feat:新增server upd转发功能

cmd/udprelay/main.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"net"
+
+	"omnisocketgo/cmd/internal/server"
+)
+
+func main() {
+	listenAddr := flag.String("listen", ":9003", "UDP relay listen address (downstream, for KCP peer to connect)")
+	upstreamAddr := flag.String("upstream", "127.0.0.1:9002", "upstream KCP server address (server D)")
+	flag.Parse()
+
+	udpAddr, err := net.ResolveUDPAddr("udp", *listenAddr)
+	if err != nil {
+		log.Fatalf("resolve listen address %s: %v", *listenAddr, err)
+	}
+
+	conn, err := net.ListenUDP("udp", udpAddr)
+	if err != nil {
+		log.Fatalf("listen udp on %s: %v", *listenAddr, err)
+	}
+
+	relay, err := server.NewUDPRelay(conn, *upstreamAddr)
+	if err != nil {
+		_ = conn.Close()
+		log.Fatalf("create udp relay: %v", err)
+	}
+
+	log.Printf("udp relay listening on %s, upstream %s", conn.LocalAddr(), *upstreamAddr)
+
+	if err := relay.Serve(); err != nil {
+		log.Fatalf("udp relay serve: %v", err)
+	}
+}