diff options
| author | Ondrej Zajicek <santiago@crfreenet.org> | 2009-12-07 12:33:20 +0300 |
|---|---|---|
| committer | Denis Ovsienko <infrastation@yandex.ru> | 2009-12-07 12:33:20 +0300 |
| commit | 64bf3ab7291cc5c39c5add0dc1a7de447914248b (patch) | |
| tree | d5ae874814083d89815e6c521b42d0f3eaaec69c | |
| parent | 2eb445e1c22e36d07e2dbfd302ff438c4190b9fe (diff) | |
ospf6d: review LSA sequence number comparison
It seems that there is a bug in ospf6d in ospf6_lsa_compare(): If LSA A
has sequence number smaller than 0x80000000 and LSA B has sequence
number larger than 0x80000000, ospf6_lsa_compare() returns that B is
more recent than A, although RFC says that sequence numbers should be
compared as signed numbers (0x8000001 smallest and 0x7FFFFFFF largest).
In ospfd, the function ospf_lsa_more_recent() has it right.
The problem appears when Quagga is used together with OSPFv3 in
development version of BIRD daemon ( http://bird.network.cz/ ),
which creates LSAs with maximum sequence number (0x7FFFFFFF)
as a part of flushing/premature aging LSA from OSPF area.
Because both daemons has different idea of which LSA instance
is more recent, it would lead to LSA storm.
| -rw-r--r-- | ospf6d/ospf6_lsa.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/ospf6d/ospf6_lsa.c b/ospf6d/ospf6_lsa.c index 07d9f91e..c1db3741 100644 --- a/ospf6d/ospf6_lsa.c +++ b/ospf6d/ospf6_lsa.c @@ -256,7 +256,7 @@ ospf6_lsa_premature_aging (struct ospf6_lsa *lsa) int ospf6_lsa_compare (struct ospf6_lsa *a, struct ospf6_lsa *b) { - signed long seqnuma, seqnumb; + int seqnuma, seqnumb; u_int16_t cksuma, cksumb; u_int16_t agea, ageb; @@ -264,16 +264,13 @@ ospf6_lsa_compare (struct ospf6_lsa *a, struct ospf6_lsa *b) assert (b && b->header); assert (OSPF6_LSA_IS_SAME (a, b)); - seqnuma = ((signed long) ntohl (a->header->seqnum)) - - (signed long) INITIAL_SEQUENCE_NUMBER; - seqnumb = ((signed long) ntohl (b->header->seqnum)) - - (signed long) INITIAL_SEQUENCE_NUMBER; + seqnuma = (int) ntohl (a->header->seqnum); + seqnumb = (int) ntohl (b->header->seqnum); /* compare by sequence number */ - /* XXX, LS sequence number wrapping */ if (seqnuma > seqnumb) return -1; - else if (seqnuma < seqnumb) + if (seqnuma < seqnumb) return 1; /* Checksum */ |