From 909a58a15c660f65847df6342aeb2a96eb2e6e37 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=99=88=E5=9B=BD=E4=BC=9F?= <366193849@qq.com>
Date: Wed, 17 Nov 2021 16:24:55 +0800
Subject: [PATCH] =?UTF-8?q?ipv6=E5=AE=A2=E6=88=B7=E7=AB=AF?=
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

---
 FastGithub.DomainResolve/DnsClient.cs         | 57 ++++++++++++++-----
 .../Dns/DnsInterceptor.cs                     | 14 ++---
 2 files changed, 48 insertions(+), 23 deletions(-)

diff --git a/FastGithub.DomainResolve/DnsClient.cs b/FastGithub.DomainResolve/DnsClient.cs
index 1453fcf..4c736a6 100644
--- a/FastGithub.DomainResolve/DnsClient.cs
+++ b/FastGithub.DomainResolve/DnsClient.cs
@@ -91,7 +91,10 @@ namespace FastGithub.DomainResolve
 
             foreach (var fallbackDns in this.fastGithubConfig.FallbackDns)
             {
-                yield return fallbackDns;
+                if (Socket.OSSupportsIPv6 || fallbackDns.AddressFamily != AddressFamily.InterNetworkV6)
+                {
+                    yield return fallbackDns;
+                }
             }
         }
 
@@ -153,17 +156,8 @@ namespace FastGithub.DomainResolve
                 ? (IRequestResolver)new TcpRequestResolver(dns)
                 : new UdpRequestResolver(dns, new TcpRequestResolver(dns), this.resolveTimeout);
 
-            var request = new Request
-            {
-                RecursionDesired = true,
-                OperationCode = OperationCode.Query
-            };
-
-            request.Questions.Add(new Question(new Domain(endPoint.Host), RecordType.A));
-            var clientRequest = new ClientRequest(resolver, request);
-            var response = await clientRequest.Resolve(cancellationToken);
-
-            var addresses = response.AnswerRecords
+            var answerRecords = await GetAnswerRecordsAsync(resolver, endPoint.Host, cancellationToken);
+            var addresses = answerRecords
                 .OfType<IPAddressResourceRecord>()
                 .Where(item => IPAddress.IsLoopback(item.IPAddress) == false)
                 .Select(item => item.IPAddress)
@@ -179,7 +173,7 @@ namespace FastGithub.DomainResolve
                 addresses = await OrderByConnectAnyAsync(addresses, endPoint.Port, cancellationToken);
             }
 
-            var timeToLive = response.AnswerRecords.First().TimeToLive;
+            var timeToLive = answerRecords.First().TimeToLive;
             if (timeToLive <= TimeSpan.Zero)
             {
                 timeToLive = this.defaultEmptyTtl;
@@ -187,6 +181,43 @@ namespace FastGithub.DomainResolve
 
             return new LookupResult(addresses, timeToLive);
         }
+
+        /// <summary>
+        /// 获取答案
+        /// </summary>
+        /// <param name="resolver"></param>
+        /// <param name="domain"></param> 
+        /// <param name="cancellationToken"></param>
+        /// <returns></returns>
+        private static async Task<IList<IResourceRecord>> GetAnswerRecordsAsync(IRequestResolver resolver, string domain, CancellationToken cancellationToken)
+        {
+            var answerRecords = await GetAnswerAsync(RecordType.A);
+            if (Socket.OSSupportsIPv6 == true)
+            {
+                var ipv6Records = await GetAnswerAsync(RecordType.AAAA);
+                foreach (var record in ipv6Records)
+                {
+                    answerRecords.Add(record);
+                }
+            }
+            return answerRecords;
+
+            async Task<IList<IResourceRecord>> GetAnswerAsync(RecordType recordType)
+            {
+                var request = new Request
+                {
+                    RecursionDesired = true,
+                    OperationCode = OperationCode.Query
+                };
+
+                request.Questions.Add(new Question(new Domain(domain), recordType));
+                var clientRequest = new ClientRequest(resolver, request);
+                var response = await clientRequest.Resolve(cancellationToken);
+                return response.AnswerRecords;
+            }
+        }
+
+
         /// <summary>
         /// 连接速度排序
         /// </summary>
diff --git a/FastGithub.PacketIntercept/Dns/DnsInterceptor.cs b/FastGithub.PacketIntercept/Dns/DnsInterceptor.cs
index a16d4d9..b3ea53a 100644
--- a/FastGithub.PacketIntercept/Dns/DnsInterceptor.cs
+++ b/FastGithub.PacketIntercept/Dns/DnsInterceptor.cs
@@ -142,16 +142,9 @@ namespace FastGithub.PacketIntercept.Dns
 
             // dns响应数据
             var response = Response.FromRequest(request);
-            if (question.Type == RecordType.A)
-            {
-                var record = new IPAddressResourceRecord(domain, IPAddress.Loopback, this.ttl);
-                response.AnswerRecords.Add(record);
-                this.logger.LogInformation($"{domain}->{IPAddress.Loopback}");
-            }
-            else
-            {
-                this.logger.LogInformation($"{domain}->NULL");
-            }
+            var loopback = question.Type == RecordType.A ? IPAddress.Loopback : IPAddress.Loopback.MapToIPv6();
+            var record = new IPAddressResourceRecord(domain, loopback, this.ttl);
+            response.AnswerRecords.Add(record);
             var responsePayload = response.ToArray();
 
             // 修改payload和包长 
@@ -187,6 +180,7 @@ namespace FastGithub.PacketIntercept.Dns
                 : WinDivertDirection.Inbound;
 
             WinDivert.WinDivertHelperCalcChecksums(winDivertBuffer, packetLength, ref winDivertAddress, WinDivertChecksumHelperParam.All);
+            this.logger.LogInformation($"{domain}->{loopback}");
         }