From 7187e4302adbe163a7201fd72da6dfe7369ae3b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=99=88=E5=9B=BD=E4=BC=9F?= <366193849@qq.com>
Date: Tue, 14 Sep 2021 14:11:53 +0800
Subject: [PATCH] =?UTF-8?q?=E5=88=B7=E6=96=B0dns=E7=BC=93=E5=AD=98?=
MIME-Version: 1.0
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---
 FastGithub.Dns/DnsOverUdpServer.cs   | 17 ++------
 FastGithub.Dns/DnsPoisoningServer.cs | 13 +++++-
 FastGithub.Dns/SystemDnsUtil.cs      | 65 +---------------------------
 3 files changed, 17 insertions(+), 78 deletions(-)

diff --git a/FastGithub.Dns/DnsOverUdpServer.cs b/FastGithub.Dns/DnsOverUdpServer.cs
index d044004..517d1d4 100644
--- a/FastGithub.Dns/DnsOverUdpServer.cs
+++ b/FastGithub.Dns/DnsOverUdpServer.cs
@@ -1,7 +1,6 @@
 using DNS.Protocol;
 using FastGithub.Configuration;
 using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.Options;
 using System;
 using System.Net;
 using System.Net.Sockets;
@@ -29,13 +28,10 @@ namespace FastGithub.Dns
         /// <param name="logger"></param>
         public DnsOverUdpServer(
             RequestResolver requestResolver,
-            ILogger<DnsOverUdpServer> logger,
-            IOptionsMonitor<FastGithubOptions> options)
+            ILogger<DnsOverUdpServer> logger)
         {
             this.requestResolver = requestResolver;
-            this.logger = logger;
-
-            options.OnChange(opt => SystemDnsUtil.FlushResolverCache());
+            this.logger = logger; 
         }
 
         /// <summary>
@@ -63,8 +59,7 @@ namespace FastGithub.Dns
 
             try
             {
-                SystemDnsUtil.SetAsPrimitiveDns();
-                SystemDnsUtil.FlushResolverCache();
+                SystemDnsUtil.SetAsPrimitiveDns(); 
             }
             catch (Exception ex)
             {
@@ -140,11 +135,7 @@ namespace FastGithub.Dns
             catch (Exception ex)
             {
                 this.logger.LogWarning(ex.Message);
-            }
-            finally
-            {
-                SystemDnsUtil.FlushResolverCache();
-            }
+            } 
         }
     }
 }
diff --git a/FastGithub.Dns/DnsPoisoningServer.cs b/FastGithub.Dns/DnsPoisoningServer.cs
index b8c3494..c1403ce 100644
--- a/FastGithub.Dns/DnsPoisoningServer.cs
+++ b/FastGithub.Dns/DnsPoisoningServer.cs
@@ -6,6 +6,7 @@ using PacketDotNet;
 using System;
 using System.Linq;
 using System.Net;
+using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
 using System.Threading;
 using WinDivertSharp;
@@ -20,7 +21,14 @@ namespace FastGithub.Dns
         const string DNS_FILTER = "udp.DstPort == 53";
         private readonly FastGithubConfig fastGithubConfig;
         private readonly ILogger<DnsPoisoningServer> logger;
-        private readonly TimeSpan ttl = TimeSpan.FromSeconds(10d);
+        private readonly TimeSpan ttl = TimeSpan.FromSeconds(10d); 
+
+        /// <summary>
+        /// 刷新DNS缓存
+        /// </summary>
+        [SupportedOSPlatform("windows")]
+        [DllImport("dnsapi.dll", EntryPoint = "DnsFlushResolverCache", SetLastError = true)]
+        private static extern void DnsFlushResolverCache();  
 
         /// <summary>
         /// dns投毒后台服务
@@ -53,7 +61,7 @@ namespace FastGithub.Dns
             using var winDivertBuffer = new WinDivertBuffer(packetBuffer);
             var winDivertAddress = new WinDivertAddress();
 
-            SystemDnsUtil.FlushResolverCache();
+            DnsFlushResolverCache();
             while (cancellationToken.IsCancellationRequested == false)
             {
                 if (WinDivert.WinDivertRecv(handle, winDivertBuffer, ref winDivertAddress, ref packetLength))
@@ -73,6 +81,7 @@ namespace FastGithub.Dns
             }
 
