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RIOT/sys/net/routing/nhdp/iib_table.c 32.2 KB
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  /*
   * Copyright (C) 2014 Freie Universitรคt Berlin
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @ingroup     nhdp
   * @{
   *
   * @file
   * @brief       Interface Information Base implementation for NHDP
   *
   * @author      Fabian Nack <nack@inf.fu-berlin.de>
   *
   * @}
   */
  
  #include "mutex.h"
  #include "timex.h"
  #include "xtimer.h"
  #include "utlist.h"
  #include "kernel_types.h"
  
  #include "rfc5444/rfc5444.h"
  #include "rfc5444/rfc5444_iana.h"
  #include "rfc5444/rfc5444_writer.h"
  
  #include "iib_table.h"
  #include "nhdp_address.h"
  #include "nhdp_metric.h"
  #include "nhdp_writer.h"
  
  #define ENABLE_DEBUG (0)
  #include "debug.h"
  
  /* Internal variables */
  static mutex_t mtx_iib_access = MUTEX_INIT;
  static iib_base_entry_t *iib_base_entry_head = NULL;
  
  #if (NHDP_METRIC == NHDP_LMT_DAT)
  static const double const_dat = (((double)DAT_CONSTANT) / DAT_MAXIMUM_LOSS);
  #endif
  
  /* Internal function prototypes */
  static void rem_link_set_entry(iib_base_entry_t *base_entry, iib_link_set_entry_t *ls_entry);
  static void cleanup_link_sets(void);
  static iib_link_set_entry_t *add_default_link_set_entry(iib_base_entry_t *base_entry, timex_t *now,
                                                          uint64_t val_time);
  static void reset_link_set_entry(iib_link_set_entry_t *ls_entry, timex_t *now, uint64_t val_time);
  static iib_link_set_entry_t *update_link_set(iib_base_entry_t *base_entry, nib_entry_t *nb_elt,
                                               timex_t *now, uint64_t val_time,
                                               uint8_t sym, uint8_t lost);
  static void release_link_tuple_addresses(iib_link_set_entry_t *ls_entry);
  
  static int update_two_hop_set(iib_base_entry_t *base_entry, iib_link_set_entry_t *ls_entry,
                                timex_t *now, uint64_t val_time);
  static int add_two_hop_entry(iib_base_entry_t *base_entry, iib_link_set_entry_t *ls_entry,
                               nhdp_addr_t *th_addr, timex_t *now, uint64_t val_time);
  static void rem_two_hop_entry(iib_base_entry_t *base_entry, iib_two_hop_set_entry_t *th_entry);
  
  static void wr_update_ls_status(iib_base_entry_t *base_entry,
                                  iib_link_set_entry_t *ls_elt, timex_t *now);
  static void update_nb_tuple_symmetry(iib_base_entry_t *base_entry,
                                       iib_link_set_entry_t *ls_entry, timex_t *now);
  static void rem_not_heard_nb_tuple(iib_link_set_entry_t *ls_entry, timex_t *now);
  
  static inline timex_t get_max_timex(timex_t time_one, timex_t time_two);
  static iib_link_tuple_status_t get_tuple_status(iib_link_set_entry_t *ls_entry, timex_t *now);
  
  #if (NHDP_METRIC == NHDP_LMT_DAT)
  static void queue_rem(uint8_t *queue);
  static uint16_t queue_sum(uint8_t *queue);
  static void dat_metric_refresh(void);
  #endif
  
  /*---------------------------------------------------------------------------*
   *                       Interface Information Base API                      *
   *---------------------------------------------------------------------------*/
  
  int iib_register_if(kernel_pid_t pid)
  {
      iib_base_entry_t *new_entry = (iib_base_entry_t *) malloc(sizeof(iib_base_entry_t));
  
      if (!new_entry) {
          /* Insufficient memory */
          return -1;
      }
  
      new_entry->if_pid = pid;
      new_entry->link_set_head = NULL;
      new_entry->two_hop_set_head = NULL;
      LL_PREPEND(iib_base_entry_head, new_entry);
  
      return 0;
  }
  
  iib_link_set_entry_t *iib_process_hello(kernel_pid_t if_pid, nib_entry_t *nb_elt,
                                          uint64_t validity_time, uint8_t is_sym_nb,
                                          uint8_t is_lost)
  {
      iib_base_entry_t *base_elt;
      iib_link_set_entry_t *ls_entry = NULL;
      timex_t now;
  
      mutex_lock(&mtx_iib_access);
  
      /* Remove link tuple addresses that are included in the Removed Addr List */
      cleanup_link_sets();
  
