames. */ +const uint8_t stp_eth_addr[ETH_ADDR_LEN] += { 0x01, 0x80, 0xC2, 0x00, 0x00, 0x01 }; + +#define STP_PROTOCOL_ID 0x0000 +#define STP_PROTOCOL_VERSION 0x00 +#define STP_TYPE_CONFIG 0x00 +#define STP_TYPE_TCN 0x80 + +struct stp_bpdu_header { + uint16_t 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. */ + uint64_t root_id; /* 8.5.1.1: Bridge believed to be root. */ + uint32_t root_path_cost; /* 8.5.1.2: Cost of path to root. */ + uint64_t bridge_id; /* 8.5.1.3: ID of transmitting bridge. */ + uint16_t port_id; /* 8.5.1.4: Port transmitting the BPDU. */ + uint16_t message_age; /* 8.5.1.5: Age of BPDU at tx time. */ + uint16_t max_age; /* 8.5.1.6: Timeout for received data. */ + uint16_t hello_time; /* 8.5.1.7: Time between BPDU generation. */ + uint16_t 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; + 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. */ + + bool state_changed; +}; + +struct stp { + /* 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. */ + struct stp_port *first_changed_port; + void (*send_bpdu)(struct ofpbuf *bpdu, int port_no, void *aux); + void *aux; +}; + +#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 ms_to_timer_remainder(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); + +/* 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 + */ +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 = xcalloc(1, 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 = 6000; + stp->rq_hello_time = 2000; + stp->rq_forward_delay = 4000; + 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); + } + return stp; +} + +/* Destroys 'stp'. */ +void +stp_destroy(struct stp *stp) +{ + 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_to_timer_remainder(ms); + 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 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; +} + +/* 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); + 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)); + 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); + 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); + return; + } + stp_received_tcn_bpdu(stp, p); + break; + + default: + VLOG_WARN("%s: received BPDU of unexpected type %"PRIu8, + stp->name, header->bpdu_type); + return; + } +} + +/* Returns the STP entity in which 'p' is nested. */ +struct stp * +stp_port_get_stp(struct stp_port *p) +{ + return p->stp; +} + +/* 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 state of port 'p'. */ +enum stp_state +stp_port_get_state(const struct stp_port *p) +{ + return p->state; +} + +/* 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); + } + } +} + +/* 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); + } + } +} + +/* 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, (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). */ +} + +/* 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 |= htons(STP_CONFIG_TOPOLOGY_CHANGE_ACK); + } + if (stp->topology_change) { + config.flags |= htons(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 & htons(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) +{ + 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->topology_change_detected = true; +} + +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); +} + +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 & htons(STP_CONFIG_TOPOLOGY_CHANGE_ACK)) { + stp_topology_change_acknowledged(stp); + } + } + } else if (stp_is_designated_port(p)) { + stp_transmit_config(p); + } + } +} + +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; + stp_stop_timer(&p->message_age_timer); + stp_stop_timer(&p->forward_delay_timer); + stp_stop_timer(&p->hold_timer); +} + +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 leftover milliseconds when 'ms' is converted to STP + * timer ticks. */ +static int +ms_to_timer_remainder(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, stp_eth_addr, 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); +} |