*: Support BGP Confederations (RFC 5065)

Signed-off-by: Satoshi Fujimoto <satoshi.fujimoto7@gmail.com>

4 files changed, 48 insertions, 15 deletions

diff --git a/table/destination.go b/table/destination.go
index 9631fc1c..5de89321 100644
--- a/table/destination.go
+++ b/table/destination.go
@@ -92,6 +92,7 @@ type PeerInfo struct {
 	RouteReflectorClient    bool
 	RouteReflectorClusterID net.IP
 	MultihopTtl             uint8
+	Confederation           bool
 }
 
 func (lhs *PeerInfo) Equal(rhs *PeerInfo) bool {
@@ -136,6 +137,7 @@ func NewPeerInfo(g *config.Global, p *config.Neighbor) *PeerInfo {
 		Address:                 naddr.IP,
 		RouteReflectorClusterID: id,
 		MultihopTtl:             p.EbgpMultihop.Config.MultihopTtl,
+		Confederation:           p.IsConfederationMember(g),
 	}
 }
 
@@ -892,9 +894,12 @@ func compareByASNumber(path1, path2 *Path) *Path {
 	log.WithFields(log.Fields{
 		"Topic": "Table",
 	}).Debugf("compareByASNumber -- p1Asn: %d, p2Asn: %d", path1.GetSource().AS, path2.GetSource().AS)
-	// If one path is from ibgp peer and another is from ebgp peer, take the ebgp path
-	if path1.IsIBGP() != path2.IsIBGP() {
-		if path1.IsIBGP() {
+	// Path from confederation member should be treated as internal (IBGP learned) path.
+	isIBGP1 := path1.GetSource().Confederation || path1.IsIBGP()
+	isIBGP2 := path2.GetSource().Confederation || path2.IsIBGP()
+	// If one path is from ibgp peer and another is from ebgp peer, take the ebgp path.
+	if isIBGP1 != isIBGP2 {
+		if isIBGP1 {
 			return path2
 		}
 		return path1
diff --git a/table/path.go b/table/path.go
index e192a770..d6f6e217 100644
--- a/table/path.go
+++ b/table/path.go
@@ -268,7 +268,11 @@ func UpdatePathAttrs(global *config.Global, peer *config.Neighbor, info *PeerInf
 		path.RemovePrivateAS(peer.Config.LocalAs, peer.State.RemovePrivateAs)
 
 		// AS_PATH handling
-		path.PrependAsn(peer.Config.LocalAs, 1)
+		confed := peer.IsConfederationMember(global)
+		path.PrependAsn(peer.Config.LocalAs, 1, confed)
+		if !confed {
+			path.removeConfedAs()
+		}
 
 		// MED Handling
 		if med := path.getPathAttr(bgp.BGP_ATTR_TYPE_MULTI_EXIT_DISC); med != nil && !path.IsLocal() {
@@ -288,7 +292,7 @@ func UpdatePathAttrs(global *config.Global, peer *config.Neighbor, info *PeerInf
 		// if the path has AS_PATH path attribute, don't modify it.
 		// if not, attach *empty* AS_PATH path attribute.
 		if nh := path.getPathAttr(bgp.BGP_ATTR_TYPE_AS_PATH); nh == nil {
-			path.PrependAsn(0, 0)
+			path.PrependAsn(0, 0, false)
 		}
 
 		// For iBGP peers we are required to send local-pref attribute
@@ -711,6 +715,8 @@ func (path *Path) getAsListofSpecificType(getAsSeq, getAsSet bool) []uint32 {
 
 // PrependAsn prepends AS number.
 // This function updates the AS_PATH attribute as follows.
+// (If the peer is in the confederation member AS,
+//  replace AS_SEQUENCE in the following sentence with AS_CONFED_SEQUENCE.)
 //  1) if the first path segment of the AS_PATH is of type
 //     AS_SEQUENCE, the local system prepends the specified AS num as
 //     the last element of the sequence (put it in the left-most
@@ -729,7 +735,13 @@ func (path *Path) getAsListofSpecificType(getAsSeq, getAsSet bool) []uint32 {
 //  3) if the AS_PATH is empty, the local system creates a path
 //     segment of type AS_SEQUENCE, places the specified AS number
 //     into that segment, and places that segment into the AS_PATH.
-func (path *Path) PrependAsn(asn uint32, repeat uint8) {
+func (path *Path) PrependAsn(asn uint32, repeat uint8, confed bool) {
+	var segType uint8
+	if confed {
+		segType = bgp.BGP_ASPATH_ATTR_TYPE_CONFED_SEQ
+	} else {
+		segType = bgp.BGP_ASPATH_ATTR_TYPE_SEQ
+	}
 
 	original := path.GetAsPath()
 
