自动侦测本机ip做为dns响应值

FastGithub.Dns/DnsHostedService.cs

@@ -40,7 +40,9 @@ namespace FastGithub.Dns
         {
             this.options = options;
             this.logger = logger;
-            this.requestResolver = new CompositeRequestResolver(IPAddress.Parse(options.Value.UpStream), githubRequestResolver);
+
+            var upStream = IPAddress.Parse(options.Value.UpStream);
+            this.requestResolver = new CompositeRequestResolver(upStream, githubRequestResolver);
         }
 
         /// <summary>
@@ -57,7 +59,8 @@ namespace FastGithub.Dns
             }
 
             this.logger.LogInformation("dns服务启动成功");
-            this.dnsAddresses = this.SetNameServers(IPAddress.Loopback, IPAddress.Parse(this.options.Value.UpStream));
+            var upStream = IPAddress.Parse(options.Value.UpStream);
+            this.dnsAddresses = this.SetNameServers(IPAddress.Loopback, upStream);
             return base.StartAsync(cancellationToken);
         }
 
@@ -74,7 +77,7 @@ namespace FastGithub.Dns
                 var result = await this.socket.ReceiveFromAsync(this.buffer, SocketFlags.None, remoteEndPoint);
                 var datas = new byte[result.ReceivedBytes];
                 this.buffer.AsSpan(0, datas.Length).CopyTo(datas);
-                this.HandleRequestAsync(datas, result.RemoteEndPoint, stoppingToken);
+                this.HandleRequestAsync(datas, (IPEndPoint)result.RemoteEndPoint, stoppingToken);
             }
         }
 
@@ -84,12 +87,13 @@ namespace FastGithub.Dns
         /// <param name="datas"></param>
         /// <param name="remoteEndPoint"></param>
         /// <param name="cancellationToken"></param>
-        private async void HandleRequestAsync(byte[] datas, EndPoint remoteEndPoint, CancellationToken cancellationToken)
+        private async void HandleRequestAsync(byte[] datas, IPEndPoint remoteEndPoint, CancellationToken cancellationToken)
         {
             try
             {
                 var request = Request.FromArray(datas);
-                var response = await this.requestResolver.Resolve(request, cancellationToken);
+                var remoteRequest = new RemoteRequest(request, remoteEndPoint.Address);
+                var response = await this.requestResolver.Resolve(remoteRequest, cancellationToken);
                 await this.socket.SendToAsync(response.ToArray(), SocketFlags.None, remoteEndPoint);
             }
             catch (Exception ex)

FastGithub.Dns/DnsOptions.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Net;
 
 namespace FastGithub.Dns
 {
@@ -28,10 +27,5 @@ namespace FastGithub.Dns
         /// 是否使用反向代理访问github
         /// </summary>
         public bool UseGithubReverseProxy { get; set; } = true; 
-
-        /// <summary>
-        /// dns响应的反向代理服务的ip
-        /// </summary>
-        public string GithubReverseProxyIPAddress { get; set; } = IPAddress.Loopback.ToString();
     }
 }

FastGithub.Dns/GithubRequestResolver.cs

@@ -48,38 +48,55 @@ namespace FastGithub.Dns
         public Task<IResponse> Resolve(IRequest request, CancellationToken cancellationToken = default)
         {
             IResponse response = Response.FromRequest(request);
-            var question = request.Questions.FirstOrDefault();
+            if (request is not RemoteRequest remoteRequest)
+            {
+                return Task.FromResult(response);
+            }
 
+            var question = request.Questions.FirstOrDefault();
             if (question == null || question.Type != RecordType.A)
             {
                 return Task.FromResult(response);
             }
 
-            var domain = question.Name.ToString();
+            var domain = question.Name;
-            if (this.githubResolver.IsSupported(domain) == false)
+            if (this.githubResolver.IsSupported(domain.ToString()) == false)
             {
                 return Task.FromResult(response);
             }
 
