From f78b2f78883e80344dd5173d95634f08381e8cf6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E9=99=88=E5=9B=BD=E4=BC=9F?= <366193849@qq.com>
Date: Sat, 18 Sep 2021 08:33:05 +0800
Subject: [PATCH] sizeof

---
 FastGithub.Dns/DnsInterceptor.cs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/FastGithub.Dns/DnsInterceptor.cs b/FastGithub.Dns/DnsInterceptor.cs
index 4213113..e9ae3fb 100644
--- a/FastGithub.Dns/DnsInterceptor.cs
+++ b/FastGithub.Dns/DnsInterceptor.cs
@@ -123,7 +123,7 @@ namespace FastGithub.Dns
 
             // 修改payload和包长 
             responsePayload.CopyTo(new Span<byte>(packet.PacketPayload, responsePayload.Length));
-            packetLength += (uint)responsePayload.Length - packet.PacketPayloadLength;
+            packetLength = (uint)((int)packetLength + responsePayload.Length - requestPayload.Length);
 
             // 修改ip包
             if (packet.IPv4Header != null)
@@ -145,7 +145,7 @@ namespace FastGithub.Dns
             var destPort = packet.UdpHeader->DstPort;
             packet.UdpHeader->DstPort = packet.UdpHeader->SrcPort;
             packet.UdpHeader->SrcPort = destPort;
-            packet.UdpHeader->Length = BinaryPrimitives.ReverseEndianness((ushort)(responsePayload.Length + 8));
+            packet.UdpHeader->Length = BinaryPrimitives.ReverseEndianness((ushort)(sizeof(UdpHeader) + responsePayload.Length));
 
             // 反转方向
             if (winDivertAddress.Direction == WinDivertDirection.Inbound)