bgpd: bgpd-set-v4-nexthop-for-v6-peering.patch
BGP: While advertising v4 prefixes over a v6 session, set the correct v4 nexthop.
ISSUE:
For an IPv6 peer, BGPd sets the local router-id as the next-hop's v4 address.
This is incorrect as the router-id may not be a valid next-hop to be included
in UPDATEs that contain v4 prefixes.
PATCH:
Set the v4 address in the next-hop field based on the interface that the
peering is on (directly connected interface or loopback).
Signed-off-by: Pradosh Mohapatra <pmohapat at cumulusnetworks.com>
Reviewed-by: Scott Feldman <sfeldma at cumulusnetworks.com>
Acked-by: Feng Lu <lu.feng@6wind.com>
diff --git a/bgpd/bgp_zebra.c b/bgpd/bgp_zebra.c
index 6044383..26b97c2 100644
--- a/bgpd/bgp_zebra.c
+++ b/bgpd/bgp_zebra.c
@@ -534,6 +534,25 @@
}
#endif /* HAVE_IPV6 */
+static int
+if_get_ipv4_address (struct interface *ifp, struct in_addr *addr)
+{
+ struct listnode *cnode;
+ struct connected *connected;
+ struct prefix *cp;
+
+ for (ALL_LIST_ELEMENTS_RO (ifp->connected, cnode, connected))
+ {
+ cp = connected->address;
+ if ((cp->family == AF_INET) && !ipv4_martian(&(cp->u.prefix4)))
+ {
+ *addr = cp->u.prefix4;
+ return 1;
+ }
+ }
+ return 0;
+}
+
int
bgp_nexthop_set (union sockunion *local, union sockunion *remote,
struct bgp_nexthop *nexthop, struct peer *peer)
@@ -592,8 +611,9 @@
{
struct interface *direct = NULL;
- /* IPv4 nexthop. I don't care about it. */
- if (peer->local_id.s_addr)
+ /* IPv4 nexthop. */
+ ret = if_get_ipv4_address(ifp, &nexthop->v4);
+ if (!ret && peer->local_id.s_addr)
nexthop->v4 = peer->local_id;
/* Global address*/