-            if (this.options.CurrentValue.UseGithubReverseProxy == false)
+            var record = this.GetAnswerRecord(remoteRequest, domain);
+            if (record != null)
             {
-                var address = this.githubResolver.Resolve(domain);
+                this.logger.LogInformation($"[{domain}->{record.IPAddress}]");
-                if (address != null)
-                {
-                    var ttl = this.options.CurrentValue.GithubTTL;
-                    var record = new IPAddressResourceRecord(question.Name, address, ttl);
-                    response.AnswerRecords.Add(record);
-                    this.logger.LogInformation($"[{domain}->{address}]");
-                }
-            }
-            else
-            {
-                var address = IPAddress.Parse(this.options.CurrentValue.GithubReverseProxyIPAddress);
-                var record = new IPAddressResourceRecord(question.Name, address, TimeSpan.FromMinutes(1));
                 response.AnswerRecords.Add(record);
-                this.logger.LogInformation($"[{domain}->{address}]");
             }
+
             return Task.FromResult(response);
         }
+
+        /// <summary>
+        /// 获取答案
+        /// </summary>
+        /// <param name="request"></param>
+        /// <param name="domain"></param>
+        /// <returns></returns>
+        private IPAddressResourceRecord? GetAnswerRecord(RemoteRequest request, Domain domain)
+        {
+            if (this.options.CurrentValue.UseGithubReverseProxy == true)
+            {
+                var localAddress = request.GetLocalAddress() ?? IPAddress.Loopback;
+                return new IPAddressResourceRecord(domain, localAddress, TimeSpan.FromMinutes(1d));
+            }
+
+            var githubAddress = this.githubResolver.Resolve(domain.ToString());
+            if (githubAddress == null)
+            {
+                return default;
+            }
+
+            var ttl = this.options.CurrentValue.GithubTTL;
+            return new IPAddressResourceRecord(domain, githubAddress, ttl);
+        }
     }
 }

FastGithub.Dns/RemoteRequest.cs

@@ -0,0 +1,77 @@
+using DNS.Protocol;
+using System.Buffers.Binary;
+using System.Net;
+using System.Net.NetworkInformation;
+
+namespace FastGithub.Dns
+{
+    /// <summary>
+    /// 远程请求
+    /// </summary>
+    sealed class RemoteRequest : Request
+    {
+        /// <summary>
+        /// 获取远程地址
+        /// </summary>
+        public IPAddress RemoteAddress { get; }
+
+        /// <summary>
+        /// 远程请求
+        /// </summary>
+        /// <param name="request"></param>
+        /// <param name="remoteAddress"></param>
+        public RemoteRequest(Request request, IPAddress remoteAddress)
+            : base(request)
+        {
+            this.RemoteAddress = remoteAddress;
+        }
+
+        /// <summary>
+        /// 获取对应的本机地址
+        /// </summary> 
+        /// <returns></returns>
+        public IPAddress? GetLocalAddress()
+        {
+            foreach (var @interface in NetworkInterface.GetAllNetworkInterfaces())
+            {
+                var addresses = @interface.GetIPProperties().UnicastAddresses;
+                foreach (var item in addresses)
+                {
+                    if (IsInSubNet(item.IPv4Mask, item.Address, this.RemoteAddress))
+                    {
+                        return item.Address;
+                    }
+                }
+            }
+            return default;
+        }
+
+        /// <summary>
+        /// 是否在相同的子网里
+        /// </summary>
+        /// <param name="mask"></param>
+        /// <param name="local"></param>
+        /// <param name="remote"></param>
+        /// <returns></returns>
+        private static bool IsInSubNet(IPAddress mask, IPAddress local, IPAddress remote)
+        {
+            if (local.AddressFamily != remote.AddressFamily)
+            {
+                return false;
+            }
+
+            var maskValue = GetValue(mask);
+            var localValue = GetValue(local);
+            var remoteValue = GetValue(remote);
+            return (maskValue & localValue) == (maskValue & remoteValue);
+
+            static long GetValue(IPAddress address)
+            {
+                var bytes = address.GetAddressBytes();
+                return bytes.Length == sizeof(int)
+                    ? BinaryPrimitives.ReadInt32BigEndian(bytes)
+                    : BinaryPrimitives.ReadInt64BigEndian(bytes);
+            }
+        }
+    }
+}

FastGithub/appsettings.json

@@ -3,8 +3,7 @@
     "UpStream": "114.114.114.114", // 上游dns
     "GithubTTL": "00:10:00", // github相关域名解析结果的存活时长
     "SetToLocalMachine": true, // 是否设置本机使用此dns(仅支持windows)   
-    "UseGithubReverseProxy": true, // 是否使用反向代理访问github以解决连接被重复的问题
+    "UseGithubReverseProxy": true // 是否使用反向代理访问github以解决连接被重复的问题 
-    "GithubReverseProxyIPAddress": "127.0.0.1" // dns响应的反向代理服务ip，局域网部署时要填写局域网ip
   },
   "Lookup": { // ip查找     
     "IPAddressComProvider": {