switch to BROKEN const delcration when error in data loop

srt/protocol.go

@@ -301,7 +301,7 @@ func (agent *SRTManager) process_data(packet *Packet) (*Packet) {
 	case SHUTDOWN:
 		// state 3 should raise error and shutdown tunnel,
 		// for now start cleanup procedure in 10s
-		agent.state = 3
+		agent.state = BROKEN
 		go CleanFiles(agent.stream_key, 10)
 	default:
 		return nil
@@ -325,7 +325,7 @@ func (agent *SRTManager) handle_data_storage(packet *Packet) {
 	}
 	// write out all possible packets
 	if err := agent.storage.Expunge(agent.output); err != nil {
-		agent.state = 4
+		agent.state = BROKEN
 	}
 }