Use 'ConvertInterfaceLuidToIndex' to obtain the index

src/adapter.rs

@@ -22,11 +22,8 @@
     core::GUID,
     Win32::{
         Foundation::FALSE,
-        NetworkManagement::{
-            IpHelper::{ConvertLengthToIpv4Mask, IP_ADAPTER_ADDRESSES_LH},
-            Ndis::NET_LUID_LH,
-        },
-        System::{Com::CLSIDFromString, Threading::CreateEventA},
+        NetworkManagement::{IpHelper::ConvertLengthToIpv4Mask, Ndis::NET_LUID_LH},
+        System::Threading::CreateEventA,
     },
 };
 
@@ -35,29 +32,16 @@
     adapter: UnsafeHandle<wintun_raw::WINTUN_ADAPTER_HANDLE>,
     wintun: Wintun,
     guid: u128,
-}
-
-fn get_adapter_luid(wintun: &Wintun, adapter: wintun_raw::WINTUN_ADAPTER_HANDLE) -> NET_LUID_LH {
-    let mut luid: wintun_raw::NET_LUID = unsafe { std::mem::zeroed() };
-    unsafe { wintun.WintunGetAdapterLUID(adapter, &mut luid as *mut wintun_raw::NET_LUID) };
-    unsafe { std::mem::transmute(luid) }
+    index: u32,
+    luid: NET_LUID_LH,
 }
 
 impl Adapter {
     /// Returns the `Friendly Name` of this adapter,
     /// which is the human readable name shown in Windows
     pub fn get_name(&self) -> Result<String, Error> {
-        let name = util::guid_to_win_style_string(&GUID::from_u128(self.guid))?;
-        let mut friendly_name = None;
-
-        util::get_adapters_addresses(|address| {
-            let name_iter = unsafe { util::win_pstr_to_string(address.AdapterName) }?;
-            if name_iter == name {
-                friendly_name = Some(unsafe { util::win_pwstr_to_string(address.FriendlyName)? });
-            }
-            Ok(())
-        })?;
-        friendly_name.ok_or(format!("Unable to find matching {}", name).into())
+        let name = crate::ffi::luid_to_alias(&self.luid)?;
+        Ok(util::decode_utf16(&name))
     }
 
     /// Sets the `Friendly Name` of this adapter,
@@ -86,8 +70,6 @@
     /// Creates a new wintun adapter inside the name `name` with tunnel type `tunnel_type`
     ///
     /// Optionally a GUID can be specified that will become the GUID of this adapter once created.
-    /// Adapters obtained via this function will be able to return their adapter index via
-    /// [`Adapter::get_adapter_index`]
     pub fn create(wintun: &Wintun, name: &str, tunnel_type: &str, guid: Option<u128>) -> Result<Arc<Adapter>, Error> {
         let name_utf16: Vec<_> = name.encode_utf16().chain(std::iter::once(0)).collect();
         let tunnel_type_utf16: Vec<u16> = tunnel_type.encode_utf16().chain(std::iter::once(0)).collect();
@@ -111,22 +93,19 @@
         if result.is_null() {
             Err("Failed to create adapter".into())
         } else {
+            let luid = crate::ffi::alias_to_luid(&name_utf16)?;
+            let index = crate::ffi::luid_to_index(&luid)?;
             Ok(Arc::new(Adapter {
                 adapter: UnsafeHandle(result),
                 wintun: wintun.clone(),
                 guid,
+                index,
+                luid,
             }))
         }
     }
 
     /// Attempts to open an existing wintun interface name `name`.
-    ///
-    /// Adapters opened via this call will have an unknown GUID meaning [`Adapter::get_adapter_index`]
-    /// will always fail because knowing the adapter's GUID is required to determine its index.
-    /// Currently a workaround is to delete and re-create a new adapter every time one is needed so
-    /// that it gets created with a known GUID, allowing [`Adapter::get_adapter_index`] to works as
-    /// expected. There is likely a way to get the GUID of our adapter using the Windows Registry
-    /// or via the Win32 API, so PR's that solve this issue are always welcome!
     pub fn open(wintun: &Wintun, name: &str) -> Result<Arc<Adapter>, Error> {
         let name_utf16: Vec<u16> = OsStr::new(name).encode_wide().chain(std::iter::once(0)).collect();
 
@@ -137,24 +116,16 @@
         if result.is_null() {
             Err("WintunOpenAdapter failed".into())
         } else {
-            let mut guid = None;
-            util::get_adapters_addresses(|address: IP_ADAPTER_ADDRESSES_LH| {
-                let frindly_name = unsafe { util::win_pwstr_to_string(address.FriendlyName)? };
-                if frindly_name == name {
-                    let adapter_name = unsafe { util::win_pstr_to_string(address.AdapterName) }?;
-                    let adapter_name_utf16: Vec<u16> = adapter_name.encode_utf16().chain(std::iter::once(0)).collect();
-                    let adapter_name_ptr: *const u16 = adapter_name_utf16.as_ptr();
-                    let mut adapter: GUID = unsafe { std::mem::zeroed() };
-                    unsafe { CLSIDFromString(adapter_name_ptr, &mut adapter as *mut GUID) };
-                    guid = Some(adapter);
-                }
-                Ok(())
-            })?;
-            let guid = util::win_guid_to_u128(&guid.ok_or("Unable to find matching GUID")?);
+            let luid = crate::ffi::alias_to_luid(&name_utf16)?;
+            let index = crate::ffi::luid_to_index(&luid)?;
+            let guid = crate::ffi::luid_to_guid(&luid)?;
+            let guid = unsafe { std::mem::transmute(guid) };
             Ok(Arc::new(Adapter {
                 adapter: UnsafeHandle(result),
                 wintun: wintun.clone(),
                 guid,
+                index,
+                luid,
             }))
         }
     }
@@ -199,7 +170,7 @@
 
