Fix quic-go write leak

transport/v2rayquic/client.go

@@ -78,6 +78,12 @@ func (c *Client) offerNew() (*quic.Conn, error) {
 		packetConn.Close()
 		return nil, err
 	}
+	// quic-go does not take ownership of the packet conn passed to Dial:
+	// when the connection ends it only stops reading.
+	go func() {
+		<-quicConn.Context().Done()
+		packetConn.Close()
+	}()
 	c.conn.Store(quicConn)
 	c.rawConn = udpConn
 	return quicConn, nil

transport/v2rayquic/stream.go

@@ -2,6 +2,7 @@ package v2rayquic
 
 import (
 	"net"
+	"time"
 
 	"github.com/sagernet/quic-go"
 	qtls "github.com/sagernet/sing-quic"
@@ -37,5 +38,8 @@ func (s *StreamWrapper) Upstream() any {
 func (s *StreamWrapper) Close() error {
 	s.CancelRead(0)
 	s.Stream.Close()
+	// quic-go's Stream.Close does not unblock a Write blocked on flow control,
+	// but a past write deadline does; buffered data and the FIN are unaffected.
+	s.Stream.SetWriteDeadline(time.Now())
 	return nil
 }