bgpd: Fix peer withdrawal and route leaking for vpn's and vrf's

When a peer is removed the routes are withdrawn via bgp_process_main_one
As such we need to put a bit of code in to handle this situation
for the vpn/vrf route leaking code.

I think this code path is also called for when a vrf's route is
changed and I believe we will end up putting a bit more code
here to handle the nexthop changes.

I've also started trying to document the bgp_process_main_one
function a bit better.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>

diff --git a/bgpd/bgp_route.c b/bgpd/bgp_route.c
index 35732d1bf5bc842642008dd6ec192b0a3cf5b342..5e122efe8f9885569ea2853bfe513669a5eba89a 100644 (file)
--- a/bgpd/bgp_route.c
+++ b/bgpd/bgp_route.c
@@ -2095,6 +2095,25 @@ struct bgp_process_queue {
        unsigned int queued;
 };
 
+/*
+ * old_select = The old best path
+ * new_select = the new best path
+ *
+ * if (!old_select && new_select)
+ *     We are sending new information on.
+ *
+ * if (old_select && new_select) {
+ *         if (new_select != old_select)
+ *                 We have a new best path send a change
+ *         else
+ *                 We've received a update with new attributes that needs
+ *                 to be passed on.
+ * }
+ *
+ * if (old_select && !new_select)
+ *     We have no eligible route that we can announce or the rn
+ *     is being removed.
+ */
 static void bgp_process_main_one(struct bgp *bgp, struct bgp_node *rn,
                                 afi_t afi, safi_t safi)
 {
@@ -3664,10 +3683,12 @@ static wq_item_status bgp_clear_route_node(struct work_queue *wq, void *data)
        struct bgp_node *rn = cnq->rn;
        struct peer *peer = wq->spec.data;
        struct bgp_info *ri;
+       struct bgp *bgp;
        afi_t afi = bgp_node_table(rn)->afi;
        safi_t safi = bgp_node_table(rn)->safi;
 
        assert(rn && peer);
+       bgp = peer->bgp;
 
        /* It is possible that we have multiple paths for a prefix from a peer
         * if that peer is using AddPath.
@@ -3686,8 +3707,18 @@ static wq_item_status bgp_clear_route_node(struct work_queue *wq, void *data)
                        /* If this is an EVPN route, process for
                         * un-import. */
                        if (safi == SAFI_EVPN)
-                               bgp_evpn_unimport_route(peer->bgp, afi, safi,
+                               bgp_evpn_unimport_route(bgp, afi, safi,
                                                        &rn->p, ri);
+                       /* Handle withdraw for VRF route-leaking and L3VPN */
+                       if (SAFI_UNICAST == safi
+                           && (bgp->inst_type == BGP_INSTANCE_TYPE_VRF ||
+                               bgp->inst_type == BGP_INSTANCE_TYPE_DEFAULT))
+                               vpn_leak_from_vrf_withdraw(bgp_get_default(),
+                                                          bgp, ri);
+                       if (SAFI_MPLS_VPN == safi &&
+                           bgp->inst_type == BGP_INSTANCE_TYPE_DEFAULT)
+                               vpn_leak_to_vrf_withdraw(bgp, ri);
+
                        bgp_rib_remove(rn, ri, peer, afi, safi);
                }
        }