BMP: Support pre policy monitoring (#336)

protocols/bgp/server/bmp_router.go

@@ -181,7 +181,8 @@ func (r *Router) processRouteMonitoringMsg(msg *bmppkt.RouteMonitoringMsg) {
 	s := n.fsm.state.(*establishedState)
 	opt := s.fsm.decodeOptions()
 	opt.Use32BitASN = !msg.PerPeerHeader.GetAFlag()
-	s.msgReceived(msg.BGPUpdate, opt)
+
+	s.msgReceived(msg.BGPUpdate, opt, msg.PerPeerHeader.GetLFlag())
 }
 
 func (r *Router) processInitiationMsg(msg *bmppkt.InitiationMessage) {

protocols/bgp/server/fsm_address_family.go

@@ -143,27 +143,30 @@ func (f *fsmAddressFamily) dispose() {
 	f.initialized = false
 }
 
-func (f *fsmAddressFamily) processUpdate(u *packet.BGPUpdate) {
+func (f *fsmAddressFamily) processUpdate(u *packet.BGPUpdate, postPolicy bool) {
 	if f.safi != packet.SAFIUnicast {
 		return
 	}
 
 	f.multiProtocolUpdates(u)
 	if f.afi == packet.AFIIPv4 {
-		f.withdraws(u)
-		f.updates(u)
+		f.withdraws(u, postPolicy)
+		f.updates(u, postPolicy)
 	}
 }
 
-func (f *fsmAddressFamily) withdraws(u *packet.BGPUpdate) {
+func (f *fsmAddressFamily) withdraws(u *packet.BGPUpdate, postPolicy bool) {
 	for r := u.WithdrawnRoutes; r != nil; r = r.Next {
-		f.adjRIBIn.RemovePath(r.Prefix, nil)
+		f.adjRIBIn.RemovePath(r.Prefix, &route.Path{
+			PostPolicy: postPolicy,
+		})
 	}
 }
 
-func (f *fsmAddressFamily) updates(u *packet.BGPUpdate) {
+func (f *fsmAddressFamily) updates(u *packet.BGPUpdate, postPolicy bool) {
 	for r := u.NLRI; r != nil; r = r.Next {
 		path := f.newRoutePath()
+		path.PostPolicy = postPolicy
 		f.processAttributes(u.PathAttributes, path)
 
 		f.adjRIBIn.AddPath(r.Prefix, path)

protocols/bgp/server/fsm_established.go

@@ -51,7 +51,7 @@ func (s establishedState) run() (state, string) {
 		case <-time.After(time.Second):
 			return s.checkHoldtimer()
 		case recvMsg := <-s.fsm.msgRecvCh:
-			return s.msgReceived(recvMsg, opt)
+			return s.msgReceived(recvMsg, opt, false)
 		}
 	}
 }
@@ -159,7 +159,7 @@ func (s *establishedState) keepaliveTimerExpired() (state, string) {
 	return newEstablishedState(s.fsm), s.fsm.reason
 }
 
-func (s *establishedState) msgReceived(data []byte, opt *packet.DecodeOptions) (state, string) {
+func (s *establishedState) msgReceived(data []byte, opt *packet.DecodeOptions, postPolicy bool) (state, string) {
 	msg, err := packet.Decode(bytes.NewBuffer(data), opt)
 	if err != nil {
 		switch bgperr := err.(type) {
@@ -179,7 +179,7 @@ func (s *establishedState) msgReceived(data []byte, opt *packet.DecodeOptions) (
 		fmt.Println(data)
 		return s.notification()
 	case packet.UpdateMsg:
-		return s.update(msg.Body.(*packet.BGPUpdate))
+		return s.update(msg.Body.(*packet.BGPUpdate), postPolicy)
 	case packet.KeepaliveMsg:
 		return s.keepaliveReceived()
 	default:
@@ -195,19 +195,19 @@ func (s *establishedState) notification() (state, string) {
 	return newIdleState(s.fsm), "Received NOTIFICATION"
 }
 
-func (s *establishedState) update(u *packet.BGPUpdate) (state, string) {
+func (s *establishedState) update(u *packet.BGPUpdate, postPolicy bool) (state, string) {
 	atomic.AddUint64(&s.fsm.counters.updatesReceived, 1)
 
 	if s.fsm.holdTime != 0 {
 		s.fsm.updateLastUpdateOrKeepalive()
 	}
 
 	if s.fsm.ipv4Unicast != nil {
-		s.fsm.ipv4Unicast.processUpdate(u)
+		s.fsm.ipv4Unicast.processUpdate(u, postPolicy)
 	}
 
 	if s.fsm.ipv6Unicast != nil {
-		s.fsm.ipv6Unicast.processUpdate(u)
+		s.fsm.ipv6Unicast.processUpdate(u, postPolicy)
 	}
 
 	afi, safi := s.updateAddressFamily(u)

protocols/bmp/packet/per_peer_header.go

@@ -67,6 +67,11 @@ func (p *PerPeerHeader) GetIPVersion() uint8 {
 	return 4
 }
 
+// GetLFlag checks if the L flag is set
+func (p *PerPeerHeader) GetLFlag() bool {
+	return p.PeerFlags&0b01000000 == 0b01000000
+}
+
 // GetAFlag checks if the A flag is set
 func (p *PerPeerHeader) GetAFlag() bool {
 	return p.PeerFlags&0b00100000 == 0b00100000

route/path.go

@@ -10,6 +10,7 @@ import (
 // Path represents a network path
 type Path struct {
 	Type       uint8
+	PostPolicy bool // PostPolicy fields is a hack used in BMP to differentiate between pre/post policy routes (L flag of the per peer header)
 	StaticPath *StaticPath
 	BGPPath    *BGPPath
 	FIBPath    *FIBPath