Use new flag that indicates a socket as a filedescriptor getter.

@@ -99,8 +99,7 @@ TR_commManagerEpollSelect(void * _this, TR_Event event, unsigned long timeout)
 		int             handle   = endpoint->transport->handle;
 
 		if ((events[i].events & EPOLLIN) == EPOLLIN) {
-			if (TR_INSTANCE_OF(TR_TcpSocket, endpoint->transport)
-					&& ((TR_TcpSocket)endpoint->transport)->listen) {
+			if (TR_socketFdGetter(endpoint->transport)) {
 				TR_setAdd(cmgr->accept, endpoint);
 			} else {
 				if (! event->subject->fin) {

@@ -95,8 +95,7 @@ TR_commManagerPollSelect(void * _this, TR_Event event, unsigned long timeout)
 				nevents--;
 
 				if ((this->fds[i].revents & POLLIN) == POLLIN) {
-					if (TR_INSTANCE_OF(TR_TcpSocket, endpoint->transport)
-							&& ((TR_TcpSocket)endpoint->transport)->listen) {
+					if (TR_socketFdGetter(endpoint->transport)) {
 						TR_setAdd(cmgr->accept, endpoint);
 					} else {
 						if (! event->subject->fin) {

@@ -50,8 +50,7 @@ TR_commManagerAddEndpoint(void * _this, TR_CommEndPoint endpoint)
 
 	this->endpoints[endpoint->transport->handle] = endpoint;
 
-	if (TR_INSTANCE_OF(TR_TcpSocket, endpoint->transport)
-			&& ((TR_TcpSocket)endpoint->transport)->listen) {
+	if (TR_socketFdGetter(endpoint->transport)) {
 		TR_setAdd(this->accept, endpoint);
 		TR_ISSUE_IO_ACC_EVENT(this, endpoint);
 	} else {
@@ -117,8 +116,7 @@ TR_commManagerPollRead(void * _this, TR_Event event)
 	TR_CommManager this      = _this;
 	TR_CommEndPoint endpoint = (TR_CommEndPoint)event->subject;
 
-	if (TR_INSTANCE_OF(TR_TcpSocket, endpoint->transport)
-			&& ((TR_TcpSocket)endpoint->transport)->listen) {
+	if (TR_socketFdGetter(endpoint->transport)) {
 		TR_setDelete(this->accept, event->subject);
 	} else {
 		TR_setDelete(this->read, event->subject);