使用客户端TTL；

可用率使用最近10次扫描结果来统计；

FastGithub.Dns/DnsOptions.cs

@@ -1,4 +1,5 @@
-using System.Net;
+using System;
+using System.Net;
 
 namespace FastGithub.Dns
 {
@@ -6,5 +7,7 @@ namespace FastGithub.Dns
     sealed class DnsOptions
     {
         public IPAddress UpStream { get; set; } = IPAddress.Parse("114.114.114.114");
+
+        public TimeSpan GithubTTL { get; set; } = TimeSpan.FromMinutes(10d);
     }
 }

FastGithub.Dns/DnsServiceCollectionExtensions.cs

@@ -18,8 +18,7 @@ namespace FastGithub
         public static IServiceCollection AddGithubDns(this IServiceCollection services, IConfiguration configuration)
         {
             var assembly = typeof(DnsServiceCollectionExtensions).Assembly;
-            return services         
+            return services          
-                .AddMemoryCache()
                 .AddServiceAndOptions(assembly, configuration)
                 .AddHostedService<DnsHostedService>()
                 .AddGithubScanner(configuration);

FastGithub.Dns/FastGithub.Dns.csproj

@@ -6,8 +6,7 @@
 	</PropertyGroup>
 
 	<ItemGroup>
-		<PackageReference Include="DNS" Version="6.1.0" />
+		<PackageReference Include="DNS" Version="6.1.0" /> 
-		<PackageReference Include="Microsoft.Extensions.Caching.Memory" Version="5.0.0" />
 	</ItemGroup>
 
 	<ItemGroup>

FastGithub.Dns/GithubRequestResolver.cs

@@ -2,12 +2,11 @@
 using DNS.Protocol;
 using DNS.Protocol.ResourceRecords;
 using FastGithub.Scanner;
-using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
 using System;
 using System.Linq;
-using System.Net;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -17,17 +16,16 @@ namespace FastGithub.Dns
     sealed class GithubRequestResolver : IRequestResolver
     {
         private readonly IGithubScanResults githubScanResults;
-        private readonly IMemoryCache memoryCache;
+        private readonly IOptionsMonitor<DnsOptions> options;
-        private readonly ILogger<GithubRequestResolver> logger;
+        private readonly ILogger<GithubRequestResolver> logger; 
-        private readonly TimeSpan TTL = TimeSpan.FromMinutes(10d);
 
         public GithubRequestResolver(
             IGithubScanResults githubScanResults,
-            IMemoryCache memoryCache,
+            IOptionsMonitor<DnsOptions> options,
             ILogger<GithubRequestResolver> logger)
         {
             this.githubScanResults = githubScanResults;
-            this.memoryCache = memoryCache;
+            this.options = options;
             this.logger = logger;
         }
 
@@ -39,11 +37,12 @@ namespace FastGithub.Dns
             if (question != null && question.Type == RecordType.A)
             {
                 var domain = question.Name.ToString();
-                var address = this.GetGithubAddress(domain, TTL);
+                var address = this.githubScanResults.FindBestAddress(domain);
 
                 if (address != null)
                 {
-                    var record = new IPAddressResourceRecord(question.Name, address);
+                    var ttl = this.options.CurrentValue.GithubTTL;
+                    var record = new IPAddressResourceRecord(question.Name, address, ttl);
                     response.AnswerRecords.Add(record);
                     this.logger.LogInformation(record.ToString());
                 }
@@ -51,37 +50,5 @@ namespace FastGithub.Dns
 
             return Task.FromResult<IResponse>(response);
         }
-
-        /// <summary>
-        /// 模拟TTL
-        /// 如果ip可用，则10分钟内返回缓存的ip，防止客户端ip频繁切换
-        /// </summary> 
-        /// <param name="domain"></param>
-        /// <param name="ttl"></param>
-        /// <returns></returns>
-        private IPAddress? GetGithubAddress(string domain, TimeSpan ttl)
-        {
-            if (domain.Contains("github", StringComparison.OrdinalIgnoreCase) == false)
-            {
-                return default;
-            }
-
-            var key = $"ttl:{domain}";
-            if (this.memoryCache.TryGetValue<IPAddress>(key, out var address))
-            {
-                if (this.githubScanResults.IsAvailable(domain, address))
-                {
-                    return address;
-                }
-                this.memoryCache.Remove(key);
-            }
-
-            address = this.githubScanResults.FindBestAddress(domain);
-            if (address != null)
-            {
-                this.memoryCache.Set(key, address, ttl);
-            }
-            return address;
-        }
     }
 }

FastGithub.Scanner/GithubContext.cs

@@ -8,7 +8,8 @@ namespace FastGithub.Scanner
         private record Github(
             string Domain,
             IPAddress Address,
-            double SuccessRate,
+            bool Available,
+            double AvailableRate,
             TimeSpan AvgElapsed);
 
         /// <summary>
@@ -58,8 +59,9 @@ namespace FastGithub.Scanner
             return new Github(
                 this.Domain,
                 this.Address,
-                this.History.GetSuccessRate(),
+                this.Available,
-                this.History.GetAvgElapsed()
+                this.History.AvailableRate,
+                this.History.AvgElapsed
                 ).ToString();
         }
     }

