bgpd: keep interface index on bgp nexthop tracking

The following BGP configuration does not show that the
resolved next-hop to 192.0.2.1 has a defined interface.

> router bgp 65500
>  bgp router-id 192.0.2.2
>  neighbor 192.0.2.1 remote-as 65500
>  neighbor 192.0.2.1 update-source loop1
>  neighbor 192.168.0.1 remote-as 65500
>  !
>  address-family ipv4 unicast
>   network 192.0.2.2/32
>   no neighbor 192.168.0.1 activate
>  exit-address-family
>  !
>  address-family ipv4 labeled-unicast
>   neighbor 192.168.0.1 activate
>  exit-address-family
>  !
>  address-family ipv4 vpn
>   neighbor 192.0.2.1 activate
>  exit-address-family

The 'show bgp nexthop' dump does not output the interface
whereas the zebra rnh has the information.

> dut-vm# show bgp nexthop
> [..]
> Current BGP nexthop cache:
>  192.0.2.1 valid [IGP metric 0], #paths 1, peer 192.0.2.1
>   gate 192.168.0.1
>   Last update: Mon Apr 24 22:10:07 2023
>
> dut-vm# show ip nht
> 192.0.2.1
>  resolved via bgp
>  via 192.168.0.1, r2-eth0
>  Client list: bgp(fd 33)

Modify the display of BGP nexthop tracking to also dump
the interface used:

> dut-vm# show bgp nexthop
> [..]
> Current BGP nexthop cache:
>  192.0.2.1 valid [IGP metric 0], #paths 1, peer 192.0.2.1
>   gate 192.168.0.1, r2-eth0
>   Last update: Mon Apr 24 22:10:07 2023

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>

diff --git a/bgpd/bgp_nexthop.c b/bgpd/bgp_nexthop.c
index c4b832ee595eff58da20f20c75310bd1ce52ffc9..1c79d7d03be34ce8bea84cd64517500c71ec3c60 100644 (file)
--- a/bgpd/bgp_nexthop.c
+++ b/bgpd/bgp_nexthop.c
@@ -908,17 +908,34 @@ static void bgp_show_nexthops_detail(struct vty *vty, struct bgp *bgp,
                }
                switch (nexthop->type) {
                case NEXTHOP_TYPE_IPV6:
-                       vty_out(vty, "  gate %pI6\n", &nexthop->gate.ipv6);
-                       break;
                case NEXTHOP_TYPE_IPV6_IFINDEX:
-                       vty_out(vty, "  gate %pI6, if %s\n",
-                               &nexthop->gate.ipv6,
-                               ifindex2ifname(bnc->ifindex ? bnc->ifindex
-                                                           : nexthop->ifindex,
-                                              bgp->vrf_id));
+                       vty_out(vty, "  gate %pI6", &nexthop->gate.ipv6);
+                       if (nexthop->type == NEXTHOP_TYPE_IPV6_IFINDEX &&
+                           bnc->ifindex)
+                               vty_out(vty, ", if %s\n",
+                                       ifindex2ifname(bnc->ifindex,
+                                                      bgp->vrf_id));
+                       else if (nexthop->ifindex)
+                               vty_out(vty, ", if %s\n",
+                                       ifindex2ifname(nexthop->ifindex,
+                                                      bgp->vrf_id));
+                       else
+                               vty_out(vty, "\n");
                        break;
                case NEXTHOP_TYPE_IPV4:
-                       vty_out(vty, "  gate %pI4\n", &nexthop->gate.ipv4);
+               case NEXTHOP_TYPE_IPV4_IFINDEX:
+                       vty_out(vty, "  gate %pI4", &nexthop->gate.ipv4);
+                       if (nexthop->type == NEXTHOP_TYPE_IPV4_IFINDEX &&
+                           bnc->ifindex)
+                               vty_out(vty, ", if %s\n",
+                                       ifindex2ifname(bnc->ifindex,
+                                                      bgp->vrf_id));
+                       else if (nexthop->ifindex)
+                               vty_out(vty, ", if %s\n",
+                                       ifindex2ifname(nexthop->ifindex,
+                                                      bgp->vrf_id));
+                       else
+                               vty_out(vty, "\n");
                        break;
                case NEXTHOP_TYPE_IFINDEX:
                        vty_out(vty, "  if %s\n",
@@ -926,13 +943,6 @@ static void bgp_show_nexthops_detail(struct vty *vty, struct bgp *bgp,
                                                            : nexthop->ifindex,
                                               bgp->vrf_id));
                        break;
-               case NEXTHOP_TYPE_IPV4_IFINDEX:
-                       vty_out(vty, "  gate %pI4, if %s\n",
-                               &nexthop->gate.ipv4,
-                               ifindex2ifname(bnc->ifindex ? bnc->ifindex
-                                                           : nexthop->ifindex,
-                                              bgp->vrf_id));
-                       break;
                case NEXTHOP_TYPE_BLACKHOLE:
                        vty_out(vty, "  blackhole\n");
                        break;