OSPF: Fix next hop calculation for PtP links in IPv4 OSPFv3-AF
In such case, next hop has to be taken from Link-LSA like in broadcast case, not from neighbor source address like in other PtP cases. Also add some checks, comments and code cleanup.
This commit is contained in:
Ondrej Zajicek (work)
parent
d3f4f92b0e
commit
f097f7659c
1 changed files with 82 additions and 33 deletions
109
proto/ospf/rt.c
109
proto/ospf/rt.c
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@ -10,9 +10,7 @@
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#include "ospf.h"
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static void add_cand(list * l, struct top_hash_entry *en,
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struct top_hash_entry *par, u32 dist,
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struct ospf_area *oa, int i);
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static void add_cand(struct ospf_area *oa, struct top_hash_entry *en, struct top_hash_entry *par, u32 dist, int i, uint lif, uint nif);
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static void rt_sync(struct ospf_proto *p);
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@ -509,7 +507,7 @@ spfa_process_rt(struct ospf_proto *p, struct ospf_area *oa, struct top_hash_entr
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break;
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}
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add_cand(&oa->cand, tmp, act, act->dist + rtl.metric, oa, i);
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add_cand(oa, tmp, act, act->dist + rtl.metric, i, rtl.lif, rtl.nif);
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}
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}
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@ -532,7 +530,7 @@ spfa_process_net(struct ospf_proto *p, struct ospf_area *oa, struct top_hash_ent
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for (i = 0; i < cnt; i++)
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{
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tmp = ospf_hash_find_rt(p->gr, oa->areaid, ln->routers[i]);
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add_cand(&oa->cand, tmp, act, act->dist, oa, -1);
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add_cand(oa, tmp, act, act->dist, -1, 0, 0);
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}
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}
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@ -651,7 +649,8 @@ ospf_rt_spfa(struct ospf_area *oa)
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}
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static int
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link_back(struct ospf_area *oa, struct top_hash_entry *en, struct top_hash_entry *par)
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link_back(struct ospf_area *oa, struct top_hash_entry *en,
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struct top_hash_entry *par, uint lif, uint nif)
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{
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struct ospf_proto *p = oa->po;
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struct ospf_lsa_rt_walk rtl;
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@ -689,6 +688,10 @@ link_back(struct ospf_area *oa, struct top_hash_entry *en, struct top_hash_entry
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tmp = ospf_hash_find_net(p->gr, oa->areaid, rtl.id, rtl.nif);
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if (tmp == par)
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{
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/*
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* Note that there may be multiple matching Rt-fields if router 'en'
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* have multiple interfaces to net 'par'. Perhaps we should do ECMP.
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*/
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if (ospf_is_v2(p))
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en->lb = ipa_from_u32(rtl.data);
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else
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@ -700,7 +703,13 @@ link_back(struct ospf_area *oa, struct top_hash_entry *en, struct top_hash_entry
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case LSART_VLNK:
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case LSART_PTP:
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/* Not necessary the same link, see RFC 2328 [23] */
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/*
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* For OSPFv2, not necessary the same link, see RFC 2328 [23].
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* For OSPFv3, we verify that by comparing nif and lif fields.
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*/
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if (ospf_is_v3(p) && ((rtl.lif != nif) || (rtl.nif != lif)))
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break;
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tmp = ospf_hash_find_rt(p->gr, oa->areaid, rtl.id);
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if (tmp == par)
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return 1;
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@ -1679,13 +1688,27 @@ inherit_nexthops(struct nexthop *pn)
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return pn && (ipa_nonzero(pn->gw) || !pn->iface);
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}
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static inline ip_addr
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link_lsa_lladdr(struct ospf_proto *p, struct top_hash_entry *en)
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{
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struct ospf_lsa_link *link_lsa = en->lsa_body;
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ip6_addr ll = link_lsa->lladdr;
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if (ip6_zero(ll))
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return IPA_NONE;
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return ospf_is_ip4(p) ? ipa_from_ip4(ospf3_6to4(ll)) : ipa_from_ip6(ll);
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}
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static struct nexthop *
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calc_next_hop(struct ospf_area *oa, struct top_hash_entry *en,
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struct top_hash_entry *par, int pos)
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struct top_hash_entry *par, int pos, uint lif, uint nif)
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{
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struct ospf_proto *p = oa->po;
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struct nexthop *pn = par->nhs;
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struct ospf_iface *ifa;
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struct top_hash_entry *link = NULL;
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struct ospf_iface *ifa = NULL;
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ip_addr nh = IPA_NONE;
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u32 rid = en->lsa.rt;
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/* 16.1.1. The next hop calculation */
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@ -1710,6 +1733,9 @@ calc_next_hop(struct ospf_area *oa, struct top_hash_entry *en,
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if (!ifa)
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return NULL;
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if (ospf_is_v3(p) && (ifa->iface_id != lif))
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log(L_WARN "%s: Inconsistent interface ID %u/%u", p->p.name, ifa->iface_id, lif);
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return new_nexthop(p, IPA_NONE, ifa->iface, ifa->ecmp_weight);
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}
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@ -1720,14 +1746,44 @@ calc_next_hop(struct ospf_area *oa, struct top_hash_entry *en,
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if (!ifa)
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return NULL;
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if (ospf_is_v3(p) && (ifa->iface_id != lif))
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log(L_WARN "%s: Inconsistent interface ID %u/%u", p->p.name, ifa->iface_id, lif);
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if (ifa->type == OSPF_IT_VLINK)
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return new_nexthop(p, IPA_NONE, NULL, 0);
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/* FIXME: On physical PtP links we may skip next-hop altogether */
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if (ospf_is_v2(p) || ospf_is_ip6(p))
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{
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/*
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* In this case, next-hop is a source address from neighbor's packets.
