/**
 * ospf_bfd.c: OSPF BFD handling routines
 *
 * @copyright Copyright (C) 2015 Cumulus Networks, Inc.
 *
 * This file is part of GNU Zebra.
 *
 * GNU Zebra 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, or (at your option) any
 * later version.
 *
 * GNU Zebra 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 GNU Zebra; see the file COPYING.  If not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#include <zebra.h>

#include "command.h"
#include "linklist.h"
#include "memory.h"
#include "prefix.h"
#include "thread.h"
#include "buffer.h"
#include "stream.h"
#include "zclient.h"
#include "vty.h"
#include "table.h"
#include "bfd.h"
#include "ospfd.h"
#include "ospf_asbr.h"
#include "ospf_lsa.h"
#include "ospf_lsdb.h"
#include "ospf_neighbor.h"
#include "ospf_interface.h"
#include "ospf_nsm.h"
#include "ospf_bfd.h"
#include "ospf_dump.h"
#include "ospf_vty.h"

extern struct zclient *zclient;

/*
 * ospf_bfd_reg_dereg_nbr - Register/Deregister a neighbor with BFD through
 *                          zebra for starting/stopping the monitoring of
 *                          the neighbor rechahability.
 */
static void
ospf_bfd_reg_dereg_nbr (struct ospf_neighbor *nbr, int command)
{
  struct ospf_interface *oi = nbr->oi;
  struct interface *ifp = oi->ifp;
  struct ospf_if_params *params;
  struct bfd_info *bfd_info;

  /* Check if BFD is enabled */
  params = IF_DEF_PARAMS (ifp);

  /* Check if BFD is enabled */
  if (!params->bfd_info)
    return;
  bfd_info = (struct bfd_info *)params->bfd_info;

  if (IS_DEBUG_OSPF(zebra, ZEBRA_INTERFACE))
    zlog_debug ("%s nbr (%s) with BFD",
                  bfd_get_command_dbg_str(command),
                  inet_ntoa (nbr->src));

  bfd_peer_sendmsg (zclient, bfd_info, AF_INET,
                    &nbr->src, NULL, ifp->name, 0, 0, command, 0);
}

/*
 * ospf_bfd_trigger_event - Neighbor is registered/deregistered with BFD when
 *                          neighbor state is changed to/from 2way.
 */
void
ospf_bfd_trigger_event(struct ospf_neighbor *nbr, int old_state, int state)
{
  if ((old_state < NSM_TwoWay) && (state >= NSM_TwoWay))
    ospf_bfd_reg_dereg_nbr(nbr, ZEBRA_BFD_DEST_REGISTER);
  else if ((old_state >= NSM_TwoWay) && (state < NSM_TwoWay))
    ospf_bfd_reg_dereg_nbr(nbr, ZEBRA_BFD_DEST_DEREGISTER);
}

/*
 * ospf_bfd_reg_dereg_all_nbr - Register/Deregister all neighbors associated
 *                              with a interface with BFD through
 *                              zebra for starting/stopping the monitoring of
 *                              the neighbor rechahability.
 */
static int
ospf_bfd_reg_dereg_all_nbr (struct interface *ifp, int command)
{
  struct ospf_interface *oi;
  struct route_table *nbrs;
  struct ospf_neighbor *nbr;
  struct route_node *irn;
  struct route_node *nrn;

  for (irn = route_top (IF_OIFS (ifp)); irn; irn = route_next (irn))
    {
      if ((oi = irn->info) == NULL)
        continue;

      if ((nbrs = oi->nbrs) == NULL)
        continue;

      for (nrn = route_top (nbrs); nrn; nrn = route_next (nrn))
        {
          if ((nbr = nrn->info) == NULL || nbr == oi->nbr_self)
            continue;

          if (nbr->state < NSM_TwoWay)
            continue;

          ospf_bfd_reg_dereg_nbr(nbr, command);
        }
    }

  return 0;
}

/*
 * ospf_bfd_nbr_replay - Replay all the neighbors that have BFD enabled
 *                       to zebra
 */
static int
ospf_bfd_nbr_replay (int command, struct zclient *client, zebra_size_t length)
{
  struct listnode *inode, *node, *onode;
  struct ospf *ospf;
  struct ospf_interface *oi;
  struct route_table *nbrs;
  struct route_node *rn;
  struct ospf_neighbor *nbr;
  struct ospf_if_params *params;

  if (IS_DEBUG_OSPF(zebra, ZEBRA_INTERFACE))
    {
      zlog_debug("Zebra: BFD Dest replay request");
    }

  /* Replay the neighbor, if BFD is enabled in BGP */
  for (ALL_LIST_ELEMENTS (om->ospf, node, onode, ospf))
    {
      for (ALL_LIST_ELEMENTS_RO (ospf->oiflist, inode, oi))
        {
          if ((nbrs = oi->nbrs) == NULL)
            continue;

          params = IF_DEF_PARAMS (oi->ifp);
          if (!params->bfd_info)
            continue;

          for (rn = route_top (nbrs); rn; rn = route_next (rn))
            {
              if ((nbr = rn->info) == NULL || nbr == oi->nbr_self)
                continue;

              if (nbr->state < NSM_TwoWay)
                continue;

              if (IS_DEBUG_OSPF(zebra, ZEBRA_INTERFACE))
                zlog_debug ("Replaying nbr (%s) to BFD", inet_ntoa (nbr->src));

              ospf_bfd_reg_dereg_nbr(nbr, ZEBRA_BFD_DEST_UPDATE);
            }
        }
    }
  return 0;
}

