added macOS 13 mtu API for FileHandleNetworkDeviceAttachment

network.go

@@ -4,6 +4,7 @@ package vz
 #cgo darwin CFLAGS: -x objective-c -fno-objc-arc
 #cgo darwin LDFLAGS: -lobjc -framework Foundation -framework Virtualization
 # include "virtualization.h"
+# include "virtualization_13.h"
 */
 import "C"
 import (
@@ -117,6 +118,8 @@ type FileHandleNetworkDeviceAttachment struct {
 	*pointer
 
 	*baseNetworkDeviceAttachment
+
+	mtu int
 }
 
 var _ NetworkDeviceAttachment = (*FileHandleNetworkDeviceAttachment)(nil)
@@ -138,13 +141,44 @@ func NewFileHandleNetworkDeviceAttachment(file *os.File) (*FileHandleNetworkDevi
 				C.int(file.Fd()),
 			),
 		),
+		mtu: 1500, // The default MTU is 1500.
 	}
 	runtime.SetFinalizer(attachment, func(self *FileHandleNetworkDeviceAttachment) {
 		objc.Release(self)
 	})
 	return attachment, nil
 }
 
+// SetMaximumTransmissionUnit sets the maximum transmission unit (MTU) associated with this attachment.
+//
+// The maximum MTU allowed is 65535, and the minimum MTU allowed is 1500. An invalid MTU value will result in an invalid
+// virtual machine configuration.
+//
+// The client side of the associated datagram socket must be properly configured with the appropriate values
+// for SO_SNDBUF, and SO_RCVBUF. Set these using the setsockopt(_:_:_:_:_:) system call. The system expects
+// the value of SO_RCVBUF to be at least double the value of SO_SNDBUF, and for optimal performance, the
+// recommended value of SO_RCVBUF is four times the value of SO_SNDBUF.
+//
+// This is only supported on macOS 13 and newer, ErrUnsupportedOSVersion will
+// be returned on older versions.
+func (f *FileHandleNetworkDeviceAttachment) SetMaximumTransmissionUnit(mtu int) error {
+	if macosMajorVersionLessThan(13) {
+		return ErrUnsupportedOSVersion
+	}
+	C.setMaximumTransmissionUnitVZFileHandleNetworkDeviceAttachment(
+		objc.Ptr(f),
+		C.NSInteger(mtu),
+	)
+	f.mtu = mtu
+	return nil
+}
+
+// MaximumTransmissionUnit returns the maximum transmission unit (MTU) associated with this attachment.
+// The default MTU is 1500.
+func (f *FileHandleNetworkDeviceAttachment) MaximumTransmissionUnit() int {
+	return f.mtu
+}
+
 // NetworkDeviceAttachment for a network device attachment.
 // see: https://developer.apple.com/documentation/virtualization/vznetworkdeviceattachment?language=objc
 type NetworkDeviceAttachment interface {

network_test.go

@@ -0,0 +1,47 @@
+package vz_test
+
+import (
+	"net"
+	"testing"
+
+	"github.com/Code-Hex/vz/v2"
+)
+
+func TestFileHandleNetworkDeviceAttachmentMTU(t *testing.T) {
+	if vz.MacosMajorVersionLessThan(13) {
+		t.Skip("FileHandleNetworkDeviceAttachment.SetMaximumTransmissionUnit is supported from macOS 13")
+	}
+
+	ln, err := net.ListenUDP("udp", &net.UDPAddr{
+		Port: 0,
+		IP:   net.ParseIP("127.0.0.1"),
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer ln.Close()
+
+	f, err := ln.File()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	attachment, err := vz.NewFileHandleNetworkDeviceAttachment(f)
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := attachment.MaximumTransmissionUnit()
+	if got != 1500 {
+		t.Fatalf("want default mtu 1500 but got %d", got)
+	}
+
+	want := 2000
+	if err := attachment.SetMaximumTransmissionUnit(want); err != nil {
+		t.Fatal(err)
+	}
+
+	got2 := attachment.MaximumTransmissionUnit()
+	if got2 != want {
+		t.Fatalf("want mtu %d but got %d", want, got)
+	}
+}

virtualization_13.h

@@ -43,4 +43,6 @@ const char *getSpiceAgentPortName();
 
 void startWithOptionsCompletionHandler(void *machine, void *queue, void *options, void *completionHandler);
 
-const char *getMacOSGuestAutomountTag();
+const char *getMacOSGuestAutomountTag();
+
+void setMaximumTransmissionUnitVZFileHandleNetworkDeviceAttachment(void *attachment, NSInteger mtu);

virtualization_13.m

@@ -452,4 +452,27 @@ void startWithOptionsCompletionHandler(void *machine, void *queue, void *options
     }
 #endif
     RAISE_UNSUPPORTED_MACOS_EXCEPTION();
+}
+
+/*!
+ @abstract The maximum transmission unit (MTU) associated with this attachment.
+ @discussion
+    The client side of the associated datagram socket must be properly configured with the appropriate values for
+    `SO_SNDBUF`, and `SO_RCVBUF`, which can be set using the `setsockopt` system call. The value of `SO_RCVBUF` is
+    expected to be at least double the value of `SO_SNDBUF`, and for optimal performance, the value of `SO_RCVBUF`
+    is recommended to be four times the value of `SO_SNDBUF`.
+
+    The default MTU is 1500.
+    The maximum MTU allowed is 65535, and the minimum MTU allowed is 1500. An invalid MTU value will result in an invalid
+    virtual machine configuration.
+ */
+void setMaximumTransmissionUnitVZFileHandleNetworkDeviceAttachment(void *attachment, NSInteger mtu)
+{
+#ifdef INCLUDE_TARGET_OSX_13
+    if (@available(macOS 13, *)) {
+        [(VZFileHandleNetworkDeviceAttachment *)attachment setMaximumTransmissionUnit:mtu];
+        return;
+    }
+#endif
+    RAISE_UNSUPPORTED_MACOS_EXCEPTION();
 }