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* That is necessary for OSPFv2 and practical for OSPFv3 (as it works even
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* if neighbor uses LinkLSASuppression), but does not work with OSPFv3-AF
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* on IPv4 topology, where src is IPv6 but next-hop should be IPv4.
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*/
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struct ospf_neighbor *m = find_neigh(ifa, rid);
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if (!m || (m->state != NEIGHBOR_FULL))
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return NULL;
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return new_nexthop(p, m->ip, ifa->iface, ifa->ecmp_weight);
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nh = m->ip;
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}
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else
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{
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/*
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* Next-hop is taken from lladdr field of Link-LSA, based on Neighbor
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* Iface ID (nif) field in our Router-LSA, which is just nbr->iface_id.
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*/
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link = ospf_hash_find(p->gr, ifa->iface_id, nif, rid, LSA_T_LINK);
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if (!link)
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return NULL;
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nh = link_lsa_lladdr(p, link);
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if (ipa_zero(nh))
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return NULL;
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}
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return new_nexthop(p, nh, ifa->iface, ifa->ecmp_weight);
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}
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/* The third case - bcast or nbma neighbor */
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@ -1754,21 +1810,14 @@ calc_next_hop(struct ospf_area *oa, struct top_hash_entry *en,
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* Next-hop is taken from lladdr field of Link-LSA, en->lb_id
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* is computed in link_back().
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*/
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struct top_hash_entry *lhe;
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lhe = ospf_hash_find(p->gr, pn->iface->index, en->lb_id, rid, LSA_T_LINK);
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if (!lhe)
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link = ospf_hash_find(p->gr, pn->iface->index, en->lb_id, rid, LSA_T_LINK);
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if (!link)
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return NULL;
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struct ospf_lsa_link *llsa = lhe->lsa_body;
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if (ip6_zero(llsa->lladdr))
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nh = link_lsa_lladdr(p, link);
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if (ipa_zero(nh))
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return NULL;
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ip_addr nh = ospf_is_ip4(p) ?
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ipa_from_ip4(ospf3_6to4(llsa->lladdr)) :
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ipa_from_ip6(llsa->lladdr);
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return new_nexthop(p, nh, pn->iface, pn->weight);
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}
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}
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@ -1782,8 +1831,8 @@ calc_next_hop(struct ospf_area *oa, struct top_hash_entry *en,
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/* Add LSA into list of candidates in Dijkstra's algorithm */
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static void
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add_cand(list * l, struct top_hash_entry *en, struct top_hash_entry *par,
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u32 dist, struct ospf_area *oa, int pos)
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add_cand(struct ospf_area *oa, struct top_hash_entry *en, struct top_hash_entry *par,
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u32 dist, int pos, uint lif, uint nif)
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{
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struct ospf_proto *p = oa->po;
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node *prev, *n;
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@ -1813,10 +1862,10 @@ add_cand(list * l, struct top_hash_entry *en, struct top_hash_entry *par,
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return;
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/* We should check whether there is a reverse link from en to par, */
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if (!link_back(oa, en, par))
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if (!link_back(oa, en, par, lif, nif))
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return;
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struct nexthop *nhs = calc_next_hop(oa, en, par, pos);
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struct nexthop *nhs = calc_next_hop(oa, en, par, pos, lif, nif);
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if (!nhs)
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{
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log(L_WARN "%s: Cannot find next hop for LSA (Type: %04x, Id: %R, Rt: %R)",
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@ -1873,20 +1922,20 @@ add_cand(list * l, struct top_hash_entry *en, struct top_hash_entry *par,
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prev = NULL;
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if (EMPTY_LIST(*l))
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if (EMPTY_LIST(oa->cand))
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{
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add_head(l, &en->cn);
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add_head(&oa->cand, &en->cn);
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}
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else
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{
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WALK_LIST(n, *l)
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WALK_LIST(n, oa->cand)
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{
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act = SKIP_BACK(struct top_hash_entry, cn, n);
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if ((act->dist > dist) ||
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((act->dist == dist) && (act->lsa_type == LSA_T_RT)))
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{
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if (prev == NULL)
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add_head(l, &en->cn);
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add_head(&oa->cand, &en->cn);
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else
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insert_node(&en->cn, prev);
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added = 1;
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@ -1897,7 +1946,7 @@ add_cand(list * l, struct top_hash_entry *en, struct top_hash_entry *par,
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if (!added)
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{
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add_tail(l, &en->cn);
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add_tail(&oa->cand, &en->cn);
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}
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}
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}
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