fix various race conditions

clientconn.go

@@ -301,6 +301,8 @@ outer:
 		}
 	}
 
+	cc.ctxCancel()
+
 	cc.doClose(false)
 }
 

server.go

@@ -336,6 +336,8 @@ outer:
 		}
 	}
 
+	s.ctxCancel()
+
 	if s.udpRTCPListener != nil {
 		s.udpRTCPListener.close()
 	}

serverconn.go

@@ -235,6 +235,8 @@ func (sc *ServerConn) run() {
 		}
 	}()
 
+	sc.ctxCancel()
+
 	if sc.tcpFrameEnabled {
 		sc.tcpFrameWriteBuffer.Close()
 		<-sc.tcpFrameBackgroundWriteDone

serversession.go

@@ -318,6 +318,8 @@ func (ss *ServerSession) run() {
 		}
 	}()
 
+	ss.ctxCancel()
+
 	switch ss.state {
 	case ServerSessionStatePlay:
 		if *ss.setupProtocol == StreamProtocolUDP {