FastGithub.Scanner/GithubContextCollection.cs

@@ -54,9 +54,9 @@ namespace FastGithub.Scanner
             lock (this.syncRoot)
             {
                 return this.contextList
-                    .Where(item => item.Available && item.Domain == domain)
+                    .Where(item => item.Domain == domain && item.History.AvailableRate > 0d)
-                    .OrderByDescending(item => item.History.GetSuccessRate())
+                    .OrderByDescending(item => item.History.AvailableRate)
-                    .ThenBy(item => item.History.GetAvgElapsed())
+                    .ThenBy(item => item.History.AvgElapsed)
                     .Select(item => item.Address)
                     .FirstOrDefault();
             }

FastGithub.Scanner/GithubContextHistory.cs

@@ -1,74 +1,66 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 
 namespace FastGithub.Scanner
 {
     sealed class GithubContextHistory
     {
-        private record ScanLog(DateTime ScanTime, TimeSpan Elapsed);
+        private const int MAX_LOG_COUNT = 10;
+        private record ScanLog(bool Available, TimeSpan Elapsed);
 
-        private readonly Queue<ScanLog> successLogs = new();
+        private readonly Queue<ScanLog> scanLogs = new();
 
-        private readonly Queue<ScanLog> failureLogs = new();
+        /// <summary>
-
+        /// 获取可用率
-        private static readonly TimeSpan keepLogsTimeSpan = TimeSpan.FromHours(2d);
+        /// </summary>
-
+        /// <returns></returns>
-
+        public double AvailableRate
-        public void AddSuccess(TimeSpan elapsed)
         {
-            ClearStaleData(this.successLogs, keepLogsTimeSpan);
+            get
-            this.successLogs.Enqueue(new ScanLog(DateTime.Now, elapsed));
-        }
-
-        public void AddFailure()
-        {
-            ClearStaleData(this.failureLogs, keepLogsTimeSpan);
-            this.failureLogs.Enqueue(new ScanLog(DateTime.Now, TimeSpan.Zero));
-        }
-
-        static void ClearStaleData(Queue<ScanLog> logs, TimeSpan timeSpan)
-        {
-            var time = DateTime.Now.Subtract(timeSpan);
-            while (logs.TryPeek(out var log))
             {
-                if (log.ScanTime < time)
+                if (this.scanLogs.Count == 0)
                 {
-                    logs.TryDequeue(out _);
+                    return 0d;
                 }
-                break;
+
+                var availableCount = this.scanLogs.Count(item => item.Available);
+                return (double)availableCount / this.scanLogs.Count;
             }
         }
 
-        /// <summary>
-        /// 获取成功率
-        /// </summary>
-        /// <returns></returns>
-        public double GetSuccessRate()
-        {
-            var successCount = this.successLogs.Count;
-            var totalScanCount = successCount + this.failureLogs.Count;
-            return totalScanCount == 0 ? 0d : (double)successCount / totalScanCount;
-        }
 
         /// <summary>
         /// 获取平均耗时
         /// </summary>
         /// <returns></returns>
-        public TimeSpan GetAvgElapsed()
+        public TimeSpan AvgElapsed
         {
-            var totalScanCount = this.successLogs.Count + this.failureLogs.Count;
+            get
-            if (totalScanCount == 0)
             {
-                return TimeSpan.MaxValue;
+                var availableCount = 0;
-            }
+                var availableElapsed = TimeSpan.Zero;
 
-            var totalSuccessElapsed = TimeSpan.Zero;
+                foreach (var item in this.scanLogs)
-            foreach (var item in this.successLogs)
+                {
+                    if (item.Available == true)
+                    {
+                        availableCount += 1;
+                        availableElapsed = availableElapsed.Add(item.Elapsed);
+                    }
+                }
+
+                return availableCount == 0 ? TimeSpan.MaxValue : availableElapsed / availableCount;
+            }
+        }
+
+        public void Add(bool available, TimeSpan elapsed)
+        {
+            this.scanLogs.Enqueue(new ScanLog(available, elapsed));
+            while (this.scanLogs.Count > MAX_LOG_COUNT)
             {
-                totalSuccessElapsed = totalSuccessElapsed.Add(item.Elapsed);
+                this.scanLogs.Dequeue();
             }
-
-            return totalSuccessElapsed / totalScanCount;
         }
     }
 }

FastGithub.Scanner/Middlewares/StatisticsMiddleware.cs

@@ -28,16 +28,12 @@ namespace FastGithub.Scanner.Middlewares
             finally
             {
                 stopwatch.Stop();
+                context.History.Add(context.Available, stopwatch.Elapsed);
 
-                if (context.Available)
+                if (context.History.AvailableRate > 0d)
                 {
-                    context.History.AddSuccess(stopwatch.Elapsed);
                     this.logger.LogInformation(context.ToString());
                 }
-                else
-                {
-                    context.History.AddFailure(); 
-                }
             }
         }
     }

FastGithub/appsettings.json

@@ -1,6 +1,7 @@
 {
   "Dns": {
-    "UpStream": "114.114.114.114"
+    "UpStream": "114.114.114.114",
+    "GithubTTL": "00.10.00"
   },
   "Github": {
     "ScanAllInterval": "02:00:00", // 完整扫描时间间隔

README.md

@@ -4,7 +4,7 @@ github定制版的dns服务，解析访问github最快的ip
 ### 加速原理
 * 使用github公开的ip范围，扫描所有可用的ip；
 * 轮询检测并统计可用ip的访问成功率与访问耗时；
-* 拦截dns，访问github时，服务端模拟TTL，返回最优ip；
+* 拦截dns，访问github时返回最优ip；
 
 ### 使用说明
 在局域网服务器(没有就使用本机)运行本程序，将网络连接的dns设置为程序运行的机器的ip。