Session check standarization (#5388)

Thanks to @Lemongrass3110

src/common/socket.cpp

@@ -1733,7 +1733,7 @@ void send_shortlist_do_sends()
 
 			// If the session still exists, is not eof and has things left to
 			// be sent from it we'll re-add it to the shortlist.
-			if( session[fd] && !session[fd]->flag.eof && session[fd]->wdata_size )
+			if( session_isActive(fd) && session[fd]->wdata_size )
 				send_shortlist_add_fd(fd);
 		}
 	}