extend attributes proto for Prefix SID support

Signed-off-by: Serguei Bezverkhi <sbezverk@cisco.com>

4 files changed, 283 insertions, 21 deletions

diff --git a/pkg/packet/bgp/bgp.go b/pkg/packet/bgp/bgp.go
index 84604312..f72a3706 100644
--- a/pkg/packet/bgp/bgp.go
+++ b/pkg/packet/bgp/bgp.go
@@ -31,7 +31,8 @@ import (
 )
 
 type MarshallingOption struct {
-	AddPath map[RouteFamily]BGPAddPathMode
+	AddPath    map[RouteFamily]BGPAddPathMode
+	Attributes map[BGPAttrType]bool
 }
 
 func IsAddPathEnabled(decode bool, f RouteFamily, options []*MarshallingOption) bool {
@@ -49,6 +50,18 @@ func IsAddPathEnabled(decode bool, f RouteFamily, options []*MarshallingOption)
 	}
 	return false
 }
+func IsAttributePresent(attr BGPAttrType, options []*MarshallingOption) bool {
+	for _, opt := range options {
+		if opt == nil {
+			continue
+		}
+		if o := opt.Attributes; o != nil {
+			_, ok := o[attr]
+			return ok
+		}
+	}
+	return false
+}
 
 const (
 	AFI_IP     = 1
@@ -1588,9 +1601,17 @@ type MPLSLabelStack struct {
 	Labels []uint32
 }
 
-func (l *MPLSLabelStack) DecodeFromBytes(data []byte) error {
+func (l *MPLSLabelStack) DecodeFromBytes(data []byte, options ...*MarshallingOption) error {
 	labels := []uint32{}
 	foundBottom := false
+	bottomExpected := true
+	if IsAttributePresent(BGP_ATTR_TYPE_PREFIX_SID, options) {
+		// If Update carries Prefix SID attribute then there is no a label stack,
+		// but just 3 bytes which are used to carry the lower portion of Prefix SID.
+		// There is no bottom stack indication in this case. Once 3 bytes are stored
+		// breaking out of the loop.
+		bottomExpected = false
+	}
 	for len(data) >= 3 {
 		label := uint32(data[0])<<16 | uint32(data[1])<<8 | uint32(data[2])
 		if label == WITHDRAW_LABEL || label == ZERO_LABEL {
@@ -1599,6 +1620,11 @@ func (l *MPLSLabelStack) DecodeFromBytes(data []byte) error {
 		}
 		data = data[3:]
 		labels = append(labels, label>>4)
+		if !bottomExpected {
+			// Faking found bottom.
+			foundBottom = true
+			break
+		}
 		if label&1 == 1 {
 			foundBottom = true
 			break
@@ -1613,7 +1639,7 @@ func (l *MPLSLabelStack) DecodeFromBytes(data []byte) error {
 	return nil
 }
 
-func (l *MPLSLabelStack) Serialize() ([]byte, error) {
+func (l *MPLSLabelStack) Serialize(options ...*MarshallingOption) ([]byte, error) {
 	buf := make([]byte, len(l.Labels)*3)
 	for i, label := range l.Labels {
 		if label == WITHDRAW_LABEL {
@@ -1624,6 +1650,13 @@ func (l *MPLSLabelStack) Serialize() ([]byte, error) {
 		buf[i*3+1] = byte((label >> 8) & 0xff)
 		buf[i*3+2] = byte(label & 0xff)
 	}
+	if IsAttributePresent(BGP_ATTR_TYPE_PREFIX_SID, options) {
+		// If Update carries Prefix SID attribute then there is no a label stack,
+		// but just 3 bytes which are used to carry the lower portion of Prefix SID.
+		// No need BoS bit set
+		return buf, nil
+	}
+
 	buf[len(buf)-1] |= 1
 	return buf, nil
 }
@@ -1721,7 +1754,7 @@ func (l *LabeledVPNIPAddrPrefix) DecodeFromBytes(data []byte, options ...*Marsha
 	}
 	l.Length = uint8(data[0])
 	data = data[1:]
-	l.Labels.DecodeFromBytes(data)
+	l.Labels.DecodeFromBytes(data, options...)
 	if int(l.Length)-8*(l.Labels.Len()) < 0 {
 		l.Labels.Labels = []uint32{}
 	}
@@ -1746,7 +1779,7 @@ func (l *LabeledVPNIPAddrPrefix) Serialize(options ...*MarshallingOption) ([]byt
 		}
 	}
 	buf = append(buf, l.Length)
-	lbuf, err := l.Labels.Serialize()
+	lbuf, err := l.Labels.Serialize(options...)
 	if err != nil {
 		return nil, err
 	}
@@ -8480,6 +8513,7 @@ var PathAttrFlags map[BGPAttrType]BGPAttrFlag = map[BGPAttrType]BGPAttrFlag{
 	BGP_ATTR_TYPE_AIGP:                     BGP_ATTR_FLAG_OPTIONAL,
 	BGP_ATTR_TYPE_LARGE_COMMUNITY:          BGP_ATTR_FLAG_TRANSITIVE | BGP_ATTR_FLAG_OPTIONAL,
 	BGP_ATTR_TYPE_LS:                       BGP_ATTR_FLAG_OPTIONAL,
+	BGP_ATTR_TYPE_PREFIX_SID:               BGP_ATTR_FLAG_TRANSITIVE | BGP_ATTR_FLAG_OPTIONAL,
 }
 
