Determine Wintun alias dynamically for WG tunnel

3 files changed, 35 insertions, 8 deletions

diff --git a/talpid-core/src/tunnel/wireguard/mod.rs b/talpid-core/src/tunnel/wireguard/mod.rs
index 5e9cd6704e..9fe6bec4e7 100644
--- a/talpid-core/src/tunnel/wireguard/mod.rs
+++ b/talpid-core/src/tunnel/wireguard/mod.rs
@@ -389,6 +389,11 @@ pub enum TunnelError {
     #[error(display = "Invalid tunnel interface name")]
     InterfaceNameError(#[error(source)] std::ffi::NulError),
 
+    /// Failed to convert adapter alias to UTF-8.
+    #[cfg(target_os = "windows")]
+    #[error(display = "Failed to convert adapter alias")]
+    InvalidAlias,
+
     /// Failed to set ip addresses on tunnel interface.
     #[cfg(target_os = "windows")]
     #[error(display = "Failed to set IP addresses on WireGuard interface")]
diff --git a/talpid-core/src/tunnel/wireguard/wireguard_go.rs b/talpid-core/src/tunnel/wireguard/wireguard_go.rs
index 58b77ab47a..2751fbdfbf 100644
--- a/talpid-core/src/tunnel/wireguard/wireguard_go.rs
+++ b/talpid-core/src/tunnel/wireguard/wireguard_go.rs
@@ -133,12 +133,15 @@ impl WgGoTunnel {
                 .iter()
                 .any(|config| config.allowed_ips.iter().any(|ip| ip.is_ipv6()));
 
+        let mut alias_ptr = std::ptr::null_mut();
+
         let handle = unsafe {
             wgTurnOn(
                 cstr_iface_name.as_ptr(),
                 config.mtu as i64,
                 wait_on_ipv6 as u8,
                 wg_config_str.as_ptr(),
+                &mut alias_ptr,
                 Some(logging_callback),
                 logging_context.0 as *mut libc::c_void,
             )
@@ -148,13 +151,25 @@ impl WgGoTunnel {
             return Err(TunnelError::FatalStartWireguardError);
         }
 
-        if !add_device_ip_addresses(&iface_name, &config.tunnel.addresses) {
+        let actual_iface_name = {
+            let actual_iface_name_c = unsafe { CStr::from_ptr(alias_ptr) };
+            let actual_iface_name = actual_iface_name_c
+                .to_str()
+                .map_err(|_| TunnelError::InvalidAlias)?
+                .to_string();
+            unsafe { wgFreePtr(alias_ptr as *mut c_void) };
+            actual_iface_name
+        };
+
+        log::debug!("Adapter alias: {}", actual_iface_name);
+
+        if !add_device_ip_addresses(&actual_iface_name, &config.tunnel.addresses) {
             // Todo: what kind of clean-up is required?
             return Err(TunnelError::SetIpAddressesError);
         }
 
         Ok(WgGoTunnel {
-            interface_name: iface_name.clone(),
+            interface_name: actual_iface_name,
             handle: Some(handle),
             _logging_context: logging_context,
         })
@@ -360,6 +375,7 @@ extern "C" {
         mtu: i64,
         wait_on_ipv6: u8,
         settings: *const i8,
+        iface_name_out: *const *mut std::os::raw::c_char,
         logging_callback: Option<LoggingCallback>,
         logging_context: *mut libc::c_void,
     ) -> i32;
diff --git a/wireguard/libwg/libwg_windows.go b/wireguard/libwg/libwg_windows.go
index 0718caeb6c..bc766418b1 100644
--- a/wireguard/libwg/libwg_windows.go
+++ b/wireguard/libwg/libwg_windows.go
@@ -6,8 +6,10 @@
 
 package main
 
+// #include <stdlib.h>
+import "C"
+
 import (
-	"C"
 	"bufio"
 	"fmt"
 	"strings"
@@ -64,8 +66,11 @@ func createInterfaceWatcherEvents(waitOnIpv6 bool, tunLuid uint64) []interfacewa
 }
 
 //export wgTurnOn
-func wgTurnOn(cIfaceName *C.char, mtu int, waitOnIpv6 bool, cSettings *C.char, logSink LogSink, logContext LogContext) int32 {
+func wgTurnOn(cIfaceName *C.char, mtu int, waitOnIpv6 bool, cSettings *C.char, cIfaceNameOut **C.char, logSink LogSink, logContext LogContext) int32 {
 	logger := logging.NewLogger(logSink, logContext)
+	if cIfaceNameOut != nil {
+		*cIfaceNameOut = nil
+	}
 
 	if cIfaceName == nil {
 		logger.Error.Println("cIfaceName is null")
@@ -109,13 +114,10 @@ func wgTurnOn(cIfaceName *C.char, mtu int, waitOnIpv6 bool, cSettings *C.char, l
 		logger.Error.Println("Failed to determine name of wintun adapter")
 		return ERROR_GENERAL_FAILURE
 	}
-
 	if actualInterfaceName != ifaceName {
 		// WireGuard picked a different name for the adapter than the one we expected.
 		// This indicates there is already an adapter with the name we intended to use.
-		nativeTun.Close()
-		logger.Error.Println("Failed to create adapter with specific name")
-		return ERROR_GENERAL_FAILURE
+		logger.Debug.Println("Failed to create adapter with specific name")
 	}
 
 	device := device.NewDevice(wintun, logger)
@@ -154,6 +156,10 @@ func wgTurnOn(cIfaceName *C.char, mtu int, waitOnIpv6 bool, cSettings *C.char, l
 		return ERROR_GENERAL_FAILURE
 	}
 
+	if cIfaceNameOut != nil {
+		*cIfaceNameOut = C.CString(actualInterfaceName)
+	}
+
 	return handle
 }