diff options
| author | Philippe Guibert <philippe.guibert@6wind.com> | 2024-03-11 11:51:55 +0100 |
|---|---|---|
| committer | Philippe Guibert <philippe.guibert@6wind.com> | 2024-11-28 09:13:53 +0100 |
| commit | 8b3b152a1a8e871002812b28d3378f76b1c5ee11 (patch) | |
| tree | 9c0bcc17479924ea14454d3859b4828fa0f504f1 /bgpd/bgp_nht.c | |
| parent | 855873aa77cf11b77b11e2696627592c370ea078 (diff) | |
bgpd: fix use real SID in BGP nexthop tracking
When receiving an SRv6 BGP update, the nexthop tracking is used
to find out the reachability of the BGP update.
> # show bgp ipv6 vpn fd00:200::/64
> Paths: (1 available, best #1)
> [..]
> 4:4::4:4 from 4:4::4:4 (4.4.4.4)
> Origin incomplete, metric 0, localpref 100, valid, internal, best (First path received)
> Extended Community: RT:52:100
> Remote label: 16
> Remote SID: 2001:db8:f4::
> Last update: Mon Mar 11 11:50:04 2024
The IPv6 address used is the "Remote SID". Actually, this value is
incomplete. Remote SID stands for the attribute value received in BGP,
while the label value determines a complement of SRv6 SID value. The
transposition technique authorises that in BGP, and in the above case,
the incoming BGP update has used the transposition length.
When there is a transposition in the SID attribute available, use the
real SID address. The nexthop tracking will use that forged address.
> # show bgp nexthop
> Current BGP nexthop cache:
> 4:4::4:4 valid [IGP metric 30], #paths 0, peer 4:4::4:4
> gate fe80::dced:1ff:fed6:878c, if ntfp3
> Last update: Mon Mar 11 11:50:02 2024
> 2001:db8:f4:1:: valid [IGP metric 0], #paths 2
> gate fe80::dced:1ff:fed6:878c, if ntfp3
Fixes: 26c747ed6c0b ("bgpd: extend make_prefix to form srv6-based prefix")
Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
Diffstat (limited to 'bgpd/bgp_nht.c')
| -rw-r--r-- | bgpd/bgp_nht.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/bgpd/bgp_nht.c b/bgpd/bgp_nht.c index 9b633b7139..ed83757ea3 100644 --- a/bgpd/bgp_nht.c +++ b/bgpd/bgp_nht.c @@ -1066,9 +1066,16 @@ static int make_prefix(int afi, struct bgp_path_info *pi, struct prefix *p) case AFI_IP6: p->family = AF_INET6; if (pi->attr->srv6_l3vpn) { - IPV6_ADDR_COPY(&(p->u.prefix6), - &(pi->attr->srv6_l3vpn->sid)); p->prefixlen = IPV6_MAX_BITLEN; + if (pi->attr->srv6_l3vpn->transposition_len != 0 && + BGP_PATH_INFO_NUM_LABELS(pi)) { + IPV6_ADDR_COPY(&p->u.prefix6, &pi->attr->srv6_l3vpn->sid); + transpose_sid(&p->u.prefix6, + decode_label(&pi->extra->labels->label[0]), + pi->attr->srv6_l3vpn->transposition_offset, + pi->attr->srv6_l3vpn->transposition_len); + } else + IPV6_ADDR_COPY(&(p->u.prefix6), &(pi->attr->srv6_l3vpn->sid)); } else if (is_bgp_static) { p->u.prefix6 = p_orig->u.prefix6; p->prefixlen = p_orig->prefixlen; |