/src/frr/bgpd/bgp_nht.c

Source (jump to first uncovered line)
// SPDX-License-Identifier: GPL-2.0-or-later
/* BGP Nexthop tracking
 * Copyright (C) 2013 Cumulus Networks, Inc.
 */

#include <zebra.h>

#include "command.h"
#include "frrevent.h"
#include "prefix.h"
#include "zclient.h"
#include "stream.h"
#include "network.h"
#include "log.h"
#include "memory.h"
#include "nexthop.h"
#include "vrf.h"
#include "filter.h"
#include "nexthop_group.h"

#include "bgpd/bgpd.h"
#include "bgpd/bgp_table.h"
#include "bgpd/bgp_route.h"
#include "bgpd/bgp_attr.h"
#include "bgpd/bgp_nexthop.h"
#include "bgpd/bgp_debug.h"
#include "bgpd/bgp_errors.h"
#include "bgpd/bgp_nht.h"
#include "bgpd/bgp_fsm.h"
#include "bgpd/bgp_zebra.h"
#include "bgpd/bgp_flowspec_util.h"
#include "bgpd/bgp_evpn.h"
#include "bgpd/bgp_rd.h"
#include "bgpd/bgp_mplsvpn.h"

extern struct zclient *zclient;

static void register_zebra_rnh(struct bgp_nexthop_cache *bnc);
static void unregister_zebra_rnh(struct bgp_nexthop_cache *bnc);
static int make_prefix(int afi, struct bgp_path_info *pi, struct prefix *p);
static void bgp_nht_ifp_initial(struct event *thread);

static int bgp_isvalid_nexthop(struct bgp_nexthop_cache *bnc)
{
  return (bgp_zebra_num_connects() == 0
    || (bnc && CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID)
        && bnc->nexthop_num > 0));
}

static int bgp_isvalid_nexthop_for_ebgp(struct bgp_nexthop_cache *bnc,
          struct bgp_path_info *path)
{
  struct interface *ifp = NULL;
  struct nexthop *nexthop;
  struct bgp_interface *iifp;
  struct peer *peer;

  if (!path->extra || !path->extra->peer_orig)
    return false;

  peer = path->extra->peer_orig;

  /* only connected ebgp peers are valid */
  if (peer->sort != BGP_PEER_EBGP || peer->ttl != BGP_DEFAULT_TTL ||
      CHECK_FLAG(peer->flags, PEER_FLAG_DISABLE_CONNECTED_CHECK) ||
      CHECK_FLAG(peer->bgp->flags, BGP_FLAG_DISABLE_NH_CONNECTED_CHK))
    return false;

  for (nexthop = bnc->nexthop; nexthop; nexthop = nexthop->next) {
    if (nexthop->type == NEXTHOP_TYPE_IFINDEX ||
        nexthop->type == NEXTHOP_TYPE_IPV4_IFINDEX ||
        nexthop->type == NEXTHOP_TYPE_IPV6_IFINDEX) {
      ifp = if_lookup_by_index(
        bnc->ifindex ? bnc->ifindex : nexthop->ifindex,
        bnc->bgp->vrf_id);
    }
    if (!ifp)
      continue;
    iifp = ifp->info;
    if (CHECK_FLAG(iifp->flags, BGP_INTERFACE_MPLS_BGP_FORWARDING))
      return true;
  }
  return false;
}

static int bgp_isvalid_nexthop_for_mplsovergre(struct bgp_nexthop_cache *bnc,
                 struct bgp_path_info *path)
{
  struct interface *ifp = NULL;
  struct nexthop *nexthop;

  for (nexthop = bnc->nexthop; nexthop; nexthop = nexthop->next) {
    if (nexthop->type != NEXTHOP_TYPE_BLACKHOLE) {
      ifp = if_lookup_by_index(
        bnc->ifindex ? bnc->ifindex : nexthop->ifindex,
        bnc->bgp->vrf_id);
      if (ifp && (ifp->ll_type == ZEBRA_LLT_IPGRE ||
            ifp->ll_type == ZEBRA_LLT_IP6GRE))
        break;
    }
  }
  if (!ifp)
    return false;

  if (CHECK_FLAG(path->attr->rmap_change_flags,
           BATTR_RMAP_L3VPN_ACCEPT_GRE))
    return true;

  return false;
}

static int bgp_isvalid_nexthop_for_mpls(struct bgp_nexthop_cache *bnc,
          struct bgp_path_info *path)
{
  /*
   * - In the case of MPLS-VPN, the label is learned from LDP or other
   * protocols, and nexthop tracking is enabled for the label.
   * The value is recorded as BGP_NEXTHOP_LABELED_VALID.
   * - In the case of SRv6-VPN, we need to track the reachability to the
   * SID (in other words, IPv6 address). As in MPLS, we need to record
   * the value as BGP_NEXTHOP_SID_VALID. However, this function is
   * currently not implemented, and this function assumes that all
   * Transit routes for SRv6-VPN are valid.
   * - Otherwise check for mpls-gre acceptance
   */
  return (bgp_zebra_num_connects() == 0 ||
    (bnc && (bnc->nexthop_num > 0 &&
       (CHECK_FLAG(path->flags, BGP_PATH_ACCEPT_OWN) ||
        CHECK_FLAG(bnc->flags, BGP_NEXTHOP_LABELED_VALID) ||
        bnc->bgp->srv6_enabled ||
        bgp_isvalid_nexthop_for_ebgp(bnc, path) ||
        bgp_isvalid_nexthop_for_mplsovergre(bnc, path)))));
}

static void bgp_unlink_nexthop_check(struct bgp_nexthop_cache *bnc)
{
  if (LIST_EMPTY(&(bnc->paths)) && !bnc->nht_info) {
    if (BGP_DEBUG(nht, NHT))
      zlog_debug("%s: freeing bnc %pFX(%d)(%u)(%s)", __func__,
           &bnc->prefix, bnc->ifindex, bnc->srte_color,
           bnc->bgp->name_pretty);
    /* only unregister if this is the last nh for this prefix*/
    if (!bnc_existing_for_prefix(bnc))
      unregister_zebra_rnh(bnc);
    bnc_free(bnc);
  }
}

void bgp_unlink_nexthop(struct bgp_path_info *path)
{
  struct bgp_nexthop_cache *bnc = path->nexthop;

  bgp_mplsvpn_path_nh_label_unlink(path);

  if (!bnc)
    return;

  path_nh_map(path, NULL, false);

  bgp_unlink_nexthop_check(bnc);
}

void bgp_replace_nexthop_by_peer(struct peer *from, struct peer *to)
{
  struct prefix pp;
  struct prefix pt;
  struct bgp_nexthop_cache *bncp, *bnct;
  afi_t afi;
  ifindex_t ifindex = 0;

  if (!sockunion2hostprefix(&from->su, &pp))
    return;

  /*
   * Gather the ifindex for if up/down events to be
   * tagged into this fun
   */
  if (from->conf_if && IN6_IS_ADDR_LINKLOCAL(&from->su.sin6.sin6_addr))
    ifindex = from->su.sin6.sin6_scope_id;

  afi = family2afi(pp.family);
  bncp = bnc_find(&from->bgp->nexthop_cache_table[afi], &pp, 0, ifindex);

  if (!sockunion2hostprefix(&to->su, &pt))
    return;

