bmp: Implement Information TLV on Initiation message

Currently, the TLV fields are implemented as BMPTLV on the Initiation
messages, but not enough decoded and required to be constructed in
binary format.

This patch introduces BMPInfoTLV and makes easy to handle the TLV
fields.

Note: This patch obsoletes BMPTLV structure.

Signed-off-by: IWASE Yusuke <[email protected]>

packet/bmp/bmp.go

@@ -519,58 +519,73 @@ const (
 	BMP_INIT_TLV_TYPE_SYS_NAME
 )
 
-const (
-	BMP_TERM_TLV_TYPE_STRING = iota
-	BMP_TERM_TLV_TYPE_REASON
-)
-
-const (
-	BMP_ROUTE_MIRRORING_TLV_TYPE_BGP_MSG = iota
-	BMP_ROUTE_MIRRORING_TLV_TYPE_INFO
-)
-
-type BMPTLV struct {
-	Type   uint16
-	Length uint16
-	Value  []byte
+type BMPInfoTLVInterface interface {
+	ParseValue([]byte) error
+	Serialize() ([]byte, error)
 }
 
-func NewBMPTLV(t uint16, v []byte) *BMPTLV {
-	return &BMPTLV{
-		Type:   t,
-		Length: uint16(len(v)),
-		Value:  v,
+type BMPInfoTLV struct {
+	Type   uint16
+	Length uint16
+}
+
+type BMPInfoTLVString struct {
+	BMPInfoTLV
+	Value string
+}
+
+func NewBMPInfoTLVString(t uint16, v string) *BMPInfoTLVString {
+	return &BMPInfoTLVString{
+		BMPInfoTLV: BMPInfoTLV{Type: t},
+		Value:      v,
 	}
 }
 
-func (tlv *BMPTLV) DecodeFromBytes(data []byte) error {
-	//TODO: check data length
-	tlv.Type = binary.BigEndian.Uint16(data[0:2])
-	tlv.Length = binary.BigEndian.Uint16(data[2:4])
-	tlv.Value = data[4 : 4+tlv.Length]
+func (s *BMPInfoTLVString) ParseValue(data []byte) error {
+	s.Value = string(data[:s.Length])
 	return nil
 }
 
-func (tlv *BMPTLV) Serialize() ([]byte, error) {
-	if tlv.Length == 0 {
-		tlv.Length = uint16(len(tlv.Value))
-	}
-	buf := make([]byte, 4+tlv.Length)
-	binary.BigEndian.PutUint16(buf[0:2], tlv.Type)
-	binary.BigEndian.PutUint16(buf[2:4], tlv.Length)
-	copy(buf[4:], tlv.Value)
+func (s *BMPInfoTLVString) Serialize() ([]byte, error) {
+	s.Length = uint16(len([]byte(s.Value)))
+	buf := make([]byte, 4)
+	binary.BigEndian.PutUint16(buf[0:2], s.Type)
+	binary.BigEndian.PutUint16(buf[2:4], s.Length)
+	buf = append(buf, []byte(s.Value)...)
 	return buf, nil
 }
 
-func (tlv *BMPTLV) Len() int {
-	return 4 + int(tlv.Length)
+type BMPInfoTLVUnknown struct {
+	BMPInfoTLV
+	Value []byte
+}
+
+func NewBMPInfoTLVUnknown(t uint16, v []byte) *BMPInfoTLVUnknown {
+	return &BMPInfoTLVUnknown{
+		BMPInfoTLV: BMPInfoTLV{Type: t},
+		Value:      v,
+	}
+}
+
+func (s *BMPInfoTLVUnknown) ParseValue(data []byte) error {
+	s.Value = data[:s.Length]
+	return nil
+}
+
+func (s *BMPInfoTLVUnknown) Serialize() ([]byte, error) {
+	s.Length = uint16(len([]byte(s.Value)))
+	buf := make([]byte, 4)
+	binary.BigEndian.PutUint16(buf[0:2], s.Type)
+	binary.BigEndian.PutUint16(buf[2:4], s.Length)
+	buf = append(buf, s.Value...)
+	return buf, nil
 }
 
