Supporting BGP/MPLS L3VPNs with Frrouting Zebra API 6

 - This commit aims to solve reported problem on issues #1611, #1648 and #1912
 - Partial changes of this commit duplicate with changes on PR #1587 (not merged) and PR #1766 (not merged and already closed)
 - This commit is tested with only FRRouting version 6.0.2 (which uses Zebra API 6)
 - This commit fixes lack of LABEL_MANAGER_CONNECT_ASYNC for ZAPI6.
   (This bug is introduced on commit 2bdb76f2dcf24b891f2b6327a57c31b26463b2dd "Supporting Zebra API version 6 which is used in FRRouting version 6")

3 files changed, 105 insertions, 31 deletions

diff --git a/internal/pkg/table/path.go b/internal/pkg/table/path.go
index eba0a6ec..bdeb6ff2 100644
--- a/internal/pkg/table/path.go
+++ b/internal/pkg/table/path.go
@@ -133,13 +133,14 @@ type Validation struct {
 }
 
 type Path struct {
-	info      *originInfo
-	parent    *Path
-	pathAttrs []bgp.PathAttributeInterface
-	dels      []bgp.BGPAttrType
-	attrsHash uint32
-	aslooped  bool
-	reason    BestPathReason
+	info         *originInfo
+	parent       *Path
+	pathAttrs    []bgp.PathAttributeInterface
+	dels         []bgp.BGPAttrType
+	attrsHash    uint32
+	aslooped     bool
+	reason       BestPathReason
+	receiveVrfId uint32 //VRF in which the path was received.
 
 	// For BGP Nexthop Tracking, this field shows if nexthop is invalidated by IGP.
 	IsNexthopInvalid bool
@@ -167,8 +168,9 @@ func NewPath(source *PeerInfo, nlri bgp.AddrPrefixInterface, isWithdraw bool, pa
 			timestamp:          timestamp.Unix(),
 			noImplicitWithdraw: noImplicitWithdraw,
 		},
-		IsWithdraw: isWithdraw,
-		pathAttrs:  pattrs,
+		IsWithdraw:   isWithdraw,
+		pathAttrs:    pattrs,
+		receiveVrfId: 0,
 	}
 }
 
@@ -332,6 +334,13 @@ func (path *Path) IsIBGP() bool {
 	return (as == path.GetSource().LocalAS) && as != 0
 }
 
+func (path *Path) ReceiveVrfId() uint32 {
+	return path.receiveVrfId
+}
+func (path *Path) SetReceiveVrfId(vrfId uint32) {
+	path.receiveVrfId = vrfId
+}
+
 // create new PathAttributes
 func (path *Path) Clone(isWithdraw bool) *Path {
 	return &Path{
@@ -339,6 +348,7 @@ func (path *Path) Clone(isWithdraw bool) *Path {
 		IsWithdraw:       isWithdraw,
 		IsNexthopInvalid: path.IsNexthopInvalid,
 		attrsHash:        path.attrsHash,
+		receiveVrfId:     path.receiveVrfId,
 	}
 }
 
