Track Route Reflection Cluster IDs within the VRF scope

  To make sure we don't have any Cluster list loops we need to check all the
  Cluster IDs used by all sessions within a VRF as in theory there could be
  multiple iBGP sessions with different cluster IDs set.

Signed-off-by: Maximilian Wilhelm <max@sdn.clinic>

protocols/bgp/server/fsm_address_family.go

@@ -95,6 +95,9 @@ func (f *fsmAddressFamily) init() {
 
 	f.adjRIBIn = f.fsm.peer.adjRIBInFactory.New(f.importFilterChain, f.fsm.peer.vrf, sessionAttrs)
 	f.fsm.peer.vrf.AddContributingASN(f.fsm.peer.localASN)
+	if f.fsm.peer.routeReflectorClient {
+		f.fsm.peer.vrf.AddContributingClusterID(f.fsm.peer.clusterID)
+	}
 
 	f.adjRIBIn.Register(f.rib)
 
@@ -163,6 +166,10 @@ func (f *fsmAddressFamily) dispose() {
 	}
 
 	f.fsm.peer.vrf.RemoveContributingASN(f.fsm.peer.localASN)
+	if f.fsm.peer.routeReflectorClient {
+		f.fsm.peer.vrf.RemoveContributingClusterID(f.fsm.peer.clusterID)
+	}
+
 	f.adjRIBIn.Unregister(f.rib)
 	f.rib.Unregister(f.adjRIBOut)
 	f.adjRIBOut.Unregister(f.updateSender)

routingtable/adjRIBIn/adj_rib_in.go

@@ -296,10 +296,10 @@ func (a *AdjRIBIn) validatePath(p *route.Path) uint8 {
 		return route.HiddenReasonOurOriginatorID
 	}
 
-	// RFC4456 Sect. 8: Ignore routes which contain our ClusterID in their ClusterList
+	// RFC4456 Sect. 8: Ignore routes which contains any ClusterID used within this VRF in their ClusterList
 	if p.BGPPath.ClusterList != nil && len(*p.BGPPath.ClusterList) > 0 {
 		for _, cid := range *p.BGPPath.ClusterList {
-			if cid == a.sessionAttrs.ClusterID {
+			if a.vrf.IsContributingClusterID(cid) {
 				return route.HiddenReasonClusterLoop
 			}
 		}

routingtable/adjRIBIn/adj_rib_in_test.go

@@ -266,7 +266,9 @@ func TestAddPath(t *testing.T) {
 			ClusterID: clusterID,
 			AddPathRX: test.addPath,
 		}
-		adjRIBIn := New(filter.NewAcceptAllFilterChain(), vrf.NewUntrackedVRF("vrf0", 0), sessionAttrs)
+		vrf := vrf.NewUntrackedVRF("vrf0", 0)
+		vrf.AddContributingClusterID(clusterID)
+		adjRIBIn := New(filter.NewAcceptAllFilterChain(), vrf, sessionAttrs)
 		mc := routingtable.NewRTMockClient()
 		adjRIBIn.clientManager.RegisterWithOptions(mc, routingtable.ClientOptions{BestOnly: true})
 

routingtable/vrf/vrf.go

@@ -23,12 +23,13 @@ type addressFamily struct {
 
 // VRF a list of RIBs for different address families building a routing instance
 type VRF struct {
-	name               string
-	routeDistinguisher uint64
-	ribs               map[addressFamily]*locRIB.LocRIB
-	mu                 sync.Mutex
-	ribNames           map[string]*locRIB.LocRIB
-	contributingASNs   *refcounter.RefcounterUint32
+	name                   string
+	routeDistinguisher     uint64
+	ribs                   map[addressFamily]*locRIB.LocRIB
+	mu                     sync.Mutex
+	ribNames               map[string]*locRIB.LocRIB
+	contributingASNs       *refcounter.RefcounterUint32
+	contributingClusterIDs *refcounter.RefcounterUint32
 }
 
 // New creates a new VRF. The VRF is registered automatically to the global VRF registry.
@@ -47,11 +48,12 @@ func New(name string, rd uint64) (*VRF, error) {
 
 func NewUntrackedVRF(name string, rd uint64) *VRF {
 	return &VRF{
-		name:               name,
-		routeDistinguisher: rd,
-		ribs:               make(map[addressFamily]*locRIB.LocRIB),
-		ribNames:           make(map[string]*locRIB.LocRIB),
-		contributingASNs:   refcounter.NewRefCounterUint32(),
+		name:                   name,
+		routeDistinguisher:     rd,
+		ribs:                   make(map[addressFamily]*locRIB.LocRIB),
+		ribNames:               make(map[string]*locRIB.LocRIB),
+		contributingASNs:       refcounter.NewRefCounterUint32(),
+		contributingClusterIDs: refcounter.NewRefCounterUint32(),
 	}
 }
 
@@ -137,6 +139,21 @@ func (v *VRF) IsContributingASN(asn uint32) bool {
 	return v.contributingASNs.IsPresent(asn)
 }
 
+// AddContributingASN adds the given ClusterID to the list of ClusterIDs is used by this BGP speaker somewhere within this VRF
+func (v *VRF) AddContributingClusterID(cid uint32) {
+	v.contributingClusterIDs.Add(cid)
+}
+
+// RemoveContributingASN removes the given ClusterID from the list of ClusterIDs is used by this BGP speaker somewhere within this VRF
+func (v *VRF) RemoveContributingClusterID(cid uint32) {
+	v.contributingClusterIDs.Remove(cid)
+}
+
+// IsContributingASN returns wether the given ClusterID is used by this BGP speaker somewhere within this VRF
+func (v *VRF) IsContributingClusterID(cid uint32) bool {
+	return v.contributingClusterIDs.IsPresent(cid)
+}
+
 func (v *VRF) nameForRIB(rib *locRIB.LocRIB) string {
 	for name, r := range v.ribNames {
 		if r == rib {