bgpd: auto router-id should not change configured vpn RD/RT

A router-id change that isn't explicitly configured (a change
from zebra, for example) should not replace a configured vpn
RD/RT.

Signed-off-by: Mark Stapp <mjs@voltanet.io>

3 files changed, 32 insertions, 10 deletions

diff --git a/bgpd/bgp_mplsvpn.c b/bgpd/bgp_mplsvpn.c
index 6eddd0e1e3..355bc93320 100644
--- a/bgpd/bgp_mplsvpn.c
+++ b/bgpd/bgp_mplsvpn.c
@@ -1488,7 +1488,8 @@ static void vpn_policy_routemap_update(struct bgp *bgp, const char *rmap_name)
 /* This API is used during router-id change, reflect VPNs
  * auto RD and RT values and readvertise routes to VPN table.
  */
-void vpn_handle_router_id_update(struct bgp *bgp, bool withdraw)
+void vpn_handle_router_id_update(struct bgp *bgp, bool withdraw,
+				 bool is_config)
 {
 	afi_t afi;
 	int debug;
@@ -1536,6 +1537,20 @@ void vpn_handle_router_id_update(struct bgp *bgp, bool withdraw)
 
 			}
 		} else {
+			/*
+			 * Router-id changes that are not explicit config
+			 * changes should not replace configured RD/RT.
+			 */
+			if (!is_config) {
+				if (CHECK_FLAG(bgp->vpn_policy[afi].flags,
+					       BGP_VPN_POLICY_TOVPN_RD_SET)) {
+					if (debug)
+						zlog_debug("%s: auto router-id change skipped",
+							   __func__);
+					goto postchange;
+				}
+			}
+
 			/* New router-id derive auto RD and RT and export
 			 * to VPN
 			 */
@@ -1565,6 +1580,8 @@ void vpn_handle_router_id_update(struct bgp *bgp, bool withdraw)
 						= ecommunity_dup(ecom);
 
 			}
+
+postchange:
 			/* Update routes to VPN */
 			vpn_leak_postchange(BGP_VPN_POLICY_DIR_TOVPN,
 					    afi, bgp_get_default(),
diff --git a/bgpd/bgp_mplsvpn.h b/bgpd/bgp_mplsvpn.h
index 1526a8111e..2a6c0e1708 100644
--- a/bgpd/bgp_mplsvpn.h
+++ b/bgpd/bgp_mplsvpn.h
@@ -264,6 +264,7 @@ extern void vpn_policy_routemap_event(const char *rmap_name);
 extern vrf_id_t get_first_vrf_for_redirect_with_rt(struct ecommunity *eckey);
 
 extern void vpn_leak_postchange_all(void);
-extern void vpn_handle_router_id_update(struct bgp *bgp, bool withdraw);
+extern void vpn_handle_router_id_update(struct bgp *bgp, bool withdraw,
+					bool is_config);
 
 #endif /* _QUAGGA_BGP_MPLSVPN_H */
diff --git a/bgpd/bgpd.c b/bgpd/bgpd.c
index 02eda7a430..65f1b64820 100644
--- a/bgpd/bgpd.c
+++ b/bgpd/bgpd.c
@@ -234,8 +234,11 @@ static int bgp_config_check(struct bgp *bgp, int config)
 	return CHECK_FLAG(bgp->config, config);
 }
 
-/* Set BGP router identifier. */
-static int bgp_router_id_set(struct bgp *bgp, const struct in_addr *id)
+/* Set BGP router identifier; distinguish between explicit config and other
+ * cases.
+ */
+static int bgp_router_id_set(struct bgp *bgp, const struct in_addr *id,
+			     bool is_config)
 {
 	struct peer *peer;
 	struct listnode *node, *nnode;
@@ -247,7 +250,7 @@ static int bgp_router_id_set(struct bgp *bgp, const struct in_addr *id)
 	if (is_evpn_enabled())
 		bgp_evpn_handle_router_id_update(bgp, TRUE);
 
-	vpn_handle_router_id_update(bgp, TRUE);
+	vpn_handle_router_id_update(bgp, TRUE, is_config);
 
 	IPV4_ADDR_COPY(&bgp->router_id, id);
 
@@ -266,7 +269,7 @@ static int bgp_router_id_set(struct bgp *bgp, const struct in_addr *id)
 	if (is_evpn_enabled())
 		bgp_evpn_handle_router_id_update(bgp, FALSE);
 
-	vpn_handle_router_id_update(bgp, FALSE);
+	vpn_handle_router_id_update(bgp, FALSE, is_config);
 
 	return 0;
 }
@@ -300,7 +303,7 @@ void bgp_router_id_zebra_bump(vrf_id_t vrf_id, const struct prefix *router_id)
 					if (BGP_DEBUG(zebra, ZEBRA))
 						zlog_debug("RID change : vrf %u, RTR ID %s",
 					bgp->vrf_id, inet_ntoa(*addr));
-					bgp_router_id_set(bgp, addr);
+					bgp_router_id_set(bgp, addr, FALSE);
 				}
 			}
 		}
@@ -320,7 +323,7 @@ void bgp_router_id_zebra_bump(vrf_id_t vrf_id, const struct prefix *router_id)
 					if (BGP_DEBUG(zebra, ZEBRA))
 						zlog_debug("RID change : vrf %u, RTR ID %s",
 					bgp->vrf_id, inet_ntoa(*addr));
-					bgp_router_id_set(bgp, addr);
+					bgp_router_id_set(bgp, addr, FALSE);
 				}
 			}
 
@@ -331,7 +334,8 @@ void bgp_router_id_zebra_bump(vrf_id_t vrf_id, const struct prefix *router_id)
 int bgp_router_id_static_set(struct bgp *bgp, struct in_addr id)
 {
 	bgp->router_id_static = id;
-	bgp_router_id_set(bgp, id.s_addr ? &id : &bgp->router_id_zebra);
+	bgp_router_id_set(bgp, id.s_addr ? &id : &bgp->router_id_zebra,
+			  TRUE /* is config */);
 	return 0;
 }
 
@@ -3185,7 +3189,7 @@ int bgp_get(struct bgp **bgp_val, as_t *as, const char *name,
 	bgp = bgp_create(as, name, inst_type);
 	if (bgp_option_check(BGP_OPT_NO_ZEBRA) && name)
 		bgp->vrf_id = vrf_generate_id();
-	bgp_router_id_set(bgp, &bgp->router_id_zebra);
+	bgp_router_id_set(bgp, &bgp->router_id_zebra, TRUE);
 	bgp_address_init(bgp);
 	bgp_tip_hash_init(bgp);
 	bgp_scan_init(bgp);