@@ -580,6 +590,7 @@ func (path *Path) String() string {
 	if path.IsWithdraw {
 		s.WriteString(", withdraw")
 	}
+	s.WriteString(fmt.Sprintf(", receiveVrfId: %d", path.receiveVrfId))
 	s.WriteString(" }")
 	return s.String()
 }
@@ -1069,12 +1080,12 @@ func (v *Vrf) ToGlobalPath(path *Path) error {
 	case bgp.RF_IPv4_UC:
 		n := nlri.(*bgp.IPAddrPrefix)
 		pathIdentifier := path.GetNlri().PathIdentifier()
-		path.OriginInfo().nlri = bgp.NewLabeledVPNIPAddrPrefix(n.Length, n.Prefix.String(), *bgp.NewMPLSLabelStack(0), v.Rd)
+		path.OriginInfo().nlri = bgp.NewLabeledVPNIPAddrPrefix(n.Length, n.Prefix.String(), *bgp.NewMPLSLabelStack(v.MplsLabel), v.Rd)
 		path.GetNlri().SetPathIdentifier(pathIdentifier)
 	case bgp.RF_IPv6_UC:
 		n := nlri.(*bgp.IPv6AddrPrefix)
 		pathIdentifier := path.GetNlri().PathIdentifier()
-		path.OriginInfo().nlri = bgp.NewLabeledVPNIPv6AddrPrefix(n.Length, n.Prefix.String(), *bgp.NewMPLSLabelStack(0), v.Rd)
+		path.OriginInfo().nlri = bgp.NewLabeledVPNIPv6AddrPrefix(n.Length, n.Prefix.String(), *bgp.NewMPLSLabelStack(v.MplsLabel), v.Rd)
 		path.GetNlri().SetPathIdentifier(pathIdentifier)
 	case bgp.RF_EVPN:
 		n := nlri.(*bgp.EVPNNLRI)
@@ -1098,11 +1109,11 @@ func (p *Path) ToGlobal(vrf *Vrf) *Path {
 	switch rf := p.GetRouteFamily(); rf {
 	case bgp.RF_IPv4_UC:
 		n := nlri.(*bgp.IPAddrPrefix)
-		nlri = bgp.NewLabeledVPNIPAddrPrefix(n.Length, n.Prefix.String(), *bgp.NewMPLSLabelStack(0), vrf.Rd)
+		nlri = bgp.NewLabeledVPNIPAddrPrefix(n.Length, n.Prefix.String(), *bgp.NewMPLSLabelStack(vrf.MplsLabel), vrf.Rd)
 		nlri.SetPathIdentifier(pathId)
 	case bgp.RF_IPv6_UC:
 		n := nlri.(*bgp.IPv6AddrPrefix)
-		nlri = bgp.NewLabeledVPNIPv6AddrPrefix(n.Length, n.Prefix.String(), *bgp.NewMPLSLabelStack(0), vrf.Rd)
+		nlri = bgp.NewLabeledVPNIPv6AddrPrefix(n.Length, n.Prefix.String(), *bgp.NewMPLSLabelStack(vrf.MplsLabel), vrf.Rd)
 		nlri.SetPathIdentifier(pathId)
 	case bgp.RF_EVPN:
 		n := nlri.(*bgp.EVPNNLRI)
@@ -1138,6 +1149,7 @@ func (p *Path) ToGlobal(vrf *Vrf) *Path {
 	path.delPathAttr(bgp.BGP_ATTR_TYPE_NEXT_HOP)
 	path.setPathAttr(bgp.NewPathAttributeMpReachNLRI(nh.String(), []bgp.AddrPrefixInterface{nlri}))
 	path.IsNexthopInvalid = p.IsNexthopInvalid
+	path.receiveVrfId = p.receiveVrfId
 	return path
 }
 
diff --git a/internal/pkg/table/table_manager.go b/internal/pkg/table/table_manager.go
index 58c09bf3..45698504 100644
--- a/internal/pkg/table/table_manager.go
+++ b/internal/pkg/table/table_manager.go
@@ -105,9 +105,10 @@ func ProcessMessage(m *bgp.BGPMessage, peerInfo *PeerInfo, timestamp time.Time)
 }
 
 type TableManager struct {
-	Tables map[bgp.RouteFamily]*Table
-	Vrfs   map[string]*Vrf
-	rfList []bgp.RouteFamily
+	Tables        map[bgp.RouteFamily]*Table
+	Vrfs          map[string]*Vrf
+	rfList        []bgp.RouteFamily
+	mplsLabelMaps map[uint64]*Bitmap
 }
 
 func NewTableManager(rfList []bgp.RouteFamily) *TableManager {
@@ -122,6 +123,63 @@ func NewTableManager(rfList []bgp.RouteFamily) *TableManager {
 	return t
 }
 