      LL_FOREACH(iib_base_entry_head, base_elt) {
          /* Find the link set and two hop set for the interface */
          if (base_elt->if_pid == if_pid) {
              break;
          }
      }
  
      if (base_elt) {
          xtimer_now_timex(&now);
  
          /* Create a new link tuple for the neighbor that originated the hello */
          ls_entry = update_link_set(base_elt, nb_elt, &now, validity_time, is_sym_nb, is_lost);
  
          /* Create new two hop tuples for signaled symmetric neighbors */
          if (ls_entry) {
              update_two_hop_set(base_elt, ls_entry, &now, validity_time);
          }
      }
  
      mutex_unlock(&mtx_iib_access);
  
      return ls_entry;
  }
  
  void iib_fill_wr_addresses(kernel_pid_t if_pid, struct rfc5444_writer *wr)
  {
      iib_base_entry_t *base_elt;
      iib_link_set_entry_t *ls_elt;
      nhdp_addr_entry_t *addr_elt;
      timex_t now;
  
      mutex_lock(&mtx_iib_access);
  
      xtimer_now_timex(&now);
  
      /* Before adding addresses first update the status of all link tuples */
      iib_update_lt_status(&now);
  
      /* Add all addresses of Link Tuples of the given interface's Link Set to the current HELLO */
      LL_FOREACH(iib_base_entry_head, base_elt) {
          if (base_elt->if_pid == if_pid) {
              LL_FOREACH(base_elt->link_set_head, ls_elt) {
                  if (ls_elt->last_status != IIB_LT_STATUS_PENDING) {
                      /* Exclude addresses from tuples with L_STATUS = PENDING */
                      LL_FOREACH(ls_elt->address_list_head, addr_elt) {
                          if (!NHDP_ADDR_TMP_IN_ANY(addr_elt->address)) {
                              /* Add address to the writers next packet */
                              switch (ls_elt->last_status) {
                                  case IIB_LT_STATUS_SYM:
                                      nhdp_writer_add_addr(wr, addr_elt->address,
                                                           RFC5444_ADDRTLV_LINK_STATUS,
                                                           RFC5444_LINKSTATUS_SYMMETRIC,
                                                           rfc5444_metric_encode(ls_elt->metric_in),
                                                           rfc5444_metric_encode(ls_elt->metric_out));
                                      addr_elt->address->in_tmp_table = NHDP_ADDR_TMP_SYM;
                                      break;
  
                                  case IIB_LT_STATUS_HEARD:
                                      nhdp_writer_add_addr(wr, addr_elt->address,
                                                           RFC5444_ADDRTLV_LINK_STATUS,
                                                           RFC5444_LINKSTATUS_HEARD,
                                                           rfc5444_metric_encode(ls_elt->metric_in),
                                                           rfc5444_metric_encode(ls_elt->metric_out));
                                      addr_elt->address->in_tmp_table = NHDP_ADDR_TMP_ANY;
                                      break;
  
                                  case IIB_LT_STATUS_UNKNOWN:
                                      /* Fall through */
  
                                  case IIB_LT_STATUS_LOST:
                                      nhdp_writer_add_addr(wr, addr_elt->address,
                                                           RFC5444_ADDRTLV_LINK_STATUS,
                                                           RFC5444_LINKSTATUS_LOST,
                                                           rfc5444_metric_encode(ls_elt->metric_in),
                                                           rfc5444_metric_encode(ls_elt->metric_out));
                                      addr_elt->address->in_tmp_table = NHDP_ADDR_TMP_ANY;
                                      break;
  
                                  case IIB_LT_STATUS_PENDING:
                                      /* Pending link tuples are not included */
                                      break;
  
                                  default:
                                      /* Should not happen */
                                      DEBUG("%s:%d in %s: [WARNING] Unknown link tuple status\n",
                                            RIOT_FILE_RELATIVE, __LINE__, DEBUG_FUNC);
                                      break;
                              }
                          }
                      }
                  }
              }
              /* IF's link set found */
              break;
          }
      }
  
      mutex_unlock(&mtx_iib_access);
  }
  
  void iib_update_lt_status(timex_t *now)
  {
      iib_base_entry_t *base_elt;
      iib_link_set_entry_t *ls_elt, *ls_tmp;
  
