packet/bgp: Fix length calc when multiple RTM NLRIs

When multiple RTM NLRIs are composed in a single MP_REACH_NLRI, the current implementation will fail to decode those NLRIs because RouteTargetMembershipNLRI.DecodeFromBytes() tests the length of the given bytes even if including the subsequent bytes. This patch fixes to cut the bytes by using the prefix length before testing the byte length. Signed-off-by: IWASE Yusuke <[email protected]>
bganne · Jun 21, 2018 · 954562d · 954562d
1 parent e2752ae
commit 954562d
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Showing 2 changed files with 7 additions and 3 deletions.
diff --git a/packet/bgp/bgp.go b/packet/bgp/bgp.go
@@ -1955,7 +1955,7 @@ func (n *RouteTargetMembershipNLRI) DecodeFromBytes(data []byte, options ...*Mar
 		return NewMessageError(uint8(BGP_ERROR_UPDATE_MESSAGE_ERROR), uint8(BGP_ERROR_SUB_MALFORMED_ATTRIBUTE_LIST), nil, "prefix misses length field")
 	}
 	n.Length = data[0]
-	data = data[1:]
+	data = data[1 : n.Length/8+1]
 	if len(data) == 0 {
 		return nil
 	} else if len(data) != 12 {
@@ -1984,7 +1984,7 @@ func (n *RouteTargetMembershipNLRI) Serialize(options ...*MarshallingOption) ([]
 	}
 	offset := len(buf)
 	buf = append(buf, make([]byte, 5)...)
-	buf[offset] = 12 * 8
+	buf[offset] = 96
 	binary.BigEndian.PutUint32(buf[offset+1:], n.AS)
 	ebuf, err := n.RouteTarget.Serialize()
 	if err != nil {

diff --git a/packet/bgp/bgp_test.go b/packet/bgp/bgp_test.go
@@ -91,7 +91,7 @@ func Test_RouteTargetMembershipNLRIString(t *testing.T) {
 
 	// TwoOctetAsSpecificExtended
 	buf := make([]byte, 13)
-	buf[0] = 12
+	buf[0] = 96 // in bit length
 	binary.BigEndian.PutUint32(buf[1:5], 65546)
 	buf[5] = byte(EC_TYPE_TRANSITIVE_TWO_OCTET_AS_SPECIFIC) // typehigh
 	binary.BigEndian.PutUint16(buf[7:9], 65000)
@@ -108,6 +108,7 @@ func Test_RouteTargetMembershipNLRIString(t *testing.T) {
 
 	// IPv4AddressSpecificExtended
 	buf = make([]byte, 13)
+	buf[0] = 96 // in bit length
 	binary.BigEndian.PutUint32(buf[1:5], 65546)
 	buf[5] = byte(EC_TYPE_TRANSITIVE_IP4_SPECIFIC) // typehigh
 	ip := net.ParseIP("10.0.0.1").To4()
@@ -125,6 +126,7 @@ func Test_RouteTargetMembershipNLRIString(t *testing.T) {
 
 	// FourOctetAsSpecificExtended
 	buf = make([]byte, 13)
+	buf[0] = 96 // in bit length
 	binary.BigEndian.PutUint32(buf[1:5], 65546)
 	buf[5] = byte(EC_TYPE_TRANSITIVE_FOUR_OCTET_AS_SPECIFIC) // typehigh
 	buf[6] = byte(EC_SUBTYPE_ROUTE_TARGET)                   // subtype
@@ -142,6 +144,7 @@ func Test_RouteTargetMembershipNLRIString(t *testing.T) {
 
 	// OpaqueExtended
 	buf = make([]byte, 13)
+	buf[0] = 96 // in bit length
 	binary.BigEndian.PutUint32(buf[1:5], 65546)
 	buf[5] = byte(EC_TYPE_TRANSITIVE_OPAQUE) // typehigh
 	binary.BigEndian.PutUint32(buf[9:], 1000000)
@@ -157,6 +160,7 @@ func Test_RouteTargetMembershipNLRIString(t *testing.T) {
 
 	// Unknown
 	buf = make([]byte, 13)
+	buf[0] = 96 // in bit length
 	binary.BigEndian.PutUint32(buf[1:5], 65546)
 	buf[5] = 0x04 // typehigh
 	binary.BigEndian.PutUint32(buf[9:], 1000000)