feat(core): support AUTO option and filter non-IP NDIS interfaces for BindInterface (#10519)

* feat(core): support AUTO detection and manual selection for BindInterface (#10519)

- Implements the 3-state design agreed in #10519:
  1. Empty: do not bind interface, preserve existing behavior.
  2. AUTO: automatically detect default active physical network interface and bind to it.
  3. Specific interface: prioritize user-selected network interface.
- Centralizes interface resolution in NetworkUtils.GetRealBindInterfaceName().
- Supports AUTO in CoreConfigContextBuilder, Singbox, and V2ray template services.
- Adds comprehensive unit tests covering AUTO detection, context validation, and config generation.

* refactor: optimize AUTO bindInterface resolution and add mock-based tests

- Resolve AUTO interface once in CoreConfigContextBuilder and store in CoreConfigContext.ResolvedBindInterface as single-source-of-truth
- Downstream sing-box and Xray outbound/TUN services consume ResolvedBindInterface directly
- Unify TrimEx and case-insensitive check via NetworkUtils.IsAuto to tolerate user input whitespace
- Log and issue validator warning when AUTO fails to resolve any physical adapter
- Extract pure SelectDefaultInterface function with NetworkInterfaceCandidate for deterministic, mock-based unit testing
- Add comprehensive unit tests covering Ethernet vs Wi-Fi preference, no-gateway fallback, and virtual adapter filtering

* refactor(network): filter non-IP NDIS interfaces and simplify AUTO bindInterface resolution

* fix(ui,network): align BindInterface ComboBox width and refine physical NIC matching

* Update CoreConfigContextBuilder.cs

---------

Co-authored-by: 2dust <31833384+2dust@users.noreply.github.com>

v2rayN/ServiceLib/Common/NetworkUtils.cs

@@ -11,16 +11,19 @@ public static class NetworkUtils
         NetworkInterfaceType.FastEthernetT,
     ];
 
-    private static readonly string[] _allowedPhysicalNameKeywords =
+    private static readonly string[] _allowedPhysicalNamePrefixes =
     [
-        // Windows / Generic
-        "ethernet", "wlan", "wi-fi", "wifi",
-
         // Linux
         "eth", "enp", "ens", "eno", "enx", "wlp", "wlan",
 
         // macOS
-        "en0", "en1", "en2", "airport",
+        "en0", "en1", "en2",
+    ];
+
+    private static readonly string[] _allowedPhysicalNameKeywords =
+    [
+        // Windows / macOS / Generic
+        "ethernet", "wlan", "wi-fi", "wifi", "airport",
 
         // Chinese
         "以太网", "无线", "局域网"
@@ -31,14 +34,74 @@ public static class NetworkUtils
         // Generic
         "virtual", "loopback", "loop back",
 
-        // Common virtual adapters
+        // Common virtual / VPN / tunnel adapters
         "hyper-v", "vmware", "virtualbox", "vbox", "docker", "veth", "virbr", "cni",
         "flannel", "cali", "kube", "wintun", "wireguard", "zerotier", "tailscale", "utun",
+        "tap-windows", "tap adapter", "openvpn", "anyconnect", "vpn", "clash", "mihomo", "xray_tun",
+
+        // Windows NDIS filter sub-layers & pseudo-interfaces
+        "wan miniport", "lightweight filter", "filter driver", "packet scheduler", "npcap", "kernel debug",
 
         // Chinese
         "虚拟", "回环", "环回"
     ];
 
