diff options
Diffstat (limited to 'net/bridge/br_stp.c')
| -rw-r--r-- | net/bridge/br_stp.c | 534 |
1 files changed, 534 insertions, 0 deletions
diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c new file mode 100644 index 00000000..8c836d96 --- /dev/null +++ b/net/bridge/br_stp.c @@ -0,0 +1,534 @@ +/* + * Spanning tree protocol; generic parts + * Linux ethernet bridge + * + * Authors: + * Lennert Buytenhek <buytenh@gnu.org> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +#include <linux/kernel.h> +#include <linux/rculist.h> + +#include "br_private.h" +#include "br_private_stp.h" + +/* since time values in bpdu are in jiffies and then scaled (1/256) + * before sending, make sure that is at least one STP tick. + */ +#define MESSAGE_AGE_INCR ((HZ / 256) + 1) + +static const char *const br_port_state_names[] = { + [BR_STATE_DISABLED] = "disabled", + [BR_STATE_LISTENING] = "listening", + [BR_STATE_LEARNING] = "learning", + [BR_STATE_FORWARDING] = "forwarding", + [BR_STATE_BLOCKING] = "blocking", +}; + +void br_log_state(const struct net_bridge_port *p) +{ + br_info(p->br, "port %u(%s) entered %s state\n", + (unsigned) p->port_no, p->dev->name, + br_port_state_names[p->state]); +} + +/* called under bridge lock */ +struct net_bridge_port *br_get_port(struct net_bridge *br, u16 port_no) +{ + struct net_bridge_port *p; + + list_for_each_entry_rcu(p, &br->port_list, list) { + if (p->port_no == port_no) + return p; + } + + return NULL; +} + +/* called under bridge lock */ +static int br_should_become_root_port(const struct net_bridge_port *p, + u16 root_port) +{ + struct net_bridge *br; + struct net_bridge_port *rp; + int t; + + br = p->br; + if (p->state == BR_STATE_DISABLED || + br_is_designated_port(p)) + return 0; + + if (memcmp(&br->bridge_id, &p->designated_root, 8) <= 0) + return 0; + + if (!root_port) + return 1; + + rp = br_get_port(br, root_port); + + t = memcmp(&p->designated_root, &rp->designated_root, 8); + if (t < 0) + return 1; + else if (t > 0) + return 0; + + if (p->designated_cost + p->path_cost < + rp->designated_cost + rp->path_cost) + return 1; + else if (p->designated_cost + p->path_cost > + rp->designated_cost + rp->path_cost) + return 0; + + t = memcmp(&p->designated_bridge, &rp->designated_bridge, 8); + if (t < 0) + return 1; + else if (t > 0) + return 0; + + if (p->designated_port < rp->designated_port) + return 1; + else if (p->designated_port > rp->designated_port) + return 0; + + if (p->port_id < rp->port_id) + return 1; + + return 0; +} + +/* called under bridge lock */ +static void br_root_selection(struct net_bridge *br) +{ + struct net_bridge_port *p; + u16 root_port = 0; + + list_for_each_entry(p, &br->port_list, list) { + if (br_should_become_root_port(p, root_port)) + root_port = p->port_no; + } + + br->root_port = root_port; + + if (!root_port) { + br->designated_root = br->bridge_id; + br->root_path_cost = 0; + } else { + p = br_get_port(br, root_port); + br->designated_root = p->designated_root; + br->root_path_cost = p->designated_cost + p->path_cost; + } +} + +/* called under bridge lock */ +void br_become_root_bridge(struct net_bridge *br) +{ + br->max_age = br->bridge_max_age; + br->hello_time = br->bridge_hello_time; + br->forward_delay = br->bridge_forward_delay; + br_topology_change_detection(br); + del_timer(&br->tcn_timer); + + if (br->dev->flags & IFF_UP) { + br_config_bpdu_generation(br); + mod_timer(&br->hello_timer, jiffies + br->hello_time); + } +} + +/* called under bridge lock */ +void br_transmit_config(struct net_bridge_port *p) +{ + struct br_config_bpdu bpdu; + struct net_bridge *br; + + if (timer_pending(&p->hold_timer)) { + p->config_pending = 1; + return; + } + + br = p->br; + + bpdu.topology_change = br->topology_change; + bpdu.topology_change_ack = p->topology_change_ack; + bpdu.root = br->designated_root; + bpdu.root_path_cost = br->root_path_cost; + bpdu.bridge_id = br->bridge_id; + bpdu.port_id = p->port_id; + if (br_is_root_bridge(br)) + bpdu.message_age = 0; + else { + struct net_bridge_port *root + = br_get_port(br, br->root_port); + bpdu.message_age = (jiffies - root->designated_age) + + MESSAGE_AGE_INCR; + } + bpdu.max_age = br->max_age; + bpdu.hello_time = br->hello_time; + bpdu.forward_delay = br->forward_delay; + + if (bpdu.message_age < br->max_age) { + br_send_config_bpdu(p, &bpdu); + p->topology_change_ack = 0; + p->config_pending = 0; + mod_timer(&p->hold_timer, + round_jiffies(jiffies + BR_HOLD_TIME)); + } +} + +/* called under bridge lock */ +static void br_record_config_information(struct net_bridge_port *p, + const struct br_config_bpdu *bpdu) +{ + p->designated_root = bpdu->root; + p->designated_cost = bpdu->root_path_cost; + p->designated_bridge = bpdu->bridge_id; + p->designated_port = bpdu->port_id; + p->designated_age = jiffies - bpdu->message_age; + + mod_timer(&p->message_age_timer, jiffies + + (p->br->max_age - bpdu->message_age)); +} + +/* called under bridge lock */ +static void br_record_config_timeout_values(struct net_bridge *br, + const struct br_config_bpdu *bpdu) +{ + br->max_age = bpdu->max_age; + br->hello_time = bpdu->hello_time; + br->forward_delay = bpdu->forward_delay; + br->topology_change = bpdu->topology_change; +} + +/* called under bridge lock */ +void br_transmit_tcn(struct net_bridge *br) +{ + br_send_tcn_bpdu(br_get_port(br, br->root_port)); +} + +/* called under bridge lock */ +static int br_should_become_designated_port(const struct net_bridge_port *p) +{ + struct net_bridge *br; + int t; + + br = p->br; + if (br_is_designated_port(p)) + return 1; + + if (memcmp(&p->designated_root, &br->designated_root, 8)) + return 1; + + if (br->root_path_cost < p->designated_cost) + return 1; + else if (br->root_path_cost > p->designated_cost) + return 0; + + t = memcmp(&br->bridge_id, &p->designated_bridge, 8); + if (t < 0) + return 1; + else if (t > 0) + return 0; + + if (p->port_id < p->designated_port) + return 1; + + return 0; +} + +/* called under bridge lock */ +static void br_designated_port_selection(struct net_bridge *br) +{ + struct net_bridge_port *p; + + list_for_each_entry(p, &br->port_list, list) { + if (p->state != BR_STATE_DISABLED && + br_should_become_designated_port(p)) + br_become_designated_port(p); + + } +} + +/* called under bridge lock */ +static int br_supersedes_port_info(const struct net_bridge_port *p, + const struct br_config_bpdu *bpdu) +{ + int t; + + t = memcmp(&bpdu->root, &p->designated_root, 8); + if (t < 0) + return 1; + else if (t > 0) + return 0; + + if (bpdu->root_path_cost < p->designated_cost) + return 1; + else if (bpdu->root_path_cost > p->designated_cost) + return 0; + + t = memcmp(&bpdu->bridge_id, &p->designated_bridge, 8); + if (t < 0) + return 1; + else if (t > 0) + return 0; + + if (memcmp(&bpdu->bridge_id, &p->br->bridge_id, 8)) + return 1; + + if (bpdu->port_id <= p->designated_port) + return 1; + + return 0; +} + +/* called under bridge lock */ +static void br_topology_change_acknowledged(struct net_bridge *br) +{ + br->topology_change_detected = 0; + del_timer(&br->tcn_timer); +} + +/* called under bridge lock */ +void br_topology_change_detection(struct net_bridge *br) +{ + int isroot = br_is_root_bridge(br); + + if (br->stp_enabled != BR_KERNEL_STP) + return; + + br_info(br, "topology change detected, %s\n", + isroot ? "propagating" : "sending tcn bpdu"); + + if (isroot) { + br->topology_change = 1; + mod_timer(&br->topology_change_timer, jiffies + + br->bridge_forward_delay + br->bridge_max_age); + } else if (!br->topology_change_detected) { + br_transmit_tcn(br); + mod_timer(&br->tcn_timer, jiffies + br->bridge_hello_time); + } + + br->topology_change_detected = 1; +} + +/* called under bridge lock */ +void br_config_bpdu_generation(struct net_bridge *br) +{ + struct net_bridge_port *p; + + list_for_each_entry(p, &br->port_list, list) { + if (p->state != BR_STATE_DISABLED && + br_is_designated_port(p)) + br_transmit_config(p); + } +} + +/* called under bridge lock */ +static void br_reply(struct net_bridge_port *p) +{ + br_transmit_config(p); +} + +/* called under bridge lock */ +void br_configuration_update(struct net_bridge *br) +{ + br_root_selection(br); + br_designated_port_selection(br); +} + +/* called under bridge lock */ +void br_become_designated_port(struct net_bridge_port *p) +{ + struct net_bridge *br; + + br = p->br; + p->designated_root = br->designated_root; + p->designated_cost = br->root_path_cost; + p->designated_bridge = br->bridge_id; + p->designated_port = p->port_id; +} + + +/* called under bridge lock */ +static void br_make_blocking(struct net_bridge_port *p) +{ + if (p->state != BR_STATE_DISABLED && + p->state != BR_STATE_BLOCKING) { + if (p->state == BR_STATE_FORWARDING || + p->state == BR_STATE_LEARNING) + br_topology_change_detection(p->br); + + p->state = BR_STATE_BLOCKING; + br_log_state(p); + br_ifinfo_notify(RTM_NEWLINK, p); + + del_timer(&p->forward_delay_timer); + } +} + +/* called under bridge lock */ +static void br_make_forwarding(struct net_bridge_port *p) +{ + struct net_bridge *br = p->br; + + if (p->state != BR_STATE_BLOCKING) + return; + + if (br->stp_enabled == BR_NO_STP || br->forward_delay == 0) { + p->state = BR_STATE_FORWARDING; + br_topology_change_detection(br); + del_timer(&p->forward_delay_timer); + } else if (br->stp_enabled == BR_KERNEL_STP) + p->state = BR_STATE_LISTENING; + else + p->state = BR_STATE_LEARNING; + + br_multicast_enable_port(p); + br_log_state(p); + br_ifinfo_notify(RTM_NEWLINK, p); + + if (br->forward_delay != 0) + mod_timer(&p->forward_delay_timer, jiffies + br->forward_delay); +} + +/* called under bridge lock */ +void br_port_state_selection(struct net_bridge *br) +{ + struct net_bridge_port *p; + unsigned int liveports = 0; + + list_for_each_entry(p, &br->port_list, list) { + if (p->state == BR_STATE_DISABLED) + continue; + + /* Don't change port states if userspace is handling STP */ + if (br->stp_enabled != BR_USER_STP) { + if (p->port_no == br->root_port) { + p->config_pending = 0; + p->topology_change_ack = 0; + br_make_forwarding(p); + } else if (br_is_designated_port(p)) { + del_timer(&p->message_age_timer); + br_make_forwarding(p); + } else { + p->config_pending = 0; + p->topology_change_ack = 0; + br_make_blocking(p); + } + } + + if (p->state == BR_STATE_FORWARDING) + ++liveports; + } + + if (liveports == 0) + netif_carrier_off(br->dev); + else + netif_carrier_on(br->dev); +} + +/* called under bridge lock */ +static void br_topology_change_acknowledge(struct net_bridge_port *p) +{ + p->topology_change_ack = 1; + br_transmit_config(p); +} + +/* called under bridge lock */ +void br_received_config_bpdu(struct net_bridge_port *p, + const struct br_config_bpdu *bpdu) +{ + struct net_bridge *br; + int was_root; + + br = p->br; + was_root = br_is_root_bridge(br); + + if (br_supersedes_port_info(p, bpdu)) { + br_record_config_information(p, bpdu); + br_configuration_update(br); + br_port_state_selection(br); + + if (!br_is_root_bridge(br) && was_root) { + del_timer(&br->hello_timer); + if (br->topology_change_detected) { + del_timer(&br->topology_change_timer); + br_transmit_tcn(br); + + mod_timer(&br->tcn_timer, + jiffies + br->bridge_hello_time); + } + } + + if (p->port_no == br->root_port) { + br_record_config_timeout_values(br, bpdu); + br_config_bpdu_generation(br); + if (bpdu->topology_change_ack) + br_topology_change_acknowledged(br); + } + } else if (br_is_designated_port(p)) { + br_reply(p); + } +} + +/* called under bridge lock */ +void br_received_tcn_bpdu(struct net_bridge_port *p) +{ + if (br_is_designated_port(p)) { + br_info(p->br, "port %u(%s) received tcn bpdu\n", + (unsigned) p->port_no, p->dev->name); + + br_topology_change_detection(p->br); + br_topology_change_acknowledge(p); + } +} + +/* Change bridge STP parameter */ +int br_set_hello_time(struct net_bridge *br, unsigned long val) +{ + unsigned long t = clock_t_to_jiffies(val); + + if (t < BR_MIN_HELLO_TIME || t > BR_MAX_HELLO_TIME) + return -ERANGE; + + spin_lock_bh(&br->lock); + br->bridge_hello_time = t; + if (br_is_root_bridge(br)) + br->hello_time = br->bridge_hello_time; + spin_unlock_bh(&br->lock); + return 0; +} + +int br_set_max_age(struct net_bridge *br, unsigned long val) +{ + unsigned long t = clock_t_to_jiffies(val); + + if (t < BR_MIN_MAX_AGE || t > BR_MAX_MAX_AGE) + return -ERANGE; + + spin_lock_bh(&br->lock); + br->bridge_max_age = t; + if (br_is_root_bridge(br)) + br->max_age = br->bridge_max_age; + spin_unlock_bh(&br->lock); + return 0; + +} + +int br_set_forward_delay(struct net_bridge *br, unsigned long val) +{ + unsigned long t = clock_t_to_jiffies(val); + + if (br->stp_enabled != BR_NO_STP && + (t < BR_MIN_FORWARD_DELAY || t > BR_MAX_FORWARD_DELAY)) + return -ERANGE; + + spin_lock_bh(&br->lock); + br->bridge_forward_delay = t; + if (br_is_root_bridge(br)) + br->forward_delay = br->bridge_forward_delay; + spin_unlock_bh(&br->lock); + return 0; +} |