 // getPathAttrFlags returns BGP Path Attribute flags value from its type and
@@ -9515,6 +9549,7 @@ type PathAttributeMpReachNLRI struct {
 }
 
 func (p *PathAttributeMpReachNLRI) DecodeFromBytes(data []byte, options ...*MarshallingOption) error {
+
 	value, err := p.PathAttribute.DecodeFromBytes(data, options...)
 	if err != nil {
 		return err
@@ -12325,6 +12360,56 @@ func NewPathAttributeUnknown(flags BGPAttrFlag, typ BGPAttrType, value []byte) *
 	}
 }
 
+// BGPUpdateAttributes defines a map with a key as bgp attribute type
+// and value as bool. Value set to true indicates that the attribute specified by the key
+// exists in the bgp update.
+type BGPUpdateAttributes struct {
+	Attribute map[BGPAttrType]bool
+}
+
+func GetBGPUpdateAttributes(data []byte) map[BGPAttrType]bool {
+	m := make(map[BGPAttrType]bool)
+	for p := 0; p < len(data); {
+		flag := data[p]
+		p++
+		if p < len(data) {
+			t := data[p]
+			m[BGPAttrType(t)] = true
+		} else {
+			break
+		}
+		p++
+		var l uint16
+		// Checking for Extened
+		if flag&0x10 == 0x10 {
+			if p+2 <= len(data) {
+				l = binary.BigEndian.Uint16(data[p : p+2])
+			} else {
+				break
+			}
+			p += 2
+		} else {
+			if p < len(data) {
+				l = uint16(data[p])
+				p++
+			} else {
+				break
+			}
+		}
+		p += int(l)
+	}
+	return m
+}
+
+func GetBGPUpdateAttributesFromMsg(msg *BGPUpdate) map[BGPAttrType]bool {
+	m := make(map[BGPAttrType]bool)
+	for _, p := range msg.PathAttributes {
+		m[p.GetType()] = true
+	}
+
+	return m
+}
+
 func GetPathAttribute(data []byte) (PathAttributeInterface, error) {
 	if len(data) < 2 {
 		eCode := uint8(BGP_ERROR_UPDATE_MESSAGE_ERROR)
@@ -12440,6 +12525,11 @@ func (msg *BGPUpdate) DecodeFromBytes(data []byte, options ...*MarshallingOption
 	if len(data) < int(msg.TotalPathAttributeLen) {
 		return NewMessageError(eCode, eSubCode, nil, "path total attribute length exceeds message length")
 	}
+	attributes := GetBGPUpdateAttributes(data)
+	o := MarshallingOption{
+		Attributes: attributes,
+	}
+	options = append(options, &o)
 
 	msg.PathAttributes = []PathAttributeInterface{}
 	for pathlen := msg.TotalPathAttributeLen; pathlen > 0; {
@@ -12457,7 +12547,6 @@ func (msg *BGPUpdate) DecodeFromBytes(data []byte, options ...*MarshallingOption
 		if err != nil {
 			return err
 		}
-
 		err = p.DecodeFromBytes(data, options...)
 		if err != nil {
 			e = err.(*MessageError)
@@ -12519,6 +12608,11 @@ func (msg *BGPUpdate) Serialize(options ...*MarshallingOption) ([]byte, error) {
 	msg.WithdrawnRoutesLen = uint16(len(wbuf) - 2)
 	binary.BigEndian.PutUint16(wbuf, msg.WithdrawnRoutesLen)
 