+    public static bool IsAutoBindInterface(string? bindInterface)
+    {
+        return string.Equals(bindInterface?.TrimEx(), Global.BindInterfaceAuto, StringComparison.OrdinalIgnoreCase);
+    }
+
+    public static List<string> GetBindInterfaceNames()
+    {
+        return GetLocalNetworkInterfaceNames().Prepend(Global.BindInterfaceAuto).AppendEmpty();
+    }
+
+    public static string? GetRealBindInterfaceName(string? bindInterface)
+    {
+        var trimmed = bindInterface?.TrimEx();
+        if (trimmed.IsNullOrEmpty())
+        {
+            return null;
+        }
+
+        return IsAutoBindInterface(trimmed) ? GetDefaultPhysicalInterfaceName() : trimmed;
+    }
+
+    /// <summary>
+    /// Resolves a default physical outbound interface using a heuristic (active IP-enabled physical NICs
+    /// with an IPv4 gateway, preferring Ethernet over Wi-Fi). This does not inspect OS routing metrics;
+    /// in multi-NIC environments with custom routing tables, specify the target interface name manually.
+    /// </summary>
+    public static string? GetDefaultPhysicalInterfaceName()
+    {
+        try
+        {
+            var upPhysicalNics = NetworkInterface.GetAllNetworkInterfaces()
+                .Where(IsAllowedPhysicalInterface)
+                .ToList();
+
+            if (upPhysicalNics.Count == 0)
+            {
+                return null;
+            }
+
+            var gatewayNics = upPhysicalNics.Where(HasIPv4Gateway).ToList();
+            var candidates = gatewayNics.Count > 0 ? gatewayNics : upPhysicalNics;
+
+            var bestNic = candidates.FirstOrDefault(ni =>
+                    ni.NetworkInterfaceType is NetworkInterfaceType.Ethernet or NetworkInterfaceType.GigabitEthernet)
+                ?? candidates.FirstOrDefault(ni => ni.NetworkInterfaceType == NetworkInterfaceType.Wireless80211)
+                ?? candidates.FirstOrDefault();
+
+            return bestNic?.Name;
+        }
+        catch (Exception ex)
+        {
+            Logging.SaveLog("GetDefaultPhysicalInterfaceName", ex);
+            return null;
+        }
+    }
+
     public static List<string> GetLocalNetworkInterfaceNames()
     {
         try
@@ -51,15 +114,16 @@ public static class NetworkUtils
                 .OrderBy(x => x)
                 .ToList();
         }
-        catch
+        catch (Exception ex)
         {
+            Logging.SaveLog("GetLocalNetworkInterfaceNames", ex);
             return [];
         }
     }
 
     private static bool IsAllowedPhysicalInterface(NetworkInterface ni)
     {
-        if (ni.OperationalStatus != OperationalStatus.Up)
+        if (ni.OperationalStatus != OperationalStatus.Up || !SupportsIP(ni))
         {
             return false;
         }
@@ -75,6 +139,38 @@ public static class NetworkUtils
             return true;
         }
 
+        if (_allowedPhysicalNamePrefixes.Any(prefix => ni.Name.StartsWith(prefix, StringComparison.OrdinalIgnoreCase)))
+        {
+            return true;
+        }
+
         return _allowedPhysicalNameKeywords.Any(keyword => interfaceText.Contains(keyword, StringComparison.OrdinalIgnoreCase));
     }
+
+    private static bool SupportsIP(NetworkInterface ni)
+    {
+        try
+        {
+            return ni.Supports(NetworkInterfaceComponent.IPv4) || ni.Supports(NetworkInterfaceComponent.IPv6);
+        }
+        catch
+        {
+            return false;
+        }
+    }
+
+    private static bool HasIPv4Gateway(NetworkInterface ni)
+    {
+        try
+        {
+            return ni.GetIPProperties().GatewayAddresses.Any(g =>
+                g.Address.AddressFamily == AddressFamily.InterNetwork
+                && !IPAddress.Any.Equals(g.Address)
+                && !IPAddress.None.Equals(g.Address));
+        }
+        catch
+        {
+            return false;
+        }
+    }
 }

v2rayN/ServiceLib/Global.cs

@@ -48,6 +48,7 @@ public class Global
     public const string MozillaRootProvider = "mozilla";
 
     public const string DefaultSecurity = "auto";
+    public const string BindInterfaceAuto = "AUTO";
     public const string DefaultNetwork = "raw";
     public const string RawHeaderHttp = "http";
     public const string None = "none";

v2rayN/ServiceLib/Handler/Builder/CoreConfigContextBuilder.cs

@@ -121,17 +121,28 @@ public class CoreConfigContextBuilder
             && !Utils.IsLocalIP(context.AppConfig.CoreBasicItem.SendThrough))
         {
             validatorResult.Warnings.Add(string.Format(ResUI.MsgInvalidProperty, ResUI.TbSettingsSendThrough));
-            var appConfig = JsonUtils.DeepCopy(config);
+            var appConfig = JsonUtils.DeepCopy(context.AppConfig);
             appConfig.CoreBasicItem.SendThrough = string.Empty;
             context = context with { AppConfig = appConfig };
         }
-        if (!context.AppConfig.CoreBasicItem.BindInterface.IsNullOrEmpty()
-            && (!Utils.ContainsInterfaceName(context.AppConfig.CoreBasicItem.BindInterface)
-            || !(context.IsTunEnabled || context.IsWindows)))
+        var bindInterface = context.AppConfig.CoreBasicItem.BindInterface?.TrimEx();
+        if (bindInterface.IsNotEmpty())
         {
-            validatorResult.Warnings.Add(string.Format(ResUI.MsgInvalidProperty, ResUI.TbSettingsBindInterface));
-            var appConfig = JsonUtils.DeepCopy(config);
-            appConfig.CoreBasicItem.BindInterface = string.Empty;
+            if (NetworkUtils.IsAutoBindInterface(bindInterface))
+            {
+                bindInterface = NetworkUtils.GetDefaultPhysicalInterfaceName()?.TrimEx();
+            }
+
+            if (bindInterface.IsNullOrEmpty()
+                || !Utils.ContainsInterfaceName(bindInterface)
+                || !(context.IsTunEnabled || context.IsWindows))
+            {
+                validatorResult.Warnings.Add(string.Format(ResUI.MsgInvalidProperty, ResUI.TbSettingsBindInterface));
+                bindInterface = string.Empty;
+            }
+
+            var appConfig = JsonUtils.DeepCopy(context.AppConfig);
+            appConfig.CoreBasicItem.BindInterface = bindInterface;
             context = context with { AppConfig = appConfig };
         }
 