  /*
   * Gather the ifindex for if up/down events to be
   * tagged into this fun
   */
  ifindex = 0;
  if (to->conf_if && IN6_IS_ADDR_LINKLOCAL(&to->su.sin6.sin6_addr))
    ifindex = to->su.sin6.sin6_scope_id;
  bnct = bnc_find(&to->bgp->nexthop_cache_table[afi], &pt, 0, ifindex);

  if (bnct != bncp)
    return;

  if (bnct)
    bnct->nht_info = to;
}

/*
 * Returns the bnc whose bnc->nht_info matches the LL peer by
 * looping through the IPv6 nexthop table
 */
static struct bgp_nexthop_cache *
bgp_find_ipv6_nexthop_matching_peer(struct peer *peer)
{
  struct bgp_nexthop_cache *bnc;

  frr_each (bgp_nexthop_cache, &peer->bgp->nexthop_cache_table[AFI_IP6],
      bnc) {
    if (bnc->nht_info == peer) {
      if (BGP_DEBUG(nht, NHT)) {
        zlog_debug(
          "Found bnc: %pFX(%u)(%u)(%p) for peer: %s(%s) %p",
          &bnc->prefix, bnc->ifindex,
          bnc->srte_color, bnc, peer->host,
          peer->bgp->name_pretty, peer);
      }
      return bnc;
    }
  }

  if (BGP_DEBUG(nht, NHT))
    zlog_debug(
      "Could not find bnc for peer %s(%s) %p in v6 nexthop table",
      peer->host, peer->bgp->name_pretty, peer);

  return NULL;
}

void bgp_unlink_nexthop_by_peer(struct peer *peer)
{
  struct prefix p;
  struct bgp_nexthop_cache *bnc;
  afi_t afi = family2afi(peer->su.sa.sa_family);
  ifindex_t ifindex = 0;

  if (!sockunion2hostprefix(&peer->su, &p)) {
    /*
     * In scenarios where unnumbered BGP session is brought
     * down by shutting down the interface before unconfiguring
     * the BGP neighbor, neighbor information in peer->su.sa
     * will be cleared when the interface is shutdown. So
     * during the deletion of unnumbered bgp peer, above check
     * will return true. Therefore, in this case,BGP needs to
     * find the bnc whose bnc->nht_info matches the
     * peer being deleted and free it.
     */
    bnc = bgp_find_ipv6_nexthop_matching_peer(peer);
  } else {
    /*
     * Gather the ifindex for if up/down events to be
     * tagged into this fun
     */
    if (afi == AFI_IP6 &&
        IN6_IS_ADDR_LINKLOCAL(&peer->su.sin6.sin6_addr))
      ifindex = peer->su.sin6.sin6_scope_id;
    bnc = bnc_find(&peer->bgp->nexthop_cache_table[afi], &p, 0,
             ifindex);
  }

  if (!bnc)
    return;

  /* cleanup the peer reference */
  bnc->nht_info = NULL;

  bgp_unlink_nexthop_check(bnc);
}

/*
 * A route and its nexthop might belong to different VRFs. Therefore,
 * we need both the bgp_route and bgp_nexthop pointers.
 */
int bgp_find_or_add_nexthop(struct bgp *bgp_route, struct bgp *bgp_nexthop,
          afi_t afi, safi_t safi, struct bgp_path_info *pi,
          struct peer *peer, int connected,
          const struct prefix *orig_prefix)
{
  struct bgp_nexthop_cache_head *tree = NULL;
  struct bgp_nexthop_cache *bnc;
  struct bgp_path_info *bpi_ultimate;
  struct prefix p;
  uint32_t srte_color = 0;
  int is_bgp_static_route = 0;
  ifindex_t ifindex = 0;

  if (pi) {
    is_bgp_static_route = ((pi->type == ZEBRA_ROUTE_BGP)
               && (pi->sub_type == BGP_ROUTE_STATIC))
                ? 1
                : 0;

    /* Since Extended Next-hop Encoding (RFC5549) support, we want
       to derive
       address-family from the next-hop. */
    if (!is_bgp_static_route)
      afi = BGP_ATTR_MP_NEXTHOP_LEN_IP6(pi->attr) ? AFI_IP6
                    : AFI_IP;

    /* Validation for the ipv4 mapped ipv6 nexthop. */
    if (IS_MAPPED_IPV6(&pi->attr->mp_nexthop_global)) {
      afi = AFI_IP;
    }

    /* This will return true if the global IPv6 NH is a link local
     * addr */
    if (make_prefix(afi, pi, &p) < 0)
      return 1;

    if (!is_bgp_static_route && orig_prefix
        && prefix_same(&p, orig_prefix)) {
      if (BGP_DEBUG(nht, NHT)) {
        zlog_debug(
          "%s(%pFX): prefix loops through itself",
          __func__, &p);
      }
      return 0;
    }

    srte_color = pi->attr->srte_color;
  } else if (peer) {
    /*
     * Gather the ifindex for if up/down events to be
     * tagged into this fun
     */
    if (afi == AFI_IP6 && peer->conf_if &&
        IN6_IS_ADDR_LINKLOCAL(&peer->su.sin6.sin6_addr)) {
      ifindex = peer->su.sin6.sin6_scope_id;
      if (ifindex == 0) {
        if (BGP_DEBUG(nht, NHT)) {
          zlog_debug(
            "%s: Unable to locate ifindex, waiting till we have one",
            peer->conf_if);
        }
        return 0;
      }
    }

    if (!sockunion2hostprefix(&peer->su, &p)) {
      if (BGP_DEBUG(nht, NHT)) {
        zlog_debug(
          "%s: Attempting to register with unknown AFI %d (not %d or %d)",
          __func__, afi, AFI_IP, AFI_IP6);
      }
      return 0;
    }
  } else
    return 0;

  if (is_bgp_static_route)
    tree = &bgp_nexthop->import_check_table[afi];
  else
    tree = &bgp_nexthop->nexthop_cache_table[afi];

  bnc = bnc_find(tree, &p, srte_color, ifindex);
  if (!bnc) {
    bnc = bnc_new(tree, &p, srte_color, ifindex);
    bnc->bgp = bgp_nexthop;
    if (BGP_DEBUG(nht, NHT))
      zlog_debug("Allocated bnc %pFX(%d)(%u)(%s) peer %p",
           &bnc->prefix, bnc->ifindex, bnc->srte_color,
           bnc->bgp->name_pretty, peer);
  } else {
    if (BGP_DEBUG(nht, NHT))
      zlog_debug(
        "Found existing bnc %pFX(%d)(%s) flags 0x%x ifindex %d #paths %d peer %p",
        &bnc->prefix, bnc->ifindex,
        bnc->bgp->name_pretty, bnc->flags, bnc->ifindex,
        bnc->path_count, bnc->nht_info);
  }

  if (pi && is_route_parent_evpn(pi))
    bnc->is_evpn_gwip_nexthop = true;

  if (is_bgp_static_route) {
    SET_FLAG(bnc->flags, BGP_STATIC_ROUTE);