     /// Returns the Win32 LUID for this adapter
     pub fn get_luid(&self) -> NET_LUID_LH {
-        get_adapter_luid(&self.wintun, self.adapter.0)
+        self.luid
     }
 
     /// Set `MTU` of this adapter
@@ -217,18 +188,7 @@
     /// Returns the Win32 interface index of this adapter. Useful for specifying the interface
     /// when executing `netsh interface ip` commands
     pub fn get_adapter_index(&self) -> Result<u32, Error> {
-        let name = util::guid_to_win_style_string(&GUID::from_u128(self.guid))?;
-        let mut adapter_index = None;
-
-        util::get_adapters_addresses(|address| {
-            let name_iter = unsafe { util::win_pstr_to_string(address.AdapterName) }?;
-            if name_iter == name {
-                adapter_index = unsafe { Some(address.Anonymous1.Anonymous.IfIndex) };
-                // adapter_index = Some(address.Ipv6IfIndex);
-            }
-            Ok(())
-        })?;
-        adapter_index.ok_or(format!("Unable to find matching {}", name).into())
+        Ok(self.index)
     }
 
     /// Sets the IP address for this adapter, using command `netsh`.

src/ffi.rs

@@ -0,0 +1,43 @@
+use crate::wintun_raw::WCHAR;
+use std::{io, mem};
+use windows_sys::core::GUID;
+use windows_sys::Win32::NetworkManagement::IpHelper::{
+    ConvertInterfaceAliasToLuid, ConvertInterfaceLuidToAlias, ConvertInterfaceLuidToGuid, ConvertInterfaceLuidToIndex,
+};
+use windows_sys::Win32::NetworkManagement::Ndis::NET_LUID_LH;
+
+pub fn luid_to_alias(luid: &NET_LUID_LH) -> io::Result<Vec<WCHAR>> {
+    // IF_MAX_STRING_SIZE + 1
+    let mut alias = vec![0; 257];
+
+    match unsafe { ConvertInterfaceLuidToAlias(luid, alias.as_mut_ptr(), alias.len()) } {
+        0 => Ok(alias),
+        err => Err(io::Error::from_raw_os_error(err as _)),
+    }
+}
+
+pub fn alias_to_luid(alias: &[WCHAR]) -> io::Result<NET_LUID_LH> {
+    let mut luid = unsafe { mem::zeroed() };
+
+    match unsafe { ConvertInterfaceAliasToLuid(alias.as_ptr(), &mut luid) } {
+        0 => Ok(luid),
+        err => Err(io::Error::from_raw_os_error(err as _)),
+    }
+}
+pub fn luid_to_index(luid: &NET_LUID_LH) -> io::Result<u32> {
+    let mut index = 0;
+
+    match unsafe { ConvertInterfaceLuidToIndex(luid, &mut index) } {
+        0 => Ok(index),
+        err => Err(io::Error::from_raw_os_error(err as _)),
+    }
+}
+
+pub fn luid_to_guid(luid: &NET_LUID_LH) -> io::Result<GUID> {
+    let mut guid = unsafe { mem::zeroed() };
+
+    match unsafe { ConvertInterfaceLuidToGuid(luid, &mut guid) } {
+        0 => Ok(guid),
+        err => Err(io::Error::from_raw_os_error(err as _)),
+    }
+}

src/lib.rs

@@ -66,17 +66,18 @@
 //! # Features
 //!
 //! - `panic_on_unsent_packets`: Panics if a send packet is dropped without being sent. Useful for
 //! debugging packet issues because unsent packets that are dropped without being sent hold up
 //! wintun's internal ring buffer.
 //!
 //! # TODO:
 //! - Add async support
 //! Requires hooking into a windows specific reactor and registering read interest on wintun's read
 //! handle. Asyncify other slow operations via tokio::spawn_blocking. As always, PR's are welcome!
 //!
 
 mod adapter;
 mod error;
+mod ffi;
 mod log;
 mod packet;
 mod session;

src/util.rs

@@ -442,6 +442,11 @@ pub(crate) fn get_adapter_mtu(luid: &NET_LUID_LH) -> std::io::Result<usize> {
     }
 }
 
+pub fn decode_utf16(string: &[u16]) -> String {
+    let end = string.iter().position(|b| *b == 0).unwrap_or(string.len());
+    String::from_utf16_lossy(&string[..end])
+}
+
 #[repr(C, align(1))]
 #[derive(c2rust_bitfields::BitfieldStruct)]
 #[allow(non_snake_case)]