1 /*
2 * BIRD -- OSPF
3 *
4 * (c) 2000--2004 Ondrej Filip <feela@network.cz>
5 * (c) 2009--2014 Ondrej Zajicek <santiago@crfreenet.org>
6 * (c) 2009--2014 CZ.NIC z.s.p.o.
7 *
8 * Can be freely distributed and used under the terms of the GNU GPL.
9 */
10
11 #ifndef _BIRD_OSPF_RT_H_
12 #define _BIRD_OSPF_RT_H_
13
14
15 #define ORT_NET 0
16 #define ORT_ROUTER 1
17
18 typedef struct orta
19 {
20 u8 type; /* RTS_OSPF_* */
21 u8 nhs_reuse; /* Whether nhs nodes can be reused during merging.
22 See a note in rt.c:add_cand() */
23 u32 options;
24 /*
25 * For ORT_ROUTER routes, options field are router-LSA style
26 * options, with V,E,B bits. In OSPFv2, ASBRs from another areas
27 * (that we know from rt-summary-lsa) have just ORTA_ASBR in
28 * options, their real options are unknown.
29 */
30 #define ORTA_ASBR OPT_RT_E
31 #define ORTA_ABR OPT_RT_B
32 /*
33 * For ORT_NET routes, there are just several flags for external routes:
34 *
35 * ORTA_PREF for external routes means that the route is preferred in AS
36 * external route selection according to 16.4.1. - it is intra-area path using
37 * non-backbone area. In other words, the forwarding address (or ASBR if
38 * forwarding address is zero) is intra-area (type == RTS_OSPF) and its area
39 * is not a backbone.
40 *
41 * ORTA_NSSA means that the entry represents an NSSA route, and ORTA_PROP
42 * means that the NSSA route has propagate-bit set. These flags are used in
43 * NSSA translation.
44 */
45 #define ORTA_PREF 0x80000000
46 #define ORTA_NSSA 0x40000000
47 #define ORTA_PROP 0x20000000
48
49 u32 metric1;
50 u32 metric2;
51 u32 tag;
52 u32 rid; /* Router ID of real advertising router */
53 struct ospf_area *oa;
54 struct ospf_area *voa; /* Used when route is replaced in ospf_rt_sum_tr(),
55 NULL otherwise */
56 struct nexthop *nhs; /* Next hops computed during SPF */
57 struct top_hash_entry *en; /* LSA responsible for this orta */
58 }
59 orta;
60
61 typedef struct ort
62 {
63 /*
64 * Most OSPF routing table entries are for computed OSPF routes, these have
65 * defined n.type. There are also few other cases: entries for configured area
66 * networks (these have area_net field set) and entries for external routes
67 * exported to OSPF (these have external_rte field set). These entries are
68 * kept even if they do not contain 'proper' rt entry. That is needed to keep
69 * allocated stable UID numbers (fn.uid), which are used as LSA IDs in OSPFv3
70 * (see fibnode_to_lsaid()) for related LSAs (network summary LSAs in the
71 * first case, external or NSSA LSAs in the second case). Entries for external
72 * routes also have a second purpose - to prevent NSSA translation of received
73 * NSSA routes if regular external routes were already originated for the same
74 * network (see check_nssa_lsa()).
75 *
76 * old_* values are here to represent the last route update. old_rta is cached
77 * (we keep reference), mainly for multipath nexthops. old_rta == NULL means
78 * route was not in the last update, in that case other old_* values are not
79 * valid.
80 */
81 orta n;
82 u32 old_metric1, old_metric2, old_tag, old_rid;
83 rta *old_rta;
84 u32 lsa_id;
85 u8 external_rte;
86 u8 area_net;
87 u8 keep;
88
89 struct fib_node fn;
90 }
91 ort;
92
rt_is_nssa(ort * nf)93 static inline int rt_is_nssa(ort *nf)
94 { return nf->n.options & ORTA_NSSA; }
95
96
97 /*
98 * Invariants for structs top_hash_entry (nodes of LSA db)
99 * enforced by SPF calculation for final nodes (color == INSPF):
100 * - only router, network and AS-external LSAs
101 * - lsa.age < LSA_MAXAGE
102 * - dist < LSINFINITY (or 2*LSINFINITY for ext-LSAs)
103 * - nhs is non-NULL unless the node is oa->rt (calculating router itself)
104 * - beware, nhs is not valid after SPF calculation
105 *
106 * Invariants for structs orta nodes of fib tables po->rtf, oa->rtr:
107 * - nodes may be invalid (n.type == 0), in that case other invariants don't hold
108 * - n.metric1 may be at most a small multiple of LSINFINITY,
109 * therefore sums do not overflow
110 * - n.oa is always non-NULL
111 * - n.nhs is always non-NULL unless it is configured stubnet
112 * - n.en is non-NULL for external routes, NULL for intra/inter area routes.
113 * - oa->rtr does not contain calculating router itself
114 *
115 * There are four types of nexthops in nhs fields:
116 * - gateway nexthops (non-NULL iface, gw != IPA_NONE)
117 * - device nexthops (non-NULL iface, gw == IPA_NONE)
118 * - dummy vlink nexthops (NULL iface, gw == IPA_NONE)
119 * - configured stubnets (nhs is NULL, only RTS_OSPF orta nodes in po->rtf)
120 *
121 * Dummy vlink nexthops and configured stubnets cannot be mixed with
122 * regular ones, nhs field contains either list of gateway+device nodes,
123 * one vlink node, or NULL for configured stubnet.
124 *
125 * Dummy vlink nexthops can appear in both network (rtf) and backbone area router
126 * (rtr) tables for regular and inter-area routes, but only if areano > 1. They are
127 * replaced in ospf_rt_sum_tr() and removed in ospf_rt_abr1(), therefore cannot
128 * appear in ASBR pre-selection and external routes processing.
129 */
130
131 void ospf_rt_spf(struct ospf_proto *p);
132 void ospf_rt_initort(struct fib_node *fn);
133 void ospf_update_gr_recovery(struct ospf_proto *p);
134
135
136 #endif /* _BIRD_OSPF_RT_H_ */
137