    /* If we're toggling the type, re-register */
    if ((CHECK_FLAG(bgp_route->flags, BGP_FLAG_IMPORT_CHECK))
        && !CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH)) {
      SET_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH);
      UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
      UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
    } else if ((!CHECK_FLAG(bgp_route->flags,
          BGP_FLAG_IMPORT_CHECK))
         && CHECK_FLAG(bnc->flags,
           BGP_STATIC_ROUTE_EXACT_MATCH)) {
      UNSET_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH);
      UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
      UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
    }
  }
  /* When nexthop is already known, but now requires 'connected'
   * resolution,
   * re-register it. The reverse scenario where the nexthop currently
   * requires
   * 'connected' resolution does not need a re-register (i.e., we treat
   * 'connected-required' as an override) except in the scenario where
   * this
   * is actually a case of tracking a peer for connectivity (e.g., after
   * disable connected-check).
   * NOTE: We don't track the number of paths separately for 'connected-
   * required' vs 'connected-not-required' as this change is not a common
   * scenario.
   */
  else if (connected && !CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED)) {
    SET_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED);
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
  } else if (peer && !connected
       && CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED)) {
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED);
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
  }
  if (peer && (bnc->ifindex != ifindex)) {
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
    bnc->ifindex = ifindex;
  }
  if (bgp_route->inst_type == BGP_INSTANCE_TYPE_VIEW) {
    SET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
    SET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
  } else if (!CHECK_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED)
       && !is_default_host_route(&bnc->prefix))
    register_zebra_rnh(bnc);

  if (pi && pi->nexthop != bnc) {
    /* Unlink from existing nexthop cache, if any. This will also
     * free
     * the nexthop cache entry, if appropriate.
     */
    bgp_unlink_nexthop(pi);

    /* updates NHT pi list reference */
    path_nh_map(pi, bnc, true);

    bpi_ultimate = bgp_get_imported_bpi_ultimate(pi);
    if (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_VALID) && bnc->metric)
      (bgp_path_info_extra_get(bpi_ultimate))->igpmetric =
        bnc->metric;
    else if (bpi_ultimate->extra)
      bpi_ultimate->extra->igpmetric = 0;
  } else if (peer) {
    /*
     * Let's not accidentally save the peer data for a peer
     * we are going to throw away in a second or so.
     * When we come back around we'll fix up this
     * data properly in replace_nexthop_by_peer
     */
    if (CHECK_FLAG(peer->flags, PEER_FLAG_CONFIG_NODE))
      bnc->nht_info = (void *)peer; /* NHT peer reference */
  }

  /*
   * We are cheating here.  Views have no associated underlying
   * ability to detect nexthops.  So when we have a view
   * just tell everyone the nexthop is valid
   */
  if (bgp_route->inst_type == BGP_INSTANCE_TYPE_VIEW)
    return 1;
  else if (safi == SAFI_UNICAST && pi &&
     pi->sub_type == BGP_ROUTE_IMPORTED && pi->extra &&
     pi->extra->num_labels && !bnc->is_evpn_gwip_nexthop)
    return bgp_isvalid_nexthop_for_mpls(bnc, pi);
  else
    return (bgp_isvalid_nexthop(bnc));
}

void bgp_delete_connected_nexthop(afi_t afi, struct peer *peer)
{
  struct bgp_nexthop_cache *bnc;
  struct prefix p;
  ifindex_t ifindex = 0;

  if (!peer)
    return;

  /*
   * In case the below check evaluates true and if
   * the bnc has not been freed at this point, then
   * we might have to do something similar to what's
   * done in bgp_unlink_nexthop_by_peer(). Since
   * bgp_unlink_nexthop_by_peer() loops through the
   * nodes of V6 nexthop cache to find the bnc, it is
   * currently not being called here.
   */
  if (!sockunion2hostprefix(&peer->su, &p))
    return;
  /*
   * Gather the ifindex for if up/down events to be
   * tagged into this fun
   */
  if (afi == AFI_IP6 && IN6_IS_ADDR_LINKLOCAL(&peer->su.sin6.sin6_addr))
    ifindex = peer->su.sin6.sin6_scope_id;
  bnc = bnc_find(&peer->bgp->nexthop_cache_table[family2afi(p.family)],
           &p, 0, ifindex);
  if (!bnc) {
    if (BGP_DEBUG(nht, NHT))
      zlog_debug(
        "Cannot find connected NHT node for peer %s(%s)",
        peer->host, peer->bgp->name_pretty);
    return;
  }

  if (bnc->nht_info != peer) {
    if (BGP_DEBUG(nht, NHT))
      zlog_debug(
        "Connected NHT %p node for peer %s(%s) points to %p",
        bnc, peer->host, bnc->bgp->name_pretty,
        bnc->nht_info);
    return;
  }

  bnc->nht_info = NULL;

  if (LIST_EMPTY(&(bnc->paths))) {
    if (BGP_DEBUG(nht, NHT))
      zlog_debug(
        "Freeing connected NHT node %p for peer %s(%s)",
        bnc, peer->host, bnc->bgp->name_pretty);
    unregister_zebra_rnh(bnc);
    bnc_free(bnc);
  }
}

static void bgp_process_nexthop_update(struct bgp_nexthop_cache *bnc,
               struct zapi_route *nhr,
               bool import_check)
{
  struct nexthop *nexthop;
  struct nexthop *oldnh;
  struct nexthop *nhlist_head = NULL;
  struct nexthop *nhlist_tail = NULL;
  int i;
  bool evpn_resolved = false;

  bnc->last_update = monotime(NULL);
  bnc->change_flags = 0;

  /* debug print the input */
  if (BGP_DEBUG(nht, NHT)) {
    char bnc_buf[BNC_FLAG_DUMP_SIZE];

    zlog_debug(
      "%s(%u): Rcvd NH update %pFX(%u)(%u) - metric %d/%d #nhops %d/%d flags %s",
      bnc->bgp->name_pretty, bnc->bgp->vrf_id, &nhr->prefix,
      bnc->ifindex, bnc->srte_color, nhr->metric, bnc->metric,
      nhr->nexthop_num, bnc->nexthop_num,
      bgp_nexthop_dump_bnc_flags(bnc, bnc_buf,
               sizeof(bnc_buf)));
  }

  if (nhr->metric != bnc->metric)
    bnc->change_flags |= BGP_NEXTHOP_METRIC_CHANGED;

  if (nhr->nexthop_num != bnc->nexthop_num)
    bnc->change_flags |= BGP_NEXTHOP_CHANGED;

  if (import_check && (nhr->type == ZEBRA_ROUTE_BGP ||
           !prefix_same(&bnc->prefix, &nhr->prefix))) {
    SET_FLAG(bnc->change_flags, BGP_NEXTHOP_CHANGED);
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_LABELED_VALID);
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_EVPN_INCOMPLETE);

    bnc_nexthop_free(bnc);
    bnc->nexthop = NULL;

    if (BGP_DEBUG(nht, NHT))
      zlog_debug(
        "%s: Import Check does not resolve to the same prefix for %pFX received %pFX or matching route is BGP",
        __func__, &bnc->prefix, &nhr->prefix);
  } else if (nhr->nexthop_num) {
    struct peer *peer = bnc->nht_info;

