From f45b880232a5e7a258af6cf2b827b4b7786d2864 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=99=88=E5=9B=BD=E4=BC=9F?= <366193849@qq.com>
Date: Thu, 24 Jun 2021 13:53:02 +0800
Subject: [PATCH] =?UTF-8?q?=E5=A2=9E=E5=8A=A0=E6=9C=AC=E6=9C=BA=E5=88=B7?=
 =?UTF-8?q?=E6=96=B0=E5=9F=9F=E5=90=8D=E7=9A=84dns=E5=8A=9F=E8=83=BD?=
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---
 FastGithub.Scanner/GithubDnsFlushService.cs | 47 +++++++++++++++++++++
 FastGithub.Scanner/GithubScanService.cs     |  5 ++-
 2 files changed, 51 insertions(+), 1 deletion(-)
 create mode 100644 FastGithub.Scanner/GithubDnsFlushService.cs

diff --git a/FastGithub.Scanner/GithubDnsFlushService.cs b/FastGithub.Scanner/GithubDnsFlushService.cs
new file mode 100644
index 0000000..45a8e28
--- /dev/null
+++ b/FastGithub.Scanner/GithubDnsFlushService.cs
@@ -0,0 +1,47 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+using System;
+using System.Runtime.InteropServices;
+using System.Runtime.Versioning;
+
+namespace FastGithub.Scanner
+{
+    [Service(ServiceLifetime.Singleton)]
+    sealed class GithubDnsFlushService
+    {
+        private readonly ILogger<GithubDnsFlushService> logger;
+        private readonly IOptionsMonitor<GithubLookupFactoryOptions> options;
+
+        [SupportedOSPlatform("windows")]
+        [DllImport("dnsapi.dll", EntryPoint = "DnsFlushResolverCacheEntry_A", CharSet = CharSet.Ansi)]
+        private static extern int DnsFlushResolverCacheEntry(string hostName);
+
+        public GithubDnsFlushService(
+            ILogger<GithubDnsFlushService> logger,
+            IOptionsMonitor<GithubLookupFactoryOptions> options)
+        {
+            this.logger = logger;
+            this.options = options;
+        }
+
+        public void FlushGithubResolverCache()
+        {
+            if (OperatingSystem.IsWindows())
+            {
+                try
+                {
+                    foreach (var domain in this.options.CurrentValue.Domains)
+                    {
+                        DnsFlushResolverCacheEntry(domain);
+                    }
+                    this.logger.LogInformation($"刷新本机相关域名的dns缓存成功");
+                }
+                catch (Exception ex)
+                {
+                    this.logger.LogWarning($"刷新本机相关域名的dns缓存失败：{ex.Message}");
+                }
+            }
+        }
+    }
+}
diff --git a/FastGithub.Scanner/GithubScanService.cs b/FastGithub.Scanner/GithubScanService.cs
index ec276f1..5efd383 100644
--- a/FastGithub.Scanner/GithubScanService.cs
+++ b/FastGithub.Scanner/GithubScanService.cs
@@ -17,6 +17,7 @@ namespace FastGithub.Scanner
     {
         private readonly GithubLookupFacotry lookupFactory;
         private readonly GithubScanResults scanResults;
+        private readonly GithubDnsFlushService dnsFlushService;
         private readonly ILoggerFactory loggerFactory;
         private readonly ILogger<GithubScanService> logger;
 
@@ -33,12 +34,14 @@ namespace FastGithub.Scanner
         public GithubScanService(
             GithubLookupFacotry lookupFactory,
             GithubScanResults scanResults,
+            GithubDnsFlushService dnsFlushService,
             IServiceProvider appService,
             ILoggerFactory loggerFactory,
             ILogger<GithubScanService> logger)
         {
             this.lookupFactory = lookupFactory;
             this.scanResults = scanResults;
+            this.dnsFlushService = dnsFlushService;
             this.loggerFactory = loggerFactory;
             this.logger = logger;
 
@@ -156,7 +159,7 @@ namespace FastGithub.Scanner
                     domainLogger.LogWarning(context.ToStatisticsString());
                 }
             }
-
+            this.dnsFlushService.FlushGithubResolverCache();
             this.logger.LogInformation($"结果扫描结束，共扫描{results.Length}条记录");
         }
     }