[feature] Add multicast source IP detector util

Author: g3force

cmd/ssl-mc-sourcer/main.go

@@ -0,0 +1,56 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"net"
+	"time"
+)
+
+const maxDatagramSize = 8192
+
+var refereeAddress = flag.String("refereeAddress", "224.5.23.1:10003", "The multicast address of ssl-game-controller")
+var visionAddress = flag.String("visionAddress", "224.5.23.2:10006", "The multicast address of ssl-vision")
+
+var refereeRemotes []string
+
+func main() {
+	flag.Parse()
+
+	go watchAddress(*refereeAddress)
+	watchAddress(*visionAddress)
+}
+
+func watchAddress(address string) {
+	addr, err := net.ResolveUDPAddr("udp", address)
+	if err != nil {
+		log.Fatal(err)
+	}
+	conn, err := net.ListenMulticastUDP("udp", nil, addr)
+	if err != nil {
+		log.Fatal(err)
+	}
+	if err := conn.SetReadBuffer(maxDatagramSize); err != nil {
+		log.Printf("Could not set read buffer to %v.", maxDatagramSize)
+	}
+	log.Println("Receiving from", address)
+	for {
+		_, udpAddr, err := conn.ReadFromUDP([]byte{0})
+		if err != nil {
+			log.Print("Could not read", err)
+			time.Sleep(1 * time.Second)
+			continue
+		}
+		addRemote(address, udpAddr.IP.String())
+	}
+}
+
+func addRemote(address string, remote string) {
+	for _, a := range refereeRemotes {
+		if a == remote {
+			return
+		}
+	}
+	refereeRemotes = append(refereeRemotes, remote)
+	log.Printf("remote ip on %v: %v\n", address, remote)
+}