    /* notify bgp fsm if nbr ip goes from invalid->valid */
    if (!bnc->nexthop_num)
      UNSET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);

    if (!bnc->is_evpn_gwip_nexthop)
      bnc->flags |= BGP_NEXTHOP_VALID;
    bnc->metric = nhr->metric;
    bnc->nexthop_num = nhr->nexthop_num;

    bnc->flags &= ~BGP_NEXTHOP_LABELED_VALID; /* check below */

    for (i = 0; i < nhr->nexthop_num; i++) {
      int num_labels = 0;

      nexthop = nexthop_from_zapi_nexthop(&nhr->nexthops[i]);

      /*
       * Turn on RA for the v6 nexthops
       * we receive from bgp.  This is to allow us
       * to work with v4 routing over v6 nexthops
       */
      if (peer && !peer->ifp
          && CHECK_FLAG(peer->flags,
            PEER_FLAG_CAPABILITY_ENHE)
          && nhr->prefix.family == AF_INET6
          && nexthop->type != NEXTHOP_TYPE_BLACKHOLE) {
        struct interface *ifp;

        ifp = if_lookup_by_index(nexthop->ifindex,
               nexthop->vrf_id);
        if (ifp)
          zclient_send_interface_radv_req(
            zclient, nexthop->vrf_id, ifp,
            true,
            BGP_UNNUM_DEFAULT_RA_INTERVAL);
      }
      /* There is at least one label-switched path */
      if (nexthop->nh_label &&
        nexthop->nh_label->num_labels) {

        bnc->flags |= BGP_NEXTHOP_LABELED_VALID;
        num_labels = nexthop->nh_label->num_labels;
      }

      if (BGP_DEBUG(nht, NHT)) {
        char buf[NEXTHOP_STRLEN];
        zlog_debug(
          "    nhop via %s (%d labels)",
          nexthop2str(nexthop, buf, sizeof(buf)),
          num_labels);
      }

      if (nhlist_tail) {
        nhlist_tail->next = nexthop;
        nhlist_tail = nexthop;
      } else {
        nhlist_tail = nexthop;
        nhlist_head = nexthop;
      }

      /* No need to evaluate the nexthop if we have already
       * determined
       * that there has been a change.
       */
      if (bnc->change_flags & BGP_NEXTHOP_CHANGED)
        continue;

      for (oldnh = bnc->nexthop; oldnh; oldnh = oldnh->next)
        if (nexthop_same(oldnh, nexthop))
          break;

      if (!oldnh)
        bnc->change_flags |= BGP_NEXTHOP_CHANGED;
    }
    bnc_nexthop_free(bnc);
    bnc->nexthop = nhlist_head;

    /*
     * Gateway IP nexthop is L3 reachable. Mark it as
     * BGP_NEXTHOP_VALID only if it is recursively resolved with a
     * remote EVPN RT-2.
     * Else, mark it as BGP_NEXTHOP_EVPN_INCOMPLETE.
     * When its mapping with EVPN RT-2 is established, unset
     * BGP_NEXTHOP_EVPN_INCOMPLETE and set BGP_NEXTHOP_VALID.
     */
    if (bnc->is_evpn_gwip_nexthop) {
      evpn_resolved = bgp_evpn_is_gateway_ip_resolved(bnc);

      if (BGP_DEBUG(nht, NHT))
        zlog_debug(
          "EVPN gateway IP %pFX recursive MAC/IP lookup %s",
          &bnc->prefix,
          (evpn_resolved ? "successful"
                   : "failed"));

      if (evpn_resolved) {
        bnc->flags |= BGP_NEXTHOP_VALID;
        bnc->flags &= ~BGP_NEXTHOP_EVPN_INCOMPLETE;
        bnc->change_flags |= BGP_NEXTHOP_MACIP_CHANGED;
      } else {
        bnc->flags |= BGP_NEXTHOP_EVPN_INCOMPLETE;
        bnc->flags &= ~BGP_NEXTHOP_VALID;
      }
    }
  } else {
    bnc->flags &= ~BGP_NEXTHOP_EVPN_INCOMPLETE;
    bnc->flags &= ~BGP_NEXTHOP_VALID;
    bnc->flags &= ~BGP_NEXTHOP_LABELED_VALID;
    bnc->nexthop_num = nhr->nexthop_num;

    /* notify bgp fsm if nbr ip goes from valid->invalid */
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);

    bnc_nexthop_free(bnc);
    bnc->nexthop = NULL;
  }

  evaluate_paths(bnc);
}

static void bgp_nht_ifp_table_handle(struct bgp *bgp,
             struct bgp_nexthop_cache_head *table,
             struct interface *ifp, bool up)
{
  struct bgp_nexthop_cache *bnc;

  frr_each (bgp_nexthop_cache, table, bnc) {
    if (bnc->ifindex != ifp->ifindex)
      continue;

    bnc->last_update = monotime(NULL);
    bnc->change_flags = 0;

    /*
     * For interface based routes ( ala the v6 LL routes
     * that this was written for ) the metric received
     * for the connected route is 0 not 1.
     */
    bnc->metric = 0;
    if (up) {
      SET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
      SET_FLAG(bnc->change_flags, BGP_NEXTHOP_CHANGED);
      bnc->nexthop_num = 1;
    } else {
      UNSET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);
      UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
      SET_FLAG(bnc->change_flags, BGP_NEXTHOP_CHANGED);
      bnc->nexthop_num = 0;
    }

    evaluate_paths(bnc);
  }
}
static void bgp_nht_ifp_handle(struct interface *ifp, bool up)
{
  struct bgp *bgp;

  bgp = ifp->vrf->info;
  if (!bgp)
    return;

  bgp_nht_ifp_table_handle(bgp, &bgp->nexthop_cache_table[AFI_IP], ifp,
         up);
  bgp_nht_ifp_table_handle(bgp, &bgp->import_check_table[AFI_IP], ifp,
         up);
  bgp_nht_ifp_table_handle(bgp, &bgp->nexthop_cache_table[AFI_IP6], ifp,
         up);
  bgp_nht_ifp_table_handle(bgp, &bgp->import_check_table[AFI_IP6], ifp,
         up);
}

void bgp_nht_ifp_up(struct interface *ifp)
{
  bgp_nht_ifp_handle(ifp, true);
}

void bgp_nht_ifp_down(struct interface *ifp)
{
  bgp_nht_ifp_handle(ifp, false);
}

static void bgp_nht_ifp_initial(struct event *thread)
{
  ifindex_t ifindex = EVENT_VAL(thread);
  struct bgp *bgp = EVENT_ARG(thread);
  struct interface *ifp = if_lookup_by_index(ifindex, bgp->vrf_id);

  if (!ifp)
    return;

