[client] Clean up match domain reg entries between config changes (#4676)

client/internal/winregistry/volatile_windows.go

@@ -0,0 +1,59 @@
+package winregistry
+
+import (
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/windows/registry"
+)
+
+var (
+	advapi          = syscall.NewLazyDLL("advapi32.dll")
+	regCreateKeyExW = advapi.NewProc("RegCreateKeyExW")
+)
+
+const (
+	// Registry key options
+	regOptionNonVolatile = 0x0 // Key is preserved when system is rebooted
+	regOptionVolatile    = 0x1 // Key is not preserved when system is rebooted
+
+	// Registry disposition values
+	regCreatedNewKey     = 0x1
+	regOpenedExistingKey = 0x2
+)
+
+// CreateVolatileKey creates a volatile registry key named path under open key root.
+// CreateVolatileKey returns the new key and a boolean flag that reports whether the key already existed.
+// The access parameter specifies the access rights for the key to be created.
+//
+// Volatile keys are stored in memory and are automatically deleted when the system is shut down.
+// This provides automatic cleanup without requiring manual registry maintenance.
+func CreateVolatileKey(root registry.Key, path string, access uint32) (registry.Key, bool, error) {
+	pathPtr, err := syscall.UTF16PtrFromString(path)
+	if err != nil {
+		return 0, false, err
+	}
+
+	var (
+		handle      syscall.Handle
+		disposition uint32
+	)
+
+	ret, _, _ := regCreateKeyExW.Call(
+		uintptr(root),
+		uintptr(unsafe.Pointer(pathPtr)),
+		0,                          // reserved
+		0,                          // class
+		uintptr(regOptionVolatile), // options - volatile key
+		uintptr(access),            // desired access
+		0,                          // security attributes
+		uintptr(unsafe.Pointer(&handle)),
+		uintptr(unsafe.Pointer(&disposition)),
+	)
+
+	if ret != 0 {
+		return 0, false, syscall.Errno(ret)
+	}
+
+	return registry.Key(handle), disposition == regOpenedExistingKey, nil
+}