      LL_FOREACH(iib_base_entry_head, base_elt) {
          LL_FOREACH_SAFE(base_elt->link_set_head, ls_elt, ls_tmp) {
              wr_update_ls_status(base_elt, ls_elt, now);
          }
      }
  }
  
  void iib_propagate_nb_entry_change(nib_entry_t *old_entry, nib_entry_t *new_entry)
  {
      iib_base_entry_t *base_elt;
      iib_link_set_entry_t *ls_elt;
      LL_FOREACH(iib_base_entry_head, base_elt) {
          LL_FOREACH(base_elt->link_set_head, ls_elt) {
              if (ls_elt->nb_elt == old_entry) {
                  ls_elt->nb_elt = new_entry;
              }
          }
      }
  }
  
  void iib_process_metric_msg(iib_link_set_entry_t *ls_entry, uint64_t int_time)
  {
  #if (NHDP_METRIC == NHDP_LMT_HOP_COUNT)
      /* Hop metric value for an existing direct link is always 1 */
      (void)int_time;
      ls_entry->metric_in = 1;
      ls_entry->metric_out = 1;
      if (ls_entry->nb_elt) {
          ls_entry->nb_elt->metric_in = 1;
          ls_entry->nb_elt->metric_out = 1;
      }
  #elif (NHDP_METRIC == NHDP_LMT_DAT)
      /* Process required DAT metric steps */
      ls_entry->hello_interval = rfc5444_timetlv_encode(int_time);
      if (ls_entry->last_seq_no == 0) {
          timex_t now, i_time;
          xtimer_now_timex(&now);
          i_time = timex_from_uint64(int_time * US_PER_MS * DAT_HELLO_TIMEOUT_FACTOR);
          ls_entry->dat_received[0]++;
          ls_entry->dat_total[0]++;
          ls_entry->dat_time = timex_add(now, i_time);
      }
  #else
      /* NHDP_METRIC is not set properly */
      (void)ls_entry;
      (void)int_time;
      DEBUG("%s:%d in %s: [WARNING] Unknown NHDP_METRIC setting\n",
            RIOT_FILE_RELATIVE, __LINE__, DEBUG_FUNC);
  #endif
  }
  
  void iib_process_metric_pckt(iib_link_set_entry_t *ls_entry, uint32_t metric_out, uint16_t seq_no)
  {
  #if (NHDP_METRIC == NHDP_LMT_HOP_COUNT)
      /* Nothing to do here */
      (void)ls_entry;
      (void)metric_out;
      (void)seq_no;
  #elif (NHDP_METRIC == NHDP_LMT_DAT)
      /* Metric packet processing */
      if (ls_entry->last_seq_no == 0) {
          ls_entry->dat_received[0] = 1;
          ls_entry->dat_total[0] = 1;
      }
      /* Don't add values to the queue for duplicate packets */
      else if (seq_no != ls_entry->last_seq_no) {
          uint16_t seq_diff;
          if (seq_no < ls_entry->last_seq_no) {
              seq_diff = (uint16_t) ((((uint32_t) seq_no) + 0xFFFF) - ls_entry->last_seq_no);
          }
          else {
              seq_diff = seq_no - ls_entry->last_seq_no;
          }
          ls_entry->dat_total[0] += (seq_diff > NHDP_SEQNO_RESTART_DETECT) ? 1 : seq_diff;
          ls_entry->dat_received[0]++;
      }
  
      ls_entry->last_seq_no = seq_no;
      ls_entry->lost_hellos = 0;
  
      if (ls_entry->hello_interval != 0) {
          timex_t now, i_time;
          xtimer_now_timex(&now);
          i_time = timex_from_uint64(rfc5444_timetlv_decode(ls_entry->hello_interval)
                  * US_PER_MS * DAT_HELLO_TIMEOUT_FACTOR);
          ls_entry->dat_time = timex_add(now, i_time);
      }
  
      /* Refresh metric value for link tuple and corresponding neighbor tuple */
      if (ls_entry->nb_elt) {
          if ((metric_out <= ls_entry->nb_elt->metric_out) ||
                  (ls_entry->nb_elt->metric_out == NHDP_METRIC_UNKNOWN)) {
              /* Better value, use it also for your neighbor */
              ls_entry->nb_elt->metric_out = metric_out;
          }
          else if (ls_entry->metric_out == ls_entry->nb_elt->metric_out){
              /* The corresponding neighbor tuples metric needs to be updated */
              iib_base_entry_t *base_elt;
              iib_link_set_entry_t *ls_elt;
              ls_entry->nb_elt->metric_out = metric_out;
              LL_FOREACH(iib_base_entry_head, base_elt) {
                  LL_FOREACH(base_elt->link_set_head, ls_elt) {
                      if ((ls_elt->nb_elt == ls_entry->nb_elt) && (ls_elt != ls_entry)) {
                          if (ls_elt->metric_out < ls_entry->nb_elt->metric_out) {
                              /* Smaller DAT value is better */
                              ls_entry->nb_elt->metric_out = ls_elt->metric_out;
                          }
                          break;
                      }
                  }
              }
          }
      }
      ls_entry->metric_out = metric_out;
  #else
      /* NHDP_METRIC is not set properly */
      (void)ls_entry;
      (void)metric_out;
      (void)seq_no;
      DEBUG("%s:%d in %s: [WARNING] Unknown NHDP_METRIC setting\n",
            RIOT_FILE_RELATIVE, __LINE__, DEBUG_FUNC);
  #endif
  }
  