/*
 * ospf_bfd_interface_dest_down - Find the neighbor for which the BFD status
 *                                has changed and bring down the neighbor
 *                                connectivity.
 */
static int
ospf_bfd_interface_dest_down (int command, struct zclient *zclient,
                              zebra_size_t length)
{
  struct interface *ifp;
  struct ospf_interface *oi;
  struct ospf_if_params *params;
  struct ospf_neighbor *nbr;
  struct route_node *node;
  struct prefix p;

  ifp = bfd_get_peer_info (zclient->ibuf, &p, NULL);

  if ((ifp == NULL) || (p.family != AF_INET))
    return 0;

  if (IS_DEBUG_OSPF (zebra, ZEBRA_INTERFACE))
    {
      char buf[128];
      prefix2str(&p, buf, sizeof(buf));
      zlog_debug("Zebra: interface %s bfd destination %s down", ifp->name, buf);
    }

  params = IF_DEF_PARAMS (ifp);
  if (!params->bfd_info)
    return 0;

  for (node = route_top (IF_OIFS (ifp)); node; node = route_next (node))
    {
      if ((oi = node->info) == NULL)
        continue;

      nbr = ospf_nbr_lookup_by_addr (oi->nbrs, &p.u.prefix4);
      if (!nbr)
        continue;

      if (IS_DEBUG_OSPF (nsm, NSM_EVENTS))
        zlog_debug ("NSM[%s:%s]: BFD Down",
                    IF_NAME (nbr->oi), inet_ntoa (nbr->address.u.prefix4));

      OSPF_NSM_EVENT_SCHEDULE (nbr, NSM_InactivityTimer);
    }

  return 0;
}

/*
 * ospf_bfd_write_config - Write the interface BFD configuration.
 */
void
ospf_bfd_write_config(struct vty *vty, struct ospf_if_params *params)

{
  struct bfd_info *bfd_info;

  if (!params->bfd_info)
    return;

  bfd_info = (struct bfd_info *)params->bfd_info;

  if (CHECK_FLAG(bfd_info->flags, BFD_FLAG_PARAM_CFG))
    vty_out (vty, " ip ospf bfd %d %d %d%s",
              bfd_info->detect_mult, bfd_info->required_min_rx,
              bfd_info->desired_min_tx, VTY_NEWLINE);
  else
    vty_out (vty, " ip ospf bfd%s", VTY_NEWLINE);
}


/*
 * ospf_bfd_if_param_set - Set the configured BFD paramter values for
 *                         interface.
 */
static void
ospf_bfd_if_param_set (struct interface *ifp, u_int32_t min_rx,
                       u_int32_t min_tx, u_int8_t detect_mult, int defaults)
{
  struct ospf_if_params *params;
  int command = 0;

  params = IF_DEF_PARAMS (ifp);

  bfd_set_param(&(params->bfd_info), min_rx, min_tx, detect_mult,
                defaults, &command);
  if (command)
    ospf_bfd_reg_dereg_all_nbr(ifp, command);
}


DEFUN (ip_ospf_bfd,
       ip_ospf_bfd_cmd,
       "ip ospf bfd",
       "IP Information\n"
       "OSPF interface commands\n"
       "Enables BFD support\n")
{
  struct interface *ifp = (struct interface *) vty->index;

  assert (ifp);
  ospf_bfd_if_param_set (ifp, BFD_DEF_MIN_RX, BFD_DEF_MIN_TX,
                         BFD_DEF_DETECT_MULT, 1);

  return CMD_SUCCESS;
}

DEFUN (ip_ospf_bfd_param,
       ip_ospf_bfd_param_cmd,
       "ip ospf bfd " BFD_CMD_DETECT_MULT_RANGE BFD_CMD_MIN_RX_RANGE BFD_CMD_MIN_TX_RANGE,
       "IP Information\n"
       "OSPF interface commands\n"
       "Enables BFD support\n"
       "Detect Multiplier\n"
       "Required min receive interval\n"
       "Desired min transmit interval\n")
{
  struct interface *ifp = (struct interface *) vty->index;
  u_int32_t rx_val;
  u_int32_t tx_val;
  u_int8_t dm_val;
  int ret;

  assert (ifp);

  if ((ret = bfd_validate_param (vty, argv[0], argv[1], argv[2], &dm_val,
                                 &rx_val, &tx_val)) != CMD_SUCCESS)
    return ret;

  ospf_bfd_if_param_set (ifp, rx_val, tx_val, dm_val, 0);

  return CMD_SUCCESS;
}

DEFUN (no_ip_ospf_bfd,
       no_ip_ospf_bfd_cmd,
       "no ip ospf bfd",
       NO_STR
       "IP Information\n"
       "OSPF interface commands\n"
       "Disables BFD support\n")
{
  struct interface *ifp = (struct interface *)vty->index;
  struct ospf_if_params *params;

  assert (ifp);

  params = IF_DEF_PARAMS (ifp);
  if (params->bfd_info)
    {
      ospf_bfd_reg_dereg_all_nbr(ifp, ZEBRA_BFD_DEST_DEREGISTER);
      bfd_info_free(&(params->bfd_info));
    }

  return CMD_SUCCESS;
}

void
ospf_bfd_init(void)
{
  /* Initialize BFD client functions */
  zclient->interface_bfd_dest_down = ospf_bfd_interface_dest_down;
  zclient->bfd_dest_replay = ospf_bfd_nbr_replay;

  /* Install BFD command */
  install_element (INTERFACE_NODE, &ip_ospf_bfd_cmd);
  install_element (INTERFACE_NODE, &ip_ospf_bfd_param_cmd);
  install_element (INTERFACE_NODE, &no_ip_ospf_bfd_cmd);
}