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OSPF: Allow loopback nexthop in OSPFv3-IPv4
In OSPFv3-IPv4 there is no requirement that link-local next hop announced in Link-LSA must be in interface address range. Therefore, for interfaces that do not have IPv4 address we can use some loopback IP address and announce it as a next hop. Also we should accept such address.
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@ -217,7 +217,8 @@ neigh_find(struct proto *p, ip_addr a, struct iface *iface, uint flags)
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struct ifa *addr = NULL;
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WALK_LIST(n, neigh_hash_table[h]) /* Search the cache */
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if ((n->proto == p) && ipa_equal(n->addr, a) && (n->ifreq == iface))
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if ((n->proto == p) && ipa_equal(n->addr, a) && (n->ifreq == iface) &&
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((n->flags & NEF_ONLINK) == (flags & NEF_ONLINK)))
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return n;
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if (flags & NEF_IFACE)
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@ -252,6 +252,7 @@ struct ospf_proto
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u32 last_vlink_id; /* Interface IDs for vlinks (starts at 0x80000000) */
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struct tbf log_pkt_tbf; /* TBF for packet messages */
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struct tbf log_lsa_tbf; /* TBF for LSA messages */
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ip_addr loopback_addr; /* IP address used as common next hop (in OSPFv3-IPv4) */
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};
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struct ospf_area
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@ -331,6 +332,7 @@ struct ospf_iface
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struct top_hash_entry **flood_queue; /* LSAs queued for LSUPD */
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u8 update_link_lsa;
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u8 update_net_lsa;
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u8 loopback_addr_used; /* The Link-LSA depends on p->loopback_addr */
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u16 flood_queue_used; /* The current number of LSAs in flood_queue */
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u16 flood_queue_size; /* The maximum number of LSAs in flood_queue */
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int fadj; /* Number of fully adjacent neighbors */
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@ -2038,6 +2038,14 @@ again1:
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{
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neighbor *nbr = neigh_find(&p->p, nh->gw, nh->iface,
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(nh->flags & RNF_ONLINK) ? NEF_ONLINK : 0);
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/* According to RFC 5838 2.5 Direct Interface Address */
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if (ospf_is_v3(p) && !nbr && ipa_is_ip4(nh->gw))
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{
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nh->flags |= RNF_ONLINK;
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nbr = neigh_find(&p->p, nh->gw, nh->iface, NEF_ONLINK);
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}
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if (!nbr || (nbr->scope == SCOPE_HOST))
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{ reset_ri(nf); break; }
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}
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@ -1402,6 +1402,46 @@ lsab_put_prefix(struct ospf_proto *p, net_addr *n, u32 cost)
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ospf3_put_prefix(buf, n, flags, cost);
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}
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static inline void
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update_loopback_addr(struct ospf_proto *p)
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{
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ip_addr old_addr = p->loopback_addr;
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ip_addr best_addr = IPA_NONE;
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int best_pref = 0;
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struct ospf_iface *ifa;
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WALK_LIST(ifa, p->iface_list)
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{
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if (ifa->type == OSPF_IT_VLINK)
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continue;
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struct ifa *a;
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WALK_LIST(a, ifa->iface->addrs)
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{
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if ((a->prefix.type != ospf_get_af(p)) ||
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(a->flags & IA_SECONDARY) ||
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(a->scope <= SCOPE_LINK))
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continue;
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int pref = (a->flags & IA_HOST) ? 3 : (ifa->stub ? 2 : 1);
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if ((pref > best_pref) || ((pref == best_pref) && ipa_equal(a->ip, old_addr)))
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{
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best_addr = a->ip;
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best_pref = pref;
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}
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}
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}
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if (ipa_equal(best_addr, old_addr))
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return;
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p->loopback_addr = best_addr;
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WALK_LIST(ifa, p->iface_list)
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if (ifa->loopback_addr_used)
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ospf_notify_link_lsa(ifa);
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}
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static void
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prepare_link_lsa_body(struct ospf_proto *p, struct ospf_iface *ifa)
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{
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@ -1427,6 +1467,12 @@ prepare_link_lsa_body(struct ospf_proto *p, struct ospf_iface *ifa)
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i++;
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}
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if (ospf_is_ip4(p) && ipa_zero(nh))
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{
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nh = p->loopback_addr;
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ifa->loopback_addr_used = 1;
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}
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/* Filling the preallocated header */
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struct ospf_lsa_link *ll = p->lsab;
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ll->options = ifa->oa->options | (ifa->priority << 24);
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@ -1853,6 +1899,9 @@ ospf_update_topology(struct ospf_proto *p)
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}
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}
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if (ospf_is_v3(p) && ospf_is_ip4(p))
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update_loopback_addr(p);
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WALK_LIST(ifa, p->iface_list)
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{
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if (ifa->type == OSPF_IT_VLINK)
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@ -1860,6 +1909,8 @@ ospf_update_topology(struct ospf_proto *p)
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if (ifa->update_link_lsa)
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{
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ifa->loopback_addr_used = 0;
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if ((ifa->state > OSPF_IS_LOOP) && !ifa->link_lsa_suppression)
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ospf_originate_link_lsa(p, ifa);
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else
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