Draft: big refactor

utils/udp.go

@@ -0,0 +1,77 @@
+package utils
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/vmihailenco/msgpack/v5"
+)
+
+type UDPPayload struct {
+	MagicNumber int    `msgpack:"magicNumber"`
+	Data        string `msgpack:"data"`
+}
+
+const (
+	BUFFER_SIZE  int = 1024
+	MAGIC_NUMBER int = 114514
+)
+
+func ListenUDP(
+	port string,
+	doneCh chan struct{},
+) (string, error) {
+	addr, err := net.ResolveUDPAddr("udp", ":"+port)
+	if err != nil {
+		return "", fmt.Errorf("failed to resolve address, %w", err)
+	}
+
+	conn, err := net.ListenUDP("udp", addr)
+	if err != nil {
+		return "", fmt.Errorf("failed to listen on addr '%v', %w", addr, err)
+	}
+	defer conn.Close()
+
+	dataCh := make(chan string)
+	go func() {
+		for {
+			buffer := make([]byte, BUFFER_SIZE)
+
+			n, _, err := conn.ReadFromUDP(buffer)
+			if err != nil {
+				continue
+			}
+
+			var payload UDPPayload
+			err = msgpack.Unmarshal(buffer[:n], &payload)
+			if err == nil && payload.MagicNumber == MAGIC_NUMBER {
+				dataCh <- payload.Data
+				return
+			}
+		}
+	}()
+
+	select {
+	case <-doneCh:
+		return "", nil
+	case data := <-dataCh:
+		return data, nil
+	}
+
+	return "", fmt.Errorf("failed to receive data")
+}
+
+func SendPayload(endpoint, data string) error {
+	conn, err := net.Dial("udp", endpoint)
+	if err != nil {
+		return fmt.Errorf("failed to dial endpoint")
+	}
+	defer conn.Close()
+
+	_, err = conn.Write([]byte(data))
+	if err != nil {
+		return fmt.Errorf("failed to send payload")
+	}
+
+	return nil
+}