/*
 * IS-IS Rout(e)ing protocol - isis_dr.c
 *                             IS-IS designated router related routines   
 *
 * Copyright (C) 2001,2002   Sampo Saaristo
 *                           Tampere University of Technology      
 *                           Institute of Communications Engineering
 *
 * This program is free software; you can redistribute it and/or modify it 
 * under the terms of the GNU General Public Licenseas published by the Free 
 * Software Foundation; either version 2 of the License, or (at your option) 
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,but WITHOUT 
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for 
 * more details.

 * You should have received a copy of the GNU General Public License along 
 * with this program; if not, write to the Free Software Foundation, Inc., 
 * 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */


#include <zebra.h>
#include <net/ethernet.h>

#include "log.h"
#include "hash.h"
#include "thread.h"
#include "linklist.h"
#include "vty.h"
#include "stream.h"
#include "if.h"

#include "isisd/dict.h"
#include "isisd/isis_constants.h"
#include "isisd/isis_common.h"
#include "isisd/isis_misc.h"
#include "isisd/isis_flags.h"
#include "isisd/isis_circuit.h"
#include "isisd/isisd.h"
#include "isisd/isis_adjacency.h"
#include "isisd/isis_constants.h"
#include "isisd/isis_pdu.h"
#include "isisd/isis_tlv.h"
#include "isisd/isis_lsp.h"
#include "isisd/isis_dr.h"
#include "isisd/isis_events.h"

extern struct isis *isis;
extern struct thread_master *master;

char *
isis_disflag2string (int disflag) {

  switch (disflag) {
    case ISIS_IS_NOT_DIS:
      return "is not DIS";
    case ISIS_IS_DIS:
      return "is DIS";
    case ISIS_WAS_DIS:
      return "was DIS";
  default:
    return "unknown DIS state";
  }
  return NULL; /* not reached */
}


int
isis_run_dr_l1 (struct thread *thread)
{
  struct isis_circuit *circuit;
  
  circuit = THREAD_ARG (thread);
  assert (circuit);

  if (circuit->u.bc.run_dr_elect[0])
    zlog_warn ("isis_run_dr(): run_dr_elect already set for l1");
  
  circuit->u.bc.run_dr_elect[0] = 1;
    
  return ISIS_OK;
}

int
isis_run_dr_l2 (struct thread *thread)
{
  struct isis_circuit *circuit;
  
  circuit = THREAD_ARG (thread);
  assert (circuit);

  if (circuit->u.bc.run_dr_elect[1])
    zlog_warn ("isis_run_dr(): run_dr_elect already set for l2");
  
  
  circuit->u.bc.run_dr_elect[1] = 1;
    
  return ISIS_OK;
}

int
isis_check_dr_change (struct isis_adjacency *adj, int level)
{
  int i;

  if ( adj->dis_record[level-1].dis != 
       adj->dis_record[(1*ISIS_LEVELS) + level - 1].dis) 
    /* was there a DIS state transition ? */ 
    {
      adj->dischanges[level-1]++;
      /* ok rotate the history list through */
      for (i = DIS_RECORDS - 1; i > 0; i--) 
	{
	  adj->dis_record[(i * ISIS_LEVELS) + level - 1].dis = 
            adj->dis_record[((i-1) * ISIS_LEVELS) + level - 1].dis;
	  adj->dis_record[(i * ISIS_LEVELS) + level - 1].last_dis_change = 
            adj->dis_record[((i-1) * ISIS_LEVELS) + level - 1].last_dis_change;
	}
    }
  return ISIS_OK;
}

int 
isis_dr_elect (struct isis_circuit *circuit, int level)
{
  struct list *adjdb;
  struct listnode *node;
  struct isis_adjacency *adj, *adj_dr = NULL;
  struct list *list = list_new ();
  u_char own_prio;
  int biggest_prio = -1;
  int cmp_res, retval = ISIS_OK;
  
  own_prio = circuit->u.bc.priority[level - 1];
  adjdb = circuit->u.bc.adjdb[level - 1];

  if (!adjdb) {
    zlog_warn ("isis_dr_elect() adjdb == NULL");
    retval = ISIS_WARNING;
    list_delete (list);
    goto out;
  }
  isis_adj_build_up_list (adjdb, list);