  if (BGP_DEBUG(nht, NHT))
    zlog_debug(
      "Handle NHT initial update for Intf %s(%d) status %s",
      ifp->name, ifp->ifindex, if_is_up(ifp) ? "up" : "down");

  if (if_is_up(ifp))
    bgp_nht_ifp_up(ifp);
  else
    bgp_nht_ifp_down(ifp);
}

/*
 * So the bnc code has the ability to handle interface up/down
 * events to properly handle v6 LL peering.
 * What is happening here:
 * The event system for peering expects the nht code to
 * report on the tracking events after we move to active
 * So let's give the system a chance to report on that event
 * in a manner that is expected.
 */
void bgp_nht_interface_events(struct peer *peer)
{
  struct bgp *bgp = peer->bgp;
  struct bgp_nexthop_cache_head *table;
  struct bgp_nexthop_cache *bnc;
  struct prefix p;
  ifindex_t ifindex = 0;

  if (!IN6_IS_ADDR_LINKLOCAL(&peer->su.sin6.sin6_addr))
    return;

  if (!sockunion2hostprefix(&peer->su, &p))
    return;
  /*
   * Gather the ifindex for if up/down events to be
   * tagged into this fun
   */
  if (peer->conf_if && IN6_IS_ADDR_LINKLOCAL(&peer->su.sin6.sin6_addr))
    ifindex = peer->su.sin6.sin6_scope_id;

  table = &bgp->nexthop_cache_table[AFI_IP6];
  bnc = bnc_find(table, &p, 0, ifindex);
  if (!bnc)
    return;

  if (bnc->ifindex)
    event_add_event(bm->master, bgp_nht_ifp_initial, bnc->bgp,
        bnc->ifindex, NULL);
}

void bgp_parse_nexthop_update(int command, vrf_id_t vrf_id)
{
  struct bgp_nexthop_cache_head *tree = NULL;
  struct bgp_nexthop_cache *bnc_nhc, *bnc_import;
  struct bgp *bgp;
  struct prefix match;
  struct zapi_route nhr;
  afi_t afi;

  bgp = bgp_lookup_by_vrf_id(vrf_id);
  if (!bgp) {
    flog_err(
      EC_BGP_NH_UPD,
      "parse nexthop update: instance not found for vrf_id %u",
      vrf_id);
    return;
  }

  if (!zapi_nexthop_update_decode(zclient->ibuf, &match, &nhr)) {
    zlog_err("%s[%s]: Failure to decode nexthop update", __func__,
       bgp->name_pretty);
    return;
  }

  afi = family2afi(match.family);
  tree = &bgp->nexthop_cache_table[afi];

  bnc_nhc = bnc_find(tree, &match, nhr.srte_color, 0);
  if (!bnc_nhc) {
    if (BGP_DEBUG(nht, NHT))
      zlog_debug(
        "parse nexthop update %pFX(%u)(%s): bnc info not found for nexthop cache",
        &nhr.prefix, nhr.srte_color, bgp->name_pretty);
  } else
    bgp_process_nexthop_update(bnc_nhc, &nhr, false);

  tree = &bgp->import_check_table[afi];

  bnc_import = bnc_find(tree, &match, nhr.srte_color, 0);
  if (!bnc_import) {
    if (BGP_DEBUG(nht, NHT))
      zlog_debug(
        "parse nexthop update %pFX(%u)(%s): bnc info not found for import check",
        &nhr.prefix, nhr.srte_color, bgp->name_pretty);
  } else
    bgp_process_nexthop_update(bnc_import, &nhr, true);

  /*
   * HACK: if any BGP route is dependant on an SR-policy that doesn't
   * exist, zebra will never send NH updates relative to that policy. In
   * that case, whenever we receive an update about a colorless NH, update
   * the corresponding colorful NHs that share the same endpoint but that
   * are inactive. This ugly hack should work around the problem at the
   * cost of a performance pernalty. Long term, what should be done is to
   * make zebra's RNH subsystem aware of SR-TE colors (like bgpd is),
   * which should provide a better infrastructure to solve this issue in
   * a more efficient and elegant way.
   */
  if (nhr.srte_color == 0 && bnc_nhc) {
    struct bgp_nexthop_cache *bnc_iter;

    frr_each (bgp_nexthop_cache, &bgp->nexthop_cache_table[afi],
        bnc_iter) {
      if (!prefix_same(&bnc_nhc->prefix, &bnc_iter->prefix) ||
          bnc_iter->srte_color == 0 ||
          CHECK_FLAG(bnc_iter->flags, BGP_NEXTHOP_VALID))
        continue;

      bgp_process_nexthop_update(bnc_iter, &nhr, false);
    }
  }
}

/*
 * Cleanup nexthop registration and status information for BGP nexthops
 * pertaining to this VRF. This is invoked upon VRF deletion.
 */
void bgp_cleanup_nexthops(struct bgp *bgp)
{
  for (afi_t afi = AFI_IP; afi < AFI_MAX; afi++) {
    struct bgp_nexthop_cache *bnc;

    frr_each (bgp_nexthop_cache, &bgp->nexthop_cache_table[afi],
        bnc) {
      /* Clear relevant flags. */
      UNSET_FLAG(bnc->flags, BGP_NEXTHOP_VALID);
      UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
      UNSET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);
      UNSET_FLAG(bnc->flags, BGP_NEXTHOP_EVPN_INCOMPLETE);
    }
  }
}

/**
 * make_prefix - make a prefix structure from the path (essentially
 * path's node.
 */
static int make_prefix(int afi, struct bgp_path_info *pi, struct prefix *p)
{

  int is_bgp_static = ((pi->type == ZEBRA_ROUTE_BGP)
           && (pi->sub_type == BGP_ROUTE_STATIC))
            ? 1
            : 0;
  struct bgp_dest *net = pi->net;
  const struct prefix *p_orig = bgp_dest_get_prefix(net);
  struct in_addr ipv4;

  if (p_orig->family == AF_FLOWSPEC) {
    if (!pi->peer)
      return -1;
    return bgp_flowspec_get_first_nh(pi->peer->bgp,
             pi, p, afi);
  }
  memset(p, 0, sizeof(struct prefix));
  switch (afi) {
  case AFI_IP:
    p->family = AF_INET;
    if (is_bgp_static) {
      p->u.prefix4 = p_orig->u.prefix4;
      p->prefixlen = p_orig->prefixlen;
    } else {
      if (IS_MAPPED_IPV6(&pi->attr->mp_nexthop_global)) {
        ipv4_mapped_ipv6_to_ipv4(
          &pi->attr->mp_nexthop_global, &ipv4);
        p->u.prefix4 = ipv4;
        p->prefixlen = IPV4_MAX_BITLEN;
      } else {
        if (p_orig->family == AF_EVPN)
          p->u.prefix4 =
            pi->attr->mp_nexthop_global_in;
        else
          p->u.prefix4 = pi->attr->nexthop;
        p->prefixlen = IPV4_MAX_BITLEN;
      }
    }
    break;
  case AFI_IP6:
    p->family = AF_INET6;

