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bgpd: fix invalid ipv4-vpn nexthop for IPv6 peer

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Given that two routers are connected each other and they have IPv6
addresses and they establish BGP peer with extended-nexthop capability
and one router tries to advertise locally-generated IPv4-VPN routes to
other router.

In this situation, bgpd on the router that tries to advertise IPv4-VPN
routes will be crashed with "invalid MP nexthop length (AFI IP6)".

This issue is happened because MP_REACH_NLRI path attribute is not
generated correctly when ipv4-vpn routes are advertised to IPv6 peer.
When IPv4 routes are leaked from VRF RIB, the nexthop of these routes
are also IPv4 address (0.0.0.0/0 or specific addresses). However,
bgp_packet_mpattr_start only covers the case of IPv6 nexthop (for IPv6
peer).

ipv4-unicast routes were not affected by this issue because the case of
IPv4 nexthop is covered in `else` block.

Signed-off-by: Ryoga Saito <ryoga.saito@linecorp.com>
This commit is contained in:
Ryoga Saito 2022-11-12 17:45:19 +09:00
parent 3db8aa8750
commit 63e7ddb509
1 changed files with 6 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
bgpd/bgp_attr.c
View File

@ -3887,13 +3887,6 @@ size_t bgp_packet_mpattr_start(struct stream *s, struct peer *peer, afi_t afi,
} break;
case SAFI_MPLS_VPN: {
if (attr->mp_nexthop_len
== BGP_ATTR_NHLEN_IPV6_GLOBAL) {
stream_putc(s, 24);
stream_putl(s, 0); /* RD = 0, per RFC */
stream_putl(s, 0);
stream_put(s, &attr->mp_nexthop_global,
IPV6_MAX_BYTELEN);
} else if (attr->mp_nexthop_len
== BGP_ATTR_NHLEN_IPV6_GLOBAL_AND_LL) {
stream_putc(s, 48);
stream_putl(s, 0); /* RD = 0, per RFC */
@ -3904,6 +3897,12 @@ size_t bgp_packet_mpattr_start(struct stream *s, struct peer *peer, afi_t afi,
stream_putl(s, 0);
stream_put(s, &attr->mp_nexthop_local,
IPV6_MAX_BYTELEN);
} else {
stream_putc(s, 24);
stream_putl(s, 0); /* RD = 0, per RFC */
stream_putl(s, 0);
stream_put(s, &attr->mp_nexthop_global,
IPV6_MAX_BYTELEN);
}
} break;
case SAFI_ENCAP: