refine FnHolder module

src/fn_holder.rs

@@ -1,4 +1,4 @@
-pub trait FnCast: Sized + Copy {}
+pub trait FnCast: Copy {}
 
 pub struct FnHolder<F: FnCast> {
     _lib: ::libloading::Library,
@@ -28,6 +28,7 @@ macro_rules! define_fn_dynamic_load {
         static $static_var: std::sync::OnceLock<Option<$crate::fn_holder::FnHolder<$fn_type>>> =
             std::sync::OnceLock::new();
 
+        #[allow(non_snake_case)]
         pub fn $load_fn() -> Option<$fn_type> {
             $static_var
                 .get_or_init(|| $crate::fn_holder::load_function($module_name, $fn_name))
@@ -41,12 +42,12 @@ macro_rules! define_fn_dynamic_load {
 // usage
 use windows_sys::Win32::Foundation::BOOL;
 define_fn_dynamic_load!(
-    ProcessPrngFn,
+    ProcessPrngDeclear,
     unsafe extern "system" fn(pbdata: *mut u8, cbdata: usize) -> BOOL,
     PROCESS_PRNG,
-    get_fn_process_prng,
+    ProcessPrng,
     "bcryptprimitives.dll",
     "ProcessPrng"
 );
-let func = get_fn_process_prng().ok_or("Failed to load function ProcessPrng")?;
+let func = ProcessPrng().ok_or("Failed to load function ProcessPrng")?;
 */

src/util.rs

@@ -46,10 +46,17 @@ pub fn get_wintun_bin_pattern_path() -> std::io::Result<std::path::PathBuf> {
 //
 // WINAPI VOID RtlGetNtVersionNumbers (DWORD *MajorVersion, DWORD *MinorVersion, DWORD *BuildNumber);
 //
-pub(crate) fn get_windows_version() -> Result<(u32, u32, u32), libloading::Error> {
-    let library = unsafe { ::libloading::Library::new("ntdll")? };
-    type TheFn = unsafe extern "system" fn(*mut u32, *mut u32, *mut u32);
-    let func: TheFn = unsafe { library.get(b"RtlGetNtVersionNumbers\0").map(|sym| *sym)? };
+crate::define_fn_dynamic_load!(
+    RtlGetNtVersionNumbersDeclear,
+    unsafe extern "system" fn(*mut u32, *mut u32, *mut u32),
+    RTL_GET_NT_VERSION_NUMBERS,
+    RtlGetNtVersionNumbers,
+    "ntdll",
+    "RtlGetNtVersionNumbers"
+);
+
+pub(crate) fn get_windows_version() -> Result<(u32, u32, u32), Error> {
+    let func = RtlGetNtVersionNumbers().ok_or("Failed to load function RtlGetNtVersionNumbers")?;
     let (mut major, mut minor, mut build) = (0, 0, 0);
     unsafe { func(&mut major, &mut minor, &mut build) };
     Ok((major, minor, build))
@@ -139,16 +146,16 @@ pub fn get_active_network_interface_gateways() -> std::io::Result<Vec<IpAddr>> {
 }
 
 crate::define_fn_dynamic_load!(
-    SetInterfaceDnsSettingsFn,
+    SetInterfaceDnsSettingsDeclear,
     unsafe extern "system" fn(GUID, *const DNS_INTERFACE_SETTINGS) -> WIN32_ERROR,
-    g_SetInterfaceDnsSettings,
-    get_set_interface_dns_settings_fn,
+    SET_INTERFACE_DNS_SETTINGS,
+    SetInterfaceDnsSettings,
     "iphlpapi.dll",
     "SetInterfaceDnsSettings"
 );
 
 pub(crate) fn set_interface_dns_servers(interface: GUID, dns: &[IpAddr]) -> crate::Result<()> {
-    let func = get_set_interface_dns_settings_fn().ok_or("Failed to load function SetInterfaceDnsSettings")?;
+    let func = SetInterfaceDnsSettings().ok_or("Failed to load function SetInterfaceDnsSettings")?;
 
     // format L"1.1.1.1,8.8.8.8", or L"1.1.1.1 8.8.8.8".
     let dns = dns.iter().map(|ip| ip.to_string()).collect::<Vec<_>>().join(",");