fix: tuic better stream close

transport/tuic/client.go

@@ -26,7 +26,7 @@ var (
 	TooManyOpenStreams = errors.New("tuic: too many open streams")
 )
 
-const MaxOpenStreams = 100 - 10
+const MaxOpenStreams = 100 - 90
 
 type Client struct {
 	TlsConfig             *tls.Config
@@ -230,9 +230,9 @@ func (t *Client) Close(err error) {
 			if conn, ok := value.(net.Conn); ok {
 				_ = conn.Close()
 			}
+			t.udpInputMap.Delete(key)
 			return true
 		})
-		t.udpInputMap = sync.Map{} // new one
 		t.quicConn = nil
 	}
 }
@@ -260,7 +260,12 @@ func (t *Client) DialContext(ctx context.Context, metadata *C.Metadata, dialFn f
 		if err != nil {
 			return nil, err
 		}
-		stream = &quicStreamConn{quicStream, quicConn.LocalAddr(), quicConn.RemoteAddr(), t}
+		stream = &quicStreamConn{
+			Stream: quicStream,
+			lAddr:  quicConn.LocalAddr(),
+			rAddr:  quicConn.RemoteAddr(),
+			client: t,
+		}
 		_, err = buf.WriteTo(stream)
 		if err != nil {
 			_ = stream.Close()
@@ -291,15 +296,34 @@ func (t *Client) DialContext(ctx context.Context, metadata *C.Metadata, dialFn f
 
 type quicStreamConn struct {
 	quic.Stream
+	lock   sync.Mutex
 	lAddr  net.Addr
 	rAddr  net.Addr
 	client *Client
 }
 
+func (q *quicStreamConn) Write(p []byte) (n int, err error) {
+	q.lock.Lock()
+	defer q.lock.Unlock()
+	return q.Stream.Write(p)
+}
+
 func (q *quicStreamConn) Close() error {
-	//defer q.client.openStreams.Add(-1)
+	defer time.AfterFunc(C.DefaultTCPTimeout, func() {
+		q.client.openStreams.Add(-1)
+	})
+
+	// https://github.com/cloudflare/cloudflared/commit/ed2bac026db46b239699ac5ce4fcf122d7cab2cd
+	// Make sure a possible writer does not block the lock forever. We need it, so we can close the writer
+	// side of the stream safely.
+	_ = q.Stream.SetWriteDeadline(time.Now())
+
+	// This lock is eventually acquired despite Write also acquiring it, because we set a deadline to writes.
+	q.lock.Lock()
+	defer q.lock.Unlock()
+
+	// We have to clean up the receiving stream ourselves since the Close in the bottom does not handle that.
 	q.Stream.CancelRead(0)
-	q.Stream.CancelWrite(0)
 	return q.Stream.Close()
 }