+	attributes := GetBGPUpdateAttributesFromMsg(msg)
+	o := MarshallingOption{
+		Attributes: attributes,
+	}
+	options = append(options, &o)
 	pbuf := make([]byte, 2)
 	for _, p := range msg.PathAttributes {
 		onepbuf, err := p.Serialize(options...)
@@ -12538,6 +12632,7 @@ func (msg *BGPUpdate) Serialize(options ...*MarshallingOption) ([]byte, error) {
 		}
 		buf = append(buf, nbuf...)
 	}
+
 	return buf, nil
 }
 
diff --git a/pkg/packet/bgp/prefix_sid.go b/pkg/packet/bgp/prefix_sid.go
index 7dd90082..a7983bcd 100644
--- a/pkg/packet/bgp/prefix_sid.go
+++ b/pkg/packet/bgp/prefix_sid.go
@@ -5,6 +5,10 @@ import (
 	"encoding/binary"
 	"encoding/json"
 	"fmt"
+	"net"
+
+	"github.com/golang/protobuf/ptypes"
+	api "github.com/osrg/gobgp/api"
 )
 
 const (
@@ -14,9 +18,8 @@ const (
 type TLVType uint8
 
 type TLV struct {
-	Type     TLVType
-	Length   uint16
-	Reserved uint8
+	Type   TLVType
+	Length uint16
 }
 
 func (s *TLV) Len() int {
@@ -391,7 +394,7 @@ func (s *SRv6InformationSubTLV) MarshalJSON() ([]byte, error) {
 
