From f55c9a46537e4d0de7ead681f095738b5d33d910 Mon Sep 17 00:00:00 2001 From: Soman K S Date: Wed, 8 Apr 2020 15:04:10 +0530 Subject: [PATCH] bgpd: Configuring default-originate withdraws default route Issue: Configuring default-originate when static default route is previously advertised results in withdrawal of the route. Fix : Delete the adj-out entry for the previously advertised static default route without sending explicit withdraw message. Signed-off-by: kssoman --- bgpd/bgp_updgrp_adv.c | 102 +++++++++++++++++++++++++++++++++--------- 1 file changed, 81 insertions(+), 21 deletions(-) diff --git a/bgpd/bgp_updgrp_adv.c b/bgpd/bgp_updgrp_adv.c index e40b3320ea46..6399bc93aa26 100644 --- a/bgpd/bgp_updgrp_adv.c +++ b/bgpd/bgp_updgrp_adv.c @@ -533,6 +533,14 @@ void bgp_adj_out_unset_subgroup(struct bgp_node *rn, if (adj->adv) bgp_advertise_clean_subgroup(subgrp, adj); + /* If default originate is enabled and the route is default + * route, do not send withdraw. This will prevent deletion of + * the default route at the peer. + */ + if (CHECK_FLAG(subgrp->sflags, SUBGRP_STATUS_DEFAULT_ORIGINATE) + && is_default_prefix(&rn->p)) + return; + if (adj->attr && withdraw) { /* We need advertisement structure. */ adj->adv = bgp_advertise_new(); @@ -636,12 +644,25 @@ void subgroup_announce_table(struct update_subgroup *subgrp, rn_p, &attr)) bgp_adj_out_set_subgroup(rn, subgrp, &attr, ri); - else + else { + /* If default originate is enabled for + * the peer, do not send explicit + * withdraw. This will prevent deletion + * of default route advertised through + * default originate + */ + if (CHECK_FLAG( + peer->af_flags[afi][safi], + PEER_FLAG_DEFAULT_ORIGINATE) + && is_default_prefix(&rn->p)) + break; + bgp_adj_out_unset_subgroup( rn, subgrp, 1, bgp_addpath_id_for_peer( peer, afi, safi, &ri->tx_addpath)); + } } } @@ -709,7 +730,9 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw) struct prefix p; struct peer *from; struct bgp_node *rn; + struct bgp_path_info *pi; struct peer *peer; + struct bgp_adj_out *adj; route_map_result_t ret = RMAP_DENYMATCH; afi_t afi; safi_t safi; @@ -732,10 +755,6 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw) attr.local_pref = bgp->default_local_pref; - memset(&p, 0, sizeof(p)); - p.family = afi2family(afi); - p.prefixlen = 0; - if ((afi == AFI_IP6) || peer_cap_enhe(peer, afi, safi)) { /* IPv6 global nexthop must be included. */ attr.mp_nexthop_len = BGP_ATTR_NHLEN_IPV6_GLOBAL; @@ -778,21 +797,40 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw) } } + /* Check if the default route is in local BGP RIB which is + * installed through redistribute or network command + */ + memset(&p, 0, sizeof(p)); + p.family = afi2family(afi); + p.prefixlen = 0; + rn = bgp_afi_node_lookup(bgp->rib[afi][safi], afi, safi, &p, NULL); + if (withdraw) { + /* Withdraw the default route advertised using default + * originate + */ if (CHECK_FLAG(subgrp->sflags, SUBGRP_STATUS_DEFAULT_ORIGINATE)) subgroup_default_withdraw_packet(subgrp); UNSET_FLAG(subgrp->sflags, SUBGRP_STATUS_DEFAULT_ORIGINATE); + + /* If default route is present in the local RIB, advertise the + * route + */ + if (rn != NULL) { + for (pi = bgp_node_get_bgp_path_info(rn); pi; + pi = pi->next) { + if (CHECK_FLAG(pi->flags, BGP_PATH_SELECTED)) + if (subgroup_announce_check( + rn, pi, subgrp, &rn->p, + &attr)) + bgp_adj_out_set_subgroup( + rn, subgrp, &attr, pi); + } + } } else { if (!CHECK_FLAG(subgrp->sflags, SUBGRP_STATUS_DEFAULT_ORIGINATE)) { - if (CHECK_FLAG(bgp->flags, BGP_FLAG_GRACEFUL_SHUTDOWN)) - bgp_attr_add_gshut_community(new_attr); - - SET_FLAG(subgrp->sflags, - SUBGRP_STATUS_DEFAULT_ORIGINATE); - subgroup_default_update_packet(subgrp, new_attr, from); - /* The 'neighbor x.x.x.x default-originate' default will * act as an * implicit withdraw for any previous UPDATEs sent for @@ -800,15 +838,37 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw) * clear adj_out for the 0.0.0.0/0 prefix in the BGP * table. */ - memset(&p, 0, sizeof(p)); - p.family = afi2family(afi); - p.prefixlen = 0; - - rn = bgp_afi_node_get(bgp->rib[afi][safi], afi, safi, - &p, NULL); - bgp_adj_out_unset_subgroup( - rn, subgrp, 0, - BGP_ADDPATH_TX_ID_FOR_DEFAULT_ORIGINATE); + if (rn != NULL) { + /* Remove the adjacency for the previously + * advertised default route + */ + adj = adj_lookup( + rn, subgrp, + BGP_ADDPATH_TX_ID_FOR_DEFAULT_ORIGINATE); + if (adj != NULL) { + /* Clean up previous advertisement. */ + if (adj->adv) + bgp_advertise_clean_subgroup( + subgrp, adj); + + /* Remove from adjacency. */ + RB_REMOVE(bgp_adj_out_rb, &rn->adj_out, + adj); + + /* Free allocated information. */ + adj_free(adj); + + bgp_unlock_node(rn); + } + } + + /* Advertise the default route */ + if (CHECK_FLAG(bgp->flags, BGP_FLAG_GRACEFUL_SHUTDOWN)) + bgp_attr_add_gshut_community(new_attr); + + SET_FLAG(subgrp->sflags, + SUBGRP_STATUS_DEFAULT_ORIGINATE); + subgroup_default_update_packet(subgrp, new_attr, from); } }