  void iib_process_metric_refresh(void)
  {
  #if (NHDP_METRIC == NHDP_LMT_HOP_COUNT)
      /* Nothing to do here */
  #elif (NHDP_METRIC == NHDP_LMT_DAT)
      dat_metric_refresh();
  #else
      /* NHDP_METRIC is not set properly */
      DEBUG("%s:%d in %s: [WARNING] Unknown NHDP_METRIC setting\n",
            RIOT_FILE_RELATIVE, __LINE__, DEBUG_FUNC);
  #endif
  }
  
  
  /*------------------------------------------------------------------------------------*/
  /*                                Internal functions                                  */
  /*------------------------------------------------------------------------------------*/
  
  /**
   * Remove addresses included in the Removed Address List from all existing Link Tuples
   */
  static void cleanup_link_sets(void)
  {
      iib_base_entry_t *base_elt;
  
      /* Loop through all link sets */
      LL_FOREACH(iib_base_entry_head, base_elt) {
          /* Loop through all link tuples of the link set */
          iib_link_set_entry_t *ls_elt, *ls_tmp;
          LL_FOREACH_SAFE(base_elt->link_set_head, ls_elt, ls_tmp) {
              /* Loop through all addresses of the link tuples */
              nhdp_addr_entry_t *lt_elt, *lt_tmp;
              LL_FOREACH_SAFE(ls_elt->address_list_head, lt_elt, lt_tmp) {
                  if (NHDP_ADDR_TMP_IN_REM_LIST(lt_elt->address)) {
                      /* Remove link tuple address if included in the Removed Addr List */
                      LL_DELETE(ls_elt->address_list_head, lt_elt);
                      nhdp_free_addr_entry(lt_elt);
                  }
              }
  
              /* Remove link tuples with empty address list */
              if (!ls_elt->address_list_head) {
                  if (ls_elt->last_status == IIB_LT_STATUS_SYM) {
                      /* Remove all two hop entries for the corresponding link tuple */
                      iib_two_hop_set_entry_t *th_elt, *th_tmp;
                      LL_FOREACH_SAFE(base_elt->two_hop_set_head, th_elt, th_tmp) {
                          if (th_elt->ls_elt == ls_elt) {
                              rem_two_hop_entry(base_elt, th_elt);
                          }
                      }
                  }
  
                  rem_link_set_entry(base_elt, ls_elt);
              }
          }
      }
  }
  
  /**
   * Update the Link Set for the receiving interface during HELLO message processing
   */
  static iib_link_set_entry_t *update_link_set(iib_base_entry_t *base_entry, nib_entry_t *nb_elt,
                                               timex_t *now, uint64_t val_time,
                                               uint8_t sym, uint8_t lost)
  {
      iib_link_set_entry_t *ls_elt, *ls_tmp;
      iib_link_set_entry_t *matching_lt = NULL;
      nhdp_addr_entry_t *lt_elt;
      timex_t v_time, l_hold;
      uint8_t matches = 0;
  
      /* Loop through every link tuple of the interface to update the link set */
      LL_FOREACH_SAFE(base_entry->link_set_head, ls_elt, ls_tmp) {
          /* Loop through all addresses of the link tuple */
          LL_FOREACH(ls_elt->address_list_head, lt_elt) {
              if (NHDP_ADDR_TMP_IN_SEND_LIST(lt_elt->address)) {
                  /* If link tuple address matches a sending addr we found a fitting tuple */
                  matches++;
  
                  if (matches > 1) {
                      /* Multiple matching link tuples, delete the previous one */
                      if (matching_lt->last_status == IIB_LT_STATUS_SYM) {
                          update_nb_tuple_symmetry(base_entry, matching_lt, now);
                      }
  
                      rem_link_set_entry(base_entry, matching_lt);
                  }
  
                  matching_lt = ls_elt;
                  break;
              }
          }
      }
  
      if (matches > 1) {
          /* Multiple matching link tuples, reset the last one for reuse */
          if (matching_lt->last_status == IIB_LT_STATUS_SYM) {
              update_nb_tuple_symmetry(base_entry, matching_lt, now);
          }
  
          reset_link_set_entry(matching_lt, now, val_time);
      }
      else if (matches == 1) {
          /* A single matching link tuple, only release the address list */
          release_link_tuple_addresses(matching_lt);
      }
      else {
          /* No single matching link tuple existant, create a new one */
          matching_lt = add_default_link_set_entry(base_entry, now, val_time);
  
          if (!matching_lt) {
              /* Insufficient memory */
              return NULL;
          }
      }
  
      v_time = timex_from_uint64(val_time * US_PER_MS);
      l_hold = timex_from_uint64(((uint64_t)NHDP_L_HOLD_TIME_MS) * US_PER_MS);
  
