1 files changed, 473 insertions, 0 deletions

diff --git a/net/bridge/br_stp.c b/net/bridge/br_stp.c
new file mode 100644
index 0000000..6e63ec3
--- /dev/null
+++ b/net/bridge/br_stp.c
@@ -0,0 +1,473 @@
+/*
+ *	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.
+ */
+#define MESSAGE_AGE_INCR	((HZ < 256) ? 1 : (HZ/256))
+
+static const char *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)
+{
+	pr_info("%s: port %d(%s) entering %s state\n",
+		p->br->dev->name, 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 = br->max_age
+			- (root->message_age_timer.expires - jiffies)
+			+ 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 inline 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;
+
+	mod_timer(&p->message_age_timer, jiffies
+		  + (p->br->max_age - bpdu->message_age));
+}
+
+/* called under bridge lock */
+static inline 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(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 inline 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);
+
+	pr_info("%s: topology change detected, %s\n", br->dev->name,
+		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 inline 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);
+		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->forward_delay == 0) {
+		p->state = BR_STATE_FORWARDING;
+		br_topology_change_detection(br);
+		del_timer(&p->forward_delay_timer);
+	}
+	else if (p->br->stp_enabled == BR_KERNEL_STP)
+		p->state = BR_STATE_LISTENING;
+	else
+		p->state = BR_STATE_LEARNING;
+
+	br_log_state(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;
+
+	/* Don't change port states if userspace is handling STP */
+	if (br->stp_enabled == BR_USER_STP)
+		return;
+
+	list_for_each_entry(p, &br->port_list, list) {
+		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)) {
+				del_timer(&p->message_age_timer);
+				br_make_forwarding(p);
+			} else {
+				p->config_pending = 0;
+				p->topology_change_ack = 0;
+				br_make_blocking(p);
+			}
+		}
+
+	}
+}
+
+/* called under bridge lock */
+static inline 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, 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)) {
+		pr_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);
+	}
+}