Initial version for the address server

address-server/main.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"net"
+	"fmt"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const (
+	// This is the default port for client and server; if running locally, change the game to use `hostPort=2301`
+	AddressServerPort = 2300
+	UdpBufferSize     = 1200
+)
+
+func main() {
+	log.WithField("port", AddressServerPort).Infoln("Starting address server")
+
+	udpAddress, err := net.ResolveUDPAddr("udp", fmt.Sprintf("%s:%d", "0.0.0.0", AddressServerPort))
+	if err != nil {
+		log.WithError(err).Panic("Failed to resolve udp address")
+	}
+
+	udpConn, err := net.ListenUDP("udp", udpAddress)
+	if err != nil {
+		log.WithError(err).Panic("Failed to listen for UDP packets.")
+	}
+
+	defer udpConn.Close()
+
+	udpBuffer := make([]byte, UdpBufferSize)
+
+	for {
+		bytes, udpClientAddress, err := udpConn.ReadFromUDP(udpBuffer)
+		if err != nil {
+			log.WithError(err).Warn("Failed to read UDP packet.")
+			continue
+		}
+
+		if bytes == 0 {
+			log.Warn("Failed to read any data from the UDP packet.")
+			continue
+		}
+
+		switch udpBuffer[0] {
+		case 9:
+			reply := make([]byte, 16)
+			reply[0] = 9 // reply with the same first byte
+			copy(reply[1:], []byte {0x02, 0x00, 0xd9, 0x49}) // these 4 are unknown, but it seems to work
+			copy(reply[5:], udpClientAddress.IP)
+			// from [9:12], all 0x00s
+			copy(reply[13:], udpBuffer[1:4])
+
+			log.WithField("reply", reply).WithField("ip", udpClientAddress.IP).Info("Replying to request.")
+			udpConn.WriteToUDP(reply, udpClientAddress)
+		case 10:
+			// TODO: reply back with the same message
+		}
+
+		log.WithField("fist_byte", udpBuffer[0]).WithField("ip", udpClientAddress.IP).Info("Got first byte")
+	}
+}