      /* Set Sending Address List as this tuples address list */
      matching_lt->address_list_head = nhdp_generate_addr_list_from_tmp(NHDP_ADDR_TMP_SEND_LIST);
  
      if (!matching_lt->address_list_head) {
          /* Insufficient memory */
          rem_link_set_entry(base_entry, matching_lt);
          return NULL;
      }
  
      matching_lt->nb_elt = nb_elt;
  
      /* Set values dependent on link status */
      if (sym) {
          if (matching_lt->last_status != IIB_LT_STATUS_SYM) {
              /* Set corresponding neighbor tuple to symmetric (Section 13.1 of RFC 6130) */
              if (matching_lt->nb_elt) {
                  nib_set_nb_entry_sym(matching_lt->nb_elt);
              }
          }
  
          matching_lt->sym_time = timex_add(*now, v_time);
          matching_lt->last_status = IIB_LT_STATUS_SYM;
      }
      else if (lost) {
          matching_lt->sym_time.microseconds = 0;
          matching_lt->sym_time.seconds = 0;
  
          if (matching_lt->last_status == IIB_LT_STATUS_SYM) {
              update_nb_tuple_symmetry(base_entry, matching_lt, now);
          }
  
          if (get_tuple_status(matching_lt, now) == IIB_LT_STATUS_HEARD) {
              matching_lt->last_status = IIB_LT_STATUS_HEARD;
              matching_lt->exp_time = timex_add(*now, l_hold);
          }
          else {
              matching_lt->last_status = IIB_LT_STATUS_UNKNOWN;
          }
      }
  
      /* Set time values */
      matching_lt->heard_time = get_max_timex(timex_add(*now, v_time), matching_lt->sym_time);
  
      if (matching_lt->pending) {
          /* L_status is PENDING */
          matching_lt->exp_time = get_max_timex(matching_lt->exp_time, matching_lt->heard_time);
      }
      else if (!matching_lt->lost) {
          if ((timex_cmp(matching_lt->sym_time, *now) == 1)
              || (timex_cmp(matching_lt->heard_time, *now) == 1)) {
              /* L_status is HEARD or SYMMETRIC */
              matching_lt->exp_time = get_max_timex(matching_lt->exp_time,
                                                    timex_add(matching_lt->heard_time, l_hold));
          }
      }
  
      return matching_lt;
  }
  
  /**
   * Update the status of a link tuple and process necessary changes and execute
   * necessary changes in the 2-Hop Set and in the Neighbor Information Base
   * Implements logic of Section 13 of RFC 6130
   */
  static void wr_update_ls_status(iib_base_entry_t *base_entry,
                                  iib_link_set_entry_t *ls_elt, timex_t *now)
  {
      if (timex_cmp(ls_elt->exp_time, *now) != 1) {
          /* Entry expired and has to be removed */
          if (ls_elt->last_status == IIB_LT_STATUS_SYM) {
              update_nb_tuple_symmetry(base_entry, ls_elt, now);
          }
  
          rem_not_heard_nb_tuple(ls_elt, now);
          rem_link_set_entry(base_entry, ls_elt);
      }
      else if ((ls_elt->last_status == IIB_LT_STATUS_SYM)
               && (timex_cmp(ls_elt->sym_time, *now) != 1)) {
          /* Status changed from SYMMETRIC to HEARD */
          update_nb_tuple_symmetry(base_entry, ls_elt, now);
          ls_elt->last_status = IIB_LT_STATUS_HEARD;
  
          if (timex_cmp(ls_elt->heard_time, *now) != 1) {
              /* New status is LOST (equals IIB_LT_STATUS_UNKNOWN) */
              rem_not_heard_nb_tuple(ls_elt, now);
              ls_elt->nb_elt = NULL;
              ls_elt->last_status = IIB_LT_STATUS_UNKNOWN;
          }
      }
      else if ((ls_elt->last_status == IIB_LT_STATUS_HEARD)
               && (timex_cmp(ls_elt->heard_time, *now) != 1)) {
          /* Status changed from HEARD to LOST (equals IIB_LT_STATUS_UNKNOWN) */
          rem_not_heard_nb_tuple(ls_elt, now);
          ls_elt->nb_elt = NULL;
          ls_elt->last_status = IIB_LT_STATUS_UNKNOWN;
      }
  }
  
