/*
   *	Spanning tree protocol; interface code
   *	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/kmod.h>

  #include <linux/etherdevice.h>

  #include <linux/rtnetlink.h>

  
  #include "br_private.h"
  #include "br_private_stp.h"
  
  
  /* Port id is composed of priority and port number.

   * NB: some bits of priority are dropped to

   *     make room for more ports.
   */
  static inline port_id br_make_port_id(__u8 priority, __u16 port_no)
  {

  	return ((u16)priority << BR_PORT_BITS)

  		| (port_no & ((1<<BR_PORT_BITS)-1));
  }

  #define BR_MAX_PORT_PRIORITY ((u16)~0 >> BR_PORT_BITS)

  /* called under bridge lock */
  void br_init_port(struct net_bridge_port *p)
  {
  	p->port_id = br_make_port_id(p->priority, p->port_no);
  	br_become_designated_port(p);
  	p->state = BR_STATE_BLOCKING;
  	p->topology_change_ack = 0;
  	p->config_pending = 0;

  }
  
  /* called under bridge lock */
  void br_stp_enable_bridge(struct net_bridge *br)
  {
  	struct net_bridge_port *p;
  
  	spin_lock_bh(&br->lock);
  	mod_timer(&br->hello_timer, jiffies + br->hello_time);
  	mod_timer(&br->gc_timer, jiffies + HZ/10);

  	br_config_bpdu_generation(br);
  
  	list_for_each_entry(p, &br->port_list, list) {
  		if ((p->dev->flags & IFF_UP) && netif_carrier_ok(p->dev))
  			br_stp_enable_port(p);
  
  	}
  	spin_unlock_bh(&br->lock);
  }
  
  /* NO locks held */
  void br_stp_disable_bridge(struct net_bridge *br)
  {
  	struct net_bridge_port *p;

  	spin_lock_bh(&br->lock);

  	list_for_each_entry(p, &br->port_list, list) {
  		if (p->state != BR_STATE_DISABLED)
  			br_stp_disable_port(p);
  
  	}
  
  	br->topology_change = 0;
  	br->topology_change_detected = 0;

  	spin_unlock_bh(&br->lock);

  
  	del_timer_sync(&br->hello_timer);
  	del_timer_sync(&br->topology_change_timer);
  	del_timer_sync(&br->tcn_timer);
  	del_timer_sync(&br->gc_timer);
  }
  
  /* called under bridge lock */
  void br_stp_enable_port(struct net_bridge_port *p)
  {
  	br_init_port(p);
  	br_port_state_selection(p->br);

  	br_log_state(p);

  	br_ifinfo_notify(RTM_NEWLINK, p);

  }
  
  /* called under bridge lock */
  void br_stp_disable_port(struct net_bridge_port *p)
  {

  	struct net_bridge *br = p->br;

  	int wasroot;

  	br_log_state(p);

  
  	wasroot = br_is_root_bridge(br);
  	br_become_designated_port(p);
  	p->state = BR_STATE_DISABLED;
  	p->topology_change_ack = 0;
  	p->config_pending = 0;

  	br_ifinfo_notify(RTM_NEWLINK, p);

  	del_timer(&p->message_age_timer);
  	del_timer(&p->forward_delay_timer);
  	del_timer(&p->hold_timer);

  	br_fdb_delete_by_port(br, p, 0);

  	br_multicast_disable_port(p);

  	br_configuration_update(br);
  
  	br_port_state_selection(br);
  
  	if (br_is_root_bridge(br) && !wasroot)
  		br_become_root_bridge(br);
  }

  static void br_stp_start(struct net_bridge *br)
  {
  	int r;
  	char *argv[] = { BR_STP_PROG, br->dev->name, "start", NULL };
  	char *envp[] = { NULL };

  	r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);

  	if (r == 0) {
  		br->stp_enabled = BR_USER_STP;

  		br_debug(br, "userspace STP started
  ");

  	} else {
  		br->stp_enabled = BR_KERNEL_STP;

  		br_debug(br, "using kernel STP
  ");

  
  		/* To start timers on any ports left in blocking */
  		spin_lock_bh(&br->lock);
  		br_port_state_selection(br);
  		spin_unlock_bh(&br->lock);
  	}
  }
  
  static void br_stp_stop(struct net_bridge *br)
  {
  	int r;
  	char *argv[] = { BR_STP_PROG, br->dev->name, "stop", NULL };
  	char *envp[] = { NULL };
  
  	if (br->stp_enabled == BR_USER_STP) {

  		r = call_usermodehelper(BR_STP_PROG, argv, envp, UMH_WAIT_PROC);

  		br_info(br, "userspace STP stopped, return code %d
  ", r);

  
  		/* To start timers on any ports left in blocking */
  		spin_lock_bh(&br->lock);
  		br_port_state_selection(br);
  		spin_unlock_bh(&br->lock);
  	}
  
  	br->stp_enabled = BR_NO_STP;
  }
  
  void br_stp_set_enabled(struct net_bridge *br, unsigned long val)
  {
  	ASSERT_RTNL();
  
  	if (val) {
  		if (br->stp_enabled == BR_NO_STP)
  			br_stp_start(br);
  	} else {
  		if (br->stp_enabled != BR_NO_STP)
  			br_stp_stop(br);
  	}
  }

