bgpd: set nexthop self only for ebgp routes

Hi,

For a BGP route reflector setup I want to set next hop self
towards iBGP peers. But only for routes learnt through eBGP.

In the RIB I can see this:

dut# bgpctl sh rib det 172.0.42.0/24

BGP routing table entry for 172.0.42.0/24
Nexthop 10.100.0.10 (via 10.1.0.2) Neighbor r1 (10.100.0.10)
Origin IGP, metric 0, localpref 100, weight 0, ovs not-found, avs unknown, internal, valid, best
^^^^^^^^
Last update: 00:58:22 ago
Originator Id: 10.100.0.10
Cluster Id List: 10.0.0.42

BGP routing table entry for 172.0.42.0/24
Nexthop 10.100.0.10 (via 10.1.0.2) Neighbor rr2 (10.100.0.2)
Origin IGP, metric 0, localpref 100, weight 0, ovs not-found, avs unknown, internal, valid, ecmp
^^^^^^^^
Last update: 00:58:24 ago
Originator Id: 10.100.0.10
Cluster Id List: 10.0.0.42 10.0.0.43

BGP routing table entry for 172.0.42.0/24
65101 65000
Nexthop 10.1.0.14 (via 10.1.0.14) Neighbor x1 (172.42.42.1)
Origin IGP, metric 0, localpref 100, weight 0, ovs not-found, avs unknown, external
^^^^^^^^
Last update: 00:58:24 ago
Originator Id: 10.100.0.1
Cluster Id List: 10.0.0.42
dut#

With "set nexthop self" for a given neighbor the nexthop is changed
unconditinally for this neighbor. How can I match only on external
routes?

Remi