From 34653a754f067c4cac103398d90d135bd5e1111f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=80=81=E4=B9=9D?= <366193849@qq.com>
Date: Thu, 18 Nov 2021 22:58:37 +0800
Subject: [PATCH] =?UTF-8?q?=E8=87=AA=E5=8A=A8=E4=BF=9D=E5=AD=98dns?=
 =?UTF-8?q?=E8=AE=B0=E5=BD=95?=
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---
 FastGithub.DomainResolve/DomainResolver.cs | 102 ++++++++++++++++++++-
 1 file changed, 100 insertions(+), 2 deletions(-)

diff --git a/FastGithub.DomainResolve/DomainResolver.cs b/FastGithub.DomainResolve/DomainResolver.cs
index ea8313a..d4ac96f 100644
--- a/FastGithub.DomainResolve/DomainResolver.cs
+++ b/FastGithub.DomainResolve/DomainResolver.cs
@@ -3,9 +3,11 @@ using Microsoft.Extensions.Logging;
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Net;
 using System.Runtime.CompilerServices;
+using System.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -16,7 +18,18 @@ namespace FastGithub.DomainResolve
     /// </summary> 
     sealed class DomainResolver : IDomainResolver
     {
+        private record EndPointItem(string Host, int Port);
+        private static readonly string dnsEndpointFile = "dnsendpoints.json";
+        private static readonly SemaphoreSlim dnsEndpointLocker = new(1, 1);
+        private static readonly JsonSerializerOptions jsonOptions = new JsonSerializerOptions
+        {
+            WriteIndented = true,
+            PropertyNameCaseInsensitive = true,
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+        };
+
         private readonly DnsClient dnsClient;
+        private readonly FastGithubConfig fastGithubConfig;
         private readonly ILogger<DomainResolver> logger;
         private readonly ConcurrentDictionary<DnsEndPoint, IPAddressElapsedCollection> dnsEndPointAddressElapseds = new();
 
@@ -24,13 +37,94 @@ namespace FastGithub.DomainResolve
         /// 域名解析器
         /// </summary>
         /// <param name="dnsClient"></param>
+        /// <param name="fastGithubConfig"></param>
         /// <param name="logger"></param>
-        public DomainResolver(DnsClient dnsClient, ILogger<DomainResolver> logger)
+        public DomainResolver(
+            DnsClient dnsClient,
+            FastGithubConfig fastGithubConfig,
+            ILogger<DomainResolver> logger)
         {
             this.dnsClient = dnsClient;
+            this.fastGithubConfig = fastGithubConfig;
             this.logger = logger;
+
+            foreach (var endPoint in this.ReadDnsEndPoints())
+            {
+                this.dnsEndPointAddressElapseds.TryAdd(endPoint, IPAddressElapsedCollection.Empty);
+            }
         }
 
+
+        /// <summary>
+        /// 读取保存的节点
+        /// </summary>
+        /// <returns></returns>
+        private IList<DnsEndPoint> ReadDnsEndPoints()
+        {
+            if (File.Exists(dnsEndpointFile) == false)
+            {
+                return Array.Empty<DnsEndPoint>();
+            }
+
+            try
+            {
+                dnsEndpointLocker.Wait();
+
+                var utf8Json = File.ReadAllBytes(dnsEndpointFile);
+                var endPointItems = JsonSerializer.Deserialize<EndPointItem[]>(utf8Json, jsonOptions);
+                if (endPointItems == null)
+                {
+                    return Array.Empty<DnsEndPoint>();
+                }
+
+                var dnsEndPoints = new List<DnsEndPoint>();
+                foreach (var item in endPointItems)
+                {
+                    if (this.fastGithubConfig.IsMatch(item.Host))
+                    {
+                        dnsEndPoints.Add(new DnsEndPoint(item.Host, item.Port));
+                    }
+                }
+                return dnsEndPoints;
+            }
+            catch (Exception ex)
+            {
+                this.logger.LogWarning(ex.Message, "读取dns记录异常");
+                return Array.Empty<DnsEndPoint>();
+            }
+            finally
+            {
+                dnsEndpointLocker.Release();
+            }
+        }
+
+        /// <summary>
+        /// 保存节点到文件
+        /// </summary>
+        /// <param name="dnsEndPoints"></param>
+        /// <param name="cancellationToken"></param>
+        /// <returns></returns>
+        private async Task WriteDnsEndPointsAsync(IEnumerable<DnsEndPoint> dnsEndPoints, CancellationToken cancellationToken)
+        {
+            try
+            {
+                await dnsEndpointLocker.WaitAsync(CancellationToken.None);
+
+                var endPointItems = dnsEndPoints.Select(item => new EndPointItem(item.Host, item.Port)).ToArray();
+                var utf8Json = JsonSerializer.SerializeToUtf8Bytes(endPointItems, jsonOptions);
+                await File.WriteAllBytesAsync(dnsEndpointFile, utf8Json, cancellationToken);
+            }
+            catch (Exception ex)
+            {
+                this.logger.LogWarning(ex.Message, "保存dns记录异常");
+            }
+            finally
+            {
+                dnsEndpointLocker.Release();
+            }
+        }
+
+
         /// <summary>
         /// 解析ip
         /// </summary>
@@ -64,7 +158,11 @@ namespace FastGithub.DomainResolve
             }
             else
             {
-                this.dnsEndPointAddressElapseds.TryAdd(endPoint, IPAddressElapsedCollection.Empty);
+                if (this.dnsEndPointAddressElapseds.TryAdd(endPoint, IPAddressElapsedCollection.Empty))
+                {
+                    await this.WriteDnsEndPointsAsync(this.dnsEndPointAddressElapseds.Keys, cancellationToken);
+                }
+
                 await foreach (var adddress in this.dnsClient.ResolveAsync(endPoint, fastSort: true, cancellationToken))
                 {
                     this.logger.LogInformation($"{endPoint.Host}->{adddress}");