 type BMPInitiation struct {
-	Info []BMPTLV
+	Info []BMPInfoTLVInterface
 }
 
-func NewBMPInitiation(info []BMPTLV) *BMPMessage {
+func NewBMPInitiation(info []BMPInfoTLVInterface) *BMPMessage {
 	return &BMPMessage{
 		Header: BMPHeader{
 			Version: BMP_VERSION,
@@ -583,11 +598,27 @@ func NewBMPInitiation(info []BMPTLV) *BMPMessage {
 }
 
 func (body *BMPInitiation) ParseBody(msg *BMPMessage, data []byte) error {
-	for len(data) > 0 {
-		tlv := BMPTLV{}
-		tlv.DecodeFromBytes(data)
+	for len(data) >= 4 {
+		tl := BMPInfoTLV{
+			Type:   binary.BigEndian.Uint16(data[0:2]),
+			Length: binary.BigEndian.Uint16(data[2:4]),
+		}
+		data = data[4:]
+		if len(data) < int(tl.Length) {
+			return fmt.Errorf("value lengh is not enough: %d bytes (%d bytes expected)", len(data), tl.Length)
+		}
+		var tlv BMPInfoTLVInterface
+		switch tl.Type {
+		case BMP_INIT_TLV_TYPE_STRING, BMP_INIT_TLV_TYPE_SYS_DESCR, BMP_INIT_TLV_TYPE_SYS_NAME:
+			tlv = &BMPInfoTLVString{BMPInfoTLV: tl}
+		default:
+			tlv = &BMPInfoTLVUnknown{BMPInfoTLV: tl}
+		}
+		if err := tlv.ParseValue(data); err != nil {
+			return err
+		}
 		body.Info = append(body.Info, tlv)
-		data = data[tlv.Len():]
+		data = data[tl.Length:]
 	}
 	return nil
 }
@@ -604,6 +635,11 @@ func (body *BMPInitiation) Serialize() ([]byte, error) {
 	return buf, nil
 }
 
+const (
+	BMP_TERM_TLV_TYPE_STRING = iota
+	BMP_TERM_TLV_TYPE_REASON
+)
+
 const (
 	BMP_TERM_REASON_ADMIN = iota
 	BMP_TERM_REASON_UNSPEC
@@ -650,6 +686,11 @@ func (body *BMPTermination) Serialize() ([]byte, error) {
 	return buf, nil
 }
 
+const (
+	BMP_ROUTE_MIRRORING_TLV_TYPE_BGP_MSG = iota
+	BMP_ROUTE_MIRRORING_TLV_TYPE_INFO
+)
+
 const (
 	BMP_ROUTE_MIRRORING_INFO_ERR_PDU = iota
 	BMP_ROUTE_MIRRORING_INFO_MSG_LOST

packet/bmp/bmp_test.go

@@ -41,8 +41,10 @@ func verify(t *testing.T, m1 *BMPMessage) {
 
 func Test_Initiation(t *testing.T) {
 	verify(t, NewBMPInitiation(nil))
-	tlv := NewBMPTLV(1, []byte{0x3, 0xb, 0x0, 0x0, 0x0, 0xf, 0x42, 0x40})
-	m := NewBMPInitiation([]BMPTLV{*tlv})
+	m := NewBMPInitiation([]BMPInfoTLVInterface{
+		NewBMPInfoTLVString(BMP_INIT_TLV_TYPE_STRING, "free-form UTF-8 string"),
+		NewBMPInfoTLVUnknown(0xff, []byte{0x01, 0x02, 0x03, 0x04}),
+	})
 	verify(t, m)
 }
 

server/bmp.go

@@ -148,7 +148,7 @@ func (b *bmpClient) loop() {
 				return err
 			}
 
-			if err := write(bmp.NewBMPInitiation([]bmp.BMPTLV{})); err != nil {
+			if err := write(bmp.NewBMPInitiation([]bmp.BMPInfoTLVInterface{})); err != nil {
 				return false
 			}