Fix typos

Netch/Controllers/NFController.cs

@@ -37,7 +37,7 @@ public class NFController : IModeController
 
         Dial(NameList.AIO_FILTERLOOPBACK, _mode.FilterLoopback);
         Dial(NameList.AIO_FILTERINTRANET, _mode.FilterIntranet);
-        Dial(NameList.AIO_FILTERPARENT, _mode.FilterParent ?? _rdrConfig.HandleOnlyDNS);
+        Dial(NameList.AIO_FILTERPARENT, _mode.FilterParent ?? _rdrConfig.FilterParent);
         Dial(NameList.AIO_FILTERICMP, _mode.FilterICMP ?? _rdrConfig.FilterICMP);
         if (_mode.FilterICMP ?? _rdrConfig.FilterICMP)
             Dial(NameList.AIO_ICMPING, (_mode.FilterICMP != null ? _mode.ICMPDelay ?? 10 : _rdrConfig.ICMPDelay).ToString());

Netch/Controllers/PcapController.cs

@@ -26,7 +26,7 @@ public class PcapController : Guard, IModeController
 
     public override string Name => "pcap2socks";
 
-    public ModeFeature Features => 0;
+    public ModeFeature Features => ModeFeature.SupportSocks5Auth;
 
     public async Task StartAsync(Socks5Server server, Mode mode)
     {

Netch/Forms/SettingForm.cs

@@ -107,7 +107,7 @@ public partial class SettingForm : BindingForm
         BindCheckBox(UseCustomDNSCheckBox, b => { Global.Settings.TUNTAP.UseCustomDNS = b; }, Global.Settings.TUNTAP.UseCustomDNS);
 
         BindTextBox(TUNTAPDNSTextBox,
-            s => true,
+            s => UseCustomDNSCheckBox.Checked ? IPAddress.TryParse(s, out _) : true,
             s =>
             {
                 if (UseCustomDNSCheckBox.Checked)

Netch/Utils/DnsUtils.cs

@@ -1,11 +1,14 @@
 using System.Collections;
 using System.Net;
 using System.Net.Sockets;
+using Microsoft.VisualStudio.Threading;
 
 namespace Netch.Utils;
 
 public static class DnsUtils
 {
+    private static readonly AsyncSemaphore Lock = new(1);
+
     /// <summary>
     ///     缓存
     /// </summary>
@@ -14,6 +17,7 @@ public static class DnsUtils
 
     public static async Task<IPAddress?> LookupAsync(string hostname, AddressFamily inet = AddressFamily.Unspecified, int timeout = 3000)
     {
+        using var _ = await Lock.EnterAsync();
         try
         {
             var cacheResult = inet switch

Netch/Utils/Utils.cs

@@ -94,6 +94,9 @@ public static class Utils
 
     public static async Task<string> Sha256CheckSumAsync(string filePath)
     {
+        if (!File.Exists(filePath))
+            return "";
+
         try
         {
             await using var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read, 4096, true);