//go:build windows

package dialer

import (
	"syscall"
	"testing"

	"golang.org/x/sys/windows"
)

// IP_MTU_DISCOVER on windows (ws2ipdef.h); control.DisableUDPFragment sets it to
// IP_PMTUDISC_DO, the same "don't fragment" state the linux helper checks.
const (
	windowsIPMTUDiscover = 71
	windowsPMTUDiscDo    = 1
)

// udpSocketDFSet reports whether the socket has "don't fragment" forced on.
// shater addition: upstream ships linux + darwin only, so the whole suite
// skipped on the dev host — where it is the one platform we can actually run it
// on before the router build.
func udpSocketDFSet(t *testing.T, sysConn syscall.Conn) bool {
	t.Helper()
	rawConn, err := sysConn.SyscallConn()
	if err != nil {
		t.Fatal(err)
	}
	var (
		value   int
		sockErr error
	)
	ctrlErr := rawConn.Control(func(fd uintptr) {
		value, sockErr = windows.GetsockoptInt(windows.Handle(fd), windows.IPPROTO_IP, windowsIPMTUDiscover)
	})
	if ctrlErr != nil {
		t.Fatal(ctrlErr)
	}
	if sockErr != nil {
		t.Skip("IP_MTU_DISCOVER is not readable on this host: ", sockErr)
	}
	return value == windowsPMTUDiscDo
}