Refactor OSPF checksumming

protocols/ospf/packetv3/fixtures/utils.go

 package fixtures
 
 import (
-	"net"
 	"os"
 	"testing"
 
+	"github.com/bio-routing/bio-rd/net"
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
 	"github.com/google/gopacket/pcapgo"
@@ -35,8 +35,14 @@ func Payload(raw []byte) (pl []byte, src, dst net.IP, err error) {
 	}
 
 	flowSrc, flowDst := packet.NetworkLayer().NetworkFlow().Endpoints()
-	src = net.IP(flowSrc.Raw())
-	dst = net.IP(flowDst.Raw())
+	src, err = net.IPFromBytes(flowSrc.Raw())
+	if err != nil {
+		return
+	}
+	dst, err = net.IPFromBytes(flowDst.Raw())
+	if err != nil {
+		return
+	}
 
 	pl = packet.NetworkLayer().LayerPayload()
 	return

protocols/ospf/packetv3/packet.go

@@ -4,8 +4,8 @@ import (
 	"bytes"
 	"encoding/binary"
 	"fmt"
-	gonet "net"
 
+	"github.com/bio-routing/bio-rd/net"
 	"github.com/bio-routing/bio-rd/util/checksum"
 	"github.com/bio-routing/bio-rd/util/decode"
 	"github.com/bio-routing/tflow2/convert"
@@ -42,7 +42,7 @@ const OSPFv3MessageHeaderLength = 16
 const OSPFv3MessagePacketLengthAtByte = 2
 const OSPFv3MessageChecksumAtByte = 12
 
-func (x *OSPFv3Message) Serialize(out *bytes.Buffer, src, dst gonet.IP) {
+func (x *OSPFv3Message) Serialize(out *bytes.Buffer, src, dst net.IP) {
 	buf := bytes.NewBuffer(nil)
 
 	buf.WriteByte(x.Version)
@@ -60,7 +60,7 @@ func (x *OSPFv3Message) Serialize(out *bytes.Buffer, src, dst gonet.IP) {
 	length := uint16(len(data))
 	putUint16(data, OSPFv3MessagePacketLengthAtByte, length)
 
-	checksum := checksum.IPv6UpperLayerChecksum(src, dst, OSPFProtocolNumber, data, OSPFv3MessageChecksumAtByte)
+	checksum := OSPFv3Checksum(data, src, dst)
 	putUint16(data, OSPFv3MessageChecksumAtByte, checksum)
 
 	out.Write(data)
@@ -70,7 +70,7 @@ func putUint16(b []byte, p int, v uint16) {
 	binary.BigEndian.PutUint16(b[p:p+2], v)
 }
 
-func DeserializeOSPFv3Message(buf *bytes.Buffer, src, dst gonet.IP) (*OSPFv3Message, int, error) {
+func DeserializeOSPFv3Message(buf *bytes.Buffer, src, dst net.IP) (*OSPFv3Message, int, error) {
 	pdu := &OSPFv3Message{}
 	data := buf.Bytes()
 
@@ -99,7 +99,7 @@ func DeserializeOSPFv3Message(buf *bytes.Buffer, src, dst gonet.IP) (*OSPFv3Mess
 		return nil, readBytes, fmt.Errorf("Invalid OSPF version: %d", pdu.Version)
 	}
 
-	expectedChecksum := checksum.IPv6UpperLayerChecksum(src, dst, OSPFProtocolNumber, data, OSPFv3MessageChecksumAtByte)
+	expectedChecksum := OSPFv3Checksum(data, src, dst)
 	if pdu.Checksum != expectedChecksum {
 		return nil, readBytes, fmt.Errorf("Checksum mismatch. Expected %#04x, got %#04x", expectedChecksum, pdu.Checksum)
 	}
@@ -113,6 +113,12 @@ func DeserializeOSPFv3Message(buf *bytes.Buffer, src, dst gonet.IP) (*OSPFv3Mess
 	return pdu, readBytes, nil
 }
 
+func OSPFv3Checksum(data []byte, src, dst net.IP) uint16 {
+	data[12] = 0
+	data[13] = 0
+	return checksum.IPv6UpperLayerChecksum(src, dst, OSPFProtocolNumber, data)
+}
+
 func (m *OSPFv3Message) ReadBody(buf *bytes.Buffer) (int, error) {
 	bodyLength := m.PacketLength - OSPFv3MessageHeaderLength
 	var body Serializable

util/checksum/ipv6_upperlayer.go

@@ -29,14 +29,14 @@ package checksum
 
 import (
 	"encoding/binary"
-	"net"
 
+	"github.com/bio-routing/bio-rd/net"
 	"github.com/bio-routing/tflow2/convert"
 	"golang.org/x/net/icmp"
 )
 
 func IPv6PseudoHeader(src, dst net.IP, lenght uint32, proto uint8) []byte {
-	header := icmp.IPv6PseudoHeader(src, dst)
+	header := icmp.IPv6PseudoHeader(src.ToNetIP(), dst.ToNetIP())
 
 	lenBytes := convert.Uint32Byte(uint32(lenght))
 	copy(header[32:36], lenBytes)
@@ -50,7 +50,7 @@ func IPv6PseudoHeader(src, dst net.IP, lenght uint32, proto uint8) []byte {
 //
 // Specify the position of the checksum using sumAt.
 // Use a value lower than 0 to not skip a checksum field.
-func IPv6UpperLayerChecksum(src, dst net.IP, proto uint8, pl []byte, sumAt int) uint16 {
+func IPv6UpperLayerChecksum(src, dst net.IP, proto uint8, pl []byte) uint16 {
 	header := IPv6PseudoHeader(src, dst, uint32(len(pl)), proto)
 	b := append(header, pl...)
 
@@ -59,9 +59,6 @@ func IPv6UpperLayerChecksum(src, dst net.IP, proto uint8, pl []byte, sumAt int)
 	// skipping only the checksum field itself."
 	var chk uint32
 	for i := 0; i < len(b); i += 2 {
-		if sumAt > 0 && i == len(header)+sumAt {
-			continue
-		}
 		chk += uint32(binary.BigEndian.Uint16(b[i : i+2]))
 	}