    if (is_bgp_static) {
      p->u.prefix6 = p_orig->u.prefix6;
      p->prefixlen = p_orig->prefixlen;
    } else {
      /* If we receive MP_REACH nexthop with ::(LL)
       * or LL(LL), use LL address as nexthop cache.
       */
      if (pi->attr->mp_nexthop_len
            == BGP_ATTR_NHLEN_IPV6_GLOBAL_AND_LL
          && (IN6_IS_ADDR_UNSPECIFIED(
          &pi->attr->mp_nexthop_global)
        || IN6_IS_ADDR_LINKLOCAL(
          &pi->attr->mp_nexthop_global)))
        p->u.prefix6 = pi->attr->mp_nexthop_local;
      /* If we receive MR_REACH with (GA)::(LL)
       * then check for route-map to choose GA or LL
       */
      else if (pi->attr->mp_nexthop_len
         == BGP_ATTR_NHLEN_IPV6_GLOBAL_AND_LL) {
        if (pi->attr->mp_nexthop_prefer_global)
          p->u.prefix6 =
            pi->attr->mp_nexthop_global;
        else
          p->u.prefix6 =
            pi->attr->mp_nexthop_local;
      } else
        p->u.prefix6 = pi->attr->mp_nexthop_global;
      p->prefixlen = IPV6_MAX_BITLEN;
    }
    break;
  default:
    if (BGP_DEBUG(nht, NHT)) {
      zlog_debug(
        "%s: Attempting to make prefix with unknown AFI %d (not %d or %d)",
        __func__, afi, AFI_IP, AFI_IP6);
    }
    break;
  }
  return 0;
}

/**
 * sendmsg_zebra_rnh -- Format and send a nexthop register/Unregister
 *   command to Zebra.
 * ARGUMENTS:
 *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
 *   int command -- command to send to zebra
 * RETURNS:
 *   void.
 */
static void sendmsg_zebra_rnh(struct bgp_nexthop_cache *bnc, int command)
{
  bool exact_match = false;
  bool resolve_via_default = false;
  int ret;

  if (!zclient)
    return;

  /* Don't try to register if Zebra doesn't know of this instance. */
  if (!IS_BGP_INST_KNOWN_TO_ZEBRA(bnc->bgp)) {
    if (BGP_DEBUG(zebra, ZEBRA))
      zlog_debug(
        "%s: No zebra instance to talk to, not installing NHT entry",
        __func__);
    return;
  }

  if (!bgp_zebra_num_connects()) {
    if (BGP_DEBUG(zebra, ZEBRA))
      zlog_debug(
        "%s: We have not connected yet, cannot send nexthops",
        __func__);
  }
  if (command == ZEBRA_NEXTHOP_REGISTER) {
    if (CHECK_FLAG(bnc->flags, BGP_NEXTHOP_CONNECTED))
      exact_match = true;
    if (CHECK_FLAG(bnc->flags, BGP_STATIC_ROUTE_EXACT_MATCH))
      resolve_via_default = true;
  }

  if (BGP_DEBUG(zebra, ZEBRA))
    zlog_debug("%s: sending cmd %s for %pFX (vrf %s)", __func__,
         zserv_command_string(command), &bnc->prefix,
         bnc->bgp->name_pretty);

  ret = zclient_send_rnh(zclient, command, &bnc->prefix, SAFI_UNICAST,
             exact_match, resolve_via_default,
             bnc->bgp->vrf_id);
  if (ret == ZCLIENT_SEND_FAILURE) {
    flog_warn(EC_BGP_ZEBRA_SEND,
        "sendmsg_nexthop: zclient_send_message() failed");
    return;
  }

  if (command == ZEBRA_NEXTHOP_REGISTER)
    SET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
  else if (command == ZEBRA_NEXTHOP_UNREGISTER)
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
  return;
}

/**
 * register_zebra_rnh - register a NH/route with Zebra for notification
 *    when the route or the route to the nexthop changes.
 * ARGUMENTS:
 *   struct bgp_nexthop_cache *bnc
 * RETURNS:
 *   void.
 */
static void register_zebra_rnh(struct bgp_nexthop_cache *bnc)
{
  /* Check if we have already registered */
  if (bnc->flags & BGP_NEXTHOP_REGISTERED)
    return;

  if (bnc->ifindex) {
    SET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
    return;
  }

  sendmsg_zebra_rnh(bnc, ZEBRA_NEXTHOP_REGISTER);
}

/**
 * unregister_zebra_rnh -- Unregister the route/nexthop from Zebra.
 * ARGUMENTS:
 *   struct bgp_nexthop_cache *bnc
 * RETURNS:
 *   void.
 */
static void unregister_zebra_rnh(struct bgp_nexthop_cache *bnc)
{
  /* Check if we have already registered */
  if (!CHECK_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED))
    return;

  if (bnc->ifindex) {
    UNSET_FLAG(bnc->flags, BGP_NEXTHOP_REGISTERED);
    return;
  }

  sendmsg_zebra_rnh(bnc, ZEBRA_NEXTHOP_UNREGISTER);
}

/**
 * evaluate_paths - Evaluate the paths/nets associated with a nexthop.
 * ARGUMENTS:
 *   struct bgp_nexthop_cache *bnc -- the nexthop structure.
 * RETURNS:
 *   void.
 */
void evaluate_paths(struct bgp_nexthop_cache *bnc)
{
  struct bgp_dest *dest;
  struct bgp_path_info *path;
  struct bgp_path_info *bpi_ultimate;
  int afi;
  struct peer *peer = (struct peer *)bnc->nht_info;
  struct bgp_table *table;
  safi_t safi;
  struct bgp *bgp_path;
  const struct prefix *p;

  if (BGP_DEBUG(nht, NHT)) {
    char bnc_buf[BNC_FLAG_DUMP_SIZE];
    char chg_buf[BNC_FLAG_DUMP_SIZE];

    zlog_debug(
      "NH update for %pFX(%d)(%u)(%s) - flags %s chgflags %s- evaluate paths",
      &bnc->prefix, bnc->ifindex, bnc->srte_color,
      bnc->bgp->name_pretty,
      bgp_nexthop_dump_bnc_flags(bnc, bnc_buf,
               sizeof(bnc_buf)),
      bgp_nexthop_dump_bnc_change_flags(bnc, chg_buf,
                sizeof(bnc_buf)));
  }

  LIST_FOREACH (path, &(bnc->paths), nh_thread) {
    if (path->type == ZEBRA_ROUTE_BGP &&
        (path->sub_type == BGP_ROUTE_NORMAL ||
         path->sub_type == BGP_ROUTE_STATIC ||
         path->sub_type == BGP_ROUTE_IMPORTED))
      /* evaluate the path */
      ;
    else if (path->sub_type == BGP_ROUTE_REDISTRIBUTE) {
      /* evaluate the path for redistributed routes
       * except those from VNC
       */
      if ((path->type == ZEBRA_ROUTE_VNC) ||
          (path->type == ZEBRA_ROUTE_VNC_DIRECT))
        continue;
    } else
      /* don't evaluate the path */
      continue;

    dest = path->net;
    assert(dest && bgp_dest_table(dest));
    p = bgp_dest_get_prefix(dest);
    afi = family2afi(p->family);
    table = bgp_dest_table(dest);
    safi = table->safi;