  /**
   * Add a new Link Tuple with default values to the given Link Set
   */
  static iib_link_set_entry_t *add_default_link_set_entry(iib_base_entry_t *base_entry, timex_t *now,
                                                          uint64_t val_time)
  {
      iib_link_set_entry_t *new_entry;
  
      new_entry = (iib_link_set_entry_t *) malloc(sizeof(iib_link_set_entry_t));
  
      if (!new_entry) {
          /* Insufficient memory */
          return NULL;
      }
  
      new_entry->address_list_head = NULL;
      reset_link_set_entry(new_entry, now, val_time);
      LL_PREPEND(base_entry->link_set_head, new_entry);
  
      return new_entry;
  }
  
  /**
   * Reset a given Link Tuple for reusage
   */
  static void reset_link_set_entry(iib_link_set_entry_t *ls_entry, timex_t *now, uint64_t val_time)
  {
      timex_t v_time = timex_from_uint64(val_time * US_PER_MS);
  
      release_link_tuple_addresses(ls_entry);
      ls_entry->sym_time.microseconds = 0;
      ls_entry->sym_time.seconds = 0;
      ls_entry->heard_time.microseconds = 0;
      ls_entry->heard_time.seconds = 0;
      ls_entry->pending = NHDP_INITIAL_PENDING;
      ls_entry->lost = 0;
      ls_entry->exp_time = timex_add(*now, v_time);
      ls_entry->nb_elt = NULL;
      ls_entry->last_status = IIB_LT_STATUS_UNKNOWN;
      ls_entry->metric_in = NHDP_METRIC_UNKNOWN;
      ls_entry->metric_out = NHDP_METRIC_UNKNOWN;
  #if (NHDP_METRIC == NHDP_LMT_DAT)
      memset(ls_entry->dat_received, 0, NHDP_Q_MEM_LENGTH);
      memset(ls_entry->dat_total, 0, NHDP_Q_MEM_LENGTH);
      ls_entry->dat_time.microseconds = 0;
      ls_entry->dat_time.seconds = 0;
      ls_entry->hello_interval = 0;
      ls_entry->lost_hellos = 0;
      ls_entry->rx_bitrate = 100000;
      ls_entry->last_seq_no = 0;
  #endif
  }
  
  /**
   * Remove a given Link Tuple
   */
  static void rem_link_set_entry(iib_base_entry_t *base_entry, iib_link_set_entry_t *ls_entry)
  {
      LL_DELETE(base_entry->link_set_head, ls_entry);
      release_link_tuple_addresses(ls_entry);
      free(ls_entry);
  }
  
  /**
   * Free all address entries of a link tuple
   */
  static void release_link_tuple_addresses(iib_link_set_entry_t *ls_entry)
  {
      nhdp_free_addr_list(ls_entry->address_list_head);
      ls_entry->address_list_head = NULL;
  }
  
  /**
   * Update the 2-Hop Set during HELLO message processing
   */
  static int update_two_hop_set(iib_base_entry_t *base_entry, iib_link_set_entry_t *ls_entry,
                                timex_t *now, uint64_t val_time)
  {
      /* Check whether a corresponding link tuple was created */
      if (ls_entry == NULL) {
          return -1;
      }
  
      /* If the link to the neighbor is still symmetric */
      if (get_tuple_status(ls_entry, now) == IIB_LT_STATUS_SYM) {
          iib_two_hop_set_entry_t *ths_elt, *ths_tmp;
          nhdp_addr_t *addr_elt;
  
          /* Loop through all the two hop tuples of the two hop set */
          LL_FOREACH_SAFE(base_entry->two_hop_set_head, ths_elt, ths_tmp) {
              if (timex_cmp(ths_elt->exp_time, *now) != 1) {
                  /* Entry is expired, remove it */
                  rem_two_hop_entry(base_entry, ths_elt);
              }
              else if (ths_elt->ls_elt == ls_entry) {
                  if (ths_elt->th_nb_addr->in_tmp_table &
                      (NHDP_ADDR_TMP_TH_REM_LIST | NHDP_ADDR_TMP_TH_SYM_LIST)) {
                      rem_two_hop_entry(base_entry, ths_elt);
                  }
              }
          }
  
          /* Add a new entry for every signaled symmetric neighbor address */
          LL_FOREACH(nhdp_get_addr_db_head(), addr_elt) {
              if (NHDP_ADDR_TMP_IN_TH_SYM_LIST(addr_elt)) {
                  if (add_two_hop_entry(base_entry, ls_entry, addr_elt, now, val_time)) {
                      /* No more memory available, return error */
                      return -1;
                  }
              }
          }
      }
  
      return 0;
  }
  
  /**
   * Add a 2-Hop Tuple for a given address
   */
  static int add_two_hop_entry(iib_base_entry_t *base_entry, iib_link_set_entry_t *ls_entry,
                               nhdp_addr_t *th_addr, timex_t *now, uint64_t val_time)
  {
      iib_two_hop_set_entry_t *new_entry;
      timex_t v_time = timex_from_uint64(val_time * US_PER_MS);
  
      new_entry = (iib_two_hop_set_entry_t *) malloc(sizeof(iib_two_hop_set_entry_t));
  
      if (!new_entry) {
          /* Insufficient memory */
          return -1;
      }
  