@@ -747,7 +759,7 @@ func (path *Path) PrependAsn(asn uint32, repeat uint8) {
 
 	if len(asPath.Value) > 0 {
 		fst := asPath.Value[0].(*bgp.As4PathParam)
-		if fst.Type == bgp.BGP_ASPATH_ATTR_TYPE_SEQ {
+		if fst.Type == segType {
 			if len(fst.AS)+int(repeat) > 255 {
 				repeat = uint8(255 - len(fst.AS))
 			}
@@ -758,7 +770,7 @@ func (path *Path) PrependAsn(asn uint32, repeat uint8) {
 	}
 
 	if len(asns) > 0 {
-		p := bgp.NewAs4PathParam(bgp.BGP_ASPATH_ATTR_TYPE_SEQ, asns)
+		p := bgp.NewAs4PathParam(segType, asns)
 		asPath.Value = append([]bgp.AsPathParamInterface{p}, asPath.Value...)
 	}
 	path.setPathAttr(asPath)
@@ -797,6 +809,21 @@ func (path *Path) RemovePrivateAS(localAS uint32, option config.RemovePrivateAsO
 	return
 }
 
+func (path *Path) removeConfedAs() {
+	original := path.GetAsPath()
+	if original == nil {
+		return
+	}
+	newAsParams := make([]bgp.AsPathParamInterface, 0, len(original.Value))
+	for _, v := range original.Value {
+		p := v.(*bgp.As4PathParam)
+		if p.Type == bgp.BGP_ASPATH_ATTR_TYPE_SEQ || p.Type == bgp.BGP_ASPATH_ATTR_TYPE_SET {
+			newAsParams = append(newAsParams, p)
+		}
+	}
+	path.setPathAttr(bgp.NewPathAttributeAsPath(newAsParams))
+}
+
 func (path *Path) ReplaceAS(localAS, peerAS uint32) *Path {
 	original := path.GetAsPath()
 	if original == nil {
diff --git a/table/path_test.go b/table/path_test.go
index f2b77bc5..768b76bf 100644
--- a/table/path_test.go
+++ b/table/path_test.go
@@ -116,7 +116,7 @@ func TestPathPrependAsnToExistingSeqAttr(t *testing.T) {
 	peer := PathCreatePeer()
 	p := NewPath(peer[0], update.NLRI[0], false, update.PathAttributes, time.Now(), false)
 
-	p.PrependAsn(65000, 1)
+	p.PrependAsn(65000, 1, false)
 	assert.Equal([]uint32{65000, 65001, 65002, 65003, 65004, 65005, 0, 0, 0}, p.GetAsSeqList())
 }
 
@@ -138,7 +138,7 @@ func TestPathPrependAsnToNewAsPathAttr(t *testing.T) {
 	p := NewPath(peer[0], update.NLRI[0], false, update.PathAttributes, time.Now(), false)
 
 	asn := uint32(65000)
-	p.PrependAsn(asn, 1)
+	p.PrependAsn(asn, 1, false)
 	assert.Equal([]uint32{asn}, p.GetAsSeqList())
 }
 
@@ -166,7 +166,7 @@ func TestPathPrependAsnToNewAsPathSeq(t *testing.T) {
 	p := NewPath(peer[0], update.NLRI[0], false, update.PathAttributes, time.Now(), false)
 
 	asn := uint32(65000)
-	p.PrependAsn(asn, 1)
+	p.PrependAsn(asn, 1, false)
 	assert.Equal([]uint32{asn, 0, 0, 0}, p.GetAsSeqList())
 }
 
@@ -195,7 +195,7 @@ func TestPathPrependAsnToEmptyAsPathAttr(t *testing.T) {
 	p := NewPath(peer[0], update.NLRI[0], false, update.PathAttributes, time.Now(), false)
 
 	asn := uint32(65000)
-	p.PrependAsn(asn, 1)
+	p.PrependAsn(asn, 1, false)
 	assert.Equal([]uint32{asn, 0, 0, 0}, p.GetAsSeqList())
 }
 
@@ -233,7 +233,7 @@ func TestPathPrependAsnToFullPathAttr(t *testing.T) {
 	for _, v := range asns {
 		expected = append(expected, uint32(v))
 	}
-	p.PrependAsn(65000, 2)
+	p.PrependAsn(65000, 2, false)
 	assert.Equal(append(expected, []uint32{0, 0, 0}...), p.GetAsSeqList())
 }
 
diff --git a/table/policy.go b/table/policy.go
index 0d112bba..fe153cf4 100644
--- a/table/policy.go
+++ b/table/policy.go
@@ -2260,7 +2260,7 @@ func (a *AsPathPrependAction) Type() ActionType {
 	return ACTION_AS_PATH_PREPEND
 }
 
-func (a *AsPathPrependAction) Apply(path *Path, _ *PolicyOptions) *Path {
+func (a *AsPathPrependAction) Apply(path *Path, option *PolicyOptions) *Path {
 	var asn uint32
 	if a.useLeftMost {
 		aspath := path.GetAsSeqList()
@@ -2283,7 +2283,8 @@ func (a *AsPathPrependAction) Apply(path *Path, _ *PolicyOptions) *Path {
 		asn = a.asn
 	}
 
-	path.PrependAsn(asn, a.repeat)
+	confed := option != nil && option.Info.Confederation
+	path.PrependAsn(asn, a.repeat, confed)
 
 	return path
 }