Keep streams from being set up after closeAllStreamReaders is called

staging/src/k8s.io/client-go/tools/remotecommand/websocket.go

@@ -187,6 +187,9 @@ type wsStreamCreator struct {
 	// map of stream id to stream; multiple streams read/write the connection
 	streams   map[byte]*stream
 	streamsMu sync.Mutex
+	// setStreamErr holds the error to return to anyone calling setStreams.
+	// this is populated in closeAllStreamReaders
+	setStreamErr error
 }
 
 func newWSStreamCreator(conn *gwebsocket.Conn) *wsStreamCreator {
@@ -202,10 +205,14 @@ func (c *wsStreamCreator) getStream(id byte) *stream {
 	return c.streams[id]
 }
 
-func (c *wsStreamCreator) setStream(id byte, s *stream) {
+func (c *wsStreamCreator) setStream(id byte, s *stream) error {
 	c.streamsMu.Lock()
 	defer c.streamsMu.Unlock()
+	if c.setStreamErr != nil {
+		return c.setStreamErr
+	}
 	c.streams[id] = s
+	return nil
 }
 
 // CreateStream uses id from passed headers to create a stream over "c.conn" connection.
@@ -228,7 +235,11 @@ func (c *wsStreamCreator) CreateStream(headers http.Header) (httpstream.Stream,
 		connWriteLock: &c.connWriteLock,
 		id:            id,
 	}
-	c.setStream(id, s)
+	if err := c.setStream(id, s); err != nil {
+		_ = s.writePipe.Close()
+		_ = s.readPipe.Close()
+		return nil, err
+	}
 	return s, nil
 }
 
@@ -312,7 +323,7 @@ func (c *wsStreamCreator) readDemuxLoop(bufferSize int, period time.Duration, de
 }
 
 // closeAllStreamReaders closes readers in all streams.
-// This unblocks all stream.Read() calls.
+// This unblocks all stream.Read() calls, and keeps any future streams from being created.
 func (c *wsStreamCreator) closeAllStreamReaders(err error) {
 	c.streamsMu.Lock()
 	defer c.streamsMu.Unlock()
@@ -320,6 +331,12 @@ func (c *wsStreamCreator) closeAllStreamReaders(err error) {
 		// Closing writePipe unblocks all readPipe.Read() callers and prevents any future writes.
 		_ = s.writePipe.CloseWithError(err)
 	}
+	// ensure callers to setStreams receive an error after this point
+	if err != nil {
+		c.setStreamErr = err
+	} else {
+		c.setStreamErr = fmt.Errorf("closed all streams")
+	}
 }
 
 type stream struct {

staging/src/k8s.io/client-go/tools/remotecommand/websocket_test.go

@@ -1116,6 +1116,14 @@ func TestWebSocketClient_HeartbeatSucceeds(t *testing.T) {
 	wg.Wait()
 }
 
+func TestLateStreamCreation(t *testing.T) {
+	c := newWSStreamCreator(nil)
+	c.closeAllStreamReaders(nil)
+	if err := c.setStream(0, nil); err == nil {
+		t.Fatal("expected error adding stream after closeAllStreamReaders")
+	}
+}
+
 func TestWebSocketClient_StreamsAndExpectedErrors(t *testing.T) {
 	// Validate Stream functions.
 	c := newWSStreamCreator(nil)