From a568a05bf749299fd328906f2ab4537199f1d47d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=80=81=E4=B9=9D?= <366193849@qq.com>
Date: Fri, 17 Sep 2021 22:11:38 +0800
Subject: [PATCH] =?UTF-8?q?=E5=85=BC=E5=AE=B9ipv6?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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---
 FastGithub.Dns/DnsInterceptor.cs | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/FastGithub.Dns/DnsInterceptor.cs b/FastGithub.Dns/DnsInterceptor.cs
index 750bc34..4213113 100644
--- a/FastGithub.Dns/DnsInterceptor.cs
+++ b/FastGithub.Dns/DnsInterceptor.cs
@@ -126,10 +126,20 @@ namespace FastGithub.Dns
             packetLength += (uint)responsePayload.Length - packet.PacketPayloadLength;
 
             // 修改ip包
-            var destAddress = packet.IPv4Header->DstAddr;
-            packet.IPv4Header->DstAddr = packet.IPv4Header->SrcAddr;
-            packet.IPv4Header->SrcAddr = destAddress;
-            packet.IPv4Header->Length = BinaryPrimitives.ReverseEndianness((ushort)packetLength);
+            if (packet.IPv4Header != null)
+            {
+                var destAddress = packet.IPv4Header->DstAddr;
+                packet.IPv4Header->DstAddr = packet.IPv4Header->SrcAddr;
+                packet.IPv4Header->SrcAddr = destAddress;
+                packet.IPv4Header->Length = BinaryPrimitives.ReverseEndianness((ushort)packetLength);
+            }
+            else
+            {
+                var destAddress = packet.IPv6Header->DstAddr;
+                packet.IPv6Header->DstAddr = packet.IPv6Header->SrcAddr;
+                packet.IPv6Header->SrcAddr = destAddress;
+                packet.IPv6Header->Length = BinaryPrimitives.ReverseEndianness((ushort)packetLength);
+            }
 
             // 修改udp包
             var destPort = packet.UdpHeader->DstPort;