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Implement proper LSA ID generation.

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This commit is contained in:
Ondrej Zajicek
2009-10-07 21:10:29 +01:00
parent 9f0ba7b1c7
commit d82fc18d75
5 changed files with 106 additions and 13 deletions
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71
proto/ospf/topology.c
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@@ -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))
{