From d8994b7603d4a66910ac5d3cdb7d8af6c560f9bd Mon Sep 17 00:00:00 2001
From: ll11l1lIllIl1lll <88377095+ll11l1lIllIl1lll@users.noreply.github.com>
Date: Fri, 19 Jul 2024 17:52:34 +0000
Subject: [PATCH] Fix SplitHTTP H3 crash on v2rayNG (#3559)

Fixes https://github.com/XTLS/Xray-core/issues/3556
---
 transport/internet/splithttp/dialer.go | 29 ++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/transport/internet/splithttp/dialer.go b/transport/internet/splithttp/dialer.go
index 9f98da3d..5c22f845 100644
--- a/transport/internet/splithttp/dialer.go
+++ b/transport/internet/splithttp/dialer.go
@@ -101,11 +101,32 @@ func getHTTPClient(ctx context.Context, dest net.Destination, streamSettings *in
 				if err != nil {
 					return nil, err
 				}
-				udpAddr, err := net.ResolveUDPAddr("udp", conn.RemoteAddr().String())
-				if err != nil {
-					return nil, err
+
+				var udpConn *net.UDPConn
+				var udpAddr *net.UDPAddr
+
+				switch c := conn.(type) {
+				case *internet.PacketConnWrapper:
+					var ok bool
+					udpConn, ok = c.Conn.(*net.UDPConn)
+					if !ok {
+						return nil, errors.New("PacketConnWrapper does not contain a UDP connection")
+					}
+					udpAddr, err = net.ResolveUDPAddr("udp", c.Dest.String())
+					if err != nil {
+						return nil, err
+					}
+				case *net.UDPConn:
+					udpConn = c
+					udpAddr, err = net.ResolveUDPAddr("udp", c.RemoteAddr().String())
+					if err != nil {
+						return nil, err
+					}
+				default:
+					return nil, errors.New("unsupported connection type: %T", conn)
 				}
-				return quic.DialEarly(ctx, conn.(*internet.PacketConnWrapper).Conn.(*net.UDPConn), udpAddr, tlsCfg, cfg)
+
+				return quic.DialEarly(ctx, udpConn, udpAddr, tlsCfg, cfg)
 			},
 		}
 		downloadTransport = roundTripper