use wg tun library; batching & locking improvements

overlay/tun_windows.go

@@ -6,7 +6,6 @@ package overlay
 import (
 	"crypto"
 	"fmt"
-	"io"
 	"net/netip"
 	"os"
 	"path/filepath"
@@ -241,10 +240,36 @@ func (t *winTun) SupportsMultiqueue() bool {
 	return false
 }
 
-func (t *winTun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
+func (t *winTun) NewMultiQueueReader() (BatchReadWriter, error) {
 	return nil, fmt.Errorf("TODO: multiqueue not implemented for windows")
 }
 
+// BatchRead reads a single packet (batch size 1 for Windows)
+func (t *winTun) BatchRead(bufs [][]byte, sizes []int) (int, error) {
+	n, err := t.Read(bufs[0])
+	if err != nil {
+		return 0, err
+	}
+	sizes[0] = n
+	return 1, nil
+}
+
+// WriteBatch writes packets individually (no batching for Windows)
+func (t *winTun) WriteBatch(bufs [][]byte, offset int) (int, error) {
+	for i, buf := range bufs {
+		_, err := t.Write(buf[offset:])
+		if err != nil {
+			return i, err
+		}
+	}
+	return len(bufs), nil
+}
+
+// BatchSize returns 1 for Windows (no batching)
+func (t *winTun) BatchSize() int {
+	return 1
+}
+
 func (t *winTun) Close() error {
 	// It seems that the Windows networking stack doesn't like it when we destroy interfaces that have active routes,
 	// so to be certain, just remove everything before destroying.