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/*
* Spanning tree protocol; generic parts
* Linux ethernet bridge
*
* Authors:
* Lennert Buytenhek <buytenh@gnu.org>
*
* $Id: br_stp.c,v 1.4 2000/06/19 10:13:35 davem Exp $
*
* 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/if_bridge.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
#include "br_private.h"
#include "br_private_stp.h"
/* called under ioctl_lock or bridge lock */
int br_is_root_bridge(struct net_bridge *br)
{
return !memcmp(&br->bridge_id, &br->designated_root, 8);
}
/* called under bridge lock */
int br_is_designated_port(struct net_bridge_port *p)
{
return !memcmp(&p->designated_bridge, &p->br->bridge_id, 8) &&
(p->designated_port == p->port_id);
}
/* called under ioctl_lock or bridge lock */
struct net_bridge_port *br_get_port(struct net_bridge *br, int port_no)
{
struct net_bridge_port *p;
p = br->port_list;
while (p != NULL) {
if (p->port_no == port_no)
return p;
p = p->next;
}
return NULL;
}
/* called under bridge lock */
static int br_should_become_root_port(struct net_bridge_port *p, int 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;
int root_port;
root_port = 0;
p = br->port_list;
while (p != NULL) {
if (br_should_become_root_port(p, root_port))
root_port = p->port_no;
p = p->next;
}
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);
br_timer_clear(&br->tcn_timer);
br_config_bpdu_generation(br);
br_timer_set(&br->hello_timer, jiffies);
}
/* called under bridge lock */
void br_transmit_config(struct net_bridge_port *p)
{
struct br_config_bpdu bpdu;
struct net_bridge *br;
if (br_timer_is_running(&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;
bpdu.message_age = 0;
if (!br_is_root_bridge(br)) {
struct net_bridge_port *root;
unsigned long age;
root = br_get_port(br, br->root_port);
age = br_timer_get_residue(&root->message_age_timer) + 1;
bpdu.message_age = age;
}
bpdu.max_age = br->max_age;
bpdu.hello_time = br->hello_time;
bpdu.forward_delay = br->forward_delay;
br_send_config_bpdu(p, &bpdu);
p->topology_change_ack = 0;
p->config_pending = 0;
br_timer_set(&p->hold_timer, jiffies);
}
/* called under bridge lock */
static void br_record_config_information(struct net_bridge_port *p, 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;
br_timer_set(&p->message_age_timer, jiffies - bpdu->message_age);
}
/* called under bridge lock */
static void br_record_config_timeout_values(struct net_bridge *br, 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(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;
p = br->port_list;
while (p != NULL) {
if (p->state != BR_STATE_DISABLED &&
br_should_become_designated_port(p))
br_become_designated_port(p);
p = p->next;
}
}
/* called under bridge lock */
static int br_supersedes_port_info(struct net_bridge_port *p, 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;
br_timer_clear(&br->tcn_timer);
}
/* called under bridge lock */
void br_topology_change_detection(struct net_bridge *br)
{
printk(KERN_INFO "%s: topology change detected", br->dev.name);
if (br_is_root_bridge(br)) {
printk(", propagating");
br->topology_change = 1;
br_timer_set(&br->topology_change_timer, jiffies);
} else if (!br->topology_change_detected) {
printk(", sending tcn bpdu");
br_transmit_tcn(br);
br_timer_set(&br->tcn_timer, jiffies);
}
printk("\n");
br->topology_change_detected = 1;
}
/* called under bridge lock */
void br_config_bpdu_generation(struct net_bridge *br)
{
struct net_bridge_port *p;
p = br->port_list;
while (p != NULL) {
if (p->state != BR_STATE_DISABLED &&
br_is_designated_port(p))
br_transmit_config(p);
p = p->next;
}
}
/* 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);
printk(KERN_INFO "%s: port %i(%s) entering %s state\n",
p->br->dev.name, p->port_no, p->dev->name, "blocking");
p->state = BR_STATE_BLOCKING;
br_timer_clear(&p->forward_delay_timer);
}
}
/* called under bridge lock */
static void br_make_forwarding(struct net_bridge_port *p)
{
if (p->state == BR_STATE_BLOCKING) {
printk(KERN_INFO "%s: port %i(%s) entering %s state\n",
p->br->dev.name, p->port_no, p->dev->name, "listening");
p->state = BR_STATE_LISTENING;
br_timer_set(&p->forward_delay_timer, jiffies);
}
}
/* called under bridge lock */
void br_port_state_selection(struct net_bridge *br)
{
struct net_bridge_port *p;
p = br->port_list;
while (p != NULL) {
if (p->state != BR_STATE_DISABLED) {
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)) {
br_timer_clear(&p->message_age_timer);
br_make_forwarding(p);
} else {
p->config_pending = 0;
p->topology_change_ack = 0;
br_make_blocking(p);
}
}
p = p->next;
}
}
/* called under bridge lock */
static void br_topology_change_acknowledge(struct net_bridge_port *p)
{
p->topology_change_ack = 1;
br_transmit_config(p);
}
/* lock-safe */
void br_received_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
{
struct net_bridge *br;
int was_root;
if (p->state == BR_STATE_DISABLED)
return;
br = p->br;
read_lock(&br->lock);
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) {
br_timer_clear(&br->hello_timer);
if (br->topology_change_detected) {
br_timer_clear(&br->topology_change_timer);
br_transmit_tcn(br);
br_timer_set(&br->tcn_timer, jiffies);
}
}
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);
}
read_unlock(&br->lock);
}
/* lock-safe */
void br_received_tcn_bpdu(struct net_bridge_port *p)
{
read_lock(&p->br->lock);
if (p->state != BR_STATE_DISABLED &&
br_is_designated_port(p)) {
printk(KERN_INFO "%s: received tcn bpdu on port %i(%s)\n",
p->br->dev.name, p->port_no, p->dev->name);
br_topology_change_detection(p->br);
br_topology_change_acknowledge(p);
}
read_unlock(&p->br->lock);
}
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