+func (manager *TableManager) EnableMplsLabelAllocation() error {
+	if manager.mplsLabelMaps != nil {
+		return fmt.Errorf("label allocation already enabled")
+	}
+	manager.mplsLabelMaps = make(map[uint64]*Bitmap)
+	return nil
+}
+
+func (manager *TableManager) AllocateMplsLabelRange(start, end uint32) error {
+	if manager.mplsLabelMaps == nil {
+		return fmt.Errorf("label allocation not yet enabled")
+	}
+	log.WithFields(log.Fields{
+		"Topic": "Vrf",
+		"Start": start,
+		"End":   end,
+	}).Debug("allocate new MPLS label range")
+	startEnd := uint64(start)<<32 | uint64(end)
+	manager.mplsLabelMaps[startEnd] = NewBitmap(int(end - start + 1))
+	return nil
+}
+
+func (manager *TableManager) AssignMplsLabel() (uint32, error) {
+	if manager.mplsLabelMaps == nil {
+		return 0, nil
+	}
+	var label uint32
+	for startEnd, bitmap := range manager.mplsLabelMaps {
+		start := uint32(startEnd >> 32)
+		end := uint32(startEnd & 0xffffffff)
+		l, err := bitmap.FindandSetZeroBit()
+		if err == nil && start+uint32(l) <= end {
+			label = start + uint32(l)
+			break
+		}
+	}
+	if label == 0 {
+		return 0, fmt.Errorf("could not assign new MPLS label; need to allocate new MPLS label range")
+	}
+	return label, nil
+}
+
+func (manager *TableManager) releaseMplsLabel(label uint32) {
+	if manager.mplsLabelMaps == nil {
+		return
+	}
+	for startEnd, bitmap := range manager.mplsLabelMaps {
+		start := uint32(startEnd >> 32)
+		end := uint32(startEnd & 0xffffffff)
+		if start <= label && label <= end {
+			bitmap.Unflag(uint(label - start))
+			return
+		}
+	}
+	return
+}
+
 func (manager *TableManager) GetRFlist() []bgp.RouteFamily {
 	return manager.rfList
 }
@@ -166,12 +224,14 @@ func (manager *TableManager) DeleteVrf(name string) ([]*Path, error) {
 		msgs = append(msgs, t.deletePathsByVrf(vrf)...)
 	}
 	log.WithFields(log.Fields{
-		"Topic":    "Vrf",
-		"Key":      vrf.Name,
-		"Rd":       vrf.Rd,
-		"ImportRt": vrf.ImportRt,
-		"ExportRt": vrf.ExportRt,
+		"Topic":     "Vrf",
+		"Key":       vrf.Name,
+		"Rd":        vrf.Rd,
+		"ImportRt":  vrf.ImportRt,
+		"ExportRt":  vrf.ExportRt,
+		"MplsLabel": vrf.MplsLabel,
 	}).Debugf("delete vrf")
+	manager.releaseMplsLabel(vrf.MplsLabel)
 	delete(manager.Vrfs, name)
 	rtcTable := manager.Tables[bgp.RF_RTC_UC]
 	msgs = append(msgs, rtcTable.deleteRTCPathsByVrf(vrf, manager.Vrfs)...)
diff --git a/internal/pkg/table/vrf.go b/internal/pkg/table/vrf.go
index 053f85ce..dc98e57d 100644
--- a/internal/pkg/table/vrf.go
+++ b/internal/pkg/table/vrf.go
@@ -20,11 +20,12 @@ import (
 )
 
 type Vrf struct {
-	Name     string
-	Id       uint32
-	Rd       bgp.RouteDistinguisherInterface
-	ImportRt []bgp.ExtendedCommunityInterface
-	ExportRt []bgp.ExtendedCommunityInterface
+	Name      string
+	Id        uint32
+	Rd        bgp.RouteDistinguisherInterface
+	ImportRt  []bgp.ExtendedCommunityInterface
+	ExportRt  []bgp.ExtendedCommunityInterface
+	MplsLabel uint32
 }
 
 func (v *Vrf) Clone() *Vrf {
@@ -33,11 +34,12 @@ func (v *Vrf) Clone() *Vrf {
 		return append(l, rt...)
 	}
 	return &Vrf{
-		Name:     v.Name,
-		Id:       v.Id,
-		Rd:       v.Rd,
-		ImportRt: f(v.ImportRt),
-		ExportRt: f(v.ExportRt),
+		Name:      v.Name,
+		Id:        v.Id,
+		Rd:        v.Rd,
+		ImportRt:  f(v.ImportRt),
+		ExportRt:  f(v.ExportRt),
+		MplsLabel: v.MplsLabel,
 	}
 }