 func (s *SRv6InformationSubTLV) String() string {
 	var buf bytes.Buffer
-	buf.WriteString(fmt.Sprintf("SID: %s ", string(s.SID)))
+	buf.WriteString(fmt.Sprintf("SID: %s ", net.IP(s.SID).To16().String()))
 	buf.WriteString(fmt.Sprintf("Flag: %d ", s.Flags))
 	buf.WriteString(fmt.Sprintf("Endpoint Behavior: %d ", s.EndpointBehavior))
 	for _, tlv := range s.SubSubTLVs {
@@ -540,3 +543,135 @@ func (s *SRv6SIDStructureSubSubTLV) String() string {
 		s.TranspositionOffset,
 	)
 }
+
+func NewPathAttributePrefixSID(psid *api.PrefixSID) (*PathAttributePrefixSID, error) {
+	t := BGP_ATTR_TYPE_PREFIX_SID
+	s := &PathAttributePrefixSID{
+		PathAttribute: PathAttribute{
+			Flags: PathAttrFlags[t],
+			Type:  t,
+		},
+		TLVs: make([]PrefixSIDTLVInterface, 0),
+	}
+	for _, raw := range psid.Tlvs {
+		var tlv ptypes.DynamicAny
+		if err := ptypes.UnmarshalAny(raw, &tlv); err != nil {
+			return nil, err
+		}
+		switch v := tlv.Message.(type) {
+		case *api.SRv6L3ServiceTLV:
+			tlvLength, tlvs, err := UnmarshalSubTLVs(v.SubTlvs)
+			if err != nil {
+				return nil, err
+			}
+			o := &SRv6L3ServiceAttribute{
+				TLV: TLV{
+					Type:   TLVType(5),
+					Length: tlvLength,
+				},
+			}
+			s.PathAttribute.Length += tlvLength
+			// Storing Sub TLVs in a Service TLV
+			o.SubTLVs = append(o.SubTLVs, tlvs...)
+			// Adding Service TLV to Path Attribute TLV slice.
+			s.TLVs = append(s.TLVs, o)
+		default:
+			return nil, fmt.Errorf("unknown or not implemented Prefix SID type: %+v", v)
+		}
+	}
+	// Final Path Attribute Length is 3 bytes of the header and 1 byte Reserved1
+	s.PathAttribute.Length += (3 + 1)
+	return s, nil
+}
+
+func UnmarshalSubTLVs(stlvs map[uint32]*api.SRv6TLV) (uint16, []PrefixSIDTLVInterface, error) {
+	p := make([]PrefixSIDTLVInterface, 0, len(stlvs))
+	l := uint16(0)
+	// v.SubTlvs is a map by sub tlv type and the value is a slice of sub tlvs of the specific type
+	for t, tlv := range stlvs {
+		switch t {
+		case 1:
+			// Sub TLV Type 1 is SRv6 Informational Sub TLV
+			for _, stlvRaw := range tlv.Tlv {
+				// Instantiating Information Sub TLV
+				info := &SRv6InformationSubTLV{
+					SubTLV: SubTLV{
+						Type: SubTLVType(1),
+					},
+					SubSubTLVs: make([]PrefixSIDTLVInterface, 0),
+				}
+				var raw ptypes.DynamicAny
+				if err := ptypes.UnmarshalAny(stlvRaw, &raw); err != nil {
+					return 0, nil, err
+				}
+				infoProto := raw.Message.(*api.SRv6InformationSubTLV)
+				info.SID = make([]byte, len(infoProto.Sid))
+				copy(info.SID, infoProto.Sid)
+				// TODO Once RFC is published add processing of flags
+				info.Flags = 0
+				info.EndpointBehavior = uint16(infoProto.EndpointBehavior)
+				var sstlvslength uint16
+				var sstlvs []PrefixSIDTLVInterface
+				if len(infoProto.SubSubTlvs) != 0 {
+					// Processing Sub Sub TLVs
+					var err error
+					sstlvslength, sstlvs, err = UnmarshalSubSubTLVs(infoProto.SubSubTlvs)
+					if err != nil {
+						return 0, nil, err
+					}
+					info.SubSubTLVs = append(info.SubSubTLVs, sstlvs...)
+				}
+				// SRv6 Information Sub TLV length consists 1 byte Resrved2, 16 bytes SID, 1 byte flags, 2 bytes Endpoint Behavior
+				// 1 byte Reserved3 and length of Sub Sub TLVs
+				info.SubTLV.Length = 1 + 16 + 1 + 2 + 1 + sstlvslength
+				// For total Srv6 Information Sub TLV length, adding 3 bytes of the Sub TLV header
+				l += info.SubTLV.Length + 4
+				p = append(p, info)
+			}
+		default:
+			return 0, nil, fmt.Errorf("unknown or not implemented Prefix SID Sub TLV type: %d", t)
+		}
+	}
+
+	return l, p, nil
+}
+
+func UnmarshalSubSubTLVs(stlvs map[uint32]*api.SRv6TLV) (uint16, []PrefixSIDTLVInterface, error) {
+	p := make([]PrefixSIDTLVInterface, 0)
+	l := uint16(0)
+	// v.SubTlvs is a map by sub tlv type and the value is a slice of sub tlvs of the specific type
+	for t, tlv := range stlvs {
+		switch t {
+		case 1:
+			// Sub Sub TLV Type 1 is SRv6 Structure Sub Sub TLV
+			for _, stlvRaw := range tlv.Tlv {
+				// Instantiating Information Sub TLV
+				structure := &SRv6SIDStructureSubSubTLV{
+					SubSubTLV: SubSubTLV{
+						Type:   SubSubTLVType(1),
+						Length: 6,
+					},
+				}
+				var raw ptypes.DynamicAny
+				if err := ptypes.UnmarshalAny(stlvRaw, &raw); err != nil {
+					return 0, nil, err
+				}
+				structureProto := raw.Message.(*api.SRv6StructureSubSubTLV)
+				structure.LocalBlockLength = uint8(structureProto.LocalBlockLength)
+				structure.LocatorNodeLength = uint8(structureProto.LocalNodeLength)
+				structure.FunctionLength = uint8(structureProto.FunctionLength)
+				structure.ArgumentLength = uint8(structureProto.ArgumentLength)
+				structure.TranspositionLength = uint8(structureProto.TranspositionLength)
+				structure.TranspositionOffset = uint8(structureProto.TranspositionOffset)
+
+				// SRv6 Structure Sub Sub TLV length consists of header 3 bytes, 6 bytes of value
+				l += (3 + 6)
+				p = append(p, structure)
+			}
+		default:
+			return 0, nil, fmt.Errorf("unknown or not implemented Prefix SID Sub TLV type: %d", t)
+		}
+	}
+
+	return l, p, nil
+}
diff --git a/pkg/packet/bgp/prefix_sid_test.go b/pkg/packet/bgp/prefix_sid_test.go
index 2df8a3a3..a286228c 100644
--- a/pkg/packet/bgp/prefix_sid_test.go
+++ b/pkg/packet/bgp/prefix_sid_test.go
@@ -3,6 +3,9 @@ package bgp
 import (
 	"bytes"
 	"testing"
+
+	"github.com/golang/protobuf/ptypes/any"
+	api "github.com/osrg/gobgp/api"
 )
 