      /* Increment usage counter of address in central NHDP address storage */
      th_addr->usg_count++;
      new_entry->th_nb_addr = th_addr;
      new_entry->ls_elt = ls_entry;
      new_entry->exp_time = timex_add(*now, v_time);
      if (th_addr->tmp_metric_val != NHDP_METRIC_UNKNOWN) {
          new_entry->metric_in = rfc5444_metric_decode(th_addr->tmp_metric_val);
          new_entry->metric_out = rfc5444_metric_decode(th_addr->tmp_metric_val);
      }
      else {
          new_entry->metric_in = NHDP_METRIC_UNKNOWN;
          new_entry->metric_out = NHDP_METRIC_UNKNOWN;
      }
  
      LL_PREPEND(base_entry->two_hop_set_head, new_entry);
  
      return 0;
  }
  
  /**
   * Remove a given 2-Hop Tuple
   */
  static void rem_two_hop_entry(iib_base_entry_t *base_entry, iib_two_hop_set_entry_t *th_entry)
  {
      LL_DELETE(base_entry->two_hop_set_head, th_entry);
      nhdp_decrement_addr_usage(th_entry->th_nb_addr);
      free(th_entry);
  }
  
  /**
   * Remove all corresponding two hop entries for a given link tuple that lost symmetry status.
   * Additionally reset the neighbor tuple's symmmetry flag (for the neighbor tuple this link
   * tuple is represented in), if no more corresponding symmetric link tuples are left.
   * Implements section 13.2 of RFC 6130
   */
  static void update_nb_tuple_symmetry(iib_base_entry_t *base_entry,
                                       iib_link_set_entry_t *ls_entry, timex_t *now)
  {
      iib_two_hop_set_entry_t *th_elt, *th_tmp;
  
      /* First remove all two hop entries for the corresponding link tuple */
      LL_FOREACH_SAFE(base_entry->two_hop_set_head, th_elt, th_tmp) {
          if (th_elt->ls_elt == ls_entry) {
              rem_two_hop_entry(base_entry, th_elt);
          }
      }
  
      /* Afterwards check the neighbor tuple containing the link tuple's addresses */
      if ((ls_entry->nb_elt != NULL) && (ls_entry->nb_elt->symmetric == 1)) {
          iib_base_entry_t *base_tmp;
          LL_FOREACH(iib_base_entry_head, base_tmp) {
              iib_link_set_entry_t *ls_tmp;
              LL_FOREACH(base_tmp->link_set_head, ls_tmp) {
                  if ((ls_entry->nb_elt == ls_tmp->nb_elt) && (ls_entry != ls_tmp)) {
                      if (timex_cmp(ls_tmp->sym_time, *now) == 1) {
                          return;
                      }
                  }
              }
          }
  
          /* No remaining symmetric link tuple for the neighbor tuple */
          nib_reset_nb_entry_sym(ls_entry->nb_elt, now);
      }
  }
  
  /**
   * Remove a neighbor tuple if no more corresponding heard link tuples are left
   * Implements section 13.3 of RFC 6130
   */
  static void rem_not_heard_nb_tuple(iib_link_set_entry_t *ls_entry, timex_t *now)
  {
      /* Check whether the corresponding neighbor tuple still exists */
      if (ls_entry->nb_elt) {
          iib_base_entry_t *base_tmp;
          LL_FOREACH(iib_base_entry_head, base_tmp) {
              iib_link_set_entry_t *ls_tmp;
              LL_FOREACH(base_tmp->link_set_head, ls_tmp) {
                  if ((ls_entry->nb_elt == ls_tmp->nb_elt) && (ls_entry != ls_tmp)) {
                      if (timex_cmp(ls_tmp->heard_time, *now) == 1) {
                          return;
                      }
  
                      ls_tmp->nb_elt = NULL;
                  }
              }
          }
  
          /* No remaining heard link tuple for the neighbor tuple */
          nib_rem_nb_entry(ls_entry->nb_elt);
      }
  }
  
