Fix vless UDP 443 block

proxy/drop.go

@@ -0,0 +1,24 @@
+package proxy
+
+import (
+	"context"
+	"math/rand/v2"
+	"time"
+
+	"github.com/xtls/xray-core/common"
+	"github.com/xtls/xray-core/common/buf"
+	"github.com/xtls/xray-core/common/signal"
+)
+
+// wait to drain all the possible incoming UDP data
+// because re-established QUIC UDP may bypass the sniffer
+func DropUDP(ctx context.Context, reader buf.Reader) {
+	ctx, cancel := context.WithCancel(ctx)
+	timer := signal.CancelAfterInactivity(ctx, func() {
+		cancel()
+	}, time.Duration(30+rand.N(60))*time.Second)
+	context.AfterFunc(ctx, func() {
+		common.Interrupt(reader)
+	})
+	buf.Copy(reader, buf.Discard, buf.UpdateActivity(timer))
+}