    /*
     * handle routes from other VRFs (they can have a
     * nexthop in THIS VRF). bgp_path is the bgp instance
     * that owns the route referencing this nexthop.
     */
    bgp_path = table->bgp;

    /*
     * Path becomes valid/invalid depending on whether the nexthop
     * reachable/unreachable.
     *
     * In case of unicast routes that were imported from vpn
     * and that have labels, they are valid only if there are
     * nexthops with labels
     *
     * If the nexthop is EVPN gateway-IP,
     * do not check for a valid label.
     */

    bool bnc_is_valid_nexthop = false;
    bool path_valid = false;

    if (safi == SAFI_UNICAST && path->sub_type == BGP_ROUTE_IMPORTED
        && path->extra && path->extra->num_labels
        && (path->attr->evpn_overlay.type
      != OVERLAY_INDEX_GATEWAY_IP)) {
      bnc_is_valid_nexthop =
        bgp_isvalid_nexthop_for_mpls(bnc, path) ? true
                  : false;
    } else {
      if (bgp_update_martian_nexthop(
            bnc->bgp, afi, safi, path->type,
            path->sub_type, path->attr, dest)) {
        if (BGP_DEBUG(nht, NHT))
          zlog_debug(
            "%s: prefix %pBD (vrf %s), ignoring path due to martian or self-next-hop",
            __func__, dest, bgp_path->name);
      } else
        bnc_is_valid_nexthop =
          bgp_isvalid_nexthop(bnc) ? true : false;
    }

    if (BGP_DEBUG(nht, NHT)) {

      if (dest->pdest) {
        char rd_buf[RD_ADDRSTRLEN];

        prefix_rd2str(
          (struct prefix_rd *)bgp_dest_get_prefix(
            dest->pdest),
          rd_buf, sizeof(rd_buf),
          bgp_get_asnotation(bnc->bgp));
        zlog_debug(
          "... eval path %d/%d %pBD RD %s %s flags 0x%x",
          afi, safi, dest, rd_buf,
          bgp_path->name_pretty, path->flags);
      } else
        zlog_debug(
          "... eval path %d/%d %pBD %s flags 0x%x",
          afi, safi, dest, bgp_path->name_pretty,
          path->flags);
    }

    /* Skip paths marked for removal or as history. */
    if (CHECK_FLAG(path->flags, BGP_PATH_REMOVED)
        || CHECK_FLAG(path->flags, BGP_PATH_HISTORY))
      continue;

    /* Copy the metric to the path. Will be used for bestpath
     * computation */
    bpi_ultimate = bgp_get_imported_bpi_ultimate(path);
    if (bgp_isvalid_nexthop(bnc) && bnc->metric)
      (bgp_path_info_extra_get(bpi_ultimate))->igpmetric =
        bnc->metric;
    else if (bpi_ultimate->extra)
      bpi_ultimate->extra->igpmetric = 0;

    if (CHECK_FLAG(bnc->change_flags, BGP_NEXTHOP_METRIC_CHANGED)
        || CHECK_FLAG(bnc->change_flags, BGP_NEXTHOP_CHANGED)
        || path->attr->srte_color != 0)
      SET_FLAG(path->flags, BGP_PATH_IGP_CHANGED);

    path_valid = CHECK_FLAG(path->flags, BGP_PATH_VALID);
    if (path->type == ZEBRA_ROUTE_BGP &&
        path->sub_type == BGP_ROUTE_STATIC &&
        !CHECK_FLAG(bgp_path->flags, BGP_FLAG_IMPORT_CHECK))
      /* static routes with 'no bgp network import-check' are
       * always valid. if nht is called with static routes,
       * the vpn exportation needs to be triggered
       */
      vpn_leak_from_vrf_update(bgp_get_default(), bgp_path,
             path);
    else if (path->sub_type == BGP_ROUTE_REDISTRIBUTE &&
       safi == SAFI_UNICAST &&
       (bgp_path->inst_type == BGP_INSTANCE_TYPE_VRF ||
        bgp_path->inst_type == BGP_INSTANCE_TYPE_DEFAULT))
      /* redistribute routes are always valid
       * if nht is called with redistribute routes, the vpn
       * exportation needs to be triggered
       */
      vpn_leak_from_vrf_update(bgp_get_default(), bgp_path,
             path);
    else if (path_valid != bnc_is_valid_nexthop) {
      if (path_valid) {
        /* No longer valid, clear flag; also for EVPN
         * routes, unimport from VRFs if needed.
         */
        bgp_aggregate_decrement(bgp_path, p, path, afi,
              safi);
        bgp_path_info_unset_flag(dest, path,
               BGP_PATH_VALID);
        if (safi == SAFI_EVPN &&
            bgp_evpn_is_prefix_nht_supported(bgp_dest_get_prefix(dest)))
          bgp_evpn_unimport_route(bgp_path,
            afi, safi, bgp_dest_get_prefix(dest), path);
        if (safi == SAFI_UNICAST &&
            (bgp_path->inst_type !=
             BGP_INSTANCE_TYPE_VIEW))
          vpn_leak_from_vrf_withdraw(
            bgp_get_default(), bgp_path,
            path);
      } else {
        /* Path becomes valid, set flag; also for EVPN
         * routes, import from VRFs if needed.
         */
        bgp_path_info_set_flag(dest, path,
                   BGP_PATH_VALID);
        bgp_aggregate_increment(bgp_path, p, path, afi,
              safi);
        if (safi == SAFI_EVPN &&
            bgp_evpn_is_prefix_nht_supported(bgp_dest_get_prefix(dest)))
          bgp_evpn_import_route(bgp_path,
            afi, safi, bgp_dest_get_prefix(dest), path);
        if (safi == SAFI_UNICAST &&
            (bgp_path->inst_type !=
             BGP_INSTANCE_TYPE_VIEW))
          vpn_leak_from_vrf_update(
            bgp_get_default(), bgp_path,
            path);
      }
    }

    bgp_process(bgp_path, dest, afi, safi);
  }

  if (peer) {
    int valid_nexthops = bgp_isvalid_nexthop(bnc);

    if (valid_nexthops) {
      /*
       * Peering cannot occur across a blackhole nexthop
       */
      if (bnc->nexthop_num == 1 && bnc->nexthop
          && bnc->nexthop->type == NEXTHOP_TYPE_BLACKHOLE) {
        peer->last_reset = PEER_DOWN_WAITING_NHT;
        valid_nexthops = 0;
      } else
        peer->last_reset = PEER_DOWN_WAITING_OPEN;
    } else
      peer->last_reset = PEER_DOWN_WAITING_NHT;

    if (!CHECK_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED)) {
      if (BGP_DEBUG(nht, NHT))
        zlog_debug(
          "%s: Updating peer (%s(%s)) status with NHT nexthops %d",
          __func__, peer->host,
          peer->bgp->name_pretty,
          !!valid_nexthops);
      bgp_fsm_nht_update(peer, !!valid_nexthops);
      SET_FLAG(bnc->flags, BGP_NEXTHOP_PEER_NOTIFIED);
    }
  }