  /*
   * Loop the adjacencies and find the one with the biggest priority
   */
  for (node = listhead (list); node; nextnode (node)) {
    adj = getdata (node);
    /* clear flag for show output */
    adj->dis_record[level-1].dis = ISIS_IS_NOT_DIS;  
    adj->dis_record[level-1].last_dis_change = time (NULL);

    if (adj->prio[level-1] > biggest_prio) {
      biggest_prio = adj->prio[level-1];
      adj_dr = adj;
    } else if (adj->prio[level-1] == biggest_prio) {
      /*
       * Comparison of MACs breaks a tie
       */
      if (adj_dr) {
        cmp_res = memcmp (adj_dr->snpa, adj->snpa, ETH_ALEN);
        if (cmp_res < 0) {
          adj_dr = adj;
	}
        if (cmp_res == 0)
          zlog_warn ("isis_dr_elect(): multiple adjacencies with same SNPA"); 
      } else {
        adj_dr = adj;
      }
    }
  }
  
  if (!adj_dr) {
    /*
     * Could not find the DR - means we are alone and thus the DR
     */
    if ( !circuit->u.bc.is_dr[level - 1]) {
      list_delete (list);
      list = NULL;
      return isis_dr_commence (circuit, level);
    }
    goto out;
  }

  /*
   * Now we have the DR adjacency, compare it to self
   */
  if (adj_dr->prio[level-1] < own_prio || (adj_dr->prio[level-1] == own_prio &&
                                  memcmp (adj_dr->snpa, circuit->u.bc.snpa, 
                                          ETH_ALEN) < 0)) {
    if (!circuit->u.bc.is_dr[level - 1]) {
      /*
       * We are the DR -> commence
       */
      list_delete (list);
      return isis_dr_commence (circuit, level);
    }
  } else {

    /* ok we have found the DIS - lets mark the adjacency */
    /* set flag for show output */
    adj_dr->dis_record[level - 1].dis = ISIS_IS_DIS; 
    adj_dr->dis_record[level - 1].last_dis_change = time(NULL);

    /* now loop through a second time to check if there has been a DIS change
     * if yes rotate the history log
     */

    for (node = listhead (list); node; nextnode (node)) {
      adj = getdata (node);
      isis_check_dr_change(adj, level);
    }

    /*
     * We are not DR - if we were -> resign
     */

    if (circuit->u.bc.is_dr[level - 1]) {
      list_delete (list);
      return isis_dr_resign (circuit, level);
    }
  }
 out:
  if (list)
    list_delete (list);
  return retval;
}

int 
isis_dr_resign (struct isis_circuit *circuit, int level)
{
  u_char id[ISIS_SYS_ID_LEN + 2];
      
  zlog_info ("isis_dr_resign l%d", level);

  circuit->u.bc.is_dr[level - 1] = 0;
  circuit->u.bc.run_dr_elect[level - 1] = 0; 
  if (circuit->u.bc.t_run_dr[level - 1]) {
    thread_cancel (circuit->u.bc.t_run_dr[level - 1]);
    circuit->u.bc.t_run_dr[level - 1] = NULL;
  }
  if (circuit->u.bc.t_refresh_pseudo_lsp[level - 1]) {
    thread_cancel (circuit->u.bc.t_refresh_pseudo_lsp[level - 1]);
    circuit->u.bc.t_refresh_pseudo_lsp[level - 1] = NULL;
  }
  
  memcpy (id, isis->sysid, ISIS_SYS_ID_LEN);
  LSP_PSEUDO_ID(id) = circuit->circuit_id;
  LSP_FRAGMENT(id) = 0;
  lsp_purge_dr (id, circuit, level);

  if (level == 1) {
    memset (circuit->u.bc.l1_desig_is, 0, ISIS_SYS_ID_LEN + 1);
    
    if (circuit->t_send_csnp[0])
      thread_cancel (circuit->t_send_csnp[0]);    
    
    circuit->u.bc.t_run_dr[0] =
      thread_add_timer (master, isis_run_dr_l1, circuit,
                        2 * circuit->hello_interval[1]);    

    circuit->t_send_psnp[0] = 
      thread_add_timer (master,
                        send_l1_psnp,
                        circuit,
                        isis_jitter (circuit->psnp_interval[level - 1],
                                     PSNP_JITTER));
  } else {
    memset (circuit->u.bc.l2_desig_is, 0, ISIS_SYS_ID_LEN + 1);

