From 483d2573367c185934e52c14ad5d62da66681e28 Mon Sep 17 00:00:00 2001
From: Glonee <glonee@foxmail.com>
Date: Sun, 7 Sep 2025 11:25:00 +0800
Subject: [PATCH] http3: fix race in concurrent Transport.RoundTrip calls
 (#5323)

* http3: fix data race in Transport

* reset init Once
---
 http3/transport.go | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/http3/transport.go b/http3/transport.go
index 4085faca..103e9fb5 100644
--- a/http3/transport.go
+++ b/http3/transport.go
@@ -153,6 +153,13 @@ func (t *Transport) init() error {
 	if t.QUICConfig.MaxIncomingStreams == 0 {
 		t.QUICConfig.MaxIncomingStreams = -1 // don't allow any bidirectional streams
 	}
+	if t.Dial == nil {
+		udpConn, err := net.ListenUDP("udp", nil)
+		if err != nil {
+			return err
+		}
+		t.transport = &quic.Transport{Conn: udpConn}
+	}
 	return nil
 }
 
@@ -350,13 +357,6 @@ func (t *Transport) dial(ctx context.Context, hostname string) (*quic.Conn, clie
 
 	dial := t.Dial
 	if dial == nil {
-		if t.transport == nil {
-			udpConn, err := net.ListenUDP("udp", nil)
-			if err != nil {
-				return nil, nil, err
-			}
-			t.transport = &quic.Transport{Conn: udpConn}
-		}
 		dial = func(ctx context.Context, addr string, tlsCfg *tls.Config, cfg *quic.Config) (*quic.Conn, error) {
 			network := "udp"
 			udpAddr, err := t.resolveUDPAddr(ctx, network, addr)
@@ -448,6 +448,7 @@ func (t *Transport) Close() error {
 			return err
 		}
 		t.transport = nil
+		t.initOnce = sync.Once{}
 	}
 	return nil
 }