Internet on FIRE

/*

 *      BIRD -- OSPF

 *

 *      (c) 2000--2004 Ondrej Filip <feela@network.cz>

 *        (c) 2009--2014 Ondrej Zajicek <santiago@crfreenet.org>

 *        (c) 2009--2014 CZ.NIC z.s.p.o.

 *

 *      Can be freely distributed and used under the terms of the GNU GPL.

 */

#ifndef _BIRD_OSPF_RT_H_

#define _BIRD_OSPF_RT_H_

#define ORT_NET 0

#define ORT_ROUTER 1

typedef struct orta

{

  u8 type;                        /* RTS_OSPF_* */

  u8 nhs_reuse;                        /* Whether nhs nodes can be reused during merging */

  u32 options;

  /*

   * For ORT_ROUTER routes, options field are router-LSA style

   * options, with V,E,B bits. In OSPFv2, ASBRs from another areas

   * (that we know from rt-summary-lsa) have just ORTA_ASBR in

   * options, their real options are unknown.

   */

#define ORTA_ASBR OPT_RT_E

#define ORTA_ABR  OPT_RT_B

  /*

   * For ORT_NET routes, there are just several flags for external routes:

   *

   * ORTA_PREF for external routes means that the route is preferred in AS

   * external route selection according to 16.4.1. - it is intra-area path using

   * non-backbone area. In other words, the forwarding address (or ASBR if

   * forwarding address is zero) is intra-area (type == RTS_OSPF) and its area

   * is not a backbone.

   *

   * ORTA_NSSA means that the entry represents an NSSA route, and ORTA_PROP

   * means that the NSSA route has propagate-bit set. These flags are used in

   * NSSA translation.

   */

#define ORTA_PREF 0x80000000

#define ORTA_NSSA 0x40000000

#define ORTA_PROP 0x20000000

  u32 metric1;

  u32 metric2;

  u32 tag;

  u32 rid;                        /* Router ID of real advertising router */

  struct ospf_area *oa;

  struct ospf_area *voa;        /* Used when route is replaced in ospf_rt_sum_tr(),

                                   NULL otherwise */

  struct mpnh *nhs;                /* Next hops computed during SPF */

  struct top_hash_entry *en;        /* LSA responsible for this orta */

}

orta;

typedef struct ort

{

  /*

   * Most OSPF routing table entries are for computed OSPF routes, these have

   * defined n.type. There are also few other cases: entries for configured area

   * networks (these have area_net field set) and entries for external routes

   * exported to OSPF (these have external_rte field set). These entries are

   * kept even if they do not contain 'proper' rt entry. That is needed to keep

   * allocated stable UID numbers (fn.uid), which are used as LSA IDs in OSPFv3

   * (see fibnode_to_lsaid()) for related LSAs (network summary LSAs in the

   * first case, external or NSSA LSAs in the second case). Entries for external

   * routes also have a second purpose - to prevent NSSA translation of received

   * NSSA routes if regular external routes were already originated for the same

   * network (see check_nssa_lsa()).

   *

   * old_* values are here to represent the last route update. old_rta is cached

   * (we keep reference), mainly for multipath nexthops.  old_rta == NULL means

   * route was not in the last update, in that case other old_* values are not

   * valid.

   */

  struct fib_node fn;

  orta n;

  u32 old_metric1, old_metric2, old_tag, old_rid;

  rta *old_rta;

  u8 external_rte;

  u8 area_net;

}

ort;

static inline int rt_is_nssa(ort *nf)

{ return nf->n.options & ORTA_NSSA; }

/*

 * Invariants for structs top_hash_entry (nodes of LSA db)

 * enforced by SPF calculation for final nodes (color == INSPF):

 * - only router, network and AS-external LSAs

 * - lsa.age < LSA_MAXAGE

 * - dist < LSINFINITY (or 2*LSINFINITY for ext-LSAs)

 * - nhs is non-NULL unless the node is oa->rt (calculating router itself)

 * - beware, nhs is not valid after SPF calculation

 *

 * Invariants for structs orta nodes of fib tables po->rtf, oa->rtr:

 * - nodes may be invalid (n.type == 0), in that case other invariants don't hold

 * - n.metric1 may be at most a small multiple of LSINFINITY,

 *   therefore sums do not overflow

 * - n.oa is always non-NULL

 * - n.nhs is always non-NULL unless it is configured stubnet

 * - n.en is non-NULL for external routes, NULL for intra/inter area routes.

 * - oa->rtr does not contain calculating router itself

 *

 * There are four types of nexthops in nhs fields:

 * - gateway nexthops (non-NULL iface, gw != IPA_NONE)

 * - device nexthops (non-NULL iface, gw == IPA_NONE)

 * - dummy vlink nexthops (NULL iface, gw == IPA_NONE)

 * - configured stubnets (nhs is NULL, only RTS_OSPF orta nodes in po->rtf)

 *

 * Dummy vlink nexthops and configured stubnets cannot be mixed with

 * regular ones, nhs field contains either list of gateway+device nodes,

 * one vlink node, or NULL for configured stubnet.

 *

 * Dummy vlink nexthops can appear in both network (rtf) and backbone area router

 * (rtr) tables for regular and inter-area routes, but only if areano > 1. They are

 * replaced in ospf_rt_sum_tr() and removed in ospf_rt_abr1(), therefore cannot

 * appear in ASBR pre-selection and external routes processing.

 */

void ospf_rt_spf(struct ospf_proto *p);

void ospf_rt_initort(struct fib_node *fn);

#endif /* _BIRD_OSPF_RT_H_ */