  /**
   * Get the L_STATUS value of a given link tuple
   */
  static iib_link_tuple_status_t get_tuple_status(iib_link_set_entry_t *ls_entry, timex_t *now)
  {
      if (ls_entry->pending) {
          return IIB_LT_STATUS_PENDING;
      }
      else if (ls_entry->lost) {
          return IIB_LT_STATUS_LOST;
      }
      else if (timex_cmp(ls_entry->sym_time, *now) == 1) {
          return IIB_LT_STATUS_SYM;
      }
      else if (timex_cmp(ls_entry->heard_time, *now) == 1) {
          return IIB_LT_STATUS_HEARD;
      }
  
      return IIB_LT_STATUS_UNKNOWN;
  }
  
  /**
   * Get the later one of two timex representation
   */
  static inline timex_t get_max_timex(timex_t time_one, timex_t time_two)
  {
      if (timex_cmp(time_one, time_two) != -1) {
          return time_one;
      }
  
      return time_two;
  }
  
  #if (NHDP_METRIC == NHDP_LMT_DAT)
  /**
   * Sum all elements in the queue
   */
  static uint16_t queue_sum(uint8_t *queue)
  {
      uint16_t sum = 0;
  
      for (int i = 0; i < NHDP_Q_MEM_LENGTH; i++) {
          sum += queue[i];
      }
  
      return sum;
  }
  
  /**
   * Remove the oldest element in the queue
   */
  static void queue_rem(uint8_t *queue)
  {
      uint8_t temp;
      uint8_t prev_value = queue[0];
  
      /* Clear spot for a new element */
      queue[0] = 0;
  
      /* Shift elements */
      for (int i = 1; i < NHDP_Q_MEM_LENGTH; i++) {
          temp = queue[i];
          queue[i] = prev_value;
          prev_value = temp;
      }
  }
  
  /**
   * Update DAT metric values for all Link Tuples
   */
  static void dat_metric_refresh(void)
  {
      iib_base_entry_t *base_elt;
      iib_link_set_entry_t *ls_elt;
      uint32_t metric_temp;
      double sum_total, sum_rcvd, loss;
  
      LL_FOREACH(iib_base_entry_head, base_elt) {
          LL_FOREACH(base_elt->link_set_head, ls_elt) {
              sum_rcvd = queue_sum(ls_elt->dat_received);
              sum_total = queue_sum(ls_elt->dat_total);
              metric_temp = ls_elt->metric_in;
  
              if ((ls_elt->hello_interval != 0) && (ls_elt->lost_hellos > 0)) {
                  /* Compute lost time proportion */
                  loss = (((double)ls_elt->hello_interval) * ((double)ls_elt->lost_hellos))
                          / DAT_MEMORY_LENGTH;
                  if (loss >= 1.0) {
                      sum_rcvd = 0.0;
                  }
                  else {
                      sum_rcvd *= (1.0 - loss);
                  }
              }
  
              if (sum_rcvd < 1.0) {
                  ls_elt->metric_in = NHDP_METRIC_MAXIMUM;
              }
              else {
                  loss = sum_total / sum_rcvd;
                  if (loss > DAT_MAXIMUM_LOSS) {
                      loss = DAT_MAXIMUM_LOSS;
                  }
                  ls_elt->metric_in = (const_dat * loss) / (ls_elt->rx_bitrate / DAT_MINIMUM_BITRATE);
                  if (ls_elt->metric_in > NHDP_METRIC_MAXIMUM) {
                      ls_elt->metric_in = NHDP_METRIC_MAXIMUM;
                  }
              }
  
              if (ls_elt->nb_elt) {
                  if (ls_elt->metric_in <= ls_elt->nb_elt->metric_in ||
                          (ls_elt->nb_elt->metric_in == NHDP_METRIC_UNKNOWN)) {
                      /* Better value, use it also for your neighbor */
                      ls_elt->nb_elt->metric_in = ls_elt->metric_in;
                  }
                  else if (metric_temp == ls_elt->nb_elt->metric_in){
                      /* The corresponding neighbor tuples metric needs to be updated */
                      iib_base_entry_t *base_entry;
                      iib_link_set_entry_t *ls_entry;
                      ls_elt->nb_elt->metric_in = ls_elt->metric_in;
                      LL_FOREACH(iib_base_entry_head, base_entry) {
                          LL_FOREACH(base_entry->link_set_head, ls_entry) {
                              if ((ls_elt->nb_elt == ls_entry->nb_elt) && (ls_elt != ls_entry)) {
                                  if (ls_entry->metric_in < ls_elt->nb_elt->metric_in) {
                                      /* Smaller DAT value is better */
                                      ls_elt->nb_elt->metric_in = ls_entry->metric_in;
                                  }
                                  break;
                              }
                          }
                      }
                  }
              }
  
              queue_rem(ls_elt->dat_received);
              queue_rem(ls_elt->dat_total);
          }
      }
  }
  #endif