decoders: fix sflow parsing of IP and MAC addresses (#261)

Due to IP and MAC addresses being a non-standard type, utils.BinaryRead
was not able to decode them. Move these two types inside utils.go and
teach BinaryRead to use them.

Co-authored-by: lspgn <lspgn@users.noreply.github.com>

Author: vincentbernat

decoders/sflow/datastructure.go

@@ -1,9 +1,6 @@
 package sflow
 
-import (
-	"fmt"
-	"net"
-)
+import "github.com/netsampler/goflow2/v2/decoders/utils"
 
 type SampledHeader struct {
 	Protocol       uint32 `json:"protocol"`
@@ -14,26 +11,20 @@ type SampledHeader struct {
 }
 
 type SampledEthernet struct {
-	Length  uint32     `json:"length"`
-	SrcMac  MacAddress `json:"src-mac"`
-	DstMac  MacAddress `json:"dst-mac"`
-	EthType uint32     `json:"eth-type"`
+	Length  uint32           `json:"length"`
+	SrcMac  utils.MacAddress `json:"src-mac"`
+	DstMac  utils.MacAddress `json:"dst-mac"`
+	EthType uint32           `json:"eth-type"`
 }
 
 type SampledIPBase struct {
-	Length   uint32    `json:"length"`
-	Protocol uint32    `json:"protocol"`
-	SrcIP    IPAddress `json:"src-ip"`
-	DstIP    IPAddress `json:"dst-ip"`
-	SrcPort  uint32    `json:"src-port"`
-	DstPort  uint32    `json:"dst-port"`
-	TcpFlags uint32    `json:"tcp-flags"`
-}
-
-type MacAddress []byte // purely for the formatting purpose
-
-func (s *MacAddress) MarshalJSON() ([]byte, error) {
-	return []byte(fmt.Sprintf("\"%s\"", net.HardwareAddr([]byte(*s)).String())), nil
+	Length   uint32          `json:"length"`
+	Protocol uint32          `json:"protocol"`
+	SrcIP    utils.IPAddress `json:"src-ip"`
+	DstIP    utils.IPAddress `json:"dst-ip"`
+	SrcPort  uint32          `json:"src-port"`
+	DstPort  uint32          `json:"dst-port"`
+	TcpFlags uint32          `json:"tcp-flags"`
 }
 
 type SampledIPv4 struct {
@@ -54,25 +45,25 @@ type ExtendedSwitch struct {
 }
 
 type ExtendedRouter struct {
-	NextHopIPVersion uint32    `json:"next-hop-ip-version"`
-	NextHop          IPAddress `json:"next-hop"`
-	SrcMaskLen       uint32    `json:"src-mask-len"`
-	DstMaskLen       uint32    `json:"dst-mask-len"`
+	NextHopIPVersion uint32          `json:"next-hop-ip-version"`
+	NextHop          utils.IPAddress `json:"next-hop"`
+	SrcMaskLen       uint32          `json:"src-mask-len"`
+	DstMaskLen       uint32          `json:"dst-mask-len"`
 }
 
 type ExtendedGateway struct {
-	NextHopIPVersion  uint32    `json:"next-hop-ip-version"`
-	NextHop           IPAddress `json:"next-hop"`
-	AS                uint32    `json:"as"`
-	SrcAS             uint32    `json:"src-as"`
-	SrcPeerAS         uint32    `json:"src-peer-as"`
-	ASDestinations    uint32    `json:"as-destinations"`
-	ASPathType        uint32    `json:"as-path-type"`
-	ASPathLength      uint32    `json:"as-path-length"`
-	ASPath            []uint32  `json:"as-path"`
-	CommunitiesLength uint32    `json:"communities-length"`
-	Communities       []uint32  `json:"communities"`
-	LocalPref         uint32    `json:"local-pref"`
+	NextHopIPVersion  uint32          `json:"next-hop-ip-version"`
+	NextHop           utils.IPAddress `json:"next-hop"`
+	AS                uint32          `json:"as"`
+	SrcAS             uint32          `json:"src-as"`
+	SrcPeerAS         uint32          `json:"src-peer-as"`
+	ASDestinations    uint32          `json:"as-destinations"`
+	ASPathType        uint32          `json:"as-path-type"`
+	ASPathLength      uint32          `json:"as-path-length"`
+	ASPath            []uint32        `json:"as-path"`
+	CommunitiesLength uint32          `json:"communities-length"`
+	Communities       []uint32        `json:"communities"`
+	LocalPref         uint32          `json:"local-pref"`
 }
 
 type IfCounters struct {

decoders/sflow/packet.go

@@ -1,26 +1,16 @@
 package sflow
 
-import (
-	"fmt"
-	"net/netip"
-)
+import "github.com/netsampler/goflow2/v2/decoders/utils"
 
 type Packet struct {
-	Version        uint32        `json:"version"`
-	IPVersion      uint32        `json:"ip-version"`
-	AgentIP        IPAddress     `json:"agent-ip"`
-	SubAgentId     uint32        `json:"sub-agent-id"`
-	SequenceNumber uint32        `json:"sequence-number"`
-	Uptime         uint32        `json:"uptime"`
-	SamplesCount   uint32        `json:"samples-count"`
-	Samples        []interface{} `json:"samples"`
-}
-
-type IPAddress []byte // purely for the formatting purpose
-
-func (s IPAddress) MarshalJSON() ([]byte, error) {
-	ip, _ := netip.AddrFromSlice([]byte(s))
-	return []byte(fmt.Sprintf("\"%s\"", ip.String())), nil
+	Version        uint32          `json:"version"`
+	IPVersion      uint32          `json:"ip-version"`
+	AgentIP        utils.IPAddress `json:"agent-ip"`
+	SubAgentId     uint32          `json:"sub-agent-id"`
+	SequenceNumber uint32          `json:"sequence-number"`
+	Uptime         uint32          `json:"uptime"`
+	SamplesCount   uint32          `json:"samples-count"`
+	Samples        []interface{}   `json:"samples"`
 }
 
 type SampleHeader struct {

decoders/utils/types.go

@@ -0,0 +1,20 @@
+package utils
+
+import (
+	"fmt"
+	"net"
+	"net/netip"
+)
+
+type MacAddress []byte // purely for the formatting purpose
+
+func (s *MacAddress) MarshalJSON() ([]byte, error) {
+	return []byte(fmt.Sprintf("\"%s\"", net.HardwareAddr([]byte(*s)).String())), nil
+}
+
+type IPAddress []byte // purely for the formatting purpose
+
+func (s IPAddress) MarshalJSON() ([]byte, error) {
+	ip, _ := netip.AddrFromSlice([]byte(s))
+	return []byte(fmt.Sprintf("\"%s\"", ip.String())), nil
+}

decoders/utils/utils.go

@@ -58,6 +58,10 @@ func BinaryRead(payload BytesBuffer, order binary.ByteOrder, data any) error {
 			}
 		case []uint8:
 			copy(data, bs)
+		case IPAddress:
+			copy(data, bs)
+		case MacAddress:
+			copy(data, bs)
 		case []int16:
 			for i := range data {
 				data[i] = int16(order.Uint16(bs[2*i:]))
@@ -105,6 +109,10 @@ func intDataSize(data any) int {
 		return len(data)
 	case []uint8:
 		return len(data)
+	case IPAddress:
+		return len(data)
+	case MacAddress:
+		return len(data)
 	case int16, uint16, *int16, *uint16:
 		return 2
 	case []int16: