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iof-bird / bird-2.0.1 / proto / ospf / rt.h @ 6b3f1a54

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/*
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 *      BIRD -- OSPF
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 *
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 *      (c) 2000--2004 Ondrej Filip <feela@network.cz>
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 *        (c) 2009--2014 Ondrej Zajicek <santiago@crfreenet.org>
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 *        (c) 2009--2014 CZ.NIC z.s.p.o.
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 *
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 *      Can be freely distributed and used under the terms of the GNU GPL.
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 */
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#ifndef _BIRD_OSPF_RT_H_
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#define _BIRD_OSPF_RT_H_
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#define ORT_NET 0
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#define ORT_ROUTER 1
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typedef struct orta
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{
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  u8 type;                        /* RTS_OSPF_* */
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  u8 nhs_reuse;                        /* Whether nhs nodes can be reused during merging.
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                                   See a note in rt.c:add_cand() */
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  u32 options;
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  /*
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   * For ORT_ROUTER routes, options field are router-LSA style
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   * options, with V,E,B bits. In OSPFv2, ASBRs from another areas
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   * (that we know from rt-summary-lsa) have just ORTA_ASBR in
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   * options, their real options are unknown.
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   */
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#define ORTA_ASBR OPT_RT_E
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#define ORTA_ABR  OPT_RT_B
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  /*
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   * For ORT_NET routes, there are just several flags for external routes:
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   *
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   * ORTA_PREF for external routes means that the route is preferred in AS
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   * external route selection according to 16.4.1. - it is intra-area path using
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   * non-backbone area. In other words, the forwarding address (or ASBR if
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   * forwarding address is zero) is intra-area (type == RTS_OSPF) and its area
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   * is not a backbone.
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   *
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   * ORTA_NSSA means that the entry represents an NSSA route, and ORTA_PROP
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   * means that the NSSA route has propagate-bit set. These flags are used in
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   * NSSA translation.
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   */
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#define ORTA_PREF 0x80000000
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#define ORTA_NSSA 0x40000000
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#define ORTA_PROP 0x20000000
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  u32 metric1;
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  u32 metric2;
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  u32 tag;
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  u32 rid;                        /* Router ID of real advertising router */
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  struct ospf_area *oa;
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  struct ospf_area *voa;        /* Used when route is replaced in ospf_rt_sum_tr(),
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                                   NULL otherwise */
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  struct nexthop *nhs;                /* Next hops computed during SPF */
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  struct top_hash_entry *en;        /* LSA responsible for this orta */
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}
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orta;
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typedef struct ort
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{
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  /*
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   * Most OSPF routing table entries are for computed OSPF routes, these have
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   * defined n.type. There are also few other cases: entries for configured area
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   * networks (these have area_net field set) and entries for external routes
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   * exported to OSPF (these have external_rte field set). These entries are
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   * kept even if they do not contain 'proper' rt entry. That is needed to keep
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   * allocated stable UID numbers (fn.uid), which are used as LSA IDs in OSPFv3
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   * (see fibnode_to_lsaid()) for related LSAs (network summary LSAs in the
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   * first case, external or NSSA LSAs in the second case). Entries for external
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   * routes also have a second purpose - to prevent NSSA translation of received
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   * NSSA routes if regular external routes were already originated for the same
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   * network (see check_nssa_lsa()).
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   *
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   * old_* values are here to represent the last route update. old_rta is cached
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   * (we keep reference), mainly for multipath nexthops.  old_rta == NULL means
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   * route was not in the last update, in that case other old_* values are not
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   * valid.
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   */
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  orta n;
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  u32 old_metric1, old_metric2, old_tag, old_rid;
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  rta *old_rta;
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  u32 lsa_id;
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  u8 external_rte;
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  u8 area_net;
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  u8 keep;
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  struct fib_node fn;
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}
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ort;
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static inline int rt_is_nssa(ort *nf)
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{ return nf->n.options & ORTA_NSSA; }
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/*
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 * Invariants for structs top_hash_entry (nodes of LSA db)
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 * enforced by SPF calculation for final nodes (color == INSPF):
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 * - only router, network and AS-external LSAs
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 * - lsa.age < LSA_MAXAGE
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 * - dist < LSINFINITY (or 2*LSINFINITY for ext-LSAs)
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 * - nhs is non-NULL unless the node is oa->rt (calculating router itself)
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 * - beware, nhs is not valid after SPF calculation
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 *
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 * Invariants for structs orta nodes of fib tables po->rtf, oa->rtr:
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 * - nodes may be invalid (n.type == 0), in that case other invariants don't hold
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 * - n.metric1 may be at most a small multiple of LSINFINITY,
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 *   therefore sums do not overflow
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 * - n.oa is always non-NULL
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 * - n.nhs is always non-NULL unless it is configured stubnet
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 * - n.en is non-NULL for external routes, NULL for intra/inter area routes.
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 * - oa->rtr does not contain calculating router itself
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 *
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 * There are four types of nexthops in nhs fields:
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 * - gateway nexthops (non-NULL iface, gw != IPA_NONE)
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 * - device nexthops (non-NULL iface, gw == IPA_NONE)
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 * - dummy vlink nexthops (NULL iface, gw == IPA_NONE)
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 * - configured stubnets (nhs is NULL, only RTS_OSPF orta nodes in po->rtf)
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 *
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 * Dummy vlink nexthops and configured stubnets cannot be mixed with
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 * regular ones, nhs field contains either list of gateway+device nodes,
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 * one vlink node, or NULL for configured stubnet.
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 *
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 * Dummy vlink nexthops can appear in both network (rtf) and backbone area router
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 * (rtr) tables for regular and inter-area routes, but only if areano > 1. They are
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 * replaced in ospf_rt_sum_tr() and removed in ospf_rt_abr1(), therefore cannot
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 * appear in ASBR pre-selection and external routes processing.
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 */
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void ospf_rt_spf(struct ospf_proto *p);
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void ospf_rt_initort(struct fib_node *fn);
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#endif /* _BIRD_OSPF_RT_H_ */