    if (circuit->t_send_csnp[0])
      thread_cancel (circuit->t_send_csnp[0]);

    circuit->u.bc.t_run_dr[1] =
      thread_add_timer (master, isis_run_dr_l2, circuit,
                        2 * circuit->hello_interval[1]);    
    circuit->t_send_psnp[1] = 
      thread_add_timer (master,
                        send_l2_psnp,
                        circuit,
                        isis_jitter (circuit->psnp_interval[level - 1],
                                     PSNP_JITTER));
  }
  
  thread_add_event (master, isis_event_dis_status_change, circuit, 0);

  return ISIS_OK;
}

int 
isis_dr_commence (struct isis_circuit *circuit, int level)
{
  u_char old_dr[ISIS_SYS_ID_LEN + 2];
  
  zlog_info ("isis_dr_commence l%d", level);

  /* Lets keep a pause in DR election */
  circuit->u.bc.run_dr_elect[level - 1] = 0;
  if (level == 1) 
    circuit->u.bc.t_run_dr[0] = 
      thread_add_timer (master, isis_run_dr_l1, circuit,
			2 * circuit->hello_multiplier[0] * 
			circuit->hello_interval[0]); 
  else 
    circuit->u.bc.t_run_dr[1] = 
      thread_add_timer (master, isis_run_dr_l2, circuit,
			2 * circuit->hello_multiplier[1] * 
			circuit->hello_interval[1]);	      	
  circuit->u.bc.is_dr[level - 1] = 1;

  if (level == 1) {
    memcpy (old_dr, circuit->u.bc.l1_desig_is, ISIS_SYS_ID_LEN + 1);
    LSP_FRAGMENT (old_dr) = 0;
    if (LSP_PSEUDO_ID(old_dr)) {
      /* there was a dr elected, purge its LSPs from the db */
      lsp_purge_dr (old_dr, circuit, level);
    }
    memcpy (circuit->u.bc.l1_desig_is, isis->sysid, ISIS_SYS_ID_LEN);
    *(circuit->u.bc.l1_desig_is + ISIS_SYS_ID_LEN) = circuit->circuit_id;
    
    assert (circuit->circuit_id); /* must be non-zero */
    /*    if (circuit->t_send_l1_psnp)
          thread_cancel (circuit->t_send_l1_psnp); */
    lsp_l1_pseudo_generate (circuit);

    circuit->u.bc.t_run_dr[0] =
      thread_add_timer (master, isis_run_dr_l1, circuit,
                        2 * circuit->hello_interval[0]);

    circuit->t_send_csnp[0] = thread_add_timer (master,
                                                send_l1_csnp,
                                                circuit, 
                                                isis_jitter 
                                              (circuit->csnp_interval[level-1],
                                               CSNP_JITTER));
  } else {
    memcpy (old_dr, circuit->u.bc.l2_desig_is, ISIS_SYS_ID_LEN + 1);
    LSP_FRAGMENT (old_dr) = 0;
    if (LSP_PSEUDO_ID(old_dr)) {
      /* there was a dr elected, purge its LSPs from the db */
      lsp_purge_dr (old_dr, circuit, level);
    }
    memcpy (circuit->u.bc.l2_desig_is, isis->sysid, ISIS_SYS_ID_LEN);
    *(circuit->u.bc.l2_desig_is + ISIS_SYS_ID_LEN) = circuit->circuit_id;
    
    assert (circuit->circuit_id); /* must be non-zero */
    /*    if (circuit->t_send_l1_psnp)
          thread_cancel (circuit->t_send_l1_psnp); */
    lsp_l2_pseudo_generate (circuit);

    circuit->u.bc.t_run_dr[1] =
      thread_add_timer (master, isis_run_dr_l2, circuit,
                        2 * circuit->hello_interval[1]);    

    circuit->t_send_csnp[1] = 
      thread_add_timer (master,
                        send_l2_csnp,
                        circuit, 
                        isis_jitter (circuit->csnp_interval[level-1],
                                     CSNP_JITTER));
        
  } 

  thread_add_event (master, isis_event_dis_status_change, circuit, 0);
  
  return ISIS_OK;
}