恢复FallbackDns配置

FastGithub.Configuration/FastGithubConfig.cs

@@ -1,10 +1,9 @@
-using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.Options;
-using System;
+using Microsoft.Extensions.Options;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
+using System.Net;
 
 namespace FastGithub.Configuration
 {
@@ -13,22 +12,24 @@ namespace FastGithub.Configuration
     /// </summary>
     public class FastGithubConfig
     {
-        private readonly ILogger<FastGithubConfig> logger;
         private SortedDictionary<DomainPattern, DomainConfig> domainConfigs;
         private ConcurrentDictionary<string, DomainConfig?> domainConfigCache;
 
+        /// <summary>
+        /// 回退的dns
+        /// </summary>
+        public IPEndPoint[] FallbackDns { get; set; }
+
         /// <summary>
         /// FastGithub配置
         /// </summary>
         /// <param name="options"></param>
         /// <param name="logger"></param>
-        public FastGithubConfig(
-            IOptionsMonitor<FastGithubOptions> options,
-            ILogger<FastGithubConfig> logger)
+        public FastGithubConfig(IOptionsMonitor<FastGithubOptions> options)
         {
-            this.logger = logger;
             var opt = options.CurrentValue;
 
+            this.FallbackDns = ConvertToIPEndPoints(opt.FallbackDns).ToArray();
             this.domainConfigs = ConvertDomainConfigs(opt.DomainConfigs);
             this.domainConfigCache = new ConcurrentDictionary<string, DomainConfig?>();
 
@@ -41,14 +42,24 @@ namespace FastGithub.Configuration
         /// <param name="options"></param>
         private void Update(FastGithubOptions options)
         {
-            try
-            {
+            this.FallbackDns = ConvertToIPEndPoints(options.FallbackDns).ToArray();
             this.domainConfigs = ConvertDomainConfigs(options.DomainConfigs);
             this.domainConfigCache = new ConcurrentDictionary<string, DomainConfig?>();
         }
-            catch (Exception ex)
+
+        /// <summary>
+        /// 转换为IPEndPoint
+        /// </summary>
+        /// <param name="ipEndPoints"></param>
+        /// <returns></returns>
+        private static IEnumerable<IPEndPoint> ConvertToIPEndPoints(IEnumerable<string> ipEndPoints)
         {
-                this.logger.LogError(ex.Message);
+            foreach (var item in ipEndPoints)
+            {
+                if (IPEndPoint.TryParse(item, out var endPoint))
+                {
+                    yield return endPoint;
+                }
             }
         }
 

FastGithub.Configuration/FastGithubOptions.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 
 namespace FastGithub.Configuration
 {
@@ -12,6 +13,11 @@ namespace FastGithub.Configuration
         /// </summary>
         public int HttpProxyPort { get; set; }
 
+        /// <summary>
+        /// 回退的dns
+        /// </summary>
+        public string[] FallbackDns { get; set; } = Array.Empty<string>();
+
         /// <summary>
         /// 代理的域名配置
         /// </summary>

FastGithub.DomainResolve/DomainResolver.cs

@@ -22,6 +22,7 @@ namespace FastGithub.DomainResolve
         private readonly IMemoryCache disableIPAddressCache = new MemoryCache(Options.Create(new MemoryCacheOptions()));
 
         private readonly DnscryptProxy dnscryptProxy;
+        private readonly FastGithubConfig fastGithubConfig;
         private readonly ILogger<DomainResolver> logger;
 
         private readonly TimeSpan connectTimeout = TimeSpan.FromSeconds(5d);
@@ -31,19 +32,22 @@ namespace FastGithub.DomainResolve
         private readonly TimeSpan fallbackExpiration = TimeSpan.FromMinutes(2d);
         private readonly TimeSpan loopbackExpiration = TimeSpan.FromSeconds(5d);
 
-        private readonly IPEndPoint fallbackDns = new(IPAddress.Parse("114.114.114.114"), 53);
         private readonly ConcurrentDictionary<DnsEndPoint, SemaphoreSlim> semaphoreSlims = new();
 
         /// <summary>
         /// 域名解析器
         /// </summary>
         /// <param name="dnscryptProxy"></param>
+        /// <param name="fastGithubConfig"></param>
         /// <param name="logger"></param>
         public DomainResolver(
+
             DnscryptProxy dnscryptProxy,
+            FastGithubConfig fastGithubConfig,
             ILogger<DomainResolver> logger)
         {
             this.dnscryptProxy = dnscryptProxy;
+            this.fastGithubConfig = fastGithubConfig;
             this.logger = logger;
         }
 
@@ -105,11 +109,6 @@ namespace FastGithub.DomainResolve
             var expiration = this.dnscryptExpiration;
             address = await this.LookupByDnscryptAsync(domain, cancellationToken);
 
-            if (address == null)
-            {
-                address = await this.LookupByDnscryptAsync(domain, cancellationToken);
-            }
-
             if (address == null)
             {
                 expiration = this.fallbackExpiration;
@@ -147,7 +146,8 @@ namespace FastGithub.DomainResolve
             }
 
             var dnsClient = new DnsClient(dns, forceTcp: false);
-            return await this.LookupAsync(dnsClient, domain, cancellationToken);
+            var address = await this.LookupAsync(dnsClient, domain, cancellationToken);
+            return address ?? await this.LookupAsync(dnsClient, domain, cancellationToken);
         }
 
         /// <summary>
@@ -159,8 +159,16 @@ namespace FastGithub.DomainResolve
         /// <returns></returns>        
         private async Task<IPAddress?> LookupByFallbackAsync(DnsEndPoint domain, CancellationToken cancellationToken)
         {
-            var dnsClient = new DnsClient(this.fallbackDns, forceTcp: true);
-            return await this.LookupAsync(dnsClient, domain, cancellationToken);
+            foreach (var dns in this.fastGithubConfig.FallbackDns)
+            {
+                var dnsClient = new DnsClient(dns, forceTcp: true);
+                var address = await this.LookupAsync(dnsClient, domain, cancellationToken);
+                if (address != null)
+                {
+                    return address;
+                }
+            }
+            return default;
         }
 
         /// <summary>

FastGithub/appsettings.json

@@ -1,7 +1,11 @@
 {
   // 新增的子配置文件appsettings.*.json，重启应用程序才生效
   "FastGithub": {
-    "HttpProxyPort": 38457, // http代理端口，非windows才使用
+    "HttpProxyPort": 38457, // http代理端口，linux/osx平台使用
+    "FallbackDns": [ // dnscrypt-proxy不可用时使用
+      "114.114.114.114:53",
+      "8.8.8.8:53"
+    ],
     "DomainConfigs": {
       "*.fastgithub.com": { // 域名的*表示除.之外0到多个任意字符
         "TlsSni": false, // 指示tls握手时是否发送SNI