fix mux kcp connection

lib/mux/sysGetsock_windows.go

@@ -4,6 +4,7 @@ package mux
 
 import (
 	"errors"
+	"github.com/xtaci/kcp-go"
 	"net"
 	"os"
 )
@@ -11,6 +12,7 @@ import (
 func sysGetSock(fd *os.File) (bufferSize int, err error) {
 	// https://github.com/golang/sys/blob/master/windows/syscall_windows.go#L1184
 	// not support, WTF???
+	// Todo
 	// return syscall.GetsockoptInt((syscall.Handle)(unsafe.Pointer(fd.Fd())), syscall.SOL_SOCKET, syscall.SO_RCVBUF)
 	bufferSize = 10 * 1024 * 1024
 	return
@@ -30,6 +32,13 @@ func getConnFd(c net.Conn) (fd *os.File, err error) {
 		//	return
 		//}
 		return
+	case *kcp.UDPSession:
+		//fd, err = (*net.UDPConn)(unsafe.Pointer(c.(*kcp.UDPSession))).File()
+		//if err != nil {
+		//	return
+		//}
+		// Todo
+		return
 	default:
 		err = errors.New("mux:unknown conn type, only tcp or kcp")
 		return