From 2324634a860daad432a3cfd70ad4b6d26e9721aa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=80=81=E4=B9=9D?= <366193849@qq.com>
Date: Fri, 27 Aug 2021 21:35:00 +0800
Subject: [PATCH] =?UTF-8?q?=E7=B2=BE=E7=A1=AE=E5=88=A4=E6=96=AD=E4=B8=BBDN?=
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---
 FastGithub.Dns/DnsOverUdpHostedService.cs |  4 +--
 FastGithub.Dns/SystemDnsUtil.cs           | 40 +++++++++++++----------
 2 files changed, 24 insertions(+), 20 deletions(-)

diff --git a/FastGithub.Dns/DnsOverUdpHostedService.cs b/FastGithub.Dns/DnsOverUdpHostedService.cs
index 2edc2b2..e2747ee 100644
--- a/FastGithub.Dns/DnsOverUdpHostedService.cs
+++ b/FastGithub.Dns/DnsOverUdpHostedService.cs
@@ -57,7 +57,7 @@ namespace FastGithub.Dns
             {
                 try
                 {
-                    SystemDnsUtil.SetPrimitiveDns(IPAddress.Loopback);
+                    SystemDnsUtil.SetAsPrimitiveDns();
                     SystemDnsUtil.FlushResolverCache();
                 }
                 catch (Exception ex)
@@ -100,7 +100,7 @@ namespace FastGithub.Dns
 
             try
             {
-                SystemDnsUtil.RemovePrimitiveDns(IPAddress.Loopback);
+                SystemDnsUtil.RemoveFromPrimitiveDns();
             }
             catch (Exception ex)
             {
diff --git a/FastGithub.Dns/SystemDnsUtil.cs b/FastGithub.Dns/SystemDnsUtil.cs
index 4fba8e2..9fec28b 100644
--- a/FastGithub.Dns/SystemDnsUtil.cs
+++ b/FastGithub.Dns/SystemDnsUtil.cs
@@ -15,11 +15,6 @@ namespace FastGithub.Dns
     /// </summary> 
     static class SystemDnsUtil
     {
-        /// <summary>
-        /// www.baidu.com的ip
-        /// </summary>
-        private static readonly IPAddress www_baidu_com = IPAddress.Parse("183.232.231.172");
-
         /// <summary>
         /// 刷新DNS缓存
         /// </summary>
@@ -39,21 +34,22 @@ namespace FastGithub.Dns
         }
 
         /// <summary>
-        /// 设置主dns
-        /// </summary>
-        /// <param name="primitive"></param>
+        /// 设置为主dns
+        /// </summary> 
         /// <exception cref="FastGithubException"></exception> 
-        public static void SetPrimitiveDns(IPAddress primitive)
+        public static void SetAsPrimitiveDns()
         {
             var @interface = GetOutboundNetworkInterface();
             if (@interface == null)
             {
-                throw new FastGithubException($"找不到匹配的网络适配器来设置主DNS值：{primitive}");
+                throw new FastGithubException($"找不到匹配的网络适配器来设置主DNS");
             }
 
             var dnsAddresses = @interface.GetIPProperties().DnsAddresses;
-            if (primitive.Equals(dnsAddresses.FirstOrDefault()) == false)
+            var firstRecord = dnsAddresses.FirstOrDefault();
+            if (firstRecord == null || LocalMachine.ContainsIPAddress(firstRecord) == false)
             {
+                var primitive = IPAddress.Loopback;
                 var nameServers = dnsAddresses.Prepend(primitive);
                 if (OperatingSystem.IsWindows())
                 {
@@ -71,26 +67,34 @@ namespace FastGithub.Dns
         }
 
         /// <summary>
-        /// 移除主dns
-        /// </summary>
-        /// <param name="primitive"></param>
+        /// 从主dns移除
+        /// </summary> 
         /// <exception cref="FastGithubException"></exception> 
-        public static void RemovePrimitiveDns(IPAddress primitive)
+        public static void RemoveFromPrimitiveDns()
         {
             var @interface = GetOutboundNetworkInterface();
             if (@interface == null)
             {
-                throw new FastGithubException($"找不到匹配的网络适配器来移除主DNS值：{primitive}");
+                throw new FastGithubException($"找不到匹配的网络适配器来移除主DNS");
             }
 
             var dnsAddresses = @interface.GetIPProperties().DnsAddresses;
-            if (primitive.Equals(dnsAddresses.FirstOrDefault()))
+            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())
+                {
+                    throw new FastGithubException($"不支持自动移除本机主DNS，请手工移除/etc/resolv.conf的第一条记录");
+                }
+                else if (OperatingSystem.IsMacOS())
+                {
+                    throw new FastGithubException($"不支持自动移除本机主DNS，请手工移除连接网络的DNS的第一条记录");
+                }
             }
         }
 
@@ -101,7 +105,7 @@ namespace FastGithub.Dns
         /// <returns></returns> 
         private static NetworkInterface? GetOutboundNetworkInterface()
         {
-            var remoteEndPoint = new IPEndPoint(www_baidu_com, 443);
+            var remoteEndPoint = new IPEndPoint(IPAddress.Parse("1.1.1.1"), 53);
             var address = LocalMachine.GetLocalIPAddress(remoteEndPoint);
             if (address == null)
             {