 func TestRoundTripSubSubTLV(t *testing.T) {
@@ -88,3 +91,34 @@ func TestRoundTripPrefixSID(t *testing.T) {
 		})
 	}
 }
+
+func TestNewPathAttributePrefixSID(t *testing.T) {
+	tests := []struct {
+		name  string
+		input *api.PrefixSID
+	}{
+		{
+			name: "path attribute srv6 prefix sid",
+			input: &api.PrefixSID{
+				Tlvs: []*any.Any{
+					{
+						TypeUrl: "type.googleapis.com/gobgpapi.SRv6L3ServiceTLV",
+						Value:   []byte{10, 157, 1, 8, 1, 18, 152, 1, 10, 149, 1, 10, 50, 116, 121, 112, 101, 46, 103, 111, 111, 103, 108, 101, 97, 112, 105, 115, 46, 99, 111, 109, 47, 103, 111, 98, 103, 112, 97, 112, 105, 46, 83, 82, 118, 54, 73, 110, 102, 111, 114, 109, 97, 116, 105, 111, 110, 83, 117, 98, 84, 76, 86, 18, 95, 10, 16, 32, 1, 0, 0, 0, 5, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 18, 0, 24, 17, 34, 71, 8, 1, 18, 67, 10, 65, 10, 51, 116, 121, 112, 101, 46, 103, 111, 111, 103, 108, 101, 97, 112, 105, 115, 46, 99, 111, 109, 47, 103, 111, 98, 103, 112, 97, 112, 105, 46, 83, 82, 118, 54, 83, 116, 114, 117, 99, 116, 117, 114, 101, 83, 117, 98, 83, 117, 98, 84, 76, 86, 18, 10, 8, 40, 16, 24, 24, 16, 40, 16, 48, 64},
+					},
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			p, err := NewPathAttributePrefixSID(tt.input)
+			if err != nil {
+				t.Fatalf("failed with error: %+v", err)
+			}
+			t.Logf("resulting prefix sid: %s", p.String())
+			b, _ := p.Serialize()
+			t.Logf("serialized prefix sid: %s", string(b))
+
+		})
+	}
+}
diff --git a/pkg/server/fsm.go b/pkg/server/fsm.go
index b5bcd2d8..b274c210 100644
--- a/pkg/server/fsm.go
+++ b/pkg/server/fsm.go
@@ -757,19 +757,17 @@ func capabilitiesFromConfig(pConf *config.Neighbor) []bgp.ParameterCapabilityInt
 		}
 	}
 
-	// unnumbered BGP
-	if pConf.Config.NeighborInterface != "" {
-		tuples := []*bgp.CapExtendedNexthopTuple{}
-		families, _ := config.AfiSafis(pConf.AfiSafis).ToRfList()
-		for _, family := range families {
-			if family == bgp.RF_IPv6_UC {
-				continue
-			}
-			tuple := bgp.NewCapExtendedNexthopTuple(family, bgp.AFI_IP6)
-			tuples = append(tuples, tuple)
+	// Extended Nexthop Capability (Code 5)
+	tuples := []*bgp.CapExtendedNexthopTuple{}
+	families, _ := config.AfiSafis(pConf.AfiSafis).ToRfList()
+	for _, family := range families {
+		if family == bgp.RF_IPv6_UC {
+			continue
 		}
-		caps = append(caps, bgp.NewCapExtendedNexthop(tuples))
+		tuple := bgp.NewCapExtendedNexthopTuple(family, bgp.AFI_IP6)
+		tuples = append(tuples, tuple)
 	}
+	caps = append(caps, bgp.NewCapExtendedNexthop(tuples))
 
 	// ADD-PATH Capability
 	if c := capAddPathFromConfig(pConf); c != nil {