  RESET_FLAG(bnc->change_flags);
}

/**
 * path_nh_map - make or break path-to-nexthop association.
 * ARGUMENTS:
 *   path - pointer to the path structure
 *   bnc - pointer to the nexthop structure
 *   make - if set, make the association. if unset, just break the existing
 *          association.
 */
void path_nh_map(struct bgp_path_info *path, struct bgp_nexthop_cache *bnc,
     bool make)
{
  if (path->nexthop) {
    LIST_REMOVE(path, nh_thread);
    path->nexthop->path_count--;
    path->nexthop = NULL;
  }
  if (make) {
    LIST_INSERT_HEAD(&(bnc->paths), path, nh_thread);
    path->nexthop = bnc;
    path->nexthop->path_count++;
  }
}

/*
 * This function is called to register nexthops to zebra
 * as that we may have tried to install the nexthops
 * before we actually have a zebra connection
 */
void bgp_nht_register_nexthops(struct bgp *bgp)
{
  for (afi_t afi = AFI_IP; afi < AFI_MAX; afi++) {
    struct bgp_nexthop_cache *bnc;

    frr_each (bgp_nexthop_cache, &bgp->nexthop_cache_table[afi],
        bnc) {
      register_zebra_rnh(bnc);
    }
  }
}

void bgp_nht_reg_enhe_cap_intfs(struct peer *peer)
{
  struct bgp *bgp;
  struct bgp_nexthop_cache *bnc;
  struct nexthop *nhop;
  struct interface *ifp;
  struct prefix p;
  ifindex_t ifindex = 0;

  if (peer->ifp)
    return;

  bgp = peer->bgp;
  if (!sockunion2hostprefix(&peer->su, &p)) {
    zlog_warn("%s: Unable to convert sockunion to prefix for %s",
        __func__, peer->host);
    return;
  }

  if (p.family != AF_INET6)
    return;
  /*
   * Gather the ifindex for if up/down events to be
   * tagged into this fun
   */
  if (peer->conf_if && IN6_IS_ADDR_LINKLOCAL(&peer->su.sin6.sin6_addr))
    ifindex = peer->su.sin6.sin6_scope_id;

  bnc = bnc_find(&bgp->nexthop_cache_table[AFI_IP6], &p, 0, ifindex);
  if (!bnc)
    return;

  if (peer != bnc->nht_info)
    return;

  for (nhop = bnc->nexthop; nhop; nhop = nhop->next) {
    ifp = if_lookup_by_index(nhop->ifindex, nhop->vrf_id);

    if (!ifp)
      continue;

    zclient_send_interface_radv_req(zclient,
            nhop->vrf_id,
            ifp, true,
            BGP_UNNUM_DEFAULT_RA_INTERVAL);
  }
}

void bgp_nht_dereg_enhe_cap_intfs(struct peer *peer)
{
  struct bgp *bgp;
  struct bgp_nexthop_cache *bnc;
  struct nexthop *nhop;
  struct interface *ifp;
  struct prefix p;
  ifindex_t ifindex = 0;

  if (peer->ifp)
    return;

  bgp = peer->bgp;

  if (!sockunion2hostprefix(&peer->su, &p)) {
    zlog_warn("%s: Unable to convert sockunion to prefix for %s",
        __func__, peer->host);
    return;
  }

  if (p.family != AF_INET6)
    return;
  /*
   * Gather the ifindex for if up/down events to be
   * tagged into this fun
   */
  if (peer->conf_if && IN6_IS_ADDR_LINKLOCAL(&peer->su.sin6.sin6_addr))
    ifindex = peer->su.sin6.sin6_scope_id;

  bnc = bnc_find(&bgp->nexthop_cache_table[AFI_IP6], &p, 0, ifindex);
  if (!bnc)
    return;

  if (peer != bnc->nht_info)
    return;

  for (nhop = bnc->nexthop; nhop; nhop = nhop->next) {
    ifp = if_lookup_by_index(nhop->ifindex, nhop->vrf_id);

    if (!ifp)
      continue;

    zclient_send_interface_radv_req(zclient, nhop->vrf_id, ifp, 0,
            0);
  }
}

/****************************************************************************
 * L3 NHGs are used for fast failover of nexthops in the dplane. These are
 * the APIs for allocating L3 NHG ids. Management of the L3 NHG itself is
 * left to the application using it.
 * PS: Currently EVPN host routes is the only app using L3 NHG for fast
 * failover of remote ES links.
 ***************************************************************************/
static bitfield_t bgp_nh_id_bitmap;
static uint32_t bgp_l3nhg_start;

/* XXX - currently we do nothing on the callbacks */
static void bgp_l3nhg_add_cb(const char *name)
{
}

static void bgp_l3nhg_modify_cb(const struct nexthop_group_cmd *nhgc)
{
}

static void bgp_l3nhg_add_nexthop_cb(const struct nexthop_group_cmd *nhgc,
             const struct nexthop *nhop)
{
}

static void bgp_l3nhg_del_nexthop_cb(const struct nexthop_group_cmd *nhgc,
             const struct nexthop *nhop)
{
}

static void bgp_l3nhg_del_cb(const char *name)
{
}

static void bgp_l3nhg_zebra_init(void)
{
  static bool bgp_l3nhg_zebra_inited;
  if (bgp_l3nhg_zebra_inited)
    return;

  bgp_l3nhg_zebra_inited = true;
  bgp_l3nhg_start = zclient_get_nhg_start(ZEBRA_ROUTE_BGP);
  nexthop_group_init(bgp_l3nhg_add_cb, bgp_l3nhg_modify_cb,
         bgp_l3nhg_add_nexthop_cb, bgp_l3nhg_del_nexthop_cb,
         bgp_l3nhg_del_cb);
}


void bgp_l3nhg_init(void)
{
  uint32_t id_max;

  id_max = MIN(ZEBRA_NHG_PROTO_SPACING - 1, 16 * 1024);
  bf_init(bgp_nh_id_bitmap, id_max);
  bf_assign_zero_index(bgp_nh_id_bitmap);

  if (BGP_DEBUG(nht, NHT) || BGP_DEBUG(evpn_mh, EVPN_MH_ES))
    zlog_debug("bgp l3_nhg range %u - %u", bgp_l3nhg_start + 1,
         bgp_l3nhg_start + id_max);
}

void bgp_l3nhg_finish(void)
{
  bf_free(bgp_nh_id_bitmap);
}

uint32_t bgp_l3nhg_id_alloc(void)
{
  uint32_t nhg_id = 0;

  bgp_l3nhg_zebra_init();
  bf_assign_index(bgp_nh_id_bitmap, nhg_id);
  if (nhg_id)
    nhg_id += bgp_l3nhg_start;

  return nhg_id;
}

void bgp_l3nhg_id_free(uint32_t nhg_id)
{
  if (!nhg_id || (nhg_id <= bgp_l3nhg_start))
    return;

  nhg_id -= bgp_l3nhg_start;

  bf_release_index(bgp_nh_id_bitmap, nhg_id);
}

Coverage Report

Created: 2025-08-28 06:29