play around

go.mod

@@ -0,0 +1,3 @@
+module github.com/crip
+
+go 1.22.2

main.go

@@ -0,0 +1,54 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"net"
+
+	"github.com/crip/ripv2"
+)
+
+func main() {
+	rip := ripv2.New()
+	addr := net.UDPAddr{
+		Port: 520,
+		IP:   net.ParseIP("224.0.0.9"),
+	}
+	conn, err := net.ListenMulticastUDP("udp", nil, &addr)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	defer conn.Close()
+	buff := make([]byte, 1024)
+
+	/*
+		bytes, err := rip.Request(conn)
+		if err != nil {
+			log.Fatalln(err)
+		}
+
+		RipAddr := net.UDPAddr{
+			Port: 520,
+			IP:   net.ParseIP("224.0.0.9"),
+		}
+		bw, err := conn.WriteToUDP(bytes, &RipAddr)
+		if err != nil {
+			log.Fatalln(err)
+		}
+
+		log.Printf("wrote %d bytes\n", bw)
+
+	*/
+	n, err := conn.Read(buff)
+	if err != nil {
+		log.Fatalln(err)
+	}
+	if n == 0 {
+		log.Fatalln("empty")
+	}
+
+	if err := rip.Parse(&buff); err != nil {
+		log.Fatalln(err)
+	}
+	fmt.Println(rip)
+}

ripv2/constants.go

@@ -0,0 +1,7 @@
+package ripv2
+
+const (
+	ZERO = iota
+	REQUEST
+	RESPONSE
+)

ripv2/ripv2.go

@@ -0,0 +1,55 @@
+package ripv2
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"net"
+)
+
+type Message struct {
+	Command uint8
+	Version uint8
+	Zero    uint16
+	RIP     [25]RIP
+}
+
+type RIP struct {
+	AddrF   uint16
+	Zero    uint16
+	Addr    uint32
+	Packing uint64
+	Metric  uint32
+}
+
+func New() Message {
+	return Message{}
+}
+
+func (m *Message) Parse(b *[]byte) error {
+	if len(*b) == 0 {
+		return fmt.Errorf("can't parse empty data")
+	}
+
+	bytes := bytes.NewBuffer(*b)
+
+	if err := binary.Read(bytes, binary.LittleEndian, &m); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (m *Message) Request(conn *net.UDPConn) ([]byte, error) {
+	var buffer = make([]byte, 1024)
+	m.Command = REQUEST
+	m.Version = 2
+	buff := bytes.NewBuffer(buffer)
+	buff.Reset()
+	if err := binary.Write(buff, binary.LittleEndian, m); err != nil {
+		return []byte{}, err
+	}
+
+	fmt.Println(buff)
+	return buffer, nil
+}