v2rayN/ServiceLib/Services/CoreConfig/Singbox/SingboxConfigTemplateService.cs

@@ -145,7 +145,7 @@ public partial class CoreConfigSingboxService
 
     private void ApplyOutboundBindInterface()
     {
-        var bindInterface = _config.CoreBasicItem.BindInterface?.TrimEx();
+        var bindInterface = NetworkUtils.GetRealBindInterfaceName(_config.CoreBasicItem.BindInterface);
         if (bindInterface.IsNullOrEmpty())
         {
             return;

v2rayN/ServiceLib/Services/CoreConfig/V2ray/V2rayConfigTemplateService.cs

@@ -224,7 +224,7 @@ public partial class CoreConfigV2rayService
 
     private void ApplyOutboundBindInterface()
     {
-        var bindInterface = _config.CoreBasicItem.BindInterface?.TrimEx();
+        var bindInterface = NetworkUtils.GetRealBindInterfaceName(_config.CoreBasicItem.BindInterface);
         if (bindInterface.IsNullOrEmpty())
         {
             return;

v2rayN/ServiceLib/Services/CoreConfig/V2ray/V2rayInboundService.cs

@@ -79,7 +79,7 @@ public partial class CoreConfigV2rayService
                     tunInbound.settings.gateway.Add(address6);
                 }
 
-                var bindInterface = _config.CoreBasicItem.BindInterface?.TrimEx();
+                var bindInterface = NetworkUtils.GetRealBindInterfaceName(_config.CoreBasicItem.BindInterface);
                 if (!bindInterface.IsNullOrEmpty())
                 {
                     tunInbound.settings.autoOutboundsInterface = bindInterface;

v2rayN/v2rayN.Desktop/Views/OptionSettingWindow.axaml

@@ -444,7 +444,7 @@
                             x:Name="cmbbindInterface"
                             Grid.Row="22"
                             Grid.Column="1"
-                            Width="300"
+                            Width="200"
                             Margin="{StaticResource Margin4}"
                             IsEditable="True" />
                         <TextBlock

v2rayN/v2rayN.Desktop/Views/OptionSettingWindow.axaml.cs

@@ -60,7 +60,7 @@ public partial class OptionSettingWindow : WindowBase<OptionSettingViewModel>
         cmbRoutingRulesSourceUrl.ItemsSource = Global.RoutingRulesSources;
         cmbIPAPIUrl.ItemsSource = Global.IPAPIUrls;
         cmbRootCertificateProvider.ItemsSource = Global.RootCertProviders;
-        cmbbindInterface.ItemsSource = NetworkUtils.GetLocalNetworkInterfaceNames().AppendEmpty();
+        cmbbindInterface.ItemsSource = NetworkUtils.GetBindInterfaceNames();
 
         cmbMainGirdOrientation.ItemsSource = Utils.GetEnumNames<EGirdOrientation>();
 

v2rayN/v2rayN/Views/OptionSettingWindow.xaml.cs

@@ -56,7 +56,7 @@ public partial class OptionSettingWindow
         cmbRoutingRulesSourceUrl.ItemsSource = Global.RoutingRulesSources;
         cmbIPAPIUrl.ItemsSource = Global.IPAPIUrls;
         cmbRootCertificateProvider.ItemsSource = Global.RootCertProviders;
-        txtbindInterface.ItemsSource = NetworkUtils.GetLocalNetworkInterfaceNames().AppendEmpty();
+        txtbindInterface.ItemsSource = NetworkUtils.GetBindInterfaceNames();
 
         cmbMainGirdOrientation.ItemsSource = Utils.GetEnumNames<EGirdOrientation>();