diff options
Diffstat (limited to 'proto/ospf/topology.c')
| -rw-r--r-- | proto/ospf/topology.c | 71 |
1 files changed, 62 insertions, 9 deletions
diff --git a/proto/ospf/topology.c b/proto/ospf/topology.c index 182f644a..6f7905bc 100644 --- a/proto/ospf/topology.c +++ b/proto/ospf/topology.c @@ -30,11 +30,64 @@ void flush_prefix_net_lsa(struct ospf_iface *ifa); #define ipa_to_rid(x) _I3(x) #endif -/* FIXME very ugly hack */ + #ifdef OSPFv2 -#define ipa_to_lsaid(x) _I(x) +static inline u32 +fibnode_to_lsaid(struct proto_ospf *po, struct fib_node *fn) +{ + /* We have to map IP prefixes to u32 in such manner that resulting + u32 interpreted as IP address is a member of given + prefix. Therefore, /32 prefix have to be mapped on itself. + All received prefixes have to be mapped on different u32s. + + We have an assumption that if there is nontrivial (non-/32) + network prefix, then there is not /32 prefix for the first + and the last IP address of the network (these are usually + reserved, therefore it is not an important restriction). + The network prefix is mapped to the first or the last + IP address in the manner that disallow collisions - we + use IP address that cannot be used by parent prefix. + + For example: + 192.168.0.0/24 maps to 192.168.0.255 + 192.168.1.0/24 maps to 192.168.1.0 + because 192.168.0.0 and 192.168.1.255 might be used by + 192.168.0.0/23 . + + This is not compatible with older RFC 1583, so we have an option + to the RFC 1583 compatible assignment (that always uses the first + address) which disallows subnetting. + + Appendig E of RFC 2328 suggests different algorithm, that tries + to maximize both compatibility and subnetting. But as it is not + possible to have both reliably and the suggested algorithm was + unnecessary complicated and it does crazy things like changing + LSA ID for a network because different network appeared, we + choose a different way. */ + + u32 id = _I(fn->prefix); + + if ((po->rfc1583) || (fn->pxlen == 0) || (fn->pxlen == 32)) + return id; + + if (id & (1 << (32 - fn->pxlen))) + return id; + else + return id | ~u32_mkmask(fn->pxlen); +} + #else /* OSPFv3 */ -#define ipa_to_lsaid(x) _I0(x) ^ _I1(x) ^ _I2(x) ^ _I3(x) + +static inline u32 +fibnode_to_lsaid(struct proto_ospf *po, struct fib_node *fn) +{ + /* In OSPFv3, it is simpler. There is not a requirement + for membership of the result in input network, so we + just use hash-based unique ID. */ + + return fn->uid; +} + #endif @@ -660,8 +713,7 @@ originate_sum_lsa(struct ospf_area *oa, struct fib_node *fn, int type, int metri if (type == ORT_NET) { - /* FIXME proper handling of LSA IDs and check for the same network */ - lsa.id = ipa_to_lsaid(fn->prefix); + lsa.id = fibnode_to_lsaid(po, fn); lsa.type = LSA_T_SUM_NET; } else @@ -710,8 +762,7 @@ flush_sum_lsa(struct ospf_area *oa, struct fib_node *fn, int type) lsa.rt = rid; if (type == ORT_NET) { - /* FIXME proper handling of LSA IDs and check for the same network */ - lsa.id = ipa_to_lsaid(fn->prefix); + lsa.id = fibnode_to_lsaid(po, fn); lsa.type = LSA_T_SUM_NET; } else @@ -721,6 +772,8 @@ flush_sum_lsa(struct ospf_area *oa, struct fib_node *fn, int type) lsa.type = LSA_T_SUM_RT; } + /* FIXME check for the same network */ + if ((en = ospf_hash_find_header(po->gr, oa->areaid, &lsa)) != NULL) { struct ospf_lsa_sum *sum = en->lsa_body; @@ -892,7 +945,7 @@ originate_ext_lsa(net * n, rte * e, struct proto_ospf *po, #endif /* FIXME proper handling of LSA IDs and check for the same network */ - lsa.id = ipa_to_lsaid(n->n.prefix); + lsa.id = fibnode_to_lsaid(po, &n->n); if ((en = ospf_hash_find_header(po->gr, 0, &lsa)) != NULL) { @@ -927,7 +980,7 @@ flush_ext_lsa(net *n, struct proto_ospf *po) n->n.prefix, n->n.pxlen); /* FIXME proper handling of LSA IDs and check for the same network */ - u32 lsaid = ipa_to_lsaid(n->n.prefix); + u32 lsaid = fibnode_to_lsaid(po, &n->n); if (en = ospf_hash_find(po->gr, 0, lsaid, rid, LSA_T_EXT)) { |