flows: implement ipv

engine/packet.go

@@ -8,11 +8,24 @@ type L3Info struct {
 	IHL      uint8
 	SrcIP    [4]byte
 	DstIP    [4]byte
+	SrcIPv6  [16]byte
+	DstIPv6  [16]byte
 	Length   uint16
 }
 
-func (i L3Info) SrcIPAddr() net.IP { return net.IP(i.SrcIP[:]) }
-func (i L3Info) DstIPAddr() net.IP { return net.IP(i.DstIP[:]) }
+func (i L3Info) SrcIPAddr() net.IP {
+	if i.Version == 6 {
+		return net.IP(i.SrcIPv6[:])
+	}
+	return net.IP(i.SrcIP[:])
+}
+
+func (i L3Info) DstIPAddr() net.IP {
+	if i.Version == 6 {
+		return net.IP(i.DstIPv6[:])
+	}
+	return net.IP(i.DstIP[:])
+}
 
 type TCPInfo struct {
 	SrcPort uint16
@@ -32,29 +45,105 @@ type UDPInfo struct {
 }
 
 func ParseL3(data []byte) (l3 L3Info, transport []byte, ok bool) {
-	if len(data) < 20 {
+	if len(data) < 1 {
 		return
 	}
 	version := data[0] >> 4
-	if version != 4 {
+	switch version {
+	case 4:
+		if len(data) < 20 {
+			return
+		}
+		ihl := data[0] & 0x0F
+		if ihl < 5 || len(data) < int(ihl)*4 {
+			return
+		}
+		totalLen := int(uint16(data[2])<<8 | uint16(data[3]))
+		if totalLen < int(ihl)*4 || totalLen > len(data) {
+			totalLen = len(data)
+		}
+		return L3Info{
+			Version:  4,
+			Protocol: data[9],
+			IHL:      ihl,
+			Length:   uint16(totalLen),
+			SrcIP:    [4]byte{data[12], data[13], data[14], data[15]},
+			DstIP:    [4]byte{data[16], data[17], data[18], data[19]},
+		}, data[ihl*4 : totalLen], true
+	case 6:
+		if len(data) < 40 {
+			return
+		}
+		payloadLen := int(uint16(data[4])<<8 | uint16(data[5]))
+		totalLen := 40 + payloadLen
+		if payloadLen == 0 || totalLen > len(data) {
+			totalLen = len(data)
+		}
+		protocol, tr, ipv6OK := parseIPv6Transport(data, data[6], totalLen)
+		if !ipv6OK {
+			return
+		}
+		var srcIP, dstIP [16]byte
+		copy(srcIP[:], data[8:24])
+		copy(dstIP[:], data[24:40])
+		return L3Info{
+			Version:  6,
+			Protocol: protocol,
+			SrcIPv6:  srcIP,
+			DstIPv6:  dstIP,
+			Length:   uint16(totalLen),
+		}, tr, true
+	default:
 		return
 	}
-	ihl := data[0] & 0x0F
-	if ihl < 5 || len(data) < int(ihl)*4 {
-		return
+}
+
+func parseIPv6Transport(data []byte, nextHeader uint8, totalLen int) (protocol uint8, transport []byte, ok bool) {
+	offset := 40
+	proto := nextHeader
+	for {
+		if offset > totalLen {
+			return 0, nil, false
+		}
+		switch proto {
+		case 0, 43, 60: // Hop-by-hop options, Routing, Destination options
+			if offset+2 > totalLen {
+				return 0, nil, false
+			}
+			hdrLen := (int(data[offset+1]) + 1) * 8
+			if hdrLen < 8 || offset+hdrLen > totalLen {
+				return 0, nil, false
+			}
+			proto = data[offset]
+			offset += hdrLen
+		case 44: // Fragment
+			if offset+8 > totalLen {
+				return 0, nil, false
+			}
+			// Only first fragment carries L4 headers.
+			fragOffset := (uint16(data[offset+2])<<8 | uint16(data[offset+3])) >> 3
+			if fragOffset != 0 {
+				return 0, nil, false
+			}
+			proto = data[offset]
+			offset += 8
+		case 51: // Authentication Header
+			if offset+2 > totalLen {
+				return 0, nil, false
+			}
+			hdrLen := (int(data[offset+1]) + 2) * 4
+			if hdrLen < 8 || offset+hdrLen > totalLen {
+				return 0, nil, false
+			}
+			proto = data[offset]
+			offset += hdrLen
+		default:
+			if offset > totalLen {
+				return 0, nil, false
+			}
+			return proto, data[offset:totalLen], true
+		}
 	}
-	totalLen := int(uint16(data[2])<<8 | uint16(data[3]))
-	if totalLen < int(ihl)*4 || totalLen > len(data) {
-		totalLen = len(data)
-	}
-	return L3Info{
-		Version:  4,
-		Protocol: data[9],
-		IHL:      ihl,
-		Length:   uint16(totalLen),
-		SrcIP:    [4]byte{data[12], data[13], data[14], data[15]},
-		DstIP:    [4]byte{data[16], data[17], data[18], data[19]},
-	}, data[ihl*4:totalLen], true
 }
 
 func ParseTCP(transport []byte) (TCPInfo, []byte, bool) {