             WinDivert.WinDivertClose(handle);
+            DnsFlushResolverCache();
         }
 
         /// <summary>
diff --git a/FastGithub.Dns/SystemDnsUtil.cs b/FastGithub.Dns/SystemDnsUtil.cs
index 9fec28b..69a3c14 100644
--- a/FastGithub.Dns/SystemDnsUtil.cs
+++ b/FastGithub.Dns/SystemDnsUtil.cs
@@ -1,12 +1,8 @@
 using FastGithub.Configuration;
 using System;
-using System.Collections.Generic;
-using System.Diagnostics;
 using System.Linq;
 using System.Net;
 using System.Net.NetworkInformation;
-using System.Runtime.InteropServices;
-using System.Runtime.Versioning;
 
 namespace FastGithub.Dns
 {
@@ -15,24 +11,6 @@ namespace FastGithub.Dns
     /// </summary> 
     static class SystemDnsUtil
     {
-        /// <summary>
-        /// 刷新DNS缓存
-        /// </summary>
-        [SupportedOSPlatform("windows")]
-        [DllImport("dnsapi.dll", EntryPoint = "DnsFlushResolverCache", SetLastError = true)]
-        private static extern void DnsFlushResolverCache();
-
-        /// <summary>
-        /// 刷新DNS缓存
-        /// </summary>
-        public static void FlushResolverCache()
-        {
-            if (OperatingSystem.IsWindows())
-            {
-                DnsFlushResolverCache();
-            }
-        }
-
         /// <summary>
         /// 设置为主dns
         /// </summary> 
@@ -50,12 +28,7 @@ namespace FastGithub.Dns
             if (firstRecord == null || LocalMachine.ContainsIPAddress(firstRecord) == false)
             {
                 var primitive = IPAddress.Loopback;
-                var nameServers = dnsAddresses.Prepend(primitive);
-                if (OperatingSystem.IsWindows())
-                {
-                    SetNameServers(@interface, nameServers);
-                }
-                else if (OperatingSystem.IsLinux())
+                if (OperatingSystem.IsLinux())
                 {
                     throw new FastGithubException($"不支持自动设置本机DNS，请手工添加{primitive}做为/etc/resolv.conf的第一条记录");
                 }
@@ -82,12 +55,7 @@ namespace FastGithub.Dns
             var firstRecord = dnsAddresses.FirstOrDefault();
             if (firstRecord != null && LocalMachine.ContainsIPAddress(firstRecord))
             {
-                var nameServers = dnsAddresses.Skip(1);
-                if (OperatingSystem.IsWindows())
-                {
-                    SetNameServers(@interface, nameServers);
-                }
-                else if (OperatingSystem.IsLinux())
+                if (OperatingSystem.IsLinux())
                 {
                     throw new FastGithubException($"不支持自动移除本机主DNS，请手工移除/etc/resolv.conf的第一条记录");
                 }
@@ -117,34 +85,5 @@ namespace FastGithub.Dns
                 .Where(item => item.GetIPProperties().UnicastAddresses.Any(a => a.Address.Equals(address)))
                 .FirstOrDefault();
         }
-
-
-        /// <summary>
-        /// 设置网口的dns
-        /// </summary>
-        /// <param name="interface"></param>
-        /// <param name="nameServers"></param>
-        [SupportedOSPlatform("windows")]
-        private static void SetNameServers(NetworkInterface @interface, IEnumerable<IPAddress> nameServers)
-        {
-            Netsh($@"interface ipv4 delete dns ""{@interface.Name}"" all");
-            foreach (var address in nameServers)
-            {
-                Netsh($@"interface ipv4 add dns ""{@interface.Name}"" {address} validate=no");
-            }
-
-            static void Netsh(string arguments)
-            {
-                var netsh = new ProcessStartInfo
-                {
-                    FileName = "netsh.exe",
-                    Arguments = arguments,
-                    CreateNoWindow = true,
-                    UseShellExecute = false,
-                    WindowStyle = ProcessWindowStyle.Hidden
-                };
-                Process.Start(netsh)?.WaitForExit();
-            }
-        }
     }
 }
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