use wg tun library; batching & locking improvements

overlay/device.go

@@ -7,12 +7,26 @@ import (
 	"github.com/slackhq/nebula/routing"
 )
 
-type Device interface {
+// BatchReadWriter extends io.ReadWriteCloser with batch I/O operations
+type BatchReadWriter interface {
 	io.ReadWriteCloser
+
+	// BatchRead reads multiple packets at once
+	BatchRead(bufs [][]byte, sizes []int) (int, error)
+
+	// WriteBatch writes multiple packets at once
+	WriteBatch(bufs [][]byte, offset int) (int, error)
+
+	// BatchSize returns the optimal batch size for this device
+	BatchSize() int
+}
+
+type Device interface {
+	BatchReadWriter
 	Activate() error
 	Networks() []netip.Prefix
 	Name() string
 	RoutesFor(netip.Addr) routing.Gateways
 	SupportsMultiqueue() bool
-	NewMultiQueueReader() (io.ReadWriteCloser, error)
+	NewMultiQueueReader() (BatchReadWriter, error)
 }