From e790ab513ae8894eccae4c52800ec9d5c052df75 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=99=88=E5=9B=BD=E4=BC=9F?= <366193849@qq.com>
Date: Mon, 29 Nov 2021 14:38:32 +0800
Subject: [PATCH] =?UTF-8?q?dns=E8=A7=A6=E5=8F=91tcp=20reset=E5=90=8E?=
 =?UTF-8?q?=E7=BC=93=E5=AD=9810=E5=88=86=E9=92=9F?=
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---
 Directory.Build.props                 |  2 +-
 FastGithub.DomainResolve/DnsClient.cs | 32 +++++++++++++++++++--------
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/Directory.Build.props b/Directory.Build.props
index d1c9920..3b895e7 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -1,6 +1,6 @@
 <Project>
 	<PropertyGroup>
-		<Version>2.1.1</Version>	
+		<Version>2.1.2</Version>	
 		<Nullable>enable</Nullable>
 		<TargetFramework>net6.0</TargetFramework>
 		<IsWebConfigTransformDisabled>true</IsWebConfigTransformDisabled> 		
diff --git a/FastGithub.DomainResolve/DnsClient.cs b/FastGithub.DomainResolve/DnsClient.cs
index 54911f1..cf928e3 100644
--- a/FastGithub.DomainResolve/DnsClient.cs
+++ b/FastGithub.DomainResolve/DnsClient.cs
@@ -9,7 +9,6 @@ using Microsoft.Extensions.Options;
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
-using System.IO;
 using System.Linq;
 using System.Net;
 using System.Net.Sockets;
@@ -34,7 +33,7 @@ namespace FastGithub.DomainResolve
         private readonly ConcurrentDictionary<string, SemaphoreSlim> semaphoreSlims = new();
         private readonly IMemoryCache dnsLookupCache = new MemoryCache(Options.Create(new MemoryCacheOptions()));
 
-        private readonly TimeSpan minTimeToLive = TimeSpan.FromMinutes(1d);
+        private readonly TimeSpan minTimeToLive = TimeSpan.FromSeconds(30d);
         private readonly TimeSpan maxTimeToLive = TimeSpan.FromMinutes(10d);
 
         private readonly int resolveTimeout = (int)TimeSpan.FromSeconds(4d).TotalMilliseconds;
@@ -123,7 +122,6 @@ namespace FastGithub.DomainResolve
                 {
                     return value;
                 }
-
                 var result = await this.LookupCoreAsync(dns, endPoint, fastSort, cancellationToken);
                 return this.dnsLookupCache.Set(key, result.Addresses, result.TimeToLive);
             }
@@ -131,15 +129,11 @@ namespace FastGithub.DomainResolve
             {
                 return Array.Empty<IPAddress>();
             }
-            catch (IOException ex) when (ex.InnerException is SocketException)
-            {
-                this.logger.LogWarning($"{endPoint.Host}@{dns}->{ex.Message}");
-                return this.dnsLookupCache.Set(key, Array.Empty<IPAddress>(), this.maxTimeToLive);
-            }
             catch (Exception ex)
             {
                 this.logger.LogWarning($"{endPoint.Host}@{dns}->{ex.Message}");
-                return Array.Empty<IPAddress>();
+                var expiration = IsTcpResetException(ex) ? this.maxTimeToLive : this.minTimeToLive;
+                return this.dnsLookupCache.Set(key, Array.Empty<IPAddress>(), expiration);
             }
             finally
             {
@@ -147,6 +141,26 @@ namespace FastGithub.DomainResolve
             }
         }
 
+        /// <summary>
+        /// 是否为因收到tcp reset导致的关闭
+        /// </summary>
+        /// <param name="ex"></param>
+        /// <returns></returns>
+        private static bool IsTcpResetException(Exception ex)
+        {
+            if (ex is SocketException socketException)
+            {
+                if (socketException.SocketErrorCode == SocketError.ConnectionReset)
+                {
+                    return true;
+                }
+            }
+
+            var inner = ex.InnerException;
+            return inner != null && IsTcpResetException(inner);
+        }
+
+
         /// <summary>
         /// 解析域名
         /// </summary>