  /* called under bridge lock */

  void br_stp_change_bridge_id(struct net_bridge *br, const unsigned char *addr)

  {

  	/* should be aligned on 2 bytes for compare_ether_addr() */
  	unsigned short oldaddr_aligned[ETH_ALEN >> 1];
  	unsigned char *oldaddr = (unsigned char *)oldaddr_aligned;

  	struct net_bridge_port *p;
  	int wasroot;
  
  	wasroot = br_is_root_bridge(br);
  
  	memcpy(oldaddr, br->bridge_id.addr, ETH_ALEN);
  	memcpy(br->bridge_id.addr, addr, ETH_ALEN);
  	memcpy(br->dev->dev_addr, addr, ETH_ALEN);
  
  	list_for_each_entry(p, &br->port_list, list) {

  		if (!compare_ether_addr(p->designated_bridge.addr, oldaddr))

  			memcpy(p->designated_bridge.addr, addr, ETH_ALEN);

  		if (!compare_ether_addr(p->designated_root.addr, oldaddr))

  			memcpy(p->designated_root.addr, addr, ETH_ALEN);
  
  	}
  
  	br_configuration_update(br);
  	br_port_state_selection(br);
  	if (br_is_root_bridge(br) && !wasroot)
  		br_become_root_bridge(br);
  }

  /* should be aligned on 2 bytes for compare_ether_addr() */
  static const unsigned short br_mac_zero_aligned[ETH_ALEN >> 1];

  
  /* called under bridge lock */

  bool br_stp_recalculate_bridge_id(struct net_bridge *br)

  {

  	const unsigned char *br_mac_zero =
  			(const unsigned char *)br_mac_zero_aligned;

  	const unsigned char *addr = br_mac_zero;
  	struct net_bridge_port *p;

  	/* user has chosen a value so keep it */
  	if (br->flags & BR_SET_MAC_ADDR)

  		return false;

  	list_for_each_entry(p, &br->port_list, list) {
  		if (addr == br_mac_zero ||

  		    memcmp(p->dev->dev_addr, addr, ETH_ALEN) < 0)

  			addr = p->dev->dev_addr;
  
  	}

  	if (compare_ether_addr(br->bridge_id.addr, addr) == 0)
  		return false;	/* no change */
  
  	br_stp_change_bridge_id(br, addr);
  	return true;

  }
  
  /* called under bridge lock */
  void br_stp_set_bridge_priority(struct net_bridge *br, u16 newprio)
  {
  	struct net_bridge_port *p;
  	int wasroot;
  
  	wasroot = br_is_root_bridge(br);
  
  	list_for_each_entry(p, &br->port_list, list) {
  		if (p->state != BR_STATE_DISABLED &&
  		    br_is_designated_port(p)) {
  			p->designated_bridge.prio[0] = (newprio >> 8) & 0xFF;
  			p->designated_bridge.prio[1] = newprio & 0xFF;
  		}
  
  	}
  
  	br->bridge_id.prio[0] = (newprio >> 8) & 0xFF;
  	br->bridge_id.prio[1] = newprio & 0xFF;
  	br_configuration_update(br);
  	br_port_state_selection(br);
  	if (br_is_root_bridge(br) && !wasroot)
  		br_become_root_bridge(br);
  }
  
  /* called under bridge lock */

  int br_stp_set_port_priority(struct net_bridge_port *p, unsigned long newprio)

  {

  	port_id new_port_id;
  
  	if (newprio > BR_MAX_PORT_PRIORITY)
  		return -ERANGE;

  	new_port_id = br_make_port_id(newprio, p->port_no);

  	if (br_is_designated_port(p))
  		p->designated_port = new_port_id;
  
  	p->port_id = new_port_id;
  	p->priority = newprio;
  	if (!memcmp(&p->br->bridge_id, &p->designated_bridge, 8) &&
  	    p->port_id < p->designated_port) {
  		br_become_designated_port(p);
  		br_port_state_selection(p->br);
  	}

  
  	return 0;

  }
  
  /* called under bridge lock */

  int br_stp_set_path_cost(struct net_bridge_port *p, unsigned long path_cost)

  {

  	if (path_cost < BR_MIN_PATH_COST ||
  	    path_cost > BR_MAX_PATH_COST)
  		return -ERANGE;

  	p->path_cost = path_cost;
  	br_configuration_update(p->br);
  	br_port_state_selection(p->br);

  	return 0;

  }
  
  ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id)
  {
  	return sprintf(buf, "%.2x%.2x.%.2x%.2x%.2x%.2x%.2x%.2x
  ",
  	       id->prio[0], id->prio[1],
  	       id->addr[0], id->addr[1], id->addr[2],
  	       id->addr[3], id->addr[4], id->addr[5]);
  }